eBook Chapters

12.1 Introduction

Allowing certain plants from the population to reproduce, while barring others, comprises selection. This permission for reproduction may be granted by nature or by the plant breeder. In the other words, both nature and breeder exert selection pressure. Natural selection operates through differences of fertility among the adult individuals of parent generation as well as through differences of viability among the individuals of offspring generation. Artificial selection, i.e., the selection from action of the plant breeder in the choice of parents, produces its change of gene frequency by separating the adult individuals of parent generation into two groups, viz., the selected and the discarded, that differ in gene frequency. So, selection simply implies the retaining of desirable types or culling of unwanted or undesirable types.

Combining Ability Estimation
Crosses made in a definite fashion are a prerequisite for combining ability estimation. Estimated by half-sib (GCA) and full-sib (SCA) mating. Various steps like parent selection for crosses, performing crosses, their evaluation, and interpretation are involved while estimating of combining ability. For analysis of crosses, biometrical techniques like diallel analysis, partial diallel, and Line x tester analysis are used. If GCA variance is higher than SCA variance the importance of AGA & parent selection will be effective for the improvement of such traits. If SCA variance is higher than GCA variance there is importance of NAGA( dominance & epistasis) & Heterosis breeding may be rewarding. If GCA=SCA variance then AGA & NAGA are equally important in the expression of character, In this situation reciprocal recurrent selection may be adopted for population improvement.
Selection for GCA
General combining ability (GCA) is the average value of the inbred line based on its behavior in crosses with other lines. The mean performance of the line is expressed as deviation from the mean of all crosses.GCA is owing to the activity of genes which are largely additive in their effects as well as additive × additive interactions.

The selection of individual animals from a group is very important in a livestock farming business. While creating a herd, every farmer should buy animals from a trustworthy disease-free herd and learn as much as they can about the animals. Once the herd is established, the selection of gilts and boars for replacement in the breeding herd should be based on type and performance. The following are important criteria to consider while creating a healthy sow herd:

• Size of litters
• Strength and vigour of litters
• Milking ability
• Temperament

One of the objectives of experiments in cultivators’ field is to test technology for adoption in a targeted area i.e. NARP Zone, or a district. In that case interaction between district x treatment within a zone or between blocks x treatment within a district should not be significant. If the targeted area is a district, an experiment in cultivators’ fields must occur in at least two blocks. Also, if the targeted area is a zone, an experiment should occur in at least two districts in order to estimate interaction.

Analysis of cultivators’ field experiment

The on-farm trials were conducted in 25 villages on kharif rice during 1992-93. The treatments viz. T1-Farmers’ practice with local variety, T2-Farmers’ practice with improved variety, T3-Farmers’ practice with improved variety +recommended fertilizer and T4-Improved practice with improved variety +recommended fertilizer. Farmers level of NPK fertilizer was 40:0:0 and local variety was Suzata while recommended NPK fertilizer was 80:40:20.

General Selection Procedures for Dairy Breeds
Selection of Dairy Cows
Selecting a calf in calf show, a cow in cattle show by judging is an art. A dairy farmer should build up his own herd by breeding his own herd. Following guidelines will beuseful for selection of a diary cow. Whenever an animal is purchased from cattle fair, it should be selected based upon its breed characters and milk producing.
History sheet or pedigree sheet which are generally maintained in organized farmsreveals the complete history of animal.The maximum yield by dairy cows are noticed during the first five lactations. So generally selection should be carried out during First or Second lactation and thattoo are month after calving.?Three successive complete milkings has to be done and an average of it will givea fair idea regarding production by a particular animal.
A cow should allow anybody to milk, and should be docile.?It is better to purchase the animals during the months of October and November.?Maximum yield is noticed till 90 days after calving.

