Presentation on theme: "Reproductive Management of Meat Goat Operations"— Presentation transcript:
1 Reproductive Management of Meat Goat Operations Fred Hopkins-Dept of Large Clinical Sciences and Animal Science-UTKKyle Rozeboom- Dept of Agriculture and Natural Resources-UTM
2 Goats Are Generally Really Good At Reproduction!
3 Reproduction is the most important factor that determines the profitability of a meat goat operation.Main goal for meat goat production:Optimum litter size (2-3 kids) with a high weaning percentageLow death loss.
4 The purpose of the reproductive management section is to provide information that will help improve the reproductive performance and consequently, the profitability of meat-goat operations.
5 The Structure and Function of the Reproductive System of the Buck and Doe A thorough understanding of the male and female reproductive tract is important for any producer as they try to improve the reproductive rate of their herd.
6 Reproductive Organs of the Buck ScrotumTesticlesEpididymusAccessory sex glandsVas deferensPenis
7 The Scrotum Two-lobed sac that encloses the testes. Its main function is in temperature regulation.Cremaster muscle raises and lowers testesImproper scrotal function and poor testicular distention during hot weather may lead to temporary infertility in bucksDuring periods of cold weather, the smooth muscle that lines the scrotum, in conjunction with the cremaster muscle that surrounds the spermatic cord, contracts and causes the scrotum to draw the testicles closer to the body.During periods of hot weather, these muscles relax allowing the testicles to distend down away from the body.The surface of the scrotum stretches, allowing a greater surface area.The surface contains both sweat and sebaceous glands (oil producing gland of the skin). Evaporation of the excretions of the glands cools the surface of the scrotal tissue and the testicles.
8 TesticlesThe primary sex organ of a buck and weigh about gramsSuspended in the scrotum outside the bodyTwo main functions: ProduceSpermMale hormone testosterone.Failure of one or both testes to descend into the scrotum is known as cryptorchidism.In mature bucks, they may change in size during the breeding season.
9 EpididymisCarries the sperm from the testicle to the vas deferens then to the penis.Sperm continue to develop (mature) in the epididymis and are stored there.
10 Vas DeferensPrimary function is to move sperm into the urethra at the time of ejaculation.Removing or closing off a section of the vas deferens is known as a vasectomy.In vasectomized animals (teaser bucks) the animal still produces testosterone and sperm cellsPrevents the passage of sperm from the epididymis to the urethra.It is a slender, muscular tube that runs from the tail of the epididymis to the neck of the bladder, where it joins the ampulla and accessory sex glands.
11 PenisMain function is to deposit semen in the female reproductive tract.It also serves as the passage for urine to the exterior.Sigmoid flexure (S-shaped portion) straightens upon erection; allows for extensionIn the non-erect state, the glans of the penis is contained in the sheathMating time is very short in bucks. Intromission usually lasts less than 5 seconds. Bucks will generally throw their head back at ejaculation.
12 Accessory Sex GlandsIncludes the ampulla, seminal vesicles, prostate gland and the bulbo-urethral glandFunction together to secrete fluids that make up seminal fluid.Sperm cells are suspended and transported within this seminal fluidNormal seminal volume during ejaculation for a buck is ml, with a concentration of billion sperm cells/ml.Seminal fluid provides a medium for sperm transport, as well as providing energy substrates, buffers and nutrients needed to assure sperm cell motility and survival within the vagina and female reproductive tract
13 Reproduction in the Doe Female serves several functions in reproduction:1. Provide ova (eggs)2. Provide proper environment for fertilization3. Nurture the embryo/fetus (gestation)4. Deliver fetus to exterior5. Feed the young goat (lactation)6. Provide for proper behavior patternsAttracting male and matingDemonstrating maternal functions
14 Reproductive Organs of the Doe OvariesOviductsUterusCervixVaginaVulva
15 Ovaries Have two principle functions: 1) production of eggs (ova) 2) secretion of female hormones (estrogen and progesterone)The ovary differs from the testicles in that they only produce 1-3 eggs per cycle near the end of the heat period.
16 Oviducts (fallopian tubes) Provide the site of fertilization and early embryo development before the embryo passes to the uterus.Transport the ova from the ovary to the site of fertilization which occurs midway down the oviduct.At the same time, moves the sperm cells in the other direction towards the ova from the uterus.
