The tick burdens of 115 Merino sheep, slaughtered over a period of 15 consecutive months on a farm in the north-eastern Orange Free State, were determined. A total of 7 ixodid and 1 argasid tick species were recovered and the seasonal abundances of Boophilus decoloratus, Hyalomma marginatum rufipes, Margaropus winthemi and Rhipicephalus evertsi evertsi were determined. One hundred and forty-nin...

Forty-two 7-mo-old Australian Merino wethers were used in a 50-d trial to investigate the effects of Se and vitamin E on the performance and physiological responses of heat-stressed sheep. Sheep were exposed to thermoneutral conditions (maximum = 24°C and minimum = 20°C) for 28 d followed by heat (maximum = 38°C and minimum = 28°C) for 22 d. Hot conditions were imposed between 0700 and 1800 h. ...

Salinomycin is a monocarboxylic polyether ionophore with antimicrobial properties. It is a dietaryadditive used as a growth promoter for ruminants and as a coccidiostat in chickens. The mechanism of actionof ionophores at the cellular level is to selectively bind certain ions creating intra and extracellularbiochemical disturbances. Clinical signs of ionophore intoxication are non specific and ...

Myostatin or growth and differentiation factor 8 (GDF8), has been known as the factor causing double muscling phenotypes in which a series of mutations make the myostatin protein inactive, hence disabling it to regulate the deposition of muscle fibre. This phenotype happens with high frequency in a breed of sheep known as the Texel. Quantitative trait loci (QTL) studies show that a portion of t...