Multi-omic analysis reveals that the <i>CARNS1</i>-mediated carnosine synthesis pathway modulates muscle metabolic responses to nutrient restriction in goats.
Maintaining feed intake at a minimum of 75% during seasonal feed shortages may prevent irreversible muscle damage in goats.
Where it sits
this study against the rest of the matrixyl corpusSummary and findings
This study investigated the effects of varying degrees of nutrient restriction on muscle metabolic responses in goats. Thirty male Xiangdong black goats were subjected to normal feeding, 25% restricted feeding, and 50% restricted feeding over an 87-day period. Significant impairments in growth and muscle morphology were observed, particularly in the 50% restricted feeding group.
Abstract
Seasonal feed shortages pose critical challenges to ruminant productivity, yet the mechanisms underlying muscle metabolic responses to varying degrees of restriction remain unclear. This study simulated feed shortage in goats using three dietary treatments: normal feeding (RF0), 25% restricted feeding (RF25), and 50% restricted feeding (RF50). A total of 30 male Xiangdong black goats with similar initial body weight (19.14 ± 2.75 kg) and age (4.0 ± 0.3 months) were randomly assigned into 3 groups (<i>n</i> = 10 per group) for an 87-d trial (7-d preliminary period followed by an 80-d experimental period). By integrating growth performance, muscle morphology, fatty acid and free amino acid profiles, and transcriptomic and metabolomic data, the multilevel responses of goat muscle to feed shortage were characterized. As anticipated, restricted feeding markedly impaired growth performance; in particular, the average daily gain in the RF50 group decreased markedly compared with the RF0 group (<i>P</i> < 0.05). Morphological analysis revealed that RF50 significantly reduced the cross-sectional area of longissimus lumborum muscle fiber (<i>P</i> = 0.017) without affecting fiber diameter or density (<i>P</i> > 0.05) compared with the RF0 group, suggesting that structural preservation of fiber number was prioritized over individual fiber volume under severe nutritional stress. Metabolically, RF50 induced accumulation of free amino acids (aspartate, glycine, valine, and lysine) and monounsaturated fatty acids (cis9-C16:1n-7 and cis9-C18:1 n-9), and depletion of polyunsaturated fatty acids (cis9,cis12-C18:2n-6 and cis9,cis12,cis15-C18:3n-3) compared with the RF0 group (<i>P</i> < 0.05). Transcriptomic analysis revealed suppression of protein processing in the endoplasmic reticulum, beta-alanine metabolism, PPAR signaling pathway, aminoacyl-tRNA biosynthesis, fatty acid metabolism, and fatty acid degradation pathways under RF50 (<i>P</i>-adjust < 0.05); concordant downregulation of the beta-alanine metabolism and aminoacyl-tRNA biosynthesis pathways was also observed in the metabolome. Trend clustering identified a nonlinear metabolic threshold, with RF25 inducing gradual adaptations while RF50 triggered abrupt metabolic reprogramming. Integrated multiomics analysis identified the beta-alanine metabolism pathway as a pivotal hub, marked by coordinated downregulation of <i>CARNS1</i> and significantly reduced levels of carnosine and L-histidine in the RF50 group (<i>P</i>-adjust < 0.05). These findings suggest that severely restricted feeding disrupts muscle homeostasis via the <i>CARNS1</i>-mediated carnosine synthesis pathway, impairing fatty acid metabolism and protein turnover. The adverse effects of RF50 on muscle characteristics were more pronounced than those of RF25, indicating that maintaining feed intake at a minimum of 75% during seasonal feed shortages may prevent irreversible muscle damage and mitigate nutritional stress in goats.
Background
This paper addresses the impact of seasonal feed shortages on ruminant muscle metabolism, a critical issue for livestock productivity. Previous research has shown that nutrient restriction can affect growth and muscle development, but the specific metabolic pathways involved remain poorly understood. This study aims to elucidate these mechanisms through a multi-omic approach in goats.
Methods
The study utilized a randomized design with 30 male Xiangdong black goats, divided into three groups (n=10 each) subjected to normal feeding, 25% restricted feeding, and 50% restricted feeding over an 87-day period. The primary outcomes included growth performance, muscle morphology, and metabolic profiling, assessed through transcriptomic and metabolomic analyses.
Results
The average daily gain in the RF50 group decreased markedly compared with the RF0 group (P < 0.05). The RF50 group exhibited a significant reduction in the cross-sectional area of longissimus lumborum muscle fiber (P = 0.017) without affecting fiber diameter or density (P > 0.05). Metabolically, the RF50 group showed accumulation of specific free amino acids and depletion of certain polyunsaturated fatty acids (P < 0.05).
Interpretation
The findings suggest that severe dietary restriction leads to significant metabolic disruptions in muscle tissue, particularly through the downregulation of the beta-alanine metabolism pathway. While the statistical significance of the results is clear, the clinical relevance may be limited by the small sample size and the specific population studied. These results highlight the need for adequate feeding strategies to prevent muscle damage during periods of nutritional stress.
Key findings
- Average daily gain in the RF50 group decreased markedly compared with the RF0 group, P < 0.05.
- Cross-sectional area of longissimus lumborum muscle fiber in the RF50 group was significantly reduced compared with the RF0 group, P = 0.017.
- Accumulation of free amino acids (aspartate, glycine, valine, and lysine) was observed in the RF50 group compared with the RF0 group, P < 0.05.
- Depletion of polyunsaturated fatty acids (cis9,cis12-C18:2n-6 and cis9,cis12,cis15-C18:3n-3) was noted in the RF50 group compared with the RF0 group, P < 0.05.
- Downregulation of the beta-alanine metabolism and aminoacyl-tRNA biosynthesis pathways was observed under RF50, P-adjust < 0.05.
Limitations
- small sample size of 30 goats
- specific focus on a single species
- short-term feeding trial may not capture long-term effects