17 UterusSmall muscular organ that provides protection and nourishment for the developing embryo.It consists of a body and two uterine hornsInner lining of the uterus is made up of many button-like projections known as carunuclesTransfer of nutrients between the doe and the developing embryo takes place via the placenta.caruncles (attachment sites for the placenta)
18 CervixMuscular canal-like structure that provides closure to the uterus of a doe.Protects the uterus during pregnancy.During breeding, the cervix also assists the movement of sperm from the vagina to the uterus.The cervix is tightly closed and sealed during pregnancy.Cervix also acts as a sperm reservoir and prevents the transport of damaged or dead sperm cells to the uterus
19 Vagina The site of semen deposition by the buck during natural mating. Once deposited, sperm cells are transported into the cervix and seminal fluid is either absorbed by the vagina or expelled.
20 Vulva The external opening of the female reproductive tract. It serves as the entrance for the penis during breeding and is the end of the birth canal during parturition.It is the opening for both the urinary and genital tracts.
21 Estrous Cycle Goats are classified as seasonally polyestrous. This means that does have multiple estrous cycles only during certain periods of the year.This period normally occurs during the fall in goats.Normally 21 days in length and can range from days.
22 Estrous CycleThe estrous cycle of a goat can be broken down into four periods:EstrusMetestrusDiestrousDiestrus.
23 EstrusEstrus is the period of sexual receptivity where the doe will stand (standing heat) to be mated by the buck.Lasts around 30 hours in a doe but can range from hours.Rapid tail wagging, mounting and bleating in does are all secondary signs of estrus in does.Ovulation of 1-4 ova usually occurs at the end of estrus or few hours after estrus ends (metestrus).During estrus the female is under the control of estrogen and will display female mating behavior.
24 Metestrus Metestrus begins at the finish of estrus. It will normally last for 3-5 days.This is the period where the beginning formation of the corpus luteum (C.L.) takes place.Ovulation can occur during this phase in does.The C.L. is responsible for the secretion of the hormone progesterone.Progesterone is considered the hormone of pregnancy and is responsible for maintaining a pregnancy in does that have conceived.
25 Diestrus Diestrus lasts between 10-14 days and follows metestrus. During this period the C.L. is fully functional and the secretion of progesterone is at its greatest point
26 Proestrus Proestrus lasts from 2-4 days. Gradual increase in sexual behavior and receptivityBy day 17 the endometrial lining of the uterus can recognize that no embryo is present. This causes a release of prostaglandin, which lyses(removes) the C.L. The C.L regresses, removing the doe’s source of progesterone. The doe now comes under the control of estrogen, which is being released by the ovary. Rapid follicular growth occurs and the doe begins to exhibit behavioral symptoms of the approaching estrus.
27 Factors Affecting Reproduction Many factors affect reproductive efficiency in the goat. Fertility and prolificacy of the male and the female is determined by many genetic and environmental conditions.
28 Factors Affecting Reproduction PubertySeasonalityLibidoHeredityAge of damTemperatureNutrition
29 PubertyThe age at which an animal is capable of releasing gametes (spermatozoa and ova) and copulating.Can occur from 4-20 months of age.Influenced by factors such as breed, size, crossbreeding, inbreeding, health, nutrition and season of birth.Most doelings reach puberty by the time they reach 2/3 of their expected mature body weight and are bred in their second year of life.Bucks normally reach puberty at 4-6 months of age and doelings at 5-7 months of age.Larger breeds tend to be slower to reach sexual maturity than to smaller breeds.Within a breed, those goats that grow faster tend to reach puberty more quickly than slower-growing contemporaries.
30 Seasonality Considered short-day breeders. Normally, September through January is the season of peak breeding activityIn seasonal breeders, both males and females are affected by photoperiod (the duration of an organism's daily exposure to light) with each showing the greatest fertility during the fall breeding season (short daylight length).This means they are in anestrus (an interval of sexual inactivity)during the spring and summer, and only cycle and breed during the fall when the days are getting shorter.Breeding season begins when the ratio of daylight to darkness begins to decrease and usually ends when the ratio of daylight to darkness is nearly equal.During the spring and summer, bucks will often experience a reduction in sperm production, and a higher incidence of abnormal sperm cells. In some cases, bucks will become sexually inactive during the spring and summer.
31 LibidoBuck activity and fertility play a major role in the reproductive rate of a doe.A strong libido is necessary for a buck to breed a high number of does during the breeding season.Factors such as body condition, genetics, environmental temperatures, and disease and parasites affect libido.It is important to maintain an acceptable buck-to-doe ratio (1:50 or less is recommended for mature buck).There also appears to be an advantage to running bucks in groups versus alone.Exceeding this ratio may lead to a buck experiencing sexual exhaustion, leading to decreased libido and increased health and physical problems.Body condition is also closely related to libido, as bucks that are obese, thin or undernourished have decreased libido.
