1 Unit B Understanding Animal Body Systems Lesson 7 Understanding Animal Reproduction

11

Unit BUnit BUnderstanding Animal Body Understanding Animal Body

SystemsSystems

Lesson 7Lesson 7

Understanding Animal ReproductionUnderstanding Animal Reproduction

22

TermsTerms AnestrusAnestrus Artificial Artificial

inseminationinsemination CastrationCastration CervixCervix CopulationCopulation DiestrusDiestrus EggEgg EjaculationEjaculation Estrous cycleEstrous cycle

EstrusEstrus FertilizationFertilization GestationGestation HeatHeat InseminationInsemination LactationLactation MetestrusMetestrus Natural inseminationNatural insemination NeuteringNeutering

33

TermsTerms

OvaryOvary OviductOviduct ParturitionParturition PenisPenis ProestrusProestrus Prostate glandProstate gland PubertyPuberty

44

Why is reproduction important? Why is reproduction important? ReproductionReproduction is the process by is the process by

which animals produce offspring.which animals produce offspring.

Offspring are the same species and Offspring are the same species and have traits of their parents.have traits of their parents.

Parents are selected and mated to Parents are selected and mated to achieve certain goals with offspring. achieve certain goals with offspring.

55

Goals of ReproductionGoals of Reproduction Examples of goals include to Examples of goals include to

produce offspring with high milk produce offspring with high milk productivity or meaty carcasses.productivity or meaty carcasses.

Reproduction results in new Reproduction results in new animals that are raised for the animals that are raised for the products they produce.products they produce.

Examples of products include meat, Examples of products include meat, eggs, milk, and wool.eggs, milk, and wool.

66

Animal ReproductionAnimal Reproduction Most animals are produced with Most animals are produced with

sexual reproduction. sexual reproduction. Sexual reproductionSexual reproduction is the union of a is the union of a

sperm and an egg. sperm and an egg. Two parents are required.Two parents are required.

• SpermSperm is the sex cell of male animals. is the sex cell of male animals. They are produced in the testes.They are produced in the testes.

• The The eggegg or ovum is the sex cell of or ovum is the sex cell of female animals. female animals. They are produced in the ovaries.They are produced in the ovaries.

77

Animal ReproductionAnimal Reproduction FertilizationFertilization is the process by which is the process by which

the union of a sperm and an egg the union of a sperm and an egg occurs. occurs.

It is also known as conception.It is also known as conception.• The union of the sperm with the egg The union of the sperm with the egg

occurs in the reproductive tract of the occurs in the reproductive tract of the female. female.

• The process of placing sperm in the The process of placing sperm in the reproductive tract of the female is known reproductive tract of the female is known as as inseminationinsemination..

88

Animal ReproductionAnimal Reproduction

• Natural inseminationNatural insemination occurs when a male occurs when a male of a species mates with a female of the of a species mates with a female of the same species. same species.

• Sperm are placed in the female reproductive Sperm are placed in the female reproductive tract by the male during copulation.tract by the male during copulation.

• CopulationCopulation is the mating process in which is the mating process in which sperm are ejaculated from the penis of the sperm are ejaculated from the penis of the male in the vagina of the female. male in the vagina of the female.

• Females must be receptive to males at a Females must be receptive to males at a time in the estrus cycle known as time in the estrus cycle known as heatheat..

99

Animal ReproductionAnimal Reproduction

• Artificial insemination is used in some Artificial insemination is used in some situations, such as with dairy cows. situations, such as with dairy cows.

• Artificial inseminationArtificial insemination is placing is placing semen collected from a male in the semen collected from a male in the female reproductive tract using female reproductive tract using equipment designed for the purpose.equipment designed for the purpose.

• Artificial insemination must be done Artificial insemination must be done when the female is in heat.when the female is in heat.

1010

Animal ReproductionAnimal Reproduction Once an egg has been fertilized, it Once an egg has been fertilized, it

becomes an embryo that attaches becomes an embryo that attaches itself to the uterus for nourishment.itself to the uterus for nourishment.

