Effect of Changes in Weaning Age on Carcass Traits in Forage Finished Beef Cattle
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An increase in percent intramuscular fat (%IMF) and average daily gain (ADG) are advantageous to the profitability and consumer palatability of forage finished beef. The effects of weaning age in beef cattle fed an all forage diet on measure of weight gain and carcass quality were analyzed over two years of calf data. Measures of gain included average daily gain, weight per day of age (WDA), and weight at the conclusion of trial two weaning (CW2). Measures of carcass quality included percent intramuscular fat, Longissimus muscle area (REA), rib fat (BF), finished live-weight (FW), rump fat (RF) at the conclusion of trial two weaning, empty body fat (EBF) and Longissimus muscle area as a function of finished weight (REA/FW). Angus x Simmental beef calves (N=50 over two years) were weaned at two distinct ages. In both trials, calves were weaned using a calf-weaner, a plastic removable nose ring used for low stress weaning. In trial one calves were weaned at the time normally practiced, approximately 157 (+13) days of age in 2004 and 182.7 (+ 9.7) days of age in 2005. In trial two the time of weaning was delayed to 338.5 (+ 13.6) days of age in 2004 and 266.1 (+ 8.4) days of age in 2005. Following weaning in both trails, calves were fed an all forage diet. For calves born in 2004, carcass data for both weaning groups was gathered by ultrasound at 597(+ 13.6) days of age; in 2005, calves from both trails were analyzed by ultrasound at approximately 554(+ 8.9) days of age. The calves in which weaning was delayed showed numerically higher values for percent intramuscular fat, rib eye area, rump fat, back fat, finished weight, weight per day of age, empty body fat (percent), and rib eye area as a function of finished weight. These differences however were generally not statistically significant using the general linear model in SAS (1998), and analyzing least square means using The Waller-Duncan K-ratio t test. There was a statistically significant difference in WDA and CW2 for 2005 born calves. The results of this research potentially show a relationship between delaying weaning and an increase in the carcass quality of forage finished beef. As farmers producing forage finished beef seek to compete for market share in a market primarily dominated by grain finished, highly marbled, younger carcasses, a delay in weaning age may produce carcasses which are more highly competitive in the current market and capable of better suiting consumer preferences.
dissertation or thesis