Effects of breeder hen age and dietary fat on embryonic and neonatal broiler serum lipids and glucose.

In two experiments, the effects of dietary fat and breeder hen age on relative yolk sac weight (RYSW) and total serum cholesterol (CHOL), high (HDLC) and low (LDLC) density lipoprotein cholesterol, triglycerides (TRI), and glucose (GLU) were monitored in broiler embryos and chicks. In Experiment 1, embryos at 18 d of incubation and chicks at hatch were sampled from eggs laid by breeder hens at 26 (young), 36, and 48 wk of age. No dietary effects were noted in either experiment; however, chicks from young hens exhibited elevated serum CHOL, HDLC, LDLC, and lower GLU when compared with chicks from hens at either 36 or 48 wk of age. Additionally, embryos from young breeders displayed a lower RYSW at 18 d of incubation. Conversely, by hatch there was no difference in RYSW among offspring from different aged hens. In Experiment 2, newly hatched chicks were sampled from breeder hens at 36, 51, and 64 wk of age. Dietary effects were also not evident in this experiment; however, chicks from 51-wk-old breeders displayed the highest and lowest serum HDLC and TRI, respectively, compared to the other two age groups, whereas chicks from either 51- or 64-wk-old breeders exhibited higher levels of CHOL than those at 36 wk. Chicks from 64-wk-old breeders displayed an increase in LDLC when compared with the other two ages. These data suggest that serum concentrations of lipids and GLU, and RYSW in 18 d embryos and newly hatched chicks are influenced by hen age and not by added dietary fat.