Addition of fat supplements to dairy cow diets is common practice due to increases in yields of milk and milk fat. This thesis contains two studies that evaluated the effects of palmitic (C16:0), stearic (C18:0), and oleic acids (cis-9 C18:1) on lactating dairy cows. The first experiment used three commercially available products to make custom blends containing 60% C16:0 + 30% C18:0 (PA+SA) and 60% C16:0 + 30% cis-9 C18:1 (PA+OA) supplied at 1.5% diet dry matter (DM) and a non-FA supplemented control (CON) diet fed to low- and high-producing dairy cows. The PA+OA treatment increased yields of milk, milk fat, and energy corrected milk (ECM) compared with CON for high-producing cows. In contrast, the PA+SA treatment increased yields of milk fat, milk protein, ECM, and 3.5% fat-corrected milk (FCM) compared with the PA+OA treatment in low-producing cows. The second experiment evaluated different ratios of C16:0 + cis-9 C18:1 in low fat (LF; average 2.40% FA content) and high fat (HF; average 3.28% FA content) diets. Fatty acid (FA) treatments were products consisting of 80% C16:0 + 10% cis-9 C18:1 (PA) and 60% C16:0 + 30% cis-9 C18:1 (PA+OA) supplemented at 1.5% diet DM and a non-FA supplemented control (CON) diet. Interactions were observed between basal diet and FA treatment with FA treatments increasing yields of milk and lactose in the LF diet but not in the HF diet. The HF diet increased yields of milk fat and FCM and tended to increase ECM. FA treatments increased yields of milk fat, ECM, and FCM, but were not different from each other. Results from this work can help further feeding decisions for nutritionists and producers.
Read
