**2. Materials and method**

The experiment was conducted at the University of Zululand farm (South Africa), 28.8500° S, 31.8333° E in the small ruminant section. Eight rams of the same age (3 years) were used. To determine the social rank, the feed competition method by Maksimović et al. [2] was used. To initiate aggressive behaviour rams were subjected to fasting for 12 hours before data collection session. However, water was provided *ad libitum*. The feed was put in an immovable concrete container. Before the experiment commenced, body weight, pelvis length, horn size and chest girth were measured in all rams. To simplify observations and analysis, the animals were recorded by a CCTV camera giving a clear view as the animals entered the feeder site and during feeding [8]. After the experiment, the video was watched and analysed for evidence of dominant interactions. The position and time spent at the feeder by animals were also analysed. Furthermore, the activities of each ram were described using the method of Squires and Daws [8]. Each ram's activities were categorised as follows: (a) retained a fixed position at the feeder trough, (b) evacuated from the feed trough, (c) attempted re-entry on the feed trough and (d) on the edge. As ram entered the feeder, their identification number was noted and time spent in all four categories was recorded. Time spent by rams was recorded as they forced their way to the feeding trough, or attempted to enter the feeder, between adjacent aligned rams at the feeder. The ram trying to search for a space at the feeder was also noted. The number of contests between two rams was recorded, with a dominant and subordinate ram identified.

### **3. Statistical analysis**

Data were analysed using SPSS. The number of contests and wins was recorded for each sheep. The number of wins was converted to a proportion and the binomial test was used to compare against the expected number of wins. A Pearson correlation analysis was used to test the relationship between body measurements, proportions of wins and minutes spent at the feeder.

### **4. Results**

**Tables 1** and **2** show the dominance-subordinate relationship in Zulu sheep rams. Ram A was ranked first with a 100% number of wins (*P* < 0.01) followed by Ram E with an 86% number of wins (*P* < 0.05). Ram D was ranked number 6 with only one win out of seven (*P* < 0.01). From the behavioural observations, rams divided themselves into two groups when they were introduced to the feed. The first group rapidly entered the feeder whereas the second group remained on the edge of the feeding trough or tried to find a space in the feed trough. Rams at the edge of the feeding trough struggled to push their heads in it by fighting rams, which were already feeding, but while trying to get to the feeding spot other rams pushed them

#### *Social Dominance in South African Indigenous Zulu Rams DOI: http://dx.doi.org/10.5772/intechopen.103014*


*Reading across: + = dominant and* − *= subordinate. Reading down: + = subordinate and* − *= dominant. Blank spaces indicate that no contest was observed. NS = not significant.*

*\*These results emanate from our own experiment.*

*\*\*P<0.05.*

*\*\*\*P<0.01.*

#### **Table 1.**

*Dominance-subordinate relationship in Zulu sheep rams\*.*


#### **Table 2.**

*Percentage of time spent at the feeder and in seeking re-entry\*.*

away. Throughout the feeding, there were contests and pushing between individuals. Due to the overcrowding at the feed trough, very few rams were able to occupy one spot without being pushed away. However, some rams were able to maintain their position at the feeder by positioning themselves laterally. In some instances, due to the need to feed and the pressure at the feeder, some rams (second group) gained access to the feeding trough by forcefully pushing their heads between two closely aligned individuals. Rams, which struggled to enter the feeding trough, were hindered by adjacent individuals, which were closely aligned to another ram, thus subsequently blocking entry to the feed trough. The behavioural sequences were complex at the feed trough, when one ram forced his way to the feeder; one or more rams lost their spot at the feeder. A dominant-ranking ram (i.e., Ram A) caused low-ranking rams to be submissive and flee. Submissive or subordinate rams were

#### **Figure 1.**

*Association between the proportion of wins and time at the feeder for each ram\*. \*These results emanate from our own experiments.*

reluctant to try to find a feeding spot near the dominant ram due to the threatening behaviour displayed by the high- ranking ram. However, the submissive ram sometimes would wait for the dominant ram to stop its threatening behaviour and turn its head to feeding, and then a submissive ram would quickly move into the available feeding spot by doing so it would be allowed to stay and feed.

As shown in **Figure 1**, a relationship between time spent on the feeder against the number of wins was not significant (*P* > 0.05). **Table 3** exhibits a correlation between physical traits of Zulu sheep rams with proportions of wins and minutes at the feeder. There was a significant positive correlation between the proportions of


*\*\*P < 0.05. \*\*\*P < 0.01.*

#### **Table 3.**

*Correlation between physical traits of Zulu sheep rams with proportions of wins and minutes at the feeder\*.*

wins against horn length (*P* < 0.05) and chest girth length (*P* < 0.05). Body weight was positively correlated with wither height (*P* < 0.05), Scrotal circumference (*P* < 0.05), chest girth (*P* < 0.05) and time spent at the feeder (*P* < 0.05). Withers height was positively correlated with time spent at the feeder (*P* < 0.05). There was a positive correlation between scrotal circumference and horn length.
