Effects of divergent selection for leg weakness on muscle and bone characteristics in Duroc swine

Abstract

The dimensions and weights of front leg muscles, tendons, and bones were determined in 44 gilts that were offspring of three Duroc lines from a five-generation divergent-selection experiment on leg weakness. Lines were low, control, and high, with the low line having the greatest leg weakness and the high-line having the least leg weakness. At a slaughter weight of approximately 118 kg, the right front leg was removed from the carcasses of 14 low-, 16 control-, and 14 high-line gilts. Each intrinsic muscle was dissected from origin to insertion, removed from the leg, and measured for total length and weight. The skeleton of the front leg was disarticulated so that each bone was freed and thoroughly cleaned of muscle remnants and connective tissue. The shoulder and elbow joints were scored for the presence of osteochondral lesions. Each bone was weighed, and various dimensional traits were measured. The model used to analyze the data included the effects of line, sire within line, and weight as a covariate. The biceps brachii muscle weight and length were significantly greater in low-line pigs than in controlor high-line pigs (P < 0.05). Collectively, the forearm extensor weights were significantly greater in low-line pigs than in controlor high-line pigs (P < 0.05). The humeral and metacarpal bones were shorter in high-line pigs than in controlor low-line pigs (P < 0.05). The head of the humerus was wider and the angle of the head of the humerus was greater in high-line pigs than in controlor low-line pigs (P < 0.05). Divergent selection for differing degrees of leg soundness in Duroc swine appears to be associated with major differences in front-leg bone and muscle lengths and weights. pigs / leg weakness / bone / muscle / selection Résumé-Effets d'une sélection divergente pour la qualité des aplombs sur des caractéristiques osseuses et musculaires chez le porc Duroc. Les dimensions et poids des muscles, tendons et os du train antérieur ont été mesurés chez l!l, porcs descendant

A whole genome scan for quantitative trait loci for leg weakness and its related traits in a large F2 intercross population between White Duroc and Erhualian1

“…In this study, the gait score of front legs at 223 d showed a negative correlation with the weight (r = −0.23, P < 0.0001) and length (r = −0.24, P < 0.0001) of the biceps brachii muscle, which was in agreement with the previous report (Draper et al, 1992). However, the front leg score at 213 d had a low and positive correlation with weight (r = 0.10, P < 0.05) and length (r = 0.15, P < 0.001) of the biceps brachii muscle.…”

“…It has been reported that weight and length of the biceps brachii muscle were significantly greater in a leg weakness line than in normal and leg soundness lines (Draper et al, 1992). In this study, the gait score of front legs at 223 d showed a negative correlation with the weight (r = −0.23, P < 0.0001) and length (r = −0.24, P < 0.0001) of the biceps brachii muscle, which was in agreement with the previous report (Draper et al, 1992).…”

“…Artificial selection for production traits also has adverse effects on leg structure of pigs, impairing leg soundness (Lee et al, 2003). Leg weakness can be evaluated with leg and gait scores and is related to weight and length of the biceps brachii muscle (Draper et al, 1992). As a multifactorial trait, the heritability of leg weakness is estimated to range from 0.1 to 0.5 (Bereskin, 1979;Webb et al, 1983;Rothschild and Christian, 1988;Jør-gensen and Andersen, 2000).…”

Mapping quantitative trait loci for principal components of bone measurements and osteochondrosis scores in a wild boar × Large White intercross

“…Many studies of associations between growth rate and osteochondrosis have been performed, the results most often showing weak and inconsistent correlations (Lundeheim, 1987 ;Nakano et al, 1987 ;Hill, 1990 b ;Stern et al, 1995 ;Uhlhorn et al, 1995). Selection for different degrees of leg weakness has been shown to result in alterations in bone length and width (Draper et al, 1992) and in angularity of joints (Draper et al, 1988). However, the correlated response on osteochondrosis was negligible in the same selection experiment .…”

Stereological methods based on point counting and unbiased counting frames for two-dimensional measurements in muscles: comparison with manual and image analysis methods

“…Their measurement can be based on conventional manual methods, automatic or semi-automatic image analysis (e.g. Freilinger et al, 1990;Draper et al, 1991) or on stereological methods (e.g. Egginton, 1990;Kilarski & Sj6str6m, 1990;Mazzoni et al, 1990).…”