3.5 Repeat breeding & Anoestrus
Cows that are cycling normally, with no clinical abnormalities, which have failed to conceive after at least two successive inseminations.
In practice, some will have been inseminated at the wrong time, others may have pathological changes in the bursa or oviduct that are difficult to palpate, or undiagnosed uterine infections.
The major reasons for repeat breeding are:
- Genetics :Chromosomal or genetic abnormalities of parent and those defects that occur during the differentiation process may negatively affect fertility.
- Age : Higher incidences of repeat breeding have been seen in old cows. It is observed that fertility in dairy cows get better after the 1st or 2nd parturition, and then declines from the 4th and 5th.
- 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.
- 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.
- 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.
- 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.
- 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.
Repeat breeders can be divided into two groups:
1. Early repeats
Cows that come into heat within 17-24 days after AI.
In these animals the luteal function has been shorter than normal or typical for the physiological oestrus cycle in non-bred cow. In these cows the most probable event is either failure of fertilisation (delayed ovulation, poor semen quality etc.) or early embryonic death (delayed ovulation, poor embryo quality, unfavourable uterine environment, precocious luteolysis)
2. Late repeats
Cows that come into heat later than 25 days after AI.
In these animals the luteal function was maintained for longer than the physiological luteal phase in non-bred cows. Fertilisation and initial recognition of pregnancy probably took place but for some reason (inadequate luteal function, inadequate embryo signalling, infectious diseases, induced luteolysis) luteolysis was induced and pregnancy lost.
Treatment of repeat breeders:
Nutritional deficiencies have been described as causes of RBC. Diets containing higher concentration of inorganic iodine from 8-12 days before estrus improve the stimulation of the pituitary gland, reducing at the same time the RBC rate
Strengthening Estrus Detection
Inadequate and inaccurate estrus detection is frequently a cause of cows becoming repeat breeders. Since estrus detection is less than 50% on many dairy farms, there is a substantial need for accurate and efficient heat detection.
Assisted reproduction techniques
Abnormal implantation and transport of gametes are associated with endometrial defects, resulting in RBC syndrome. Certain assisted reproduction techniques, as in vitro production of embryos or intraperitoneal insemination, have been proposed to solve this syndrome
Disorders related to reproductive tract infections may be related to RBC syndrome and very often overlooked by clinicians. Prophylactic practices have been used, as the uterine administration of antiseptic solution
Scientific contributions report the utility of some alternative medicines, such as acupuncture or moxibustion, to reduce the incidence of RBC syndrom
These hormones have been used in RBCs to induce ovulation and exert the luteotrophic effect on the CL
GnRH (gonadotrophin-releasing hormone)
The administration of GnRH around the insemination time aims to accelerate and ensure ovulation in cows, acting directly on the pituitary, stimulating the secretion and release of gonadotrophins, such as LH and FSH, and promoting the preovulatory LH peak, which is essential for follicular dehiscence.
Progesterone is essential for implantation and maintenance of pregnancy. CL dysfunction decreases Pg concentrations and then negatively affects fertility
The luteolytic effect of prostaglandins has been used to treat RBCs. In this case, treatment aims to achieve better heat detection and to increase the number of cows in heat.
Preventing repeat breeder cows
- Serving cows at the correct time. This means that all staff should know the signs of heat.
- Ensure insemination techniques are as good as possible.
- Don’t start serving too soon after calving.
- Minimise stress at service.
- Extremes of nutrition are detrimental to the survival of embryo. Deficiency of selenium and vitamin E were reported to cause early embryonic death. Extended period of feeding estrogenic forages affects the embryonic survival.
- Reproductive history and gynaecological examination of the cow.
- Examine for the normal structure of the reproductive organs, nature of discharge.
- Tubal patency test by PSP dye.
- Microbial culture of vaginal discharge.
- Narrowing the exact cause is usually difficult.
Management of repeat breeder cow
- Specific treatments for conditions like endometritis, delayed ovulation may be carried out whenever suspected them as the cause. If specific cause was not identified the following guidelines may be followed.
- Bring the animal into positive nutritive balance.
- Use good quality semen having more than 50 per cent progressive forward motility.
- Inseminate the cow at right time of the estrum. Do AI twice at 12 to 24 hour interval.
- Follow proper AI technique.
