Effect of dietary energy on milk production and metabolic hormones in thin, primiparous beef heifers.

• DOI: 10.2527/2000.783530x
• Publication Date: 2016-08-09T16:48:45Z
• Authors: D L Lalman; J E Williams; B W Hess; M G Thomas; D H Keisler
• Keywords: 2. Zero hunger; Neuropeptides; 0402 animal and dairy science; 04 agricultural and veterinary sciences; Animal Feed; Parity; Pregnancy; Growth Hormone; Body Composition; Animals; Homeostasis; Insulin; Lactation; Animal Nutritional Physiological Phenomena; Cattle; Female; Neuropeptide Y; Insulin-Like Growth Factor I; Energy Metabolism

Thirty-six primiparous heifers were used to determine the effect of dietary energy on postpartum interval, milk production, serum concentrations insulin, insulin-like growth factor I (IGF-I), hormone, and cerebrospinal fluid (CSF) neuropeptide-Y (NPY). Low-quality hay was fed during last trimester pregnancy achieve suboptimal calving weight (370 +/- 5 kg) condition score (4.0 .1). After calving, cows allotted one four treatments that differed in metabolizable energy. Experimental diets at 2.5% shrunk body formulated provide 1.8 (low), 2.1 (maintenance), 2.4 (maintenance high), or 2.7 (high) Mcal ME/kg DM. Daily production estimated approximately 30, 60, 90 d postpartum. Condition change defined as from As intake increased, (P < .001), IGF-I .001) insulin .01) increased interval decreased = .04). No relationship existed between CSF concentration NPY > positively associated with (r .71, P .001; r .38, .02, respectively) negatively GH -.67, .001). Weight did not differ .10) among treatments. Increasing a curvilinear increase yield .04) percentage fat .03) linear available for production. Greater 30 longer .34, .05). In conclusion, greater proportion net is partitioned maternal tissue realimentation when receive high compared low-, maintenance-, moderate-energy diets.