terms used in farm animal reproduction.pptx

Glossary

1. Terms used in animal reproduction Ovulation Ovulation occurs at the ovary surface and is the process whereby an oocyte (female germ cell) is released from the follicle.

2. Spontaneous ovulation I s the process where species go through menstrual cycles and are fertile at certain times based on what part of the cycle they are in. Species in which the females are spontaneous ovulators include cattle, sheep and humans.

3. Induced ovulation I s when a female animal ovulates due to an externally derived stimulus during, or just before, mating, rather than ovulating cyclically or spontaneously. Species where the females are naturally induced ovulators include cats, rabbits, goats and horses.

4. Fertilisation Fertilisation is the process in which the male gamete (sperm) fuses with the female gamete (ovum) to form a zygote, which, through cell division, becomes the embryo. In farm animals, fertilisation (conception) can only occur when the female animal comes on heat, ovulates and is mated or artificially inseminated.

5. Z ygote The fertilised egg’

6. Gestation I s the period between conception ( fertilisation ) and the birth of the young animal (parturition). It varies in length with the different classes of farm animal

7. Foetus During pregnancy, the embryo becomes implanted into the wall of the uterus and membranes develop around it. The placenta develops and enables nutrients and oxygen to pass from the mother to the growing embryo, which is now called a foetus .

8. The oestrous cycle The oestrous cycle is a sequence of events occurring in female mammals. The cycle is the number of days from the beginning of one heat period (oestrus) to the beginning of the next heat period. The oestrus cycle is controlled by hormones. Once puberty is reached, female farm animals come into heat at regular intervals.

9. The heat period I s the length of time during which the female farm animal is sexually receptive to the male farm animal. Once puberty is reached, female farm animals come into heat at regular intervals. It is only during the period of heat that the female allows herself to be serviced by the male. Heat occurs as a result of the large amount of the hormone oestrogen , produced by the ovaries, circulating in the blood.

10. Ovulation I s the release of an ovum from the ovary. It is closely associated with the heat period. It usually occurs during oestrus or shortly after it. Mating during this time can result in fertilisation and pregnancy

11. Oestrus synchronisation I s where female mammals are targeted to come into heat in a short period of time through the use of hormones. The benefits are that dairy and beef cattle can be managed with appropriate nutrition, without wasting feed costs. Further benefits are that a bull can be optimised during this time, expensive AI treatment could potentially have a higher success rate.

12. The phases of the oestrous cycle. Proestrus : Proestrus is influenced by oestrogen , which prepares the reproductive system for oestrus and stimulates the growth of ovarian follicles and the development of ova. Oestrus (the heat period): This phase is also influenced by oestrogen , which causes the female to be sexually receptive for mating. It may result in ovulation. Metoestrus : Ovulation may occur at the beginning of this phase. After an ovum has been released from its follicle, a corpus luteum develops. The hormone progesterone begins to be produced by the corpus luteum. Less oestrogen is released. Dioestrus : If fertilisation does not occur, the corpus luteum breaks down and there is a short period of inactivity before a new proestrus phase begins.

13. Signs of heat

14. Parturition Parturition (the birth process) occurs at the end of the pregnancy. This is the time when the female animal gives birth to her young. This process is influenced by hormones such as oxytocin and relaxin .

15. Stages of Parturition Just before parturition, the animal may become restless. She will look for a quiet area, and will try to urinate frequently. In cows, there is a thick mucus discharge from the vulva. Uterine contractions occur as a result of the secretion of the hormone oxytocin. The cervix and pelvic region dilate (widen) under the influence of relaxin . • The offspring is delivered through the birth canal. The placenta (afterbirth) is delivered shortly after the offspring.

16. The farmer or a farm attendant should always be present at parturition to help the animal. It may be necessary to: Remove mucus from the mouth and nostrils to enable the young animal to breathe easily Dry the young animal if the mother has not already done so Make sure that the umbilical cord is not wrapped around the neck of the young animal C ut the umbilical cord, using the correct procedures Make sure that the mother suckles the young animal soon after birth so that the young animal gets the colostrum (first milk after parturition). Colostrum contains antibodies that will protect the young animal from infection.

17. Kindling Kindling is the term used to describe the process of giving birth in rabbits. It takes place 30 days after a successful mating of the doe with the buck. About five days before the doe is due to kindle, she will carry straw around and build a nest. A nest box should be placed in the rabbit pen three days before kindling is due.

18. Farrowing Farrowing is parturition in pigs and takes place about 115 days after mating. Two weeks before farrowing, the mammary glands of the sow develop, the teats enlarge and veins supplying the udders become prominent. The farrowing process lasts 3–8 hours, with piglets delivered at 10–20 minute intervals. When all the piglets have been delivered, the placenta is expelled.