Nutrition II

S OF PAPERS 229 72 Effects of feeding various digestible lysine intake levels by Cobb 500 broiler breeder hens on reproductive performance. L. Mejia*SC, C. D. McDaniel, and A. Corzo, Mississippi State University, Mississippi State. A study was conducted to examine the reproductive parameters of Cobb 500 broiler breeder hens fed different daily consumption levels of dig lysine (mg/hen/day) on the reproductive parameters of Cobb 500 broiler breeder hens. A total of 240 Cobb 500 broiler breeder pullets and 40 cockerels, 20 wk of age, were obtained from a commercial blackout rearing house and placed in individual cages. A pre-breeder diet (CP 16%, Ca 1.50%, dig lysine 0.92%) was fed from 21 to 24 wk of age, and a breeder diet (CP 16%, Ca 3.0%, dig lysine 0.65%) was fed from 25 to 34 wk of age, respectively. Experimental diets were fed from 35 to 45 wks of age. Treatment 1 and 2 diets were formulated with commercially available ingredients and resulted in daily dig lysine intakes of 1,200 (IDL) and 1,010 mg/hen/day (ID), respectively. Treatments 3 and 4 were semi-purified diets and used L-glutamic acid to maintain isonitrogenous conditions, with dig lysine levels 1,010 (SPL) and 600 mg/hen/day (SP). Hens fed the SPL and SP diets had lower hen-day egg production than hens fed the ID diet, with hens receiving the IDL diet yielding intermediate values. Hens fed the SP diet had the lowest (P < 0.05) egg weight but no differences were observed among dietary treatments for egg specific gravity. Fertility and hatch of set were lowest (P < 0.05) for hens fed the SPL dietary treatment. No differences were observed for early and middle dead, contaminated or pipped eggs. Late dead was observed to be higher (P < 0.05) in hens fed the SPL diet. A decrease in the daily intake of dig lysine from 1,010 to 600 mg/hen/day improved broiler breeder reproductive performance when hens were fed semi-purified diets, but the same did not occur when reducing dig lysine intake from 1,200 to 1,010 when using commercial-type diets.