Objective: Pelleted feed offers several advantages in animal production, yet its hardness can limit intake for young lambs with underdeveloped teeth and digestive systems, particularly when alfalfa inclusion and high compression ratios for small-diameter pellets are involved. This study aimed to evaluate the effects of removing alfalfa from starter feed or post-pelleting crumbling on feed intake, growth, nutrient digestibility, rumen fermentation, and microbial composition in lambs. We hypothesized that crumbling pelleted feed could reduce hardness, thereby increasing intake and enhancing performance.Methods: A total of 117 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).Results: The CA group exhibited significantly lower pellet hardness compared to CON and NA (P < 0.05), while NA 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 and average daily gain (ADG) from days 7–49. Feed type and feed type-sex interactions significantly affected NDF and ADF digestibility, with NA and CA outperforming CON (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).Conclusion: 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.

Understanding the effects of weaning on the changes of digestive function could help to design efficient intervention strategies for promoting the development of the lamb during the early stages of life. In this study, 24 lambs were divided into two groups (control group, lambs were not weaned; and weaning group, lambs were weaned at 21 days of age). The growth, nutrient digestion, gastrointestinal enzyme activity, plasma biochemical indicators, and intestinal microbiota at 7–49 days were determined, as well as the impact of early weaning. The nutrient digestion changed rapidly with age, especially at 14–28 days (p < 0.05). Weaning reduced the dry matter (DM), crude protein (CP), and ether extract (EE) intake and digestion, but increased the starch, neutral detergent fiber (NDF), and acid detergent fiber (ADF) intake and digestion (p < 0.05). Weaning did not affect the overall jejunal microbiota (p > 0.05), but affected the relative abundance of certain bacteria taxa (p < 0.05). Lactic acid-producing bacteria, such as Olsenella, Bacillus, Sharpea, and Bifidobacterium are closely related to CP or EE digestion and growth performance (p < 0.05). In summary, we delineated the pattern of nutrient digestion and intestinal microbiota development in young lambs, and the impact of early weaning.

Early mammal gut microorganism colonization affects host health, the feed conversion rate, and production performance. Herein, we explored how fecal microbiota develops and the interactions between microorganisms and nutrients. The lambs were separated from ewes at 7 days old, artificial feeding with milk replacer completely replaced lactation, and the starter diet was added. At 21 days old, the lambs were fed with complete starter and milk replacer was stopped. At day 7, 21, 35, and 49 after birth, fecal samples were collected. Then 16S rRNA gene sequencing in the fecal samples revealed that the alpha diversity increased significantly with age. Principal coordinates analysis showed clear clustering by age (p < 0.05). At the genus level, the relative abundance of 8 genera declined, 12 genera increased (p < 0.1), and 4 genera changed dramatically with age (p < 0.05). The apparent digestibility of dry matter, protein, fat, neutral detergent fiber, and acid detergent fiber significantly decreased by 21.77%, 23.15%, 23.62%, 19.38%, and 45.24%, respectively, from 7 to 35 days of age (p < 0.05), but not thereafter (p > 0.05). Fecal nutrient contents affected the abundance of bacterial genera (p < 0.05). Enterobacteriaceae_unclassified, Clostridium XlVb, Bifidobacterium, and other genera had no relationship with the fecal nutrient content; however, they were closely related to nutrient intake and digestibility, possibly promoting nutrient digestion. Our results suggested that nutrient digestion of young lambs changed rapidly, which was closely related to intestinal microbial colonization.

