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 pH 24 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.

The efficiency of Simmentaler cross (SX), Bonsmara cross (BX), Afrikaner (AF) and Nguni (NG) cowherds to produce weaner calves under natural sweetveld conditions was investigated. The respective cowherds were selected to differ with regard to frame size (SX > BX > AF > NG). The AF cows, young (13 to 15 months old) heifers and herd had significantly lower pregnancy rates than the SX, BX and NG cows, young heifers and herds. The weaning rate for NG was significantly higher (15%) than SX, and although not significant, it was still 5 and 8% respectively higher than BX and AF. Weaning weight and pre-weaning growth parameters differed significantly between breed types (SX > BX > AF > NG). Cow efficiency was significantly lower for the AF cows than for the SX, BX and NG cows. The NG herd was more efficient than the other three herds, while the AF herd was the least efficient. Differences in herd efficiency were mainly due to differences in the reproduction rates of the respective herds. The reproduction and calf survival rates were the most important production traits that affected herd efficiency. Management practices should be adapted to maximize the reproduction rate of the females, including the young heifers, to maximise herd efficiency.

A preliminary investigation was done into the possible causes of the increased seismic activity in the Witwatersrand

In the arid sweetveld regions of South Africa producers are marketing beef steers increasingly as long weaners (ca. 12 months of age) or finishing them on the natural grazing to a ready-to-slaughter stage at between 18 and 30 months of age. Limited production norms in this regard are available since most growth and carcass studies have been conducted in the sourveld regions of the country. In this study steers from four different beef maturity types which differ in body frame size were used, viz. Simmentaler crosses (large, >500 kg mature weight), Bonsmara crosses (large-medium, 450-500 kg mature weight), the Afrikaner (small-medium, 400-450 kg mature weight) and the Nguni (small, <400 kg mature weight). After weaning the steers in each type were randomly allocated to three groups, viz. groups slaughtered at 18, 24 or 30 months of age after raising them on natural sweetveld pasture. Live weight, cold carcass weight, carcass fat classification code and number of visible incisors were recorded. Growth rates from weaning to 24 months of age were similar for the different maturity types, though the Afrikaner steers gained significantly less than the Bonsmara crossbreds. Periods where high growth rates occurred (at 12 to 18 months of age and 24 to 30 months of age) coincided with the rainy season. Relatively low dressing percentages were noted and could be attributed to the fact that all internal organs and fat were removed at slaughtering, as well as a possible high level of gut fill. Due to genetic variation within maturity types it was not possible to predict the market readiness of a particular individual from its live weight. The carcass weights were heavier for steers slaughtered at 24 months of age than those at 18 months of age, but had a lower fat classification code. This seems to be due to the fact that these steers were slaughtered at the end of the winter period when the quality of the grazing was at its lowest. The carcasses of all maturity types had the highest fat classification codes at 30 months of age. However, the carcasses of 77.8% of the Simmentaler crossbreds were graded 1 (lean) in the fat classification. Furthermore, at 30 months of age 23.8% of all steers had more than two permanent incisors. This increases their carcass age classification, which lowers their carcass grading according to the South African grading standards, and thus their price per kg relative to the younger ages. The results of this investigation indicated that steers of all frame sizes would have to be fed additional energy to ensure that they finish with a fat classification code of at least 2 before the age of 30 months to ensure optimal financial returns.

No abstract