Basic Reproductive Management

Reproduction should be a vital component of the overall herd management scheme and closely integrated with nutritional and health management. The incidence of reproductive diseases affecting goats in the U.S. is low, but goats need to be maintained in good health (dewormed and vaccinated) to ensure proper reproductive function. Meat-type does should be capable of giving birth and raising their offspring unassisted, but occasional help may have to be provided with complications during parturition and the acceptance of the newborn. Records should be collected on kidding and weaning performance (litter size and weight) to be used for selection of breeding stock.

Mating schedule/system

The traditional mating system for goats is once-a-year, annual mating, with does bred in fall during the natural breeding season for spring kidding. This approach ensures the greatest likelihood to establish pregnancy, and optimal ovulation rates. There is some flexibility as to breeding dates, as the breeding season will usually extend from August to January for most breeds. This range allows breeding to be adjusted for favorable climatic conditions during kidding and optimal forage quality for lactating does. Scheduling a breeding season should also take marketing opportunities for kids into account. Duration of mating will impact the length of the kidding season, and associated labor requirements. A 40-45 days breeding season will afford each doe at least two opportunities to breed.

A gestation length of 150 days presents goats the opportunity to kid twice per year or three times in two years. A decreased kidding interval ('accelerated mating') utilize facilities and labor more effectively, while increasing the annual kid crop and providing for more continuous production of kids. However, this theoretical potential is restricted by seasonal, postpartum and lactational anestrous, and the need for uterine involution, while requiring significant additional inputs in management and feed. These additional inputs often make these systems not suitable for extensive meat goat production.

Under extensive conditions, continuous mating is sometimes practiced, and bucks are maintained with the doe herd throughout the year. In such a system only limited supervision can be provided during kidding, but care is required to routinely remove offspring from the herd to avoid dam x son and sire x daughter matings. Although buck exposure is continuous, kidding under continuous mating will eventually follow seasonal breeding patterns.

Nutritional considerations

Diets and feed supplies have to be adjusted to account for the physiological stage of production of the goat, particularly in the female (lactation, gestation). Prior to breeding (2-3 weeks) does in poor condition should be placed on a gaining plane of nutrition to stimulate higher ovulation rates ('flushing'). The mechanism accounting for this improvement in ovulation rate is not fully understood, nor have results been consistent. It is also not clear if improvements are linked more directly to changes in energy or protein intake, but changes are more pronounced in does where the improved diet results in changes in body condition.

During the early stages of gestation the nutritional demands of does are moderate and only in later stages of pregnancy, at the time of increased fetal growth, the plane of nutrition should be increased. Inadequate nutrition during late gestation can result in abortion, and stillborn and weak kids, and may limit availability of colostrum for the newborn kid. Low nutrition may also affect the acceptance and bonding of the mother. Late pregnant does should have access to high quality roughage, and moderate levels of concentrate feed, as both undernourished or overly fat does are prone to pregnancy toxemia (ketosis) during the late stages of gestation. Does nursing their kids are nutritionally challenged and may require supplemental feed if pastured to ensure adequate milk supply for multiple litters.

Breeding season management

Bucks, because of their size, odor and sometimes temperament, often require special management considerations and experience in handling. Pens and working facilities need to be strong to hold bucks when not used for breeding. Bucks used for breeding should have characteristics that will advance the production potential of the herd and should be able to mate successfully to transmit these characteristics.

As indicated earlier, spermatogenesis is susceptible to outside influences such as elevated temperature, season of year and nutrition, and breeding males need to be evaluated for reproductive soundness 3-4 weeks prior to mating season. Part of such a 'breeding soundness examination' is an evaluation of the overall condition of the buck and includes his health history, physical soundness, particularly of feet and legs, and examination (palpation and visual inspection) of the external genitalia (scrotum and scrotal content, sheath and penis) for signs of infections and other abnormalities. There are currently no age and breed standards for testis size (scrotal circumference) in meat-type breeds, but the testis should be of adequate size (20-25 cm scrotal circumference) and tone (firm).

In case the assistance of a veterinarian or trained personnel is available the breeding soundness examination should also involve the collection and evaluation of an ejaculate. The ejaculate is scored for the percentage of motile, normal and live sperm. If does in estrus are available, bucks should be placed with these does to evaluate libido and mating behavior. Bucks deficient in any part of the examination should be considered questionable, and retested after several weeks. A second failed test would indicate reproductive deficiencies and such a buck should not be used for mating.

