By Dr.Haresh Chaubey, Dairy Consultant.
Reproductive disorders and associated infertility among cattle and buffalo pose serious economic
loss to farmers in terms of low returns and veterinary expenses. Sincere and concerted efforts are
required to apply promising reproductive technologies at field conditions in large scale to maximize
the reproductive efficiency of milch bovines. Tis requires matching of genotypes to the production
environment, together with appropriate husbandry practices, in order to ensure that the intervals
from calving to conception are short and the rates of conception to natural or artificial breeding
are high. For better economic efficiency and competitive superiority of dairy farming, a thorough
knowledge on reproductive efficiency indicators, their application in the routine farm operations and
overall improvement of specific reproductive parameters are at most important.
The demand of milk and milk products in India is projected to increases to 191.3 MMT in
2020. At the existing rate of growth in milk production, in next years, supply is likely to fall short of
the demand. To fulfill the gap we need to improve the individual animal’s productivity, which would
need interventions at genetic, nutritional and managemental levels. Te ‘calvable’, but “uncalved”
population of milch animals account for approximately 10% of the total breedable population. If
these milk “producible, but not producing” animals could be given due attention to make them
pregnant, then the annul milk production of the country can be increased by at least 10%. Te
profitability of milk production from cattle and buffaloes depends to a large extend on the efficiency
of reproduction. Maximizing reproductive efficiency requires the matching of genotypes to the
production environment, together with appropriate husbandry practices, in order to ensure that the
intervals from calving to conception are short and the rate of conception to natural or artificial breeding
are high. Te reproductive cycle of dairy animal include follicle development and maturation, onset
of oestrus, successful coitus/insemination, ovulation, fertilization, implantation, development and
delivery of normal foetus and its membranes, proper uterine involution and cleansing, resumption
of ovarian cyclicity and estrus expression. In a lifetime, 8-10 such cycles are expected to occur in
dairy animals. Anything interfering with the routines of this cycle makes the animal infertile. Te
common reproductive problems can be divided into some major categories which include functional
disorders, infectious disorders, genetic disorders and other miscellaneous disorders. Te major
reproductive disorders that are economically important are repeat breeding, anestrus, retention of
foetal membranes and uterine infections. Tese are discussed here in detail.
1. REPEAT BREEDING (RB) ———-
A repeat breeder cattle of buffalo is defined as one that has apparently normal genitalia without any abnormal discharge from genital tract and with normal estrous cycle and estrous period but fails to conceive afer three consecutive inseminations/services with fertile semen/bull. To consider cattle/ buffalo as repeat breeder, it should be ruled out that there is no clinical infection and the insemination was done with good quality semen at proper time by qualified personnel. Since RB is a syndrome and may be due to multi factorial etiology, no single technique or method can be used to diagnose the cause. Examination of the suspected animal at various intervals may be useful to rule out certain conditions and to indentify the underlying cause.
Managemental and therapeutic approach ———–
Once the animal is considered as repeat breeder, the cause should be identified. Since RB is a syndrome and may be due to multi-factorial etiology, no single technique or method can be used to diagnose the cause. Examination of the suspected animal at various intervals may be useful to rule out certain condition and to identify the underlying Cause.
Ovulation abnormalities: ——
Normally ovulation takes place at 10-12 hrs after the end of oestrus
in cattle and buffaloes. Abnormalities in ovulation include delayed ovulation and anovulation. Te
differential diagnosis between delayed ovulation and anovulation can be made by examination per
rectum of ovaries of suspected animal on the day of oestrus day 2 and day 10-12 of the oestrus cycle.
If the follicle is present on all three examinations, the case is diagnosed as anovulation, while if the
follicle is present on first and second examination and a corpus luteum (CL) at the same place on and
examination, the case is delayed ovulation. Once diagnosed, delayed/anovulation can be treated by
administration of LH or hCG (eg. Chorulon, lntervet) 1500-3000 IU or GnRH 10-20 µg (eg. Receptal,
Hoechst) on the day of estrus.
Subclinical infections: ————-
In subclinical infection of the reproductive tract, there may not be any
visible abnormalities in discharge except from occasional whitish flakes, and animals experience
normal cycle length. Because of these subclinical infections, uterine environment is altered, which
may interfere with embryo survival. White side test can be used to some extent to identify subclinical
infection. In this test, to 1 ml of genital discharge, 1 ml of 5% NaOH is added and heated up to boiling.