Despite the known impacts of weaning on animal health, the underlying molecular mechanisms remain unclear, particularly how psychological and nutritional stress differentially affect gut health and immune function over time. This study hypothesized that early weaning exerts distinct short- and long-term effects on lamb stress physiology, immunity, and gut health, mediated by specific molecular pathways. Twelve pairs of full-sibling male Hu sheep lambs were assigned to control (CON) or early-weaned (EW) groups. Plasma stress/immune markers were dynamically monitored, and intestinal morphology, antioxidant capacity, apoptosis, and transcriptomic profiles were analyzed at 5 and 28 days post-weaning. Early weaning triggered transient psychological stress, elevating hypothalamic–pituitary–adrenal (HPA) axis hormones (cortisol, catecholamines) and inflammatory cytokines (TNF-α) within 1 day (p < 0.05); however, stress responses were transient and recovered by 7 days post-weaning. Sustained intestinal remodeling was observed in EW lambs, featuring reduced ileal villus height, increased crypt depth (p < 0.05), and oxidative damage (MDA levels doubled vs. CON; p < 0.01). Compensatory epithelial adaptation included increased crypt depth but paradoxically reduced villus tip apoptosis. The transcriptome analysis revealed significant changes in gene expression related to immune function, fat digestion, and metabolism. Key DEGs included APOA4, linked to lipid transport adaptation; NOS2, associated with nitric oxide-mediated immune–metabolic crosstalk; and mitochondrial gene COX1, reflecting energy metabolism dysregulation. Protein–protein interaction analysis revealed NOS2 as a hub gene interacting with IDO1 and CXCL11, connecting oxidative stress to immune cell recruitment. Early weaning exerts minimal lasting psychological stress but drives persistent gut dysfunction through transcriptome-mediated changes in metabolic and immune pathways, highlighting key genes such as APOA4, NOS2, and COX1 as potential regulators of these effects.

Despite the known impacts of weaning on animal health, the underlying molecular mechanisms remain unclear, particularly how psychological and nutritional stress differentially affect gut health and immune function over time. This study hypothesized that early weaning exerts distinct short- and long-term effects on lamb stress physiology, immunity, and gut health, mediated by specific molecular pathways. Methods: Twelve pairs of full-sibling male Hu sheep lambs were assigned to control (CON) or early-weaned (EW) groups. Plasma stress/immune markers were dynamically monitored, and intestinal morphology, antioxidant capacity, apoptosis, and transcriptomic profiles were analyzed at 5- and 28-days post-weaning. Results: Early weaning triggered transient psychological stress, elevating hypothalamic-pituitary-adrenal (HPA) axis hormones (cortisol, catecholamines) and inflammatory cytokines (TNF-α) within 1 day (P < 0.05); however, stress responses were transient and recovered by day 7. Sustained intestinal remodeling was observed in EW lambs, featuring reduced ileal villus height, increased crypt depth (P < 0.05), and oxidative damage (MDA levels doubled vs. CON; P < 0.01). Compensatory epithelial adaptation included increased crypt depth but paradoxically reduced villus tip apoptosis (decreased TUNEL+ cells), suggesting stress-driven suppression of programmed cell death to preserve epithelial integrity. Transcriptome analysis revealed significant changes in gene expression related to immune function, fat digestion, and metabolism. Key DEGs included APOA4, linked to lipid transport adaptation; NOS2, associated with nitric oxide-mediated immune-metabolic crosstalk; and mitochondrial gene COX1, reflecting energy metabolism dysregulation. Protein-protein interaction analysis revealed NOS2 as a hub gene interacting with IDO1 and CXCL11, connecting oxidative stress to immune cell recruitment. Conclusion: These findings underscore the intricate interplay between metabolic stress, immune function, and gut health during early weaning. Early weaning exerts minimal lasting psychological stress but drives persistent gut dysfunction through nutritional-metabolic reprogramming. This study elucidates the molecular mechanisms driving these changes. Future studies should address strategies to mitigate oxidative stress and optimize lipid utilization during the weaning transition.

Objective: Pelleted feed has multiple advantages in animal production, but its hardness may limit the intake of young lambs with underdeveloped teeth and digestive systems, 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.Methods: 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.Results: The CA group demonstrated significantly reduced pellet hardness than 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 and average daily gain from days 7–49. The interaction between feed type and sex had significant impacton 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).Conclusion: 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.