Carcass length in the bacon pig; its association with vertebrae numbers and prediction from radiographs of the young pig

Abstract

Vertebrae counts made on 504 Large White and 550 (Wessex × Large White) pigs showed an association with carcass length but not with other carcass traits. For each additional vertebra there was an increase in length of approximately 15 mm. Another group of 313 piglets from 36 litters were X-rayed at around 9 days of age in order to predict their ultimate carcass length. After correction for sex and variations in weight at slaughter it was found that the number of thoracic and lumbar vertebrae together accounted for 14% of the remaining variation in carcass length. Improved accuracy of prediction, accounting for 29% of the variation was obtained with a multiple regression equation using as independent variables: the skeletal length of the young pig as measured on its radiograph, its weight at birth and X-raying and the number of lumbar vertebrae. From measurements made on the carcass it i s suggested that X-raying of the bacon pig to measure the length of the first four lumbar vertebrae, would, in conjunction with an earlier determination of vertebrae number, enable a much improved prediction of carcass length to be made. The incidence of various vertebral variations is noted and in particular the occurrence of one pig with only six cervical vertebrae.