Appearance of yellow colour indicates infection. Uterine infection can be treated with wide range
of antibiotics, antiseptics, hormones and other alternative therapies. Post insemination antibiotic
therapy is found quite useful in this.
Defective gamete transport:————
It may be due to abnormalities in tubular genital tract or hormonal imbalance.. Tis can be easily diagnosed using the phenosulphonpthalene (PSP) infusion test. Several reports suggest that administration of oxytocin (5-10 IU) immediately afer insemination improves the conception rate, by facilitating sperm transport.
Luteal insufficiency:———–
Progesterone, secreted by CL, is essential for embryo survival. If the CL is not compositely formed, or if it is not functioning adequately, it leads to failure of pregnancy. lf other causes are ruled out, a RB animal can be suspected for this condition and can be treated with GnRH or hCG, 2-3 days afer insemination to improve the CL formation, at mid cycle to stimulate accessory CL information or at around day 17 to prevent the CL regression.
Fixed time insemination: In sub-estrus buffaloes and cattle, PGF2α can be used to bring
the animal into estrus, and insemination can be done at fixed time. Single dose PGF2α can be
administered at 16-5 days of estrous cycle or to those animals, which have mature CL as assessed by
rectal examination. Double injection of PGF2α at 11 days interval can also be employed and it avoids
the rectal palpation of CL. Fixed time insemination at 72 and 96 hr afer PGF2α administration may
yield higher conception rates.
Clitoral stimulation:—–
Mechanical stimulation of reproductive tract by massaging clitoris after
AI has been shown to improve conception rate by hastening the surge of luteinizing hormone and ovulation.
2. ANESTRUS———–
Delayed sexual maturity in heifers (prepubertal anoestrus) and absence of ovarian activity afer parturition is commonly encountered in buffaloes. Heifers should be managed properly to attain puberty before 18 months of age so as to obtain first calving at 2.5-3 years of age for economic reasons. Body weight attainment is more important than the age for onset of puberty. If the animal fails to exhibit estrus for longer period, excepting during pregnancy, called as anoestrus, affects the economy by prolonging the calving interval. This condition is generally observed after parturition (post partum anoestrus) especially under field conditions.
Factors associated with anestrus ———-
Under feeding:—–
In heifers, under feeding delays the onset of puberty and sexual maturity, where as in adults, it is characterized by irregular estrous periods and anestrus. Under feeding for prolonged period causes failure of proper follicular development, leading to follicular atresia along with loss of sexual desire or production of weak young ones.
Protein and Vitamin deficiency: ——-
Protein and Vit. A deficiency adversely affects reproduction in most species. Vitamin A deficiency is characterized by keratinization of epithelium, degeneration of placenta fetal death, abortion and retention of foetal membranes.
Mineral deficiency: ———
The deficiencies causing anestrus in cattle and buffaloes are mostly limited to phosphorus and trace elements. Te usual symptoms of phosphorus deficiency are delayed onset of puberty in heifers and failure to exhibit estrus in cows. Copper, cobalt, manganese and iron deficiencies are not uncommon and their deficiencies may affect normal reproduction.
Hormonal disturbances:——
Most of the hormonal disturbances causing infertility are secondary to basic nutritional, hereditary and other stress factors. It should always be remembered that indiscriminate use of hormones itself may lead to fertility
Diagnosis ——–
It is very important to rule out pregnancy before treating the animals for acyclicity. Body condition of the animal along with thorough gynecological examination can aid in prompt identification of underlying cause(s). Ovaries and tubular genitalia should be examined in detail and two successive examinations at an interval of 10-11 days are recommended. While examining, the following conditions have to be kept in mind.
