Lesiones en piel por esquila en ovejas Merino australiano gestantes

The study was carried out in at a commercial farm located in the department of Salto, 66 km from the city. Pregnant Merino ewes, 2 to 6 years old (4 to 8 teeth) were used, which were shorn by a company accredited by the Uruguayan Wool Secretariat (SUL). The lesions due to shearing were recorded on a total of 498 ewes, with the objective of evaluating the occurrence of lesions in the different areas of the animal’s body according to the comb used and the skill of the shearer. The shearing was carried out in three days, where each day had four sessions lasting two hours each, and five sessions were evaluated in total. The ewes were shorn at random for both the combs and the shearers, recording approximately a total of 100 sheep per shearer, one shearer shearing 98 sheep, and each one shearing 20 sheep with each of the five evaluated combs (Standard, Cover, Beiyuan, R13 modified and R13), which are the most used combs in Uruguay. The shearers were identified with the letter E and a number (E1, E2, E3, E4 and E5) to maintain the anonymity of each one. This information and the tag number, date, breed, property, comb, type of injury (scratch or cut) were recorded on paper. The lesions were classified as R for scratch (superficial, without cutting the dermis) and T for gash (deep, with a cut in the dermis). They were assigned a number according to the length of the cut (1: < 2 cm; 2: from 2 to 5 cm and 3: > 5 cm). Three effects were analyzed (comb, shearer and session) which were considered as fixed effects in the adjusted models. In turn, body condition (CC) was added as a classification covariate in the analysis, where all the sheep whose CC was below 2.75 and all those sheep that were in a CC greater than or equal to it were grouped together. A binomial model was used to determine the probability of occurrence of the lesions (presence/absence) and a negative binomial model to define differences between the means of lesions for each factor. The comb effect (P<0.0001) and the shearer effect (P<0.0001) presented significant differences. Less than 50% of lesions were recorded both at the ventral and dorsal side, where the frequency of occurrence of lesions at the dorsal side was 49.2% and the ventral one was 43.1%. The most affected region was the Croup, where a higher incidence was observed for all the shearers and for the different combs; on the other hand, the least affected region for all the cases of the different shearers and the different combs was the Udder and Vulva region. The combs that registered the least number of lesions were those that left a greater amount of wool (R13 and Beiyuan), while the combs that left a smaller amount of wool caused a greater number of lesions. These combs were Standard and Cover. The differences between the shearers could be due to the experience and ability of each one of them, which makes the performance of the shearer vary.