Repeat breeding syndrome in dairy cows

Introduction

Animal’s reproductive ability is one of the key elements in a dairy herd. Production of one calf crop per year provides maximum profit to the dairy farmers. Good reproduction and good production are just like two sides of a coin for making the dairy enterprise profitable.

The productive life of a cows starts with parturition which is the chief event of reproduction. After that the cow needs regular cycles of conception and calving to begin consequent lactation which is the key component of her productive life.  Hence, for a successful dairy farming reproductive performance of the dairy animals play a very crucial role. Therefore, the reproductive problems that ultimately leads to reproduction failure needs to be diagnosed and checked as early as possible for optimal production and profit in the farm.

One of the major loss making reproductive problems in dairy cattle prevalent at field level is existence of a large number of repeat breeder cows.  A repeat breeder is a cow that has normal estrous cycle, is free from palpable clinical abnormalities, has no abnormal vaginal discharge, is less than 10 years old, has calved at least once but has failed to conceive after at least three or more consecutive inseminations. In a simpler term, in case of repeat breeding cows will come to heat regularly but not succeed to conceive after successful mating. Repeat breeding causes financial loss in terms of repeated inseminations, treatment, cost of feeding without production, production loss due to delayed conception.

Causes of Repeat Breeding (RB) Syndrome

The aetiology of RB appears to be multi-factorial. The reason may be genetic, environmental, infections, altered ovarian activity. All these etiological factors ultimately results into either failure in fertilization or embryonic death that leads to repeat breeding. T

The major reasons for repeat breeding are:

1. Genetics : Chromosomal or genetic abnormalities of parent and those defects that occur during the differentiation process may negatively affect fertility. For example Repeat Breeding has been noticed in cows with chromosomal abnormalities as translocation 1/29 or trisomy X (Roberts, 1971; Lafi & Kaneene, 1988; Bruyas et al., 1993). Factors like inbreeding, aged gamete also may provoke genetic defects leading to repeat breeding. There also exists breed difference in occurrence of repeat breeding in cattle. The incidence of repeat breeding is mostly prevalent in Jersey and Holstein cross bred cattle in our country. 
2. Age : Effect of age on fertility is commonly reported as negative (Hodel et al., 1995). Higher incidences of repeat breeding have been seen in old cows (Hewett, 1968). It is observed that fertility in dairy cows get better after the 1st or 2nd parturition, and then declines from the 4th and 5^th (Dominguez, 1989).
3. Uterine infection and repeat oestrous cycles : The uterine environment encourages the normal embryonic development. Hence, any disorder or defects like uterine infections, endometritis, pyometra, metritis etc adversely affects the survival of the embryo causing embryonic death which is also one of the major reasons for repeat breeding. Francos (1979) noticed that from 3.5 to 5.7% of cows suffering from metritis had repeat estrus. Uterine infections negatively influence the uterine and cervical postpartum involution, follicular development, causes embryo mortality and repeat estrus rates (Lewis, 1997, Santana et al., 1998).
4. Anatomical defects of the genital tract : The reproductive tract of cow offers a appropriate atmosphere for oocyte growth, sperm transport, fertilization and implantation. Anatomical or functional alterations of these structures can compel gestational failure and repeat breeding.
5. Improper ovarian function : The problem of ovarian cysts in dairy cows is a serious reason of reproduction failure. Cystic ovarian degeneration (COD) is a cause of repeat breeding in cattle. Delayed ovulation, anoestrus are also linked with this problem. Luteal inadequacy resulting into progesterone deficiency may provoke repeat breeding syndrome.
6. Nutritional causes : The conception of the cows is associated with body weight. Mandatory weight which cows should achieve before breeding is for indigenous and jersey cross heifer 240-275 kg and for HF cross heifer 260-290 kg. Underweight animals show poor rates of conception. Balanced feeding (energy, fat, protein, vitamins and minerals) is the solution for this. The trace minerals particularly copper, cobalt, iron etc. are requisite for steroidogensis. Supplementing trace minerals and Vitamins A, D₃and E, can assist in treating the problem of anoestrus/repeat breeding dairy animals (Garg et al., 2008).
7. Artificial insemination : Any disorder at any action involving bull preparation, artificial vagina preparation, semen collection, semen processing, storage, thawing, post-thaw handling of semen, incorrect insemination in relation to stage of oestrus may result into repeat breeding. If animals are not inseminated at accurate time, it may cause conception failure. We should inseminate the indigenous cows according to AM.-P.M. rule i.e. if a cow comes in heat in morning, she should be inseminated in the same day evening and if came to heat on evening she should be inseminated on next day morning. The exotic/crossbred should be inseminated in mid to late heat. It is better to give double insemination should always be done with the gap of 12-24 hours after first AI in crossbreds.

