In Poultry Science, first-named author, R.D. Ekmay of Cornell University, and co-authors from DSM, Novus International and the University of Arkansas report three experiments investigating the amino acid requirements of broiler breeders at peak production for egg mass, body weight and fertility.

Two trials were conducted to determine the amino acid and protein requirements of broiler breeders at peak production.

In trial 1, 32-week-old Cobb 500 broiler breeders with similar bodyweight were selected to determine the digestible amino acid requirement for daily product output (g of egg mass + g of bodyweight gain per bird and day) and feed conversion (g of feed per g of product) for methionine (Met), phenylalanine (Phe), arginine (Arg), isoleucine (Ile), lysine (Lys) and crude protein (CP) in a 42-day production study.

In trial 2, 30-week-old Cobb 500 broiler breeders were selected to determine the digestible requirement for methionine, lysine, isoleucine, arginine, cystine (Cys), valine (Val), tryptophan (Trp) and threonine (Thr) in a 70-day production study. Breeders were given a corn-soy basal diet plus crystalline amino acids with eight graded levels of amino acids (10 birds per level), representing 40 to 130 per cent of the highest suggested requirements reported in the literature. All other amino acids were maintained at 100 per cent of their suggested requirement level. All breeders were inseminated weekly and fertility was determined.

A third trial consisted of 41-week-old colostomised hens randomly assigned to one of two diets differing only in the amount of isoleucine. Urine was collected after a six-week feeding period.

The average digestible requirements per breeder per day for both product and feed/product ratio from trials 1 and 2 for methionine, cystine, total sulphur amino acids (TSAA), phenylalanine, phenylalanine + tyrosine (Tyr), tryptophan, arginine, isoleucine, lysine, valine, threonine and crude protein were 424, 477, 901, 689, 997, 252, 1,026, 830, 916, 799, 613mg per day and and 20.0g per day, respectively.

The ideal profile for digestible methionine, cystine, TSAA, phenylalanine, phenylalanine + tyrosine, tryptophan, arginine, isoleucine, lysine, valine and threonine was 46, 52, 98, 76, 108, 28, 112.0, 91, 100.0, 87, and 67 per cent, respectively.

A significant decrease in fertility was noted with increasing levels of isoleucine and lysine. Urine pH was significantly more alkaline in hens fed the higher level of isoleucine.

It is suggested that adequate dietary lysine and isoleucine should be provided for maximum hatching egg production but an excess may affect fertility, Ekmay and co-authors concluded.

Reference

^{Ekmay R.D., M. De Beer, S.J. Mei, M. Manangi and C. N. Coon. 2013. Amino acid requirements of broiler breeders at peak production for egg mass, body weight, and fertility. Poult. Sci. 92(4):992-1006. doi: 10.3382/ps.2012-02554}

May 2013