Date of Award
Master of Science (MS)
Fisheries, Animal and Veterinary Science
Murn M. Nippo
Although sheep are thought to be the first domesticated food animal, and have been around for thousands of years, little is known about their social structure. Knowing some of the behaviors exhibited by sheep has already helped shape modern animal husbandry. Becoming familiar with more of the vast array of social behaviors used by sheep could benefit animal husbandry even further. In the wild, sheep graze on large areas of land where there is little competition for food. However, some domesticated sheep spend very little time on open ranges and are often and are often forced to compete over condensed sources of food such as grain, in small troughs. Unnatural competition can lead to potential problems. The most significant problem that develops from competition is that dominant animals may be able to get a large amount of feed, while more subordinate animals may not get any at all. This can also pose problems in the growth rates of domestic sheep. Problems can also escalate when it comes time to breed sheep. Subordinate ewes may not be getting the feed they require to produce healthy offspring. If births do not go smoothly, the ewes still may not be able to supply enough milk to their offspring to keep them healthy.
Animal husbandry may be improved if there is a way to identify the most dominant and subordinate animals in the flock. We do know hat dominance hierarchies do exist in domestic sheep flocks. These hierarchies can be bidirectional or non-linear so that dominance over one another is not always absolute. It is a complicated system that deserves to be examined. To learn more about the social structure of the domestic sheep, an observational study with the Dorset ewes on Peckham Farm at URI was conducted.
Several initial observations were made to become familiar with the most commonly used behaviors. After the behaviors were identified, the ewes were labeled with a special wax crayon so they could easily be distinguished from one another without disturbance. The ewes had been previously kept in two different pens. They were not moved because they had already established social relations with one another. Also, keeping them separate meant there weren't too many for one person to keep track of. A worksheet was constructed in which the behaviors each had their own column. Then, in one-hour increments the identification numbers of the sheep who had exhibited the behavior(s) was documented. After sixty hours of observations were complete, the data was analyzed.
There were two dominant behaviors that were statistically significant for the different age groups of sheep and four behaviors, three of which were dominant, that were statistically significant for the weights of sheep. Correlations tables show positive correlations between dominant behaviors and age, and positive correlations between both dominant and subordinate behavior and weights. Because there was a statistical significance between dominant behaviors and aspects of weight and age, there is evidence of a dominance hierarchy within the domestic flock. It is not certain if the dominance is based more on age or weight and appears to be a combination of them both.
Adams, Shole Cody, "Analysis of Allelometric Behaviors and Social Organization in Domestic Sheep" (2001). Open Access Master's Theses. Paper 837.