Changes

== Female Threshold Body Size ==

== Female Threshold Body Size ==

* Autumn born lambs do not reach puberty until 10-12 moths of age.  

* Autumn born lambs do not reach puberty until 10-12 moths of age.  

* This is because, seasonal cues (long days of spring/summer) delay reproductive cyclicity.

* This is because, seasonal cues (long days of spring/summer) delay reproductive cyclicity.

* Thus, [[Reproductive_Behaviour_-_Oestrus_Behaviour_- Anatomy & Physiology|oestrus]] in both spring and autumn born lambs is synchronised.

* Thus, [[Oestrus Behaviour - Anatomy & Physiology|oestrus]] in both spring and autumn born lambs is synchronised.

* This maximizes the chance that all ewes become pregnant in the fall and give birth in the spring when nutritional and environmental conditions are favourable.

* This maximizes the chance that all ewes become pregnant in the fall and give birth in the spring when nutritional and environmental conditions are favourable.

* An adequate degree of nutrition ('fatness') is required before photoperiod can exert an effect.

* An adequate degree of nutrition ('fatness') is required before photoperiod can exert an effect.

* Onset of puberty occurs in January-February in the Northern Hemisphere, where there is increasing day length.

* Onset of puberty occurs in January-February in the Northern Hemisphere, where there is increasing day length.

* Queens born in February-March do not reach puberty until the following spring.

* Queens born in February-March do not reach puberty until the following spring.

* Queens born in summer/autumn generally display their first [[Reproductive_Behaviour_-_Oestrus_Behaviour_- Anatomy & Physiology|oestrus]] the following January.

* Queens born in summer/autumn generally display their first [[Oestrus Behaviour - Anatomy & Physiology|oestrus]] the following January.

* Before this can have effect, there must be adequate nutrition and growth.

* Before this can have effect, there must be adequate nutrition and growth.

== Environmental and Social Conditions ==

== Environmental and Social Conditions ==

* [[Attractivity Behaviour - Anatomy & Physiology#Pheromones|Pheromonal]] substances in the [[Normal_Composition_of_Urine_- Anatomy & Physiology|urine]] act as a stimulus to enhance the onset of puberty.

* [[Attractivity Behaviour - Anatomy & Physiology#Pheromones|Pheromonal]] substances in the [[Urine Normal Composition|urine]] act as a stimulus to enhance the onset of puberty.

* Females reaching puberty in the presence of a male (producing the pheromones) have a greater opportunity of becoming pregnant.

* Females reaching puberty in the presence of a male (producing the pheromones) have a greater opportunity of becoming pregnant.

* Pubertal onset cannot be accelerated using [[Attractivity Behaviour - Anatomy & Physiology#Pheromones|pheromones]] in animals that have not achieved the appropriate metabolic body size to trigger [[Hypothalamus_- Anatomy & Physiology|hypothalamic]] responsiveness to Oestradiol (oestrogen).

* Pubertal onset cannot be accelerated using [[Attractivity Behaviour - Anatomy & Physiology#Pheromones|pheromones]] in animals that have not achieved the appropriate metabolic body size to trigger [[Hypothalamus_- Anatomy & Physiology|hypothalamic]] responsiveness to Oestradiol (oestrogen).

* The [[Hypothalamus_- Anatomy & Physiology|hypothalamus]] then gains the ability to produce high frequency and high amplitude pulses of GnRH at an earlier age.

* The [[Hypothalamus_- Anatomy & Physiology|hypothalamus]] then gains the ability to produce high frequency and high amplitude pulses of GnRH at an earlier age.

[[Category:Reproductive System]]

[[Category:Puberty]]

[[Category:Bullet Points]]