Date of this Version
Woita, N. M. 2022. Using strategic supplementation to enhance cow/calf productivity in summer calving herds in the Nebraska Sandhills. M. S. Thesis, University of Nebraska-Lincoln, Lincoln.
Young range beef cows consuming low-quality forage may result in an imbalance of energy and metabolizable protein, which can negatively affect the nutrient status of the cow and reproductive performance. In a 2-yr study conducted at Gudmundsen Sandhills Laboratory near Whitman, NE, 2- and 3-yr-old May-calving range cows (n = 181) grazing native range were individually supplemented daily with one of four supplements: 1) mineral with a target intake of 113 g/d (MIN), 2) MIN with 200 mg per head of Rumensin to with a target intake of 113 g/d (RUM), 3) MIN with a 226 g/d of high RUP sources with a target intake of 340 g/d (RUP), or 4) dried distiller grains at a rate of 907 g/d (DDG). Each year, supplementation started approximately 30 d before the breeding season and continued throughout the 45-d breeding season. Cow body weight (BW), body condition score (BCS), and blood samples were taken biweekly beginning 40 d postpartum and ending 125 d postpartum. Milk production was collected at approximately 60 d postpartum. Cow BW, BW change, and BCS were not different (P ≥ 0.29) between supplementation treatment. Pregnancy rates were 82, 83, 92, and 89% for MIN, RUM, RUP, and DDG fed cows, respectively (P = 0.76). Calf BW at birth, 60-d BW, and 205-d BW were not affected (P ≥ 0.19) by dam supplementation. Cows receiving DDG had increased (P = 0.05) circulating serum glucose concentrations compared to MIN, with no difference between RUM and RUP. Cows receiving DDG and RUP had increased (P = 0.01) circulating serum urea nitrogen concentrations. Postpartum supplements did not affect (P = 0.13) circulating serum non-esterified fatty acid concentration. Milk production was not affected (P ≥ 0.11) by postpartum supplements. The results from this study suggest that supplying RUP, energy, or ionophores did not increase cow BW or BCS but, cows were able to maintain these metrics. However, additional protein and energy tended to increase glucose and serum urea nitrogen. The number of years and cows in this study may not have been enough to find differences among supplementation strategies; however, additional years and data may change observed results in this study.
Advisors: J. Travis Mulliniks and Kacie L. McCarthy