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Introduction
In the year 1996 the total goat population in Pakistan was 41166,000 heads, while in Sindh it was 9734,000 heads.
In the year 1999-00 total goat population in the country was 47426,ooo heads, while the male population, one year and above was 6010,000 heads, the female one year and above was 25755,000 heads and young stock less than one year was 15661,000 heads.
In the year 1999-00, in Pakistan the gross production for milk from goat was 31,804,000 tonnes, while goat milk consumption was 25,566,000 tonnes.
In the year 1999-00 in Pakistan the goat meat production was 218,000 tonnes/million, goat skin production was 23.3 million No., goat hair production was 18,000 tonnes.
In the year 1999-00 in Pakistan the total fodder production was 2,64,900 hectares out of which in Sindh was 365,700 hectares. The total fodder production in Pakistan was 22.7 per hectare in tonnes, out of which in Sindh ,fodder crop production was 25.0 per hectares in tonnes.
General
The goat is a source of meat, milk, skin and fibre . Cross breeding among: Angora for Mohair production, Saanen, Alpine, Logenberg, Boee, Anglonubium, for milk and meat, are common practice.
If we improve environment, management, nutrition, selection of breeding and disease control .We can improve the economics of goat farming. Although improvement in reproductive efficiency , will increase the economic viability of goat enterprise. The reproductive efficiency depends on the length of the duration of pregnancy, litter size, embryo/foetal development , survival viability , growth of new born, suckling period, puberty age and duration of reproductive life. These methods can be improved by the use of modern reproductive tools which results into more kids per genetically superior bucks and does. These modern tools are describe as under:
Synchronisation of oestrus/ovulation in cyclic (Oestrus) goats:
Synchronisation of oestrus/oestrous cycle is a technique, which is used to bring large number of animals in a flock into overt heat at the predetermined time. The technique offers an opportunity to increase the efficiency of animal production in different ways. The benefits of heat synchronisation in goats are as under:
- a - It reduces the time needed for detection of oestrus.
- b - It helps in conjunction with a procedure for controlling the time of ovulation, to permit insemination on a predetermined schedule.
- c - It enables the feedings of goats in to uniform groups.
- d - It helps in synchronising breeds to shorten the duration of kidding in a flock.
- e - It reduces the mortality at the time of parturition by avoiding breeding during extreme seasons.
- f - It helps in reducing the neonatal mortality.
- g - After successful control of breeding to permit weaning, fattening and marketing of uniform group of animals.
By the help of control breeding, it bring proper weaning, fattening, growth,uniform in the herd, which provide better market price.
- h - This help in the use of embryo transfer technique.
Progestogens alone and progestogen + gonadotropin in , have been used for a long time. Recently prostaglandin and its analogues have been found very effective for synchronisation of oestrus. Keeping males with the females to induce synchronised oestrus and ovulation also used. Oral, subcutaneous, intra-muscular or intra-vaginal routes of administration are used.
Attempts to synchronise oestrus in Barbari, Black Bengal and Jamunapari does by administering progestogens, progestogen + gonadotropin in combination, and prostaglandin by using different routes (Oral, S/C, 1/m and intra-vaginal pessaries). Melengestrol acetate (mGA), used @ 0.15 mg/animal for 16 days in Barbari and Black Bengal goats, used by the scientists of I.V.R.I and C.I.R.G., synchronised 80-95% animals within 4 days of feeding. The fertility of the heated goats was not affected. Research is needed to find out a cheap, simple and effective heat synchronising technique.
Induction of oestrus/ovulation in acyclic (anoestrus) goats:
Delayed puberty and prolonged lactation and seasonal anoestruses in goats ultimately increases the age , at first kidding and the inter-kidding period, resulting into low life time production. Productivity in goat can be increased if the age at puberty and seasonal/lactation anoestrous period can be reduced. The use of inducing oestrus in anoestrous females increase the overall production efficiency. Induction of oestrus/ovulation in anoestrous goats can be accomplished by the use of gonadotropins and steroid hormones . Progestogesn alone and/or in combination and FSH and oestradiol for induction of oestrus in anoestrous Barbari, Black Bengal and Jamunapari goats was tried. An oestrous induction rate of 80-90% and a conception rate of 90% achieved by the use M G A @ 0.15 mg/animal for 16 days. This helps in increasing the reproduction life of goat.
Synchronisation of oestrus/ovulation in cyclic (Oestrus) goats:
Synchronisation of oestrus/oestrous cycle is a technique, which is used to bring large number of animals in a flock into overt heat at the predetermined time. The technique offers an opportunity to increase the efficiency of animal production in different ways. The benefits of heat synchronisation in goats are as under:
Superovulation:
Goat is the main source of meat. To get maximum number of kids, superovulation becomes necessity for increasing the overall fertility of the goat.
The objective of superovulation is to increase the yield of viable ova.
