Characterization of serum metabolome changes during the 5 weeks prior to breeding in female goat kids

This prospective study aims to analyze the serum metabolome of female goat kids just before the first breeding in order to characterize the changes in metabolites during sexual maturation. A better knowledge of these changes could help optimizing the time for first breeding and improving the fertilization rates at first insemination. Weekly blood sampling was performed on twenty 6- to 7-month-old female goats from Alpine breed born in February during the 5 weeks preceding their first contact with bucks in September. Progesterone assays and metabolome analysis using 1H Nuclear Magnetic Resonance Spectroscopy were performed on the serum samples. No spontaneous ovulatory cycle was observed before breeding based on progesterone assays. All female goats had reached the pubertal stage of maturity at breeding since all got pregnant. Metabolome analysis allowed the identification of 109 spectral bins in sera. When the metabolic profiles were compared between the 5 weeks preceding the first contact with bucks, 6 metabolites were highlighted that could differentiate between week 5 and week 1, 2 and 3: glucose, citrate, creatinine, 3-hydroxy-isobutyrate and two unidentified bins. Citrate and 3hydroxy-isobutyrate are of particular interest because their level significantly varied during sexual maturation, with a significant decrease of 3-hydroxy-isobutyrate at week 5 and a significant increase of citrate at week 4 and 5. However, the lack of variability in the fertility results did not allow us to conclude on a potential link between these metabolomics profile and reproduction performances. Further studies are necessary to ascertain the reliability of these metabolites as biomarkers of sexual precocity.

Automated summary

This study analyzed the serum metabolome of female goat kids before sexual maturation, identifying significant changes in citrate and 3-hydroxy-isobutyrate levels during maturation. However, further research is needed to confirm the potential link between metabolites and reproductive performance.