The effects of dietary protein levels during rearing and dietary energy levels during lay on body composition and reproduction in broiler breeder females have been investigated by researchers at Wageningen UR and Wageningen University in the Netherlands. Their experiment is published in the new issue of Poultry Science.

Lead author, Rick van Emous and his colleague conducted the experiment with a 2×3×2 factorial arrangement to determine the effects of two dietary protein levels (high = CPh and low = CPl) during rearing, three dietary energy levels (3,000, MEh1; 2,800, MEs1; and 2,600, MEl1, kcal per kg AMEn, respectively) during the first phase of lay, and two dietary energy levels (2,800, MEs2; and 3,000, MEh2, kcal per kg AMEn, respectively) during the second phase of lay on body composition and reproduction in broiler breeders.

They found no meaningful interactions for energy and protein treatments within the different phases of the study and so their paper focuses on the main effects.

Pullets fed the CPl diet had a 12.8 per cent higher feed intake, 14 per cent lower breast muscle, and 97 per cent higher abdominal fat pad portion at 22 weeks age.

The increased abdominal fat pad and decreased breast muscle of the CPl compared to the CPh birds increased hatchability during the first phase of lay, due to a decreased embryonic mortality between days 10 to 21 of incubation, and increased egg production during the second phase of lay.

Feeding birds the MEh1 and MEl1 diets slightly decreased egg production compared to the MEs1 birds.

Birds fed the MEh1 diet showed a higher mortality compared to the birds fed the MEs1 and MEl1 diets.

Feeding birds the MEh2 diet did not affect egg production, increased hatchability of fertile eggs, decreased embryonic mortality between days 3 to 21 of incubation, and increased the number of first-grade chicks.

A low-protein diet during rearing changed body composition with positive effects on incubation traits during the first phase of lay and improved egg production during the second phase of lay in broiler breeders, concluded Dr van Emous and co-authors.

They added that a high-energy or low-energy diet compared to a standard diet during the first phase of lay slightly decreased total and settable egg numbers, while a high-energy diet during the second phase of lay increased hatchability and the number of saleable chicks.

Reference

van Emous R.A., R.P. Kwakkel, M.M. van Krimpen and W.H. Hendriks. 2015. Effects of dietary protein levels during rearing and dietary energy levels during lay on body composition and reproduction in broiler breeder females. Poultry Science. 94:1030-1042.
doi: 10.3382/ps/pev079

April 2015