32 HeredityAs in other species, some breeds and genetic lines of goats produce more multiple births than do others.Nubian goats, for example, are well known for prolificacy and commonly give birth to triplets.Also, within a herd selection of replacements based on the dam’s ability to produce twins can increase the overall prolificacy of a goat herd.It has been shown that bucks from more prolific breeds appear to be more fertile than those from less prolific breeds.
33 Age of dam Age affects the reproduction rate of does. A doe increases in fertility and prolificacy as she approaches middle age (5-7 years).Middle-aged does produce a higher number of twins than do 2-year old does.It is recommended retaining these does in your flock as long as they remain functional and sound in their structure and mammary system.
34 TemperatureIn the doe, temperatures above 90 degrees F for an extended period of time can decrease embryo survival and retard fetal development.High temperatures in latter gestation may cause smaller, weaker kids to be born.Lower sperm concentration, decreased sperm motility and a higher number of dead and abnormal sperm are all related to heat stress in bucks.Extended periods of exposure to temperature above 100 degrees have been shown to cause bucks to become less fertile.The mortality rate of embryos is especially high if does are subjected to these high temperatures from breeding to 8-10 days post breeding.Fat does or those on excessive feed consumption are generally more affected by heat stressHeat Stress Damage to the buck is not usually permanent and the bucks are usually fertile after 4-6 weeks of cooler temperatures.
35 Temperature To counteract heat stress Provide good shade and proper air circulation to keep bucks and does comfortable.Minimize activity by not working goats during periods of excessive heat.During breeding season it may also be necessary to keep bucks penned up in the shade in a cool place up during the daytime when the temperature is at its greatest, and only allow the bucks to breed at night. This will minimize activity and lower the affects of heat stress on the buck.
36 NutritionReproduction of the doe can be enhanced by a well-managed feeding program.Doe size is determined by nutrition and geneticsLarger does in a herd are more likely to produce multiple births than smaller, under-nourished doesProper plane of nutrition important throughout gestation to help build body condition reserves; maintain pregnancy; and ensure healthy, vigorous kids at birthDoes that are thin, have a mineral imbalance or in a negative plane of nutrition (losing weight) will be more likely to have lower pregnancy rates, fewer numbers of multiple births and weaker kids than those with a stable or increasing plan of nutrition.Bucklings on a high level of nutrition will reach puberty earlier than those on an inadequate diet. Testicular size is also related to body growth and development.Research has shown that the testicular size of buck kids is positively correlated to the ovulation rate of their doe siblings.
37 Flushing Has shown to increase prolificacy in thin does Flushing is an increase in the doe’s plane of nutrition 2-8 weeks prior to breeding season so that the doe is in a gaining state before and during estrusShown increases in litter sizesFlush doe by turning out on a high-quality, pasture or feeding lbs of grain per head per dayFlushing will improve ovulation rate, which can result in a percent increase in the number of kids produced in a herdResponses to flushing are greater in does that are thin to moderate in body condition, no response in fat ewes.
38 GestationIn goats the gestation length ranges from days, with 149 as standard.Influenced by genetics, maternal and fetal factors.During gestation, many changes must take place for the doe to prepare herself and the offspring for parturition.Inadequate nutrition of the doe, especially in late gestation, can result in weak kids and a higher death loss.It has generally been observed that younger does will have shorter gestation terms than older does.It has been shown that singles tend to be carried longer than multiple births and males longer than femalesA doe must be provided the proper nutrition and health management
39 The Normal Reproductive Characteristics Does TRAIT AVERAGE RANGEAge at Puberty (mos)Estrous Cycle Length (d)Duration of Estrus (hrs)Ovulation AfterEstrus Beginning (hrs)Gestation Length (d)Litter SizeBreeding Weight % of Adult Wt
40 The Normal Reproductive Characteristics Bucks TRAIT AVERAGE RANGEAge at Puberty (mos)Breeding Age (mos)Breeding Ratio(Mature Buck) : :35-60(Young Buck < 1yr. Old) 1: :10-25Daily Sperm Prod. (billion)Ejaculate Volume (ml)Ejaculate Conc. (billion/ml)
41 Heritability of Important Goat Traits *Age at 1st kidding=50%*Multiple births=15%Weaning weight=45%Weight at 7 mo.=60%Mature body weight=50%*Milk yield=50%Stature=50%Carcass weight=45-50%Quality grade=40%Ribeye area=40 to 45%Cutability=25 to 30%Muscling=40 to 45%Notice that a couple of these traits(*) are related to reproduction, though most are not.Improvement in reproductive performance is usually best accomplished by improved management.
