A general method is developed for the evaluation of herd efficiency in terms of efficiencies for growth and reproduction. Almost the only requisite knowledge for the application of this method is the value of the allometric slope between the cost…
Genetic evaluation systems require the accurate estimation of genetic parameters. The genetic, phenotypic and environmental parameters for live weight and objectively measured wool traits were estimated for a South African Merino flock. Records of the Tygerhoek Merino resource flock were…
A selection and line x environment interaction study with grade Afrikaner cattle was established in 1956 at Matopos Research Station, Zimbabwe. Two selection lines of 100 cows each were reared in different management environments. The non-supplemented (NS) line relied on…
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…
Weaning performance of calves sired by Charolais and Hereford on dams of Angus, Bonsmara and Hereford and various crossbred dam combinations was compared. Charolais sired calves were on average 5 kg heavier at birth and 20 kg heavier at weaning…
The aim of this study was to evaluate the effect of supplementary light on the performance of bulls in a feedlot. Feed intake (FI), average daily gain (ADG), back fat thickness (BFT), eye muscle area (EMA), P8 (fat layer on…
The objective of this research was to validate the maternal breeding value for preweaning gain as a predictor of genetic differences in milk production. Phenotypic variation in preweaning gain and in milk production measured by the weigh-suckle-weigh method was partitioned…
Inbreeding levels and their possible influence on growth traits of the South African Brahman cattle were investigated. Data utilized in this study consisted of 180264 pedigree (1955 – 2002), 41509 birth weight (BWT), 37705 200-days weaning weight (200d), 22682 400-days…
In general ram semen does not cryopreserve acceptably in terms of post-thawed survival and fertilization. In South Africa it is common to feed high energy diets to breeding rams in performance testing schemes and in preparation for shows and sales,…
Accurate genetic parameters are vital for genetic prediction, selection on breeding values and creation of selection objectives. Consequently, records for birth weight (BW), 200 (WW), 400 (YW) and 600 (FW) day weight were analyzed to obtain heritability estimates. These records…
A dose-response trial was conducted with dairy cows on six farms in the Ixopo district of the Midlands of KwaZulu-Natal. Up to 30 cows per farm received a single subcutaneous injection of 5 mL of a long-acting/slow-releasing selenium (Se) supplement…
This study was undertaken to determine the influence of three grazing pressures [high (HGP), medium (MGP) and low (LGP), corresponding to 30, 50 and 75 g available DM/kg BW/day, respectively] on the quality of herbage consumed by lambs grazing Lolium…
This study was undertaken to determine the influence of three grazing pressures [high (HGP), medium (MGP) and low (LGP), corresponding to 30, 50 and 75 g available DM/kg BW/day, respectively] on the performance of lambs grazing Lolium perenne and Dactylis…
This study was undertaken to determine the degradation characteristics and in vitro gas production kinetics of drought tolerant shrubs (Cassia sturtii, Atriplex nummularia and three Atriplex canescens cultivars, viz. Santa Rita, Field Reserve 1 and Rincon) growing under South African…
A primary objective of commercial pig production is lean meat yield in order to satisfy consumer needs. The majority of the commercial pig breeds in South Africa have been selected for high lean growth potential and reduced backfat thickness. There…
Growth and carcass characteristics of three Ethiopian goat breeds, the Afar, Central Highland (CHG) and Long-eared Somali (LES) were evaluated using three grainless diets varying in concentrate:roughage ratios (diet 1 was 50:50, diet 2, 65:35 and diet 3, 80:20) under…
Sheep from a Merino selection experiment at the Tygerhoek research farm in the Southern Cape provided material for this study. The selection lines involved included a line selected for clean fleece weight, a "Wet and Dry" line, a fine wool…
The study was conducted to measure the development of several testicular characteristics and to investigate the relationship between testicular parameters with body growth, semen characteristics and serum testosterone levels in growing ram lambs. Seventeen single born Kivircik ram lambs from…
Live, carcass, leg and muscle weight (kg) as well as dressing percentage were compared between South African Black (Struthio camelus var. domesticus) ostriches, purebred Zimbabwean Blue Neck (Struthio camelus australis) ostriches and the progeny of Zimbabwean Blue Neck males crossed…
