Managing The Seasonality of the Horse Life Sciences Research Paper (Research Paper Sample)

Managing The Seasonality of the Horse
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CONTENTPAGE
Introduction3
The endogenous circannual rhythm of reproduction3
External factors entraining the annual reproductive rhythm4
* Photoperiod4
* Temperature5
* Nutrition and body condition Temperature5
Neuroendocrine control of seasonal reproduction6
Conclusion7
References8
Managing The Seasonality of the Horse
Introduction
The horse is one of the species that have seasonability in their reproduction cycle. It experiences its breeding season in spring which is influenced by factors such as increased daylight, temperature and adequate food. The reproductive activity takes place between April and September around the Northern Hemisphere. Therefore, many foals are born on January 1 and the official breeding season occurs between February and June. This results in a similar age for all the foals born in a particular season. Horse breeders end up experiencing a lot of economic pressure in breeding the mares. They have to breed them early enough within the year in order to gain a benefit on the age over the ones given birth to as the year ends. Foals born early enough have a better performance than those born later (Nagy, Guillaume & Daels, 2000).
However, research has proven that the seasonality of the horse can be adjusted by coming up with various induction methods that make the breeding season in horses take place early enough. These methods include comprehending the endogenous circannual rhythm of reproduction, the external factors entraining the annual reproductive rhythm, and using the neuroendocrine control of seasonal reproduction method (Silva, 2016).
The endogenous circannual rhythm of reproduction
Seasonality of reproduction in horses is sometimes caused by the endogenous circannual rhythm of reproduction which is caused by various environmental factors such as temperature, photoperiod, body condition and nutrition. Circannual reproduction cycle has been found to exist in horses. Mares which have been kept in constant long day photoperiod starting at the summer solstice get into anestrus. Likewise, mares which have been kept under short day photoperiod starting at the winter solstice get back to the cyclic ovarian activity (Wilson, 2010). Although doing away with the pineal gland never removes the seasonal reproductivity in horses, their reproductive cycle is not affected by photoperiodic alterations anymore.
External factors entraining the annual reproductive rhythm
The annual reproductive rhythm in horses is affected by various factors such as photoperiod, temperature, nutrition and body condition.
* Photoperiod
Photoperiod of horses is believed to be a very crucial environmental factor which affects the endogenous circannual reproductive cycle. In winter and the beginning of spring, extra light is exposed to horses. This exposure of light stimulates the activity of the ovary, especially in anestrous mares. This, therefore, brings an advancement to the onset of their breeding season. However, the ovarian activity is not always as a result of long days’ exposure (Wilson, 2010).  The stimulatory photoperiod depends on various factors such as the condition of refractoriness to changes in photoperiod, the history of photoperiod and the availability of photosensitive phase in the dark.
Refractoriness is a condition whereby mares maintained in constant lighting conditions still get back to their circannual cycle regardless of their lighting conditions meant to stimulate or inhibit the process. Refractoriness makes the mares unable to respond to any current photoperiod. Therefore, mares maintained under 16L:8D at the beginning of winter or summer still go back to summer anestrous. The way photorefractoriness develops can be extended and reduced by altering photoperiods at various definite levels. For mares, the photorefractoriness is still preventable through reducing any more light exposed to them every day (Silva, 2016).
The ovarian activity is usually induced in anestrous mares which are seasonal through by using the 1- to 2- h light flash not more than 10 hours after darkness begins. This implies that just like the other species which are seasonal, mares also possess a phase which is photosensitive even when there is darkness. Some photoperiod conditions occur naturally. During such conditions, the alteration made in the light and dark phase every day is very gradual. Darkness intensity also experiences a considerable change hence gradually altering each phase’s length (Kirkpatrick & Turner, 2010).
* Temperature
The seasonality in the reproductive activity in horses can also be adjusted through temperature. The activities in reproduction are significantly affected by the range in environmental temperatures, that is, the maximum and minimum temperatures. Cold weather slows down the transition of the spring in a couple of years. Therefore, apart from the photoperiodic activities, nutrition and the management cycle, temperature contributes a lot towards the adjustment of the seasonality of mares (Aurich, 2011). It provides a very good timing in the endogenous circannual rhythm of reproduction.
* Nutrition and body condition
Mares which take supplementary diet such as concentrates tend to experience earlier ovulation just after winter anestrous that those control mares which do not take any supplements. It has also been observed that mares which add on weight at the beginning of spring tend to have a short period of anovulation (Kirkpatrick & Turner, 2010). Taking in high levels of energy makes the first interval of ovulation shorter in transitional mares whose body fat level is low. However, moderate or fat bodied mares do not benefit from it. Poor body condition influences how long each phase of transition takes and the first spontaneous ovulation. It also reduces the administration efficiency of equine pituitary extracted to bring about induction for ovulation to occur.
Apart from the intake of energy, the onset of the breeding system is also affected by the amount of proteins in the diet. Mares which take in a diet with proteins of high quality tend to secrete high amounts of Follicle Stimulating Hormone (FSH). This hormone in return makes them ovulate about three to six weeks before those mares that take in the diet with protein of low quality (Aurich, 2011). Grazing mares on pastures just before they receive their first ovulation also reduces the time they take before the ovulation occurs. Anestrous mares fed on green pastures are likely to receive their faster ovulation earlier tha