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Sfi. . canto mullllmull\lll‘lllfill 2 5 6W e 71 31293096 LIBRARY Michigan State University This is to certify that the thesis entitled The Effect of Substituting Oyster Shell for Limestone in the Diet of Growing Turkeys presented by Abdolreza Kamyab has been accepted towards fulfillment of the requirements for M.S. degree in Animal Science M1 W “ajor professor/ Date March 21, 1990 04639 MS U is an Affirmative Action/Equal Opportunity Institution PLACE IN RETURN BOX to remove this checkout from your record. To AVOID FINES return on or before date due. DATE DUE DATE DUE DATE DUE ___J __l *l_JL_ JL ——___——_—-__]—[__L———_= MSU Is An Affirmative ActlorVEquel Opportunity Institution THE EFFECT OF SUBSTITUTING OYSTER SHELL FOR LIMESTONE IN THE DIET OF GROWING TURKEYS BY Abdolreza Kamyab A THESIS submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Department of Animal Science 1990 ABSTRACT THE EFFECT OF SUBSTITUTING OYSTER SHELL FOR ' LIMESTONE IN THE DIET OF GROWING TURKEYS BY Abdolreza Kamyab Six hundred seventy-two day-old Nicholas toms were randomly distributed among 16 pens. This experiment was designed to evaluate the effects of oyster shell and limestone as calcium (Ca) sources on turkey leg weakness and body weight. Another objective was to determine if there was a correlation between tibia and toe ash percentage. Records of mortality, feed consumption, and leg abnormalities were maintained throughout the study. Neither Ca source or combinations of calcium source had a statistically significant effect on leg abnormalities, bone ash, body weight at market age or feed conversion between individual treatments. The results indicated that there was a high correlation between tibia and toe ash (r=0.727). This experiment proved that oyster shell is a quality source of Ca for bone development, but is not superior to limestone, which has been reported often with reference to laying hens. To my wife and parents ACKNOWLEDGMENTS I wish to express my deep appreciation to my major advisor, Dr. Cal J. Flegal for his guidance, inspiration, support and concern during my entire graduate program. It was indeed a great privilege to work with such an experienced and knowledgeable man. My sincere gratitude is extended to Drs. Richard Balander, Steven Bursian, and Dwight Schwartz for their helpful suggestion and serving on my supervisory committee. Special thanks go to Mr. A. Napolitano for his help and cooperation during this study. The assistance of Mr. Bill Nobel in the analytical determination is greatly appreciated. I wish to express my most sincere appreciation to my parents who have always been my biggest supporters. Finally to my greatest critic and staunch supporter, my dear wife, Mandana Kamjoo, I acknowledge with fervor the encouragement, patient and love which helped to finish this part of my education. iv TABLE OF CONTENTS I. INTRODUCTION II. REVIEW OF RELEVANT RESEARCH AND THEORY A. Genetical i. chondrodystrophy ii. spondylolisthesis iii. rickets iv. tibial dyschondroplasia (osteochondrosis) v. articular gout B. NUTRITIONAL i. Chondrodystrophy (perosis) a-Minerals, Vitamins and Perosis ii. Rickets iii. Tibial Dyschondroplasia (osteochondrosis) iv. Twisted Leg C. ENVIROMENTAL-MANAGERIAL III. BONE ASH IV. TIBIA ASH VS TOE ASH V. CALCIUM AND PHOSPHORUS REQUIREMENT VI. INFLUENCE OF CALCIUM AND PHOSPHORUS ON GROWTH VII. MATERIALS AND METHODS a. experimental design b. sample collection and handling c. anal sis d. statistical analysis VIII. RESULTS AND DISCUSSION a. feed intake b. mortality 0. feed conversion d. incidence of leg disorders e. body weight f. tibia ash g. toe ash IX. SUMMARY X. LIST OF REFERENCES 10. 11. 12. 13. LIST OF TABLES PAGE Description of some of the leg abnormalities in poultry 1 Ca and P requirements for turkeys as a percentage of diet 28 Ca and P requirements of turkeys as established by the National Research Council 29 Composition of basal diet 35 Calculated analysis of turkey ration used 36 The effect of different calcium sources on feed consumption, numbers of mortality, and numbers of leg deformities in Tom turkeys 42 Feed conversion at 18 weeks of age for Tom turkeys on varying levels of oyster shell and limestone 43 Average body weight at various ages of male turkeys fed varying levels of oyster shell and limestone 44 Average body weight of Tom turkeys at 28 days in kg 45 Average body weight of Tom turkeys at 56 days in kg 46 Average body weight of Tom turkeys at 126 days in kg 47 Percent ash in tibias and toes from male turkeys fed diets containing different sources of calcium 50 Final body weights and total percent tibia ash of Tom turkeys receiving different levels of oyster shell and limestone as Ca sources vi 50 . LIST OF FIGURES FIGURE PAGE 1. Comparison of percent tibia ash and toe ash in Tom turkeys at 4, 6, and 12 weeks of age 49 INTRODUCTION The term leg weakness encompasses a wide range of conditions and is influenced by a number of factors. The following factors have been shown to be associated with leg weakness: 1- Nutritional deficiencies (Sauver, 1984). 2-Genetic factors (Leach and Nesheim, 1965). 3-Poorly defined management factors (Veltmann and -Jensen, 1979). Not all birds affected with deformities are culled or die. Crippled birds are generally not profitable because of depressed growth and removal of deformed limbs when the birds are processed. Considerable research has been conducted towards the control and reduction of leg disorders in poultry. It has been concluded that there is no single solution to the problem. The present article will concentrate on the increasing knowledge of common non-infectious skeletal deformities that have caused significant losses for the poultry industry in the past decade. Many sources of calcium (Ca) such as clam shell, limestone, phosphatic limestone, chalkstone, calcite, mussel shell, egg shell, oyster shell, and quartz have been used to meet poultry requirements. Currently, the most common sources of Ca for laying hens and turkeys are limestone and oyster shell. Even though data indicate that oyster shell is equal to or superior to limestone, the industry predominantly uses limestone in mixed turkey rations for several reasons. The cost of oyster shell is approximately twice that of limestone in some areas of the country and some feed mills are not equipped to add coarse Ca to diets. The objectives of the present study 'were txn l)investigate the effects of limestone and oyster shell in the diets of growing turkeys on the incidence of leg deformities 2)determine if differences exist between tibia and toe ash and 3)to observe the differences in body weights at market age (18 weeks). REVIEW 92 RELEVANT RESEARCH AND THEORY Leg disorders are among the most common deformities in growing,chickens and turkeys ( Fisher, 1972; Julian, 1984; Stevens, 1988). Leg weakness in turkeys was reported to be a significant economic problem for the turkey industry at the symposia (proc. of Cal. conf., 1968; proc. of the symp. on leg weakness in turkeys) in the United State of America. This problem has been reviewed by several. researchers (Norris, 1970; Wise, 1975, 1979; Sauveur, 1975, 1984; Leach, 1979; Riddell, 1981; Randall and. Mills , 1981; Pierson and Hester, 1982). Review restricted to the pathology of all developmental and metabolic disorders of the skeletons of domestic chickens and turkeys was written by Riddell, 1975a; 1975b; Narin and Watson, 1972. Leg abnormalities are most commonly observed between eight and 20 weeks of age (Norris, 1971; Sanger et al., 1974). Turkey hens occasionally develop lameness; however, occurrences predominate in males (Laing, 1976). Leg abnormalities encompasses many different disorders affecting nerves, musculature, and skeletal systems and can be separated into two major categories; infectious and non- infectious disorders (Riddle, 1981). The relative importance of some of the disorders is difficult to establish because detailed data are unavailable (Riddell, 1981) . Undoubtedly, a large portion of the losses from leg weakness are due to skeletal deformities resulting from non-infectious