Effects of massive ovulation on oxidation state and function of the ovaries in laying hens

Abstract

Modern laying hens show fast reduction in egg production rate after 60 weeks of age, which is associated with the decline inovarian function. The aim of this study was to examine the influence of massive ovulation on the oxidation state and ovarian functionin hens. In total, 48 Jing Hong hens aged 17 weeks were randomly divided into high ovulation (HO) and low ovulation (LO) groups.The LO hens were exposed to 6 h of light per day (6 L:18 D) up to 32 weeks to delay the initiation of egg production and then wereswitched to 16 L:8 D. The HO hens were reared at 16 L:8 D from 19 weeks. The treatment effects were analyzed by the independentsamples t-test using SAS 9.0 software (SAS Institute, Cary, NC, USA). At 36 weeks, there were no significant differences in body weight(P > 0.05) between the two groups and the egg production rate of both groups reached 98%; however, the cumulative egg number in theHO group was much higher than that in the LO group (71.3 versus 18.5, respectively; P < 0.001). The following parameters decreasedin the HO hens compared with the LO hens: the number of small yellow follicles (SYFs, P < 0.001) and large white follicles (LWFs, P