Precautions to check repeat breeding problem

Repeat breeding is a very widespread problem of dairy cattle which causes economic loss to the farmers. Always prevention is better than cure. The following precautions may be taken to minimize the incidences of repeat breeding in cows.

1. Maintain breeding record properly
2. Avoid overcrowding especially at the time of AI.
3. Mineral mixture supplementation should be an integral part of diet @ 2% of ration.
4. Provide the animals clean water to drink.
5. Provide as much as cool climate to the animals during summer especially to crossbred animals. Heavy plantation around the farm, sprinkling water, bathing and roof painting will help to keep the animals cool and healthy in summer.
6. Animals with congenital defects of ovary, fallopian tubes or uterus should not be inseminated. These diseases are transmitted to next generations. Therefore, such animals should be culled immediately.
7. Underweight (less than 250 kg), malnourished, anaemic animals should never be inseminated.
8. Overfeeding of oil seed cakes to dairy cows should be avoided since it can enhance embryonic mortality.
9. Do not feed mould infested grains and green fodder and soiled wheat straw to dairy cows.
10. Cows showing turbid or discoloured mucus discharge should not be inseminated and should be checked for any uterine infections and treated accordingly.
11. Avoid putting the straw back into the liquid nitrogen cylinder once after it has been taken out. Once straw has been taken out, it should be used immediately or throw away.
12. To avoid contamination, the AI gun should never be pulled out of the vagina and reinserted into it.
13. Only efficient trained personnel should do artificial insemination.
14. Never use bulls with known genital infections for AI.
15. Do not use same bull again and again for breeding in same cow.
16. Do not use a bull for AI with his own daughter to check inbreeding. Maintain the record properly and rotate the breeding bull among the dairy farmers minimum after every 3rd year to check inbreeding.
17. Met oestrus/Post oestrus bleeding indicates the culmination of the heat and animals should never be inseminated at that time.
18. Use hormonal treatments judiciously only when required.

References

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2. www.elearnvet.net TANUVAS, 2011.
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5. Francos G. The relationships between the incidence of endometritis and repeat breeders in dairy herds. Refuah Veterinarith 1979;36:131-134.
6. Bruyas JF, Fieni F & Tainturier D. Le syndrome “repeat-breeding”: analyse bibliographique 1º partie: Étiologie. Revue med vet 1993;144:385-398.
7. Roberts SJ. Veterinary Obstetrics and genital diseases (Theriogenology). Published by the author, Ithaca New York, 1971, 496-506.
8. Lafi SQ & Kaneene JB. Risk factors and associated economic effects of the repeat breeder syndrome in dairy cattle. Vet. Bull. 1988;58: 891-903.
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10. Domínguez JC. Fisiopatología puerperal de la vaca. Bovis 1989;29:11-20.
11. Management of Repeat Breeder Cows and Breeding Records, Puja Mondal, http://www.yourarticlelibrary.com/

Source: Rajalaxmi Behera*, Ajoy Mandal*, Adhikari Sahu**, Saroj Rai*, M. Karunakaran* and T. K. Dutta*

* ICAR-National Dairy Research Institute, ERS, Kalyani, West Bengal

**ICAR- Central Institute of Freshwater Aquaculture