causes. Such skeletal deformities often result in death or culling of more than 1% of the birds in many commercial broiler chicken flocks and more than 4% of the birds in many commercial male turkey flocks (Riddle, 1981). At a symposium in Ames, Iowa, sponsored by the National Turkey Federation (1971) , it was estimated that leg weakness in turkeys caused 4% mortality in flocks of male turkeys. The term leg weakness includes all forms of lameness in addition to any physical abnormality of the leg which may be detrimental to the bird’s performance (Narin and Watson, 1972). The etiology of these deformities remains obscure and poorly understood (Watkins et al., 1988). A number of factors have been cited as causes of osteochondrosis in poultry. Rapid weight gain, nutritional deficiencies (Sauver, 1984) and genetic factors (Leach and Nesheim, 1965; Haye and Simons, 1978; Nestor, 1984; Nestor et al., 1985; 1987) frequently are implicated. Poorly defined management factors, such as litter contamination (Veltmann and Jensen, 1979), lighting (Buckland et al., 1973, 1976; Hester and Kohl, 1989), and exercise (Haye and S imons , 197 8) have also been incriminated . Pierson et al., (1981) tested the possibility (If contribution of sex steroids. They reported that capons demonstrated a significantly higher incidence of leg abnormalities than controls or testosterone—fed birds but did not differ significantly from the Shams . Many primary nutritional deficiencies can cause chondrodystrophy’ or 'twisted. legs. These include several vitamin deficiencies such as choline (Jukes, 1940), biotin (Jukes and Bird, 1942), niacin (Briggs et al., 1943), folic acid (Daniel et al., 1946), and pyridoxine (Gries and Scott, 1972) and trace elements such as manganese (Wilgus et al., 1936), zinc (O’Dell and Savage, 1957) and nickel (Sunderman et al., 1972). Copper deficiency also results in a cartilage defect similar to tibial dyschondroplasia (Carlton and Henderson, 1964) while rickets can be related to calcium, vitamin D3 or most frequently phosphorus deficiency. Follis (1974) added boron to this list. However, these simple dietary deficiencies are now extremely rare under field conditions (Wise, 1979) and leg weakness is still often observed although the diet contains all the known nutrients necessary for normal growth. Sauveur (1984) concluded that certain hypotheses can be presented regarding leg abnormalities in poultry. They are: 1-No association exists between any nutritional factor and modern leg weakness. Z-Several dietary factors interact to produce leg weakness. 3-Some feed ingredients contain unknown (anti-nutritional) factors. A) GENETIC In response to the demands of consumers and producers, breeders of meat-type poultry have concentrated their genetic improvement efforts on selection for heavier body weights and wider breast conformation at a given market weight. The effectiveness of their efforts on the growth rate of turkeys has been well documented in a review by Arthur and .Abplanalp (1975), and in recent reports by Nestor (1984) and by Delabrosse et al. (1986). Havenstein et a1. (1988) reported that only one study (Delabrosse et al., 1986) is available at this time on the: genetic ' relationship between body weight, various body parts, and fat deposition in turkeys. Although ‘the genetic influence on leg ‘weakness :hn turkeys has not been studied to the same extent as in chickens, many of the abnormal leg conditions that are found in broiler chickens also occur in turkeys (Nairn and Watson, 1972). Various leg abnormalities in broiler chickens have been shown to be highly heritable (Sheridan et al., 1974, 1978; Burton et al., 1981; Mercer and Hill, 1984), to exhibit strain differences (Haye and Simons, 1978; Veltmann and Jensen, 1981; Nestor, 1984; Nestor et al., 1985, 1987), to respond rapidly to selection for a decreased incidence of leg abnormalities (Serfontein and Payne, 1934; Leach and Nesheim, 1965, 1972; Riddell, 1976), and to be under the influence of major genes (Somes, 1969; Sheridan et al., 1974). Selection for increased 16-week body weight increased the number of leg problems in turkeys (Nestor, 1984), and selection for increased shank width reduced the number of leg abnormalities and improved walking ability in turkeys (Nestor et al., 1985, 1987). Unfortunately, many research workers and commercial producers feel that the use of selective breeding has resulted in a concomitant increase in the incidence of leg abnormalities (Wise and. Jennings, 1972; Poulos et afil., 1978). It has been suggested that the broad breast of the turkey tom, because of its excessive weight, causes undue pressure on the leg muscles and bones making males more susceptible to leg weakness than females (Steinke, 1971; Laing, 1976). Such stress might be reduced if growth plates closed at an earlier age, when body weights were less (Klingensmith et al., 1986). However, evidence against this includes the following: 1) turkeys whose feed was restricted so as to significantly reduce rate. of gain showed. the same incidence of leg weakness as full-fed controls (Adams and Stadelman, 1978); 2) within a medium weight strain of turkeys, the lightest birds were just as susceptible to leg weakness as the heaviest birds (Buffington et al., 1975); 3) a lighter strain of turkeys did not differ in leg weakness incidence (36.1%) from a heavier strain (27.2%) (Adams and Stadelman, 1978). However, Steinke (1971) reported that a heavier strain of male turkeys had a greater incidence of abnormal cartilage lesions in the tibia than a lighter strain and that progeny resulting from a cross of the two strains were intermediate in body weight and abnormal cartilage formation. Male turkeys whose feed was restricted by 20% between five and 10 weeks of age showed a reduction in body weight and incidence and severity of abnormal cartilage formation of the tibia. Nestor et a1. (1985) hypothesized that direct selection for increased amount of breast muscle as well as for greater total body weight had caused total body weight and breast muscle to increase at a faster rate than the muscles and bones of the legs, and that this disproportionate change had caused an inherent weakness in the bird, which resulted in leg problems (Table 1). Table 1. Description of some of the leg abnormalities in poultry Leg abnormality Synonyms Symptoms Long Bone Eustortion Osteodystrophy, -Twisted or Crooked legs, bending of Knock-kneed (valgus, tibia and and Twisted legs tarsometatar- sus -Displacement of the gastr- ocnemius, Table 1 (cont’d) tendon avulsion Rickets Field Rickets -Ends of long bones becomes enlarged -Soft andrubbery bones -Failure of bone mineralization Rotated Tibia Spraddle Leg -Lateral rotation of tibia approximately 40 -Neither tibia nor metatarsus is bent -Found in young birds Spondylolisthesis Kinky Back -Hock sitting posture -Deformed sixth thoracic verteb- ra -Spinal cord damage Tibia Dyschondroplasia Osteochondrosis -Abnormal mass of cartilage in the proximal tibia -Variable lameness Adapted from Feedstuffs, July 20, 1987; reported by Sarah Muirhead i. Chondrodystrophy Early studies by Asmundson (1942) and Lamoreux (1942) demonstrated that chondrodystrophy, a form of leg weakness characterized by short, thick and often misshapen leg bones, was clearly a heritable trait in broiler chickens. 10 The occurrence of a similar semi-lethal chondrodystrophic condition in the turkey was confirmed by Asmundson (1944) who attributed its heritability to an autosomal recessive gene. Somes (1969) also reported chondrodystrophy due to an _ autosomal recessive gene. Chicks were normal at hatching, but an enlargement of the hock joint and bending of the tibia and metatarsus outwards occurred between three and five weeks of age. Leach and Buss (1977), in efforts to characterize the chemical and histological changes associated with inherited chondrodystrophy, found that the cartilage of affected turkey embryos contained less than 50% of the galactosamine-mucopolysaccharides jpresent :h1 normal cartilage and that it.luni considerably less extracellular matrix. Breed and strain differences in manganese requirements and susceptibility to perosis were reported by Gallup and Norris (1939). Narin and Watson (1972) suggested that the use of the term perosis be discontinued. 