Gap Maternity Short

Gap Maternity Short

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Sustainable Livestock Productivity - Reproductive Prospectives and Advaced Technological Applications

Introduction

            India has approximately one billion animals for a billion humans. We need less animals to sustain our present productivity if proper gene propagation and animal reproduction methods used. Our per animal production is much less. Inspite of this weakness our per unit cost of production of livestock products is not only less but is economical. This is why, our livestock farming exists without any subsidy and has great potential to be sustainable. Thus, competitive economic livestock production systems are our strengths. Details of economics of goat management systems have been reviewed (Wani, 2002). Similar evaluation in other livestock species viz. Cattle, buffaloes and sheep do reveal positive trends. The improvements in our traditional and reproductive management of buffaloes have won us the first rank in world milk production. Our grains are however over shadowed by export restrictions to developed and developing countries except Bangladesh and Sri Lanka. Our poor zoo-sanitary conditions are responsible for it. Thus our first requirement in future is to provide sensitive, accurate and timely disease surveillance and diagnostics, so as to make our milk or meat surplus areas as disease-fre-zones. Per capita meat requirement as per ICMR recommendations is 25 gms per day. We produce at present only 9 gm per person per day. This critical gap abridgement needs more emphasis on enhancing meat production. These two priorities should be the main objectives of this review.

(2) Zoo-sanitation and bio-safety

            With production of 78 million tones of milk in 1999-2000, India ranks first in global milk production. It has Rs. 113 million worth milk products in export godowns. There are few buyers. Except Sri Lanka and Bangladesh none dares to import our cheap milk and meat productions, for fear of disease transmission. Our poor zoo-sanitary  conditions is our weakness. Our products fail to complete products from other countries, as their products appear to be safer. The lobbing by rich, media hippie world puts our livestock products at disadvantage even with our own Asian neighbours, whose bio-safety measures are more accurate and sensitive than us.

            The use of artificial insemination (AI), embryo transfer(ET) have helped in elite gene propagation. “Dolley” the super sheep is known and many more genetic clones are in offering. Today our concern is bio-safety of germplasm and the animal products. With high risk of new disease emergence all researchers are warned to use their materials with caution. The “mad cow disease” and heavy economic losses in U.K. and Europe are eye openers for all  of us. The future of gene technology lies in bio-safety and fulfillment of international zoo-sanitation regulations. Disease free zones need more emphasis than producing high  yielding livestock from disease infested areas. Thus safe and quality animal material (germplasm) and products is the slogan for tomorrow. Zoo sanitation certifications will demand more trained veterinarians.

(3) Gene propagation and utilization

            For production and utilization of elite gene pool of animals, we need to know our own resources, both biological and material. For example, increasing  meat/milk or fibre production from our small ruminants we need to know them better. We must analyse their gene pool both qualitatively and quantitatively as was done in goats( Gall et al., 1997) use DNA techniques. Once we know merits and demerits of our gene pool, could we preserve them or utilize them for further up-gradation. A small attempt of buck exchange in Ladakh and better use from identified tribes helped in the fine pashmina production, which awaits suitable markets. Mongolia crossed their pashmina goats with Russian “Don goats”. The quantity of pashmina increased but the quality reduced. We are fortunate that due to our criticism, J&K avoided introduction of Don goats in Ladakh, otherwise by now we would have lost the only quality “fine pashmina” of Kashmir (Wani et al., 195; Gall et al., 1997).

