Effects of maternal rumen-protected methionine supplementation on ewe colostrum composition, lamb growth performance, rumen development and microbiome

Maternal nutritional status during late gestation and lactation significantly influences the development and physiological metabolism of the offspring. Supplemental rumen-protected methionine (RPM) has the potential to enhance the development and growth of both ewes and their lambs. This study was performed to investigate the effects of maternal RPM supplementation on growth performance, blood metabolites, rumen morphology and fermentation parameters, as well as microbial composition of offspring lambs. Twenty Hu ewes were subjected to simultaneous estrus by inserting sponge containing progesterone into the vagina. At fifty-five days before the expected parturition date, the pregnant ewes (2-3 years of age, 53.7 +/- 2.77 kg of weight) were randomly assigned to two groups: 1) Ewes were fed a basal diet with no RPM supplementation (CON, n = 7), 2) Basal diet supplementation with 0.25 % DM of RPM (MET, n = 5). After lambing, the lambs were fed milk from their mothers and fed starter from d 14 to d 42 of life. The results indicated that MET ewes had higher colostrum fat content than CON ewes. Birth weight (BW), average daily gain (ADG), and weaning weight of lambs showed increase in response to RPM added in the maternal diets (P < 0.05). Similarly, concentrations of insulin-like growth factor-1 (IGF-1) was elevated with maternal RPM addition (P < 0.05). Moreover, GSH-PX showed an increasing trend, while AST showed a decreasing trend in MET lambs. The length, width and total epithelia thickness of rumen papillae were higher in the MET compared with the CON (P < 0.05). In term of proliferative genes expression, MET lambs had greater TJP1 and PCNA expression than in CON (P < 0.05). The ruminal total volatile fatty acid was not affected, whereas iso-butyrate and iso-valeric levels increased with maternal RPM addition (P < 0.05). Moreover, the 16S rRNA sequencing profile showed that relative abundance of Actinobacteria was decreased while Prevotella-1 was increased with RPM supplementation (P < 0.05). These results indicated that maternal RPM supplementation promoted growth performance of the lambs by improving colostrum composition of ewes, and serum parameters, rumen fermentation, and rumen micro- biota of lambs.