511 avian pathology; 'Wise (1975) proposed. the use of the term chondrodystrophy in birds to replace the term perosis, because the latter term meant different things to different people. To some, it was descriptive of a slipped gastrocnemius tendon, to others it implied a deficiency of manganese or choline, while a third group applied the term less specifically’ to a ‘wide range of leg deformities. 11 ii. Spondylolisthesis .A possible genetic explanation for spondylolisthesis was provided by Osbaldiston and Wise (1967) who felt that weaknesses in the thoracic vertebrace may have been either specifically selected for or resulted from undue mechanical stress imposed by major genetically-induced changes in body conformation, i.e. redistribution of body mass. The supposition of genetic involvement was further supported by the work of Riddell (1973) who developed a line of broilers with a high incidence of spondylolisthesis by selective breeding. Similarly, Khan et al. (1977) maintained an incidence of spondylopathy between 58% and 66% through four successive generations of broiler progeny. Most birds with spondylolisthesis ,commonly known as "kinky back", assume a hock-sitting posture with legs extended forward. As the birds attempt to move with the aid of their wings, they tend to move backward. Birds are alert and eat and drink if given access to feed and water (Riddell and Howell, 1972). It has been claimed that twisted leg and kinky back have a common aetiology (Osbaldiston and Wise 1967), but it is hard to reconcile this theory with the: unilateral characteristic of twisted leg (Nairn and Watson 1972). This condition has not been described in the turkey (Flegal, 1989). 12 iii. Rickets' From a comparative view point , rickets in domestic animals is generally associated with a nutritional deficiency (Jubb and Kennedy, 1970), although an inherited form of rickets has been described in pigs (Plonait, 1969). Austic et al. (1977) conducted a study involving a sex linked dwarf strain of chickens. Results indicated that when optimal dietary levels of vitamin D3, phosphorous and calcium were provided, the maximal level of bone mineralization was significantly lower for dwarfs when compared. to controls, whereas low levels of all three affected bone mineralization in both groups. It was consequently suggested that the apparent susceptibility of the dwarf strain to rickets was the result of genetic alterations in the rate of deposition of bone minerals. Kramer and Waibel (1978) reported that when turkey breeder hens received 2400 IU vitamin 03/ kg in their diet, none of their progeny raised on a vitamin D3-deficient diet had leg problems by two weeks of age. However, when hens received 0 or 300 IU/ kg of vitamin D3 in their diet, a 40 to 60% occurrence of rickets resulted in their progeny. iv. Tibial Dyschondroplasia (Osteochondrosis) Tibial dyschondroplasia (T.D.) is a common bone deformation in growing broiler chickens and turkeys through out the world (Walser et al., 1982). The lesion is 13 characterized by an abnormal mass of cartilage in the proximal end of the tibia (Lowther et al., 1974; Poulos et al., 1978). The condition was named by Siller (1970), and first described in broiler chickens by Leach and Nesheim (1965), in turkeys by McCapes (1967) and in ducks by Wise and Jennings (1972). White Leghorns are not afflicted with this leg abnormality (Reilland et al., 1978). In an early report, McCapes (1967) called the condition osteochondrody- strophy, while Reiland et al. (1977) proposed that T.D. is part of a generalized disease that was named osteochondrosis by Olsson (1978). Clinical signs described in most of the reports included a reluctance of birds to move, abnormal posture, a stilted gait, and bilateral swelling of the femoral-tibial joints, often associated with anterior lateral bowing of the tibia. Leach and Neshein (1965) confirmed the heritable nature of this disease by mating selected sires and dam to develop two strains of broilers: one demonstrating a high incidence of T.D. (41%) and another showing a low incidence (16%). Similar work was performed by Riddell (1976) who, by using radiography to select normal and affected birds for breeding, was able to develop broiler strains exhibiting either a 50.9% or 0.0% incidence. 14 v. Articular Gout Picken et al. (1921) reviewed early reports on articular and visceral gout in poultry. Siller' (1959) considered that visceral and articular gout were distinct entities and commented that this was not emphasized enough. Articular gout has been found to occur in both fowls (Cole et al., 1969) and turkeys (Schlotthauer and Bollman, 1934; Snoeyenbos et al., 1962). It is known to be associated with excessive plasma uric acid levels and subsequent deposition of monosodium urate in joint and tendon tissue (Austic and Cole, 1972). Evidence of genetic influence was provided by Cole et al. (1969) who were able to establish a line of fowls having' elevated plasma uric acid levels. It. was later suggested (Austic and Cole, 1972) that genetic predisposition to impaired renal uric acid clearance was the reason for higher plasma uric acid levels and au1 increased susceptibility to articular gout. B) NUTRITIONAL It is well established that many primary nutritional deficiencies can cause chondrodystrophy, rickets, T.D. and twisted legs. These include several vitamin and mineral deficiencies. Nutritional disease may result from a deficient or imbalanced intake of“ nutrients, and as result of non- 15 specific or specific changes in tissues may be encountered (Riddell, 1975a). Stevens and Salmon (1988) reported that feeding higher than recommended levels of dietary protein may' predispose turkeys to early leg' problems, cause a reduction in bone ash and an increase in the overall incidence of leg deformities at market age. Summers et al. (1984) proposed a protein-vitamin D3 interaction which increased the requirement for calcium of birds on high protein diets. This was aggravated by vitamin D3 deficiencies. Stevens et al. (1982) suggested that levels of dietary fat and vitamins A and D3 in the diet may be predisposing factors to rickets in young poults. During the past several decades, the role of nutrition in the production of avian leg deformities has been a topic of intense study. It is appropriate that these findings be presented in the following text. i. Chondrodystrophy (perosis) Chondrodystrophy, or perosis as it is more commonly known, is also refered to as slipped tendon. It is characterized by enlargement of the hooks, by twisting or bending of the distal end of the tibia and the proximal end of the metatarsals and by frequent slipping of the Achilles tendon from its position in the intercondyloid fossa at the rear of the hock (Norris and Scott, 1948). A higher incidence of a perosis-like condition has 16 been described in broilers reared in cages when compared with broilers reared on the floor (Reece et al., 1971; Seth and Clandinin, 1973). Rondenhoff and Dammrich (1971) described no skeletal deformities in broiler chickens kept out-of—doors, while 6% of the birds kept inside had skeletal deformities. a Minerals, Vitamins and Perosis Mineral involvement. in. perosis 'was first suspected when it was reported by Wilgus et al. (1936, 1937) that the condition in chickens could be due to a deficiency of manganese. However, it has also been reported to be due to other nutritional deficiencies (Leach, 1968). Caskey et al. (1939) indicated that manganese deficiency produced a reduced bone ash and chondrodystrophy characterized by shortening of bones. Young et al. (1958) observed that a diet deficient in zinc but containing adequate levels of all other known nutrients produced symptomatic perosis. Evans et al. (1942) described perosis in turkeys due to either a manganese deficiency or a choline deficiency. Poults had enlarged hocks by the end of the first week of life. Later, twisting of the metatarsus and slippage of the tendon at. the tibiometatarsal joint occurred. Symptoms were most severe at four weeks of age. Both varus and valgus deformations were observed. 