Animal Industry Report

Extension Number

ASL R3020



Summary and Implications

Body weight, body composition, feed intake (FI) and carcass traits of 1221 crossbred Large White × Landrace gilts housed in groups from 100 d of age until slaughter (approximately 260 d of age) and randomly allotted to six corn-soybean diets formulated to provided two standardized ileal digestible lysine levels [100% (high, HL) and 85% (low, LL)] and three metabolizable energy levels [ME, 90% (low, LME), 100% (medium, MME), 110% (high, HME) were evaluated. There were no differences between lysine or ME levels for growth and body composition, except for back fat, which was slightly greater for gilts fed a HME diet (~ 2 mm). Gilts fed HME diets had a lower FI but a greater ME intake compared with gilts fed LME. Additionally, gilts fed the HME diet had consumed less feed and less grams of lysine per each kg of body weight gain. However, there was no difference in the ME required per kg of body weight gain among diets. Carcasses from gilts fed the HME diet were 3.3 kg and 2.5 kg heavier than those from gilts fed the LME or MME diets, respectively. Despite significant differences in the lysine:ME ratio in the diets no changes in growth or body composition traits occurred, likely due to compensatory changes in FI in response to dietary ME content. Carcass weight differences at slaughter were likely related to organ size and organ weight, which could have been affected by FI. Further research is necessary to identify the optimal lysine-to-energy ratio to manipulate growth and body composition in replacement gilts fed ad libitum.

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