Choosing the appropriate construction materials requires evaluating their properties, cost, availability, and how well they suit the particular project. Common materials include concrete, steel, bricks, wood, stone, glass, and various plastics. Key specifications often considered are strength, durability, fire resistance, and environmental impact.
MATERIALS OF CONSTRUCTION FOR TRADITIONAL GREENHOUSE
Traditional greenhouses are built using a variety of materials that ensure durability, insulation, and protection for plants, while also allowing sunlight to penetrate. The selection of materials depends on factors such as cost, climate, and the greenhouse’s intended purpose. Here are some of the common materials used in constructing traditional greenhouses:
1. Wood: Wood has been a traditional and widely used material in greenhouse construction due to its affordability and ease of use. Treated wood, such as cedar or redwood, is commonly chosen for its resistance to decay and insects. Wood offers good insulation and stability, making it suitable for different climates.
2. Galvanized Steel: Steel frames provide exceptional structural support and are known for their strength and durability. Galvanized steel is coated to prevent rust and corrosion, extending its lifespan. Steel frames are capable of withstanding heavy loads and harsh weather conditions.
3. Aluminum: Aluminum frames are lightweight and resistant to corrosion, making them a favored choice for greenhouse construction. They are easy to assemble and require little maintenance over time.
4. PVC Pipes: PVC (polyvinyl chloride) pipes are cost-effective and simple to work with, making them ideal for smaller or temporary greenhouses. They provide a basic, lightweight framework that is easy to assemble.

Proper records can be maintained and individual performance can be noted.

Disadvantages: A number of males should be maintained which is not economical.

Advantages of polygamous mating: Economical because 1 male can be used for 4-5 females. We can use postpartum estrus effectively.

Immediately after parturition after 7 days they come to heat. Breeding can be done 7 days after parturition after separating the young ones. [Weaning age 21 days]

But this is usually not followed because the number of young ones born reduces subsequently.

Disadvantages: Proper records cannot be maintained.

Selection is a phenomenon of giving preference to certain individuals in a population to reproduce over other individuals that are deprived of the opportunity to reproduce. In common parlance, it is the process to choose individuals from the herd that are going to produce the next generation and influence the performance of the herd. Performance of a herd is guided by the genes of the parents. In a herd, males give rise to more off springs and hence selection of males is an opportunity to boost cattle husbandry. The contribution of males to the inheritance of polygenic traits is equal with that of females. Hence, it is central to pay equal emphasis while selecting males and females. Selection of sire is more important than dam selection due to numerous reasons. The first reason is that a sire produces more numbers of progenies compared to one dam. Since a sire is called “half the herd”, it determines the performance of the herd. Modern initiatives like artificial insemination and frozen semen technology has further extended the use of sire and highlights the importance of sire selection. Artificial insemination has allowed the superior traits to reach different corners of the globe and this has benefitted the present generation at large. Frozen semen technology together with artificial insemination is milestone to the field of genetics and breeding. It is now possible to

Seed is defined as a ‘matured ovule’ or a reproductive unit formed from a fertilised ovule consisting of an embryo, food store and protective coat. These essential constituents are common to all seeds in different groups of seed bearing plants. The knowledge of seed morphology is essential for artificial regener ation as it can influence the collection, processing, storage and treatment of seeds. The external and internal morphologies of seeds are stable. Therefore, they provide reliable criteria for the positive identification of unknown seeds.

Importance of Tree Seed

Farmers have been growing trees for different purposes for thousands of years. Tree species that are grown to provide more than one significant function are called multipurpose trees. These functions may be productive such as producing fuelwood, timber, fibre, fodder, food, medicine, etc. and/or protective such as soil conservation, shade, shelterbelt, microclimate amelioration, land sustainability, biodiversity preservation, etc. All trees are multipurpose; some, however, are more multipurpose than others. Tree species can be multipurpose in two ways.

1. A single tree can provide more than one function. For example, Gliricidia sepium is grown as living fences that provide fuel, fodder and green manure for agricultural crops - all at the same time.

2. Trees of the same species, when managed differently, can provide different functions. For example, Leucaena leucocephala is managed so that some trees will mainly yield wood while others mainly produce leaf fodder.

