GENETIC AND PHENOTYPIC ASSOCIATION BETWEEN SKIN TEARING AND SKIN COLLAGEN, PROTEIN, AND FAT IN BROILERS

Two crosses of meat-type chickens, selected divergently for low (LF) o r high (HF) abdominal fat, and a commercial broiler cross (CM) were st udied. Protein, collagen, and fat content were determined in skin biop sies taken from 30 random 6-wk-old live males and females from each cr oss. Skin tears following cold-water plucking and protein, collagen, a nd fat content in breast skin samples were determined at 7 wk of age f or another 70 chickens per cross. In each cross, about 100 female offs pring of the chickens sampled for biopsies were also scored for skin t ears and the composition of their breast skin samples. Intact skin was associated with higher collagen and total protein contents and possib ly lower fat. Skin of LF cross chickens had lower fat and higher prote in and collagen contents and 50% lower incidence of skin tears, as com pared with that of HF and CM chickens. Based on parent-offspring corre lations, heritability estimates of .35 to .47 were obtained for protei n content, collagen content, and collagen:fat ratio. Protein and colla gen content in the parents' skin samples were negatively correlated (r values around -.5) with incidence of skin tears among their offspring , whereas a positive correlation (.44) was found with fat content. No correlation was found between offspring's skin tears and parents' body weights. It is concluded that incidence of skin tears could be reduce d by selection on collagen or fat content (or both) of breast skin bio psies taken from live birds, with expected concomitant improvement in carcass leanness.