Artifical Insemination of Dairy Cattle in Queensland. Influence of Certain Aspects of Oestrus on Fertility
نویسنده
چکیده
Large-scale artificial insemination services in Queensland date from 1955. In that year a bull-proving project was inaugurated for the purpose of locating dairy sires of outstanding genetic merit from Queensland studs. The project requires the artificial insemination of at least 1,000 cows each year in the Nambour region of south-east Queensland. In September, 1957, an artificial insemination centre was opened on the Atherton Tableland in north Queensland. Fertility results to date have been quite satisfactory and far exceed the level of natural fertility. An attempt is being made to study the various factors influencing fertility under artificial insemination conditions. In particular, the problem of anoestrus and the phenomenon of oestrous cycles atypical in duration are under consideration.
منابع مشابه
Physiological aspects of reproduction and fertility in dairy cows
Reproductive efficiency is an important aspect of dairy cattle production. To improve it in high yielding dairy cattle, a thorough understanding of the physiology of fertility and the reproductive physiological implications of the increasing metabolic demands associated with increasing production levels is essential. In this respect, the present paper focuses on the neuro-endocrine regulation o...
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Artificial insemination was used in an attempt to breed three groups of Brahman cross cows on two properties in north Queensland. On one property the attempt was abandoned due to low incidence of detected oestrus in lactating cows. On the other property calving rates following insemination were 20.8% and 16.4% over two years. Vibriosis was one cause of low fertility. Semen was collected satisfa...
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Six priming doses of 40 mg progesterone at two day intervals followed by 1,000 I.U. P.M.S. were superior to two priming doses plus P.M.S. in inducing oestrus. At the first insemination after induction of oestrus, fertility was normal in animals which received two doses, but depressed in those which received six doses of progesterone. An injection of 40 mg of progesterone after the injection of ...
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The pregnancy rate resulting from matings at a single oestrus in beef cattle averages 70% for natural mating (Turman, Laster, Renbarger & Stephens, 1971) and 60% for artificial insemination (Laster, Glimp & Gregory, 1972). The sources and causes of low pregnancy rates have not been defined, but might include variation in time of ovulation relative to deposition of spermatozoa in the female repr...
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