Submitted to: Professional Animal Scientist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2001
Publication Date: 3/15/2001
Citation: BELLOWS, R.A., GRINGS, E.E., SIMMS, D.D., GEARY, T.W., BERGMAN, J.W. EFFECTS OF FEEDING SUPPLEMENTAL FAT DURING GESTATION TO FIRST-CALF BEEF HEIFERS. PROFESSIONAL ANIMAL SCIENTIST. 2001. v. 17. p. 81-89. Interpretive Summary: This research demonstrates the beneficial effects of feeding supplemental vegetable fat to pregnant beef heifers during gestation and the subsequent positive responses in both pregnancy rate and calf weaning weight. Dietary fat, and possibly more specifically unsaturated fatty acids, are important components of the "reproductive fuel" required for optimal reproductive activity and should be given full consideration as components of rations formulated to improve reproductive performance in beef cattle.
Technical Abstract: Study 1. Pregnant crossbred, first-calf heifers (n=149) received one of four gestation diets: control (C), or added safflower seeds (SAFF), raw soybeans (SOY), or sunflower seeds (SUN). Diets were approximately equal in protein and energy content and contained 2.4, 4.7, 3.8, or 5.1% fat, respectively and were fed for the last 65.3 +/- 4.6 d precalving. Effects of fat supplementation on dam body weights or condition scores and birth weight, calving difficulty, and dam estrous cyclicity at the beginning of the breeding season were nonsignificant. Fat supplemented dams had greater pregnancy rates (P<0.05) and fall calf weights (P=0.08): C, 79%, 182.4 kg; SAFF 94%, 194.9 kg; SOY, 90%, 197.7 kg; SUN, 91%, 196.8 kg. Study 2. Pregnant crossbred, first-calf heifers (n=83) were assigned to one of two gestation diets: control (C2) or added sunflower seeds (SUN2). Diets were approximately equal in protein and energy content, contained 2.2% and 6.5% fat, C2 and SUN2, respectively, and were fed for the last 68.2 +/- 5.5 d before calving. Blood samples were analyzed for IGF, glucose, and NEFA. Diet effects on dam body weights, condition scores, estrous cyclicity at beginning of breeding, and pregnancy percentage were nonsignificant. Calf birth weights from SUN2 dams tended (P=0.06) to be greater. Diet effects on blood components were nonsignificant except for NEFA concentrations tending to be lower in SUN2 dams at the initial (P=0.08) and mid gestation (P=0.06) sampling. We conclude dietary fat is an important "reproductive fuel," and the effects of supplemental fat fed during gestation can be masked when adequate nutrients are available during the postpartum and breeding periods.