REPRODUCTIVE PARAMETERS OF THOROUGHBRED MARES IN CROATIA

For the purpose of gaining better cognition on Thoroughbred breeding in Croatia, reproductive parameters of 87 Thoroughbred mares were analyzed. An average age of the first covering and foaling were 5.9 and 6.6 years, respectively. The average gestation length was 341.1 days and the most frequent foaling period (20.2% of foalings) was recorded between 336 to 340 days of gestation. Prolonged gestation period (p<0.05) was determined in colts. The gestation length was the longest in January (344.4 days) and the shortest in July (324.0 days). Between the gestation length and the age of the mare no significant correlation was found. There was a trend of foaling rate decreasing in mares older than 11 years. The highest number of successively registered foalings with 10 live born foals was observed on 2 individual samples. The greatest number of foalings occurred in April (30.9%), whilst there was no foaling in October. The genders were 50.6% male and 49.4% female foals. The incidence of abortions was 7.3%. Although indicators point to the breeding strategy heading towards the right direction, by educating the owners and with frequent veterinary supervision, especially for twin reduction, the reproductive performance could be enhanced

Primjena asistirane reprodukcije u govedarstvu

More than five decades of research in reproductive biology have resulting in the development of biotechnologies in the cattle industry to increase efficiency in beef and dairy production systems. These technologies are related to gamete and embryo manipulation aimed at improving fertility and genetic progress. The application of assisted reproductive technology in stockbreeding has tremendously altered the rate of genetic improvement in breeding programmes and strategies. Artificial insemination, embryo transfer and in vitro embryo production are technologies systematically applied in breeding programs around the world. They enable rapid genetic progress, shortening of the generation interval, control of disease transmission and reduction of production costs. Worldwide, artificial insemination has been the most efficient and useful way to improve the genetic quality of the herd. Over a period of thirty years, embryo transfer has become an internationally accepted technology with over 500, 000 in vivo produced embryos per year. The recommended handling procedures of the International Embryo Transfer Society enable the safe export of in vivo derived embryos, without the risk of disease transmission. Approximately 15% of embryos produced annually are produced by in vitro technology. This technology enables embryo production from cows of high genetic merit that cannot produce offspring by conventional reproduction. Improvements in OPU/IVF programs would have a great impact on the cattle industry and could replace the traditional MOET programs in the near future. Furthermore, they are important for the development and operation of a gene bank for the cryoconservation of animal genetic resources, to preserve indigenous and endangered breeds of cattle. In addition to genetic progress, the application of these biotechnologies in animal breeding permits high quality breeding stock to be available on the market and enables the application of advanced technologies. Semen and embryo sexing allows for identification and selection of sex, which can assist in the more efficient management of resources. Cloning and transgenesis have great potential in the cattle industry, though due to their low efficiency and high costs, these technologies are predominantly applied in experimental settings and the production of pharmaceuticals