All animals with cataract are not suitable candidates for surgery. Pre-surgical assessment of a candidate is essential to make a safe judgement for surgical procedure to perform lensectomy. Failure in canine cataract surgery can be associated with poor case selection. A thorough ocular and physical examination should be performed to rule out other ocular diseases prior to cataract surgery. The cataractous lenses in both eyes must be mature to cause functional loss of vision. (24).

The following prerequisites should be fulfilled before cataract extraction is recommended (6):

1. The affected eye should have a significant visual deficit.
2. For the patient to regain vision, its retina must be healthy and functional. if the fundus cannot be examined thoroughly (because of the cataract), retinal function should be evaluated with electroretinography (ERG) to ensure that retinal degeneration is not present as the patient history, signalment, and the speed of pupil contraction

Phytochemicals from various parts of a plant or tree such as the leaves, the flowers, the seeds, the barks, the roots and the shrubs can be isolated. Once one comes in from collecting plants in the field, it is good idea to freeze them immediately in a freezer at – 20°C or a commercial freezer held at – 80°C (Kaufman et al., 1999). According to Harborne (1984, 1998), fresh plant tissues should be used for phytochemical analysis and the material should be plunged into boiling alcohol within minutes of its collection. Alternatively, plants may be dried before extraction.

Phytochemicals from various parts of a plant or tree such as the leaves, the flowers, the seeds, the barks, the roots and the shrubs can be isolated. Once one comes in from collecting plants in the field, it is good idea to freeze them immediately in a freezer at – 20°C or a commercial freezer held at – 80°C (Kaufman et al., 1999). According to Harborne (1984, 1998), fresh plant tissues should be used for phytochemical analysis and the material should be plunged into boiling alcohol within minutes of its collection. Alternatively, plants may be dried before extraction. It is essential that the drying operation is carried out under controlled conditions to avoid too many chemical changes occurring. Once thoroughly dried, plants can be stored before analysis for long periods of time. It is possible to isolate some of the compounds from herbarium samples. One example of the use of the herbarium material is the essential oil analysis that was carried out on type specimens of Mentha leaf, the material being obtained from the original collection of Linneaus made before 1800 (Harborne, 1998). An obvious point to follow by the research worker is freeing of the plant tissue under study from contamination with other plants. While collecting roots, care must be taken that we are collecting roots from one plant. It is essential to use plants which are free from disease, i.e. which are not affected by viral, bacterial or fungal infection. In phytochemical analysis, at some stage in the investigation, a botanist of an acknowledged authority must authenticate the botanical identity of the plants studied and a voucher specimen of the plant may be deposited in a reputed Herbarium for future reference. It is advisable to keep a logbook of the plants that have been collected and used for phytochemical analysis. A backup inventory on the computer is also a good idea.

Pump is a mechanical device to increase the pressure energy of fluid. Aquacultural enterprises often find it necessary to move fluid against an energy gradient. Most commo n may be filling or emptying of tanks. For performing an assigned job, the best selection of pumps should be such that it should work at its peak efficiency. Unfortunately, there is only one head and discharge condition for each pump where the peak efficiency is obtained and therefore, it is rarely possible to achieve the highest efficiency for a pumping condition. Manufacturers cannot design and build so many varieties of pumps to meet all operating conditions. They have therefore, settled upon some standard designs which are generally required for most of the head and discharge conditions.

Homoeopathic treatment is based on an overall understanding of the symptoms in the body and mind created by a sickness. Dr. Samuel Hahnemann, the founder of the homoeopathic science of healing, after years of experiment and trial, came to finding that symptom - similarity is the curative method of medically curable diseases. In paragraph 25 of the 'Organon of Medicine⁷, he formulated the principle of 'like cures like' in these words: " Now, however, in all careful trials, pure experience, the sole and infallible oracle of the healing art, teaches us that actually that medicine which, in its action on the healthy human body, has demonstrated its power of producing the greatest number of symptoms similar to those observable in the case of disease under treatment, does also, rapidly, radically and permanently remove the totality of the symptoms of this morbid state, that is to say, the whole disease present, and change it into health; and that all medicines cure, without exception, those diseases whose symptoms most really resemble their own, and leave none of them uncured."

