Efecto de diferentes peines y esquiladores sobre las lesiones de esquila en ovinos Corriedale

In this study, data derived from pregnancy shearing of Corriedale ewes were used. The study was done at a sheep farm in the North of Uruguay, 80 km to the east of Salto.  The aim was to evaluate if the occurrence of skin lesions varies according to shearing comb, shearer skill and the zone or area of the body of the sheep. Five-hundred ewes were shorn in five different sessions (n=100), which were randomly assigned to a comb, a shearer in a Latin square design. Therefore, 20 ewes were recorded for each comb, shearer, and session of five levels each, except for the “shearer” treatment which had six levels. The most used combs in Uruguay were tested; the Standard comb, the Snow Cover (Cover) comb, the high shearing Beyuan (Chinese) comb, the R13 comb developed by the Uruguayan Wool Secretariat (SUL) and a new comb modified from the R13. A letter (A to F) was assigned to each shearer to maintain their identity private. A form was used to record tag number, date, breed, farm, comb, type of skin lesion (graze or cut). Lesions were classified as R (rayón = graze, superficial not penetrating the dermis) and T (tajo = cut, deep cut penetrating the dermis). A number was assigned to each lesion according to its dimensions (1: < 2cm; 2: de 2 a 5 cm y 3: > 5 cm). Nevertheless, due to the low frequency of some types of lesions, the different types of lesions were not considered in the analysis. The main effects analyzed were comb, shearer and session. Body condition score (BCS) was included in the model as a co-variable and ewes were grouped by BCS below 2.75 or equal or greater than 2.75. A binomial model was used to determine the probability of occurrence of lesions (present/not present) and a negative binomial model to determine the differences among mean values of lesions according to each factor. The effects of comb and shearer were significant; however, the effect of session was not on all occasions (and was not described in this study) and the effect of the covariable BCS was not significant. Few lesions occurred, independently from comb or shearer, and 54% of the ewes did not present any lesion, and the ewes that did present lesions the majority occurred on the dorsal side. The lesions were concentrated on the hindquarters and the axilla areas, while the udder and vulva areas were the least affected. The best results were obtained with the high shearing combs such as the R13 and the Chinese, which leave a more fleece and induce fewer lesions, in contrast with combs that leave less fleece such as the Standard and the Cover combs which induce more lesions. The differences in number of lesions among shearers suggest differences in skill and experience among them, leading to different performances.