Factors Affecting Conception Rate in ArtificialInsemination of Cattle and Buffaloes

Dr. Kedar Karki (M. V.St. (PREVENTIVE VET. MEDICINE).Background.Artificial Insemination (Al) with ctrozen semen contributes sign ficantly to the cross breeding and upgrading of cattle and buffaloes. For more than 50 years, Al has had the greatest contribution in increasing milk and meat production. However, its coverage in India is still assumed to be ranging between 10-15% of the cattle and buffalo population. The obvious reason for this poor coverage is low conception rate (CR) with Al, but why Al. There is a consensus among researchers that natural service gives better CR than Al, but why it should be so, is uncertain because the success of Al depends upon a lot many factors such as fertility of the semen, time of insemination, skill of inseminator besides the management of females (Hafez, 1993). The purpose of this paper is to focus those factors that affect the CR in Al of cattle and buffaloes along with remedial measures. Male factorsBulls should be selected based on pedigree and physical conformation tests. It should be tree from diseases like Brucellosis vibriosis, trichomaniasis, tuberculosis etc. Once the bull passes through these tests, it should be subjected to routine semen analysis, Now-a- days, improved in vitro fertility tests like cervical mucus sperm swelling test, zona free hamster oocyte test etc., are available for predicting the fertility of bulls. However, the fertility of bulls should be confirmed by it vivo fertility trials. Spermatozoa have better freezability. After that, they can be used for routine semen collection, preservation and insemination.Female factors 1. Congenital defects There are due to arrested development of different segments of reproductive tract. This may vary from mild hypoplasia to complete lack of a particular part of reproductive tract. Even though most of them can be ruled out by rectal examination, some defects like arrested oviductal development etc., should be conformed to special tests. Tubal blockage can be diagnosed by injecting 10 ml of 0.1% phenol red solution intra uterine in one horn preferably at the tip of the horn and urine is collected after half an hour to with in three hours by catheterization. If the colour of urine is pink, the tube is patent and if no pink colour appears, then it is diagnosed as tubal blockage. The same test is to be repeated in the next horn. 2. Acquired defectsAcquired defects are caused by auma or infection, particularly at the time of parturition. Uterine infections cause embryo loss by the following ways:

direct killing of embryos,

changing the nature of uterine milk, accumulation of toxic products, release of PGF2 alpha which causes lysis of corpus luteum Producing chronic histological lesions.

Hence, infection should be ruled out before insemination. Subclinical infections may be identified by white side test and proper antibiotic should be infused. Recently, several alternative therapies have been introduced for treating endometritis in bovines If infection is mild, post-insemination antibiotic therapy may be useful. 3. Hormonal factors

i) Sub oestrus: It poses problems in identifying oestrus and proper time of insemination. The incidence of suboestrus in buffaloes varies between 10-11% in organized farms and between 30-60% in villages. No systematic studies have been conducted in buffaloes to explore various predisposing factors, but many hypotheses have been put forth like: the suboestrus may be due to lack of secretion of oestradiol by the mature follicle of due to need for a higher threshold for oestrogen. During summer months it has been postulated that CL does not regress fully and hence the animal become suboestrus. It may be overcome by oeotrus detection with teaser, or fixed time insemination PGF2a is to be administered at 6-16 days of oestrous cycle and insemination should be done between 72 and 96th hr after injection. ii) Delayed ovulation and anovulation: Normally ovulation takes place in cattle and buffaloes 10-14 hrs after the end of oestrus. Delayed ovulation means ovulation at more than 24 hrs after the end of oestrus when most of the sperm cells lose their fertilizing ability resulting in failure of conception. In an ovulation, animal shows normal behavioural oestrus and ovarian follicle reaches preovulatory size, but fails to ovulate. It will be partly leutinized and regressed if not it become cystic. This is due to impairment in LH secretion. In suspected cases, the ovary should be examined gently for the presence of follicle on the day of oestrus, day 2 and day 10th of oestrus cycle. If follicle is present on day 1 and 2, and a CL is presenting on day 10 in the same place of the ovary, then it is a case of delayed ovulation. Whereas in an ovulation of only follicle is present on all the 3 days of examination, it is anovulation. However the treatment is same for both the cases. Administration of LH of HCG (1500lU) at the time of insemination will be helpful in treating these conditions. iii) Defect in sperm transport: Deficiency of oxytocin, which causes contraction of uterus, may lead to falure of fertilization because the sperins may not reach the site of fertilization at proper time. In these cases administration of 10-20 IU i/v or 30-50 IU i/m of oxytocin just before insemination may be helpful. Clitoral massage after insemination may also cause secretion of oxytocin, and increased conception rate significantly (57% versus 45%) in crossbred zebu heifers.

