Observation of farm animals on heat
Afrikaans | Xhosa
- Young ewes reach puberty between 7 and 12 months of age. Differences occur between breeds, and environmental conditions like feeding and care also influence the age that animals reach puberty.
- Ruttishness indicates puberty.
- Young ewes that reach puberty are not necessarily suitable for breeding immediately, since they are not yet fully grown.
- Ewes should reach a body mass of at least about 40 kg or two-thirds of adult mass before they are paired for the first time. The development of ewes and their reproductive potential can be impaired if they are used for breeding at too early an age.
- Animals pair during a period of ruttishness. This is followed by a period of breeding rest, during which pairing does not take place.
- The periods of ruttishness and breeding rest follow a cycle that is controlled by hormones. The cycle is repeated every 14 to 19 days, with an average of 17 days in the case of sheep.
- Ruttishness lasts for an average of 27 hours but can be as short as 3 hours in the case of young ewes.
- Under favourable conditions, breeds like the Merino, Dohné Merino, SA Meat Merino and Dorper become ruttish throughout the year, although sexual activity is generally seasonal.
- Sexual activity is determined largely by the length of daylight. When the days become shorter in autumn, sexual activity increases. At the start of summer, when days become longer, sexual activity is at its lowest. A period of breeding rest may then occur, during which ruttishness does not take place.
- The ruttishness cycle stops during pregnancy.
- Feeding and the general care of sheep strongly influence the sexual cycle and the seasonal occurrence of sexual activity.
- Rams can produce fertile seed from 6 to 8 months of age but are generally not used for servicing before 18 to 24 months of age.
- The sexual activity of rams is not as seasonal as that of ewes, although it is at its highest in autumn. High temperatures (above 27°C) can be detrimental to the quality of semen.
Observation of heat
- Ruttishness is not as noticeable in ewes as in cows.
- Ewes show a restlessness.
- A tremendous shaking of the tail is characteristic.
- The vulva may be slightly swollen.
- The best indicator of ruttishness is the presence of rams among ewes.
- Ewes on heat seek out rams.
- Ewes on heat usually stay close to rams and repeatedly rub their necks or bodies against those of the rams.
- The surest indication of ruttishness in ewes is that they stand still when a ram mounts them.
- Teasers or rams with aprons, which prevent penetration, can be used to identify ewes on heat.
- If constant observation is not possible, markers on the chests of rams can be used to mark ruttish ewes. A mixture of ochre dye and margarine can be rubbed on the rams chests if marking equipment is not available.
Various methods of servicing are used:
- Group or flock pairing, where either one or more rams are used to service ewes.
- Manual pairing, where ruttish ewes are generally identified by teasers and then paired individually with a specific ram.
- Artificial insemination, where ruttish ewes are inseminated with seed.
Irrespective of the method used, flock management should be aimed at increasing sexual activity and maintaining rams and ewes in good condition to ensure successful
- Rams should be provided with supplementary feed before and after servicing.
- Ewes should be provided with stimulants from three weeks before servicing to a month after servicing, taking into account the condition of the ewes. The animals should not be fattened too much.
- Rams should be tested for fertility and servicing ability before pairing and they should be exercised for fitness (walked 1 to 2 km every day at a fast pace).
- Contact between rams and ewes before servicing should be avoided.
- Teasers can be placed with ewes two weeks before servicing to stimulate sexual activity.
- Treatment against external and internal parasites and immunisation should be completed a month to two weeks before servicing.
- Ewes with wool growth of longer than six months should be crutched.
- Enough rams should be used in flock pairing (3 to 4%).
- Young ewes should preferably be paired separately.
- Pairing should be continued for at least two ruttishness cycles, i.e. 34 days.
- Small camps with sufficient grazing or feed, water and shade should be used.
- The ewes should be kept calm for four weeks after servicing.
- Heifers reach puberty between 6 and 15 months of age. Differences occur between breeds, and feeding also influences the growth and development of the animals.
- Heifers should be used for breeding preferably from 18 to 24 months of age. Decreased fertility and milk yield can be expected in heifers that are serviced as soon as they reach puberty, since this impairs growth and development.
- Ruttishness indicates puberty.
