The joining of ewes and rams at breeding time seems like a relatively simple task, but there are a lot of important steps that need to be taken several weeks before breeding that can affect both the quality and quantity of next year’s lamb crop. Breeding ewes that are in poor condition can result in fewer eggs fertilized, embryonic abortion, poor fetal development and weak newborns. Rams that are in poor condition may have difficulty servicing ewes resulting in open ewes or a long lambing season. Preparations initiated 4-6 weeks before introducing rams can maximize success during breeding and lead to a healthier, more prosperous lamb crop next year.
Body Condition: Assess the body condition of your ewes and rams at least four weeks before breeding. Ideally, ewes should have a BCS of 3-3.5, while rams should have a slightly higher BCS (3.5-4) since they’ll burn a lot of calories during breeding. Ewes that are healthy and in good condition have higher ovulation and embryonic survival rates, and fetal development is enhanced throughout pregnancy. Underconditioned rams and ewes with a BCS of 2.5 or lower should receive supplemental nutrition several weeks prior to breeding. This is especially important when forage has been negatively impacted by prolonged heat or drought. On the other hand, avoid overfeeding rams prior to breeding. Fat rams tire easily and may lack the stamina needed to service ewes, and excess weight puts unnecessary stress on the ram’s feet and legs. Overweight ewes may have more difficulty conceiving, and excess weight also makes them more susceptible to ketosis, prolapse and dystocia at lambing.
Health Assessment: Prior to breeding, reassess the ewe’s udder for lumps, misshapen teats or evidence of a prior infection that may not have been noticed after weaning. Rams and ewes should appear healthy with no signs of respiratory infection, limping or parasitism. Cull any ewe with evidence of infectious or chronic illness. Breeding unhealthy ewes increases the risk of abortion, pregnancy related illnesses and may result in dead or weak lambs at birth. FAMACHA score ewes and rams prior to breeding to determine if animals require deworming. Anemia caused by parasitism can cause rams to be too listless and sluggish to breed. Ewes need enough healthy red blood cells to sustain a pregnancy. Trim the hooves of rams and ewes before breeding. Rams put a lot of weight and stress on their rear legs and feet when mounting ewes. A lame ram cannot service ewes effectively. Overgrown hooves can cause mobility problems in ewes during late pregnancy which could affect their ability to graze, putting them at higher risk for pregnancy toxemia and other nutrition related problems.
Pairing/contemporary groups: If using more than one ram, plan your breeding groups carefully. The best way to evaluate a ram’s level of performance is by comparing the performance of his offspring for specific traits of interest (i.e.. growth, parasite resistance) with the offspring of other rams under the same management. Sometimes these differences in the offspring can be significant. To make accurate comparisons, each ram should be bred to a similar group of ewes that are representative of your ewe flock. Divvy up the ewes for each ram so that each breeding group has a similar number of high-quality and low-quality ewes, mature ewes and ewe lambs, and enough ewes per ram to accurately compare offspring. NSIP flocks have the added advantage of “Sheep Tools” to help you select pairings based on EBV strengths and weaknesses and to determine inbreeding coefficients for each pairing.
Environment: High temperatures can significantly reduce ram fertility resulting in reduced pregnancy rates and lambing percentages. Heat stress can reduce a ram’s sperm count for up to 60 days. It is important that rams have a complete breeding soundness exam prior to breeding, especially if they’ve been exposed to extreme or prolonged heat in the weeks leading up to breeding. Heat stress can also affect ewe fertility and embryo survival, especially in the first weeks of pregnancy. When breeding in late summer or early fall, it is important that sheep have access to a cool, shady area to reduce the risk of heat stress.
Breeding Soundness Exams (BSE): Ideally, rams should have a breeding soundness examination (BSE) by a veterinarian to determine semen quantity and quality and to identify any scrotal defects that could affect breeding capability. If a veterinary BSE is not possible, it is advisable to use a different ram as a clean-up in the last two weeks of breeding in case the original ram’s fertility was compromised. Ideally, a clean-up ram is one that is known to be fertile (previously used or tested) so that he can effectively cover any ewe left open after the first 35 days of breeding.
Flushing: Flushing is the practice of increasing a ewe’s plane of nutrition from two weeks prior to breeding through 30 days after joining. Flushing increases ovulation rates and embryonic survival. Flushing can be as simple as moving ewes to a lush pasture or by supplementing them with grain or high-quality hay. Underconditioned ewes respond more favorably to flushing compared to over-conditioned ewes or ewe lambs.
Teasing: Using a vasectomized ram or teaser ram can stimulate ewes to begin cycling (usually within 3-5 days) in preparation for breeding. The first ovulation (or silent cycle) often results in the release of a single egg. Replace the teaser ram with the breeding ram after the first silent cycle is complete, usually within 10-14 days. Using a teaser ram can increase ovulation rates leading to more twin births and a shorter lambing window. If you do not have a teaser ram, fence line contact with breeding rams for at least a week before joining will have a similar effect. However, the fence needs to be strong and a group of excited rams may start fighting as ewes begin to cycle. The use of a teaser ram is less effective if ewes have been kept in close proximity to rams prior to breeding.
Harness/raddle paint: The use of a breeding harness or raddle paint has several advantages. When a ewe gets marked it tells the producer that a ewe is in heat and approximately when she is likely to lamb. If a ewe is remarked, it tells the producer that there could be a problem with the ewe’s or ram’s fertility, more often the latter. It is not unusual for eager rams with high libido to mark ewes that are not in heat on the first day or two after joining, so watch for remarking 14-17 days later. The color of the marker or raddle paint should be changed after the first 17 days so that any ewe that is remarked is easily noted. If several ewes in a breeding group have been remarked, the ram should be replaced. If a clean-up ram is used, a third (darker) color should be used on his marking harness. It is not uncommon for a harness to loosen during breeding and therefore may require frequent adjustments. Raddle paint can be messy and laborious requiring frequent reapplications.
Breeding ewe lambs: Ewe lambs can be bred if they have reached 70% of their mature weight; in Katahdins around 90-100 lbs. Early maturing ewe lambs that breed at 7-9 months of age are likely to be more prolific over their lifetime. If ewe lambs are not bred until 18 months or older, be careful not to overfeed them. Excess fat can deposit in the udder resulting in reduced milk production in the future.
Remember, the preparations you make weeks before breeding can have profound affects at lambing time.
By: EAPK Communications Committee
