NUTRITIONAL STUDIES ON RANCHeMESED MINK Thesis for ”18 Degree of DH. D. MECHEGAN STATE UNIVERSETY Hugh Farrant Travis 1960 I\\Tfi\\\'\m\i\fi\\ii\i\iMWWI 3 1293 1991) ngig. ”M This is to certify that the thesis entitled Nutritional Studies on Ranch-Raised Mink presented by Hugh Farrant Travis has been accepted towards fulfillment of the requirements for Ph.D. degree in Poultry Science Q44 MAW tic/r professor Date December 29, 1960 LIBRARY Michigan State University ABSTRACT NUTRITIONAL STUDIES ON RANCH-RAISED MINK by Hugh Farrant Travis Investigations on ranch-raised mink were conducted at M.S.U. over a fiveqyear period: (1) to evaluate diets containing no fresh animal products; (2) to determine requirements for various nutrients using semi- purified rations; and (3) to study any possible effects of certain anti- biotics and hormones during the reproductive cycle. Dry diets containing no fresh animal products, or supplemented with fresh liver or tripe, were fed through two growth and two reproduc- tion periods. Total weight gains of the mink on dry diets were less than those of the mink on the ranch ration. Mink on dry diets grew more slowly than the controls during the period from 11 weeks to 16 weeks of age. However, from 16 weeks to 29 weeks the growth of the mink on dry diets was more rapid. Growth response of mink receiving the dry diet supple- mented with 25 percent fresh liver was intermediate between mink receiving the ranch ration and those receiving the dry diet. Fur quality and length of the live mink were as good on the dry diets as on ranch rations. Increasing the fat level in the dry rations from 12 to 20 percent improved the growth rate of kits. No beneficial effect was apparent from further increasing the fat to 28 percent. Male mink showed a greater re- aponse to changes in diets than females. Adult mink fed dry diets prior to breeding and then dry diets with fresh liver during periods of breeding, gestation and lactatidn, were comparable in weight, breeding performance and number of kits whelped per female to mink fed a typical commercial ranch ration. However, Hugh Farrant Travis 21-day kit weights of the controls were greater. The response from adding fresh liver or from adding fresh tripe to dry diets during lactation and early kit growth was similar. This indicates that perhaps the value of the fresh animal products may be due to palatability rather than the nutrient values it contributed. Semi-purified diets were used to ascertain if adult mink require dietary vitamin K, whether dark mink differ in this respect from sapphire mink, and if the feeding of sulfaquinoxaline or certain antibiotics affect blood clotting time. The dietary requirement of vitamin K for normal adult mink was found to be less than 13 milligrams of menadione sodium bisulfite per ton of feed. Sulfaquinoxaline fed for six to eight days at 0.5 percent or higher, significantly increased whole blood prothrombin clotting time, while addition of aureomycin or terramycin at levels of #00 grams per ton of food did not. Experiments were conducted during two growing seasons to determine the protein and amino acid requirements for growing mink. Depletion- repletion and growth study techniques were applied with partial success. Growing mink maintained their weights for short periods of time on semi- purified diets containing 15 percent protein and 20 percent fat when sup- plemented.with appropriate amino acids. Terramycin was fed at 400 grams per ton of feed during two lactation and early kit growth seasons. There was no beneficial effect in kit pro- duction, growth or mortality that could be attributed to the antibiotic treatment. Kit weights at 21 days from mothers receiving the antibiotics were significantly smaller than those of the controls during one year's Stlldyo Hugh Farrant Travis Thyroprotein containing one percent thyroactive iodinated casein was fed to pregnant females at levels of 0.53 milligrams per 100 grams of body weight, starting five days before the first litter was to be ex- pected and continuing until the young were two weeks old. There was no effect on number of kits born or incidence of mortality of the young. Kits from treated.mothers were significantly smaller at 1# days of age. Diethylstilbestrol was fed intermittently to bred females, start- ing after implantation and continuing through late gestation, whelping and early kit growth. Results were almost complete failure of reproductive processes, and resulted in reabsorption, lowered kit production and kit weights, as well as greater kit mortality. NUTRITIONAL STUDIES ON RANCH-RAISED MINK by Hugh Farrant Travis A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY Department of Poultry Science 1960 Acknowledgments The author wishes to express his appreciation to Dr. Philip J. Schaible for his interest, guidance and encouragement throughout our association. He is also indebted to Dr. Howard C. Zindel for assistance during this study, and to Dr. Irwin J. Benne, Department of Agricultural Chemistry, for the analyses of the experimental rations. Appreciation is also expressed to Drs. Theo H. Coleman, Robert K. Ringer and E. Paul Reineke for aid and assistance during the course of these investigations. Sincere acknowledgment is also made to the Brewers Yeast Council, Sulfite Pulp Paper League, Mink Farmer's Research Foundation, Abbott Laboratories, Chas. Pfizer and Company, Distillation Products Industries and Armour and Company for their support and financial assistance in these studies. Finally, the author is indebted to his wife, Dorothea, whose patience and encouragement during this strenuous period of study and research made it worthwhile. ii TABLE IntrOduCtion o o o o o o o o o 0 General Review of Literature . . DigeStibility o o o o o 0 Rate of Food Passage. . . Nutritive Requirements. . General Materials and Methods. . Animals 0 o o o o o o o 0 Housing and Management. . Evaluation of Response. . StUdieS 0f Dry Diets o o o o o 0 Introduction. . . . . Review of Literature. Growth Studies - 1956 Growth Studies - 1957 Reproduction Studies - 1957 Reproduction Studies - 1958 DiSCHSSiono o o o o o o o 0 Summary and Conclusions . . Vitamin K StUdieSo o o o o o o o IntrOduCtiono o o o o o 0 Procedure 0 o o o o o o 0 Results and Discussion. . Summary and Conclusions . . Studies of Amino Acid Requirements Introduction. Procedure . . 1958 Studies. 1959 Studies. Discussion. . Summary and Conclusions OF CONTENTS of Growing Mink iii 0 O O O O O O O tfi‘d‘dt’rt Page \O(b(n (D (hChkn I? he ya ya \oxc éE\0t0{:€3l$l: \n kn Kn K» 66 67 67 67 88 D Page The Effects of Intermittent Doses of Diethylstilbestrol During Gestation on the Reproduction of Mink . . . . . . . . . . . 90 IntrOduCtiono o o o o o o o o o o o o o o o o o o o o o o o 90 Procedure 0 o o o o o o o o o o o o o o o o o o o o o o o o 90 ReSUItS and DiSCUSSiono o o o o o o .. o o o o o o o o o o o 91 Summary and COHCIHSiOnS o o o o o o o o o o o o o o o o o o 92 The Effects of Feeding Thyroprotein on Lactation and Early Kit GrOWth Performance Of Mink o o o o o o o o o o o o o o o o o o o o 95 IHtrOdUCtiono o o o o o o o o o o o o o o o o o o o o o o o 95 WOCGdUreooo00000000000000.0000... 95 RBSUItS and DiSCUSSiOHo o o o o o o o o o o o o o o o o o o % Summary and COHClUSionS o o o o o o o o o o o o o o o o o o 97 The Effects of High Levels of Antibiotic Upon 102 Kit Mortality Of Mink. o o o o o o o o o o o o o o o o o o o o o 0 Introduction. 0 o o o o o o o o o o o o o o o o o o o o o o 102 Procedure 0 o o o o o o o o o o o o o o o o o o o o o o o o 102 RGSUItS and DiSCUSSiOTlo o o o o o o o o o o o o o o o o o o 103 Summary and Conclusions . . . . . . . . . . . . . . . . . . 103 General DiSCllSSion and. 511mm 0 o o o o o o o o o o o o o o o o o 107 LiteratureCitedoooooooooo00000000000000.112 iv Table No. 10 11 12 13 14 15 LIST OF TABLES Estimate of minimum nutrient requirements for growth and fur development of mink (per pound of moisture- free f00d). o o o o o o o o o o o o o o o o o o o o o o o 0 Composition of control ranch ration - 1956 dry diet StUdieSo o o o o o o o o o o o o o o o o o o o o o o 0 Composition of dry rations - 1956 dry diet growth studies . Proximate analyses of rations - 1956 dry diet growth Study 0 O O O O C O C O C O C C O C C C O O C C Average weights and lengths - 1956 dry diet growth StUdy o o o o o o o o o o o o o o o o o o o o o o o 0 Results of analysis of variance of the weight gains from 11 to 30 weeks - 1956 dry diet growth study. . . Results of analysis of variance of the weight gains 11 to 16 weeks - 1956 dry diet StUdYo o o o o o o o 0 Numerical score of mink pelt grades on November 29, 1956 - 1956 dry diet grOWth Study} 0 o o o o o o o o c or. o o o 0 Composition of rations - 1957 dry diet growth studies . . . Proximate analysis of diets - 1957 dry diet growth study. . Average weights and lengths - 1957 dry diet growth study. . Analysis of variance of male weight gains from 11 weeks of age to November 21 - 1957 dry diet growth study. . Analysis of variance of female weight gains from 11 weeks of age to November 21 - 1957 dry diet growth StUdy o o o o o o o o o o o o o o o o o o o o o o o 0 Analysis of variance of male weight gains from 11 to 16 weeks - 1957 dry diet growth study . . . . . . . . Analysis of variance of female weight gains from 11 to 16 weeks - 1957 dry diet growth study . . . . . . . . Page 16 18 19 20 21 2A 25 27 Table No. Page 16 Analysis of variance of weight gains 16 weeks to November 21 - 1957 dry diet growth StUdy o o o o o o o o o o 31 1? Composition of rations used in 1957 dry diet repro- dUCtionexperimentoooooooooooooooooocoo 31‘" 18 Proximate analysis of rations - 1957 dry diet repro- dUCtiOHStUdyoo00900000000000.0000... 35 19 Female weights and breeding results - 1957 dry diet reprOdUCtionSLUdyoooooooooooooooooocoo36 20 Whelping results - 1957 dry diet reproduction study. . . . . 37 21 Average 1-day and 21-day weights of mink kits - 1957 dry diet reprOdUCtion Stlldy o o o o o o o o o o o o o o 38 22 Analysis of variance of 1-day kit weights - 1957 drydietreproductionstudy....o............ 39 23 Analysis of variance of 21-day weights - 1957 dry dietreprOdUCtiOl’lSLUdyoo0000000000000.coo 1+0 24 Rations for 1958 dry diet reproduction study . . . . . . . . 42 25 Proximate analysis of rations - 1958 dry diet reprOduCtionStl-ldyoooooooooooooocococoo“'3 26 Female weights and breeding results - 1958 dry dietreproductionstudy.................o.M 27 Whelping results - 1958 dry diet reproduction study. . . . . “5 28 Kit weights in grams - 1958 dry diet reproduction study. . . 96 29 Analysis of variance of kits alive at 1-day - 1958 dI'ydietreprOdUCtionStudyooocoooooooooocoo “’7 30 'Weights and weight gains on dry diets in comparison to the control ration - 1957 growth study. . . . . . . . . . 48 31 Estimated caloric values of rations used in some 1956-57gr0w-th5tudiesooooooooooooooooooo51 32 Composition of control ranch ration. . . . . . . . . . . . . 60 33 Composition of semi-purified basal mink ration . . . . . . . 61 3h 'Whole blood prothrombin clotting times of mink after receiving the Specified experimental rations for 28 days . . 62 vi Table No. 35 36 37 38 39 41 #2 43 #5 47 49 50 Whole blood prothrombin clotting times of 9 to 10-day old chicks receiving mink basal, chick basal, and chick basal plus graded levels of menadione sodium bisulfite from hatching time o o o o o o o o o o o o o o o o o o o The effect of terramycin, aureomycin, or sulfa- quinoxaline (SQ) alone and in the presence of vitamin K on whole blood prothrombin clotting times of mink. . . Amino acid composition of mink carcass, mink hair and ration components used - 1958 study. . . . . . . . . Rations used in eXperiments 1 and 2 — 1958 study . . . . Average weight gains or losses of mink. Depletion- repletion experiment No. 1 (Aug. 27 - Sept. #) - 1958 Study 0 O O O O O O O O O O O O O O O O O O O O O 0 Feed consumption per kilo of final body weight per day of mink on repletion portion of experiment No. 1 - 1958 StUdy o o o o o o o o o o o o o o o o o o o o o weights of mink on depletion-repletion experiment NO. 2 (Aug. 27 - Sept. 14) - 1958 Study. 