Several methods are used for inducing superovulation in goats. These are:
- a - Practice of flushing for some weeks before mating.
- b - Selection based on litter size.
- c - Use of hormones.
The use of hormones like: gonadotropins of pituitary origin (FSH and LH) or from the serum of pregnant mares (PMSG) ,are used as superovulating hormones. Gonadotropins in combination with progesterone or prostaglandins are used for induction of superovulation in goats.
Artificial Insemination
The artificial insemination is a successful technique in goat production, but its depends upon the understanding of applied reproductive physiology like selection of breeding goats, semen collecting method, frequency of semen collection, semen evaluation, diluents, dilution rates, optimum number of live and normal spermatozoa per inseminating goats, oestrous behaviour, stage of heat and insemination technique.
Sexual maturity in males.
Sexual activity in male is determined by placing them with oestrous female daily during morning and evening hours from the age of 6 months and onwards. Males showing active courtship tendency for sexual mount or natural service are separated from the rest of flock, while remaining males given further chance for expression of sexual desire, till the majority have shown complete sexual mounting.
Training of goats.
Sexually active goats should be trained for semen ejaculation in artificial vagina, daily, during morning hours by exposing them to an oestrous female fixed in a service crate.
Methods of semen collection.
Artificial Vagina (A.V) and electro-ejaculation are the most common accepted method for semen collection of goats . Artificial Vagina ( A.V.) method is being used as universal method for routine semen collection, whereas electro-ejaculation is generally used for collecting semen from untrained and valuable sires incapable of service. Good quality semen sample from breeding goats be made by collect semen once daily from native and half breeds and once or twice is quick succession (3-5 minutes) after every alternate day from exotic and higher cross-bred goats .
Semen evaluation.
Irrespective of semen collection procedure and frequency of semen collection, each ejaculate is examined for its quantity and quality in terms of volume, colour, consistency, motility, sperm density, total sperm number per ejaculate, per cent live/dead and normal/abnormal spermatozoa. The parameters are positively correlated with fertility. A good quality semen is cream coloured with thick consistency containing excellent wave motion. Sample containing with less than +4 motility, 3000 million sperm density and 80 per cent live spermatozoa should not be used for breeding purposes.
Dilutors and dilutions rate semen.
Immediately after collection and physical evaluation, semen samples are diluted with a suitable diluent like processed cow milk, egg yolk citrate glucose. Dilution rate is adjusted in such a way that a minimum of 60-80 million live and normal spermatozoa are available per inseminating dose (0.1 ml). This is easily met with dilution rate of 1:1 to 1:5 depending upon the sperm density of semen sample.
Preservation of semen.
Goat semen are stored successfully up-to 48 hours at 4-7°C with satisfactory sperm motility and fertility. Semen preservation by this procedure done carefully the entire cooling process be completed in 1.5 to 2 hours time.
Frozen semen.
Long term storage of goats semen become possible through deep freezing technique. Milk tris and egg yolk citrate glucose diluents containing glycerol as cryoprotective agent are suitably used as extender for freezing buck semen either by straw or pollet method. Straw method is more common. Straws filled with diluted semen and frozen over liquid nitrogen vapour can be stored for years in liquid nitrogen (-196°C). Post-thawing motility and fertility of frozen goats semen is relatively lower than the freshly diluted semen.
Detection of heat.
Oestrous goats in a breeding flock are detected by parading an active teaser/approned goat for about half to one hour daily, during morning and evening hours. Females allowing male to be mounted quietly should be separated from the flock. Oestrous goats detected during evening and morning hours should be inseminated twice in same oestrous.
Insemination technique.
Insemination is applied by lifting the hind legs of females at an angle of 60° from the ground. Locate the split like opening of the cervix with the help of sterilised glass speculum lubricated with liquid paraffin and deposit the semen over opening of the cervix with the help of inseminating pipes fitted with rubber bulb at the top. Remove the speculum and pipette together.
Fertility.
Embryo transplantation.
Embryo transfer, it refers to a technique by which embryos are collected from a female called the donor and than transferred, for development, to another female known as the recipient. This technique permits exploitation of superior female genotype, giving more off-springs from the same genetic donor than would arise under normal conditions of breeding.
In order to make the technology economically viable and sound. These suggestions are as under:
- a - Development of a simple non-surgical embryo collection and transplantation technique.
- b - Oocyte and embryo culture.
- c - In-vitro fertilisation.
- d - Long-term preservation of embryo under liquid nitrogen.
- e - Import of exotic germ plasma in the form of embryo.
- f - Production of kids of desired sex.
- g - Production of identical kids.
- h - Production of chimera.
- i - Production of hybrids.
- j - Production of clones of genetically superior animals.
A number of tests are used for detecting pregnancy at en early age. The choice of the technique depends on the species, stage of gestation, cost, accuracy and speed of diagnosis.
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No.
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Technique Used
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Description
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a)
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Non-return to oestrus.
