February 2026 NEBRASKA CATTLEMAN 25 combination, these results demonstrated that late gestational nutrient restriction is inconsistent in reducing fetal growth, which appears to be driven more by placental size than uterine blood flow. While calf birth weight and gestation length were unaffected in this study, nutrient-restricted dams had less vigorous calves that were slower to stand and 40 percent less colostrum yield. Colostrum of nutrient-restricted females was more concentrated with immunoglobulin G, and calf 48-h serum immunoglobulin G indicated that calves of both treatments had successful passive transfer of immunity. Colostrum of nutrient-restricted females had less total lactose, but similar total protein and fat compared with control females. There was no neonatal calf death loss due to treatment; however, this was likely because females were monitored continuously during the calving season for research purposes. Even when females were fed to meet their energy and protein requirements during lactation, late gestational nutrient restriction reduced milk yield by 15 percent and decreased milk protein concentration during the first 150 days of lactation. Lower milk production was partially explained by a 19 percent reduction in blood flow supplying the mammary gland during this time. By day 21 of lactation, metabolic status of previously nutrient-restricted dams had returned to concentrations similar to control dams. During lactation, previously nutrient-restricted females gained maternal weight faster and increased body condition. Still, previously nutrient-restricted dams had not fully recovered by weaning, as they weighed 37 pounds less and were 0.7 lower body condition score. Females in both treatments were similarly successful in rebreeding for a second calf and comparable to industry averages for conception rate. Less total lactose, protein and fat provided by the milk resulted in calf body weight diverging by 42 days of age. Calves born to nutrient-restricted dams remained smaller through weaning, when they weighed 59 pounds less than control calves (Figure 2). Interestingly, calf metabolic status Figure 1. Effects of late gestational nutrient restriction on dam and offspring outcomes in the first parity. Figure 2. Effect of late gestational nutrient restriction on calf body weight (BW) from birth until weaning. Solid circles (●) represent calves born to control dams and open circles (○) represent calves born to nutrient-restricted dams. *Treatment means differ (P ≤ 0.05). CONTINUED ON PAGE 26
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