0 o o o o o o 0 Food consumption of mink on repletion portion of experiment NO. 2 - 1958 StUdyo o o o o o o o o o o o o 0 Amino acid content of rations used in experiment N00 3 - 1958 Study 0 o o o o o o o o o o o o o o o o o o Rations used in experiment No. 3 - 1958 study . . .. . . weight gains or losses and food consumption per day in experiment No. 3 - 1958 study . . . . . . . . . . Basal ration for experiment No. 1 - 1959 study . . Amino acid composition of mink carcasses, rations and additions - experiment NO. 1 - 1959 StUdyo o o o o o weights and weight gains of mink on experiment NO. 1 (JUly 13 - Aug. 2) - 1959 StUdyo o o o o o o o o o ‘Weights and weight gains of mink in experiment NO. 2 (Aug. 3 - Aug. 15) - 1959 StUdyo o o o o o o o o o Rations for experiment No. 3 - 1959 study. . . . . . . . vii Page 63 69 7O 71 72 73 74 75 76 80 81 82 83 Table No. Page 51 ‘Weights and weight losses of mink on experiment 85 N0. 3 (Aug. 27 to Sept. 16) - 1959 study 0 o o o o o o o o o 52 Reproductive performance, kit size and mortality - 1958 diethylstilbestrol reproductive experiment. . . . . . . 93 53 Individual performances of mink receiving intermittent doses of stilbestrol after they had implanted but before they had whelped - 1958 diethylstilbestrol reproduction emerimentoooooooooooooooooooooooso 9"" 54 Production of mothers and mortality of kits - thyro- protein, lactation and early kit growth experiment . . . . . 98 55 Average weights of kits in grams - thyroprotein, lactation and early kit growth experiment. . . . . . . . . . 99 56 'Weights and gains in weight in grams of mink on different dietary treatments - thyroprotein, lacta- tion and early kit grOWth experiment 0 o o o o o o o o o o o 100 57 Analysis of variance of 14-day weights - thyroprotein, lactation and early kit growth experiment. . . . . . . . . . 101 58 Production of mothers and mortality of kits - anti- biotic, lactation and early kit growth study . . . . . . . . 104 59 'Weights of kits at one day and 21 days - antibiotic, lactation and early kit growth study . . . . . . . . . . . . 105 60 Analysis of variance of the 21-day weights of kits - antibiotic, lactation and early kit growth study . . . . . . 106 viii LIST OF FIGURES Figure No. Page 1 Calculation of vitamin K content of mink semi-purified basal ration o o o o o o o o o o o o o o o 65 ix Introduction Commercial mink ranching in the United States has developed into a sizeable animal industry during the past four decades. Although mink farming was first attempted commercially in the 1860's, when trappers raised mink from captured wild stock, it was not until the 1920's that mink farming achieved any economic importance (Kellogg, et al., 1954). At that time, mink were overshadowed by the more popular and established silver fox. Since then, fashion trends have shifted from the long-haired fox to the short-furred mink and the latter have been the most desired fur of the past decade. Over five million domestic ranch mink were raised in the United States in 1958, representing an income to ranchers of 106 million dollars (Anon. 1959). The majority were produced in the Upper Lakes region, principally Michigan,‘Wisconsin, Minnesota and Illinois. Michigan has been consistently among the top-ranking states, producing 246,000 pelts valued at $5,156,000 in 1958 (Anon. 1958) and 270,000 pelts valued at $5,260,000 in 1957 (Anon. 1957). In the early days, the principal sources of mink food were horse meat, whole fish and.whole grain cereals. The decline in numbers of horses and the increasing competition for horse meat from pet food manu- facturers has led to extensive use of fresh or frozen packinghouse, poultry and fisheries by-products. There also has been increased use of meat and fish meals, dried distillers solubles, brewers yeasts, and by-products from cereal manufacturing. The use of these feeds, which are of high in- trinsic value but unnatural to mink, has led to many nutritional problems. 1 Mink research has not kept pace with the rapid expansion of the mink industry. This is partly due to the relatively small amount of research being conducted by the industry and public institutions. It also stems from differences between mink and other farm animals which make it difficult to adapt nutritional findings of other species to mink. Through trial and error, ranchers have developed diets upon which mink will grow and produce well. These rations are formulated without know- ledge of the nutrient requirements of mink. Thus, they are not the most efficient nutritionally, the most economical nor do they make maximum.use of ingredients readily available. In many cases, the effects on mink of feed additives, preservatives, and growth promotants which are commonly fed to other species for more efficient husbandry are unknown. Therefore, because of the diversity of the needs of the industry and the desire at Michigan State University to answer pressing questions of applied, as well as fundamental nature, studies have been conducted into several different aspects of mink nutrition. The studies presented in this thesis will be considered under three general categories. The first of these was the develOpment of dry diets for mink. Study I consisted of an evaluation of dry rations compared to ranch- type rations conducted through two growth and two reproductive periods. The second general category of study was the use of semi-purified rations by which diets can be produced containing known amounts of dietary ingredients. Study II was an evaluation of the nutrient requirements of the mink for vitamin K and the effects of certain antibiotics and medica- ments upon blood clotting time. Study III was an attempt to define the amino acid requirements of growing mink. Ranch-type rations containing fish and meat products were used in several practical studies upon effects of feed ingredients and feed addi- tives on the reproductive performance of mink. Study IV evaluated the effect of intermittent feeding of stilbestrol. Study V concerned itself with the effects of feeding thyroprotein, and study VI determined the effects of high level antibiotics upon the lacta- tion and early kit growth performance of mink. General Review of Literature. The purpose of this section is to review what is known of the nutrient requirements of mink and to consider specific characteristics, such as anatomy, rate of food passage and digestibility which might af- fect the nutrition of these animals. Even though it undoubtedly plays an important role, there is no information available on enzyme activity in specific digestive processes in mink. A review of literature pertain- ing to each of the different studies will be reported as these subjects are presented. Anatomy There are no published reports on the histology of the digestive tract of mink and only scattered reports on its gross anatomy. Kainer (1954), in the most comprehensive anatomical study, utilized 77 mink ranging in weight from 400 to 1,450 grams. He described the stomachs as being about 0.5 percent of the body weight and being able to contain from 40 to 70 ml of liquid. The small intestine was divided into a duodenum.with a mean length of 10.6 cm and a jejuno-ileum.with a mean length of 120 cm. The mean pancreas weight was 3.0 gms and the mean liver weight 35.4 gms (4.9 percent of the body weight). No cecum.was present.- The average length of the combined colon, rectum and anus was 10.1 cm. In the above mink, the ratio of intestinal length to body length ranged from 3.60:1 to 4.38:1 with a mean ratio of 3.97:1. 'Wood (1956) reported that in mink ranging from 1.5 to 2.7 lbs., the mean length of intestine was 46.8 in. with a range from 43.5 to 51.0 in. The 4 intestine was about one-half the length of the intestine of the average cat and one-fifth the length of that of the average small dog. From these comparisons, it can be readily seen that the digestive tract of the mink is small in proportion to its body size - even when compared to other carnivores. Digestibility Bernard, Smith and.Maynard (1942), when studying the digestibility of cereals by minke, reported that cooked starch present in wheat, corn and oats was digested 90 percent or more, even when the starch constituted from 45 to 50 percent of the dry matter fed. Raw starch was poorly di- gested (54 Percent). Raw corn meal when composing 20 to 25 percent of the wet'ration was somewhat more digestible (75 Percent), but produced loose feces. Starch fed as folled oats and raw wheat meal was apparently ‘well digested (78 and 93 percent). However, both these products produced a slight scouring. ‘Wheat bran fed as 10 percent of the wet ration depressed the over-all digestibility of the diet, probably due to its laxative efa fect. Fiber in the form of lettuce, carrots or cellOphane did not adversely affect the digestibility of other constituents of the diets. Fats were found to be highly digestible (93 percent). In studies with raw meat products (Smith and Loosli, 1940), di- gestibility of raw meats when fed as 80 percent of the ration was reported as follows: liver 93 percent; horse muscle 86 percent; and spleen 84 percent. Cooking and drying reduced the digestibility to about 72 percent. The protein of soybean meal was found by Ahman (1959) to be 60 percent digestible, cod meal 79, and meat meal 57 percent. He also de- termined that the carbohydrate digestibility of uncooked grains was 65 percent, cooked grains 75 perCent, and the carbohydrate of cooked soybean meal was 57 percent digested. These ingredients were all fed as 30-40 percent of the diet. Leoschke (1960) reported the protein digestibility of horse meat to be 92 percent, chicken entrails 89 percent, chicken heads 78 percent, and chicken feet 52 percent. He believed the lowered digestibility of heads and feet to be related to their high mineral content. Rate of Food Passage Food passage in mink is very rapid.when compared to that in other species. The appearance of feed in the feces 6 hours after ingestion 'was reported by Bernard gtflgl. (1942) and complete elimination within 15 hours after ingestion was reported by Loosli and Smith (1940). ‘Wood (1956) reported the rate of food passage as varying from 1% to 2 hours in starved mink. Nutritive Requirements What is known of the nutritive requirements of mink was summarized in a National Research Council bulletin (1953). The results of this com- pilation plus what has been learned of the nutrient requirements since that time are listed in table 1. These, then, are the known nutritional characteristics of this unusual "domestic" animal about which so little is known and.which offers so many challenges of a nutritional nature. Table 1. Estimate of minimnn nutrient requirements for growth and fur development of mink (per pound of moisture—free food). Unit Anomrt Protein 7.23 wks. of age 22 Bassett £1; £1; (1951A) 23+wks. of age 16 " I " " " Vitamin A I.U. 780 NRC" Vitamin D‘ 0"".I Bassett _e_i; _a_l_. (19518) Vitamin E I.U. 12 Stowe _e_t_ §_J_._. (1960) Vitamin K meg < 6.5 Travis _e_t 31. (1961) Thiamine 11g 0.5 Leo schke (1959) Riboflavin mg 0.9 NRC Pantothenic acid mg 3.6 NRC Niacin ng 4.5 NRC Pyridoxine mg 0.5 NRC Folic acid mg 0.09 NRC Vitamin 312 mg 4 Leoschke g3; _a_2|_... (1953) Salt 0.5 NRC Calcium % 0.4 NRC Phosphorus 3% 0.4 NRC Ca:P ratio 1:1 Bassett gt 1.1. (19513) Energy for maintenance per pound body weight 124 Hodson and Smith (1942) * NRC estimates of National Research Comcil, Publication 296 (1953) ** Diet of natural feedstuffs was found adequate without added vitamin D General Materials and.Methods Animals Mink used in these studies came from three sources. The dark mink used in the 1956, 1957 and 1958 studies consisted of progeny of mink originally donated by mink breeders of the state and progeny of mink obtained from Kellogg Feed Research Project in 1953. In 1957, 40 female and 10 male sapphire mink were purchased from Mr. Charles Wilbur of Traverse City, Michigan, with 20 sapphire female mink being added in 1958. In 1958, 40 female and 10 male dark mink were obtained from Mr. Rudy Menzel, Glendale, Michigan. These mink were uniform with better than average pelt quality and comprise the nucleus from which came the current mink herd. However, since the principle of randomization for experimental treatments is incompatible with the principle of preserving the better animals for breeding, there has been some deterioration in pelt quality from that of the original animals. To maintain quality in an experimental mink herd, either there must be a periodic infusion of good quality commercial animals or about one-third of the herd must be segregated from use as experimental animals and maintained as a breeding herd. Part of the progeny from.this segregated herd.may be used for experiment and part should be used to perpetuate the breeding herd. Housing and Management The animals were confined in individual covered pens of uniform size. Each pen was equipped with a water cup, feed door and nest box. Animals fed dry diets during freezing weather were assured of adequate water supplies by an electrically heated.watering system which was turned on periodically by a time clock. Management methods were similar to those of a well-run commercial ranch. Animals were fed twice daily starting in May when the young were born and continuing throughout the summer. They were fed once daily during the fall, winter and spring. 