The female is pregnant. The female is pregnant. The embryo goes through a time of The embryo goes through a time of

development and becomes a fetus. development and becomes a fetus. The fetus develops to a stage where it The fetus develops to a stage where it

is born and can live outside the uterus.is born and can live outside the uterus.

1111

Sexual Classifications Sexual Classifications

Sexual classificationSexual classification is the condition is the condition of an animal based on its age and of an animal based on its age and sexual condition.sexual condition.

• It includes animals that are capable of It includes animals that are capable of reproduction as well as those that are not reproduction as well as those that are not capable of reproduction.capable of reproduction.

1212

Sexual ClassificationsSexual Classifications

An animal can be made incapable An animal can be made incapable of reproduction by removing the of reproduction by removing the ovaries or testes or altering the ovaries or testes or altering the condition of the reproductive condition of the reproductive organs so that they are no longer organs so that they are no longer fertile. fertile. • The animals are not capable of The animals are not capable of

conception.conception.

1313

Animals incapable of reproductionAnimals incapable of reproduction

• CastrationCastration is the process of removing the is the process of removing the testes from a male. testes from a male. It is a management practice used on young It is a management practice used on young

male animals. male animals. Castration eliminates unwanted breeding.Castration eliminates unwanted breeding. It also promotes growth and development of It also promotes growth and development of

young animals in more desirable ways with young animals in more desirable ways with food animal production. food animal production.

Castration may be done surgically or with other Castration may be done surgically or with other methods. methods.

1414

Animals incapable of reproductionAnimals incapable of reproduction

• NeuteringNeutering is the process of making a is the process of making a female incapable of reproduction.female incapable of reproduction. It is also known as spaying. It is also known as spaying. The ovaries of the female are removed The ovaries of the female are removed

or other procedures are used to render or other procedures are used to render the female incapable of conception. the female incapable of conception.

1515

Sexual ClassificationsSexual Classifications A number of terms are used to A number of terms are used to

describe the sexual classification of describe the sexual classification of animals. animals. • These terms vary by species, age, and These terms vary by species, age, and

gender. gender. • For example, a For example, a steersteer is a male bovine is a male bovine

castrated at a young age and before castrated at a young age and before sexual maturity was reached. sexual maturity was reached.

• Textbooks and references usually have Textbooks and references usually have lists of terms for the sexual classification lists of terms for the sexual classification of common species.of common species.

1616

SpeciesSpecies YoungYoung Mature Mature MaleMale

Mature Mature FemaleFemale

Castrated Castrated MaleMale

CattleCattle CalfCalf BullBull CowCow SteerSteer

SheepSheep LambLamb RamRam EweEwe WetherWether

GoatGoat KidKid BuckBuck DoeDoe WetherWether

ChickenChicken ChickChick RoosterRooster HenHen CaponCapon

HorseHorse FoalFoal StallionStallion MareMare GeldingGelding

Female – Female – FillyFilly

Male - Male - ColtColt

1717

What are some of the common breeding What are some of the common breeding

systems used in livestock productionsystems used in livestock production?? StraightbreedingStraightbreeding is mating animals of the is mating animals of the

same breed. There are several variations of same breed. There are several variations of this system. this system. Some of the most common are:Some of the most common are:

• Purebred BreedingPurebred Breeding — A purebred — A purebred is an animal of is an animal of a breed in which both parents of the animal must a breed in which both parents of the animal must have been purebred.have been purebred.

• InbreedingInbreeding is the mating of related animals. This is the mating of related animals. This increases the genetic purity of the stock produced.increases the genetic purity of the stock produced.

1818Inbreeding TypesInbreeding Types

ClosebreedingClosebreeding is is the most intensive the most intensive form of inbreeding, form of inbreeding, in which the animals in which the animals being mated are being mated are very closely related very closely related and can be traced and can be traced back to more than back to more than one common one common ancestor.ancestor.

