The Horse Gut Microbiome Responds in a Highly Individualized Manner to Forage Lignification.

The researchers investigated how changes in the lignin content of alfalfa hay alter the gut microbiome in horses and found that the impacts were individual and unique to each horse, potentially affecting digestion and other health factors.

Research Context

• Understanding the role of the equine gut microbiome in the utilization of forage is a well-established field. However, the effects of lignification in alfalfa (Medicago sativa L.) on the equine gut microbiome is relatively unknown.
• Alfalfa is a commonly used forage for horses, and this research investigates the changes in the horse gut microbiome when fed reduced lignin (RL) and conventional (CON) alfalfa hays.
• Lignin, an essential component of plant cell walls, can inhibit the digestion of cell wall carbohydrates. Therefore, variation in lignin content could potentially impact gut microbiome composition and animal health.

Research Methodology

• The researchers conducted a crossover study using six adult stock-type horses, feeding them RL and CON alfalfa hays in separate periods.
• Each period consisted of a 9-day dietary adaptation phase followed by a 5-day total fecal collection phase. The horses were individually housed, and their manure was continuously collected, mixed, frozen, and processed for MiSeq sequencing. This allowed for a comprehensive analysis of their gut microbiome.

Findings

• The study found that varying the lignin content of alfalfa hay did not equally affect the gut microbiome across all horses. Instead, each horse’s microbiome responded in a unique and individualized manner.
• Specific changes in the abundance of certain kinds of bacteria including Akkermansia, Fibrobacter succinogenes, Treponema, and Paludibacter were observed when horses were fed RL alfalfa. These patterns were unique to each individual horse.
• Furthermore, the study also noted horse-specific associations between gut microbiome traits and characteristics of the digested alfalfa. These were mainly observed in factors such as dry matter digestibility and mean fecal particle size.

Implications

• These findings indicate that the gut microbiome of horses responds uniquely to changes in the amount of acid detergent lignin in alfalfa hay, which may potentially impact feed digestibility and affect horse health.
• This individualized response to dietary variation suggests a complex and personalized interplay between diet, gut microbiome, and health in horses.
• However, the study concludes that the broader implications of these horse-specific responses on metabolic health and performance are yet to be fully understood and should be the focus of further research.