'Weights and measurements were taken periodically, the intervals between measurements depending on the type of experiment. Evaluation of ReSponse ReSponse to dietary treatments was evaluated primarily in terms of body weight. Length gains and pelt quality were also used to measure differences, but because of the difficulty of gathering uniform data were given less consideration. Number of females whelping, litter size, weights and kit mortality were used in the reproduction studies. Observations were made on mortality, general health and appearance of all animals. ‘Where pertinent, casualty animals were necropsied and the cause of death determined. Standard statistical methods were employed. Data were analyzed by analysis of variance (Snedecor, 1956) and the differences between groups were determined by Duncan's multiple range and multiple F tests (Duncan, 1955). In an effort to adjust kit weights to litter size, the largest and most homogeneous group of kits (1957 fat reproduction study) was analyzed to determine the relationship between birth weight of individual kits and the size of the litter. A straight line was fitted to the data (201 male and 176 female initial weights and 189 and 165 female 21-day 10 weights). It was found that the slopes of these lines were not significantly different from zero. This means that in this population the litter size did not significantly influence the initial or the 21-day weights of the offspring. Correlation coefficients for males and females between litter size and offspring at 1- and 21 days were also run and in both cases it ‘was found that the correlation coefficients were not significantly dif- ferent from zero. From these calculations, it was concluded that for purposes of these analyses, size of litter was not compensated for and analyses of variance were run on 1-day and 14-day or 21-day weights in all reproduc- tion tests. Although it was not statistically significant, there was a tendency for the animals of larger litters to be smaller and it is possible that with larger numbers of kits a straight line relationship between litter size and kit size might be demonstrated. It is also possible that there is some biological explanation for the lack of correlation, such as smaller litters of 1, 2 and 3 coming from biologically weaker animals. The data available were insufficient to determine this. Studies of 2 z Diets Introduction Fresh meat and fish ingredients which currently comprise from 65 to 85 percent of the commercial mink ration have the disadvantages of seasonal shortages and gluts and also the need for refrigeration. Costs of transportation are high since up to 80 percent of the fresh material is water. The dangers of spoilage and feed poisoning such as botulism are ever present. Costs of refrigeration equipment and labor for food mixing are also high. The elimination of the need for using fresh or frozen animal products would lead to greatly improved efficiency of mink production. Success has been achieved in feeding completely dry foods to other carnivores such as the fox and dog, so it is not inconceivable that satis- factory dry rations for mink could be developed. The ultimate in dry diet foods would be dry pellets which would give optimum nutrition during all phases of the life cycle. However, any information that leads to the use of dry rations during any portion of the life cycle or that leads to increased use of dry ingredients is of great economic importance to the mink rancher. For these reasons, investigations on dry diets have been conducted by the Michigan State University Fur Animal project since 1948. The work being reported here is a continuation of the investigations conducted by Drs. Schaible and Kifer from 1952 to 1956. Review of Literature The principal studies on dry diets for mink reported in the literature have come from the Michigan State University Fur Animal Project. Travis 23,31. (1949) reported on the initial attempt to for- mulate a completely dry ration for mink. Feed trials with six adult and 15 kit mink showed that the diet employed was inadequate for promot- ing optimum growth in young mink started on experiment at 10 to 12 weeks of age, but did appear to maintain body weight in adults over a period of 111 days. The primary defect of the diet was shown to be concerned with protein, particularly one or more of the amino acids, methionine, lysine and/or tryptophan. Howell (1952), in a continuation of this work, reported limited progress. Growth and reproduction were subnormal in animals fed solely on dry rations. This was believed to be a protein rather than a vitamin deficiency. Methionine, lysine and tryptophan apparently were not involved. Both Travis and Howell believed palatability and digestibility to be limiting factors in the successful use of their experimental rations. Kifer (1956) and Kifer and Schaible (1955a, 1955b, 1956) demon- strated further improvements in the dry-type ration. They obtained in- creased growth and reproductive responses by pelleting and by adding fat to the rations. Palatability was not a factor under the conditions of their experiments. 'While performance was comparable during maintenance, results were not equal to those obtained on typical ranch rations during the reproductive cycle or during lactation and early growth. Gunn (1960a) conducted an interesting experiment in which he fed to growing mink a dehydrated ration composed of the identical ingredients as the fresh meat control diet. The dehydration was carried out in a 12 13 steam-jacketed drier at 2500 F. with one atmosphere of vacuum. Growth performance and feed consumption were poorer in this group than in the mink receiving the control ranch ration. Gunn (1960b) believes that the experiment might have succeeded if the prepared complete wet ration could have been dried in a vacuum-freeze drier. The research reported here consists of two growth and two repro- duction studies. The performance of mink on the dry rations was compared to that of mink on a typical ranch ration which consisted principally of fresh meat and fish products (Table 2). Growth Studies - 1956 These studies were conducted with a total of 180 kit dark mink allocated to nine treatments consisting of 10 males and 10 females in each group. Dry rations used were modifications of the most successful of the 1955 growth rations. Diet 1 was the control ranch ration. Diets 2, 3 and 4 were designed to test different fat levels and were fed as a .meal to which water was added to produce a hamburger-like consistency. Diet 2 was comparable to the best dry ration of the 1955 studies (ration 55-6) and contained 12 percent fat. Diets 3 and 4 had yellow grease added to produce diets of 16 and 20 percent fat, respectively. Diets 5 through 9 were fed as pellets (3/16-inch in diameter and averaging 3/8—inch long). Diet 5 contained 12 percent fat, the added fat consisting of yellow grease. Diets 6 and 7 compared torula and brewers dried.yeasts, respectively. Diet 8 contained no yeast, the dif- ference being made up by fish meal and soybean oil meal. Diet 9 was identical to Diet 2 but in pellet rather than meal form. l4 Mink were placed on experiment when they were 11 weeks old and weight and length measurements were taken when they were 11, 16 and 30 'weeks of age, representing approximately 60, 80 and 100 percent of their final body weight, reapectively. Body length measurements were deter- mined by stretching the mink on a ruler and measuring the distance from the tip of nose to the base of the tail. Experimental rations, their chemical analysis and the performance of the animals on different rations are shown in tables 2 through 8. Analysis of variance of the weight gains from 11 to 30 weeks shown in table 6 indicate that mink on diet 1 grew significantly better than mink on diets 2, 5 and 7 but not significantly better than mink on the other experimental rations. From the results of this analysis, it was decided to analyze the gains from 11 to 16 weeks and from 16 to 30 weeks to determine where the greatest difference in the experimental treatments occurred. Results of analysis of variance and multiple range and multiple “F” tests of the weight gains from 11 to 16 weeks are shown in table 7. Comparison among lots of this test show the mink receiving the control ranch ration to have had a growth rate significantly greater than those on any of the dry rations. Among the dry diets at this period, weight gains of mink of lots 8 and 9 are significantly greater than those of mink in lot 5. Analysis of variance of the weight gains from 16 to 30 weeks did not demonstrate a significant difference in the rations. Analysis of variance of length gains did not show a significant difference in length gains due to dietary treatment. An attempt was made to evaluate the pelt quality of 5 males and 5 females from each of the different experimental rations. Table 8 shows 15 the results of such an evaluation. An analysis of variance did not demonstrate any difference that could be attributed to different dietary treatments. Thus, the control ration was shown to be superior to the dry rations during the period from 11 to 16 weeks, with the weight gains of the mink on dry diets being comparable to the controls from 16 to 29 weeks. Significant differences between treatments in length or in pelt quality were not demonstrated. Growth Studies - 1957 During the summer and fall of 1957, an effort was made to further improve those dry diets that were most effective when fed during the growth period in 1956., Since improved responses were achieved by in- creasing the fat level, it was decided to test 20 percent and 28 percent fat levels. These levels are in the average and high range of commercial ranch rations, reapectively. The effects of adding 25 percent fresh liver to the dry ration were also determined. The objectives of this addition were twofold. The first was to determine if there were nutrients in fresh liver which would.make the performance of mink on dry diets comp parable to that of those on typical ranch rations. If liver, a rich source of high quality protein, vitamins and unknown nutritional factors, did improve the performance, then by determining what was in the liver that improved the performance, it could be determined what was deficient in the dry diets. The second objective was to improve, if possible, the performance of the dry rations by a rather simple addition to the point where they would be comparable in performance to typical ranch rations. This would be of immediate practical value to commercial ranchers. One hundred and fifty kit dark mink were used in this experiment (15 males and 15 females per treatment). Mink were placed on experiment 16 Table 2. Composition of control ranch ration .- 1956 dry diet studies Imredient % ibrse meat 26.7 Ocean fish 26.7 Liver 500 Cereal mix, supplanentedl 15.0 Total 100.0 1 Mink cereal. mix 1001. Kellogg Compam', Battle Creek, Michigan 1? Table 3. Composition of dry rations -- 1956 dry diet growth studies Ingredient L2 3 L» gathné 7 8 9 Cereal m1 17.7 17.7 17.7 17.7 17.7 17.7 17.7 17.7 Dried yeast, torula 7.5 7.5 7.5 7.5 15.0 - - - - 7.5 Dried yeast, brewers 7.5 7.5 7.5 7.5 - - 15.0 - - 7.5 Soybean 011 meal. 50% 20.0 20.0 20.0 20.0 20.0 20.0 25.0 20.0 Fish mea‘Lz. 55% 20.0 20.0 20.0 20.0 20.0 20.0 25.0 20.0 Herring mea13, 70% 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 Meat scraps, 65% 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 Liver product" 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 Dried skim milk 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0 Cottonseed oil 6.0 - - - - - - 6.0 6.0 6.0 6.0 No. 2 yellow grease — - 11.0 16.0 6.0 - - - - - - - - Vits. E and 312 supp.