Effect of maternal dietary energy and protein on live performance and yield dynamics of broiler progeny from young breeders.

The objective of this research was to evaluate effects of female broiler breeder dietary ME and CP during rearing and dietary ME during early lay on broiler offspring performance and carcass yield dynamics. A factorial arrangement of treatments, with 2 ME levels, and 2 balanced protein levels from 3 to 24 wk, followed by 2 ME levels in the lay diets, and in the broilers, 2 sexes. A total of 1,635 broilers were housed in 32 pens, with 8 replicate pens according to maternal laying diet and sex. Maternal pullet diets were nested within pen (n = 9 to 14, depending on hatch rate). The broilers originated from 384 Ross 708 hens, which had been fed diets containing high (2,736 kcal/kg, HEREAR) or low ME (2,528 kcal/kg, LEREAR) combined with either high (15.3%, HPREAR) or low balanced protein (13.7% CP, LPREAR). Equal numbers of hens from each pullet treatment were then fed either a high (2,900 kcal/kg, HELAY) or low ME diet (2,800 kcal/kg, LELAY) containing 15% CP. Broilers were hatched from eggs collected at 28 wk of age, and fed identical diets. Broilers were individually weighed weekly. Serial dissections were conducted to evaluate yield breast muscle and abdominal fatpad dynamics. At 39 d, 180 broilers were processed to measure carcass yield. Female progeny of hens with the lowest CP intake during rearing (HEREAR × LPREAR) were lighter from 22 to 36 d of age than female offspring from hens that consumed more CP as pullets. We predicted the heaviest female progeny would result from an ME:CP ratio of 18.25 kcal/g in maternal pullet diets (P = 0.0063). Broiler breast yield increased when maternal EM:CP ratio increased after switching from pullet to laying diets. Hens fed HEREAR were fatter and had fatter progeny than LEREAR. Maternal diet, even during the pullet phase, influenced progeny growth and yield.