The aforesaid indicates the importance of symptoms in the diagnosis and treatment in homoeopathy. If a drug creates a symptom during the course of proving, then it can be cured by a potencised dose of the drug; whatever may be the name of the disease. For instance, in proving GLONOINE produces a bursting, throbbing sensation in the head in a healthy person. Conversely any surging of the blood to the head requires GLONOINE. This can happen in a sun - stroke, in high blood pressure, in cerebro - spinal meningitis. KALI BICROMICUM produces in proving, a tough, stringy discharge of mucus. In homoeopathy, KALI BICROMICUM cures a similar discharge whether from the nose inwards from mouth, from fauces, from pharynx, from larynx, trachea, bronchi, vagina, and uterus or from any mucus membrane. CACTUSGRANDIFLORUS produces in pure form and gross doses, constriction of the heat and a constriction, anywhere in the body, which is like an iron band being tightened. The same sensation of constriction leads us to the use of CACTUS in a homoeopathic dose and it need not be confined to the heart. There can be constriction of the scalp, in the oesophagus, in the chest, in the abdomen, bladder, uterus, vagina or rectum.

The selection of the site has great importance for the establishment of a fruit orchard successfully. Establishment of orchard is a long term activity with huge investment. Hence, any mistake committed during site selection, it is difficult to rectify it later. Successful orchard is not only related with yield but also its economic production and efficient disposal of produce. For economic orchard establishment; some of the points which need to be considered, while selection of site. These are as follows.

1. Climate and soil: These are two important natural factors, which decide the success or failure of orchards. Before selection of site, climate and soil requirement for selected fruit crops needs to be studied thoroughly and accordingly site must be selected. On the other hand if a site has already been selected; then fruit crop selection needs to be done as per the existing climate and soil of that selected site.
2. Topography: Slope of site more than 15% makes the land almost unsuitable for cultivation. Land with 4% slope may be kept clean without much loss. Uneven land involves heavy expenditure in leveling. Southern slopes are generally warmer and affect the plant growth in a manner different from the northern slopes. It is due to the difference in quantum of receiving sunlight. Hence, the site with southern slopes may be selected for sun loving plants.

Farmers have been growing trees for different purposes for thousands of years. Tree species that are grown to provide more than one significant function are called multipurpose trees. These functions may be productive such as producing fuelwood, timber, fibre, fodder, food, medicine, etc. and/ or protective such as soil conservation, shade, shelterbelt, microclimate amelioration, land sustainability, biodiversity preservation, etc. All trees are multipurpose; some, however, are more multipurpose than others. Tree species can be multipurpose in two ways.

1. A single tree can provide more than one function. For example, Gliricidia sepium is grown as living fences that provide fuel, fodder and green manure for agricultural crops - all at the same time.
2. Trees of the same species, when managed differently, can provide different functions. For example, Leucaena leucocephala is managed so that some trees will mainly yield wood while others mainly produce leaf fodder.

Farmers can grow multipurpose trees (MPT) in various combinations with other crops, as in agroforestry, in block plantations of trees or in naturally regenerating tree farms. In certain cases, multipurpose trees are grown and managed for only one purpose. For example, Gliricida sepium is grown only to provide shade in coffee plantations. The same species may be planted in some other places and is managed differently for a very different use.

Farmers have been growing trees for different purposes for thousands of years. Tree species that are grown to provide more than one significant function are called multipurpose trees. These functions may be productive such as producing fuelwood, timber, fibre, fodder, food, medicine, etc. and/or protective such as soil conservation, shade, shelterbelt, microclimate amelioration, land sustainability, biodiversity preservation, etc. All trees are multipurpose; some, however, are more multipurpose than others. Tree species can be multipurpose in two ways. 1. A single tree can provide more than one function. For example, Gliricidia sepium is grown as living fences that provide fuel, fodder and green manure for agricultural crops - all at the same time. 2. Trees of the same species, when managed differently, can provide different functions. For example, Leucaena leucocephala is managed so that some trees will mainly yield wood while others mainly produce leaf fodder.

