Calving date and wintering system effects on cow and calf performance I: A systems approach to beef production in the Nebraska Sandhills

A 4-yr study using 217 cows/yr (3/4 Red Angus, 1/4 Simmental) evaluated effects of calving date and wintering system on cow and calf performance from birth to harvest. Cows were assigned to 1 of 5 treatments: 1) March (Mar) calving cows wintered on native range, 2) Mar calving cows wintered on corn residue, 3) June (Jun) calving cows wintered on native range, 4) Jun calving cows wintered on corn residue, and 5) August (Aug) calving cows wintered on corn residue. Steers born in Mar entered the feedlot at weaning (calf-fed). Steers and heifers born in Jun and Aug were divided equally into 2 postweaning management treatments. Half entered the feedlot immediately after weaning (calf-fed), and half grazed cool season meadow and entered the feedlot as yearlings. Precalving BW (P < 0.01) and BCS (P < 0.01) were greatest for Aug-calving cows and least for Mar-calving cows. Cow BCS at weaning was similar (P = 0.15) among calving dates. Cow BCS was not affected (P > 0.22) by wintering treatment. Pregnancy rates were similar among calving dates (P = 0.37) and wintering systems (P = 0.53). Adjusted 205-d weaning BW were greatest (P ≤ 0.001) for calves born in Mar, intermediate for calves born in Aug, and least for calves born in Jun but not affected (P = 0.56) by wintering system. Carcass weight of calf-fed steers was greatest (P = 0.03) for those born in Jun, followed by Aug, and least for Mar. Feedlot performance was not affected (P > 0.10) by cow wintering system. Yearlings had greater (P < 0.001) feedlot DMI and ADG than calf-feds. Calving date but not wintering system affected cow BW and BCS, and affected calf BW gain from birth to harvest.