(4) Endocrinological advances 

            Ovarian oogenic and endocrine functions are interlocked via Hypothalamo-Hypophysial-Gonadal Axis (HHGA). The cyclicity and its behavioural overt and covert phase are instrinsic to these ovarian functions. The have been thus rightly named as “the Zeitgeber  or biological clock (Baird, 1987). The existence of feedback loops of ovarian steroids with respective gonadotrphin is biphasic phenomenon, where higher concentrations in blood have inhibitory or suppressive effects, low considerations have stimulatory effects (Barac Lough, 1973). Many reproductive mechanisms hang on changes in these ovarian steroids such as labour pains (Csapo, 1981), ovulatory failures (Sancheq-Crado et al., 1990). Interestingly these hormones interact to modify or sometimes antagonize each other. For example P4 appears to be potent antagonist of E2 at a combined ration  of 1:1 (Heap and Flint, 1987). The synergism ,agonistic and antagonistic actions of these hormones combinations are the basis for all reproduction manipulations viz.  Control of oestrus, ovulation, conception, gestation, fertility, infertility, contraception and or abortions. Fish and sheep ovarian extracts were tested to find out interclass sensitivity. It seems it is possible to tap huge fish ovarian extracts for intra and interpolation in mammalian ovary (Najar, 1999). Coming years will see more attempts to use such resources to avoid side effects from chemical and synthetic analogues of hormones.

5. Follicular atresia   

          GnRH- regulates gonadotrpin release from pituitary, but its continuous and prolonged use in natural from or as its potent agonist induces an inhibitory effect on ovarian steroidogenesis , follicular development and ovulation (Kledzik et al., 1978; Srivastawa et al., 1995) GnRH receptor gene encoding is expressed in the rat ovary (Kaiser et al., 1992). A new concept prevails today which postulates that an intrinsic GnRH system competes with receptor. Thus its biological response exist within the ovary. The follicular atresia is brought by this  intrinsic GnRH system (IGS) (Erickson et al., 1994) A new vision of autocrine and paracrine secretion of ovary vis-in-vis GnRH becomes evident.Future modulations in correcting reproductive failure involving hormone thereby needs rational understanding of all endocrine, autorine and related control mechanisms. Ovarectomized ewes when implanted with E2 and P4 implants were maintained in an artificial follicular phase. This speaks of an endocrine model compatible to a natural sequencing hormones of desired levels (Karsh and Evans, 1996).

6. Instrinsic GnRH system (IGS)

            Two theoretical  models called deterministic and permissive models have been put forth to explain of GnRH(Karsch et al., 1977).

Deterministic model

 

            Deterministic model envisages that a surge-like increase in GnRH is needed to induce preovulatory LH surge. This model befits animals whose LH release and ovulation is either time bound (Copulation) or signal dependant (cervical signal, rabbit and neural signal Central circadian pacemaker in rats refers).

Permissive models

            Permissive models explain GnRH in relation to ovulatory LH surge. Here feed back of steroids exert their influence on anterior pituitary gland. This is supported by evidences that LH surge continue in situations where GnRH secretion is apparently abolished. For example in monkeys with hypothalamic lesions, or in women with hypothalamic amenorrhea or congenital GnRH deficiency, normal LH surges (Martin et al., 1990)

7. Hormone Agonists/antagonists 

            Hormone antagonist or anti-hormone are those compounds or elements which prevent an endogenous hormones from exerting its biological efft(s) (Vanlook, 1988). These anti-hormone need to be safe i.e. free from side effects. The hormone antagonists in principal acts in 3 ways.

i)                  Inhibition of hormone synthesis

ii)                Neutralising hormone action by specific antibodies.

iii)             Blocking the receptors of the hormone/

Use of antagonists, agonists have demonstrated their role in ovulation control.

Their cow histamine-releasing activity (Fraser, 1981) support their wider use which needs further extensive studies. More details are reviewed (Najar, 1999).

8. Reproductive failures –GnRH mechanism. 

            The biggest problem in ovarian manipulation faced in the past was due to varied superovulatory response (Wani, 1984). The follicular atresia was postulated to reduce this constrain if induced adequately. As our atresia was postulated to reduce this constraint if induced adequately. As our understanding of (IGS) intrinsic GnRH system was poor them, we could not use it to overcome our problems. Now we know follicular atresia is related to this IGS (Erickson et al ., 1994) and therefore, our later manipulations incorporated GnRH became the subject of discussion. Estrogen alone can induce ovulation but for CNS (Central Nervous System) priming progesterone combination in desired ratio is essential (Evans et al., 1995). Thus future modulations in correcting reproductive failures needs a proper understanding of hormonal inter and intra polation with physical , chemical, biological and neuroendocrine secretion. Pheromones and other phycoemotional factors too need an analysis.