Farmers have been growing trees for different purposes for thousands of years. Tree species that are grown to provide more than one significant function are called multipurpose trees. These functions may be productive such as producing fuelwood, timber, fibre, fodder, food, medicine, etc. and/or protective such as soil conservation, shade, shelterbelt, microclimate amelioration, land sustainability, biodiversity preservation, etc. All trees are multipurpose; some, however, are more multipurpose than others. Tree species can be multipurpose in two ways.

Background

Sheep and goats are the poor man’s cow because of the lower capital investment, and production costs. Also supplies milk quantities that are suitable for immediate household consumption thereby reducing problems of milk storage and marketing. Small ruminants, goats and sheep, mainly localized in the arid, semi-arid and mountainous areas of the country, have multi-faceted utility in terms of wool, meat, milk, skins, (mo)hair/pelts, manure and have also acquired socio-cultural niches in many communities (Kosgey and Okeyo, 2007). Goat and sheep milk has many advantages over other livestock species’ milk being easy in digestion, non-allergic, naturally homogenized, improves immunity as it has antifungal and anti-bacterial properties. However, rearing small ruminants for meat is more popular among farmers as price of chevon and mutton are very high, continuously increasing over the years and sale of male for meat is easy, steady and accessible at farmer’s place or local places unlike milk, skin and fibre. Thus, small ruminants (SR) occupy a promising agrarian and economic niche in low to medium input production systems, not suitable for growing crops and dairy farming (Devendra and Chantalakhana, 2002), mostly driven by small and marginal farmers and landless laborers. Their meat and milk production represents 4.8% and 3.4% of the total meat and milk produced, respectively, in the world.

3.1 Selection of Breeding Bulls

A sire is called half the herd and the breeding bulls to be used for semen production should be carefully selected. Selection of superior sire for breeding purpose is very important for the success any livestock breeding programme. Therefore, breeding sire must be carefully selected and maintained in scientific way so that its breeding life is prolonged and maximum number of frozen semen doses can be produced from it. 
The selection criteria for future bulls should be meticulously designed keeping into account all the factors/parameters which affects the breeding programme. The selection of breeding bulls is based on three broad parameters-

3.1.1 Pedigree Examination
3.1.2 Gross Physical Examination
3.1.3 Laboratory Examination

Natural Selection
In nature, the main force responsible for selection is of interest because of its apparent effectiveness and because of principles involved. Some of the most interesting cases of natural selection are those involving man himself. All races of man that now exist belong to the same species, because the races are interfile or have been in all instances where mating have been made between them. All races of man now in existence had a common origin and at one time probably all man had the some kind of skim pigmentation – which kind we have no sure way of knowing. As the number of generations of man increased, mutations occurred in the genes affecting pigmentation of the skin causing genetic variations in this trait over a range from light to dark or black.
Natural selection is a very complicated process and many factors determine the proportion of individuals that will reproduce. Among these factors are differences in mortality of the individuals in the population especially early in life, differences in the duration of the period of sexual activity and in the degree of sexual activity itself and the differences in the degree of fertility of individuals in the population. They are also examples of adaptive evolution.

Introduction

Aquaculture is one of the rapidly growing industries worldwide with more than 300 different species being cultured. However, majority of aquaculture species are still wild and undomesticated, and the adaption of relevant technologies in the aquaculture sector has been slow. Given that genetically modified stock only accounts for less than 10% of the current global aquaculture production, the aquaculture sector has significant potential to increase production efficiency through selective breeding programmes. Selective breeding is acknowledged as a crucial element in the generation of resource-efficient, sustainable, and profitable aquaculture operations (FAO, 1995; World bank, 2006).