“5 .85 .85 .85 .85 .85 .85 .85 .85 Vit. B couple): supp.6 - - .. - .. - - - .. - .. .. 0.2 .. .. mum-auto» Mink mix 1007, Kellogg Company, Battle Creek, Mich. Vitaproil, Maine Marine Products, Inc.. Portland. 146. Maine Marine Products, Inc.. Portland, Me. RitaliVer, Imperial Products Co., Wadsworth, I11. Vitamin 13 (20.000 IU/lb) 23 gms., 1312 Fortafeed 21490, Lederle Laboratories, Pearl River, New York supplement (6 rug/lb) 363 gms. Table 0. Proximate analyses of ration - 1956 dry diet growth study (76) Diet H20 Prot. Fat Fiber N .F.E. Ash Ca P M Control 68.2 13.2 6.6 0.8 8.6 2.7 .08 .39 56-2 9.3 02.1 13.1 1.9 23.0 10.3 1.70 1.39 56.3 6.9 39.5 17.7 1.8 20.5 9.6 1.58 1.30 56-0 7.2 37.0 22.2 1.6 22.8 ’ 8.8 1.33 1.15 56-5 9.0 01.9 12.6 1.8 20.9 9.8 1.05 1.26 56.6 9.8 01.1 12.7 1.9 20.9 9.9 1.50 1.28 56-7 9.3 01.3 12.6 1.7 25.6 9.6 1.31 1.26 56.8 9.0 03.0 13.8 1.0 21.5 10.9 1.70 1.36 56-9 9.5 01.1 - 12.7 2.0 25.1 9.6 1.02 1.26 Moisture—free basis Control - 01.5 20.6 2.0 27.1 8.0 1.51 1.22 56-2 .. 06.3 10.0 2.1 25.7 11.3 1.91 1.53 56.3 - 02.3 19.0 1.9 26.2 10.3 1.69 1.39 56-0 .. 00.0 20.0 1.7 20.7 9.5 1.00 1.20 56-5 - 06.1 13.9 2.0 27.0 10.8 1.60 1.39 56.6 .. 05.6 10.1 2.1 27.7 11.0 1.66 1.02 56-7 .. 05.0 13.8 1.8 28.2 10.5 1.00 1.39 56.8 .. 07.7 15.2 1.5 23.7 12.0 1.91 1.03 56.9 - 05.2 10.0 2.2 27.6 10.6 1.56 1.39 19 Table 5. Average weights and lengths -. 1956 dry diet growth study __.£5£.___£_____W ht in rams W 11 wk. 16 wk. Nov. 21 11 wk. Nov. 21 Lot 1 - Males Control 908 1297 1506 13.5 16.3 Fanales 638 800 927 , 12.0 10.0 Average 773 1070 1236 12.9 15.3 Lot 2 - Males 1% meal 902 1092 1%3 13.8 16.3 Females 653 729 829 12 .5 10.2 Average 778 910 1006 13.2 15.2 Lot 3 - Males 163?: meal 915 1151 1390 13.6 16.3 Averag e 788 9‘03 1130 13 .0 15 o 0 Lot 0 - Males 20% meal 92]. 1201 1088 13.5 16.6 Fanfles 605 676 797 12.0 10.2 Average 783 938 1102 13.0 15.0 Lot 5 .. Males 12% pellet, 899 1008 1273 13.6 16.2 Females animal fat 668 716 805 12.6 10.1 Average 780 882 1039 13 .1 15.2 Lot 6 - Males 12% pellet, 895 1090 1330 13.5 16.1 Females torula yeast 620 700 752 12.2 10. Average 760 897 1002 12.9 15.1 Lot 7 .. Males 125 pellet, 927 1100 1295 13.6 16.2 Females brewers yeast 603 697 793 12.0 10.2 Average 785 898 1000 13.0 15.2 Lot 8 - Males 12% pellet, 907 1201 1000 13.8 16.0 Fanales soy 632 731 803 12.5 10.0 Lot 9 - Males 1% pellet, 922 1158 1386 13.8 15.8 Females dry control 618 738 805 12.3 10.2 Averag e 770 908 1116 13 .1 15 . O 20 Table 6. Results of analysis of variance of the weight gains from 11 to 30 weeks —- 1956 dry diet growth study Source Degrees of of Mean F mugs variation freedom square Calculated P = 0.05 P = 0.01 Total 179 63.216 Sea: 1 29.09? 172.8“ 3.80 6.63 Diet 8 068.7 2.75” 1.90 2.51 S x D 8 288 1.68 1.90 2.51 Error 162 17007 n Significant (P < 0.01) Comparison amorg lots at 1 percent level of probability Lot 2 5 7 6 9 3 8 0 1 Av. wt. gains (ng) 220 231 205 276 290 292 296 319 380 Table 7. Results of analysis of variance of the weight gains 11 to 16 weeks -- 1956 dry diet study Source Degrees of of Mean F values variation freedom square Calculated P = 0.05 P = 0.01 Total 179 Sex 1 9.68“ 16805** 3084 6063 Diet 8 638.9 11.9""ll 1.90 2.51 mmr 162 570% *1! Significant (P 0.01) Comparison among lots at 1 percent level of probability Int 5 7 2 6 3 0 8 9 1 Av. wt. gains (gms) 98 110 133 137 156 156 176 178 298 Table 8. Numerical score"I of mink pelt grades on November 29, 1956 -- 1956 dry diet growth study lot 1 2 3 0 5 6 ‘7 8 L Fresh Meal. Pellets 13 Tor— Brew- Soy 12% 16% 20% An. ula ers ' oil Con- Control Fat Fat Fat fat yeast yeast meal trol Males 6 6 0 8 6 0 6 8 0 8 6 6 6 6 8 0 8 6 6 6 6 2 6 6 2 6 6 8 8 8 2 6 6 2 6 8 8 8 2 0 6 10 6 10 6 Total 36 30 26 22 3O 30 20 38 30 Females 8 8 8 6 8 2 8 8 6 8 8 6 10 8 0 6 10 8 6 2 8 6 8 6 6 8 6 0 2 6 2 0 6 2 8 0 0 2 0 0 8 2 8 6 0 Total 30 22 32 28 36 20 3O 00 28 Males and females Total 66 56 58 50 66 50 50 78 58 * Mink graded on over-all quality in relation to each other. Highest possible score 12, lowest 0. Size and condition (fatness or thinness) not considered. Pelts graded by Mr. Joseph Stuekerjuergen, Madison, Wisconsin. 23 when they were 11 weeks old and weights and length measurements were taken at 11 weeks, 16 weeks and on November 21. November 21 was used as a final weigh data in 1957 due to unseasonably cold weather which would have caused irregular weights if the animals had been carried to the 29-week weighing. The control ranch ration consisted of horse meat, tripe, ocean whiting, liver and cereal as previously shown in table 2. Water was added to the dry diets to attain a hamburger-like consistency. Experimental rations, their chemical analyses and the performance of the animals on different rations are shown in tables 9 through 16. Analysis of variance of the weight gains from 11 weeks of age to November 21 showed a significant interaction (P C 0.01) between sex and diet, in that the males on high performance diets gained much more pro- portionally than the females on high performance diets. For this reason, the weight gains were analyzed by sexes in order to obtain the maximum information available from the data. Table 12 shows the results of the analysis of variance of the male gains. At the one percent level of probability, lot 1 was better than lots 2, 0 and 5, lot 3 was better than lots 2 and 0, and lot 5 was better than lot 0. At the 5 percent level of probability the mink on the fresh meat control gained significantly more than all other diets, and the mink that received the dry diet with fresh liver gained significantly more than those that did not receive the liver. In the case of the females (table 13), analysis of variance gain showed the mink on the control ranch ration to have the greatest gains. In this case, the gains of controls were not significantly greater than those on the dry diets plus liver, but the gains of the control were 20 Table 9. Composition of rations -. 1957 dry diet growth studies Ra_t_i.9_n lrgredient 57-6 57-7" 57-8 57.9* Cereal mix1 10.66 10.66 10.66 10.66 Dried yeast, torula 5 5 5 5 Dried yeast, brewers 5 5 5 5 Soybean oil meal, 50% 15 15 15 15 Fish mealZ. 55% 30 30 30 30 Liver product3 3 3 Skim milk powder 0 0 0 0 Sucrose 0 0 .. .. Corn starch 0 0 .. .. Vitamins" .30 .30 .30 .30 Choice white grease __lj___ _l.j__ _23___ _2_3___ Total 100.0 100.0 100.0 100.0 "' 25% fresh liver added In Per 100 pounds: Vit A (10,000 USP/gm) 12 gms; vit. D (3,000 IU/gm) 6 gms; Vit E (20,000 IU/gn) 6 gms; v11: K Menadione (8.6 gm/lb) 22 gms and choline Cl (25%) 110 gms. .1, Kellogg Mink mix 1007 3 Vitaproil - Maine Marine Products, Inc. Ritaliver - Imperial Products Co. 25 Table 10. Proximate analysis of diets .. 1957 dry diet growth study (6) Diet H20 Prot. Fat Fiber N.F.E. Ash Ca P "As fed“ 1 72.8 11.5 5.0 .62 7.2 2.5 .58 .39 2 09.2 20.0 11.9 .90 13.7 0.3 .72 .61 3 55.2 18.7 10.0 .70 12.0 3.5 .50 .50 0 09.0 19.0 16.2 .91 10.3 0.2 .66 .59 5 57.0 17.2 13.3 .75 7.9 3.0 .09 .09 Moisture-free basis 1 - 02.2 19.7 2.3 26.6 9.1 2.13 1.03 2 - 39.3 23.0 1.8 27.0 8.5 1.02 1.20 3 .. 01.8 22.2 1.6 26.6 7.8 1.20 1.20 0 - 38.0 31.8 1.8 20.2 8.2 1.29 1.16 5 - 00.0 31.3 1.8 18.5 8.0 1.15 1.15 Table 11. Average weights and lengths -— 1957 dry diet growth study Weight in grams ngth in inches Ill—wk . 16.-wk . Nov. 21 ll-wk. Nov. 21 Lot 1 — Males Control 951 1306 1569 10.5 16.3 Females 700 886 909 13.0 10.0 Average 828 1116 1239 13.9 15.3 let 2 - Males Dry, 20% fat 979 1075 1285 10.5 15.9 Females 698 723 813 13 .0 10.3 Average 839 899 1009 10.0 15.1 Lot 3 .. Males Dry, 20% fat + 980 1179 1091 10. 5 16.2 Females 25,8 liver 687 702 855 - 13 .3 10.2 Average 836 961 1173 13.9 15.2 Lot 0 .. Males Dry, 283 fat 987 1118 1270 10.0 15.7 Females 688 712 802 13 . 2 13 .9 AV erag e 838 915 103 8 13 08 1"" o 8 Lot 5 .. Males Dry, 28% fat + 959 1101 1389 10.3 15.7 Females 25% liver 705 777 907 13.4 14-3 Average 832 959 1108 13.9 15.0 Table 12. Analysis of variance of male weight gains from 11 weeks of age to November 21 - 1957 dry diet growth study Source Degrees of of Mean F vilues __ variation freedom square Calculated P = 0.05 P = 0.01 Total 70 Diet 0 5037.8 30.96“ 2.53 3.65 finer 70 155.5 ** Significant (P {0.01) Comparison among lots at the 1 percent level of probability Lot 0 2 5 3 1 Av. wt. gain (gms) 287 306 030 507 618 Comparison among lots at the 5 percent level of probability Lot 0 2 5 3 1 Av. wt. gain (gms) 287 306 030 507 618 28 Table 13. Analysis of variance of female weight gains from 11 weeks of age to November 21 -- 1957 dry diet growth study Source Degrees of of Mean F values fl variation freedom square Calculated P = 0.05 P = 0.01 Total ‘ 70. Diet 0 317.0 0.20” 2.53 3.65 Ermr 70 75036 ** Significant (P< 0.01) Comparison among lots at the 1 percent level of probability Lot 0 2 3 5 1 Av. wt. gain (gms) 110 115 168 202 209 Comparison among lots at the 5 percent level of probability Lot 0 2 3 5 1 Av. wt. gain (gms) 110 115 168 202 209 Table 10. Analysis of variance of male weight gains from ll to 16 weeks .. 1957 dry diet growth study Source Degrees of of Mean F values variation fieedom square Calculated P = 0.05 P = 0.01 Total 70 Diet 0 1987.8 327.6" 2.53 365 Error 70 60.68 u Significant (P (0.01) Comparison among lots at the 1 percent level of probability Lot 2 0 5 3 1 Av. wt. gain (gms) 96 131 182 195 395 30 Table 15. Analysis of variance of female weight gains from ll to 16 weeks ...... 1957 dry diet growth study Source Degrees of of Mean F values variation freedom square Calculated P = 0.05 P = 0.01 Total 70 Diet 0 673.0 20.0" 2.53 3.65 Error 70 28.00 ** Significant (P < 0.01) Comparison among lots at the 1 percent level of probability Lot 2 0 3 5 1 Av. wt. gain (gms) 25 25 55 72 186 31 Table 16. Analysis of variance of weight gains 16 weeks to Nov. 21 -- 1957 dry diet growth study Source Degrees of of Mean F [aléles v_ variation freedom squares Calculated P = 0.05 P = 0.01 Total 109 Sex 1 7,590 51.25IMI 3.80 6.63 Diet 0 003 .2 2.99“ 2.37 3 .32 'S x D 0 255.0 1.72 2.37 3.32 Error 100 108.1 u Significant (P( 0.01) Comparison among lots at the 5 percent level of probability Lot 1 0 2 5 3 Av. wt. gain (gms) 123 123 150 189 212 32 significantly greater than those of the females receiving the dry diets without added liver. In order to determine if the greater differences appeared in the period from.11 to 16 weeks, or from.16 weeks to November 21, an analysis of variance was run on the gains during these periods. In the former interval, there again was a highly significant interaction between sex and diet, and because of this the analyses of variances were run separ- ately for each sex. Results are shown in tables 10 and 15. Mink on the control diets did best, those on dry diets with liver, next best and mink on the dry diets without liver gained the poorest. Analysis of variance of weight gains from 16 weeks to November 21 (table 16) shows a reversal, with mink on the meat control gaining the least, mink on the dry diets plus liver gaining the most, and.wink on the dry diets without liver in an intermediate position. This apparently is due to the fact that mink on the control ration had achieved most of their weight by 16 weeks, while those on the dry diets, being smaller, were still growing and compensating for their poorer earlier gains. Reproduction Studies - 1957 During 1957, a trial was conducted comparing the reproductive performance of mink receiving the control ranch-type ration to that of mink feed a dry ration during winter maintenance, and supplemented with 25 percent fresh liver during gestation, parturition, and lactation. Twenty dark female mink were fed the control ration and 15 dark and 5 pastel females were fed the dry diets. The experiment was initiated January 18th and continued until the kits were 21 days old. The addition of fresh liver was started.on.March 11. ‘water was added to the dry diets to make a mixture of hamburger-like consistency. 