1.Ovarian agenesis (Heifers; incidence very low) 2. Ovarian hypoplasia 3. Smooth, small ovaries with no palpable structures (true anestrus) – confirmed by two examinations of ovary at 11 days interval. 4. Large ovary(s) with fluctuating area (>2.5 cm) – Cystic ovary. 5. Corpus luteum in one or both ovaries – may be due to silent estrus, but pregnancy to be ruled out
Therapeutic approach ———
Successful treatment depends upon accurate diagnosis. For ovarian agenesis or ovarian hypoplasia, there is no treatment. Some cows with completely smooth non-functional ovaries do not show always encouraging results when hormones are used. Terapy for these cows should aim at correcting the underlying nutritional deficiencies or other systemic diseases.
a) Follicle stimulating hormone (FSH):——-
As the name indicates, the physiological role of this
hormone is to induce follicular growth. Once follicular growth is induced, the estrogen secreted by
the developing follicle induces an endogenous Luteinizing hormone (LH) surge for ovulation. But, in
several cases of anestrus, administration of FSH alone would not benefit, as ovulation is not ensured.
Administration of LH or hCG afer 48-72 hrs of FSH is also necessary to favour ovulation.
b) Progesterone: ——–
Administration of progesterone mimics the presence of corpus luteum and induces follicular growth and ovulation when withdrawn. Tere are several methods of administration of this hormone viz. oral, intra-vaginal, injection and ear implants.
c) Combination of hormones: —–
Several combinations of above said hormones (eg. progesterone
releasing intravaginal device-PRID; Norgestomet ear implants) are also used to augment fertility in
anestrus cattle and buffaloes. Recently, administration of GnRH and PGF2α has been reported to
induce estrus within 3-5 days of treatment. Tere are several protocols for induction of estrus in no cyclic animals, viz. Ovsynch, Heatsynch, Provsynch etc. Our experience indicates that conditioning the buffalo heifers with proper deworming and supplementation of vitamins and minerals improve the response to estrus induction protocols.
1. RETENTION OF FETAL MEMBRANES (RFM) ————
Retention of fetal membranes (RFM) is defined as the inability of a cow to shed the fetal
membranes even afher 12h of parturition. RFM predisposes cows to different peri-partum diseases
that includes but not limited to, mastitis, metritis and ketosis, and directly decrease the milk yield and
disease resistance. The reproductive consequences of RFM are due to postpartum metritis and include
an increase in the service period, days open, calving to conception interval and calving interval.
Preventive management of RFM ———–
Proper growth rates resulting in heifers calving at desirable body weight and selection of calving ease sires are the most important management considerations for prevention of RFM in heifers. Te strategy should focus on maintaining a healthy, contented and active cow prior to, during and after parturition. A balanced, limited ration during the 6-8 week dry period, sufficient daily exercise, sufficiently large, clean and comfortable calving areas and proper sanitation during the calving period minimize the chances of RFM and infection.
• Selenium supplementation, dietary or parenteral.
• Intramuscular injections of Vitamins A & D, 4-8 weeks prior to calving, if deficient.
• Maintenance of calcium: phosphorus ratio between 1.5:1.0 and 2.5:1.0.
• Administration of either Oxytocin (20-30 IU) or PGF2α immediately afer calving.
Therapeutic management of RFM ————
Te basic goal in any treatment of RFM is to return the cow’s reproductive tract to a normal state as quickly as possible. Tere are generally two methods of managing retained placenta, when no systemic involvements are present- manual removal and natural separation.
• Manual removal should be avoided, because of possible injury to the delicate lining of the uterus
resulting in uterine infection and associated complications.
• Try to detach the placenta by applying slight tension externally to the fetal membranes.
• Allow the membranes to separate naturally with or without the use of medication. Hormones
such as PGF2α and oxytocin may be used to hasten the process.
• Use of intra uterine infusions should be minimized and systemic treatment with long acting
antibiotics like Cefiofur is advisable.
• Partial retention may go unnoticed until complications such as metritis or pyometra develop.
These animals should be examined and can be systemically treated with antibiotics and locally with intrauterine medication (if unavoidable) by a veterinarian.
2. INFECTIOUS DISORDERS ((UTERINE INFECTIONS) —————
Uterine bacterial contamination in cattle is a dynamic situation, with regular contamination,
clearance of bacteria and spontaneous re-contamination during the first few weeks afer parturition,
rather than just contamination at the time of calving. A normal postpartum cow resolves uterine
infection by rapid involution to the uterus and cervix, discharge of uterine content, and mobilization of natural host defenses, including mucus, antibodies and phagocytic cells. If the immune status of the animal is altered, then the established uterine infection would continue to persist resulting in development of metritis of varying degrees.
