Muscle Growth and Distribution in Fattening Steer of Different Breeds

Abstract

The breed pa erns in growth and distribution of muscle were studied using three breeds of beef ca le entering fa ening phase. This study involved 23 grass-fed steer Brahman, 24 Hereford and 22 Brahman x Hereford crosses with a live weight range of 300 to 600 kgs. An allometric Huxley model was used to study the growth and distribution pa erns of muscle tissue within wholesale cut. There were several cuts in which the muscle growth coeffi cients were signifi cantly diff erent among breeds. Comparisons of muscle weight distribution at log natural of 75 kg side muscle + bone weight (4.313 kg) generally showed signifi cant between-breed diff erences. Herefords tended to have more muscles in their wholesale cuts than Brahmans and/or Brahman x Hereford crosses, except the muscles in Tenderloin, Rib Set and Chuck. Brahmans had heavier Topside and Silverside than Herefords and Brahman x Hereford crosses and the diff erences were maintained at log natural of 114 kg side muscle + bone weight (4.733 kg). At this heavier weight, there was a general tendency for Brahmans to have more muscle in their wholesale cuts than the Brahman x Hereford steers, except the muscle in Loin and Neck + Sticking.

The Growth and Distribution of Carcass Fat in Fattening Steer of Different Breeds

“…Unlike the growth of muscle within wholesale cuts (Priyanto & Johnson, 2011), the growth of fat showed more widespread breed variations, 11 of the 15 wholesale cuts differing significantly among breed groups (Table 1). In most cases, Brahmans had significantly higher growth coefficients than Herefords and/or BrahmanxHereford crosses while Herefords and BrahmanxHereford crosses had similar growth coefficients in wholesale cuts.…”

“…Whilst such studies could provide useful information about patterns of fat growth and distribution, the genetic variation in fattening patterns could not be clearly identified by this approach. Priyanto & Johnson (2011) reported breed variation in muscle weight distribution whitin wholesale cuts when adjusted to the same carcass weight. The present study confirmed the previous findings that there were significant between breed differences in the growth and distribution of carcass fat whitin wholesale cuts relative to fat-free carcass weight.…”

“…Fat-free carcass weight was as an effective adjustment factor in breed comparison for muscularity and muscle to bone ratio (Purchas Purchas et al, 2002). Previous finding showed significant but small between breed differences in the muscle growth and distribution relative to fat-free carcass weight (Priyanto & Johnson, 2011). In this study, the influence of beef cattle breed on carcass fat and its distribution throughout the wholesale cuts relative to fatfree carcass weight was examined in fattening steer.…”