17 Perosis due to a deficiency of choline has been described in turkeys (Jukes, 1940a, 1940b) and chickens (Hogan et al., 1941). In both species, the leg bones were shortened and thickened and the hock joints were distorted. Wise et al. (1973) described histopathological changes in the proximal growth cartilages of the humerus, tibiotarsus and tarsometatarsus of choline deficient poults. Richarson et al. (1942) and Anderson and Warnick (1970) described perosis in chicks fed a diet deficient in biotin. Hocks became enlarged and turned inwards by 28 days. In severe cases, the Achilles tendon slipped. Dobson (1967, 1970) described the lesions produced by a biotin deficiency in poults at three weeks of age as a bowing of the legs associated with dermatitis. Patrick et al. (1942) found that the incorporation of biotin into the diet of turkeys could relieve both the symptoms of perosis and foot pad dermatitis. Jensen and Martinson (1969) reported that a biotin deficiency can be readily developed in turkey poults without resorting to a diet containing avidin as is necessary with mammalian species. Perosis can occur without dermatitis in both biotin deficient chicks and poults (Patrick et al., 1942). Jensen and Martinson (1969) presented evidence that there was more leg weakness in turkeys at 18, 20 and 24 weeks of age when low biotin rations were fed during the first few weeks of life. Gries and Scott (1972) described a failure to grow, 18 ataxia and death in chicks fed low levels of pyridoxine (vitamin B6). Severe perosis was developed by two weeks of age in these birds. Clinical perosis was demonstrated in chicks fed a diet containing adequate levels of choline, biotin and manganese but only low levels of folic acid (Daniel et al., 1946). ii. Rickets Mellanby of England was first to formally recognize rickets as a nutritional disease. The name derived from the old English word "wrikken" meaning to bend or twist (Scott et al., 1982). Rickets is a disease of the young, characterized by a failure of mineralization of osteoid and epiphyseal cartilage (Jubb and Kennedy, 1970). Lameness occurs when the ends of the long bones become enlarged and exceedingly flexible due to a lack of calcification (Wise, 1975). It was generally considered to be the result of a deficiency or imbalance of vitamin D3, calcium, or phosphorus (Riddell, 1981). Brenes (1971) fed poults diets varying in calcium, phosphorus, and vitamin D3. Rickets was first observed at five days in poults fed low phosphorus diets, at six days with high phosphorus diets, at seven days with low calcium diets, at 10 and 11 days in poults fed no or a very low level of vitamin D3, respectively. He also reported that birds fed these diets to 24 days of age and then fed normal 19 diets recovered at different rates. All turkeys appeared normal at six weeks of age except that birds previously fed low or high phosphorus diets showed a high incidence of leg disorders from 10 to 20 weeks of age. Scott et al. (1932) reported that turkey poults receiving a diet deficient only in vitamin D3 developed symptomatic rickets in 18 to 20 days. A lack of remedial supplementary vitamin D3 resulted in 100% mortality by 30 days. In a comparative study of the effects of a deficiency of calcium, phosphorus or vitamin D3 on bones of chicks, Groth and Frey (1966) indicated that the histological .lesions in vitamin D3 deficiency and calcium deficiency were similar. In an outbreak. of rickets in broiler chickens in Germany (Kohler et al., 1978), circumstantial evidence implicated contamination of the feed with metabolites of Fusarium moniliforme Sheldon. It was suggested that these metabolites may affect the structure of vitamin D3. Aflatoxin may also interfere with vitamin D3. It will also reduce the blood calcium level of chickens but will not produce rickets in chickens when adequate levels of vitamin D3 are fed (Hamilton et al., 1974). 20 iii. Tibial Dyschondroplasia (Osteochondrosis) Tibial dyschondroplasia (T.D.) is a common abnormality of broilers and heavy turkeys, particularly males (Walser, 1987). The condition frequently is presented in lame birds, but it can also be found in birds with a normal stance and gait (Walser et al., 1982). T.D. has been studied less extensively in turkeys and ducks, but the lesions appear to be identical to those in chickens (Riddell, 1981). It is also agreed that T.D. in commercial poultry is identical to a condition characterized by abnormal cartilage in the proximal tibia described by Leach and Nesheim (1965) 11! experimental chickens fed a purified ration. Dietary levels of calcium (Ca), phosphorous (P) (Edwards and Veltmann, 1983), and chloride (Cl), (Leach and Nesheim, 1972) have been shown to influence the incidence of T.D. in broiler chickens. The addition of zeolite to broiler diets low in Ca caused a reduction in the incidence and score of T.D. (Ballard and Edwards, 1988; Edwards, 1988). Dietary zeolite supplementation has also been reported (Roland et al., 1985; Miles et al., 1987) to cause beneficial effects on egg shell quality (increased specific gravity) when added to diets of laying hens. If" the beneficial effects of zeolite on egg shell quality are associated. with improved. utilization of calcium, it; is 21 possible that feeding zeolite to broiler chicks may influence the development of T.D. as the development of the disease is influenced by dietary calcium (Edwards anui Veltmann, 1981). In most of the experiments reported, zeolite has caused a significant increase in bone ash and in one experiment it increased the retention of calcium (Edwards, 1988). Edwards (1983) showed that reducing total phosphorus from 0.70% in a corn-soybean meal diet to 0.45%, when the calcium level was maintained constant at 1.0%, caused a reduction in 3-week body weight of broiler chicken from 360g to 97g and a reduction in bone ash from 38.5% to 26.9%. Elliot and Edwards (1989) reported that increasing dietary boron in broiler feed had no effect on bone ash and T.D. incidence but did linearly increase the severity of T.D. In addition, there was a significant calcium-boron- vitamin D3 interaction on the severity of T.D. iv. Twisted Leg Twisted leg is a condition commonly found in young meat type fowl in which there is laternal twisting and bending of the distal tibiotarsus and bending of 'the proximal tarsometatarsus (Nairn and Watson, 1972). Unlike perosis, the gastrocnemius tendon does not usually slip (Osbaldiston and Wise, 1967). 22 Supplementing a diet with pyridoxine reduced the incidence of twisted legs (Cope et al., 1979; Beirne and Jensen, 1981). As these authors gave no explanation for the beneficial effect of pyridoxine, it is suggested (Sauveur, 1984) that this may have been due to an interaction with zinc metabolism or more precisely with the formation of picolinic acid involved in intestinal zinc absorption. C) ENVIROMENTAL-MANAGERIAL Several researchers and commercial producers have suggested that environmental and managerial factors may influence the development of leg weakness in poultry (Anonymous, 1979) . There is not enough published work available on which to evaluate this hypothesis. Hester et al. (1983) reported that the incidence of leg deformities and length of the tarsometatarsal were significantly decreased in the high intensity step-up (201x) lighting. Hester et al. (1986) in another study, compared a high vs. low intensity step-up lighting program. The high intensity step-up lighting program not only caused male turkeys to mature sexually at an earlier age, but also reduced the incidence of leg abnormalities by 50% when compared to the incidence of abnormalities in turkeys on the low intensity step-up lighting. Buckland et al. (1973, 1976) found that turkeys grown in continuous light had 23 significantly more leg abnormalities than those subjected to intermittent lighting schedules. Poor litter conditions (Hester et al., 1987) and litter contamination (Veltmann and Jensen, 1979) have been suggested as possible causes of leg