            In our experiments on infertility (anoestrus) in cows of Kashmir (District Budgam) we were puzzled to see better response with low doses (300 µg) of GnRH than the higher dose of 400 µg (Shah, 1996). We are unable to explain our results until the recent studies on permissive and deterministic models of GnRH action came to light (Karsch and Evans, 1996, Karsch et al., 1997).

9. Herbal – biostimulators

Pheromones, sires introduction effects, sensory reflexus and vast other stimulants increase receptivity as well as fertility in domestic animals. Sprays and herbal cure products will be in great demand to increase or decrease fertility in coming years. The use of stimulants or repellents as sprays and sprays and scents may be in need. Herbal cures for various reproductive wastage needs further research. The use of herbal products, fruits, nuts and medicaments in ancient Kashmiri culture after delivery, need to be looked  at. The Cichorium spp, saffron, Cofula anthemoides, Prunella vulgaris, Artemisa and other products in use during post delivery period needs scientific analysis.

The ovarian sensitivity decrease soon after parturition and its resurgence after 14 days in cows, 40 odd days in women and specific periods in other animals, reveal a lot which needs exploration to phase out various sequences of reproduction.

10. Corpora luteal biosensitivity

            Corpus luteum growth and development is the earliest pregnancy signal along with maternal recognition factors discussed (Wani, 1996). The corpus luteum development and receptivity to PGF2 alpha is now known. The ascending and descending corpora lutea are insensitive to PGF2 alpha. What makes them insensitive and what resurges their sensitivity need exploration. May be in future, CL insensitivity might have direct effects on survival of the conceptus. Does conceptus make CL more sensitive to PGF2 alpha? Or in other words, does the gravid CL and non-gravid CL behave similarly or differently toPGF­2 alpha. Many such questions vis-à-vis the ovarian morphology, uterine environment and behavioural patterns need to be studied and co-related to develop a manipulative and curative safe system. In some species CL of pregnancy in necessary till delivery, in others it is needed only till placenta develops. Its complete genesis and biostimulation and bioregulatory role are obscure and needs further research.

11. Dominant follicle dynamics 

            The dominant follicle dynamics may be in focus for ovulation control. Dominant follicle or would be bride at each ovulation appears around day 7 of cycle in women. It occurs much earlier on day – 1 to 0 in ruminants (cow, sheep, goats). This time point may be the focus to try future selective interferences in ovulation control. Antagonist use during this phase has shown decreasing levels of oestrogens in serum thereby indirectly hinting at dominant follicle alteration, as it is one of chief source of this hormone during this phase (Fraser, 1987). Dominant follicle in its sojourn to freedom and release at ovulation seems to attain some specific qualities. Why? It alone releases itself of bondage’s in ovary (Ovulation) and rest of its competitors are hindered through the process as atretic follicles. What makes this dominant follicle to attain these qualities among a vast pool of follicles needs further study. In coming 50 years one shall possibly understand and interlock a pre-determined messenger system triggering dominance in one or few follicles destined to become the new offspring of that species. This system when decoded shall offer new opportunities in controlling ovulation both for contraception (women) or augmentation (animals). New genepool of dominant follicles from dead high yielding animal ovaries would help to propagate and multiply the elite.

12. Development of conceptus – in vitro foetus

            The lean meat production needs more studies on development of conceptus. We know that prenatal development undergoes in three stages. During early pregnancy skeletal & nervous tissues grow, on priority. During mid-gestation the hind and fore-limbs develop. During late gestation muscular development along with peripheral extremities including hair develop. In order to increase lean meat production, research in needed to investigate relationship between hard and soft tissues. Maternal and foetal interactions needs a probe. Some basic studies 9Mufti, 1996) indicated prospects of manipulating lean meat production (Wani, 2001, 2002 a) by bio-stimulators during late gestation, which may help, the production of muscular lambs/kids at birth, besides, increasing birth weights. More details have been described (Wani, 2001, 2002a)          (Fig. 1-5). More studies in future are  needed to reveal the exact mechanism involved in critical transition of power control from maternal to embryonic genome. Application of recent techniques of reverse transcription, PCR and other may reveal the details (Schultz et al., 1990).