33 Experimental rations, their chemical analyses and the performance of the animals are shown in tables 17 through 23. Table 19 indicates that there was no significant difference in adult weights or breeding performance on the different treatments. Tables 20 and 21 show the number of kits whelped to be comparable with a slightly higher mortality and slightly smaller kit weights at 21 days of age for those on the dry diet plus liver. In table 22 the analysis of variance of the initial weights indicate a significant difference between sexes but not between diets. Table 23 shows a.highly significant difference (P < 0.01) between sexes and.between diets. From this, it can be concluded that the production and initial weights of mink on the dry diets + 25 percent fresh liver was not significantly different from the controls, but that the 21-day weights of the kits from.mothers on the dry diet with liver were significantly lower (P < 0.01). Reproduction Studies - 1958 Since the dry diets plus fresh liver gave good results during gestation and lactation in 1957, it was decided to attempt to feed com- plete dry rations during gestation, and to supplement them with fresh animal products during the lactation period only. During lactation, the dry diets were fed in two ways - with 25 percent liver or 25 percent trips. The objective of this work was to determine whether the beneficial effects observed in 1957 were due to the nutrient effects of liver or to added palatability furnished by fresh animal products. Control mink re- ceived the ranch-type ration of table 20 throughout the experiment. Ten dark females were allocated to each of the three treatments. The experiment was started on January 21, 1958 and continued until the 30 Table 17. Composition of rations used in 1957 dry diet reproduction experiment Control diet ‘70 Dry diet 7’. Horse meat %.7 Cereal mix2 17.2 Tripe 26.6 Soybean oil meal (50%) 19.0 Ocean perch 26.7 Dried yeast, torula 7.2 Liver 5.0 Dried yeast, brewers 7.2 Cereali, supplemented 15.0 Fish meal3 (55%) 19.0 Total 1005 Herring meal" (70%) 9.6 Meat scraps 0.8 Liver product5 2.8 Skim milk powder 2.8 Choice white grease 10.0 Vitamin A and D suppl. * Total 100.0 . Vitamins added/100 lbs. feed: Vit. A (10,000 IU/gm) 8 gms; Vit. 03 (1.500 III/gm) 80 gms. Kellogg mink mix No. 1001 Kellogg mink mix No. 1007 Vitaproil .. Maine Marine Products, Inc. Maine Marine Products, Inc. Ritaliver - Imperial Products Co. “#UNH 35 Table 18. Proximate analysis of rations—- 1957 dry diet reproduction study (%) Diet H20 Prot. Fat Fiber Ca P "As fed“ Control 72.!" 12.1 6 03 o 7 057 o “’1 Dry diet + 25% liver 60.8 20.2 7.0 .7 .06 .52 Moisture-free basis Control - 03.5 22.8 2.5 2.06 1.08 Dry diet + 257’. liver - 51.6 19.0 1.7 1.17 1.33 36 .5” N...“ am...” «men 9.. area." + soaps.“ b5 $4 2...... ma no.3?" E as on SA on; HA on Honaeoo aunts. no.3 .2. .36 d” .32 3 .92. moaned.“ smooch . oz . oz Sense: 62 heron soapoanondon scan he an? .... noasnon meanness use assess cameos .3 cards 37 m6 m5 we we no .8 3 S neared he in ms 3 an mm as ea on Hanson nodes. and... cook a hassle new H EB saddens sadness caste and fleece and graduates as read. noun 62 case and» 62 .oz and H a .a need... 33.. I heat doaeoaooadnn 83 be $3 .. nfianoa madness .8 .33 38 Table 21. Average l-day and 21.day weights of mink kits .. 1957 dry diet reproduction study liday weightsjgms) 21.-d we hts 3 Male Fenale Av. Male Female Av. Control Dry ration + liver 10 .5 9.9 10.2 111 105 108 10.2 9.0 9.8 100 90 95 Table 22. Analysis of variance of 1-day kit weights -— 1957 dry diet reproduction study -; fl.— Source Degrees at of Mean F values variation freedom square Calculated P = 0.05 P = 0.01 Total 173 Sex 1 0’49 70 2*. 3 0 8n 6 .63 Diet 1 .16 2.3 3.80 6.63 S x D l .23 3.0 3.80 6.63 Error 170 .068 ** Significant (P < 0.01) Table 23. Analysis of variance of 21.-day weights -. 1957 dry diet reproduction study Source Degrees of of Mean F valyes variation fi‘eedom square Calculated P = 0.0 5 P = 0.01 Total 162 Sea: 1 62 13.41“ 3.84 6.63 Diet 1 169 25.76"“ 3.8“ 6.63 Error 159 M62 u Significant (P< 0.01) kl kits were 14 days old. Starting on April 25th (about 5 days before the first litter was expected to arrive), the animals were changed to their respective diets containing tripe or liver. These rations were continued to the end of the trial. ‘water was added to the dry diets to make a mix- ture of hamburger-like consistency. Formulation of the rations, their chemical analyses, breeding results and.whelping results are given in tables 24 to 29. Table 29 illustrates the extreme difficulty of demonstrating sig- nificant differences between the production of two experimental groups with small numbers of females. Table 27 shows that there was an average difference of 2.6 kits per litter per female kept or 1.2 kits per female that whelped between the females receiving the control diet and those receiving the dry diet containing liver. However, even this large dif- ference in the number of kits per female kept could not be demonstrated to be significantly different, although the "F" value in this case came very close to being significant at the 5 percent level. Analysis of variance of the 1-day and 14-day'weights did not show a significant difference between treatments. Discussion A summary of certain relationships between ranch rations, dry diets and dry diets plus liver taken from the 1957 growth study is shown in table 30. Since there was no significant difference between the fat levels, the two groups on dry diets alone and supplemented with liver were separately averaged. At the end of the experiment, both.males and females fed the dry diet weighed substantially less than those on the control diet. 'When 1&2 Table 21+. Rations for 1958 dry diet reproduction study Control 7» Dry ration % Horse meat 26.? Cereal mix2 17.7 Tripe 26.6 Dried yeast, torula 7.5 Ocean fish 26.? Dried yeast, brewers 7.5 Liver 5.0 Soybean oil meal, 50% 15.0 Cereal mix, supplemented1 15.0 Fish mea13. 55% 30.0 Liver product“, 3.0 Total 100.0 Skim milk powder MO Vitamins“ .3 Choice white grease 15.0 Total 100.0 n Vitamins added per 100 lbs. feed: Vit. A (10.000 USP/gm) 12.0 gms; Vitamin (3.000 IU/gm) 6.0 gms; Vit. E (20,000 IU/gm) 6.0 gms; Vit. K ( enadione 8.6 gms/lb) 22.0 gms and choline chloride (25%) 110.0 ngo Kellogg mink mix No. 1001 Kellogg mink mix No. 1007 Vitaproil .. Maine Marine Products, Inc. Ritaliver .. Imperial Products Co. {rump 43 Table 25. Proximate analysis of rations —. 19 58 dry diet reproduction study (fi) Diet I120 Prot. Fat Fiber N.F.E. Ash Ca P "As fed": 001113101 7306 11.3 600 07 6o“ 202 O50 '35 Dry ration* 8024‘ 35.3 214'.“ 1.9 22.1 800 10a 1015 Dry + 25% tripe 63A 15.8 10.1 .7 6.9 3.0 .42 .hz Dry + 25% liver 60.6 17.8 10.1 .7 7.5 3.2 .144 .’+9 Moisture-free basis: Control .. 42.2 22.7 2.5 21+.2 8.4 1.90 1.33 Dry ration — 38.5 fioé 2.0 24.1 807 1032 1025 Dry + 25% tripe .. 43.1» 27.7 1.8 18.9 8.2 1.16 1.16 Dry 4» 25% liver .. as“? 25.6 1.7 19.2 8.2 1.12 1.21» * Analyzed before water added 3 S at. won one on g a 3 new mam 8o 3 H828 menses 8.3 on do: n .oom m :3. modest.“ gonads anode." .oz 62 any page: 62 known coapospadon neat but 39” II madame.“ 936095 use magma?» oafifih 6N Danna 45’ €23 note “8&2: noon: the onomoo abet m odors am fine: Bede nooflon be woven nee. abogmdmdsm .n ad 5.: mm as S on m 3 onus a3 + and as nun 3 mm mm on N. S .833 awn + «in o.n o.a .. .i on an 3 on 1.5 m6 Qm 2 mm an no 3 3 H8930 8323 seen a name i be a BB nodded: e328 333 323 nod cameo.“ nod finite: Me a an as? and" on new? 3.4x. no.2 and” page .02 .oz been eoateeondon pone he need .... madame.“ madden; .dm Soon. Table 28. Kit weights in grams -- 1958 dry diet reproduction study Ration At 1 day Hale Female Av. At lhgdgys Hale Female Av. Control Dry'+ 25% liver Dry + 23% tripe 8.8 8.5 8.6 8.6 7.6 8.1 8.“ 706 800 53 58 55 57 53 55 54 53 54 47 Table 29. Analysis of variance of kits alive at l-daqr .. 1958 dry diet reproduction study Source Degrees of of Mean F values variation freedom square Calculated P = 0.05 P = 0.01 Total 29 Diets 2 17 JP 3.22 ' 3.33 5.12 Error 27 5.14 mm m2" own HS” in so am 5m 0% admin on no: and 8m 3 an mm 93H «.3 odd: €0de mmm + node and mm 3...” an em ma am an new. new onward 3 RN mm and am :3 mm 83 Se ode: «not? in 8H mom 09” mm 8a 8H 2: mom ooh edged 8H 98 8a mmm 03 non 8H mom.“ Hum oats 50.3.30 as as one an as H828 e582 Haoeoo e582 Hobdoo 9588 325:8 :t. :5 no a no a «o a no a.“ an Henna team He. .eozui: in do. .roszWNH .5. 3.3:. 3 :t. 3 refine... 5 22o _ names H38 seat snag» $9 In £3..va Honpsoo 23 3 comanmdsoo 5 avoid but so nfiww #3303 use mpsmdoz . om manna “9 the dry diet was supplemented with liver, growth was intermediate between the other two diets. Females, however, did better proportionately than the males on the dry diet, alone and with liver. To analyze how the growth occurred, the gains were evaluated for the two periods shown. From 11 to 16 weeks, weight gain on the dry diets was poor compared to that on the control with males gaining more than females on a percent- age basis. During the period from 16 weeks to November 21 both males and females did better than during the earlier period when compared to the controls. The females gained four to five times as much as those on the control ration. Over-all, the absolute gain of the males on the dry diets was greater than that of the females but the rate of growth of the females was proportionately better than that of the males when compared to the controls. It is possible that the difference between performance of the controls and the animals on dry rations is due to need for adjustment of the animals to the dry diets. This took a week to ten days and, of course, did not occur with mink on the control diet. It is possible that the animals on dry rations were unable to regain the weight lost during this adjusting period. Because of this, the increased response to the dry rations during the second period may have been due either to compen- satory growth or to less critical nutritional demands at that time. To decide this point, it would have been necessary to start additional mink on dry diets at 16 weeks of age. A question which has never been adequately answered, and which is pertinent to this study, is the animal's reaction to growth retardation. In many species slower gains in early stages of growth are compensated for by increased gains later in the growth period. However, unpublished 50 work by the author and colleagues at Ithaca, New Ybrk, shows that the epiphyses of the long bones close at about 16 weeks of age in the mink, which would preclude any further gains in length. If so, requirements for late growth should be less critical. This may help eXplain why dry diets did well during this period. The significance of fat deposition in the growing mink also needs further clarification. Adult mink have a cycle of gradual fat deposition during the fall and.winter and gradual loss of fat during late winter and Spring. Much of the weight gain in kit mink after 16 weeks of age is fat. Whether fat is necessary for optimum pelt deve10pment, or whether an ex- cess or an insufficiency of fat depositions can cause damage to the pelt, has never been adequately determined. In the 1958 reproduction study, analysis of variance did not show a significant difference in 1-day or 1#-day kit weights between the dif- ferent diets. The litter size may have been a factor. At 1# days, mothers on the control ranch ration were nursing an average of 5.5 kits, mothers on the dry'diet plus liver were nursing #.1 kits, and those on the dry ration plus tripe, #.6 kits. Kifer (1956) indicated that a limiting factor in the dry diets in his studies was digestible energy, as he obtained greater growth responses with higher fat levels. To investigate this possibility, the digestible energy values of the ranch-type rations and several of the dry rations containing different fat levels were calculated as shown in table 31. Nutrient digestibility was assumed as follows: for the dry rations - protein 70 percent, N.F.E. 80 percent and fat 90 percent; for the ranch rations - protein 85 percent, N.F.E. 90 percent and fat 90 percent. Crude fiber was ignored as it probably approaches zero. Energy values were Table 31. Estimated caloric values of rations used in some 1956—57 growth studies Actual % Dig estible fat in Total calories calories Ration ration per lb. per 100 gms. per 100 gms. 1956 Control 20.6 2088 £460 405 1957 Control 19.7 2056 ' 453 399 1956 12% fat meal 14.1; 1898 418 328 1956 16% fat meal 18.6 2016 w.» 356 1956 20% fat meal 2L».0 2161 C76 386 1957 20% fat meal 23A 2157 #75 385 1957 20% fat meal + 25% 22.2 2152 #74 382 liver 1957 28% fat meal 31.8 2356 519 429 1957 28% fat meal + 25% 31.3 2347 517 426 liver 52 calculated