eChapters

Regular deworming of cattle including young stock is essential for economic rearing as sever parasitic infection leads to reduced feed intake, decreased reproductive performance, lower milk production, decreased growth rate and increased incidence of diseases. So, deworming as per scientific schedule and dose rate is a must for animals to keep away these profit eating parasites.

A cow is called repeat breeder when it has failed to conceive even after three or more number of services, has normal estrus cycle length, no abnormal vaginal discharge, no palpable abnormality in the reproductive tract, has calved at least once before and is less than ten years of age. Repeat breeding is one of the most important infertility problem faced by field veterinarians.

Causes

1) Fertilization failure

2) Early embryonic death

Main Points that Need to be Known by a Farmer About Repeat Breeding Cow

• Signs of estrus like vaginal discharge and its color, bellowing, mounting etc

• Time of estrus as observed by owner (morning, evening etc)

• Vaginal discharge whether clear or mucopurulent/purulent

• Duration of estrus

• Inter-estrous interval

• Number of inseminations

In subclinical endometritis (SCE), there is inflammation of the internal lining of uterus (endometrium). It is one of the major causes of repeat breeding in cattle and causes significant reduction of reproductive performance. Cervico- vaginal mucus in subclinical endometritis is clear in contrast to endometritis. It is also called cytological endometritis and is associated with increased proportion (percentage) of polymorphonuclear cells (PMN) in endometrial cytology samples. SCE affected cows have delayed first service and subsequent pregnancy causing significant economic losses due to reduction in reproductive performance, feed intake increase per lactation, milk yield reduction and increase in culling rate.

The following objectives are accomplished by semen dilution/ extension

• Preservation of semen potential over a long period of time.
• Increase in the number of services per ejaculate. Ideally approximately 40 does can be inseminated from diluted/ extended semen of a single ejaculate.
• Extenders provide the spermatozoa with a medium in which they are able to remain viable and fertile for a prolonged time period. An ideal extender should be able to provide a conducive environment to facilitate sperm survival and modify the sperm structure to prepare them for freezing through the following properties:
• It should be isotonic with blood and should maintain this during preservation.
• It should have capacity of maintenance of pH (6.6-6.8) with high buffering capacity in that range.

Goats remain an important and instant source of income as well as livelihood for the majority (70-90 %) of small and marginal farmers in India. Goats are the animals with multiple utility like milk, meat, hide, fibre and manure. They are more tolerant to harsh environment (better resistance to heat stress and drought, better utilization and digestibility of pastures) and give more production per unit investment. Goats are spontaneously ovulating, poly-estrous animals and show seasonal pattern in reproductive activity related to the annual variations of photoperiod. Onset and length of their breeding period throughout the year is dependent on different environmental and physiological factors viz. latitude and climate, feed and fodder availability, breed and breeding system. This in turn affects round the year availability of meat and milk to full fill the market demands. When kids are born out of season, adequate supply of pastures along with good management practices must be ensured in order to minimize kid’s mortality and promote their optimum growth.

All living organisms need to reproduce in order to maintain their species and improve the economics of animal husbandry. Since the beginning of time, different methods of successful reproduction have been created, including artificial insemination and in vitro fertilization. To shield sperm from damaging elements like freezing, osmotic shock, oxidative stress, and cell damage by ice crystals, semen extenders were developed. Semen extenders maintain sperm’s characteristics, such as its morphology, motility, and viability as well as its membrane, acrosomal, and DNA integrity. To improve semen quality for fertilization, semen extenders must offer a suitable pH, adenosine triphosphate, anti-cooling and anti-freeze shock, and antioxidant activity. As a result, this compilation of research offers exact information on various semen extenders, preservation mechanisms, and crucial semen extender additions in goats. By incorporating various types of additives in semen extenders for cryopreservation, significant improvement is reported in post thaw sperm quality in terms of increased % motility, viability, PMAI, MMP and reduced DNA fragmentation, capacitation like changes reflected by less CTC pattern B and AR, Tyrosine Phosphorylated pattern A, E and AE.

The male genital system consists of:

1. The pair gonads, the testes
2. Epididymis
3. Vas deference or ductus deference
4. Accessory glands (Seminal vesicles, prostate glands, & bulbo-urethral glands)

The goats play a vital role in the economy of the poor and marginal farmers of rural India. Notwithstanding the fact that the goat population has shown a steady growth over the year’s very little effort has been taken for genetic improvement at farm level. As per 20th Livestock Census, 27.74% of the livestock population is Goats. Out of 148.88 million Indigenous Goats (Including Non-descript), 27.4% are pure breed, 9.1% are graded breeds and the remaining 63.5% are non-descript breeds. So, to increase the productivity per goat, we need to improve the breed quality scientifically. Artificial insemination (AI) using frozen semen is practiced to produce superior progeny and to accelerate the up gradation of stock. The conception rate with AI is lower but it has great potential to multiply superior quality of goat with faster rate. This technique also spread elite genetic material throughout a population with increased rate of genetic improvement. This technique is also important for the breed conservation process and has paved the way for other reproductive biotechnologies. The sufficient elite germplasm of male buck is not available throughout the country to cover breeding programmed by natural mating. AI is the best solution to improve the quality and productivity per goat.

