- Low sexual urge and fertility in young Angora rams
|Last update: April 3, 2012 10:19:17 AM|
Low sexual urge and fertility in young Angora rams
JHP van der Merwe
IN view of the fact that the Angora goat industry is experiencing such a prosperous period, the increase in numbers of Angora goats is a matter of great importance. Each extra kid that is born and raised represents extra profit for the farmer. Available data shows that the average gross income for .the period 1975/76 was R22,40 per SSU, with a gross margin of R21,37.
Traditionally, the ewe was always blamed for the fertility problem in a flock, and the ram thus escaped the blame through this. It is high time, therefore, that more attention should be given to the potency of the ram.
Infertile rams, or rather rams that are not able to fertilise all the ewes given them successfully, are worthless and belong in die wether flock.
The average Angora farmer uses approximately 3% adult rams and 6% young rams in his flocks. Data obtained from the postal record systems for the period 1975/76 show the kidding percentage to have been about 74%, while 94% of these kids were weaned. Although this can be regarded as reasonably good, there are also a number of cases where the kidding percentage was as low as 50. Management is probably responsible for these low figures in some cases. The contribution of the ram with regard to this aspect is not always fully realised, as a large proportion of these low kidding percentages could be attributed to the impotence of the ram.
In most cases the young Angora ram creates a considerable problem. It is essential that he should be used but often does not make the grade.
Many of the difficulties generally experienced with rams are possibly not as serious in the Angora goat ram as such. However, little research has been done in regard to this aspect on the Angora, and findings obtained from other animal types are applied directly to Angoras at present.
Low fertility and low sexual activity can be divided mainly into four categories, namely:
Anatomical defects can develop as a result of illness, heredity of injury. Examples of anatomical defects are, for example, atrophy of the testis (as a result of injury), hypoplasia (underdevelopment of the testis, which, according to Dr Marius van Tonder of the Regional Veterinary Laboratory at Middelburg, Cape, is a condition generally found among Angora goat rams, and appears to be hereditary as it is often found in specific studs), shortened retractor penis (where the ram cannot move his penis far enough out of the sheath to serve the ewe successfully), etc. Some of these defects are subjectively perceptible, and can therefore be easily selected against.
Pathological causes of low fertility can be ascribed to infection, injury or sexual diseases such as Brucellosis and the infection caused by Actinobacillus seminis. According to Dr Van Tonder, however, both these pathological symptoms occur very seldom in Angora goat rams.
In this article, however, the accent is placed on the physiological and psychological causes for low fertility in Angora goat rams. It must be remembered primarily that the Angora goat ram is an absolutely seasonal breeder. Thus, for example, the ram shows no sexual urge during the spring and early summer. At present it is not altogether clear whether the ram goes into a period of sexual rest as a result of the change of daylight, or whether it is because the ewes are at that time in a sexual rest, and there is therefore no stimulus for the ram.
Very little is known about the hormonal levels in the blood of the Angora goat ram. Cases occur, however, where some clover pastures have had oestrogenic effects on animals. This effect can possibly have an influence on the sexual activity of the rams. It is believed that a good sexual urge is connected with the testosterine-oestrogen proportion in the blood. It is found that the sexual urge in rams varies terrifically. Many rams have a weak libido but will still serve a few ewes. Unfortunately there are rams that will not serve any ewe, and which will even show no interest in a ewe that is on heat.
Some rams do show interest and libido, but do not have the capacity to serve a ewe. Rams with weak covering dexterity are not much use to the farmer as a breeding animal. In many cases, such rams impede the other rams, and really belong in the wether flock.
It is often found that there are rams that dominate the other rams in the flock, and want to serve all the ewes on their own. Such rams are an advantage if hand serving is practised, but they usually fight the other rams wanting to serve the ewes, and may thus injure these other rams and the ewes are not served satisfactorily.
Farmers who observe these problems in their studs should discriminate against them, as such problems as low libido, etc. can possibly become hereditary. Apart from the above, the following can also be causes of low sexual activity and low fertility in young Angora goat rams.
