Effect of Replacing Alfalfa Hay with Common Vetch Hay in Sheep Diets on Growth Performance, Rumen Fermentation and Rumen Microbiota

The aim of this study was to determine whether the inclusion of 40% of common vetch (CV) hay as a feed ingredient in place of alfalfa hay (AH) would improve performance and ruminal fermentation and microbiota in fattening lambs. Twenty lambs were equally divided into two groups: control group (fed 40% AH with 20% rice straw) and CV group (fed 40% CV hay with 20% rice straw). Concerning hay quality, CV hay had greater in vitro digestibility of dry matter and neutral detergent fiber (p < 0.05) than AH. Lambs fed the CV diet had a higher average daily gain (ADG) and efficiency of feed and economy than lambs fed the control group. The NH3-N content and estimated methane produced per unit of ADG of the CV diet group were significantly lower (p < 0.05) than control group. Multiple differential microbial genera were identified, with Prevotella being the most dominant genus and a tendency towards higher (p = 0.095) in lambs offered CV diet. The higher Ruminococcus abundance (p < 0.05) was found in animals of the CV group compared to the control group. In summary, CV can be incorporated into lamb diets as a low-cost forage alternative to AH to improve feed efficiency and animal performance and to reduce methane produced per unit of ADG.