The selection of breeding bucks in relation to maximizing the reproductive efficiency depends upon males. AI permits intense selection of sires with exceptional merits and provides opportunity to exploit the value of superior sires. Young males can be trained for exhibiting sexual behaviors and semen collection through the uses of male, anoestrus doe or oestrus doe as dummy. Successful AI depends on precise management of semen collection, its frequency and use. The semen collection implies mounting a teaser doe or a dummy. Artificial vagina (AV) and electro-ejaculator (EE) are the two methods for semen collection in bucks. AV 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. Moreover, this method of collection is painful for the animals. Semen evaluation should be rapid and effective so that collected semen samples can be processed for initial quality which ultimately affects the fertility. There are several tests for the assessment of semen quality but no single test is reliable to give definite prediction of the fertility.

The successful AI program depends on the health of the semen donors followed by hygiene in semen collection, processing, storage and AI methods as well as reproductive health of the females. However, the microbial contamination may not be able to avoid completely but it can be reduced to the minimum threshold level by adopting hygienic procedures.

The hygienic condition of the neat / frozen semen samples can be assessed periodically by enumerating the bacterial load apart from the periodical screening of bucks for the presence of various causative agents in animals and its transfer to the females via semen samples.

Though both viable and total (viable and nonviable) bacterial counts can be done, the viable techniques are more commonly used in diagnostic and food hygiene procedures. The viable bacteria are capable of multiplication with the production of visible colonies on or in agar media. In viable techniques, the assumption is made that one well-spaced bacterial cell gives rise to one colony. The bacterial colonies, rather than bacterial cells, are counted in these techniques. Among the viable counting techniques like Spread plate, Pour plate, Miles, Misra, Filtration are available and each has its own inherent errors, the pour plate counting method is explained as follows:

Ian Donald in the year 1956 used the one-dimensional A-mode (amplitude mode) to measure the parietal diameter of the fetal head and thus introduced the ultrasound in diagnostic and medicine. Ultrasonography does not use radiation or powerful magnetic field as source of energy and the equipment cost is usually affordable. This modality involves the use of sound waves in viewing the longitudinal, sagittal and transverse planes for both testes . Sound is measured in cycles per second or hertz (Hz); the audible range of sound is from 20-20,000 Hz. Diagnostic ultrasound is usually in the range of 1–20 megahertz (MHz).

The speed of sound depends on the tissues through which it propagates because density and compressibility change the speed, the sound wave travels. On an average the assumed speed of sound in soft tissue is 1540 m/s.

India has a mega animal bio-diversity, which is manifested in the form of availability of a large number of species, and a variety of breeds even within species. India is bestowed with rich and varied domestic animal biodiversity having a total of 32 breeds of cattle and 10 buffalo breeds. The diversity of livestock is not only accidental, nor purely natural; it is more the outcome of thousands of years of continuous selection. The trends in livestock population over the last three decades have shown that, there is significant increase in the population of buffaloes i.e. from 60.5 crore in 1973 to 96.9 crore in 2003, while cattle population has increased from 180.1 crore to 226.1 crore in the same period. The share of buffaloes, in the bovine population increased from 22 to 32 per cent while that of cattle has shown declining trend. Within the cattle, there has been marked shift from work animals towards milch animals which has resulted in loss of important draught breeds of cattle. Further indiscriminate crossbreeding has resulted in significant decline in number of important milch breeds like Sahiwal.

Biological and chemical reactions in living cells are dramatically reduced at low temperature, a phenomenon that can lead to the possible long-term preservation of cells and tissues. However, freezing is fatal to most living organisms, since both intra and extracellular ice crystals are formed and results in changes to the chemical setting of cells that lead to cellular mechanical constraints and injury. The major hurdle for cells to overcome at low temperatures is the water-to-ice phase transition. Cell injury at fast cooling rates is attributed to intracellular ice formation, whereas slow cooling causes osmotic changes due to the effects of exposure to highly concentrated intra and extracellular solutions or to mechanical interactions between cells and the extracellular ice. Cryopreservation is a process that maintains biological samples in a state of suspended animation at cryogenic temperature for any considerable period and is used to preserve the fine structure of cells (Jang et al., 2017).

The choice of hormones and drugs acting on reproductive system are important as therapeutic agents during reproductive disorders like anoestrus, metritis, pyometra, repeat breeder, retention of fetal membranes, delayed puberty, ovarian disorders etc.  The administration of specific chemotherapeutic agent is of paramount importance in treating reproductive disorders in dairy animals.  The dosage, route, frequency and indications of chemotherapeutic agents acting on reproductive system are mentioned in tabular form as below.

