58 Effects of gestational nutrition in an earlier pregnancy on growth of subsequent offspring in grazing beef cattle

Abstract Abstract: Introduction Human health effects due to birth order have been extensively studied. This topic is less researched in livestock, likely due to pronounced confounding of birth order with age of dam in a k-strategist managed to conceive “early and often”. Emerging evidence indicates a need to better understand longitudinal effects of gestational nutrition on health and well-being of future progeny in livestock. Objective To determine the effects of beef cow stocking rate (SR; a proxy for cow nutrition) at three different production cycle periods on performance measures in offspring. Methods 1,900 records from calves born over a 30-year period to Bos taurus x B. indicus cross cows at three SR (high, moderate, low) and periods (previous gestation, current gestation, current suckling) were analyzed. Calf weight and performance data were collected during the suckling period, the feedlot period, and from carcasses. Results Nutrition during gestation and suckling affected calves as expected; i.e. measures from high SR calves were generally lower (P < 0.05) than those from moderate and low. High SR during the pregnancy immediately previous to that of a given calf had no effect (P > 0.1) on calf birth weight but generally depressed measures of feedlot/carcass performance compared to moderate and low (P < 0.05). Specifically, hot carcass weight (kg) was 376 ± 2.5, 390 ± 1.3, and 386 ± 2.9, for high, moderate and low SR, respectively. Conclusion Intrauterine conditions of an earlier pregnancy affected outcomes for future offspring at the point of harvest. (Funded by Texas Cattle Feeders Association)