T HE ewe is generally considered to be seasonally polyestrual in that she exhibits one or more diestrual cycles during a particular season of the year (Frank and Appelby, 1943). However, estrual activity may vary from the monestrual type exhibited by the wild sheep (Asdell, 1946) to the completely polyestrual type of some breeds in certain locations (Roberts, 1921; Kupfer, 1928; Quinlan and Mar...

This paper reviews current production trends for sheep and beef cattle production in New Zealand and gives some insight into the opportunities for improvement. The New Zealand climate favours pasture growth and this is the key to sheep and beef cattle production with over 95% of the diet being grazed pasture or crop. Exports are the focus of the industry with 92% of sheep meat and 82% of beef e...

Breeding objectives were developed for Targhee sheep under rangeland production conditions. Traits considered were those for which EPD were available from the US National Sheep Improvement Program and included direct and maternal effects on 120-d weaning weight (WW and MM, respectively); yearling weight (YW); yearling fleece weight, fiber diameter, and staple length; and percent lamb crop (PLC)...

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The number of lambs sold per ewe mated in the breeding flock has a considerable impact on sheep operation profitability. This depends primarily on fertility, prolificacy (# of lambs), and lamb survival, mothering ability, milk production of the ewe and lamb growth rate. Optimal reproduction does vary by environment and management system – some sheep operations don’t want a lambing rate over 200...

Abstract. Domestic sheep breeds potential must be preserved in breeding farms, and the main method of improving breed is working with lines. The genetic variability formed by specialized Therefore, further improvement itself should carried out along way its Each lines according to certain characteristics. presence such structures that are not related one ways improve productive biological chara...

Knowledge about genetic markers linked to genes affecting quantitative traits can increase the selection response of animal breeding programs, especially for traits that are difficult to improve when using traditional selection (Meuwissen and Goddard, 1996; Meuwissen and Van Arendonk, 1992). The seasonal breeding pattern that is commonly observed in temperate sheep breeds is a major obstacle to...

Susceptibility to scrapie, a transmissible spongiform encephalopathy in sheep, is modulated by the genetic make-up of the sheep. Scrapie control policies, based on selecting animals of resistant genotype for breeding, have recently been adopted by the Netherlands and other European countries. Here we assess the effectiveness of a breeding programme based on selecting rams of resistant genotype ...

Chlamydophila abortus is one of the most important causative agents of enzootic abortion and other chlamydial infections of sheep and goats. The presence of specific serum antibodies to Chlamydophila abortus was studied in sheep and goats breeding in the Slovak Republic by the complement fixation test. 22,040 sheep and goats were examined during 5 years. Specific anti-Ch. abortus antibodies wer...