deformities. Foot-pad dermatitis in broilers and turkeys has been associated with wet, crusty litter conditions (Abbott et al., 1969; Martland, 1984). Steinke (1971) reported an 80% incidence of shaky walk-type leg abnormalities in turkeys raised on artificially dampened litter compared with a 5% incidence for control turkeys. There was no difference in the incidence of leg deformities in male turkeys raised on pine shavings or whole rice hulls at depths of 5 or 10 cm (Hester et al., 1985). Rowland et al. (1971) and Siegel et al. (1973) indicated that high ambient temperatures further decreaced bone strength associated with confinement of broilers to cages. Likewise, high environmental temperature has been shown to increase the occurrence of leg deformities in caged broilers (Reece et al., 1971). Bone Ash Percent bone ash has been used as a parameter for measuring the importance of the Ca:P ratio (Choi et al., 1977), to determine dietary adequacy i.e., vitamin 113 levels (Yang et al., 1973), and also as a criterion for 24 bone mineralization (Brenes et al., 1971) and bone strength (Yang et al., 1973). Choi et al. (1977) fed day-old turkey poults four levels of available phosphorus and established ratios with Ca. Their results showed that the Ca:P ratio of 2:1 gave the best overall performance and 0.45% available P gave the most favorable weight and feed efficiency results, while 0.74% available P resulted in the highest bone ash results. Yang et al. (1973) have recommended the use of bone ash as a way of determining bioavailability of different sources of vitamin D3, because bone ash gave the best precision in short term studies. They suggested that growth parameter be used for long term experiments. They also obtained a positive correlation between vitamin D3 levels, femur ash, length and breaking strength of femur in turkeys. Warnick and Anderson (1976) have shown that when turkey hens reared on the floor and in cages were fed varying levels of Ca and P, bone ash was higher in the birds receiving the high P supplemented diet. Bone ash was also 22% higher in floor-reared than in cage-reared turkeys. Incidence of leg problems, conversely, was less in birds fed higher P diets and in those reared on the floor compared to those reared in the cage. 25 The usual procedure for studying calcification in growing chicks has involved a determination of the percent ash in‘the tibia of the chick. Baird and MacMilan (1942) were among the first scientists to suggest the use of toe ash instead of tibia ash in chicks. The toe ash procedure in chicken has the advantage of being less expensive, and much quicker and results are equivalent to the results obtained with the tibia ash procedure. Toe ash percentages have been used as a way of determining calcium (Simco and Stephenson, 1961), phosphorus (Fritz and Roberts, 1968; Potter, 1988), and vitamin D3 (Baird and MacMilan; 1942) availability. Potter (1988) used a medium-sized strain of male and female turkey poults to determine the bioavailability of phosphorus from eight different sources using body weight and toe ash measurements as parameters. Each P source was added to the basal diet composed of 52% dehulled soybean meal and 41% ground yellow corn to supply 0.09, 0.18 or 0.27% P to form 24 diets with a constant Ca content. Each diet was fed to 16 turkeys (eight of each sex/pen) from one to four weeks of age in the first experiment and to 32 poults (16 of each sex/pen) from 0 to four weeks of age in a second experiment. The percentage ash of the middle toe and average body weight at four weeks of age provided similar relative P availability values from the various 26 sources . Manning and McGinnis (1976) fed three levels (0.5, 0.6, and 0.7%) of total P to 12-week old tom turkeys and measured toe ash and weight gain. The lower level of total P resulted in the least percentage toe ash when compared to the other two P levels, although this was not significantly different. Yoshida and Hoshii (1983) reported a positive correlation between tibia and toe ash values of 18 day-old meat and egg type chickens. Likewise, Fritz and Roberts (1968) found a positive relationship between tibia ash and toe ash of chicks. 27 CALCIUM AND PHOSPHORUS REQUIREMENT Calcium and phosphorus are considered together because they are closely associated in metabolism, particularly in the formation of bone (Scott et al., 1982). Wilgus (1931) was first to establish the quantitative limits for Ca and P for normal bone formation in chicks. He showed not only that the diet must contain minimum levels of the two elements, but also an optimum ratio of Ca:P. He also reported that the minimum available P requirement is roughly 0.5%. The Ca:P ratios needed for normal growth in chicks varies between 1.0:1.0 and 2.2:l.0. The 2.5:l.0 ratio was borderline, while a ratio of 3.3:1.0 appeared to be disastrous, producing rickets and other leg abnormalities. The Ca requirement in the diet is met by combinations of ingredients including fish meal, bone meal and dicalcium phosphate. Presently, oystershell and limestone, which contain 38% or 39% Ca, are most frequently added to the diet as sources of supplemental Ca. The present requirements established in 1984 are 1.2% Ca and 0.6% P for turkey poults (0-4 weeks of age), 1.0% Ca and 0.5% P (4-8 weeks), 0.85% and 0.42% P (8-11 weeks), 0.75%Ca and 0.38% P (11-14 weeks), 0.65% Ca and 0.32% P (14-17 weeks), and 0.55% Ca and 0.28% P from 17 to 20 weeks of age (Table 2). 28 Table 2. Ca and P requirements for Turkeys* as a Percentage of diet Male: 0-4 4-8 8-12 12-16 16-20 20-24 Female: 0-4 4-8 8-11 11-14 14-17 17-20 ____________________ %_-_-__-__-___--_____-_ Calcium 1.20 1.00 0.85 0.75 0.65 0.55 P available 0.60 0.50 0.42 0.38 0.32 0.28 *: Based On National Research Council (1984) Potter (1975) made the following observations relative to Ca research as it relates to the nutrition of turkeys: 1-Calcium is required in greatest quantity when compared to the other minerals in the diet. 2-It is the major mineral component of bone. 3-Ca cost is the lowest of all major nutrients in the diet. 4-The Ca requirement cannot be established without first stating the P and vitamin D3 requirements. 5-The Ca level in the diet of young turkeys (0-8 weeks) is about 1.2% and decreases with age until the requirement is about 0.6% (20-24 weeks of age). 6-By increasing Ca content in the diet, as stated above, feed efficiency and bone calcification will decrease. 29 Waibel (1977) concluded the following, in reviewing P research on turkeys. 1-The Ca and P requirements of turkeys decreases with age. 2-The Ca:P ratio is important. 3-One of the best sources of P is monocalcium phosphate. 4-The estimated Ca and P'requirements have decreased over the years (Table 3) from 2.0 and 1.0% respectively to 0.8% Ca and 0.8% P. Table 3. Ca and P Requirements of Turkeys as Established by The National Research Council 1944 1950 1954 1960 1966 1971 1977 ------------------ Requirements(%)----------------- Ca ' 0-8 Wk 1.6 2.0 2.0 2.0 1.2 1.2 1.2 8-16 Wk _ 2.0 2.0 1.7 1.2 0.8 0.8 P 0-8 Wk 1.0 1.0 1.0 1.0 0.8 0.8 0.8 8-16 Wk 1.0 1.0 0.85 0.8 0.7 0.7 The estimated Ca and P requirements have decreased over the years from 2.0% and 1.0%, respectively, to 0.8% Ca and 0.8% P. 30 Most of the reports on Ca and P in turkeys have concentrated on the availability of various sources of Ca, P and their influences on bone mineralization. Andrews et al. ‘(1972) conducted three experiments to study the utilization of P from plant material by turkey poults. The best performance in all the experiments was obtained from a degerminated corn meal basal diet which contained 0.7% Ca and 0.59% total P or 0.32% available P. They also concluded that a large portion of total organic P was available for utilization by turkey poults. Influence of Calcium and Phosphorous on Growth Calcium and phosphorous are essential for the formation and maintenance of the skeletal structure. Over 90% of the body Ca is present in the bone. It is estimated that one-third of the weight of fat free dried bone is due to Ca (Scott et al., 1982). The Ca:P ratio would seem to be of some importance, since