Horse owners observe different management practices to reduce calorie intake especially for obese horses, and this may include restricting access to pasture with the use of a grazing muzzle.
However, research studies reveal that horses usually increase pasture feeding when they go back to being unrestricted.
Drastic changes in grain feeding practices are known to bring about digestive problems, specifically hindgut health, so researchers started a study to find out if drastic changes in pasture feeding can also bring about similar consequences.
The research was led by Paul D. Siciliano, PhD, an associate professor in North Carolina State University Department of Animal Science. In the study, six mature light horse geldings, weighing the same and have similar body conditions, were separated into two groups.
Pasture Restrictions: The experiment
The control group was given continuous access to pasture while a restricted group was in a grazing muzzle about 12 hours each day. The study went for 7 days; after which, both groups switched protocol for another 7 days. On the seventh day of each period, samples of blood and feces were collected at different intervals to determine plasma protein and fecal pH. Moreover, pasture samples were gathered to analyze its chemical composition.
Once testing was done, results showed the team that horses with restricted pasture access and put on grazing muzzle for 12 hours a day do not have compromised hind-gut health when compared to those horses with unrestricted pasture access. In addition, it was reported that there was no significant difference in the fecal pH – which is an indicator of fermentation in the hind-gut influenced by the composition of the diet - between the control group and the restricted horses.
Another finding in the said study involved the volume of blood plasma protein, which measures hind-gut fluid balance. When feed intake is reduced, it can result to reduced water intake, thus increasing volume of plasma protein. An increased feeding after restriction can increase the secretions of the digestive system; therefore, it decreases plasma protein volume. In this study, research team did not find that plasma protein volume was affected by the treatment group, hence fluid balance is maintained. On top of that, fecal dry matter percentage did not differ in these two groups, further giving support that fluid balance is not affected when restricting access to pasture.