42 Selecting a Breeding Buck PedigreeGrowth traitsMultiple birthsConformationAvoid inbreeding, thin or fat bucksAvoid bucks with birth defectsScrotal circumference is the most important reproductive trait for selectionReproductive traits are not usually a part of selection of breeding animals.
43 Breeding Soundness Evaluations in Bucks Done with newer purchased bucks or herd breeding problemsPhysical ExaminationExam of the reproductive tractScrotal CircumferenceSemen analysisVolume=0.5ccConcentration = million per mlMotility=70%Normal morphology=80%This is not often done on bucks except when a problem with pregancy rate is encountered.Scrotal circumference relates well to daily sperm outputMotility is % movingMorphology is % shaped and formed normally
44 Selecting Does for Reproduction PolledBody conditionConformationAttachment of mammary glandNormal vulvaMultiple births, growthAvoid birth defects
45 Sexual Behavior in Goats Is both instinctive and learnedSexual behavior begins before sexual maturity (3 months of age)Sex drive is heritable and varies in the goat populationThese goats are young, penned and excited. They are practicing!
46 Signs of Heat in the DoeSeen best in sight and sound contact of a buckStanding to be mated!Seeking out the buckVocalizationSwollen vulva with mucous dischargeFlagging and increased urinationStanding to be mated is by far the best sign of heat
47 Breeding Systems for Does Most are pasture bredThe stocking rate varies but one buck per 20 to 100 does is most often recommended
48 Estrous Synchronization Hormones can be used to have does come in heat at about the same time.Is used to shorten the kidding season, or when AI is usedWorks best if does are all cycling well2 injections of prostaglandins given 10 days apartProgesterone as an implant or vaginal implantNo product is cleared by the FDA for goatsDetails of programs vary and goats respond variably according to breed and other factors.
49 Artificial Insemination Uses frozen semenBroader use of better or distant bucksRequires time, training, equipment and managementConception rates of to 75% have been reported with skilled inseminatorsDoes are fairly easy to inseminate, but catching them in heat may be a problemMost does are bred in milking stands rather than flipped over like this one.
50 Embryo Transfer Increases the reproductive rate for does but at a cost 3 pregnancies per procedureSuccessful embryo transfer requires specialized training and lots of experience
51 Steps in Embryo Transfer Donor selectionRecipient selectionEstrous synchronization of donor and recipientsSuperovulation of donorBreeding donorEmbryo recoveryPutting embryoes in recipientsObjective measures of what make a superior female are hard to come by in the goat worldRecipients should be healthy, fertile females rather than cullsRecipients must be in heat at about the same time as donors for pregnancy to occurCollecting several embryoes per procedure brings down the cost per pregnancy
52 Pregnancy Diagnosis in Does Wait for kidding (150 days-100%)Blood or milk progesterone (19 to 24 days-90%)Blood or urine estrone sulfate (50 to 60 days-near 100%)Radiography (after 70 days-near 100%)Ultrasound (after 35 days-90%+)The range or earliest date the technique is useful and its estimated accuracy is listed in parentheses.
53 Pregnancy Facts Average length is 150 days Restlessness for 12 hours Labor for 2 hours or lessAfterbirth falls away at an average of 6 hours95% of kiddings do not require helpExamine does after 1 hour of labor
54 Caring for newborn kids Let the does do it if she will!Dry kids offRub the chest to stimulate breathingDip the navel with iodineGive colostrum if in doubtLet the doe do her job and bond with the kid if at all possible.
55 Pseudopregnancy in Does The doe acts and looks pregnant but is not3-5% of dairy does on some farmsMore likely with late fall pregnanciesThey “deliver” a large amount of clear fluid and may repeat in later years.Consider cullingThe animals health is not affected.Some hormone measurements will inaccurately call affected animals pregnant.
56 Cystic Ovarian Disease 2% of does affectedAffected does show heat every few days but do not become pregnantDoes may be treated but culling is a good ideaTreatment with hormones may help but affected does tend to have the problem again.Female offpring of affected does are thought to be more likely to have this problem.
57 Abortion in Does Expelling a fetus before it can live Up to 5% of healthy does may abortDiagnosis requires a diagnostic labToxoplasma, Chlamydia and other causes have been diagnosedThe cause of abortion can not be determined by just looking at aborted goat fetuses or aborting does.
58 Intersex Condition in Goats Associated with being polled and dairy breedsAnimals are genetic females but have a mixture of reproductive organsThey are sterile and should be culledThis is what appears to be testicles on either side of a small, malformed vulva