an excess of one results in depletion of the other. An optimum Ca:P ratio in the diet apparently lessens the requirement for vitamin D3, but with a vitamin D3 deficiency, no Ca:P ratio will produce good bone (Branion, 1938). The effect of limestone particle size on Ca availability has been investigated by Hillman et al. (1976) . They reported that finely ground limestone increased the availability of Ca to poults, improved the feed efficiency, and produced higher weight gains at a low dietary Ca level. Hurwitz et al. (1978) studied the influence of Ca intake on P absorption. They fed five levels of Ca (0.80 to 2.13%) and three levels of P (0.65 to 1.30%) in a cross- classified arrangement. At each Ca level, P absorption and retention increased with increasing dietary P. These data suggested that there was no saturation of the P absorption process. Phosphorus retention, however, remained about the same after a dietary level of 0.80% Ca. As the Ca level increased, P intake was decreased without affecting the P 32 absorption ranking within each Ca level. Also, as P absorption increased, urinary P increased. The results presented tended to show that P absorption was positively related to P intake irrespective of the dietary Ca level. However, an increase in the dietary Ca will reduce I’ absorption by reducing relative P intake. The major factor moderating blood P levels acts primarily on the kidney rather than on the intestine. Keshavarz (1986) conducted three experiments to evaluate different dietary levels of Ca and P on production of laying hens. In the first experiment, the birds were 56 weeks old at the beginning of the experiment. Birds were fed the experimental diets, with Ca levels of 3.5, 4.5, and 5.5% and available P at levels of 0.24, 0.44, and 0.64%, for 16 weeks. Egg production, egg weight, egg shell quality, feed consumption, and tibia ash were not significantly affected by different dietary levels of Ca. Dietary levels of P did not have a significant effect on the aforementioned parameters, except that feed consumption was significantly lower with the lowest level of dietary P (0.24%). The retention of Ca was increased, but that of P decreased with increasing levels of Ca. Keshavarz (1986) also reported that dietary levels of P did not significantly affect the retention of Ca or P. In a second experiment Keshavarz (1986) fed four levels of Ca (3.5, 4.5, 5.5, and 6.5%) to 42-week old laying hens for 20 33 weeks. Production parameters were not significantly affected by different dietary levels of Ca. In the third experiment, Keshavarz (1986) used 3.5, 5.0, and 6.5% Ca. Birds were 80 weeks old and were fed the experimental diets for 16 weeks. In this experiment egg production and egg weight were significantly lower with 6.5 % Ca than with lower levels of Ca. Keshavarz suggested. that: 1) high dietary levels of Ca may significantly affect the performance of old hens, 2) short duration of high Ca feeding does not seem to significantly affect the performance of young hens and 3) Ca:P ratio is not as crucial in laying hens as in growing chicks. Frost and Roland (1989) used 21-week old DeKalb XL ‘ pullets to determine the effect of the dietary levels of Ca and P on bone formation and production performance. Experimental diets containing three levels of Ca (2.75, 3.75, and 4.25%) and three levels of total P (0.50, 0.60, and 0.70%) were fed for a period of six weeks. Results of this study showed that feed consumption increased as dietary Ca increased and decreased as dietary P decreased. Reducing dietary P had no influence on bone weight or ash, but bone ash and bone weight increased significantly with increasing dietary Ca. Dietary Ca and P did not affect egg production. MATERIALS AND METHODS A.Experimental Design A total of 672 day-old Nicholas toms were randomly distributed among 16 identical floor pens measuring 4.6 m x 3.0 m, resulting in 42 birds per pen. Extra poults served as replacements for birds that died during the first three days. All the birds were injected with an antibiotic at the commercial hatchery where they were purchased. Each pen was equipped with one gas brooder, brooder guard, a vacuum fount-type waterer, a flat tray for feed and a hanging bell-type waterer. Each pen floor was bedded with wood shavings as litter. The litter was covered with cheesecloth for the first three days of the experiments to prevent eating of the wood chips. Then it was removed for the remainder of the experiment. Two cylindrical feeders replaced the feed tray after the first week and the fount- type waterer was removed at the same time. Groups of turkeys were randomly assigned to test diets for an 18-week experimental period with four replicates assigned to each of four test diets. The diets were as follows: Diet 1. Basal control with all added ca as ground limestone Diet 2. Basal diet with 1/3 Ca as oyster shells, 2/3 as ground limestone 34 35 Diet 3. Basal diet with 2/3 Ca as oyster shells, 1/3 as ground limestone Diet 4. Basal diet with all added Ca as oyster shells All the diets were formulated to contain a constant apparent metabolizable energy, crude protein, and Ca:P ratio. The basal diets (starter, grower, and finisher) used in this experiment are shown in Tables 4 and 5. Table 4. Composition of Basal Diet Starter Grower 1 Grower 2 Finisher 1 Finisherz Age (day) 0-21 22-49 50-84 85-112 113-126 Feed Description ---------------- Pounds/Ton --------------- Corn, yellow 820 831 1047 1213 1427 Soybean meal 995 950 754 580 360 (48%) Meat and bone 50 50 50 50 50 meal (50%) Fat 49 86 80 89 92 Dicalcium phos. 36 36 27 29 31 Limestone 26 26 22 21 21 Salt 8 8 8 8 8 Vitamins/trace 12 10 , 10 10 10 minerals Methionine, DL 4 1 1 _ 1 Antioxidant + + + + + Coccidiostat _ 2 1 _ _ (Coban) Total 2000 2000 2000 2000 2000 A starter, two grower, and two finisher rations were fed beginning at 0, 3, 7, 12, and 16 weeks of age (Table 4). Rations were formulated to meet or exceed all known 36 turkey nutrient requirements (National Research Council, 1984). Table 5 shows the calculated analysis of diets used in this experiment, (based on National Research Council, Nutrition Requirement for Poultry, 1984). However, the basal diet in this experiment did not contain added Ca in the form of oyster shell, but rether as ground limestone, with a Ca:P ratio of 2:1. The Ca:P ratio for all the experimental diets was the same as the basal diet, but the levels of limestone and oyster shell were different, as explained earlier. Table 5. Calculated Analysis of Turkey Ration Used Starter Grower Grower Finisher Finisher w 0-3 3-7 7-12 12-16 16-18 ME, Cal/Kg 2866 2976 3086 3197 3307 ME,Cal/1b 1300 1350 1400 1450 1500 Protein, crude % 28.5 27.5 23.6 20.0 15.7 Fat % 4.4 6.2 6.3 7.0 7.4 Fiber % 2.7 2.6 2.6 2.6 2.5 Calcium % 1.22 1.23 1.03 1.03 1.03 Avail. P % 0.61 0.61 0.51 0.51 0.51 Total P % 0.86 0.85 0.74 0.72 0.70 Feed and water were provided ad libitum throughout the entire study. Gas brooders were used during the first and second weeks to maintain floor temperature at approximately 37 95 and 90° F. Brooder guards were removed after the first week. The use of gas brooders was discontinued at the end of the third week. Brooder guards were used to keep poults close to the source of feed and water. Ambient temperature was maintained at 90 to 95° F from 0 to 2 weeks~of age. Subsequent decreases of 5° F per week occurred when the turkeys were 3 'weeks of age. Thereafter, temperature fluctuated depending (n1 outside environmental conditions, but attempts were made to maintain a minimum temperature of approximately 60 to 65° F for the remainder of the experiment. All poults received a continuous photoperiod during the first three days. Beginning of the forth day, light hours were reduced by 1 hr each day until 15 hr of light were achieved at 12 days of age. This 15 hr photoperiod was maintained from 12 days of age until marketing at 126 days of age. Efforts were made to keep environmental conditions such as temperature, ventilation rates, and lighting similar“ in each. pen. Records of mortalityy feed consumption, and leg abnormalities were maintained through the study. Wet and caked litter was removed, and new litter was added, resulting in litter management considered to be ideal. Each pen initially received 22 lg; of litter which resulted in a average depth of 7-8 cm. 38 B.Sample Collection and Handling Body weights were obtained at 1, 28, 56, and 126 days. At 4 and 8 weeks of age, each tom was placed on the scale within ‘a cone box that had an opening on one side. Birds within each pen were herded into a crate with the use of a catching fence. Birds were returned to the pen immediately after recording the weight. During the weighing process at 18 weeks of age, each bird was placed on the scale. Feed was weighed back on the day that the feed was changed and feed. efficiencies. calculated. Feed. efficiency' data.