Research on the influencing factors of ovum pick-up efficiency in Holstein heifers

Zhang Yisong; Wang Ge; Zhang Yi; Guo Jiyuan; Ji Shukun; Wang Chaoran; Ge Changsheng; Zhu Kai

doi:10.20154/j.cnki.issn1672-9692.2025.12.008

Abstract：This study aimed to investigate the effects of different ages and dietary β-carotene supplementation on the ovum pick-up(OPU)efficiency in young Holstein heifers.The experiment was divided into two parts:First,600 heifers were randomly assigned to six groups based on age and underwent hormonal treatment and OPU using the same protocol.Subsequently,230 healthy heifers of comparable age and body condition were randomly divided into a control group(fed a basal diet)and a treatment group(supplemented with β-carotene).They received the same hormonal treatment,and OPU was performed when the donor heifers reached 9 months of age.The results showed that the average number of cumulus-oocyte complexes(COCs)collected per donor was highest in 9-month-old heifers,reaching 21.93.The distribution of COCs across different quality grades varied among heifers of different ages.Adding β-carotene to the diet increased the quantity of COCs obtained by donor cattle and significantly improved the quality of oocytes:The proportion of grade 1 COCs in the experimental group was significantly higher than that in the control group(P<0.05),and the proportion of grade 4 COCs was significantly lower than that in the control group(P<0.05).Studies have shown that there are significant differences in the efficiency of live oocyte retrieval among young Holstein dairy cows of different ages,which provides a basis for determining the optimal age for live oocyte retrieval among young donor cows.The addition of β-carotene to the diet can affect the quantity and quality of COCs obtained during live oocyte retrieval,indicating that it has a regulatory effect on the reproductive physiology of dairy cows and can be used as an effective nutritional strategy to improve oocyte retrieval efficiency and in vitro embryo production.