13. Slaughter house follicle pool

            A good number of our endangered species die in wild , where climatic conditions are hard and harsh. Under temperate climatic conditions dead bodies are entrapped in snow for long. It gives a hope to revive their follicular pool. Our studies on resumption of life using follicles from slaughtered sheep and fertilizing them with epididymal semen was an pioneering attempt in this direction (Wani, 1996) (Fig 6-8). The protein content of unfertilized ovum is around 100 mg in rabbit, 27 mg in mouse (Brinster, 1967,1971). This small genetic material needs extensive analysis to unveil vast information in its condans and anticodnas. Further ovum maturation or resumption of merosis is initiated during birth or shortly before birth and thus the pool of follicles remains fixed at birth. Therefore, foetal ovary has to be the subject of further manipulations especially in view of its immunological insensitivity (Guraya, 1985).

14 Gamete biosafety

            Bacterial counts in semen in unprecedented numbers effect semen fertility (Kher and Dholokia, 1985), The contaminational hazards have increased due to environmental pollution, water and air contamination. Above all the development of resistance of known bateria and other micro-organism to antibiotics (Gupta and Maurya, 1993). We have examined the semen of about 40 bulls maintained at the Frozen semen bank, Rambirbag, Kashmir for bacterial loads in semen and tested antibiotic sensitivity (Koul, 2002).

            Presence of bacteria in large numbers in semen, effects its quality and fertility (Kher and Dhololkia, 1985). The source of contamination of semen vary from inflammatory foci and lesions on penile apparatus, contaminations on equipments, appliances, diluters, extenders air and laboratory environment. These contamination hazards have increased with environmental pollution. Many bacteria having developed resistance of routine antibiotics used (Gupta and Maurya, 1993) in semen extenders has made inseminations more critical and vulnerable. More studies in this direction are needed to develop a bio-safe and infection free germplasm pool of frozen and fresh in future.

15. Foetal muscular development

            Genetics, hormonal and environmental factors influence foetal growth and development. The proper in-utero maturation and growth of foetus signify proper care and management of gravid nannies. The pre-natal development of foetus is exhibited at birth weight. The head and skeletal tissues grow and mature earlier, followed by fore and hind limbs. The muscular development of foetus occurs during late gestation. Thus, during early pregnancy nervous and skeletal tissues are having priority for nutritive requirements in-utero (Mufti, 1966). Maternal nutrition is important for growth and development of meat in off spring in-utero. Muscular growth stimulants may thus help production of quality meat lambs or kinds in future.

16. Foeto-maternal interaction

      The role of endometrial stromal cells during pre-implantation stage needs further research. Some studies on ultrastructure  of endometrium (Brinsfield et al., 1974) are still not sufficient to answer the questions. What is the role of immune cells and endometrial cells in building of the immunological barrier to protect the foetus. Foetal biology is a barren field of research in the world. After few initial steps by Dr. Moris Young in UK and Dr. Srivastava in India, only a scattered information is available on the subject (Wani and Buchoo, 1990; Mufti, 1960). Much is still to be unveiled. The placental hormone influence mammary development and milk production of the dam. This needs further research . Foetal membranes serve as chief source of nutritive exchange (Fig. 9). The arrangement of cotyledons, caruncles, positioning of single (Fig. 10) and twin (Fig. 11) conceptus, indicate complex mechanisms with common roots. These mechanisms of foeto-maternal  interactions and relationships emphasize proper foetal number diagnosis and corresponding materno-nutritional management strategies.