- After AI, Clitoral massage or 100 micro grams of GnRH or 1500 IU of luteinizing hormone may be administered to stimulate ovulation.
- Skip the AI; administer 1 million units of penicillin in saline twice at 12 hours interval during estrum
- Flushing the uterus with normal saline with moderate pressure to remove cellular debris/ mild blocks in oviducts. Sexual rest for two consecutive cycles and breeding.
Anoestrus in Dairy Cows
The cow is not observed in oestrus either because she has not come into oestrus (not cycling) or because oestrus was not detected (cycling).
The cow does not come into oestrus because she has inactive ovaries.
The cow has normal cyclic activity, but is not observed in oestrus due to weak or absent oestrus behaviour, or insufficient observation.
If oestrus has not been observed in a dairy cow 60 days post partum the condition is defined as Post Partum Anoestrus (PPA), whether she is cycling or not.
Classification of anoestrus in cattle
Benifiting from the use of ultrasonography and growing knowledge of follicular dynamics in cattle the following classification of anovulatory status is followed
1. Anovulation with follicle growth up to the emergence stage
- Cows exhibit very small follicles that are growing only to the emergence phase and do not proceed further.
- Fairly common in cattle exposed to poor feeding conditions such as extensive pasture management in tropical zones.
- The underlying factor is inadequate FSH stimulation
2. Anovulation with follicle growth up to deviation phase
- Follicular growth takes place and proceeds through emergence and deviation but not lead to ovulation.
- A frequently reported form of anoestrus. Commonly occurs in the post partum period in lactating dairy and suckled beef cows.
- The characteristic signs of this conditions are small ovaries, with the absence of a corpus luteum or ovulatory size follicles. The ovaries however show continuing follicular growth in a dynamic wave pattern up to the deviation phase.
- The underlying physiological problem is an inhibitory effect of oestradiol on GnRH/LH pulses that does not allow the final growth or oestradiol production by the post deviation dominant follicle.
Anovulation with Follicle Growth to Ovulatory or Larger Size of Follicle
- Essentially the dominant follicle from the previous follicular wave persists and does not ovulate; consecutive follicular waves also do not reach ovulation. Cows with ovarian cysts (anovulatory follicular structures) therefore have ovarian follicular waves similar to those of cows that ovulate (normal cows) at the end of oestrus, but these follicles fail to ovulate.
Pathogenesis of anovulatory status/Anoestrus in cattle
Resumption of cyclic activity after calving is influenced by nutrition, body condition, suckling, lactation, dystocia, breed, age, month of calving, uterine pathology and debilitating disease. It is well established that poor nutritional status and Negative Energy Balance are responsible for the majority of Anoestrus cases in both dairy and beef cattle.
Treatment of anovulatory/Anoestrus conditions in cattle
Treatment is based on:
- Improvement in energy status- optimal nutrition during the transition period and during early lactation.
- Hormonal treatments- combined with increased energy supplementation or reduced suckling stimulus may also help to stimulate oestrus.
Most important is to base treatment on improving oestrus detection:
- Knowing what to look for
- Allowing enough observation time
- Frequent observations
- Easy identification of individuals
- Good fertility records
- Possible use of milk progesterone kits.
The control of oestrus and ovulation by the use of prostaglandins, gonadotrophin-releasing hormone or progestagens may ameliorate some of the problems of oestrus detection by helping the farmer to detect oestrus within a defined period.
Anovulation with follicle growth up to the emergence stage
In these cases, treatments with GnRH usually have no effect, as the follicles on the ovary do not have adequate LH-receptors to respond
FSH/PMSG treatment combined with improved nutrition can increase follicle growth.
- Start with PMSG (Folligon):
- 500-850 iu per cow of bostaurus type and crosses
- 300-350 iu per cow of bosindicus type
- Once the follicular growth is increased GnRH (eg. Receptal; 2.5-5m1) can be used to stimulate maturation and ovulation of the dominant follicle.
- Do not breed/AI in the first oestrus
Anovulation with follicle growth up to deviation phase
GnRH stimulation + induction of ovulation
Modified Ovsynch protocol– Second GnRH replaced by hCG (e.g. Chorulon; 1.500 IU).
Dairy cows can be successfully treated with simple or modified Ovsynch protocol as many anovulatory dairy cows have follicles of sufficient size and ovulatory capacity but do not have an LH surge.