Profit rate for a meat production enterprise can be decomposed into the unit price for meat and herd efficiency. Optimal slaughter mass maximizes herd efficiency which, at its maximum, can be expressed in terms of a product of…
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…
Feeder- breeder dimorphism is advantageous when large offspring for slaughter is obtained from small breeding animals. The effect of feeder- breeder dimorphism on herd efficiency is evaluated for terminal crossbreeding and growth modification by biotechnological or dietary means. Selection criteria…
Higher reproduction and lower replacement rates lead to a higher proportion of terminally crossbred offspring to sell. Substantial improvement in herd efficiency can be achieved by improvement in the ratio of replacement rate to reproduction rate by selection or crossbreeding.…
Carcasses of 122 ram lambs born from Finnsheep X Merino (FM) and Merino (ME) as dam lines, crossed with the Ile de France (IF), SA Mutton Merino (SAMM), Dohne Merino (DM), FM and Merino as sire lines were evaluated for…
The seasonal growth pattern and dry matter (DM) yield of bana grass (Pennisetum purpureum x P. americanum) was compared with that of kikuyu (P. clandestinum) under irrigation. In addition, the yield and chemical composition of bana grass at different stages…
Bana grass (Pennisetum purpureum x P. amerieanum) was compared with kikuyu (P. clandestinum) and forage sorghum (Sorghum bicolor) with respect to quality of samples ;elected by four oesophageally fistulated steers. Hand-cut samples of the three forages were also compared…
The experiment was conducted (i) to compare the chemical and physical composition of grain sorghum produced at different locations, (ii) to compare the digestible energy (DE) content of different grain sorghum cultivars produced at different locations, and (iii) to evaluate…
This study was undertaken to investigate the genetic stability of an unselected Control Group of South African Merino sheep and genetic change in a flock selected for increased clean fleece mass (Selection Group) under the same environmental conditions. Data regarding…
African Mutton Merino ewes as supplementary feed during late pregnancy and lactation, while grazing wheat stubble at 2 ewes/ha during 1986 and 1987. Blood glucose, urea, calcium, magnesium and zinc levels of the ewes were monitored in 1986 only. Ewes…
Data consisting of 445 calving records from Bonsmara breeding females were studied in order to establish relationships between body mass and conception. Significant relationships between body mass at the start of the mating period and percentage conception were established by…
Data from 267 individuals were used to. investigate factors influencing 13 linear type traits (scored on a 1-50 point scale) in progeny of a Merino flock subjected to 20 years of selection for increased clean fleece mass (Selection Group, 116…
Heritability estimates were obtained by using a unitrait derivative-free animal model REML programme. Estimates of heritability for curl type (h 2 = 0.46) and pattern score (h 2 = 0.27) followed expectations as derived from literature. The estimate for hair…
Irrigated tall fescue (Festuca arundinacea: Schreb) was evaluated over four seasons, in the spring and autumn, and was able to maintain a milk production of 15.5 kg FCM/d for medium-sized(550 kg) Friesian cows in mid-lactation, under a lax grazing programme.…
Dairy cattle semen imported from January 1979 to June 1989 consisted of 72% Holstein-Friesian, 13.6% Jersey, 11.5% Ayrshire and 2.8% Guernsey semen. There has been a significant increase in the importation of Holstein-Friesian semen and, to a lesser extent, in…
Restricted maximum likelihood (REML) is widely regarded as the preferred procedure for estimating variance components in animal breeding problems. The size of the coefficient matrix, however, often leads to computational difficulties and many simplified algorithms, including diagonalization, have been proposed.…
DNA polymorphisms that can be detected by restriction endonucleases are valuable in population and linkage studies. In this manuscript we have reported on the occurrence of DNA polymorphisms in a defined region of the bovine thyroglobulin gene. We have shown…
Three ruminally cannulated mature steers were fed, in a crossover design, diets with concentrate to roughage (C: R) ratios of 80: 20, 55: 45 and 30: 70, twice a day (09: 00 and 15: 30) in a predetermined feed intake…
A total of 108 medium frame weaner steers, divided into 9 groups of 12 each with mean group masses of 200 kg, were used to determine the effect of three concentrate to roughage (C: R) ratios (80: 20, 55: 45,…
The effect of diets with three divergent concentrate to roughage (C : R) ratios (80: 20, 55: 45 and 30: 70), fed at three feed intake levels (ad libitum, 90% ad libitum and 80% ad libitum), on carcass composition…
