Maintaining muscle mass is a critical aspect of equine health, particularly as horses age. This study investigates the effectiveness of supplementary amino acids (AA) in supporting muscle mass in horses of varying ages. The findings suggest that targeted AA supplementation can significantly aid in muscle preservation, offering valuable insights for horse owners and caretakers.
Study Design and Methodology
The research involved sixteen light horse breeds subjected to a 2×2 factorial design, considering two age groups: younger horses (≤ 10 years, average 9.1 years) and older horses (≥ 20 years, average 22.4 years). These were further divided into two diet groups: a control group receiving no supplementation (N) and a supplemented group (S) receiving 20.0 g/d of lysine and 15 g/d of threonine. The study spanned 14 weeks, during which all horses maintained a regular exercise regimen.
Throughout the experiment, body weight (BW), body condition score (BCS), and venous blood samples were collected bi-weekly. Plasma analysis included total protein, albumin, creatinine, blood urea nitrogen (PUN), and a detailed amino acid profile, focusing on 3-methyl histidine (3MH) and sulfur amino acids. To objectively assess muscle mass, photographs taken at the beginning and end of the study were used to assign a subjective muscle mass score, ranging from 1 (lowest) to 5 (highest).
Key Findings on Muscle Mass and Body Condition
While the diet type did not significantly alter overall body weight, the supplemented group (S) showed a trend towards weight gain (6.91 ± 2.3 kg), whereas the control group (N) experienced weight loss (-11.76 ± 5.2 kg).
Analysis of body condition revealed that older horses generally had a lower BCS compared to younger horses (P = 0.001). More notably, horses in the supplemented group (S) exhibited a lower BCS than those in the non-supplemented group (N) (P = 0.026).
Subjective muscle mass scores, which were comparable at the study’s outset, were significantly higher in the supplemented group (S) by the end of the experiment (3.77 ± 0.13) compared to the control group (N) (3.28 ± 0.14) (P = 0.047). This indicates that AA supplementation helped horses maintain or even improve their muscle mass.
Biochemical Indicators of Muscle Metabolism
Plasma analysis provided further evidence supporting the beneficial effects of AA supplementation. Plasma creatinine levels were higher in the supplemented group (S) (P = 0.032), suggesting increased muscle metabolism or turnover. Conversely, PUN levels were lower in the S-group (P = 0.027), potentially indicating more efficient protein utilization.
The concentration of 3MH, a marker for muscle protein breakdown, was found to be lower in the supplemented group (S) at the end of the experiment (P = 0.016), further reinforcing the notion that these horses experienced less muscle degradation. Additionally, plasma concentrations of lysine and threonine were significantly greater in the S-group at the study’s conclusion compared to the N-group (P = 0.023 and P = 0.009, respectively), confirming successful supplementation.
Correlation analysis revealed a negative relationship between both 3MH and PUN concentrations with lysine and threonine intake at the study’s end. This highlights that higher intake of these key amino acids was associated with reduced markers of muscle breakdown and improved protein metabolism.
Conclusion: Amino Acids for Muscle Health
The data strongly suggest that supplementary amino acids, specifically lysine and threonine, play a vital role in helping horses maintain muscle mass, irrespective of age. The observed improvements in muscle mass scores, coupled with biochemical markers such as greater creatinine, lower 3MH, and lower PUN concentrations in the supplemented group, underscore the significance of adequate AA intake for equine muscle health. These findings are particularly relevant for owners of aging horses, where muscle maintenance can be a challenge.
For owners looking to optimize their horse’s nutrition, understanding the role of specific amino acids is crucial. Further exploration into equine dietary needs, especially concerning protein and amino acid balance, can be found in resources related to horse breeds worksheet. This study provides a solid foundation for considering AA supplementation as a strategy to support the long-term well-being and performance of horses.