ABSTRACT

Apot culture experiment was conducted on tomato with cadmium and lead to identify the selective retention sites of the metals. For this a completely randomized design with five treatments and four replications were laid out at the College of Horticulture, Vellanikkara. The different levels of treatment ranged from 0.5 to 2.0 mg kg -1 soil. Cadmium and lead were directly supplied as a water-soluble source through cadmium chloride and lead nitrate respectively. In tomato the growth and fruiting was permitted only at lower levels of cadmium application. At 1.5 mg kg-1 soil, fruiting failed. While at 2.0 mg kg-1 soil, the very establishment of plant was totally affected. At higher levels of application, cadmium preferred to get accumulated in roots while on the contrary at lower levels, cadmium uptake increased in shoots than in roots with the least content of the metal in fruits. However, in the case of lead, all levels of application in soil permitted growth and fruiting. With increase in rate of lead application, significant selective retention was observed in roots (1.48-6.69 ppm), shoot (0.29-1.62 ppm) and fruits (0.39-1.45 ppm). On comparison of retention sites of lead in tomato, it could be seen that fruits maintained the maximum lead uptake (637.2-2933.0 mg pot-1). Hence, the consumption of such tomato fruits contaminated with heavy metals may result in kidney damage, lack of memory, dissolution of phosphorus in the bones etc.

Origin and Concept of SHGS
    
The origin of SHGs is from the brainchild of Grameen Bank of Bangladesh, which was founded by Mohammed Yunus.  SHGs were started and formed in 1975.  In India NABARD is initiated in 1986-87.  But the real effort was taken after 1991-92 from the linkage of SHGs with the banks.  A SHG is a small economically homogeneous affinity group of the rural poor voluntarily coming together to save small amount regularly, which are deposited in a common fund to meet members emergency needs and to provide collateral free loans decided by the group (Jha 2000).  They have been recognized as useful tool to help the poor and as an alternative mechanism to meet the urgent credit needs of poor through thrift (Rao 2002) SHG is a media for the development of saving habit among the women (Rajamohan 2003).  SHGs enhance the equality of status of women as participants, decision-makers and beneficiaries in the democratic, economic, social and cultural spheres of life.  (Jain 2003).

Introduction
India with exceeding population of 1027.01 million with 741 million living in rural areas is on the path of development. The lack of access to and control over resources is said to be cause of poverty (Satapathy and  Mishra, 2011).
Women form half of our society. They have significant role in overall development. Rural development concept in our country attaches more importance to women empowerment. To combat poverty ‘self help promotion’ is of recent paradigm that has attracted attention to sections of the society.

Introduction

Since six decades after independence, the existence of people in a state of social, economic, political and knowledge disempowerment is considered as major threat to overall development. There is an essential demand for the integrated development, which should cover up development in all aspects, specifically in status, equality, security, complete physical, mental and social well-being of the target group. One sided emphasis on economic achievements by policy makers has set in motion so for But the social cleavage in rural areas has deepened. The power to the people signifies a new movement, which has been born out of the realization that society’s traditional arrangements for voicing their problems are very meager. The economic growth does not mean that only creation of wealth, but also creation of people’s capacity to create wealth and this resides in their health, education, knowledge and skills. It has been proven fact that, the economic development in any country should be preceded by social development which is interdependent. To combat the poverty at present juncture, efforts should be through the group approach only. So the new paradigm like Self - Help Groups (SHGs) can attain sustainability because of the clear cut understanding among them. Almost failure of co-operatives to mitigate unemployment problems and combating rural poverty, it is essential to think over self help group approach to empowering the rural poor.

Self incompatibility in plants is a mechanism preventing the seed set by self pollination, and is probably way in which out crossing is enforced. Other factors may cause selfed seed may not to set seed due to embryo abortion, but SI is prezygotic and prevents embryo formation. SI is, therefore prevention of fusion of fertile male and female gametes after fertilization. Koelreuter first time in 18^th century reported S.I in Verbascum phoeniceum plants. In self-incompatible pollen grains fail to germinate on the stigma of the flower that produced them. Self incompatibility has been reported in more than 300 plant species belonging to 70 family of angiosperm. It is important out breeding device (cross pollination) for normal fruit set. It is maintained high degree of heterozygosity and can take place at any stage between pollination and fertilization.

