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Puberty Defining - Anatomy & Physiology (view source)
Revision as of 14:45, 4 September 2008
, 14:45, 4 September 2008→Female
== Age at First Oestrus ==
== Age at First Oestrus ==
* The age that the female becomes sexually receptive and displays the first oestrus.
* Easy to determine because females show outward behavioural signs of sexual receptivity, especially in the presence of a male.
* The first ovulation is usually not accompanied by behavioural oestrus in heifers and ewes and is hence termed 'silent ovulation'. Thus, the age at first oestrus may not accurately reflect acquisition of puberty.
== Age at First Ovulation ==
== Age at First Ovulation ==
* The age at which ovulation first occurs.
* Manual or visual validation is required. This can be accomplished by palpation of the overy per rectum in animals that are large enough to permit insertion of a hand/arm into the rectum (cow and camelids).
* Ultrasound can be used most successfully in the mare to determine ovarian status.
* When ovulation has occured, a soft depression on the surface of the ovary can be palpated.
* In smaller animals (sow, ewe, bitch, queen) surgical procedures are necessary to allow visualisation of the ovary in order to determine ovulation. In addition laparoscopic observation can be used to determine when ovulation occurs.
* All techniques require frequent observation of the ovary, so although age at ovulation is a good criterion for puberty, it is difficult to determine.
== Age at which the Female can Support Pregnancy without Deleterious Effects ==
== Age at which the Female can Support Pregnancy without Deleterious Effects ==
* Most practical definition in all domestic animals.
* Acquisition of a threshold body size is important in controlling onset of puberty.
* Energy requirements for follicular development and ovulation are small, however the metabolic cost of pregnancy and lactation are high so the female must reach a 'metabolic threshold' before puberty can occur.