Reliabitliy of weaning weigth or age at weaning as a post growth predictor
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Seventy one Dorper lambs weaned at either 75 (n=39) or 105 (n=32) days of age (DOA) were placed on a growing diet and weighed every 7 days to determine body weight and growth rate. The objective of the project was to determine if weaning weight can be used to predict finishing weight. Average daily gain and percentage of body weight growth was calculated for each week as well as the full feeding period as a means of developing a growth curve to characterize the growth pattern of early weaning Dorper lambs. Lambs weaned at 105 DOA were born during the Fall 2016 and the growth period was during the Spring 2017 while the lambs weaned at 75 DOA were born during the Fall 2017 and the growth period was during the Spring 2018. Lambs weaned at 75 DOA averaged 30.4 kg at weaning while those weaned at 105 DOA were 32.1 kg. Following 42 days on feed, the 75 DOA lambs weighed 39.5 kg and the 105 DOA lambs weighed 40.0 kg. As a percentage of weaning weight the 105 DOA lambs were 142% of weaning weights while the 75 DOA lambs 131% of their weaning weights. This is a minimal difference in both percentage of weaning weights and actual weights, it appears that age at weaning might be as important or more than weaning weight in predicting post weaning growth. However, variation between two years suggests that more years of data are required to develop a reliable prediction equation.