Longevity in beef cows is not affected by the age at first calving or calf birth weight, Washington State University and USDA researchers found.
To study factors affecting beef cow longevity, researchers used a statistical method called “survival analysis techniques.” They used data from 1,379 composite cows, born from 1982 to 1999 at the Miles City, MT, research station.
They found that females experiencing dystocia were at 60% greater risk of being culled than those calving unassisted. Also, as breeding value for cow weight increased, the risk of being culled decreased. Meanwhile, the risk of being culled increased with increasing maternal breeding value for preweaning calf gain.
Researchers noted that is likely due to the fact that cows with lower milk production may accumulate body energy reserves during lactation and weigh more at weaning than cows with higher milk production.
The analysis revealed that selection among heifers based on their birth weight, 200-day pre-weaning gain or 365-day weight had no effect on subsequent longevity. Weaning weights and yearling weights were also not predictive of her life-cycle efficiency.
The estimated heritability for longevity was low (0.14), making it difficult to genetically improve longevity in beef cattle. Researchers suggest producers instead match the genetic potential of cows for size and milk production so that rebreeding performance is not compromised (Rogers et al. 2004 J. Anim. Sci. 82:860).
Michigan State University Beef Cattle Research Update, summer issue
Feeding broiler litter to beef cattle has been banned by the U.S. Food and Drug Administration (FDA), and has left some cattlemen scrambling to find alternative feedstuffs.
Researchers at Auburn University studied the efficacy of replacing broiler litter with rice mill feed. Four experiments were conducted.
In Exp. 1, 40 Angus-based steers were fed four dietary treatments for 112 days. Diets consisted of: 1) 47% broiler litter:53% corn; 2) 60% rice mill feed:40% corn; 3) 50% rice mill feed:50% corn; and 4) 40% rice mill feed:60% corn. Daily gains were faster for diets 3 and 4 (1.26 and 1.30 kg/day, respectively) than for the broiler litter diet (0.89 kg/day). Daily dry matter intake (DMI) was less for steers consuming the rice mill feed-based diets.
In Exp. 2, 16 Angus x Charolais steers were fed the same four diets as in Exp. 1, but were measured for nutrient digestibility. Daily DMI was not different among the diets. Nutruient digestibilities also didn't vary among the diets.
In Exp. 3, 40 Continental-cross steers were fed one of four dietary treatments for 112 days. Diets consisted of 1) 47% broiler litter:53% soyhulls; 2) 70% rice mill feed:30% soyhulls; 3) 60% rice mill feed:40% soyhulls; and 4) 50% rice mill feed:50% soyhulls. Daily gains were less for the broiler litter diet than diet treatments 3 and 4, and steers fed the broiler litter diet consumed less DM than steers fed the varying rice mill diets.
In Exp. 4, 16 Angus x Charolais-cross steers were fed the same diet as Exp. 3 to determine nutrient digestibility. Daily DMI was less for the broiler litter diet. Digestibilities for DM, organic matter, and acid detergent fiber were equal among treatments.
Researchers concluded rice mill feed can be used as an adequate substitute for broiler litter to formulate low-cost diets for stocker calves. The rice mill diet can be blended with corn or soybean hulls to create an acceptable diet for growing beef calves.
(Stacey et al. 2004 J. Anim. Sci. 82:2193)