1919Inbreeding TypesInbreeding Types

LinebreedingLinebreeding refers to mating refers to mating animals that are animals that are more distantly more distantly related and can related and can be traced back to be traced back to one common one common ancestor.ancestor.

2020

Grading UpGrading Up

Grading upGrading up is the is the mating of purebred sires mating of purebred sires to grade females. to grade females. • A A grade animalgrade animal is any is any

animal not eligible for animal not eligible for registry as a purebred. registry as a purebred.

• This is done as less This is done as less expensive way to improve expensive way to improve the quality of animals on a the quality of animals on a farm or ranch.farm or ranch.

2121

CrossbreedingCrossbreeding

Crossbreeding Crossbreeding is the mating of two animals is the mating of two animals from different breeds. from different breeds. • The resulting offspring is a hybrid. This generally The resulting offspring is a hybrid. This generally

results in improved traits in the offspring.results in improved traits in the offspring.• Superior traits that result from crossbreeding are Superior traits that result from crossbreeding are

called called hybrid vigorhybrid vigor or or heterosisheterosis..

2222

Estrous CycleEstrous Cycle The The estrous cycleestrous cycle is the phases in the is the phases in the

reproductive cycle between periods of reproductive cycle between periods of estrus.estrus.• These are the phases of reproductive These are the phases of reproductive

readiness in the reproductive system of a readiness in the reproductive system of a mature female. mature female.

• The cycle does not occur during pregnancy The cycle does not occur during pregnancy nor when a female is in anestrus.nor when a female is in anestrus.

• AnestrusAnestrus is the absence of cycling. It may is the absence of cycling. It may occur due to disease, not being of occur due to disease, not being of reproductive age, or other conditions.reproductive age, or other conditions.

2323

Estrous CycleEstrous Cycle

The estrous cycle is comprised of The estrous cycle is comprised of four phases. four phases.

The phases occur in a definite The phases occur in a definite sequence unless the female is sequence unless the female is pregnant. pregnant.

2424

Phases of the Estrous CyclePhases of the Estrous Cycle

• EstrusEstrus is the phase when a female is is the phase when a female is in heat. in heat.

• The animal is receptive to mating and The animal is receptive to mating and will stand for copulation with a male.will stand for copulation with a male.

• Females exhibit signs of heat. Females exhibit signs of heat. An enlarged vulva and a discharge from it are An enlarged vulva and a discharge from it are

signs. signs. Some females exhibit behaviors indicating Some females exhibit behaviors indicating

readiness for mating such as when a cow readiness for mating such as when a cow mounts another cow in the mating position.mounts another cow in the mating position.

2525


• MetestrusMetestrus is the phase following heat. is the phase following heat. Ovulation occurs during metestrus as do Ovulation occurs during metestrus as do

other processes that help maintain a other processes that help maintain a pregnancy should conception occur.pregnancy should conception occur.

2626

• DiestrusDiestrus is the phase in the estrous is the phase in the estrous cycle when the reproductive system cycle when the reproductive system assumes that conception has assumes that conception has occurred, even if it has not. occurred, even if it has not. Diestrus is several days long Diestrus is several days long

depending on the species of animal.depending on the species of animal.


2727


• ProestrusProestrus is the period following is the period following diestrus in which preparation is being diestrus in which preparation is being made by the reproductive system for made by the reproductive system for the next heat period and ovulation. the next heat period and ovulation. If conception has occurred, the estrous If conception has occurred, the estrous

cycle ceases until it is renewed after cycle ceases until it is renewed after gestation and parturition.gestation and parturition.

2828


• Animal producers can be more efficient in Animal producers can be more efficient in animal reproductive management if they animal reproductive management if they know the phases of estrous. know the phases of estrous.

