CHAPTER - 1
INTRODUCTION
Goat is one of the earliest discoveries of mankind in prehistoric times as
ready and easy source of meat and milk. For thousands of years, they have been
utilized for their milk, meat, hair and skin all over the world. Whether in cold arid
uphill or hot arid deserts or hilly tracts of mountains or ravines constituted of
leached soil, goats have survived and sustained the poor people. Goat is a multi
functional animal and plays a significant role in the economy and nutrition of
landless, small and marginal farmers in the country. Goat rearing is an enterprise,
which has been practiced by a large section of population in rural areas. Goats
can efficiently survive on available shrubs and trees in adverse harsh
environment in low fertility lands where no other crop can be grown. Around the
world, more people eat Chevon (goat meat) than beef.
Goat husbandry is an important source of livelihood for the rural poor,
particularly for women, landless and marginal farmers living in the interior areas
who do not have other means of survival. Goat is ideally suited for the poorest of
the poor, because of short gestation period, low risk capital investment and low
cost of maintenance. With the growing demand for livestock products, goat
husbandry has become an attractive activity. Thus, goat population is increasing
where cattle and buffalo are not able to contribute to the rural economy. As goat
has fulfilled a most useful task in supplying a part of human population with milk,
meat, hair, leather and other byproducts like manure for agriculture use, it is one
of the friendliest creations of nature. The ability to grow at the rate with low input
and economical production of milk, meat, skin, fiber and manure , make it one of
the most important species of livestock.
Goat (Capra hircus) remains an important factor, in the national economy
and plays a significant role in Animal Husbandry sector. This is because of their
high prolificacy to recover flock size, much less housing requirement and
management problems with goats. Rearing of larger animals like cattle and
buffaloes is becoming more and more difficult every day. Smaller animals like
goats, which have no specific demands, offer a benefiting economy in situation in
producing milk and meat. Goats are proved to be a great boon to poor and
landless laborers or marginal farmers. There is much less risk in goat farming,
especially in drought prone areas where large mortality occurs due to frequent
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drought. The short generation interval of goats makes it possible to increase
productive life more rapidly than cattle. Their small size and relatively low
individual price bring them within the capacity of low income group. Due to their
immense contribution to the poor people economy, goat justified its designation
as “the poor man‟s cow.”
The better understanding of reproductive tract in goat is essential to
achieve greater success in conception rate and fertilization for having higher
percentage of kidding. The problem of fertility and sterility have always attracted
considerable interest which has been mainly directed to the reproductive tract
organs like uterus, ovaries and oviduct. In mammals, fertilization occurs in the
oviduct which is a dynamic muscular tube that undergoes cyclic variations in its
functional epithelium. The interaction of gametes and the subsequent fertilization
is a highly regulated process. Long and extensive series of coordinated events
have to take place both during the production and the maturation of gametes to
guarantee their successful interaction at the site of fertilization. The success of
fertilization and early embryo development in mammals is dependent upon the
oviduct providing a satisfactory environment, which facilitates sperm transport
and capacitation, fertilization and embryo cleavage (Hollis et al. 1984). The
understanding of functional disturbances leading to sterility and infertility is
possible on the basis of studying the cyclical changes in the female reproductive
tract.
The oviduct has many roles in the process of natural conception in goat.
The major two being retrieval of the oocyte released by the ruptured ovarian
follicle and facilitation of final maturation of the gametes. Both the sperm and
oocyte are transported in the oviduct to the site of fertilization and meet within a
well-defined time limit. The environment in the oviduct assists physiological
maturation of the spermatozoa and the ova and provides the zygote with the
appropriate nutrition for growth and development by secreting multiple
substances. As the mammalian oviduct plays an essential role in the reproductive
physiology in transport of ova, the spermatozoa and the early embryo, the
success of fertilization and early embryo development in animals is dependent
upon the oviduct.
The oviduct is an active secretory organ which secrets oviductal fluid
synthesized by the oviductal epithelium. The oviductal fluid provides a necessary
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environment for various reproductive processes. The secretory components of
the oviductal fluid are likely to have an important influence on intraluminal events,
such as final maturation of gametes, their fertilization and early development of
embryos. To improve the reproduction in goat, the better understanding of the
ultarstructural differences in relation to the functions that occur in the oviduct
during follicular and luteal phases of estrous cycle in goat is required. The
detailed morphological knowledge of oviduct may not only improve treatment of
its anatomical and physiological disturbances but also provides a better empirical
basis for its in vitro counterpart. As there is close relationship between cyclical
changes in the reproductive organ and fertility in animal, ultrastructural study of
oviduct in particular will help to correlate the importance of cyclical as well
regional variations in the oviduct with the fertility.
Information on cyclical changes and regional variations in the oviduct
would aid in better understanding of the events of reproduction in goat. Hence,
the aim of the present study is to examine the normal cyclical as well as regional
variations in the ultrastructure of oviduct of adult goat with the following
objectives:
1.
To study the histology of the infundibulum, ampulla and isthmus parts of
oviduct in follicular and luteal phases.
2.
To study the histochemical changes in the infundibulum, ampulla and
isthmus parts of oviduct in follicular and luteal phase.
3.
To study the ultrastructural changes in the infundibulum, ampulla and
isthmus parts of oviduct in follicular and luteal phase.
4.
To correlate the observations with the functional significance on the basis
of ultrastructure of oviduct in follicular and luteal phase.
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