PSVIII-18 Chemical composition of residual yolk in response to feeding broiler breeders hydroxychloride or organic sources of zinc, copper, and manganese from 42 to 63 wk of age

Abstract The objective was to investigate the effects of feeding broiler breeders (BB) hydroxychloride (HC) or organic (OR) sources of zinc (Zn), copper (Cu), and manganese (Mn) from 42 to 63 wk of age (woa) on chemical composition of residual yolk (RY). A total of 408 ♀ Ross 708 and 48 ♂ Yield Plus cockerels were placed in pens (17 ♀ and 2 ♂) housed in two rooms (12 pens/room) and allocated to one of two diets in a completely randomized block design (n = 12). The diets had similar nutrient specifications but differed in Zn, Cu, and Mn sources: 1) HO, a blend of 80% HC and 20% OR sources, and 2) OR, 100% OR sources ((Table 1 and 2). In total, 2,160 eggs (90 eggs from each pen replicate) were collected and labelled by BB pen at 46, 52 and 62 woa and incubated. For each incubation, embryos were euthanized at embryonic d (ED) 14 and 19 and at day of hatch (DOH) for the RY samples. On ED 14 and 19, six eggs per pen were individually weighed, and cracked open to dissect yolk sac and six hatchlings per pen (3 ♀ and 3 ♂) were individually weighed, and yolk sacs excised for DOH sampling. The RY weight (% of egg for ED or body weight for DOH), and dry matter and ash content were measured. The data at each sampling point was analyzed independently in a model with BB diet, age and associated interactions as fixed factors using PROC GLIMMIX procedures. There were no (P > 0.05) interactions between diet and BB age or main effects of trace mineral (TM) sources on any response criteria. The BB age effect was only observed for RY weight; in this context, the RY weight at ED 19 or DOH differed (P < 0.01) between BB age groups Table 3 and 4). Despite the lack of direct effects of TM sources on the measured criteria, these findings contribute to understanding the dynamics of RY composition in relation to BB age. Further research may explore additional factors influencing RY composition to optimize BB nutrition and subsequent offspring development.