Impacts of early weaning and winter feeding strategy on cow-calf performance

Abstract Text: Low-input winter feeding programs and early weaning of calves can reduce annual feed costs and maintain cow performance; however, few reports in the literature examine long-term responses or the interaction of these management strategies on the cow herd.  The objective of this study was to evaluate the effects of early versus normal weaning (WEAN) in conjunction with two winter feeding strategies (WINTER) on cow BW, body condition score (BCS), reproductive performance, and calf performance. Mixed-age Angus × Simmental cows (n = 239) were used in a 6-year study conducted at the SDSU Antelope Livestock and Range Research Station.  Cows were randomly assigned to one of two weaning treatments (early wean [EW] in August or normal wean [NW] in November).  Following normal weaning and through calving, cows were randomly assigned to one of two feeding treatments: wintered on native range with access to a distillers-grains-based supplement (low-input winter feeding [LOW]) or fed mixed alfalfa-grass hay with the option of grazing native range (high-input winter feeding [HIGH]).  After initial treatment assignment, cows remained in original treatments throughout the project. Cow BW and BCS were recorded before calving, at initiation of breeding, at early weaning, and at normal weaning.  Reproductive response, calf performance, and culling rates were recorded.  Cow BW and BCS were greater (P < 0.05) for EW vs. NW cows at normal weaning every year.  Cows on the EW treatment lost more BW from calving to breeding compared to the NW treatment (mean loss 28.5 vs 7.0 ± 3.9 kg; P = 0.0001).  There was a WEAN × WINTER interaction (P = 0.05) for pregnancy rate (98% for NW HIGH vs. 94% NW LOW cows, with EW treatment intermediate).  Mean calving date was 3 d later (P < 0.05) by cows on EW HIGH than EW LOW or NW HIGH.  Calving and weaning rates did not differ (P > 0.70) among WEAN or WINTER treatments. Calf ADG from birth to EW tended (P = 0.06) to be greater for EW vs. NW calves (1.09 vs. 1.06 ± 0.015 kg/d, respectively).  Cows on LOW had greater (P < 0.05) cull rates and were on study a shorter amount of time compared to cows on HIGH.  Early vs. normal weaning maintained cow BW and BCS at greater levels throughout the study.  WEAN and WINTER treatments rarely interacted in their influence on performance.

Keywords: Early weaning, DDGS, hay, winter feeding