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| | '''[[Female Seasonality - Donkey|Seasonality]] | | '''[[Female Seasonality - Donkey|Seasonality]] |
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| | + | '''[[Oestrus Cycle - Donkey|Oestrous cycle]] |
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| − | ==Oestrous cycle==
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| − | [[Image:Mating behaviour jenny donkey.jpg|right|thumb|300px|<small><center>Mating behaviour, showing typical ‘yawning’ or ‘mouth clapping’ of the oestrous female during mating.(Image courtesy of [http://drupal.thedonkeysanctuary.org.uk The Donkey Sanctuary])</center></small>]]
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| − | [[Image:Table 1 oestrus cycle donkey.jpg|right|thumb|400px|<small><center>(Image courtesy of [http://drupal.thedonkeysanctuary.org.uk The Donkey Sanctuary])</center></small>]]
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| − | <u>The oestrous cycle is slightly longer than that of the mare and normally lasts 23 to 24 days, but can range from 13 to 31 days</u> (Table 1). '''Oestrus lasts 3 to 15 days'''. Signs of oestrus include '''tail raising, urination stance, winking of
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| − | the clitoris, ears back, mounting other females, standing to be mounted''' and''' vulvar oedema'''. These signs intensify in the presence of the male and are accompanied by a '''yawning reflex''' with the neck extended (jaws clamping, yawning) (Henry ''et al'', 1987; Fielding, 1988; Tibary and Bakkoury, 1994).
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| − | '''Follicular dominance''' is established at a diameter of about '''25 mm'''. Most dominant follicles are about 27 mm in diameter at the onset of oestrus. Follicular growth averages 2.7 mm per day (Dadarwal et al, 2004). <u>Ovulation takes place during the last 24 hours of heat.</u>
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| − | Behavioural oestrus persists a few hours (0.7-0.8 days) after ovulation (Vandeplassche ''et al'', 1981, Henry ''et al'', 1987). The average size of the preovulatory follicle may be breed-dependent. It is 30 to 33 mm in the Poitou and 35 to 40 (39.4 mm) in the Pega and Mammoth (Lun ''et al'', 1998). North African jennies may ovulate at a smaller size (32 mm).
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| − | An incidence of '''double, triple and quadruple ovulations''' of respectively 25.5%, 10.5% and 1.1% has been reported in some breeds. The incidence of multiple ovulations generally ranges from 5 to 32 % (Vandeplassche ''et al'', 1981; Ginther ''et al'', 1987; Meira ''et al'', 1995; Blanchard and Taylor, 2005). Double ovulation incidence can be as high as 37%. Incidence of multiple ovulations can reach 61% in mammoth jennies (Blanchard ''et al'', 1999). The majority (75%) of double ovulations are asynchronous with the interval between ovulations ranging from one to four days in general and up to eleven days in some instances. The incidence of double ovulations and twinning is extremely low in the North African donkey.
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| − | In general, jennies are in oestrus until occurrence of the second ovulation (Vandeplassche ''et al'', 1981). Twin births are rare, but have been reported in higher numbers in the Mammoth jenny and in the dairy breed Ragusana in Sicily (Mancuso ''et al'', 2004). The approach to twin management should be similar to that used in mares.
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| − | The '''inter-ovulatory period''' is significantly longer in jennies than in mares (Vandeplassche ''et al'', 1981; Ginther ''et al'', 1987; Meira ''et al'', 1995). The average life span of the ''corpus luteum'' is 15 to 20 days (19.3 ±0.6 in standard jennies (Vandeplassche ''et al'', 1981) and 17.4 ± 2.6 days in mammoth jennies (Blanchard ''et al'', 1999). The inter-ovulatory period is 24.9 ± 0.7 days for standard and 23.3 ± 2.6 days for mammoth jennies (Vandeplassche ''et al'', 1981; Blanchard ''et al'', 1999).
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| − | The ultrasonographic characteristics of the uterus at different phases of the oestrus cycle are similar to those described for the mare (Lemma ''et al'', 2006).
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| − | {{toplink
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| − | |linkpage =Female Reproduction - Donkey
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| − | |linktext =Female Reproduction - Donkey
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| − | [[Category:Donkey]]
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| − | {{toplink
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| − | |linkpage = Sponsors
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| − | |linktext = This page was sponsored and content provided by ''THE DONKEY SANCTUARY''
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| | ==Pregnancy== | | ==Pregnancy== |
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