‘were calculated on a per pen basis. At 2, 4, 6, and 12 weeks of age, three turkeys from each pen (words 12 birds per replicate), were selected at random, leg banded, and then processed. Neither feed nor water was removed from the birds prior to slaughtering. The right leg from the proximal end of the tibia was cut with pruning scissors and frozen for latter removal of the tibia and middle toe. Lachat (1937) reported that the process of freezing bone did not affect the subsequent estimation of ash. Turkeys that were sacrificed were selected regardless of their walking ability. The right tibia was removed from each bird sacrificed, and cleaned of soft tissue by placing the tibia in boiling water for about five minutes (after thawing). The remaining tissue was mechanically removed. The bones were air dried for 24 hr, crushed (to facilitate the extraction of lipid material), tagged and wrapped in 39 cheesecloth. The fat was extracted from the tibias with petroleum ether for 24 hr. The bones were then and susequently placed in absolute ethanol for 24 hours. After these extractions, the bone was considered dry and fat free. C.Ana1ysis The bone ash procedure was identical to the technique used by Reynnells (1979). All the tibias were individually weighed in a tared crucible. The bones were placed in a cold furnace and the temperature was allowed to rise to 650° C. Bones were then ashed at about 650° C for approximately 20 hr in a muffle furnace. The percentage of bone ash was determined by using the data of ashed bone and dry fat-free bone. The middle toes (first and. second fragments) were also cut off, boiled, air dried, extracted, air dried, weighed and ashed using the same procedure as used for the tibia. The only exception was boiling time. The toes from birds of all ages were boiled for only two to three minutes. Leg abnormalities were described under the categories of 51 ipped tendon , swollen hock joint , bowed tarsometatarsus (shanks), knock-kneed at the tibia- tarsometatarsal joint, rotation of the tibia, rotation of the tarsometatarsus, or the unability to walk. 40 Statistical Analysis The data were subjected to an analysis of variance or regression analysis and least significant difference where applicable. Significance are based on a p<0.05. Analyses were performed using the General Linear Models Procedure on the Statistical Analysis System (SAS, 1987). Results and Discussion Feed Intake- Feed intake in this experiment is shown in Table 6. The diet fed had a minimal influence on daily feed intake. Those birds fed diet 1 (provided Ca by limestone) ate less total feed compared to those birds fed diets 3 (contained the Ca source as two-thirds oyster shell plus one-third limestone) and 4 (calcium provided by oyster shell). Feed consumption increased with increasing level of oyster shell in the diet. Scott et al. (1971) found that replacing two-thirds of the particulate limestone in laying hen diets, on an equal weight basis, with oyster shell, produced an increase in feed intake. Mbrtality- Mortality during the trial ranged from 22 to 30 turkeys per experimental diet. In this experiment the level of mortality was normal and did not seem to be related to dietary treatment. Most of the mortality was from aortic rupture and culling due to leg disorders and pendulous crops. Stevens et al. (1988) reported that mortality in turkeys is highly related to aortic rupture. Numbers of mortality in this experiment is shown in Table 6. 41 42 Table 6. The Effect of Different Calcium Sources on Feed Consumption , Numbers of Mortality, and Numbers of Leg Deformities in Tom Turkeys. Diet* Feed Consumption Mortality leg deformities 1 8189.0 lb 23 5 2 8331.0 1b 30 6 3 8400.0 lb 26 6 4 8774.0 lb 22 5 Diet* 1:Basal Ration, All Limestone: Diet 2. Basal Ration, 1/3 Oyster Shell, 2/3 Limestone; Diet 3. Basal Ration, 2/3 Oyster Shell, 1/3 Limestone; Diet 4. Basal Ration, All Oyster Shell. Feed Conversion- Feed conversion at 18 weeks of age varied from 2.540 to 2.578 kg of feed per kg of weight gain for the various dietary treatments (Table 7). There were no significant differences (p>.05) between dietary treatments. 43 Table 7. Feed Conversion at 18 Weeks of Age for Tom Turkeys on Varying Levels of Oyster Shell and Limestone Treatments* Replication 1 2 3 4 1 2.429 2.485 2.591 2.473 2 2.569 2.634 2.589 2.525 3 2.596 2.561 2.508 2.564 4 2.565 2.563 2.633 2.669 Average 2.540 2.561 2.578 2.557 Treatment 1. Basal Ration, All Limestone Treatment 2. Basal Ration, 1/3 Oyster Shell, 2/3 Limestone Treatment 3. Basal Ration, 2/3 Oyster Shell, 1/3 Limestone Treatment 4. Basal Ration, All Oyster Shell Incidence of Leg Disorders- Leg disorders (Table 6) were observed during the experimental period. Most of the leg disorders were described as slight to moderate cases of twisted legs with some rotated tibias. Affected birds spent more time sitting than unaffected ones and walked with a typically ataxic gait. The same observation was reported by Sanger (1974). However, incidence of leg disorders was not affected by dietary experiment (p>.005). Although no statistical analysis were conducted on the subjective leg measurements, there appears no question that the incidence of both deformed legs and poor mobility were not related to the dietary experiment. In this study, the incidence of lameness was calculated on a per experimental diet basis by including any birds with leg abnormalities 44 that died during the study. However, the level of limestone and oyster shell in diets did not appear to enhance or reduce any particular leg problems when combined in different levels. Neither the incidence of leg weakness nor mortality were significantly influenced by variations of limestone and oyster shell in the experimental diet. Body Weight- Average body weights of the turkeys at 1, 28, 56, and 126 day of age are presented in Tables 8-11. Table 8. Average Body Weight at Various Ages of Male Turkeys Fed Varying levels of Oyster-shell and Limestone Treatment* 1 """" 5' s- """" Emmi; (9) (1‘9) (kg) “(9) "m"; """"""""" 333;;"""ITISE""ZTSSS"'IST§EE 2 54.321 1.121 4.085 14.477 3 54.713 1.110 4.255 13.957 4 55.344 1.123 3.980 14.139 Treatment* 1. Basal Ration, All Limestone; Treatment 2. Basal Ration, 1/3 Oyster Shell, 2/3 Limestone; Treatment 3. Basal Ration, 2/3 Oyster Shell, 1/3 Limestone;Treatment 4. Basal Ration, All Oyster Shell. 45 Body weights were not significantly affected (p>0.05) by dietary experiment at 28 days of age. Diet 3 (2/3 oyster shell and 1/3 limestone) induced heavier body weight at 56 days and being significantly larger than treatment 4 (all added Ca as oyster shell). All other average body weights at this age were not significantly different from each other. However, this significant difference did not occur at the 126 day weigh period, where the average body weights ranged from 13.758 to 14.477 kg. The average body weights obtained in this trial are similar to commercial body weights at the various ages, perhaps slightly larger. The significant difference in the average body weights between groups 3 and 4 at 56 days of age cannot be explained except by chance. No other significant differences in weight were observed at any other age during this trial. Table 9. Average Body Weight of Tom Turkeys at 28 Days in Kg Treat.* 1 Treat. 2 Treat. 3 Treat. 