Clinical and endocrine aspects of the oestrous cycle in donkeys (Equus asinus)

Henry, M.; Figueiredo, A.E.; Palhares, M.S.; Coryn, M.; Henry, M; Figueiredo, A.E; Palhares, M.S; Coryn, M

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Clinical and endocrine aspects of the oestrous cycle in donkeys (Equus asinus)

Henry, M.; Figueiredo, A.E.; Palhares, M.S.; Coryn, M.

Journal of Reproduction and Fertility. Supplement 35: 297-303

1987

ISSN/ISBN: 0449-3087

PMID: 3479584

Document Number: 304478

Oestrous behaviour and occurrence of ovulation were studied in 13 female asses (3-18 yr of age) during a 15-month period. Teasing was performed daily and follicular growth, ovulation and changes of the genitalia were checked every other day by rectal palpation during dioestrus or the anovulatory season or daily during oestrus and when a follicle 3 cm in diameter was present. Plasma oestrogens and progesterone concentrations were measured by radioimmunoassay. Of the 13 females, 6 showed a typical seasonal ovarian activity, 1 stopped cycling only at the end of the experiment, 2 ovulated regularly and 4 did not cycle. Mean length of the anovulatory season in the 6 jennies with seasonal cyclic ovarian activity was 166.3+or-63.2 days (74-263 days). Irregular oestrous periods were detected during the anovulatory season of these jennies. Irregular signs of oestrus and follicular growth were detected in the 4 jennies which remained acyclic during the whole experiment. Mean length of the ovulatory season was 197.8+or-63.4 days (102-291 days). Overall mean lengths for the oestrous cycle and dioestrous and oestrous periods were 25.9+or-2.7 (n = 74), 18.2+or-2.3 (n = 70) and 7.9+or-2.5 (n = 79) days resp. Ovulatory oestrous periods tended to be longer at the start and end of the season than during the summer months. Dioestrous length was not affected by season. Ovulation occurred near the end of oestrus and was more frequent from the left (61%, n = 77) than from the right (39%, n = 49) ovary (P<0.02). The incidence of single, double, triple and quadruple ovulations was 62.8 (n = 54), 25.5 (n = 22), 10.5 (n = 9) and 1.1% (n = 1) resp. One period of spontaneous prolongation of luteal activity was detected and it lasted for 80 days. Progesterone concentration was <1 ng/ml from 1.75+or-0.88 (n = 8) days before the onset of oestrous behaviour up to the day after ovulation. Corpus luteum lifespan was 15.7+or-2.1 days (range 13-20 days, n = 9). Oestrogen concentration peaked 1-3 days before ovulation, and reached dioestrous values up to 3 days after ovulation.

Clinical and endocrine aspects of the oestrous cycle in donkeys (Equus asinus)

Henry, M.; Figueiredo, A.E.; Palhares, M.S.; Coryn, M.

Journal of Reproduction and Fertility. Supplement 35: 297-303

1987

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