on a basis of nine calories per gram for fat and four calories per gram for protein and carbohydrate. Table 31 shows that the higher fat-dry diets used in the 1957 growth studies contained comparable levels of digestible calories to the control ranch-type rations. Since performance was not as good for the males on dry diets as for those on dry diets plus liver, and for the latter with respect to the ranch-type rations, it might indicate that there is a factor present in fresh food necessary to obtain maximum re- sponse from dry rations. However, some investigators (Travis, 1949; Howell, 1952; Gunn, 1960a) have reported less food consumption by mink on dry rations than by those on control rations. ‘Whether this is due to smaller animals needing to eat less, or whether the animals were smaller because they ate less, has never been determined. So far, no digestibility studies have been published on dry rations. A combined study of rate of food consumption and digestibility should be conducted to determine the cause and effect of the poorer growth of male mink on dry rations. Since the females did better than the males on the dry diet alone, and on the dry diet supplemented with liver, it would seem that either females do not need as much of the fresh food factor or they consume more of the dry feed in relation to their total weight. Thus, it is possible that dry rations will be developed for females before they are attained for males. Length and weight help to characterize growth but the attribute of greatest economic importance in mink is pelt quality. Evaluations based on subjective judgments used exclusively by fur graders leave much to be desired. Objective methods have been developed (wentz and Hunt, 1951; Dolnick, 1959) but they are so time-consuming that they are impractical 53 for routine use. In general, if a diet produces better growth than another, it usually also produces at least as good and possibly a better pelt. In fact, many of the problems in mink nutrition are in such an early stage of study that growth responses are probably also indices of the relative values of the treatment insofar as they affect pelt quality. This is believed to be true in the case of the current dry diet studies. At least, there was no indication that dry diets had detrimental effects on pelt quality. Summary and Conclusions Experiments were conducted with mink during two growth and two reproductive periods to find out if dry rations could perform as well as fresh ranch-type rations. A total of 739 mink were used in these trials: 9 groups of 20 mink in 1956 and 5 groups of 30 mink in 1957 in the growth studies; #0 adults and 188 kits in 1957 and 30 adults and 151 kits in 1958 in the reproduction studies. Dry rations were fed in the form of pellets or meal moistened to hamburger-like consistency. Brewers yeast and torula.yeast gave comparable results when constituting 15 percent of this ration. Increasing the fat level from 12 to 20 percent in the dry rations improved the rate of growth of kits. No added beneficial effect was ap- parent from increasing the fat to 28 percent. In certain growth trials, sex x diet interactions were evident; males gave a greater resPonse to changes in diet than females. The dry diet gave somewhat inferior growth compared to the control ranch ration. From 16 to 30 weeks of age, dry diets produced comparable or greater gains than the control. 54 There was no significant difference in fur quality or length gains of the live mink among the diet treatments. Adult mink fed dry diets during the winter, and dry diets with 25 percent of fresh liver during breeding, gestation and lactation, were com- parable in adult weights, breeding performance and number of kits whelped to mink that received a typical commercial ranch ration. There was no significant difference in 1-day kit weights, but 21-day weights were in favor of the control ranch ration. There was a significant sex difference in both 1-day and 21-day kit weights in favor of the males. Mink given dry rations through winter maintenance, breeding and gestation until April 25th, and then given dry diets with 25 percent liver or tripe averaged over four kits per female kept. This performance, while about equal to the national average, was not as good as that of the con- trols (5.9) which was exceptional. The response to the dry diets from adding fresh liver or fresh tripe was similar, indicating that the value of the fresh products may be due to palatability rather than nutrient value. Vitamin K Studies Introduction Most mammals obtain part of their vitamin K requirements from synthesis by their own intestinal bacterial flora. However, the anato- mical and physiological limitations of the mink leave doubt as to its ability to obtain sufficient vitamin K in this manner. The digestive tract is only four times the body length, there is no caecum, and the relatively undifferentiated large intestine is only about one-third of the body length (Kainen 1954). Food passage is rapid, averaging less than two hours in mink with empty digestive tracts and slightly more than two hours when food is continuously available (wood, 1956). Thus, the conditions for bacterial synthesis in the gut would appear more limited in mink than in most mammals. It has also been established that some mink containing the Aleutian genes for color (aa) have an unexplained bleeding from the mouth and digestive tract (Helmboldt and Jungher, 1958) which could be associated with a deranged blood clotting mechanism. This study was, therefore, initiated for the following reasons: (1) to determine if mink require a dietary source of vitamin K; (2) to observe what effects certain antibiotics and medicaments would have upon blood clotting time; and (3) to compare the whole blood prothrombin time of dark mink to that of mink containing the Aleutian genes (aa) for color. 55 56 Procedure The procedure followed was to place the animals on the experimental ration for a period sufficient to deplete their body stores of vitamin K, and then to evaluate the effects of vitamin K in the ration by observing the increase in prothrombin clotting times. The method of determination was the whole blood prothrombin clot- ting time as modified by Frost gt‘gl. (1956), using lyophilized extracts as the source of thrombOplastin. To obtain more uniform results, animals were bled by heart puncture using siliconized needles, tubes and syringes. Mink were housed individually in conventional outdoor pens of 1 x 1-inch wire mesh with aluminum feeders and waterers. Chicks used in the biological assay of the basal mink ration for vitamin K were raised in electrically-heated batteries with a wire floor mesh of 1/3 x 1/3-inch. In order to prevent possible coprophagy and/or bacterial synthesis, the pens, feeders and waterers of the mink and chicks were cleaned daily and the purified rations were kept refrigerated until fed. Data were sub- jected to analyses of variance, multiple range and multiple F tests. Results and Discussion In the first experiment 30 female sapphire (homozygous for the Aleutian gene) and 30 female dark mink were used. Ten dark and 10 sapphire mink were placed on each of the following treatments: (1) control ranch ration (table 32); (2) basal semi-purified mink ration with no added vitamin K (table 33); and (3) (basal semi-purified mink ration plus 7 grams of menadione sodium bisulfite per ton of feed. After 28 days, the whole blood prothrombin clotting times were obtained.with the results shown in table 34. 57 These data show that there were no significant differences in whole blood prothrombin times due to treatment or genetic strain. Three mink receiving the purified ration without added K were continued for two additional weeks with no appreciable increase in clotting time; their average clotting times being 17.3 seconds at the end of four weeks and 18.3 seconds at the end of six weeks. It is evident, therefore, that mink require no more vitamin K than was present in the control ration. To ascertain this value, a chick assay test was conducted on the semi-purified ration which had been fed to the mink. A total of 100 male Single Comb‘White Leghorn chicks were allocated equally to the following: lot 1, the mink semi- purified basal ration; lot 2, vitamin Kpfree assay ration (Quick, 1957); and lots 3, h and 5, vitamin K-free assay ration plus 22.5, 90 and 360 milligrams of menadione sodium bisulfite per ton, reSpectively. Using the method of Almquist and Klose (1939) of plotting mean reciprocal prothrombin times against the logarithms of the vitamin K dosage, this test showed that the semi-purified ration fed the mink con- tained 13 milligrams of menadione sodium bisulfite activity per ton (chart 1). This demonstrates that adult mink need less vitamin K than 13 milligrams per ton of feed, air dry basis. A level as low as this would be virtually impossible to attain in a practical ranch ration. In another phase of the investigation, the effects of certain medicaments and drugs upon blood clotting time were studied. ‘Where sulfaquinoxaline was fed to mink as a coccidiostat, it upset the normal 'blood clotting process and caused severe hemorrhages in many cases (Hartsough and Gorham, 1960). Since sulfaquinoxaline affects the bacterial flora of the gut so that vitamin K is not produced (Kornberg, gt‘gl., 58 1944), aureomycin and terramycin which are also used in mink therapy were investigated. Results of this study are shown in table 36. It can be seen that terramycin or aureomycin at levels of 400 grams per ton did not significantly increase blood clotting time. Sulfa— quinoxaline at levels of 0.05 percent or more significantly increased clotting time. .Menadione sodium.bisulfite fed at a level of 10 grams per ton decreased the clotting time when administered in the presence of 0.06 percent sulfaquinoxaline, but did not lower it to the normal range. Menadione sodium bisulfite fed at the rate of one gram per ton did not significantly decrease blood clotting time in the presence of 0.05 percent sulfaquinoxaline. In preliminary studies, levels of sulfa- quinoxaline of 0.1 percent or more caused death by cardiac tamponade in about one-half of the mink from which blood was drawn by heart puncture. Summary and Conclusions Experiments were conducted to ascertain (1) if normal adult mink require vitamin K; (2) whether dark mink differ in this respect from sapphire mink which contain the Aleutian gene; (3) if sulfaquinoxaline or certain antibiotics affect blood clotting time. The dietary requirement of normal adult mink was established as being less than 13 milligrams per ton of menadione sodium.bisulfite or 6.5 micrograms per pound of feed. Practical ranch rations would contain much higher levels. The whole blood prothrombin times of the sapphire mink tested (16.8 1_.4 seconds) were similar to those of normal dark mink (17.8;: .4 seconds). 59 Sulfaquinoxaline fed for 6 to 8 days at the 0.05 percent level or higher significantly increased the whole blood prothrombin clotting times. Vitamin K fed at levels of 10 grams per ton reduced the clotting time of mink fed sulfaquinoxaline at a level of .06 percent. Addition of aureomycin and terramycin at a level of 400 grams per ton did not significantly increase whole blood prothrombin times when fed for 6 or 8 days. Mink fed a semi-purified ration had comparable blood clotting times to those fed a typical ranch ration. 