- Cows have a ruttishness cycle of 21 days, i.e. cows should come on heat every 21 days, although this can vary from 18 to 23 days.
- Ruttishness can last between 3 to 24 hours, with an average of 16 hours. Pairing can take place in this period.
- Pairing usually does not take place in the breeding rest period, which lasts about 20 days.
- The heat cycle can be interrupted by pregnancy and sickness.
- The heat cycle starts again about two months after calving.
- The sexual cycle of cows is not seasonal and can last throughout the year. A rest period can occur in winter and spring if feeding and weather conditions are unfavourable. This occurs more generally in heifers.
Observation of heat
- Rutthishness in cows is usually very noticeable.
- Restlessness is one of the first symptoms.
- The cows low as if looking for their calves.
- Ruttish cows sometimes separate themselves from the other cows and wander away.
- The cows urinate little by little and sniff the air.
- The ears move actively and the eyes have a wild expression.
- Ruttish cows lick other cows, play with their heads and rest their heads on other cows.
- The cows try to mount other cows and let other cows mount them.
- The vulvas are swollen and slime sometimes hangs from the vulvas. The tails hang next to the vulvas and are slightly lifted.
Artifical insemination is commonly used as the servicing method, especially in milkers. Group pairing by one or more bulls per herd is commonly used in beef cattle.
The physical health and good sexual activity of bulls and cows are necessary for successfull servicing:
- Bulls and cows should be in good condition before servicing.
- Bulls should be tested for fertility and servicing ability.
- Treatment against external and internal parasites should take place before servicing.
- In the case of beef cattle, every bull should preferably be put in a camp with his own herd of cows (30 to 40 cows per bull).
- Bulls should be removed from a herd of cows after two to three months.
- In the case of dairy cattle, ruttish cows are taken to a bull or artificial insemination is applied.
- Ruttishness lasts for an average of 21 days.
- Sows remain ruttish for two to three days.
- Ruttishness is determined by testing the sows for the "standing reflex" by pushing down on their hindquarters or by simply riding on their backs.
- The sows should be ridden in their own environment, not close to a boar and not when they feed.
- The vulvas are red and swollen. There may also be a slimy, white discharge.
- The sows become restless.
- Fertility reaches a peak about 30 hours after the start of ruttishness.
- The shorter the period between farrow and weaning, the greater the possibility that the sows subsequent periods of heat will be irregular.
- A close watch should be kept on sows for ruttishness. The boar should be brought to the group of sows every morning. Sows that are ruttish will seek out the boar.
- Sows come on heat again four to six days after weaning.
- Sows should be relatively lean before pairing but on a nutritional level where their weight increases. From weaning to first ruttishness, they should eat about 3 kg per day.
- Sows that do not come on heat twice should be removed from the herd.
- Sows should not be serviced for the first time before they have reached a mass of 110 kg and are seven to eight months old. This should be about the third time that the sows come on heat after puberty.
- It is advisable for the sow to be taken to the boar three times at 12-hour intervals. The sow is therefore serviced three times during her period on heat.
- In the case of boars, the first ripe sperm and ejaculation occurs at five to six months of age. Boars should not be used for servicing before they are eight months old.
- The fertility of boars improves up to 12 months of age. Before 12 months, boars should not be used for more than four services per week and a maximum of one per day. One day should be allowed between services.
- Young boars should first service a few young sows before they are used on adult sows, since adult sows could be too aggressive.
- Puberty in boars can be brought on sooner by putting ruttish boars and sows in pens next to one another.
- Adult boars should not service more than one sow per day, with not more than six services per week and with rest periods of one to two days in between.
- Boars should not service more than 15 to 20 sows per season.
- An overworked boars fertility can decrease significantly.
- A boar that is used too little can have a negative influence on subsequent services.
- If a big, heavy boar has to service a young sow, a servicing crate is essential.
- The floor of the servicing part should not be too smooth and the boar should be familiar with the environment.
- Servicing should not take place without supervision. Help should be given if necessary.
- Sows should always be brought to the boars.
- After servicing, sows should be taken back to their own pens to prevent injury by the boars.
TS Brand, B Aucamp, J Botha & A Kruger
ELSENBURG / Research