Effects of L-Citrulline Supplementation on Rumen Microbiota and Reproductive Performance of Ewes

This study aimed to investigate the effects of L-Citrulline (L-Cit) supplementation on the rumen microbiota and reproductive performance of Turpan black ewes (each ewe was supplemented with 12 g of L-Cit daily). A total of 120 multiparous Turpan black ewes aged 1.5–2.5 years, with an average body weight of (52.35 ± 5.16) kg, were randomly divided into two groups: a control group (Con group) and an experimental group (L-Cit group), with 60 ewes in each group, for a 90-day supplementation trial. The results demonstrated that L-Cit supplementation regulated the rumen microbiota of ewes, increased the abundance of Clostridia vadin BB60 in the rumen, and stimulated the synthesis and release of reproductive hormones. Blood samples for hormone analysis and rumen fluid for microbiota profiling were collected from a subset of six ewes per group (n = 6). Compared with the Con group, L-Cit supplementation numerically increased oestrus rate (93.33% vs. 77.55%, p = 0.32) but did not significantly affect reproductive hormone concentrations (p > 0.05 for all). Conception rate was 100% in both groups among bred ewes. No significant changes in rumen microbiota alpha diversity or community structure were observed.