A study of the duration of oestrus and estrous cycles in mares from Purebred Arabian (PAB) and Shagya-Arabian (ShAB) breeds and the influence of some factors was conducted. The records used for this study were from the breeding registers of the mares from the State Stud farm Kabiuk near Shumen, covering a period of 33 years (1982 to 2015). In the study were included 36 mares with 290 oestruses and 77 estrous cycles from the Purebred Arabian breed and 54 mares with 431 oestruses and 147 estrous cycles from the Shagya-Arabian breed. It was established that the two breeds did not differ reliably by duration of oestrus and length of estrous cycle. With the mares from Purebred Arabian breed the average duration of oestrus is 4,23 ± 0,39 days and the length of the estrous cycle – 24,69 ± 2,29 days, and for the mares of Shagya-Arabian breed – 5,06 ± 0,21 days, 28,36 ± 1, 51 days, respectively. Reliable influence on the duration of oestrus had the year, season, month, month in breeding season, and for the length of the estrous cycle - the year of fertilization.
Duration of oestrus and estrous cycles in mares from purebred arabian and shagya-arabian breeds