Cattle Reproduction

Introduction Reproduction is the process by which animals produce offspring for the purpose of continuing the species. The process of reproduction begins with copulation, which is the mating of a male and female of the species. Sperm cells from the male are deposited in the female reproductive tract and try to unite with an egg cell. When fertilization (a sperm cell and egg cell unite) occurs, an embryo begins to develop. The embryo attaches to the wall of the uterus where it is protected, receives nourishment, and develops. When the new offspring reaches the end of the gestation period, it is delivered from the female reproductive tract in a process called parturition.

Hormones Male Female Testosterone- critical for sperm development Estrogen- critical for follicle development Progesterone- sustains pregnancy and inhibits new follicle development Relaxin- causes ligaments around birth canal to relax Oxytocin- causes milk letdown

Structure and Function of the Male Reproductive System

The major functions of the male reproductive system include: Production, storage, and deposition of sperm cells, Production of male sex hormones, Serve as passageway for expelling urine from the urinary bladder.

Male Reproductive System Testicles- Site of sperm production and testosterone synthesis Sperm contain ½ of genetic makeup Epididymis- Sperm storage and maturation Scrotum- Protects testes and regulates temperature

Male Reproductive System Vas Deferans- Transports sperm from epididymis to urethra Urethra- tube inside of penis transports sperm or urine exterior Penis- organ of copulation

Scrotal Circumference Gives an indication of a bull's ability to produce sperm and is related to younger age at puberty. Breeds differ somewhat as to scrotal circumference, but 32 centimeters is generally accepted as the minimum size for yearling bulls to be sound breeds.

Secondary male characteristics include coarse hair, horns that are long and large at the base, a deep voice, and pronounced muscularity. Photo from IMS.

Structure and Function of the Female Reproductive System

The functions of the female reproductive system include: Produce egg cells (ova), Serve as receptacle for the penis during copulation, and House and nourish the fetus until parturition.

Female Reproductive System Ovaries- Produce egg Egg contains ½ of genetic makeup Oviducts- Site of fertilization Transport embryos to uterus Uterus- Site of embryonic development during gestation

Female Reproductive System Cervix- Connects uterus and vagina Serve as barrier during pregnancy Vagina- Female organ of copulation at mating Opening of bladder Vulva- External opening of reproductive system

Terms of Reproduction Puberty- Age at which reproductive organs become functional Female- Reproduction process occurs within Estrous cycle- Repetitive cycle occurring when pregnancy does not Estrus- “Heat” or receptivity to mating Fertilization- Egg & Sperm unite Gestation- Length of time of pregnancy Parturition- Act of giving birth

Age of Puberty Estrous Cycle Cattle: 6 to 12 Months Cattle: Polyestrous (cycle throughout year)

Duration of Estrus Cycle Length of Estrus Cycle Cattle: 19 to 23 Days Duration of Estrus Cycle Cattle: 12 to 18 Hours

Signs of Estrus Swollen vulva Mucous discharge Restless behavior Female receptivity to male Visually active mounting

Gestation Length Cattle: 283-285 Days

Signs of Parturition Distended abdomen Mammary development & milk secretion Swollen vulva and relaxed pelvic ligaments Mucous discharge Relentlessness and separation from group Labor and Contractions

Signs of Parturition Appearance of placental membrane Expulsion of fetus Expulsion of placental membrane Bonding behavior of offspring and mother (will vary between species)

Transfer of Sperm Two different ways Let the male and female naturally engage. Male seeks out female in Estrus All controlled by male and female interaction Artificial Insemination (AI) Human transfers semen past female cervix Human is in control of male product and female interaction No contact between male and female

Artificial Insemination https://www.youtube.com/watch?v=R6fYyxs_lDE

Artificial Insemination (AI) Pros Conception rate is high Extends use of superior males One ejaculate can fertilize many females Reduce incidence of venereal diseases Individual straw per female Improves record keeping and mgt. Know exactly who the father is Can accelerate genetic improvements Conception rate is high Extends use of superior males One ejaculate can fertilize many females Reduce incidence of venereal diseases Individual straw per female Improves record keeping and mgt. Know exactly who the father is Can accelerate genetic improvements

Artificial Insemination (AI) Cons Need to know Estrus Cycle of animal Cost intensive Pay for someone to AI animals