iv) Luteal insufficiency: If progresterone deficiency occurs, the uterine milk will not be of proper quality and can cause death of embryo, or due to alteration in oestrgen: progesterone ratio, the fertilized ovum will reach uterus early. It is difficult to identify such case clinteally. However, if one feels the other causes are ruled out, this condition may be suspected. Administration of 1500 IU of HCG or LH on the day of Al can cause formation of more luteal tissue and hence avoid deficiency of progesterone. Managemental Factors1. Nutritional factors

Vitamin A, phosphorus and protein have an important bearing on reproduction in farm animals. Protein inadequacy has an important bearing on survival of embryos and development of fetus in domestic animals. Feeding low protein diet has adverse effects on ovulation rate. In buffalo heifers 4.00 inseminations/conception is recorded in protein deficient as compared to 2.66 inseminations conception in normally fed animals. Similarly, a higher plane of nutrition has been reported to be associated with decreased fertility. High protein of energy intake have a stimulating effect n hepatic blood flow which influences the metabolic clearance of progesterone causing its decrease to an extent that may compromise embryonic survival and growth. Hence animals should be fed with balanced ration at proper quantity. 2. Post-partum breedingConception following breeding of cows and buffaloes at varying intervals after calving is associated with factors like involution of uterus, milk yield, season of calving, etc. In a normal herd, it seems desirable to breed cows and buffaloes at 45-60 days post-partum. There are chances that the embryo may die or fail to develop to full term when animals are inseminated before proper involution of uterus. Under pastoral conditions neither conceptions are observed when the cows and buffaloes were inseminated at 45-60 and 60-90 days post-partum, respectively. 3. Estrus detection The single most important problem limiting high reproduction efficiency in a herd is poor detection of oestrus. falsely recorded oestrus can mislead the inseminator and if the animal is inseminated, it is not only a mere wastage of money but also there is every chance of making the animal infected when insemination is dine at luteal phase, because under the influence of Progesterone, uterus has a very low resistance to pathogens. 4. Time of inseminationThe most important primary requisite to obtain high conception rate is inseminating cows and buffaloes at appropriate tine. Duration of oestrus in cow ranges from 12 to 24 hrs and in buffaloes from 12 to 30 hrs. Best conception rates were obtained if insemination was done at mid heat to late heat. Optimum conception rates were obtained in cattle and buffaloes when inseminations were done at 12-18 hrs and 16-24 hrs respectively, after the onset of oestrus.

If inseminations are done too early of too late, aging of gametes may lead to fertilization failure of atypical fertilization of embryonic death. Hence, animals should be inseminated at proper time. 5. Insemination methodInseminations should be done by a well trained person with all precautions from semen loading to deposition in female reproductive tract. The semen should be slowly deposited into cervix (in early heat), while in late mid heat or early late heat the entire quantity is deposited at the internal os of cervix of into the uterine horn having a follicle in the ovary on that side. Later procedure needs more skill to do without damage to the endometrium. 6. Temperament of animalsCows and buffaloes with nervous temperament may be restless of under stress at the time of insemination and require more number of inseminations/conception due to secretion of adrenaline which has an antagonizing effect on oxytocin. Hence, the gamete transport is impaired. Therefore, the animals which are to be treated gently without causing any excitation or stress to get optimum conception rates. Important:

Keep complete breeding records Do not bred young animals until they are sufficiently mature. Provide sufficient rest period between pregnancies, don't breed too early

in post partum period. Observe females carefully for oestrus signs in case of silent oestrus. Inseminate at the proper time adopting a proper method by a proper

person.Think AI will be successful if you consider it involves man machine and management.

dr-kedarkarki@hotmail.com