Effects of supplementing concentrates with different energy levels on growth performance, blood indicators, and fecal microbiota of Mongolian horses in late gestation.

Overview

• This study evaluates how feeding Mongolian mares with concentrates of varying energy levels during late gestation affects their growth, blood health indicators, and gut microbiota.
• Medium-energy concentrate supplementation was found to improve mare weight gain, nutrient absorption, biochemical health markers, reproductive hormones, and gut microbial composition, suggesting a better nutritional strategy for pregnant mares in challenging environments.

Background and Research Context

• Horses hold cultural, agricultural, and economic importance globally, particularly in regions like Inner Mongolia, China.
• Late gestation is a critical time for mare and fetus health; inadequate nutrition can result in complications such as nutritional abortions and poor foal growth.
• Harsh winters and seasonal pasture shortages in cold climates create nutritional challenges for broodmares, highlighting a need for targeted feeding strategies.
• Previous research in equine nutrition, especially for local breeds like Mongolian horses, has been limited, motivating this study.

Research Design and Methods

• Mongolian broodmares in late gestation were assigned to three supplementation groups receiving concentrates with low (LEN), medium (MEN), or high (HEN) energy levels.
• Growth performance was monitored through final body weight and average daily gain (ADG).
• Nutrient digestibility was assessed, likely via fecal analysis or feed intake measurements.
• Blood biochemical indicators measured included lactate dehydrogenase (LDH) and aspartate aminotransferase (AST), both related to metabolism and tissue health.
• Antioxidant parameters such as catalase (CAT) and malondialdehyde (MDA) evaluated oxidative stress status.
• Reproductive hormones analyzed were follicle-stimulating hormone (FSH), progesterone (P4), and estradiol (E2) to assess reproductive function.
• Fecal microbiota composition was investigated to understand impacts on gut health and metabolism.
• Metabolomic profiling identified differences in metabolic pathways linked to energy and physiology among groups.

Key Findings

• Growth Performance and Nutrient Digestibility
  • Mares receiving medium-energy (MEN) concentrates exhibited significantly higher final body weight compared to low and high energy groups.
  • Tendency toward higher average daily gain (ADG) and better nutrient digestibility in the MEN group suggests improved feed utilization.
• Blood Biochemical Indicators
  • LDH activity was significantly elevated in the MEN group, indicating greater anaerobic glycolysis efficiency and possibly better energy metabolism during late gestation.
  • Lower AST activity in the MEN group suggests reduced liver and muscle stress compared to LEN and HEN groups.
• Oxidative Stress and Antioxidant Status
  • CAT levels increased in the MEN group, implying strengthened antioxidant defenses.
  • Concurrently, malondialdehyde (MDA), a marker for oxidative damage, was lower, indicating reduced oxidative stress.
• Reproductive Hormones
  • The MEN group showed increased follicle-stimulating hormone (FSH), which is important for follicular development and reproductive readiness.
  • Conversely, the LEN group had higher progesterone (P4) and estradiol (E2), hormones associated with pregnancy maintenance and reproductive cycling, which may reflect differing hormonal regulation depending on energy availability.
• Fecal Microbiota and Metabolomics
  • The composition of gut bacteria shifted favorably in MEN-supplemented mares, promoting beneficial species potentially related to improved digestion and immunity.
  • Metabolite profiles differed significantly between groups, aligning with changes in energy metabolism and physiological pathways affected by the energy level of supplemental concentrates.

Conclusions and Global Implications

• Supplementing late-gestation Mongolian mares with medium-energy concentrates effectively supports better growth, metabolic health, and reproductive hormone balance.
• This nutritional intervention reduces oxidative stress and improves the gut microbiome, which could enhance overall maternal and fetal health during a critical reproductive phase.
• The findings have broad relevance for horse breeding in cold or seasonally variable environments worldwide, where pasture quality may be insufficient.
• Implementing medium-energy concentrate supplementation can optimize broodmare nutrition, improve reproductive outcomes, and contribute to sustainable horse industry development globally.
• These results encourage further research and application of tailored feeding strategies aligned with environmental and breed-specific needs.