Interpretive Summary: Late Gestation Supplementation in Beef

By: Jackie Walling
Courtesy of American Society of Animal Science

A recent article published in Translational Animal Science investigated the effects and interaction of weaning date and late gestation supplementation on productivity in a spring calving system. Measures included cow reproductive performance, heifer progeny growth, and reproduction performance, and steer progeny growth, feedlot performance, and carcass characteristics.

Cows were weaned in October (OCT) or December (DEC). Grazing treatments consisted of dormant upland range with a supplement amount (32% crude protein at WR0=0, WR1=.41, or WR2=.82 kg/cow/d) or grazing corn residue with no supplement (CR).

General cow performance resulted in OCT maintaining a greater body condition score (BCS) than DEC cows from October to December. Grazing treatment results followed a pattern of increasing nutritional plane: WR0 had the lowest BCS and body weight (BW), and CR had the greatest. BCS of cows going into winter seemed to influence pregnancy rate, calving rate, and weaning rate more than weaning time or grazing treatment.

Calf performance measured in December indicated an interaction between weaning and grazing treatments. OCT had the lowest BW in October for WR0 dams while DEC followed the nutritional plane. Weaning calves in October allowed dams to enter winter grazing with a greater BCS.

Heifer performance showed the percentage cycling and breeding rates were similar among treatments. BW may have fluctuated based on weaning time, but breeding BW was similar.

Steer performance showed OCT had greater feedlot entry BW than DEC, but average daily gain and dry matter intake was similar regardless of weaning. Steers born to dams on the higher nutritional planes had higher hot carcass weight when adjusted to equal 12th rib fat thickness.

Overall, better growth performance was seen for cows and progeny on a higher nutritional plane, but BCS going into winter may have a large influence on productivity results. Past studies have some conflicting results, especially surrounding reproduction, likely due to different management factors.

To read the full article, visit Translational Animal Science.

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