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

Abstract

Simmentaler cross (SX), Bonsmara cross (BX) and Nguni (NG) steers were raised on natural sweet veld pastures and slaughtered at 18 or 30 months of age. Slaughtering occurred at the end of the wet summer season. Live weight and carcass traits were significantly influenced by breed and slaughter age. The amount as well as percentage kidney and omental fat differed significantly between the respective slaughtering ages, but only between breeds at 30 months of age. Breed and slaughter age affected back-fat thickness. All fat parameters were lower at 18 months than at 30 months of age. Breed did not have a large influence on meat quality attributes, but age did. Drip loss was similar for the breeds and slaughter age groups. The meat was darker and more red at 30 months than at 18 months of age. The pH24 of the longissimus muscle was 5.51 and 5.67 at 18 and 30 months of age, respectively. No breed differences were detected for sensory panel attributes or Warner-Bratzler shear force values. Sensory panel tenderness and Warner-Bratzler shear force values indicated tougher meat from 30-month old steers than from 18-month old steers. Differences in meat quality were probably due to the combined effects of fatness, pH and collagen characteristics. It is concluded that in sweet veld areas steers from small- to medium-framed breeds can be raised successfully and slaughtered at 30 months of age without supplementation of natural pastures. Slaughtering steers at younger ages may require supplementary feeding or feedlot finishing.

Keywords: Beef; carcass traits; meat quality; natural pasture; arid

South African Journal of Animal Science Vol. 37 (3) 2007: pp.143-153