Predisposing factors ———–
The risk factors that have been previously established for uterine infections include abnormal
length of gestation, stillbirth, twins, assisted parturition and RFM. Prepartum health status of the
animal plays a major role in predisposing the animal to development of post-partum uterine infection.
Nutrition:—
The energy requirements for maintenance and pregnancy of dairy cattle increase during the last month pre-partum, but during this time feed intake may be reduced. If the animal is not provided with energy dense diet it will lead to several complications that could predispose the animal for development of metritis during post-partum period. Te protein requirement for growth of conceptus also increases as pregnancy advances. It is important to maintain adequate levels of calcium, selenium, and vitamins A and E in the diet of cows.
Environment: —-
The effects of any stress are amplified in the transition period and attention should be paid to cow comfort, stocking rates and cooling in hot climates. During calving and few days afer, the cervix is dilated and the uterus, which is already irritated from the calving process, is exposed to a variety of infectious agents in the environment.
Assistance during calving: ——–
The cows should be assisted while calving, only if it is absolutely necessary. Unnecessary and improper assistance increases the chance of developing uterine infection. Interfering too early in the calving process may cause more problems than it solves. To avoid calving difficulty, it should be ensured that heifers have grown to adequate size before they are inseminated. Semen from calving-ease sires should be used for virgin heifers.
Peri-partum complications:————
The major production disorders during peri-partum period are milk fever, ketosis and displaced abomasum. Te peri-partum risk factors important for development of uterine infection include mainly dystocia, milk fever and RFM. Other risk factors for metritis include stillbirth, twin births, primiparity and winter season.
Biomarkers for prediction of metritis ————
Behavioural markers:——
The feeding pre-partum time and bouts could be used as a behavioral
maker for predicting the development of metritis, since the cows that develop metritis post-partum
showed significant reduction in feeding time and bouts during pre-partum period (from 2 weeks
before calving).
Biochemical markers: ———-
During peripartum period, the non-esterified fatty acids (NEFA), β hydroxy butyric acid (BHBA) concentrations and plasma NEFA: total cholesterol ratio have been shown to be significantly higher in metritic cows compared to normal cows. In developed countries ‘on-spot’’ diagnostic kits have been developed based on the biochemical markers for the early detection of complications.
3P management strategy
1. Prepartum feeding and health care: ——-
The nutritional needs of the cow are satisfied throughout
the dry period with special attention to protein, energy, vitamins and minerals. It is critical that
dry cows do not lose weight during the dry period. Adequate tissue levels of proper vitamins and
minerals must be present prior to calving and throughout the postpartum period if uterine health
is to be maintained. However, it should be ensured that the cows are not over-conditioned. The desirable range of BCS (1 to 6 scales) during dry off and calving in cows and at calving in heifers is 3.5 to 4.5. Te marked body condition loss from the dry to near calving periods results in the increased occurrence of postpartum metabolic and reproductive diseases. Te over-conditioned cows spent less time feeding during transition period and increase susceptibility to metritis.
2. Peri-partum care:—–
Common calving difficulties including dystocia is due to various factors and uterine inertia. Cows with these problems should be handled properly by qualified personnel so that minimal damage occurs to the genital organs. RFM predisposes cows to different peripartum disease that include but not limited to, mastiffs, metritis and ketosis, and directly decrease the milk yield and disease resistance. To obtain better post-partum fertility, it is necessary to keep the incidence of metabolic diseases within the permissible level, since these diseases increase the risk of developing postpartum metritis in dairy cows. Among the metabolic disorders, milk fever is a problematic periparturient disease, as a result of its association with 8 other periparturient disease processes and its negative effect on postpartum DMI. Te transition cow management should focus on prevention of the negative effect of the inadequate nutrition (negative energy balance-NEBAL, protein imbalance, vitamin, micro-elements and mineral insufficiency) and to improve BCS, in order to allow a normal reaction of cows for the reproductive treatments.
3. Post-partum follow up: ——-
Management practices focused to ensure good health or
prevent serious post-partum disease conditions are very important in managing reproductive
performance. In most of the cases the infection is diagnosed when it becomes clinical, which
leads to more investment on therapy and takes more time to cure. The protocol for post-partum
follow up should focus on early disease detection by frequent animal observation and monitoring.
