Effects of maternal energetic efficiency on egg traits, chick traits, broiler growth, yield, and meat quality

This study assessed egg traits, chick traits, growth, yield, and meat quality characteristics of the offspring from broiler breeders classified by 2 measurements of energetic efficiency: residual feed intake (RFI), defined as the difference between observed and expected ME intake, and residual maintenance requirement (RME(m)), defined as the residual of the relationship between hen maintenance requirement and feed intake. A group of 72 pullets were placed in laying cages from 16 to 60 wk of age. Individual hen-based feed allocation was provided following a standard BW target. At 41wk, eggs from 8 d of production were collected and pedigree hatched. Chicks were assigned to 1 of 3 maternal RFI (RFI(mat)) categories: low, average, and high. A total of 366 chicks were placed in 36 floor pens, 6 per sex x RFI(mat) interaction, and raised to 38 d. At the end of the breeder experiment (60 wk), broilers were retrospectively assigned to a low or high maternal RME(m) (RME(mmat)) category. Low RFI(mat) broilers had greater 38-d BW than average and high RFI(mat) broilers. That was achieved through a greater BW gain and feed intake of low RFI(mat) broilers from 21 to 28 d. It was found that RFI(mat) had no effect on feed conversion, yield, or meat quality characteristics. Low RME(m) hens produced heavier eggs (62.3 g) and chicks (42.5 g) than high RME(m) hens (60.0 g; 41.0 g), but RME(mmat) did not affect broiler 38-d BW. High RME(mmat) broilers had greater breast yield (29.5%) and lower breast shear force (4.7 kg of force/g) than low RME(mmat) broilers (28.5%; 5.6 kg of force/g). The low RFI(mat) x high RME(mmat) broilers had the greatest growth to 38 d. It was found that RFI(mat) was inversely related to broiler growth, particularly when RME(mmat) was high. Although low maintenance requirements may be desirable for egg and chick production, hens with a high maintenance requirement produced broilers with greater breast yield and tenderness. Minimizing maintenance requirements may not be compatible with maximizing broiler performance and meat yield.