Alfalfa Intervention Alters Rumen Microbial Community Development in Hu Lambs During Early Life

The pre-weaning period is crucial for rumen developmental plasticity, which can have a long-term impact on animal performance. Understanding the rumen microbiota during early life is important to elucidate its potential role in rumen development. In this study, the rumen microbiota of 10-day-old Hu lambs fed either milk replacer (B-10), milk replacer and starter (STA) or milk replacer and starter supplemented with alfalfa (S-ALF) in the pre- (d17, 24, and 38) and post-weaning periods (d45 and 66) were assessed to characterize rumen microbial colonization during early life and its response to fiber intervention. In the rumens of B-10 lambs, 498 operational taxonomic units belonging to 33 predominant genera were observed, and the top six predicted functions included “Membrane transport,” “carbohydrate metabolism,” “amino acid metabolism,” “replication and repair,” “translation,” and “energy metabolism.” Prevotella, Succinivibrio, Bifidobacterium, and Butyrivibrio abundances were increased at d38 for both STA and S-ALF groups compared to the B-10 group, whereas fibrolytic bacteria of the taxa Lachnospiraceae and Treponema were only increased in the S-ALF group at d38. A number of saccharolytic bacteria (Bacteroidaceae), organic acid-producing bacteria (Coprococcus and Actinomyces), proteolytic and amino acid fermenters (Fusobacterium) and fibrolytic bacteria (unclassified Ruminococcaceae) were significantly decreased in the STA lambs but not in the S-ALF lambs at d38. After weaning and exposed to alfalfa, the rumen microbial composition in the STA group started to appear similar to that of the S-ALF lambs. The relative abundance of unclassified Clostridiales was higher in S-ALF lambs than STA lambs after weaning. Spearman’s correlation analysis showed positive relationships between unclassified Lachnospiraceae, unclassified Clostridiales, Treponema, unclassified Bacteroidales, Coprococcus and crude protein intake, neutral detergent fiber intake, and plasma β-hydroxybutyrate. The unclassified Lachnospiraceae and Treponema were also positively correlated with average daily gain. Our results revealed that alfalfa stimulated changes in rumen microbiota during the pre- and post-weaning periods and was consistent with rumen development for better feed intake and animal performance before and after weaning. The findings of this study provide clues for strategies to improve rumen function through manipulation of the rumen microbiota during early life.

Effects of dietary energy level on growth performance, blood parameters and meat quality in fattening male Hu lambs

This experiment was conducted to investigate the effects of different dietary energy levels on growth performance, slaughter traits, meat quality and blood biochemical parameters in fattening male Hu lambs. Sixty lambs were fed five iso-protein diets which contained different levels of metabolizable energy in a completely randomized design for 70 days. At the end of study, fifteen lambs were harvested for further study. With the increase in dietary energy level, the daily weight gain and dry matter intake extremely increased (p < .001), and feed conversion ratio decreased significantly (p < .01). The live weight before slaughter (LWBS) and carcass weight had a significant increase (p < .05), non-carcass fat ratio and routine indexes of meat quality had no significant difference. Almost no effect was observed for the amino acid profile except for glycine concentration decreased (p < .05) in longissimus dorsi (LD) muscle. The concentrations of C17:0, C18:3n-3 and n-3 PUFA (p < .01) significantly decreased with the increasing dietary energy levels, and the ratio of ∑n-6/∑n-3 (p < .01) increased, whereas the concentrations of C18:1n-9t (p < .05) decreased in LD muscle and C18:1 (p < .01) increased in biceps femoris (BF) muscle. There were no obviously differences for diameter, area and density of muscle fibres. The relative expression of MyHC-IIa and MyHC-IIx decreased significantly (p < .05) in BF muscle, and the relative expression of MyHC-IIa displayed an obviously decreasing trend (p < .10) in LD muscle. These results suggest that increasing the dietary energy level can improve the growth performance and slaughter traits, and influence meat quality and fatty acid profiles in different muscle tissues of fattening male Hu lambs. These results provide a theoretical basis for developing Hu sheep nutritional standards and designing feed formulations.

Interaction Between Liver Metabolism and Gut Short-Chain Fatty Acids via Liver-Gut Axis Affects Body Weight in Lambs

The gut-liver axis and its interactions are essential for host physiology. Thus, we examined the jejunal microbiota, fermentation parameters, digestive enzymes, morphology, and liver metabolic profiles in different growth development lambs to investigate the liver-gut axis's role in their development. One hundred male Hu lambs of similar birth weight and age were raised under the same conditions until they reached 180 days of age. Subsequently, the eight lambs with the highest (HADG) and lowest (LADG) average daily weight gains were slaughtered for index assessment. The study indicates that the body weight, carcass weight, propanoic acid, butyric acid, propanoic acid ratio, butyric acid ratio, and digestive enzymes (beta-glucosidase, microcrystalline cellulase, xylanase, and carboxymethyl cellulase) were significantly higher in HDAG lambs than in LADG lambs (p < 0.05). Additionally, there were no significant differences in the jejunal microbiota's structure and function among lambs at different growth development stages (p > 0.05). Overall, our analysis revealed that HADG lambs compared to LADG lambs exhibited an up-regulation of metabolites (such as spermine, cholic acid, succinic acid, betaine, etc.) that were positively correlated with the butyric acid ratio, propanoic acid ratio, propanoic acid, xylanase, microcrystalline cellulase, beta-glucosidase, amylase, carboxymethyl cellulase, carcass weight, and body weight, while these metabolites were negatively correlated with the kidney, acetic acid, acetic acid/ propanoic acid, and acetic acid ratio. Furthermore, there was a significant correlation between liver metabolism and jejunal microbiota. This study revealed significant differences in hepatic metabolites and jejunal fermentation among lambs at different growth stages, which may inform targeted regulation strategies to enhance lamb productivity.

Flax seed meal improved the meat tenderness, nutritional value of fatty acids, and catalase activity of Hu lambs

Thirty male Hu lambs (38.95 ± 3.87 kg; 6 months old) were randomly assigned to two groups: (1) SBM (a basal diet with soybean meal) and (2) FSM (a diet replacing 10 % soybean meal with 10 % flax seed meal) to evaluate their effects on Hu lamb production and slaughter performance, meat quality, muscle fatty acid composition, and antioxidant capacity. The production and slaughter performance, as well as the amino acid composition in muscle were not different between groups. The FSM decreased muscle shear-force (P = 0.019), the pH 24h (P = 0.002), and the cooking loss (P = 0.008). The b* (yellowness, P = 0.039) and the a* (redness, P = 0.008) of the FSM were lower than those of the SBM. FSM group reduced muscle hardness (P = 0.004), gumminess (P = 0.009), chewiness (P = 0.007), and the diameter of muscle fibers (P < 0.05). A significant increase of total n-3 polyunsaturated fatty acids (P = 0.001), the content of α-linolenic acid (ALA, P = 0.003), homo-gamma-linolenic acid (P = 0.034), docosadienoic acid (P = 0.001), and docosahexaenoic acid (DHA, P = 0.003) was obtained in the FSM group. The CAT activity of FSM was significantly higher than that of SBM (P < 0.05). In conclusion, compared with the SBM, the FSM could effectively improve the meat tenderness, the content of ALA and DHA, and the catalase activity in muscle of Hu lambs.