The number of does a buck can breed will depend on a variety of factors, including age of the buck, terrain and pre-breeding management (i.e. synchronization of estrus). A mature buck under pasture conditions should be able to breed 30 to 50 does. For yearling bucks this ratio is markedly lower, and dependent on the physical development of the buck. The number of bucks is of less importance if multiple sires are used with a single group of does, but problems with fighting, establishment of dominance, and the ability to establish parentage may occur. A buck may breed only 5-15 does if does are estrus synchronized (hormone treatments that causes all does to be in estrus at the same time) to ensure adequate fertility. An alternative approach to breeding synchronized does is the use of 'hand-mating' where access to the doe is restricted to one or two controlled matings 12 hours apart.

A useful management tool for breeding is the use of a marking harness. A marking harness is a device which holds a marking crayon on the buck's chest which colors the back of a doe when she is mounted. Although most harnesses available on the market are designed for rams (male sheep), adjustments can be made for their successful use with larger bucks. Harness marks will provide an instant confirmation of the breeding activity of a buck, establish mating dates (and subsequently projected kidding dates). The color of crayon should be changed after 15-20 days of breeding to identify does that are rebred, as indicated by marking with the new color. A large number of rebred does would suggest that a buck has fertility problems and should be replaced. In multiple sire mating groups alternative color crayons will provide an indication of mating activity of individual bucks.

Gestation and parturition

Embryonic losses early in pregnancy are usually much higher than fetal losses at later stages of gestation, and can be as high a 20-30%, due to the complexity of events associated with fertilization and implantation. Embryo mortality is also influenced by extrinsic factors such doe age, and environmental and nutritional stress. Abortions during the early stages of gestation can usually not be readily differentiated from failure to conceive. During these early stages of pregnancy the embryo is sensitive to a variety of drugs and mineral deficiencies.

In goats, in contrast to sheep, the placenta does not provide sufficient progesterone, and is dependent on secretions from an active corpus luteum to support pregnancy. Hence spontaneous (non-infectious) abortions resulting from luteal insufficiency are more common in goats. Undernutrition, vitamin and mineral deficiencies, toxic plants, and certain drugs (i.e levamisole) can contribute to non-infectious abortions. Multiple late abortions ('abortion storm') usually suggest an infectious cause for the abortion, of which chlamydiosis and toxoplasmosis are the most common source. To properly diagnose the cause of an infectious abortion, the fetus, portions of the placenta and a blood sample from the doe should be collected for testing.

Parturition can be divided into three stages. During the first stage, the uterine content is pushed toward the cervix, causing it to dilate in a process that may last up to 12 hours. In the second stage contractions increase and the kid(s) move in the birth canal and are expelled in process that may take up to two hours. In the third stage the placenta is expelled and uterine involution commences. Parturition can be induced in goats through the use of prostaglandin which regresses the corpus luteum and removes the primary source of progesterone. Does treated with prostaglandin will usually deliver their kids between 30 to 35 hours after injection, and no further ill effects such as retained placenta and reduced subsequent fertility are generally observed.

Kidding generally should not require human assistance. However, assistance may be needed when a fetus is not presented properly for delivery, or the cervix is not sufficiently dilated to accommodate a large kid (dystochia). Intervention should be considered once the second stage of labor exceeds two hours. In case of failure of the cervix to dilate properly (ringwomb), cautious manual stretching can be applied. Continued failure to dilate may require veterinary assistance and a Cesarian section to deliver the kids. The normal presentation of kids for delivery is with the head positioned between the front legs. Presentation of the hind legs first may also allow the kids to be born without further assistance. However, abnormal presentations such as the head and leg(s) facing back, and multiple kids entangled during birth, will require manual repositioning of the kids by experienced personnel. Once a kid is positioned correctly assistance may be provided by pulling the legs.

Membranes covering the kids will usually rupture during birth and are removed through cleaning by the doe. If membranes cover mouth and nose, and are not attended to by the doe, they need to be removed manually and breathing should be stimulated and the kid(s) dried off. Newborn kids should be nursing within a couple hours of birth to ensure that proper amounts of colostrums are consumed. The udder of the doe should be checked to ensure that milk is present and can be expressed. The navel of the new born kid should be dipped in iodine. In general, handling of new-born kids and does should be limited to allow the proper bond between dam and off-spring to form.

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