Recent studies have shown that in pre-weaning ruminants, the addition of alfalfa hay is beneficial for growth and rumen development. However, the effect of alfalfa supplementation timing on the growth of pre-weaning lambs remains still unclear. This study aims to explore the growth performance, blood parameters, rumen epithelial microbiota, and rumen tissue gene expression in response to alfalfa supplementation starting from either 14 d or 42 d of age in pre-weaning lambs. Our results indicate that alfalfa supplementation at 14 d of age could increase the average daily gain, starter intake, and total dry matter intake, but did not persist over the long term. When compared with the consumption of alfalfa starting at 42 d of age, starting to consume alfalfa at 14 d of age could improve immune response and promote rumen tissue cells proliferation. Furthermore, the supplementation of alfalfa, starting at 14 d of age, not only increased the abundance of Megasphaera, but also affected dynamical changes in the rumen epithelial microbiota. Additionally, our findings suggest that the rumen undergoes significant physiological challenges during the transition from a liquid diet to a solid diet.

Read the full article in the Journal of Animal Science.