Submitted to: Poultry Science
Publication Type: Abstract Only
Publication Acceptance Date: October 21, 2003
Publication Date: January 26, 2004
Citation: Buhr, R.J., Northcutt, J.K. 2004. The calculation of eviscerated carcass weight as a percentage of initial weight prior to initiation of feed withdrawl for broilers. [abstract] Southern Poultry Science Society and Southern Conference on Avian Diseases. Paper No.17.
By definition feed withdrawal periods either 'precede' or are 'subsequent' to attaining a specific age or time of day. Feed withdrawal studies for broilers have almost exclusively used feed withdrawal periods that have preceded the processing time of the full fed controls. To accurately compare carcass yield, the feed withdrawal period must be subsequent to attaining the same age or time on feed as the full fed control broilers. Our current experiments with 7 wk old broilers evaluated the determination of carcass yield as influenced by both preceding and subsequent feed withdrawal periods of 6, 12, 18, or 24 h. Comparisons were made to initial live weight (prior to initiation of feed withdrawal, 0 h) for eviscerated carcass weight percentage. Carcass weight percentages increased for broilers that remained on feed by 2.2% after 6 h, 3.4% after 12 h, 3.9% after 18 h, and 4.4% after 24 h when compared to the full fed controls processed at 0 h. Broilers subjected to a subsequent feed withdrawal period of 6 h also had increased carcass weight percentages by 0.8% and after a 12 h period a minimal increase of 0.3%. After an 18 h subsequent feed withdrawal period eviscerated carcass weight percentages had declined by 1%, and declined by 0.8% after a 24 h of feed withdrawal period. In contrast, if comparisons are made to those broilers that remained on feed for an additional 24 h (preceding feed withdrawal), there was a difference in eviscerated carcass weight of 3.4% after 6 h, 4.0% after 12 h, 5.2% after 18 h, and 5.0% after 24 h feed withdrawal. Comparisons to the full fed control broilers after an additional 24 h on feed (preceded feed withdrawal periods) resulted in calculation errors of 4.2% above the values from comparisons to the full fed controls processed at the time feed withdrawal was initiated 0 h (subsequent feed withdrawal periods).