Since stress has been shown to influence prolactin release in sheep, the secretion of this hormone during the oestrous cycle of the ewe was re-evaluated. At intervals of two hours, for a total period of 40 hours, blood samples were…
The pattern of luteinizing hormone (LH) and prolactin release following the synchronisation of oestrus with progesterone or SC-9880 was studied. Of the 10 ewes treated with progesterone three did not exhibit oestrus. Where oestrus was synchronised with SC-9880 the preovulatory…
Three experiments were conducted to examine the effects of dilution rates prefreezing and at thawing, pellet volume, and of thawing temperature on the survival and acrosome-morphology of ram spermatozoa. Semen was diluted with a Tris-giucose diluent and frozen in pellet…
Five factorial experiments were conducted to examine the effects of different freezing methods on the survival of ram spermatozoa following the freeze-thawing procedures Semen was frozen in pellet form and in straws on either dry ice or in liquid nitrogen…
Karakul ram lambs were divided into three groups after weaning and treated as follows: Group A: Total isolation; Group B: Contact with ewes until 9 months and then isolated; Group C: Isolated from ewes until 9 months and then allowed…
Directly after calving 62 Bonsmara cows were divided into one of the following groups: Group A served as a control and calves were allowed to remain with the cows and weaned at 7 months. In groups B, C and D…
The incidence of oestrus, ovulation. fertilisation and embryonic mortality were investigated in a series of experiments. In the first experiment, the occurrence of oestrus and ovulation in Africanders and Hereford cows were compared. It was found that Africanders showed oestrus…
Beef production with the Jersey dam as basis. 1. The production potential of jersey cows under extensive conditions During a five year period, an average of 87 Jersey cows and heifers were evaluated for the production of weaners under extensive…
Beef production with the Jersey dam as basis: 2.The production potential of various crossbred Jersey progeny: Two hundred and twenty nine crossbred Jersey calves from Africander, Charolais and Hereford bulls were produced and evaluated as slaughter animals over a four…
Relative economic importance and heritability of certain characteristics of brown Karakul pelts: The economic values of certain characteristics of brown Karakul pelts were compared. In addition these values were considered in relation to certain problems in the breeding of some…
A study has been made of the relation between breed, sex, age and carcass grade of South African cattle and the quality of leather produced from the hides of these animals. From this study it is evident that the hides…
Lamb mortality in the Neudamm Karakul Stud: Lamb mortality in the Neudamm Karakul Stud was recorded and analysed for time and cause of pre- and postnatal losses for all lambs born between April 1969 and December 1970. It was found…
