LACK OF INTERACTIONS BETWEEN DIETARY LYSINE OR STRAIN CROSS AND PHOTOSCHEDULE FOR MALE BROILER PERFORMANCE AND CARCASS YIELD

The purpose of this study was to test interactions of dietary lysine o r strain crosses provided increased lysine with photoschedule on broil er performance and carcass quality. In Experiment 1, treatments were f actorially arranged as two lysine levels [control grower and finisher (NRC, 1984) or control grower and finisher plus .15% L-lysine HC1] and two photoschedules [23 h light (L):1 h dark (D) or 14L:10D]. All bird s received a control starter feed and dietary treatments were initiate d at 22 d of age. In Experiment 2, treatments were factorially arrange d as two strain crosses [Peterson x Arbor Acres (PAA) or Ross x Ross ( RR)] and two photoschedules (23L or 16L). All birds received standard starter and standard grower and finisher plus .15% L-lysine HC1. There were no lysine by photoschedule or strain cross by photoschedule inte ractions in this study. The high-lysine diet increased BW, improved fe ed efficiency, increased lean carcass weight and yield of breast meat, and decreased abdominal fat and yield of thighs. The PAA strain cross had better feed conversion, fewer Grade A carcasses, more back bruise s and breast blisters, greater yield of wings and drumsticks, and less yield of breast meat than RR. The 23L, had greater BW, better feed ef ficiency, fewer breast blisters, greater carcass weight (Experiment 1) , more abdominal fat (Experiment 2), lower yield of wings (Experiment 1), drumsticks, and thighs, and greater yield of breast meat than the treatments with shorter photoschedules. Increased dietary lysine did n ot compensate for decreased breast meat yield associated with 14L (Exp eriment 1).