Effects of maternal winter vs. year-round supplementation of protein and energy on postnatal growth, immune function, and carcass characteristics of Bos indicus-influenced beef offspring

Maternal prepartum supplementation of protein and energy and body condition score modulated the performance of Bos indicus-influenced cow-calf pairs

Retrospective analyses were performed on a dataset of 1188 fall-calving, Brangus cow-calf pairs. Analyses 1 sorted cows according to their initial body condition score (BCS < 5 vs. ≥ 5) and whether they received (SUP) or not (NOSUP) prepartum supplementation of protein and energy. Analyses 2 sorted cows according to their calving BCS (BCS < 5 or ≥ 5) and BCS change from calving until the start of the breeding season (lost, maintained, or gained). Cows were not estrus synchronized and were assigned to natural breeding for 90 days. Prepartum supplementation increased (P = 0.04) pregnancy percentage in cows with initial BCS < 5 but not (P = 0.20) with initial BCS ≥ 5. Calf weaning weight was greatest (P ≤ 0.04) for calves born from SUP cows with an initial BCS ≥ 5 and did not differ (P ≥ 0.56) among all remaining groups. Among cows with calving BCS < 5, pregnancy percentage were less (P = 0.05) for cows that lost vs. maintained/gained BCS. Postpartum BCS change did not (P ≥ 0.16) impact pregnancy percentage of cows calving at BCS ≥ 5. Calf weaning weight increased (P < 0.01) for cows calving with BCS ≥ 5 vs. < 5 and was not impacted (P = 0.47) by postpartum BCS change. Therefore, precalving supplementation improved reproduction of cows with BCS below optimal and weaning weight of calves born from cows with BCS above optimal, whereas calving BCS was the major factor affecting postpartum BCS change and cow reproductive performance.

Frequency of maternal supplementation of energy and protein during late gestation modulates preweaning growth of their beef offspring

This study evaluated the effects of decreasing the frequency of dried distillers grains (DDG) supplementation during third trimester of gestation on cow physiology and offspring preweaning growth. At 201 ± 7 d prepartum (day 0 of the study), 120 Brangus crossbred cows were stratified by body weight (BW = 543 ± 53 kg) and body condition score (BCS = 5.47 ± 0.73), and then assigned randomly to 1 of 20 bahiagrass (Paspalum notatum) pastures (six cows and 4.7 ha/pasture). Treatments were randomly assigned to pastures (five pastures/treatment) and consisted of cows offered no DDG supplementation (NOSUP) or precalving supplementation of DDG dry matter at 1 kg/cow daily (7×), 2.33 kg/cow every Monday, Wednesday, and Friday (3×), or 7 kg/cow every Monday (1×) from day 0 to 77. All cows assigned to DDG supplementation received the same total amount of DDG dry matter (77 kg/cow) from day 0 to 77. All cow-calf pairs were managed similarly from day 77 until calf weaning (day 342). Supplementation frequency did not impact (P ≥ 0.16) any forage or cow reproduction data. Cow BCS on days 77, 140, and 342 did not differ among 1×, 3×, and 7× cows (P ≥ 0.29) but all supplemented cows, regardless of supplementation frequency, had greater BCS on days 77, 140, and 342 compared to NOSUP cows (P ≤ 0.04). Cows offered 1× supplementation had greater plasma concentrations of IGF-1 on days 35 and 140 compared to NOSUP, 3× and 7× cows (P ≤ 0.04), whereas 3× and 7× cows had greater plasma concentrations of IGF-1 on day 35 compared to NOSUP cows (P ≤ 0.005). Average plasma concentrations of glucose did not differ among 1×, 3×, and 7× cows (P ≥ 0.44), but all supplemented cows had greater plasma concentrations of glucose compared to NOSUP cows (P ≤ 0.05). Birth BW of the first offspring did not differ between 3× and 7× calves (P = 0.54) but both groups were heavier at birth compared to NOSUP calves (P ≤ 0.05). On day 342, calves born from 7× cows were the heaviest (P ≤ 0.05), whereas calves born from 1× and 3× cows had similar BW (P = 0.97) but both groups were heavier compared to calves born from NOSUP cows (P ≤ 0.05). In summary, decreasing the frequency of DDG supplementation, from daily to one or three times weekly, during third trimester of gestation of beef cows did not impact cow BCS but altered maternal plasma concentrations of IGF-1 and glucose, leading to reduced offspring preweaning growth.

Monensin supplementation during late gestation of beef cows alters maternal plasma concentrations of insulin-like growth factors 1 and 2 and enhances offspring preweaning growth

This study evaluated the effects of maternal prepartum supplementation of dried distillers grains (DDG), with or without monensin addition, on maternal performance and physiology and offspring preweaning growth. On day 0 (approximately 197 ± 4 d prepartum), 150 multiparous, Brangus crossbred beef cows were ranked by their initial body weight (BW; 524 ± 51 kg) and body condition score (BCS; 5.0 ± 0.63), and then randomly assigned into one of 15 bahiagrass (Paspalum notatum) pastures (10 cows and 8.1 ha/pasture). Maternal treatments were randomly assigned to pastures (5 pastures/treatment) and consisted of no prepartum supplementation of DDG (NOSUP) or supplementation of DDG at 1 kg/cow/d (dry matter basis; DM) added with 0 mg (SUP) or 200 mg/d of monensin (SUPMO) from days 0 to 77. Effects of maternal treatment and maternal treatment × day of the study were not detected (P ≥ 0.63) for any forage data. Cow BCS on day 35 and near calving (day 77) did not differ (P ≥ 0.19) between SUP and SUPMO cows but both groups had greater (P ≤ 0.001) BCS compared with NOSUP cows. Cow BCS at the start of the breeding season (day 142) and on day 168 were the greatest (P < 0.0001) for SUPMO cows, least for NOSUP cows, and intermediate (P ≤ 0.02) for SUP cows. Maternal plasma concentrations of glucose did not differ (P ≥ 0.25) among treatments. Plasma concentrations of insulin-like growth factor 1 (IGF-1) on day 77 were the least for NOSUP cows (P ≤ 0.05) and did not differ (P = 0.66) between SUP and SUPMO cows, whereas plasma concentrations of IGF-2 on days 35 and 77 were greatest (P ≤ 0.05) for SUPMO cows and did not differ (P ≥ 0.60) between NOSUP and SUP cows. Birth BW of first offspring did not differ (P = 0.77) between SUP and SUPMO calves but NOSUP calves were lighter at birth (P ≤ 0.05) compared with SUP and SUPMO calves. Percentage of cows pregnant with a second offspring did not differ (P = 0.72) between SUP and SUPMO cows and were the least for NOSUP cows (P ≤ 0.05). First offspring BW at weaning (day 325) was greatest (P ≤ 0.05) for SUPMO calves, least for NOSUP calves, and intermediate for SUP calves. Therefore, adding monensin into prepartum DDG supplements for Bos indicus-influenced beef cows did not increase cow prepartum BCS but led to greatest offspring preweaning growth, likely by modulating maternal plasma concentrations of IGF-1 and IGF-2 during gestation.