Growth and development of the ram takes place mainly from birth to puberty. During this period the young ram should therefore receive a well-balanced ration, and the following measures should be observed:
Avoid excessive feeding or feed that contains too high a content of carbohydrate during the attainment of puberty and afterwards, as this can give effect to overweight that can have adverse consequences for the ram's ability as a breeding animal. The excessively fat ram's sperm production as well as its sexual urge can be affected. Such rams are usually clumsy, lazy and unfit.
Vitamin A and protein are important for the development of the sexual system. These two components are thus very important to avoid the young ram being incorrectly fed.
It is just as important, however, that the young growing ram is not undernourished. Undernourishment can retard body development, and also delay puberty.
When puberty is reached, and immediately afterwards, is surely the most important psychological period in the young ram. It is at this stage when he becomes aware of his sexual urge. If the young ram is without much physical exercise, and has the company of his fellow rams alone and only feeds, he may easily develop abnormal tendencies. When the active sexual season arrives, these rams will masturbate or mount their companions. In this way many of them develop into homosexuals. Heterosexual contact is thus of great importance.
Exercise is most essential for rams as it keeps them fit and lively, and promotes good sperm production.
It is also important that young rams receive a well-balanced ration that contains sufficient quantities of Vitamin A and protein, especially during the mating season.
Points to be observed when rams are prepared for sale:
Do not put rams on too high a carbohydrate diet. (Beware of obesity)
Ensure that such rams get enough Vitamin A and protein in their diet.
Allow the young rams to run in a small paddock with a few adult ewes.
Give rams enough freedom of movement so that they may get sufficient exercise.
Ensure that the ram delivers enough good quality lively sperm during the mating season.
Make certain that the ram is ready to serve the ewes, by taking him to a ewe on heat during the mating season. If the ram is sold before the mating season, arrange with the buyer to establish this.
The following advice should be of considerable value to the buyer of young rams, and will have an influence on their sexual activity and fertility.
Environment temperature: Change in the environment temperature can often lead to infertility in rams. For example, if rams are moved to an area where the temperature is higher than 35° C, this could lead to infertility in the rams.
Feeding and changes of climate: When the ram is moved from the stud farmer's to the flock farmer's farm it may happen that such a ram is relatively undernourished for a time. It is therefore important that the ram is slowly adjusted to the climate and environment before he is put to the ewes. Try to find out what type of feed the ram had previously received. It is also desirable that the ram be dosed with liquid of the rumen from a slaughtered sheep or goat that was adjusted to the new environment.
When rams are shorn after they have been bought, they must not be placed in the veld on a hot sunny day immediately. Such rams can contract sunburn easily with the accompanying temperature reaction. It is always advisable to provide shade in the camps where ewes are mated.
Prevent injuries to the sexual parts of the rams when they are being transported.
Inoculate against diseases: Inoculation against bluetongue, Rift Valley fever, Wesselsbron, etc., where use is made of active vaccine, usually causes a fever reaction 4 to 8 days after inoculation. Such fever reaction has a most harmful effect on the spermatogenesis and can even lead to its suspension. In cases where the sperm has died off, it takes up to seven weeks for new sperm to be formed. A further two weeks is necessary before normal conception can take place. Such an Angora goat ram can only become normally fertile again after 10 weeks. It appears most advantageous, therefore, to inoculate Angora goats against such diseases before the end of November each year.
Although rams are not overworked easily, it can happen when young rams with a good libido must serve a large number of ewes. It even occurs that such rams suffer a permanent setback.
Many farmers are under the impression that they can put 3% of rams among the ewes without ensuring that all the rams are serving the ewes. Consequently it happens that the rams become overworked. The solution to this problem, naturally, is the application of hand serving. Then the farmer can exercise control himself on how many ewes can be served daily by a ram, and at the same time he gets an indication of the potency of his rams.
Angora goat and mohair journal 19 (1)