74 Production Responses of an Alternative Beef Cow-calf System

Abstract

\n A two-yr study was conducted to measure reproductive responses of an alternative cow-calf production system. Multiparous, crossbred cows (n = 160; average age = 5.7 ± 2.8 yrs-old) were utilized, per yr, in a generalized randomized bock design and unstructured treatment design. In yr one, cows were blocked by origin source and age, randomly assigned to one of two production systems, each with four replicates (n = 20 cows/rep). Once allotted to treatment and replicate, cows remained in assigned treatment for the duration of their productive life. Treatments were: 1) traditional extensive spring calving system utilizing perennial pasture and corn residue grazing (TRAD); 2) alternative fall-calving system utilizing confinement, summer-planted oats, and corn residue grazing (ALT). Breeding body condition score (BCS) was greater (P < 0.01) for TRAD compared to ALT (6.45 vs. 5.47 ± 0.159, respectively). There were no differences (P ≥ 0.24) in conception rates (93.86 vs. 94.14 ± 2.26 %), pregnancy loss (4.37 vs. 5.62 ± 1.86 %), calving rates (89.50 vs. 88.49 ± 3.06 %), and weaning rates (86.88 vs. 82.50 ± 3.08 %) for TRAD and ALT, respectively. There was no difference (P = 0.47) in calf body weight at birth (40 vs. 39 ± 1.0 kg) for TRAD and ALT, respectively. Weaning BCS was greater (P < 0.01) for TRAD compared to ALT (5.71 vs. 5.27 ± 0.048). Calves in the TRAD system had greater (P < 0.001) wean BW (237 vs. 185 ± 3.7 kg) compared to ALT calves. Cows from TRAD system had greater (P < 0.001) kg weaned per cow exposed to bulls (208 vs. 151 ± 6.3 kg) compared to ALT cows. Results indicate no difference in reproductive performance among systems. The extensive spring-calving system produced heavier calves at weaning, leading to more kg of calf weaned per cow exposed.