60 Table 32. Composition of control ranch ration* Irgredient Percentages Horse meat 26.7 Ocean whiting 26.6 Beef tripe 26.7 Liver 5.0 Cereal mix, supplemented1 15.0 Total 10000 *Sufficient water added to make a hamburger—like consistency 1 Mink cereal mix 1001, Kellogg Company 61 Table 33. Composition of semi—purified basal mink ration“ Irgredient Percentages Vitamin-free casein 32 Stripped lard1 l4 Cod liver oil 1 Cellulose2 Salts3 l4, Choline chloride (70%) 1 Sucrose 43 Total 100 Donated by Distillation Products Industries, Rochester, N. Y. Solka-Floc, Brown Compamr Phillips and Hart (l935),oobalt chloride 0.005 percent added Water added to produce a thick syrup consistency for mink. Ration fed dry to chicks. *UNH Vitamin and amino acid per 100 grams of feed added at the expense of sucrose. Mfllgg' rams Mil ' rams Arginine HCl 500.0 Para aminobenzoic acid 100.0 Methionine 300.0 Folic acid 0.2 Thiamine HCl 0.5 Biotin 0.05 Pyridoxine HCl 0.5 Alpha tocopherol 8.0 Riboflavin 1.0 Vitamin B12 0.015 Nicotinic acid 5.0 BHT 20.0 Ca pantothenic acid 3.6 I-inositol 50.0 62 Table 34. Whole blood prothrombin clotting times of mink after receiving the specified experimental rations for 28 days _‘-_ _-: - ‘- ——-' ;— Mean clotting Type time in seconds of No. with standard Rations mink mink error Control ranch Dark 10 17.8 1 .36 Sapphire 10 16.8 i 01"2 Semi—purified without Dark 10 18.1 -_|-_ .37 vitamin K Sapphire 10 17.2 1; .28 Semi-purified plus Dark 10 17.4 i .33 7 gms. per ton vitamin K Sapphire 10 17.6 i .43 63 Table 35. Whole blood prothrombin clotting times of 9 to 10.day old chicks receiving mink basal, chick basal, and chick basal plus graded levels of menadione sodium bisulfite from hatching time Ration 1. chicks Whole blood prothrombin clotting time in seconds with standard error Mink semi—purified basal Vitamin Kpfree chick basal Chick basal + 22.5 mg/ton’ Chick basal + 90 ng/ton Chick basal + 360 mg/ton 10 10 10 10 10 67.5 1; 6.8 93.9 i 9.4 53.0 1 5.6 26.5 :5 1.5 22.1 1 1.1 64 Table 36. The effect of terramycin, aureomycin, or sulfaquinoxaline (SQ) alone and in the presence of vitamin K on whole blood prothrombin clotting times of mink Whole blood pro thrombin clotting No. Days time in seconds with Lot Ration mink on exp. standard error 1 Mink ranch diet 20 8.9 18.9 1 .15 2 Terramycin #00 gms/ton 10 8-9 19.6 1 .27 3 Aureomycin 400 gms/ton 10 8-9 19.3 _-|; .35 1+ so 0.05% 10 8-9 21.6 1 1.02 5 SQ 0.06% 10 8-9 26.6 1 3.0 6 50 0.05% + vitamin K 10 8-9 21.2 1 .98 (l gin/ton) 7 SQ 0.06% + vitamin K 10 8-9 21.2 1 .83 (10 gms/ton) Comparisons of means by analysis of variance and Duncan's multiple range and multiple F tests (P 0.01). Lot 1 3 2 6 7 4 5 Mean 18.9 19.3 19 06 2102 2102 2.106 26.6 Figure 1. Determination of vitamin K (menadione sodium bisulfite) concentration of the mink semi-purified basal ration. Log of vitamin K concentration plotted against reciprocal of whole blood prothrombin clotting time. 65 .000... m0 ZOP mud MPEJDQm EDEOW wZO_O< assoc obHHm .ps .sd code no anon oodaosz monsom has among noossz oeoo snom . one» sees .oz .oz obese auoso one ocean Neo H we peas Honeneoaaeeaaseoao whoa eaeo as be seam nsosanogwo obwposUOpdon Honenobaasnasssoao wood II seaaeenos one mean one .oosegsoenoa seasosoonaom .mm oases 94 Table 53. Individual performances of mink receiving intermittent doses of diethylstilbestrol after they had implanted but before they had whelped -. 1958 diethylstilbestrol reproduction experiment Total Kits Kits Date kits born alive Female whelp born alive 14 days Control: 024 4/ 30 8 6 6 D160 5/9 7 7 7 D620 5/6 5 4 4 D752 5/3 5 5 5 D800 5/6 5 5 5 0836 5/ 2 4 4 4 150 mcgs. per dose: D280 5/3 6 5 2 D32 5/ 2 7 7 7 D230 - .. D340 5/12 3 0 0 D812 - D802 5/ 2 6 4 0 300 megs. per dose: D224 5/ 7 1 o o D352 - "‘ D372 5/ 7 1 0 0 D83o 5/6 3 2 o 0o150 5/3 7 6 6 * Mummified kits. found on necropsy 6/ 5 Effect of Feeding Thyroprotein on Lactation And Early Kit Growth Performance of Mink Introduction The period of parturition and lactation is recognized as the time of greatest nutritional importance for female mink breeders. For kits, greatest stress and kit mortality occurs during early growth.when they are nursing their mothers. Thus, any practice that would improve per- formance during these periods would be very valuable to the mink industry. Recently, it has been reported that thyroprotein improves lacta- tion performance in cattle and swine under certain conditions. Conse- quently, it was decided to study the effects of thyroprotein in the diet of female breeders prior to and after whelping. By this addition, it was hoped to improve the milk output of the mothers and thus improve the growth rate of the kits. Procedure In the Spring of 1958, the experiment was initiated using 30 dark adult female mink, 15 per group. The experiment was designed so that there were five control animals and five treated mink on each of three different diets containing 20 percent, 30 percent and 40 percent fat, reSpectively. The 20 percent fat diet contained 26 2/3 percent each of horse meat, tripe and ocean perch, 15 percent Kellogg 1001 cereal and 5 percent liver. Animal grease was added at the expense of the ration to produce the diets high in fat. 95 96 Previous studies by Reineke, §t_al. (1960) evaluated thyroxine secretion rate and the thyroactive iodinated casein utilization in mink and thus made it possible to use a level of iodinated casein that was within the physiological range of the mink. Starting on April 28th, 2.5 m1. of a suspension containing 24 milligrams of thyroprotein mixed into 125 grams of food was fed daily to each treated group of five mink. This was given and consumed in the morning before the mink were allowed further food. This gave a dosage of 0.53 mg. of thyroactive iodinated casein (1.0 percent thyroxine) per 100 grams of body weight per day which is twice the amount needed to be equivalent to the thyroxine secretion rate of adult male mink in April. Performance of the females and their young is shown in tables 54 through 57- Results and Discussion ‘Whelping results and weights at one and 14 days are given in tables 54 and 55. Analysis of variance of the one-day weights showed no significant differences between treatments. Likewise, there was no difference that could be attributed to the differences in dietary fat levels. Table 57 shows the analysis of variance of 14—day weights which indicates that the treated group weighed less than the control; this was apparent at the one percent level of significance. The thyroprotein treated group was also lower in the one-day weights. However, because the kits were not identified at 1 day of age, it was impossible to run an analysis of co-variance to determine if the 14—day weights were re- lated to the 1-day weights. 97 In considering kit weights, it is necessary to remember that the mother supplies the environment and nutrition of from one to 8 or more kits. This exerts a confounding influence upon the analyses of the kit weights, particularly when there is as small a number as 15 mothers per group. Further, the experiment was run with only one level of thyro- protein, which might not have been the dose to produce optimum results at this period. Summary and Conclusions Thyroprotein was given to 15 mink mothers at a level of 0.53 mg. per hundred grams of body weight per day of thyroactive iodinated casein (1.0 percent thyroxine) starting about five days before the first litter was expected to be born and was continued until the young were two weeks old. Fifteen breeder females and their young were used as controls. There appeared to be no effect upon number of kits born or inci- dence of mortality of the young. Kits from the treated.mothers were non-significantly smaller at the 1-day weighings but significantly smaller at the 14—day weighing. However, due to the relatively small numbers of mothers involved and the variable number of kits per litter, the experiment should be repeated before definite conclusions can be made as to the beneficial or harmful effects of adding therprotein at this level during this period. 98 Table 54. Production of mothers and mortality of kits _— Thyroprotein, lactation and early kit growth experiment Number Total N0. kits No. kits Number that no. kits born alive at Lot females whelped born alive 14 days Control 15 14 99 90 71 Treated 15 15 104 96 72 99 Table 55. Average weights of kits in grams .. Thyroprotein, lactation and early kit growth experiment At 1 day At 14 days Lot Male Female Av. Male Female Av. COntI'Ol 903 806 900 61.2 5605 5809 Treatai 806 8.2 8.4 55.8 54.0 54.9 100 «.mm 2% 93 mm To do so om 3 oak min Know om do 2. :5 mm on 9mm 9mm o.Hm me To so to we om sea a "unpacks 1mm dam mom mm do on do on 3 w.mm o.mn m.:o mm w.m 0.0 n.0H :N on s.wm «.mm m.om um o.w N.w m.m mm om see c «Honpooo . >¢ odesom ode: oases . >4 oflesom odes clad: ohm swoops was 3 3 do see a 2 .oz pcosamogxo mesonw pox hapmo one commenced .CfiopOAQOhhna II oncogenes... anemone pcouommwo :0 Claims no usenm so #3303 S.” modem one mango: .wm eased. 101 Table 57. Analysis of variance of l4—day weights —— Thyroprotein, lactation and early kit growth experiment Degrees of Mean F values Source freedom Square Calculated P = 0.05 P = 0.01 Total 144 28.79 Sex 1 9.77 6.78** 3.84 6.63 Treatment 1 16 .61 11.53“ 3 .84 6 . 63 S X T 1 2.41 1.67 3.84 6.63 Error 141 1.44 ** (P< 0.01) Theggffect of High Levels of Antibiotic Upon Mortality_and Early Kit Growth of Mink Introduction In most mammals that produce litters, a substantial mortality occurs in the young during the first few days of life. Mink are no exception as they may have a mortality of from 5 to 30 percent or more, most of which occurs during the first three days of life. Thus, any practice that will increase the viability of young will greatly increase the efficiency and reduce the cost of production per animal. Broad spectrum antibiotics have been shown to improve the growth responses of weanling mink (Warner Einél- 1956) and to improve the environment of other species (Libby and Schaible, 1955). Thus, it was desired to see if an antibiotic might improve the growth and livability of newborn mink. Procedure In the springs of 1956 and 1957 there were placed respectively 20 and 40 mothers on the control ration and 25 and 39 mothers on the same ration plus terramycin. In 1956, the control ration (table 2) was the regular ranch diet. In 1957, half of the females in each group received the control ration and half received this ration with three percent fat added as choice white grease. Chlortetracycline was fed to the mothers at a level of 400 grams per ton of food starting a few days before whelp- ing and continuing until the mink kits were three weeks old. 102 103 The results on reproduction, kit mortality and 1- and 21-day kit weights are shown in the accompanying tables. Results and Discussion Analyses of variance were conducted on the 1-day and 21-day weights for both years. There were no significant differences in either of the 1956 weights or for the 1-day weights in 1957. However, the 21-day weights in 1957 showed a significant difference in treatments at the five percent level of probability in favor of the controls. Summary and Conclusions During 1956 and 1957 terramycin was used at high levels in an attempt to reduce kit mortality and to improve growth of young mink during their first three weeks of life. Forty-five adult female dark mink were used the first year and 79 the second year. These mothers produced 217 and 442 kits, respectively. There was no difference in kit production or mortality that could be attributed to the antibiotic treatment. The birth weights of the kits whose mothers received terramycin were comparable during 1956; in 1957, kits from the control animals were significantly greater in weight than those from the treated group at the five percent level of probability. These results demonstrate that there was no beneficial effect and a possibility of harmful effects from the addition of terramycin to the ration at levels of 400 grams per ton during this period. 104 Table 58. Production of mothers and mortality of kits -- Antibiotic, lactation and early kit growth study At 1 day' At 14 days No. loss No . No . that No . born dead 7.? No . alive ,8 females whelped alive or died loss alive 1 day' loss 1956: Control 20 17 97 4 4.1 89 4 4.5 Terramycin 25 21 113 3 2.6 103 7 6.8 1957: Control 40 36 197 6 4.6 179 12 6.7 Terramycin 39 36 219 20 9.1 173 26 15.03 105 Table 59. Heights of kits at one day and 21 days .. Antibiotic, lactation and early kit growth study l-day weights 21-day weights Male Female Av . Male Female Av. 19 56 : CODtI'Ol 10 .1 9.3 907 110 06 95.5 103.0 Terramycin 909 9.3 906 109 .0 98 .3 103 06 1957: Control 907 902 9.4 112.4 lOloLl' 106.9 Terramycin 9.5 8.8 9.2 107.4 99.9 103.6 106 Table 60. Analysis of variance of the 21-day weights of kits in 1957 -- Antibiotic, lactation and early kit growth study Degrees of Mean F values Source freedom square Calculated P = 0.05 P = 0.01 Total 350 99.19 Sex 1 85.56 41.13 3.84 6.63 Treatment 1 10.56 5.05** 3.84 6.63 S X T l 3.07 1.47 3.84 6.63 Error 347 2.09 ** (P< 0.01) General Discussion and Summary The experiments previously discussed represent a three-fold ap- proach to the solution of some important problems of mink nutrition, namely the use of ranch-type rations, semi-purified diets and dry diets. The least complex studies are those involving the use of ranch-type ra- tions containing fresh animal products. Research of this type is neces- sary to obtain information of more immediate and practical value to the feeder. A. Studies using ranch-type rations were conducted during the re- productive cycle to determine the possible beneficial effects of high level antibiotics and thyroid-active compounds during lacta- tion and early kit growth, and to determine the possible harmful effects of intermittent dosages of stilbestrol during this period. 