Perormance of Bred Heifers Fed Various Supplements During Gestation

Abstract

Three trials were conducted to evaluate the performance of heifers supplemented with various energy-based supplements while consuming a medium-quality warm-season hay during the last trimester of gestation. Trial 1 evaluated the effects of supplements that provided equal levels of CP while providing 0.1, 0.2, or 0.3% BW of corn. There were three replicates of each treatment in each of two years. Trial 2 evaluated the effects of supplements that provided equal levels of CP while providing 0, 0.15, or 0.3% BW of corn. Trial 3 evaluated the effects of feeding 1.4kg of corn, rice bran, or soybean hulls. There was no attempt to correct for different intakes of CP. Heifers received medium-quality bahiagrass (Paspalum notatum) hay free-choice during the supplementation period. There was no effect of increasing the level of corn in Trial 1 or Trial 2 on heifer BW gain during the supplementation period (P>0.13). In addition, supplementation level prior to calving did not affect heifer BW change or condition score of cows from calving until weaning (P>0.11), had no effect on fall conception rates (P>0.43), and had no effect on calf birth BW or weaning BW (P>0.34). In Trial 3, heifers supplemented with corn or soybean hulls gained more BW (9 kg) than those supplemented with rice bran (P=0.003). There was no effect of supplementation on BW change after calving (P>0.45) or on fall pregnancy rates (P=0.62) in Trial 3. In addition, calf birth and weaning BW were not affected (P>0.52) due to supplements fed in Trial 3. Results suggest that increasing the level of supplemental corn from 0 to 0.3% of BW while maintaining equal supplemental CP intake will not improve gestating heifer performance when fed medium-quality hay. The data also indicates that soybean hulls have equal feeding value to corn when fed as a supplement to heifers consuming medium-quality hay.