Replacing ground corn with soyhulls plus palmitic acid in low metabolizable protein diets with or without rumen-protected amino acids: Effects on production and nutrient utilization in dairy cows

• DOI: 10.3168/jds.2022-22270
• Publication Date: 2023-04-25T19:39:06Z
• Authors: Y. Zang; L.H.P. Silva; Y.C. Geng; M.J. Lange; M.A. Zambom; A.F. Brito
• Keywords: Latin square; Total mixed ration; Neutral Detergent Fiber

We previously observed that diets with reduced starch concentration decreased yields of milk and protein in dairy cows fed low metabolizable diets. Supplementation reduced-starch a lipid source may attenuate or eliminate production losses. Our objective was to investigate the effects partially replacing ground corn soyhulls plus palmitic acid-enriched supplement on dry matter (DM) intake, yield composition, plasma AA concentration, N energy utilization (mean = -68 g/d balance) without rumen-protected Met, Lys, His (RP-MLH). Sixteen multiparous Holstein averaging ± standard deviation) 112 28 d milk, 724 44 kg body weight, 46 5 kg/d beginning study were used replicated 4 × Latin square design 2 factorial arrangement treatments. Each period lasted 21 d, consisting 14 for diet adaptation 7 data sample collection. Diets as follows: (1) high (HS), (2) HS RP-MLH (HS+AA), (3) (RSPA), (4) RSPA (RSPA+AA). The contained (DM basis) 26% 7% soyhulls, had 10% corn, 22% 1.5% acid. averaged 32.6% 4% ether extract, while extract concentrations 21.7 5.9%, respectively. All 40% silage, 5% mixed-mostly grass haylage, hay, 50% concentrate. did not affect DM intake yield. Contrarily, feeding RSPA+AA increased energy-corrected (47.0 vs. 44.8 kg/d) fat (1.65 1.50 compared HS+AA. Milk tended decrease when supplemented HS, but no change seen added RS (starch level interaction). urea increased, efficiency versus Apparent total-tract digestibilites crude neutral detergent fiber, well urinary total excretion, greater offered than Plasma Met supplemental RP-MLH. Intake gross digestible output all In summary, acid fiber digestibility maintained yield, elevated excretion.