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

Goats Are Generally Really Good At Reproduction!

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 percentage

Low death loss.

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.

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.

Reproductive Organs of the Buck

Scrotum Testicles Epididymus Accessory

sex glands Vas

deferens Penis

The Scrotum Two-lobed sac that

encloses the testes. Its main function is in

temperature regulation.

Cremaster muscle raises and lowers testes

Improper scrotal function and poor testicular distention during hot weather may lead to temporary infertility in bucks

Testicles The primary sex organ of a

buck and weigh about 100-150 grams

Suspended in the scrotum outside the body

Two main functions: Produce

Sperm Male hormone testosterone. Failure of one or both testes

to descend into the scrotum is known as cryptorchidism.

Epididymis

Carries 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.

Vas Deferens Primary 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 cells

Prevents the passage of sperm from the epididymis to the urethra.

Penis Main 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 extension

Accessory Sex Glands Includes the ampulla,

seminal vesicles, prostate gland and the bulbo-urethral gland

Function together to secrete fluids that make up seminal fluid.

Sperm cells are suspended and transported within this seminal fluid

Reproduction in the Doe Female serves several functions in

reproduction: 1. Provide ova (eggs) 2. Provide proper environment for fertilization 3. Nurture the embryo/fetus (gestation) 4. Deliver fetus to exterior 5. Feed the young goat (lactation)6. Provide for proper behavior patterns

Attracting male and mating Demonstrating maternal functions

Reproductive Organs of the Doe

Ovaries Oviducts Uterus Cervix Vagina Vulva

Ovaries Have two

principle functions: 1) production of eggs (ova) 2) secretion of female hormones (estrogen and progesterone)

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.

Uterus Small muscular organ

that provides protection and nourishment for the developing embryo.

It consists of a body and two uterine horns

Inner lining of the uterus is made up of many button-like projections known as carunucles

Transfer of nutrients between the doe and the developing embryo takes place via the placenta.

Cervix Muscular 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.

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.

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.

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 15-24 days.

Estrous Cycle

The estrous cycle of a goat can be broken down into four periods: Estrus Metestrus Diestrous Diestrus.

Estrus Estrus 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 25-40 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).

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.

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

Proestrus

Proestrus lasts from 2-4 days. Gradual increase in sexual

behavior and receptivity

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.

Factors Affecting Reproduction

Puberty Seasonality Libido Heredity Age of dam Temperature Nutrition

Puberty The 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.

Seasonality Considered short-day breeders. Normally, September through January is the

season of peak breeding activity In 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).

Libido Buck 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).

Heredity As 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.

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.

Temperature

In 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.

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.

Nutrition Reproduction of the doe can be enhanced by a

well-managed feeding program. Doe size is determined by nutrition and

genetics Larger does in a herd are more likely to

produce multiple births than smaller, under-nourished does

Proper plane of nutrition important throughout gestation to help build body condition reserves; maintain pregnancy; and ensure healthy, vigorous kids at birth

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 estrus

Shown increases in litter sizes

Gestation

In goats the gestation length ranges from 146-155 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.

The Normal Reproductive Characteristics Does

TRAIT AVERAGE RANGEAge at Puberty (mos) 5-7 5-20Estrous Cycle Length (d) 21 15-24Duration of Estrus (hrs) 30 24-48Ovulation After Estrus Beginning (hrs) 33 30-40Gestation Length (d) 149 144-155Litter Size 1.5 1-

4Breeding Weight -- 60-75% of Adult Wt

The Normal Reproductive Characteristics Bucks

TRAIT AVERAGE RANGEAge at Puberty (mos) 4-6 5-20Breeding Age (mos) 8-10 6-12Breeding Ratio (Mature Buck) 1:40 1:35-60 Breeding Ratio (Young Buck < 1yr. Old) 1:20 1:10-25Daily Sperm Prod. (billion) 6.0 4.8-7.2Ejaculate Volume (ml) 1.0 0 .5-1.5Ejaculate Conc. (billion/ml) 3.0 1 .5-

6.0

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%

Selecting a Breeding Buck Pedigree Growth traits Multiple births Conformation Avoid inbreeding, thin or fat bucks Avoid bucks with birth defects Scrotal circumference is the most

important reproductive trait for selection

Breeding Soundness Evaluations in Bucks

Done with newer purchased bucks or herd breeding problems

Physical Examination Exam of the reproductive tract Scrotal Circumference Semen analysis

Volume=0.5cc Concentration =200

million per ml Motility=70% Normal morphology=80%

Selecting Does for Reproduction

Polled Body condition Conformation Attachment of mammary gland Normal vulva Multiple births, growth Avoid birth defects

Sexual Behavior in Goats

Is both instinctive and learned Sexual behavior begins before

sexual maturity (3 months of age) Sex drive is heritable and varies in

the goat population

Signs of Heat in the Doe

Seen best in sight and sound contact of a buck

Standing to be mated! Seeking out the buck Vocalization Swollen vulva with mucous discharge Flagging and increased urination

Breeding Systems for Does

Most are pasture bred The stocking rate varies but one

buck per 20 to 100 does is most often recommended

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 used Works best if does are all cycling well 2 injections of prostaglandins given 10 days

apart Progesterone as an implant or vaginal implant No product is cleared by the FDA for goats

Artificial Insemination Uses frozen semen Broader use of better or distant

bucks Requires time, training, equipment

and management Conception rates of

50 to 75% have been reported with skilled inseminators

Embryo Transfer

Increases the reproductive rate for does but at a cost

3 pregnancies per procedure

Steps in Embryo Transfer Donor selection Recipient selection Estrous synchronization of

donor and recipients Superovulation of donor Breeding donor Embryo recovery Putting embryoes in recipients

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%+)

Pregnancy Facts Average length is 150 days Restlessness for 12 hours Labor for 2 hours or less Afterbirth falls away at an average of 6

hours 95% of kiddings do not require help Examine does after 1 hour of labor

Caring for newborn kids

Let the does do it if she will! Dry kids off Rub the chest to stimulate

breathing Dip the navel with iodine Give colostrum if in doubt

Pseudopregnancy in Does The doe acts and looks pregnant but is

not 3-5% of dairy does on some farms More likely with late fall pregnancies They “deliver” a large amount

of clear fluid and may repeat in later years.

Consider culling

Cystic Ovarian Disease

2% of does affected Affected does show heat every few

days but do not become pregnant Does may be treated but culling is

a good idea

Abortion in Does Expelling a fetus before it can live Up to 5% of healthy does may abort Diagnosis requires a diagnostic lab Toxoplasma, Chlamydia and other

causes have been diagnosed

Intersex Condition in Goats

Associated with being polled and dairy breeds

Animals are genetic females but have a mixture of reproductive organs

They are sterile and should be culled

THE END

Questions?