Self-Incompatibility

This is lack of self-fruitfulness and is a condition where the pollen from a flower is not receptive on the stigma of the same flower resulting into no seed setting. This happens despite the fact that pollen and ovule development both are normal and viable. This is caused by genetically controlled physiological hindrance to self-fertilization. This occurs widely among diverse families of flowering plants including the Leguminosae, Onagraceae, Rosaceae, Scrophulariaceae, Solanaceae, Compositae, Cruciferae, Papaveraceae and the Gramineae (now called as Poaceae). The incompatibility reaction is genetically governed by a single locus designated as S with multiple alleles whose number can go more than 100 in some species such as Trifolium pretense. East has estimated that this occurs in more than 3000 plant species distributed over 20 families. Lewis classified incompatibility systems into two main groups, namely, heteromorphic and homomorphic and homomorphic system has further been divided into gametophytic and sporophytic types as illustrated below:

To start with let the self-incompatibility be defined.

• Self-incompatibility is the mechanism by which plant can prevent selffertilization.
• Self-incompatibility is defined as inability of a plant producing functional gamete to achieve self-fertilization.
• Self-incompatibility is a genetically based mechanism which controls mating within angiosperm species by imposing a ‘barrier’ between pollination and fertilization.
• The term incompatibility is used to describe the failure of pollen tube to penetrate the full length of the style and to effect fertilization.

Semen is admixture of secretions of testes containing spermatozoa and accessory sex glands. Spermatozoa are formed in the seminiferous tubules of the testes. The tubules contain a complex series of developing germ cells that ultimately form the male gametes. The spermatozoa are unique type of cells containing nucleus (head portion) and a tail. The acrosome is a double walled structure situated between the plasma membrane and the anterior portion of the sperm head and neck connects the sperm head with its tail.

Semen collection is the most important component of any frozen semen production programme as a high quality end product is not possible unless the raw material is of excellent quality. Therefore, all care should be taken to collect semen aseptically with the aim to harvest the best quality neat semen for processing. The person collecting semen should understand bull’s behaviour and should be friendly with him. Professional bull management results in increasing sperm output and enhancing productive life of the bulls. One must know potentials and limitations of the reproductive capacity of bulls. A highly professional and dedicated team of bull handlers and semen collectors is required for this purpose. The persons involved in bull management should be familiar with bull’s sexual behavior and male reproductive physiology. Preferably a veterinarian should collect semen.

Semen collection in bulls and buffalo bulls

Semen collection from domestic animals is an art and skilled job to get maximum quantity and quality of an ejaculate. Ejaculation of semen in a male is a complex process and consists of several events sexual arousal, courtship, erection, penile protrusion, mounting, intromission, ejaculation, orgasm like reaction and dismounting. Ejaculation is the result of neuro-muscular stimulation that starts in the vas differentia and accessory sex glands. The semen ejaculation is finally brought about by the rhythmical contractions of penile musculature and urethra. The muscular contractions proceed progressively in waves, forcing the semen out of the external urethral orifice. To get good quality semen, the bulls must undergo all the related events of ejaculation. The semen collectors should have knowledge of inhibitory and stimulatory factors for the act of ejaculation in male domestic animals. The stimulatory factors are:

• Semen cryopreservation – It is the process of preserving the semen in a suitable medium at an ultra-low temperature which reduces spermatozoa metabolism with the least production of metabolic waste products of sperm cells to prolong their life span. • Every fall of 100 C temperature decreases the metabolic rate of spermatozoa to half. Principle of various components involved in cryopreservation 1. Low temperature • Reduce metabolism (negligible) and least metabolic waste product • Decrease solute solubility leads to increased viscosity and physical resistance • Reduce motility • Prolong life span 2. Protection from cold shock and cryoinjury • When sperm cells are subjected to a reduction in temperature during the freezing process, there are: • Sperm membrane damages and lead to leakage of intracellular components like enzymes, ATP, K+ , cholesterol, lipoproteins etc. • Irreversible abnormality in motility pattern (bending of sperm tail)

Semen dilution/ extension is done to meet the following objectives

1.    To preserve the fertilizing potential of semen for a long period of time

2.    To increase the number of services per ejaculate. Ideally approximately 500 cows/ buffaloes can be inseminated from diluted/ extended semen of  a single ejaculate.

