The Economic Effects of Early-Life Nutritional Constraints in Crossbred Cattle Bred on the NSW North Coast

Different patterns of nutrition during pregnancy and lactation can influence cow productivity and the performance of their offspring. An experiment was conducted on the North Coast of NSW whereby “low” and “high” pasture nutritional systems were imposed on a herd of Hereford cows during pregnancy, and then again from birth to weaning, with a crossover design also imposed to select offspring with extremes of growth to birth and/or weaning. Thus, four growth groups resulted – low-low, low-high, high-low, and high-high. Piedmontese and Wagyu bulls were used. After weaning, these offspring were grown out on the NSW Northern Tablelands and then finished to heavy market weights in a feedlot. The results of the experiment indicated that restricted early-life growth resulting in differences in weight of calves at weaning persisted until slaughter at 30 months of age. Animals that were smaller at weaning remained smaller at slaughter. Some compensation occurred following restriction of growth during lactation, but not following restriction of growth during pregnancy. However, neither carcass quality nor eating quality of the beef was adversely affected by growth restriction during early-life. An economic analysis of these data was done using the Beef-N-Omics decision support package. Two methods were used. The main results showed that for the representative cattle enterprise modelled, total gross margins ranged from $45,500 for the low-low system to $52,600 for the high-low system. Gross margin per hectare ranged from $114 for the low-low system to $132 for the high-low system, while gross margin per breeding cow ranged from $303 for the low-low system to $387 for the high-high system. In all cases, the gross margin for those groups with foetal growth based on a higher level of nutrition exceeded their peers on a lower level of nutrition. Therefore, it is more profitable for cows and calves to have access to a high standard of nutrition during pregnancy and up to weaning than for them to have access only to a poor standard of nutrition during this time period