Breeding Management on Pasture
by Richard Cobb, University of Illinois
In an ideal breeding season, a healthy, a fertile ewe in a weight gaining condition will come into heat and seek out and mate with a healthy, fertile ram of average or above condition score. Two or more of the eggs she ovulates will be fertilized by the sperm of the ram. The fertilized eggs will float in her uterus for up to 30 days and then attach to her uterine wall and develop into twin or triplet lambs which she will give birth to in five months.
Many decisions affecting the success or failure of a breeding season are made before the season begins. Producers should cull from their flock all ewes that have been poor or problem producers in the last year. In small flocks an average culling rate of 10 to 15% is normal. Any purchased ewes or rams should arrive on the farm long enough in advance of the breeding season so that they can be quarantined and evaluated for diseases and then introduced to your program. In addition, ewes need to be fed so that they are in a weight gaining condition at the time rams are introduced to them.
Ewes and rams should be given breeding soundness exams prior to the season. Both sexes should have a breeding season condition score of at least 2.75 to 3.0 with sound teeth, feet and legs.
The udders of the ewes should be evaluated for udder size and lumps. In addition, the teats should be evaluated for size and location. Often records are necessary to determine the history of the udder and teats.
Rams should have two large firm feeling testicles that are swelling and lump free. The Epididymis should also be firm and the size of a walnut. The sheath should not be damaged and the Penis should move freely in the sheath. Finally the Vermiform appendage (worm) should be intact.
Standard breeding practices:
1.Sort ewes on condition score 30 days prior to ram introduction and supplement thin ewes so they are in at least an average condition score at breeding.
2.Worm all ewes 30 days prior to the start of breeding.
3.Flush ewes: Feed ewes so they are gaining weight prior at the start of the breeding season.
4. Vaccinate ewes to prevent abortion due to Vibriosis and Chlamyda.
5.Shear rams at least 30 days prior to breeding.
6.Use teaser rams prior to breeding season to stimulate ewes.
7.Plan breeding seasons. Do not run rams with ewes all year long.
8.Record breeding dates. This is to know when lambing can be born but also to check on the fertility of rams.
9.In the case of a commercial situation; Use three rams rather than two. If two fight to establish dominance, the third can breed the ewes.
The above procedures are necessary prior to a successful breeding season. They give the shepherd an increased chance to produce more healthy lambs.
Management during the breeding season is just as important as procedures before the season to insure a successful season.
We know that up to 30% of the eggs shed at ovulation fail to develop into lambs due to:
1.Eggs failing to be fertilized
2.Fertilized eggs failing to implant
3.Fetuses being reabsorbed.
The main cause of these losses is STRESS. Stress comes in many forms, a few of which are:
All these stresses are important for the entire gestation period, however, they seem to be most important for the first 45 days the ewe is pregnant. Let’s look at these and determine what a producer can do to eliminate or attempt to control.
There is not a great deal we can do about the weather. We know that extended hot days over 90 degree with high humidity can reduce the fertility of breeding rams. It can also increase the stress on the ewes and can contribute to them not conceiving.
Environmental stress is not just hot, humid weather, it is also a sudden storm, high rainfall, prolonged cold, wet or dry spells as well. All of these can cause problems. When these things happen, the shepherd must respond in a positive manner.
To reduce the chance of heat stress producers can:
- expose ewes later in the year (October - December) rather than early (August –September)
- Do not work or do check heats on ewes during the heat of the day but rather in early morning.
- Develop a habit of walking through the ewe flock each day of the year. This is great for observing the ewes, but will condition them to you being present and they will not run away or even move away and possibly develop heat stress.
- Supply adequate shade for all sheep in each pasture.
- Supply clean water in each pasture at all times
- New conceptus is sensitive to heat stress for its first two weeks
- Even after a successful implantation, stress in the early stages of pregnancy can cause the ewe to reabsorb a fetus
To have a truly successful breeding season ewes have to have above average level on nutrition for the duration as well as after the breeding season.
Factors a producer needs to be aware of and control to the best of his/her ability:
- Be aware of the amount of feed available to the ewes at all time. This should be assessed on your daily walk through the ewe flock.
- Move the ewes from one pasture to another according to the amount of feed remaining in the pasture and not just the number of days the flock has been in the pasture.
- Adjust the size of the pasture as needed if using electro netting
- Be ready to supplement ewe flock if available forage is not sufficient
- A sudden change in nutrition can be very stressful
- Do not chase or herd flock to new pasture, rather let ewes walk at their own speed.
- Never handle animals in a rough manner
- Do not force or allow flock to run when being moved
- Teach the ram to come to you for supplemental feeding, halter break for easier handling.
- Teach the ram to come to you for supplemental feeding and to check crayon or marker each day. Be extremely watchful of any rams. NEVER tease or rub the head of any of your rams, as this will be seen by him as a threat. He will retaliate to put you in your place.
- Remove any rams that butt or hit ewes
- Be very careful when using dogs around the flock. A well-trained dog is an asset; a poorly trained dog is a liability
- Sheep spend most of their time either grazing or resting.
- They will graze 8-13 hours a day.
- Grazing is concentrated at dawn and dusk
- Most grazing is during daylight hours lasting 20 to 90 minutes grazing and then 45 to 90 minutes resting or ruminating.
- Rest and rumination is extremely important to the every day mind set of the sheep.
- We work sheep when we feel like it
- It may be best for the animal if we work them while they would be grazing rather than disturbing them while they are resting.
- Loud noises are as disruptive to sheep as electric prods.
- When we move sheep they should be allowed to move at their own speed, rather than be moved at a run or fast walk.
- Slow is Faster
- If you have a sheep with a problem and have to isolate it, put it in a pen with another sheep to keep it company. Sheep are flock animals
- If the weather is cold or if they are grazing poor quality forage, sheep will spend more time grazing.
Shepherds need to put more effort into the breeding season than we typically do. This is the most important season or time of the year. What happens during the breeding season creates the basis of all other season for the flock during the year. To become more knowledgeable about the breeding season:
1.Read as much as you can – Do internet search
2.Talk with other produces about what they do
3.Pay close attention as to what you do each season and if it is successful