Effects of Feeder-Cattle Frame Size and Muscle Thickness on Subsequent Growth and Carcass Development. I. An Objective Analysis of Frame Size and Muscle Thickness

Abstract

A multivariate analysis was performed to provide objective descriptions of visually perceived differences in feeder-cattle frame size and muscle thickness. Three hundred and twenty-four yearling feeder steers were selected to represent USDA classifications for frame size (Large, L; Medium, M; Small, S) and muscle thickness (No. 1, No. 2 and No. 3). The frame-size classification (F) of each steer was determined by a subjective evaluation of skeletal size-height and length-in relation to maturity; the muscle-thickness classification (M) was based on a visual assessment of thickness of the rear quarter, forearm and gaskln-due to muscle expression and independent of differences in fatness-in relation to skeletal size. Six dimensional measurements (heart girth, hip width, stifle width, forearm circumference, body length and hip height) and a measurement of subcutaneous fat thickness (fat probe) were recorded for each steer to obtain objective assessments of traits that were emphasized during visual classification. A canonical varlate analysis was performed on the system of body measurements to quantify differences in feeder-cattle size and shape corresponding to USDA descriptions of frame size and muscle thickness. Over 95% of the dimensional variation among the nine F X M subclasses (L-No. 1, L-No. 2... S-No. 3) was explained by the first two canonical vatiates. The first canonical variate (Zt) described morphological differences correspondingto variation in frame size and primarily reflected differences in absolute stature (L>M>S). Moreover, Z~ revealed a latent tendency for cattle of different frame sizes to vary in relative body dimensions (length, width and girth in relation to height). These relative dimensional differences were attributed to variation in developmental status. The second canonical variate (Z a ) primarily contrasted variation in rear-quarter thickness (relative to skeletal size) and shape corresponding to visually perceived differences in muscle thickness. Cattle perceived to be thickly muscled (No. I muscle thickness) had disproportionately wide and convexly shaped rear quarters, while steers classified as thinly muscled (No. 3 muscle thickness) were relatively narrow and flat through the rear quarters. Circumference of the forearm received secondary emphasis for discriminating among muscle-thickness groups. Evaluations of muscle thickness did not appear to be influenced by variation in subcutaneous fat thickness. Results of the analysis were used as an objective basis for interpreting the effects of feeder-cattle frame size and muscle thickness on subsequent growth and carcass development. (

Effect of slaughter age and breed on the carcass traits and meat quality of beef steers finished on natural pastures in the arid subtropics of South Africa

“…Heavier (P < 0.05) LW and carcass weights have been reported for large-framed steers than for small-framed steers at a constant age (Wheeler et al, 1996;Camfield et al, 1999;Short et al, 1999) as well as at a constant carcass fat content (Tatum et al, 1986b;Dolezal et al, 1993;Wheeler et al, 1996). Bidner et al (1986) reported similar LW for pasture raised Angus x Hereford and Brahman cross steers at 31 months of age, as was observed for SX and BX steers in the present study.…”

“…Strydom et al (2001) reported higher carcass compactness for Bonsmara (0.91 to 0.94) and Nguni (0.74) bulls than was observed for 30-month old steers in the present study. The observed differences in Tatum et al (1986b) who indicated that there is a strong correlation (r = 0.96) between hip height and frame size, but a low correlation (ranging from 0.09 to 0.48) between other body measurements (body length, width and girth) and frame size. They indicated that although all body measurements increased with an increase in frame size, body length, width and girth were not always proportional to corresponding differences in heights.…”

Influence of Diet on Growth Rate and Carcass Composition of Steers Differing in Frame Size and Muscle Thickness

“…As a result, frame size was confounded with breeds, which differed in mature size, whereas variation in muscle thickness tended to contrast calves of conventional beef breeding with those of dairy and Longhorn breeding. Such confounding effects and their implications concerning interpretation of results were discussed previously by Tatum et al (1986b).…”

Size and shape analyses in hair sheep ram lambs and its relationships with growth performance

“…A related procedure, canonical discriminant analysis, has been used to examine the between-class variation in a system of body measurements in beef cattle (Tatum et al, 1986;Gilbert et al, 1993) and sheep (Traoré et al, 2008). Canonical discriminant analysis transforms the original variables into a smaller number of composite variates, or canonical variables, that emphasize the between-class variation, as opposed to principal component analysis, which characterizes the total variation.…”