Twenty sheep, ranging in body mass from 25 to 62 kg, were slaughtered to compare two methods of estimating the chemical composition of the carcass. One half of each carcass was ground in a carcass grinder equipped with a 6…
The effect of different shelters, that is, a shade structure (3.5 m high) in a dry lot and a tie-stall barn in comparison to a dry lot with no protection against climatic conditions (rain and wind), on the milk pro¬duction…
The influence of two scenarios of mortality rates (assumed average and observed) on total herd efficiency of the four main breed types in South Africa (Sanga/Zebu, composite, British and European), as well as all the individual breeds participating in the…
The production performance of primiparous Holstein Friesland and Jersey cows wascompared under local conditions during summer. A complete diet providing 15% crude protein (CP), 13% crude fiber (CF) and 10.8 MJ ME/kg dry matter (DM) was fed twice daily on…
Weaning weight records available for the South African Mutton Merino breed wereutilised to investigate the possibility of a genotype by environment interaction in the breed. A direct heritability estimate of 0.308 ± 0.022 was obtained. Including flock-year-season x sire interaction…
Heritability estimates and breeding value predictions of Dormer sires for litter size and lamb mortality were obtained using a threshold model. Heritability estimates on the underlying scale were 0.24 and 0.12 for litter size and mortality, respec¬tively. Breeding value predictions…
Direct and maternal variance components and resulting heritabilities were estimated by DFREML-procedures for clean fleece weight (CFW), body weight (BW) and mean fibre diameter (MFD) in the Grootfontein Merino stud. Direct heritabilities were estimated as 0.381, 0.289 and 0.626 for…
Rumen fermentation was studied during three years in lactating Dorper and Merino ewes, supplemented daily with crude protein and/or energy via rumen fistulae on veld. Herbage, collected with oesophageally fistulated wethers, and maize meal were incubated in sacco in the…
The reproductive performance of cows with post parturient metritis treated systemically with long-acting oxytetracycline was compared with normal herd mates in four South African dairy herds. The incidence of metritis for all calvings in these herds was 7.5% (of 1838…
A study was conducted to estimate the response to selection on BLUP of breeding values for mature body weight (BW), clean fleece weight (CFW) and mean fibre diameter (MFD) in a commercial Merino stud with a high culling rate on…
In conservation and breeding, large populations are important for evolutionary viability and selection progress. On the other hand, practical and economic reasons may exist for population subdivision. These populations (islands) may be tied together to form effectively a single population…
Productivity of Simmentaler heifers, first mated at 14 months of age (2 M) compared to the traditional system of mating at 26 months of age (3 M), was investigated under extensive farming conditions. Both first calving (60.8 vs. 79.5%) and…
The influence of replacement rate (R), price (c/kg carcass weight) and two production systems on total herd efficiency was investigated. R was assumed to be either 15% (minimum), 19% (point in between) or 23% (maximum). Percentage differences (minimum, point in…
Four laying strains were evaluated with regard to henday egg production, egg mass, feed conversion, mortality, Haugh units, shell thickness and percentage soiled, cracked and broken eggs produced under a battery, floor house and free-range system. This was done to…
Water intake, efficiency and consumption of 30 growing individually fed Blackhead Persian, Dorper and South African Mutton Merino (Mutton Merino) ewe lambs were investigated. Average daily water intakes were 2.2, 4.6 and 5.4 litre for the Blackhead Persian, Dorper and…
The relationships (during summer) between the water solubility of Cymbopogon-Themeda veld grass, Digitaria eriantha (finger grass) and Medicago sativa (lucerne) and their respective contents of crude protein (CP), acid-detergent fibre (ADF) and neutral-detergent fibre (NDF) were determined in samples which…
In each of three consecutive years (1987/88 to 1989/90), 108 weaner steers (average live mass = 192.5 and standard deviation = 1.9 kg) were divided into three groups of 36 steers and fed to achieve growth rates of 0, 0.3…
Forty-eight yearling steers (average live mass = 192.8 and standard deviation = 3.7 kg) were blocked by mass and breed [Sussex (n = 32) and Simmentaler (n = 16)] and within blocks allocated randomly to one of four treatments (supplementation…
Research on ruminant nutrition in South Africa is reviewed for the decade 1985/1995. The review covers the following topics: feed requirements and forage preferences in relation to carrying capacity, intake measurement and control/prediction, pasture utilization, protein digestion and metabolism, supplementation…