Artificial Insemination is a very important tool that caters to propagation of high-quality germplasm and breed improvement. It is also economical as it aids in breeding without the necessary to maintain the adult bucks cutting the input cost. However, the bucks maintained for production of semen and AI should be free of any diseases and in specifically venereal diseases. Venereal diseases are not so uncommon in livestock, and they cause a variety of symptoms including orchitis, abortions, still birth, vulvovaginitis etc., leading to infertility in breeding animals. Venereal diseases are infectious in nature and they are transmitted mainly through semen, feed-water, AI gun, artificial vagina, fomites etc. Due to venereal diseases, infertility, orchitis, epididymitis, vasculitis etc. occurs in bucks and leads to abortions and still birth in does (Ahmed et al, 2010; Beena et al, 2017), because they are directly linked with the economic output (Sharma et al, 2008; Azawi et al, 2010) and overall health of the animal affecting the productivity significantly (Menzies, 2011). To keep abortions and other venereal diseases at bay, it is important to raise disease free breeding bucks that deliver clean-semen for natural service or AI operation. Abortion rate between 2 to 5% indicates its endemic nature and abortion level exceeding 5% requires aggressive investigation (Menzies, 2011). Infectious agents that include viruses, bacteria, fungi, parasites etc.; as well as noninfectious cause can lead to infertility in goats (Moeller, 2001; Szeredi et al, 2006; Smith and Sherman, 2009). Many infectious causes are known to mankind that leads to trans-venereal diseases in goats including Brucella melitensis, Chlamydiosis, Campylobacter spp., Listeria monocytogenes, Toxoplasmosis, Coxiella burnetii etc. There are numerous viruses such as

Non-specific uterine infections reduce the reproductive efficiency of livestock.  They are called nonspecific because the initial colonizing bacterium is not known and the specific bacteria causing the signs of infection are not known.  Even though numerous bacteria, in a variety of combinations, have been isolated from infected uteri, Corynebacterium pyogenes and Escherichia coli are usually associated with uterine infections in cattle and sheep.  Empirical therapeutic approach, prescriptions without scientific validation (extra-label use) or inadequate clinical judgment itself to ascertain the nature of uterine infection, obviously due to lack of diagnostic tools are the prime reasons for therapeutic failure for the unsuccessful treatment of uterine infection by large animal practitioners.

Estrous cycle

After puberty the female enters a period of reproductive cyclicity, which continues throughout most of her productive life.  Estrous cycle is the rhythmic sexual behavioral pattern exhibited by the female, which begins at one estrus (heat) and ends at subsequent estrus.   It is the period between two estruses of the regular cycle.  The reproductive activity of the female is maintained by the co- ordinated functioning of different organs of reproduction (Table: 1.1). Estrous cycle provides repeated opportunities for the females to become pregnant. When conception does occur, the female enters a period of anestrous during pregnancy, which ends after parturition (giving birth) and uterine involution (repair and returning to normal size).

Faulty estrus detection is the most important problem in reproductive management.  There are two requirements for good estrus detection: a skilled observer must spend sufficient time to make observations and cows must show overt signs of estrus during the period of observation.  There are various ways to detect the estrus signs in cows and buffaloes as detailed below.

1.    Palpation of reproductive organs:  Routine rectal examination of all cows between 30-40 days after calving and individual cow that has not been inseminated within two months after calving should be encouraged.   This is to confirm that the reproductive tract is normal and to predict when the next estrus will occur or to identify cows for prostaglandin treatment when estrous cycles are occurring, but estrus has not been detected. 

2.     Teaser bulls:  Teaser bulls are useful in identifying estrus in large number of animals especially buffalo cows.   Teaser bulls can be prepared by vasectomy or by applying apron to a bull. 

3.     Heat detector animals:  Sexually active animals like bulls, cystic cows, hormone treated steer, cows and heifers can be used to identify estrus cows.    They may be fitted with halters containing ink- filled reservoirs and ball paint pen type devices (chin ball markers) that will mark animals that mounted or they can be used without these devices to increase the sexually activity and make visual detection programs more effective.

Synchronization of estrus is making a group of cows to come into estrus at the same time.  Effective estrus detection requires much time, labour, skill and expense and it is a major limiting factor in artificial insemination programme in cattle.  It was the principal stimulus that led to research in the development of progestational and prostaglandin compounds. 

Advantages

1.     Improve the efficiency of heat detection

2.     Management tool, better planning of breeding activities and wider use of artificial insemination 

3.     Solve problem of unobserved estrus

4.     Maintain short calving interval

5.     Overall improvement in herd productivity and reproductive efficiency

6.     Controlled lactation

7.     Management of replacement heifers

8.     Useful in embryo transfer programmes

9.     Reduce labour

10.     Possibly reduce involuntary culling for reproductive reasons