The practice of monitoring rectal temperature for at least the first 10 days post-calving is to
be strictly implemented to identify the possible problematic cows at an early stage. Depending
upon the visual appraisal (bright and alert or dull and depressed) and body temperature, further
evaluation (rectal/vaginal) is to be decided. Depending upon the results of each evaluation
criteria, a set protocol is to be established for therapeutic applications. The current approach in
addressing retained placenta and metritis in dairy cattle is to monitor body temperature and cow
behavior. If a cow’s body temperature exceeds 39.50C, then a systemic antibiotic is administered.
Procaine penicillin or Ceftiofur (long acting) are approved for treatment of metritis and have
been found to be efficacious. NSAIDs may also be used in combination with systemic antibiotics,
if deemed necessary based on animal evaluation.
GOOD PRACTICES FOR OBTAINING HIGH CONCEPTION RATE WITH AI
Frozen semen quality:—–
Superior quality frozen semen is an integral part of AI programme. In
order to achieve high post thaw semen quality, it is essential to obtain high quality fresh semen.
Quality semen from authorized and certified semen stations should be used for insemination.
Semen storage, transfer and retrieval: ——-
Once frozen, exposure of straws to temperatures above -130oC and recoiling results in irreparable sperm cell damage. Tis results in reduced sperm motility, viability and acrosomal integrity. Progressive motility of sperm is required for transport of spermatozoa from the site of deposition to the site of fertilization, while acrosomal integrity is essential for membrane specific recognition and binding of sperm with ovum. Hence, it should be ensured that the canister containing semen is well below the top of the tank neck.
Handling of straws and thawing: ———–
The straws should be removed from LN2 container using a
tweezers/forceps as quickly as possible (within 3-5 seconds) and shake to remove excess nitrogen.
There are several methods of thawing ranging from ice water to 750C for 12 seconds and thawing in
water at 370C for 30 seconds is generally advocated and the straws should be fully dipped in water.
After thawing, the straws should be wiped gently to remove water. If the air bubble is located in the
single plug (laboratory seal) side of the straw, then it can be cut with dean scissors. If it is located in
the middle of the straw, it should be moved towards the single plug side by shaking gently before
cutting. The straw should be gently placed in the gun and elided into the sheath and the sheath
should be secured with the gun tightly using ‘O’ ring. Before loading, the Al gun should be warmed.
There should be no gap between the cut end of the straw and the sheath otherwise part of semen may
remain in the sheath thus reducing the number of spermatozoa per insemination.
Selection of female for insemination: ————
Improper detection of estrus is the biggest bottle neck in artificial breeding under field conditions especially in buffaloes. It is essential that insemination should be done at proper estrus to obtain high CR. Tough the owner/herds man of the animal to be inseminated claim that the animal is in estrus, it should be confirmed by clinical/ gynecological examination. The arborization pattern (fern pattern) of cervical mucus can be used to predict the optimum time of insemination.
Time of insemination: —-
Thumb rule under field condition is that, if the animal exhibits beginning
of estrus signs in late night or early in the morning, it should be inseminate in the evening of same
day. If the estrus signs start at late morning/afternoon/evening then the animal should be inseminated
next morning. But, in case of buffaloes, recent reports suggest that the period from end of estrus to
ovulation is longer than that of cows. Hence, buffaloes can be inseminated in the late heat for better
conception rate.
Method of insemination:———–
All efforts to make AI successful using proper collection, handling and
processing of semen are worthless, if insemination is not properly carried out. Te cow or buffalo to
be inseminated should be restrained well; otherwise there is every chance to damage the uterus by Al
gun and/or improper deposition of semen leading to poor CR. Before introducing the gun, perineum
and vulval area of the animal has to be wiped properly to avoid infection carried through the gun.
Insemination gun should be inserted at 30-450 angle after opening vulval lips to avoid urethral
opening. In case of frozen semen, the site of deposition is the body of uterus, just next to the internal os of the cervix. After withdrawing the gun, uterus can be massaged gently as it may hasten the sperm transport.
Reference:On request.
