Low-protein teff hay was supplemented with 3% urea and 6% starch to promote growth of the amylolytic bacteria, which liberate branched chain amino acids in the rumen upon lysis. These serve as a source of branched chain volatile fatty acids…
The culture outflow-rate from a specially designed pH-auxostat continuous culture system can be used to calculate the specific growth rates of different bacterial species on suspensions of cellulose or other insoluble substrates. Provided a constant concentration of substrate is maintained…
Nylon bags of different mesh size (5-53 μm), containing ground lucerne, were incubated in the rumen of sheep fed lucerne hay. Counts of total culturable, proteolytic and cellulolytic bacteria were performed on the bag contents after 16 h of incubation…
Different forages were analyzed after in vitro fermentation for amino acid and metabolizable energy content, in order to evaluate their potential as ruminant feeds. Least-cost formulations of supplemental by-pass proteins provide the balance of amino acids required for duodenal amino…
The protein degradability of 13 South African ruminant feed protein sources were determined by the artificial fibre bag technique. Three sheep fed ad lib. on a basal diet of lucerne hay were used. Estimates obtained by two methods of calculation…
The digestibility of organic matter (DOM) of material selected by cattle, Boer goats, Dorper and Merino sheep on natural Karoo pasture was investigated. A highly significant difference (P ≤ 0,01) in DOM selected between years, with an interclass (animal types)…
Some non-genetic sources of variation In milk production of registered Friesland cows. The effect of year, season and month of calving, herd, lactation number, and their first-order interactions with each other, as well as age at calving and calving interval,…
Semen was collected weekly throughout the year from three Boer goat rams with the aid of the artificial vagina and from two Angora and two Boer goat rams by means of electrical stimulation, to determine seasonal variation in semen quality…
Plasma LH and progesterone levels were measured daily from the sixth to the fifteenth day of the oestrous cycle in Friesland cows during December (summer) of one year, and April/May (autumn), June/July (winter) and September (spring) of the following year…
A total of 828 crossbred beef and dual-purpose type cows were allocated to three herds which were bred either artificially, artificially followed by natural service or by natural service only. Conception rates were 72,9; 88,2 and 94,3 % respectively. The…
Two groups of nine animals each, were fed either a conventional diet based on ground maize or whole maize and roughage protein - additive - mineral pellets in a cafeteria system. Both groups were fed ad libitum for a period…
Modifications to a simple and rapid technique for the insertion of rumen cannulae in sheep are described. The modified technique, executed in three phases, was developed to facilitate the fistulation and insertion of rumen cannulae in pregnant ewes, especially during…
The last 20 years of research in South Africa on feeding standards is reviewed. A major contribution to quantitating energy requirements for growth has been the advent of growth-curve analysis which enable accurate pattern description of genotype and dietary responses…
Animal breeding research in South Africa. During the 1979/80 financial year R310 million or 0,64 % of the GNP was spent on research. Of this amount 89,28 % was spent on research in the natural sciences and 10,72 % on…
National planning and coordination of animal research in South Africa. The Department of Agriculture makes the biggest financial inputs into animal research in South Africa. It is therefore appropriate to examine the organization and objective management system of the Department…
Embryo micromanipulation techniques and their potential genetic impact in dairy cattle are discussed. In addition, some aspects of gene transfer are mentioned. Only the technique of splitting bovine embryos and the subsequent transfer of half-embryos has reached a stage which…
Nutrition research with grazing ruminants. Native pasture is still the main source of feed supply for the sheep and beef cattle industries. Apparently an inadequate intake of digestible nutrients puts a limitation on animal production. Due to the seasonal pattern…