4 Rep. 1 1.226 1.190 1.141 1.181 2 1.095 1.099 1.123 1.082 3 1.063 1.089 1.108 1.136 4 1.144 1.107 1.069 1.095 Aveg. 1.132 1.121 1.110 1.123 Treatment* 1. Basal Ration, All Limestone; Treatment 2. Basal Ration, 1/3 Oyster Shell, 2/3 Limestone; Treatment 3. Basal Ration, 2/3 Oyster Shell, 1/3 Limestone; Treatment 4. Basal Ration, All Oyster Shell 46 Analysis of Variance 28 Day Body Weight Source SS Sf MS E Treatments 0.000962 3 3.2067x10'4 0.3092 Error 0.0093345 9 0.001037 Table 10. Average Body Weight of Tom Turkeys at 56 Days in Kg Treat.* 1 Treat. 2 Treat. 3 Treat. 4 Rep. 1 3.968 4.210 4.228 4.124 2 4.049 4.125 4.293 3.855 3 4.025 3.883 4.288 3.966 4 4.170 4.121 4.213 3.974 Aveg. 4.053 4.085 4.255 3.980 Treatment* 1. Basal Ration, All Limestone; Treatment 2. Basal Ration, 1/3 Oyster Shell 2/3 Limestone; Treatment 3. Basal Ration, 2/3 Oyster Shell 1/3 Limestone; Treatment 4. Basal Ration, All Oyster Shell Analysis of Variance 56 Days Body Weight Sgurge SS 9f MS 2 Treatments 0.1629189 3 0.0543063 4.82528 * Error 0.10129081 9 0.011254534 *: Significant at the 0.05% level of probability. 47 Table 11. Average Body Weight of Tom Turkeys at 126 Day in Kg Treat.* 1 Treat. 2 Treat. 3 Treat. 4 Rep. 1 13.854 16.105 14.093 14.503 2 13.638 14.227 14.275 13.970 3 13.107 13.166 14.336 13.711 4 14.599 14.615 13.126 14.396 X 13.758 14.477 13.957 14.139 Treatment* 1.Basal Ration, All Limestone; Treatment 2. Basal Ration, 1/3 Oyster Shell 2/3 Limestone; Treatment 3. Basal Ration, 2/3 Oyster Shell 1/3 Limestone; Tretment 4. Basal Ration, All Oyster Shell = average. Analysis of Variance 126 Day Body Weight Segree SS. if MS E Treatment 5.4407 3 1.8136 0.6783 Error 24.0646 9 2.6739 Tibia ASh- The results of tibia ash determinations in turkeys at 2, 4, 6, and 12 weeks of age are shown in Table 12. There were no significant differences between separately analyzed data at each age (p>0.05). The percentage ash contents of dry fat free tibias at 12 weeks of age for diets 1, 2, 3, and 4 were 55.5, 55.68, 55.13, and 54.8 respectively. Tibia ash percentage increased from 48 approximately 50% as the birds aged from 14 days to 84 days. This would be expected in normal bone development. Final body weight and tibia ash is shown in Table 13. No correlation between body weight and tibia ash was found. Toe Ash- The percentage of dry, fat-free toe (first and second fragments of the middle toe) ash at 4, 6, and 12 weeks of age are shown in Table 12. The percentage ash contents of dry fat free toe at 12 weeks of age for diets 1, 2, 3, and 4 were 48.5, 49.3, 48.6, and 49.1 respectively. There was no significant difference in toe ash (p>.05) between the diets at the various ages. A plot of tibia and toe ash percentages of all ages is shown in Figure 1. Visual and statistical inspection of the plot reveals that there is a high correlation (r=0.727) between tibia and toe ash. This result is in agreement with the finding of Yoshida and Hoshii (1983) who found a: significant correlation between tibia and toe ash in the chicken. Yang et al. (1973) recommended the use of toe ash as a major criterion for determining dietary adequacy and also showed that toe ash gave the greatest precision in a short term study of the bioavailability of different sources of vitamin D3. Reduced time consumption and labor were reported to be the reasons for the use of toe ash instead of tibia ash as 49 a criterion for determining vitamin D3 potency (Baird and McMillan 1942). 50 Table 12. Percent Ash in Tibias and toes* from Male Turkeys Fed Diets Containing Different Sources of Calcium Diet** WK 2 4 6 12 ————————————————————————— 96_--_-____.._..-_---_ 1 Tibia 51.40 51.11 54.30 55.50 Toe __ 43.80 47.60 48.50 2 Tibia 50.20 51.00 53.96 55.68 Toe __ 42.30 46.90 49.30 3 Tibia 51.60 51.21 54.73 55.13 Toe __ 46.20 47.70 48.60 4 Tibia 50.60 51.12 54.13 54.80 Toe 44.20 47.60 49.10 Toe*. Toe consist of first and second fragments of middle toe. Diet** 1. Basal Ration, All Limestone; Diet. 2. Basal Ration, 1/3 Oyster Shell, 2/3 Limestone; Diet 3. Basal Ration, 2/3 Oyster' Shell, 1/3 Limestone; Diet ‘4. Basal Ration, All Oyster Shell Table 13. Final Body Weights and Total Percent Tibia Ash of Tom Turkeys Receiving different levels of Oyster Shell and Limestone As Ca Sources. Diet* Final Bw Total Bone Ash Kg % 1 13.758 55.50 2 14.477 55.68 3 13.957 55.13 4 14.139 54.80 Diet*1. Basal Ration, All Limestone; Diet 2. Basal Ration, 1/3 Oystr Shell, 2/3 Limestone; Diet 3. Basal Ration, 2/3 Oyster Shell, 1/3 Limestone; Diet 4. Basal Ration, All Oyster Shell 51 Figure 1. Comparison of Percent Tiba Ash and Toe Ash in Tom Turkeys at 4, 6, and 12 weeks of age 9...; {- ............................................................................ ' ------------ ;. .- . r, : ‘ :p : o. .. g . .‘ . p- . _. . c—i ’ . I ' _ ’3'“: r..: ......................................................................... . ................ L . a I . ’ . j , : z . _J .0 . ‘5 , ’,- g: - '.‘flga' ‘ o- — .................................................................. .. .neozfl. oooooooooooooo — Dc‘U‘ _ . - . ‘ . I. . . . A . ’0‘ Ex’ . . .- .- . r , 1 ' . I '9 ' . ' o I O . OP 0 ’ o . a ' . . , .I "'" . 3_.I.. ..'. ...................... ..'. :2..-..' ............. 5 .................... .. *— &U'Q.J I I ’ . . 'A ./ P ' L . .. "r .r ,. L " . a" ’ I. - p " A :- . t ”'1’: !‘ . ‘ .- I i x‘i- " ' ' .. ' a : Loe’ Fee-‘- eeeeeeeee ’0’ eeeeeee ’votooe‘ooe! eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee .- OV . ” I U U a . f”. p ! o- 'L I 4" :p’ ' D : I a - ’ I 9.49 p ..... ‘ ooooooooooooooooooooooo a.coco-ooeeoe-eee-o-oe-ooe-eeeoeoeooooeeoeoeoocoo-oeoecoo-o'e- ' a H ' r ‘0 ‘ 2'? 9.11 a. 4.: a. 1 as N do ‘7 9.3: To 9) The Since there is not very much deviation from the straight line considering the small difference between high and low ash, it appears that the agreement between bone ash and toe ash is very good. This is substantiated by a determination of the coefficient of correlation between these two values. This was (r=0.727) which is relatively highly significantly correlated. SUMMARY Much research has been done to evaluate the difference in utilization of the Ca from limestone and oyster shell for egg formation and body ‘weight. Kennard (1925) and Brister et al. (1981) found that oyster shell is superior to limestone. Hart et al. (1927) recorded increased egg production and Scott et al. (1971) found an increase in shell breaking strength with oyster shell when compared with limestone. On the other hand, Buckner et al. (1928) concluded that limestone or oyster shell serve equally as well as sources of calcium for laying hens. Similarly, Wait (1921) and Arvat et al. (1973) found no differences in utilization of Ca from limestone and oyster shell for egg shell formation. In this experiment, results obtained showed that there is no significant influence (p>0.05) of dietary levels of limestone and oyster shell on the body weights at 28 days of age. Birds fed diet 3 at 56 days of age were significantly (p<0.05) different from those birds fed diet 4, but this significant difference did not occur at the 126 day weigh period. However, there were no significant differences (p>0.05) between dietary tratments on leg weakness. The percentage of tibia ash and toe ash were found to be correlated (r=0.727), but no correlation was found between dietary treatment and mortality. 52 53 Knowledge of leg disorders in poultry, attained through experiments and observation, has been the means by which such disorders have been reduced substantially over the last five decades. Based on this research, it has become evident that a variety of integrated solutions are required to eliminate leg abnormalities, drawing on disciplines as diverse as physiology, genetics, nutrition, pathology, environment, and management. LIST OF REFERENCES LIST OF REFERENCES Abbot,W.W., J. R. Couch, and R. L. Atkinson, 1969. The incidence of foot pad dermatitis in young turkeys fed high levels of soybean meal. Poult. Sci. 48:2186-2188. Adams, R. L., and W. J. Stadelman, 1978. Effect of delay of growth on leg weakness of tom turkeys. XVI World’s Poult. Congress 4:559-565. Anderson, J. 0., and R. E. Warnick, 1970. 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