• Careful observation by a trained producer Careful observation by a trained producer and records on reproductive cycles will and records on reproductive cycles will promote breeding to assure the production promote breeding to assure the production of young animals at the best time. of young animals at the best time. For example, cattle producers often breed cows For example, cattle producers often breed cows

to assure calving in the spring when pasture to assure calving in the spring when pasture grasses are beginning to grow. grasses are beginning to grow.

This allows a cow to produce maximum milk for This allows a cow to produce maximum milk for the nutrition and growth of the calf.the nutrition and growth of the calf.

2929

Reproductive Development of AnimalsReproductive Development of Animals

Animals of a species begin life as either Animals of a species begin life as either a male or female. a male or female.

Their development as a member of Their development as a member of their species includes reproductive their species includes reproductive development for their gender.development for their gender.• Reproductive development follows fairly Reproductive development follows fairly

definite stages and processes.definite stages and processes.

3030


Prepuberty is the stage of life of Prepuberty is the stage of life of a young animal before it is a young animal before it is capable of reproduction. capable of reproduction. • Sufficient development has not Sufficient development has not

been reached for an animal to been reached for an animal to reproduce.reproduce.

3131


PubertyPuberty is the stage when an is the stage when an animal reaches a level of sexual animal reaches a level of sexual development where it is capable development where it is capable of reproduction. of reproduction. • Puberty occurs in both males and Puberty occurs in both males and

females.females.

3232

PubertyPuberty• With females, the estrous cycle results in the With females, the estrous cycle results in the

release of mature eggs that can support the release of mature eggs that can support the mating, conception, and gestation processes. mating, conception, and gestation processes.

• With males, the animal is capable of With males, the animal is capable of producing viable sperm. producing viable sperm.

• Age of puberty varies with animal species Age of puberty varies with animal species and other conditions such as nutrition and and other conditions such as nutrition and health condition. health condition.

• Examples of when puberty is reached are: Examples of when puberty is reached are: cattle 8-12 months, sheep 5-7 months, and cattle 8-12 months, sheep 5-7 months, and horses 12-15 months.horses 12-15 months.

3333

GestationGestation

• GestationGestation is the period when a is the period when a female is pregnant. female is pregnant.

• The length of gestation varies with The length of gestation varies with species though it tends to be species though it tends to be consistent among members of the consistent among members of the same species.same species. For example, the gestation period is 155 For example, the gestation period is 155

days for ewes and 337 days for a mare.days for ewes and 337 days for a mare. The animal gives birth at the end of The animal gives birth at the end of

gestation.gestation.

3434

ParturitionParturition

• ParturitionParturition is the process of is the process of giving birth. giving birth. Hormones are produced to Hormones are produced to support the birth process and support the birth process and prepare for lactation.prepare for lactation.

3535

LactationLactation

• LactationLactation is the secretion of is the secretion of milk by the mammary glands of milk by the mammary glands of a female. a female.

• It is initiated by hormone activity. It is initiated by hormone activity.

• Lactation lasts for several Lactation lasts for several months following parturition.months following parturition.

3636

Mating BehaviorMating Behavior

Mating behavior is a part of Mating behavior is a part of reproductive development. reproductive development.

Both males and females of a Both males and females of a species exhibit mating behavior. species exhibit mating behavior. • With males, this includes libido With males, this includes libido

(desire to mate) and social status (desire to mate) and social status within a herd. within a herd.

• With females, receptivity to mating With females, receptivity to mating occurs during heatoccurs during heat..

3737

SummarySummary 1. What is the importance of animal 1. What is the importance of animal

reproduction?reproduction? 2. List the sexual classification of animals for 2. List the sexual classification of animals for

major species.major species. 3. What are the different breeding programs 3. What are the different breeding programs

used in your area?used in your area? 4. Describe the phases of the estrous cycle4. Describe the phases of the estrous cycle 5. How does reproductive development of 5. How does reproductive development of

animals occur?animals occur?

Documents

1 Unit B Understanding Animal Body Systems Lesson 7 Understanding Animal Reproduction