3.    Extenders provide the spermatozoa with a medium in which they are able to remain viable and fertile for a prolonged time period.

In order to be an ideal extender, it should be able to provide conducive environment to prolong sperm survival and modify the sperm structure to prepare them for freezing through the following properties:

1.    It should be isotonic with blood and should maintain this during preservation.

The idea behind semen dilution is to extend its volume without affecting its fertility so that many females can be bred from an ejaculate. The basic components of semen extender are Tris buffer, fructose, glycerol, egg yolk and antibiotics.

Semen evaluation alone should not be interpreted as the sole indicator of the fertility of bulls but it will provide significant information of the sexual apparatus. After receipt of the semen sample in the laboratory, it is kept in a hot water bath at 350C until the evaluation is complete. One has to prevent cold shock to the living sperm cells during the evaluation process. All the glassware and other items coming directly or indirectly in contact with the sperm cells should be sterilized properly and kept ready in a thermostatically controlled cabinet at body temperature. Sudden changes in exposure of semen to cold or hot temperature results in higher dead spermatozoa or sperm agglutination. Semen should not be exposed to sunlight, wind, chemicals, smoke, vibration and water. A single laboratory test is not sufficient to assess the semen quality and semen should be examined within a shortest possible time after ejaculation as mentioned below (Table 9.1).

Microscopic examination 

A phase contract microscope with biotherm (37o C) is necessary for correct evaluation of semen because the refractive index of spermatozoa differs slightly from that of the surrounding medium. The ordinary bright field microscope will not provide sufficient contrast between the spermatozoa and the medium. Under phase contrast microscope, the object will appear dark on a bright background. This is achieved by reducing the light passing through the object by half a wavelength compared to the light passing through the medium. The eyepiece has a magnifying capacity of 10X while the objectives have 10, 40 and 100X. This will provide the microscope the magnifications of 100, 400 and 1000. The lenses and eyepiece should be kept clean by wiping with tissue paper and distilled water. Xylol can also be used to remove greasy material. The microscope has to be kept in one place and covered with Perspex cover when not in use to avoid dust accumulation. Personnel familiar with the operation of a particular microscope alone should be allowed to handle the microscope, since lot of differences exist between different makes of microscopes. 

Good quality semen is more acidic than semen with lower sperm concentration. In contrast, bacterial contaminated semen and semen with more dead spermatozoa evolve ammonia that will increase pH of semen. In orchitis, seminal vesiculitis and epididymitis the pH of semen will be alkaline due to presence of pus. In azoospermic or necrozoospermic semen, the pH may be neutral or alkaline. pH variation may be due to change in season/climate and frequency of successive ejaculates. Depending on the concentration and activity of spermatozoa, the pH of semen varies. The narrow range pH (BDH) paper are more convenient in routine work. The first change in color is matched with color on the cover of booklet. Use of BDH capillary set is time consuming whereas digital pH meters are also being used. The normal pH range is depicted in Table 11.1.

Semen is needed to be extended with a suitable medium and cryopreserved without affecting its survivability and fertility for the purpose of inseminating female artificially. Qualities of Ideal Extenders • Semen extender is a nutrient media which provide energy to spermatozoa, protection from osmotic shock, thermal shock and various metabolic wastes for prolonging the life span of sperm cell with maintaining the acceptable fertilizing capacity. A semen extender should have qualities to protect spermatozoa during dilution and cryopreservation. These qualities may be : 1. Preserving sperm cell integrity (membrane, cellular, mitochondrial and acrosomal integrity etc) 2. Maintenance of osmotic pressure (isotonic; 280-300 mOsm/l) similar to seminal plasma 3. Providing nutritive elements as energy source for sperm metabolism (aerobic & anaerobic metabolism)