Comparisons are drawn between the photoperiodically driven breeding cycles in "long-day" birds and "short-day" mammals, emphasizing the importance of photorefractoriness as a key regulator in the timing processes. It is argued that the two types of breeding cycle may not be so radically different as previously thought and, indeed the cycles may be strictly homologous. Evidence in support of thi...

Bilateral olfactory bulbectomy was carried out on 16 post-pubertal gilts during the winter and spring of 2 consecutive years. Eight bulbectomized gilts in Exp. 1 had 2-7 regular periods of oestrus before becoming anoestrous for greater than 100 days in the summer and autumn. During November, 3 of these gilts were placed with b boar and became oestrous within 9 days, were mated and established n...

Administration of melatonin to advance the breeding season in sheep has been widely used, since this hormone conveys the photoperiodic signal to the reproductive neuroendocrine axis. An increased lambing percentage has been reported following such treatment during anoestrus, which could be mediated through a higher rate of embryonic survival, either by an improvement in luteal function or by a ...

The length of oestrous cycles in a group of mature albino mice has been measured by the technique of daily vaginal smears. A high proportion of mice had prolonged cycles. It was shown that mice housed singly may experience abnormal cycles, the number being least when a wire loop is used for taking the smears. Housing mice in groups of four brought about an immediate cessation of normal cycling ...

AIM Anoestrus is one of the most common functional disorders of the reproductive cycle in buffaloes. In spite of technical advancement, there is no single cure for the management of anoestrus. Therefore, the aim of this study was to find out the efficacy of gonadotropic releasing hormone (GnRH) and metabolic hormone for the management of true anoestrus in buffaloes. MATERIALS AND METHODS The ...

In the study, 1118 Polish Black and White cows from a dairy herd were examined during a three-year period. Three hundred and eighty-eight (34.7%) animals showed no visible oestrus signs until day 60 post-partum. In those cows clinical examinations were performed twice, with a 10 day interval, and blood samples for progesterone analysis were collected simultaneously. Progesterone was measured by...

Serum Ca, P, Mg, Zn, and Cu concentrations in cows affected with reproductive disorders were determined. A possible relation between serum concentrations of these elements and reproductive diseases was evaluated. In total, 109 Holstein cows ageing between 3 and 9 years were investigated. Thirty-six cows showed postpartum anoestrous, fifty-six were repeat breeders, and seventeen cows served as c...

The one-humped camel (Camelus dromedarius) is a seasonal breeder with a relatively short breeding period, when increased ovarian activity is exhibited (Shalash, 1965,1980; Nawito, Shalash, Hoppe ¿St Rakha, 1967 ; Novoa, 1970). In Israel, the normal breeding season occurs from December to early April. Female camels come into heat during this period and exhibit mainly follicular activity; there i...

Submit Manuscript | http://medcraveonline.com Abbreviations: AAU: Addis Ababa University; AFC: Age at First Calving; AFS: Age at First Service; CFT: Complement Fixation Test; CI: Calving Interval; CVMA: College of Veterinary Medicine and Agriculture; NSC: Number of Services per Conception; PGF2α: Prostaglandin F2 Alpha; PPA: Post-Partum Anoestrus; RBPT: Rose Bengal Plate Test; RP: Retained Plac...