17.  Small ruminant reproduction

            There is a need of ovulation, pregnancy and foetal number detection by methods described (Wani, 1981, 1982; Wani and Sahni, 1980,1981; Wani and Buchoo, 1991, 1993). These reports demonstrated successful results ovulation detection, multiple ovulation predictions, early pregnancy and foetal numbers. The induction of multiple ovulation, in-vitro fertilisations, embryo collections, embryo collections, embryo culture, conservation, micromanipulation, splitting, cloning and sexing are some of the reproductive high-tech applications used to increase reproduction rates (wani, 1996; wani et al., 1990; Wani et al.,2000 a,b; Buchoo et al ., 2000). These techniques have put a little application under field conditions in small ruminants especially under extensive management system. However, their use has already revolutionized propagation of elite germplasm and can be used under buck mother farms to produce quality sires.

            The futuristic attempts in this direction should include in vitro post implantation and foetal development experiments. These future manipulations at organogenesis level may help to induce desired quality changes in offspring so that dressing percentages could be increased from present 40-50 percent  to 55-60 per cent or more.

18.  Reproductive management

The reproductive management strategies to enhance meat production could safely be divided into two kinds:

i.                   Traditional management : Animals are still managed under zero-input/migratory / tribal or extensive management system. Here the application of above described methods will be limited. The may indirectly help in this system by better sire availability.

ii.                 Modern management : Zero-grazing, stall-fed or semi-intensive, commercial small ruminant farming system may use the above methods more and more to produce high quality germplasm. They use variety of improved   reproductive   techniques     described    or     reported    (Wani,

1966; Wani et al ., 2000a; Wani et al .,1998; Mufti et al., 1997; Wani and Sahni, 1981; Wani et al., 1986, 1987, 1988; Wani and Buchoo, 1991; Buchoo and Wani,1991; Wani, 1989; Wani,1995; Wani, 1984a and b; Wani and Sahni, 1980a).

 

19.  Enhancement of fertility

            Desired fertility objectives have been discussed (Wani,2001). Increased prolificacy, early rebreeding, safe/clean parturition, set-time animal crop, elite gene introduction are some of the desired fertility enhancement goals. The constraints in achieving desired objectives in small ruminant livestock sector are the problems of inbreeding, reproductive losses (Wani, et al., 1980; 1994), pre-pubertal mating, indiscriminate or illicit mating, venereal diseases, nutritional and other stresses. These above referred factors reduce fertility status of our ruminants especially under trans-humane migratory systems.

            These constraints mentioned could be overcomed by adopting enhancement strategies (Wani, 2001), which include exchange of sires by tribal, Gujjar, Bakarwals and Chopans to reduce inbreeding. This could be ensured through legislature or forced castrations and introduction of sires from outside the flock. The pregnancy detection methods described (Wani, 1981) and lateron used extensively in J&K under farm condition (Wani et al., 1998; Wani, 1989) needs adoption as a routine in each flock for better care of offspring and dam.

20.  Nutritional bio-conversion

            The nutritional status of dams before mating could be improved by grazing them in pastures having 4-5 cm sward height herbage, yielding 1500 kgs and above of dry matter per hectare. Such pasturing shall increase ovulation. Reduced sward height pastures needs supplementation and introduction of nutritional block atleast 4-5 weeks before mating. Thus proper feeding 100 days prior to mating and parturition may help in healthy and heavy weight lamb/kid crop.  

            The pasture nutrient analysis and its supplementation as per requirement may help to avoid losses due to such deficiencies as cobalt, iron, phosphorus etc. which effect herbage and through herbage the animal health. The sire fertility test and use of disease free semen is the foremost requirement  towards increased productivity from small ruminants.

            The nutrition plays important role in maintaining fertility status of animals. With decrease in land for fodder cultivation, alternate sources and technologies to utilize agricultural waste for animal food is needed. The biotechnological intrervention in converting crop residues and other agri-horticulture waste into animal feed needs further research.

About the Author

Proffessor G. M. Wani is Director Extension Education, SKUAST – K, Shalimar Srinagar, J & K, India and Director SAMETI.

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