Impact of crumbled pelleted starter feed and alfalfa inclusion on feed intake, growth, and rumen microbiota in young lambs.

Pelleted feed has multiple advantages in animal production, but its hardness may limit the intake of young lambs whose teeth and digestive systems are not yet fully developed, especially when the feed contains alfalfa and is produced with a high compression ratio in small diameters. This study aimed to evaluate the effects of removing alfalfa from starter feed or post-pelleting crumbling on lamb performance. We hypothesized that crumbling pelleted feed could reduce hardness, thereby increasing intake and enhancing performance.A total of 118 healthy, 7-day-old Hu lambs (4.02 ± 0.94 kg) were allocated to three groups: (1) a pelleted starter with alfalfa (CON), (2) a non-alfalfa pelleted starter (NA), and (3) a crumbled starter with alfalfa (CA). Feed intake, growth performance, nutrient digestibility, and rumen microbial composition were measured.The CA group showed significantly reduced pellet hardness compared to the CON and NA groups (P < 0.05), while NA group had higher starch gelatinization (P < 0.05). CA notably increased feed intake, particularly after day 21 (P < 0.05), and achieved the highest overall intake, body weight (BW) and average daily gain (ADG) from days 7-49. The interaction between feed type and sex significantly influenced the digestibility of neutral detergent fiber (NDF) and acid detergent fiber (ADF). In male lambs, both NA and CA groups demonstrated significantly higher digestibility of NDF and ADF compared to the CON group (P < 0.05). Rumen microbiota diversity was influenced by feed composition more than pellet form, with alfalfa inclusion affecting a greater number of microbial genera. Crumbling increased the abundance of Methanobrevibacter (P < 0.05).These findings suggest that post-pelleting crumbling using a roller mill enhances feed intake and growth performance in young lambs, while feed composition plays a predominant role in shaping rumen microbial diversity.