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Post breeding/insemination non-return to oestrus gives an idea of pregnancy setting. During the breeding season, most of the animals return to oestrus within 17-23 days after fertilisation failure. At the end of breeding season, non-returns to oestrus are no longer use to defect pregnancy.
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b)
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Rectal palpation.
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Not possible in goat due to small size of pelvis.
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c)
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Visual assessment.
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Visual assessment through abdominal blotment shows advance stage of pregnancy.
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d)
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Laparotomy.
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Needs surgery. It gives 90-95% accuracy in goats of 5 weeks gestation.
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e)
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Laparoscopy/Endoscopy
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Presence or absence of pregnancy can be detected by direct observation of the uterus and ovaries through laparoscopy/endoscopy. Pregnancy can be detected at 40 days of gestation in goats.
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f)
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Radiography.
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It has limitation due to it can only be performed in a hospital.
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g)
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Ultrasonic technique.
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It is good and produce immediate results and can be adopted for field use.
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h)
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Vaginal cytology.
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It is impracticable under field conditions pregnancy diagnosis. Although pregnancy can be detected up-to 95% of animals at 40 days of gestation.
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i)
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Hormonal assay.
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This test is based on the level of pregnancy dependent hormones in blood, milk or urine radio immunoassay and competitive protein binding and ELISA technique used for the detection of hormone. With this technique pregnancy is diagnosed at earlier stage showing accuracy of 95%.
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j)
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Administration of hormones.
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Costlier with physiological side effects, it is accurate and detects pregnancy at an early stage.
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The best way of diagnose pregnancy with 60-100% accuracy after 30-60 days post conception done with the help of ultrasonic equipment. This technique is simple and can be applied at field. conditions with nominal price.
Induction of parturition.
This technique is used for induction of parturition, must be compatible with the survival and the normal development of the new-, without deleterious effects on lactation and on maternal behaviour. The various chemicals used for this purpose are cortico-steroid, oestrogens and prostaglandins. Vetesterol alone, vetesterol + oxytocin, dexamethasone alone and dexamethasone + vetesterol used at full term as well as 3-4 days before term in goats at CIRG.
Infertility problems.
Infertility problem in goats is caused due to various reasons. These are as under:
Infertility in males.
Infertility in males is an abnormalities of testes. The main abnormalities of the testes are: testicular atrophy, testicular degeneration, cryptocchidism, orchitis, epididymitis etc. A male suffering from any of the diseases show inability to serve the female and absence of sperm in the ejaculate.
Genital tract of a male can be infected with many different bacterial, viral, and chlamydial agents. Brucellosis is one of the major bacterial infection, which results into infertility in male this disease can be transmitted from one male to other male through copulation with female previously served by infected male, Animals suffering from such disease should be segregated immediately. Treated by antibiotic like chloromycetin and aureomycin.
It can also occurs due to nutritional deficiency like protein, phosphorus, copper, iodine and vitamin A leads to retarded sexual development, delayed puberty and low level of semen production resulting infertility.
Infertility in females.
In females, the problems of infertility are anoestrus, repeat breeders, embryonic mortality, genital defects and abortions.
Anoestrus.
Repeat breeder.
Is one which return to service repeatedly after being bred to a fertile male. These are two reasons for this like fertilisation failure and early embryonic mortality. This also happen due to genital tract abnormalities, besides infections, hormonal disbalances, hereditary and managemental factors. Treatment is infra-uterine injection of streptomycin before service. Sometimes tonophosphan injections on alternate day for 5 days also show improvement.
Infections of genital tract.
Genital tract of goat can get infection with bacterial, viral, mycotic and chlamydial agents. Some of them are potential pathogens and infection with them results in abortion in pregnant animals and may subsequently lead to infertility. These infectious diseases are common like: Brucellosis, Vibriosis, Chlamydial abortion.
Brucellosis.
In Brucellosis, abortion takes place between third and fourth month of pregnancy. In such case vaccination of all female kids at 6-12 months of age, at least one month or more, before the first breeding.
Vibriosis.
It is not common in goats although abortions occur in late stage of pregnancy.
Salmonellosis.
It is an acute contagious disease characterised by metritis and abortion. Abortions occur during the third trimester of pregnancy.
Foot and Mouth Disease.
Food lesions occur with bacterial infection. The infection of foetus with virus results in death of the foetus and animal becomes infertile.
Chlamydial abortion.
It is viral disease. Among the pregnant animals, it causes abortion.
Mycoplasmosis.
Mycoplasma infections cause abortions which lead to infertility.
Nutritional deficiency.
The deficiency of protein, minerals phosphorus, cobalt, manganese, copper causes infertility problems.
Conclusion.
The modern reproductive methods helps in having a more kids in life-time, reduced motility, healthy kids, genetically superior breeds. This way it helps to increase the economic benefits of goat farming.
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