Abstract
The purpose of the present study was to determine the onset of breeding season, the occurrence of silent and true heats and the duration of estrus in female Markhoz goats of the Kurdistan province in Iran. Ten, 3 years-old Markhoz does with an average weight of 34.05±2.62 kg and with one kidding record, were used. The goats were maintained in an open barn under constant nutritional levels and natural photoperiod. One aproned buck was used twice a day every 12 h to detect estrus from mid August to early January. For the determination of the onset of reproductive activity as well as occurrence of silent heat, blood samples were collected every 10 days, from the beginning of the experiment. After 2 nd standing heat, blood samples were obtained twice a week in order to assess luteal activity and the length of estrous cycles. In this study, estrous behavior was observed including sniffing, vocal exchange, following courtship, flehman, standing heat and mounting. The results of the progesterone assay indicated that in this goat silent heats occur mostly in the early breeding season. The first standing heat was observed in mid-October which was considered as the onset of the breeding season. Duration of the estrous cycle and estrus was recorded as being 20.93±1.56 days and 38.86±15.19 h, respectively. The correlation coefficient between length of daylight and occurrence of estrus was negative (r = -0.470) but not significant (p>0.05). The data showed that there was no significant effect of body weight on estrous cycles (first, second and third) and estrous periods (first, second, third and fourth). Progesterone levels were not significantly different in the first, second and third estrous cycles at days 0, 4, 10, 12, 14 and 19. The results of progesterone assay during the estrous cycle indicate that follicular and luteal phases last 4-5 and 14-15 days, respectively and the concentration of serum progesterone in these phases was 0.88±0.08 and 7.44±0.26 ng/ml, respectively. The study concluded that Markhoz does could be considered as a breed with a short breeding season and an optimal estrous activity in autumn. (Key Words : Breeding Season, Estrous Cycle, Silent Heat, Progesterone, Markhoz Goat)
Highlights
Today around 25,000 Markhoz (Angora) goats are raised in Kurdistan province of Iran and produce 20 ton of mohair annually
This study of Markhoz goat does reveals a breeding season commencing in mid-October
The present study has shown that silent heats occurs in Markhoz does around the onset of the breeding season as reported for other breeds (Thompson et al, 1983)
Summary
Today around 25,000 Markhoz (Angora) goats are raised in Kurdistan province of Iran and produce 20 ton of mohair annually. The mohair obtained from these animals has important cultural role and uses for making of local clothes in Kurdistan and they provide a major source of red meat in Iran (102,000 ton per year). These small ruminants are easy to handle, withstand harsh conditions (Zarkawi and Soukouti, 2001) and are found in many arid and semi-arid areas where they are used as multipurpose animals for the production of milk, meat, hair and hide (Amoah et al, 1996; Rashidi, 2000; Zarkawi and Al-Masri, 2002). Other environmental stimuli, such as availability of food and social interactions (Restall, 1992; Restall et al, 1995), should not be discarded as potential regulators of seasonal reproduction
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