Effects of flexible prepartum supplementation strategies on cow-calf and subsequent progeny feedlot performance in a May-calving herd

Abstract

Objective

The objective of this study was to evalu- ate the effects of minimal and flexible supplementation strategies on reproduction, cow BW, and subsequent calf performance in May-calving mature cows grazing upland native range.

Materials and Methods

Cows received one of 3 sup- plementation strategies: (1) 0.227 kg per day of a 30% CP distillers-based supplement (HalfSupp), (2) 0.454 kg per day of a 30% CP distillers-based supplement (Supp), or (3) brief and intermittent supplementation of Supp at 0.454 kg/cow based on periods of acute environmental stress, such as snow cover and wet winter events, which is best described as flexible supplementation (Flex). Supple- mentation was initiated in January each year and termi- nated approximately 30 d before the start of the calving season in April. After weaning, steers grazed subirrigated meadow with a dried distillers grain supplement until May. In May, all steers grazed subirrigated meadow with- out additional supplement until August/September when steers were shipped to the feedlot. Steers were placed in a GrowSafe feeding system for the rest of the finishing feeding period.

Results and Discussion

Cow BW was not different at the initiation of supplementation in January. However, cows fed HalfSupp had a lighter BW at precalving and tended to have a lighter BW at prebreeding than their counterparts. After a 45-d breeding season, pregnancy rates were not influenced by prepartum supplementation strategies. Prepartum supplementation strategies did not influence preweaning calf BW at birth, prebreeding, and weaning. In addition, steer backgrounding BW was also not influenced by their dam’s prepartum supplementation strategy. Upon entry into the feedlot, steer feedlot perfor- mance (BW, ADG, and feed efficiency) was not influenced by their dam’s prepartum supplementation strategy. After slaughter, no carcass characteristics were affected by the dam’s prepartum supplementation strategy.

Implications and Applications

Considering the cost of prepartum supplementation, feeding a protein supple- ment just during environmentally stressful periods during gestation appears to be a viable alternative to more conventional methods and reduces winter feed costs.