1. Oxytetracycline (terramycin) was fed at levels of 400 grams per ton of feed during two lactation and early kit growth sea- sons. There was no beneficial effect in kit production, growth or mortality that could be attributed to the antibiotic treat- ment. At 21 days of age the body weights of kits from mothers which received the antibiotics were significantly lower than the body weight of the control kits. 2. Thyroprotein was fed to fifteen mother mink at levels of 0.53 milligrams per 100 grams of body weight (one percent thyro- active iodinated casein) starting about five days before the first litter was to be expected and continued until the young were two weeks of age. This treatment had no effect on the 107 B. 3. 108 number of kits born or the incidence of mortality of the young. Kits from treated mothers were significantly smaller at 14 days of age. In another experiment, diethylstilbestrol was fed intermittently beginning after implantation and continuing through late ges- tation, whelping and early kit growth. Results indicated an almost complete failure of reproductive processes - embryo re- absorption, lowered kit production, lowered kit weights and greater kit mortality were observed. The development of dry diets for mink presented a more complex problem to the nutritionist due to the use of feeds in a form unnatural to the mink. 1. Studies on dry diets containing no fresh animal products, or dry diets supplemented with fresh liver or fresh tripe were carried through two growth and two reproduction periods. The dry diets resulted in a somewhat inferior growth rate compared with the ranch ration during the period from 11 weeks to 30 weeks of age, and growth was much poorer, especially during the period from 11 to 16 weeks. However, from 16 weeks to 30 weeks, the gains of mink on dry diets was as great or greater than those on ranch rations. The growth response of mink fed dry diets which were supplemented with 25 percent fresh liver were intermediate between those on the ranch ration and those on dry diets. There were no significant differences in animal length gains among mink on the different dietary treatments. Increasing the fat level from 12 to 20 percent in the dry ra- tions improved the growth of kits. No beneficial effect was 3. 109 apparent from increasing the fat to 28 percent. The response of the males to changes in diets was greater than that of the females. Adult mink fed dry diets during winter maintenance and dry diets with 25 percent of fresh liver during breeding, gestation and lactation, were comparable in adult weight, breeding per- formance and number of kits whelped, to mink that received a typical commercial ranch ration. However, 21-day-old kit weight of the controls was greater. The reSponse from adding fresh liver or fresh tripe during lactation and early kit growth was similar which indicated that the value of the fresh animal products may be due to palatability rather than nutrient value. Dry diets would have many obvious advantages, but successful adaptation awaits greater nutritional knowledge of the require- ments of mink. Some progress has been achieved in this direc- tion. However, much work still remains to be done. It is almost certain that successful dry rations for all phases of the life cycle in mink will ultimately be achieved. It is possible that a solution to dry rations will be attained by an entirely different approach than those currently used. Likely possibilities include: (a) an intensive investigation of di- gestibility and palatability; (b) studies on the use of enzymes to increase utilization of dry feeds; (c) studies on nutrients or nutritional factors which may be destroyed by the drying processes and which need to be replaced; and (d) studies on the possibility of strain differences, all of which should be taken into account. C. 110 The third approach used in these investigations was the use of semi-purified diets. This is the only possible approach to cer- tain types of nutritional studies as it is the only means by which known and controllable amounts of certain ingredients can be fed. 1. Experiments were conducted using semi-purified diets to ascer- tain: (a) if adult mink require dietary vitamin K; (b) whether dark mink differ in this reSpect from sapphire mink; and (c) if sulfaquinoxaline or certain antibiotics affect blood clotting time. The dietary requirement of normal adult mink was estab- lished as being less than 13 milligrams of menadione sodium bisulfite per ton of feed. Sulfaquinoxaline fed for six to eight days at the 0.5 percent level or higher significantly increased whole blood prothrombin clotting times, while the addition of aureomycin or terramycin at levels of 400 grams per ton did not significantly increase clotting times. 2. During two growing seasons, experiments were conducted to de- termine the protein and amino acid requirements for growing mink. Depletion-repletion and growth study techniques were applied with partial success. Growing mink maintained their weight for short periods on semi-purified diets containing;15 percent protein and 20 percent fat when supplemented with appro- priate amino acids. Other factors, probably cystine and methionine, appeared to be limiting the growth of the mink on the experimental rations used. In conclusion, it may be stated that by using the above tech- niques, advances in the knowledge of mink nutrition were made in specific areas. The limitations of knowledge and procedures 111 were also defined and by these means, the groundwork has been laid for further advances in the relatively undeveloped field of mink nutrition. Literature Cited Ahman, 0., 1959. Digestibility experiments with mink. Vara Palsdjur (1 :4. Almquist, H. J., and A. A. Klose, 1939. Determination of the anti- hemorrhagic vitamin. Biochem. J. 33:1055. Anon., 1959, 1958, 1957. Statistical report on the American fur farm industry. National Board of Fur Farming Organizations, Milwaukee, Wis. Bassett, C. F., L. E. Harris, L. M. Llewellyn and J. K. Loosli, 1951A. The protein requirement of growing minks. Unpub. data. U.S. Bur. Anim. Ind. and Cornell Univ., Ithaca, N.Y. Bassett, C. F., L. E. Harris and C. F.‘Wilke., 1951B. Effect of various levels of calcium, phosphorus and vitamin D intake on bone growth. II. Mink. J. Nutrition 44:433. Bernard, R., S. E. Smith and.L. A. Maynard, 1942. Digestion of cereals of mink and foxes with Special reference to starch and crude fiber. Cornell Vet. 32:29. Cannon, P. R., E. M. Humphreys, R.'W. Wissler and L. E. Frazier, 1944. Chemical, clinical and immunological studies on the products of human plasma fractionation. XXIII. The effects of feeding possible blood substitutes on serum protein regeneration and weight recovery in the hypoproteinemic rat. J. Clin. Invest. 23:601. Dolnick, E. H., 1959. Histogenisis of hair in the mink and its rela- tionship to diemal fetal fat cells. J. of Morphology. 105(1):1. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics. 11:10 Gunn, C. K., 1960A. Dehydrated mink ration tests during growth and furring season. Nat. Fur News 32(8):10. Gunn, C. K., 1960B. Personal communication. Frost, D. V., H. S. Perdue and H. C. Spruth, 1956. Vitamin K activity of menadione sodium bisulfite in chickens. J. Nutrition 59:181. Hartsough, G. R., and J. R. Gorham, 1960. Sanitation and health. The Blue Book of Fur Farming, Editorial Service Co., Milwaukee,‘Wis. Helmboldt, C. F., and E. L. Jungherr, 1958. The pathology of Aleutian disease in mink. Am. J. of Vet. Res., 19:212. 112 113 Hodson, A. Z., and S. E. Smith, 1942. An estimate of the maintenance energy required by foxes and minks. Amer. Nat. Fur and Market J. 20 9 :10. Howell, R. E., 1952. A nutritional study of ranch—raised mink. Unpub. M.S. thesis. Michigan State College. Kainer, R. A., 1954. The gross anatomy of the digestive system of the mink. ADI. J. or Vet. Res., 15:82. Kellogg, Co E0, C. F. Bassett and R. K. EnderSo 1951+. Mink raiSing, U. S. Dept. of Agriculture Circular 801. Kifer, P. E., and P. J. Schaible, 1955A. Dry diets for ranch-raised mink. I. Suitability for late growth and maintenance. Mich. Agr. EXP. Sta. Quart. B1110 37:592. Kifer, P. B., and P. J. Schaible, 1955B. Dry diets for ranch-raised mink. II. Effect on breeding, whelping and early growth of kits. Mich. Agr. Exp. Quart. Bul. 38:192. Kifer, P. B., 1956. Successful dry rations for use during the late growth, maintenance, and reproductive periods of ranch-raised mink. Unpub. M.S. thesis. Michigan State University. Kifer, P. E., and P. J. Schaible, 1956. Further developments in formu- lating dry rations for mink. Mich. Agr. Exp. Sta. Quart. Bul. 39:17. . Kornberg, A., F. S. Daft and W. H. Sebrell, 1944. Mechanism of produc- tion of vitamin K deficiency in rats by sulfonamides. J. Biol. Chem., 155:193. Libby, D. A., and P. J. Schaible, 1955. Observations on growth responses to antibiotics and arsonic acids in poultry feeds. Science, 121:733. Leoschke, w. L., R. J. Lalor and c. A. Elvehjem, 1953. The vitamin B12 requirement of mink. Jour. Nutrition, 49:541. Leoschke,'w. L., and C. A. Elvehjem, 1959A. The importance of arginine and methionine for the growth and fur development of mink fed purified diets. J. Nutrition, 69:147. Leoschke, W} L., and C. A. Elvehjem, 1959B. The thiamine requirement of the mink for growth and fur development. J. Nutrition, 69:211. Leoschke, W., 1960. The digestibility of animal proteins by mink. Nat. Fur News, 32(4):37. Loosli, J. K., and S. E. Smith, 1940. Nutritional experiments with foxes and mink. Am. Fur Breeder, 12(7):6. 114 Mitchell, H. H., and A. A. Albanese, 1950. Protein and amino acid re- quirements of mammals. Academic press, New Yerk. Moustgaard, J., and P. M. Riis, 1957. On the protein requirements for fetal growth and the biological value of proteins in mink. Nat. Fur News, 29(10):15. National Research Council, 1953. Nutrient requirements for domestic animals. VII. Nutrient requirements for foxes and minks. Publ. 29 . Phillips, P. H., and E. B. Hart, 1935. The effect of organic dietary constituents upon chronic fluorine toxicosis in the rat. J. Biol. Chem., 109:657. Quick, A. J., 1957. Hemorrhagic diseases. Lea and Febiger, Philadelphia, Pa. Reineke, E. P., H. F. Travis and P. E. Kifer, 1960. Thyroidal iodine131 turnover, thyroxine secretion rate, and thyroactive iodinated casein utilization in mink (mustela vison). Am. J. of Vet. Res. 21:862. Snedecor, G. H., 1956. Statistical methods, fifth edition. Iowa.State College Press, Ames, Ia. ‘ Smith, S. E., and J. K. Loosli, 1940. Some nutritional studies on mink. Nat. Fur News, 12(4):10. Stowe, H. D., C. K. Whitehair and H. Travis, 1960. Pathology of the vitamin E deficiency in the mink. Fed. Proc., 19:420. Travis, H. F., R. E. Howell, A. C. Groschke and C. G. Card, 1949. Mink feeging experiments. Report 1. Mich. Agr. Exp. Sta. Quart. Bul., 32: 0 Travis, H. F., and P. J. Schaible, 1960. Fundamentals of mink ranching. Michigan State University Circ. Bul. 229. Travis, H. F., R. K. Ringer and P. J. Schaible, 1961. Vitamin K in the nutrition of the ranch mink (in press). warmer, R. G., C. F. Bassett and H. F. Travis, 1957. Cornell Nutrition Conf. for Feed Mfrs., pp. 83. ‘wentz, P. E., and H. R. Hunt, 1951. The measurement of quality in the fur of mink. Mich. Agr. Exp. Sta. Quart. Bul., 34:48. Williams, H. H., L. V. Curtin, J. Abraham, J. K. Loosli and L. A. Maynard, 1954. Estimation of growth requirements for amino acids by assay of the carcass. J. Biol. Chem., 208:277. 115 Wolterink, L. F., H. F. Travis and P. J. Schaible, 1958. A study of fur growth in mink using radioactive tracers. Report to Mink Farmers' Research Foundation, Milwaukee. Wis. Wood, A. J., 1956. Time of food passage in mink. Black Fox Iviag. and Mod. Mink Breeder. 39(9):12. .fpib ..r.‘I". 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