Non-infectious Causes of Bubaline Abortions

Buffaloes are of high economic importance particularly for Asian smallholder farmers. Pregnancy losses due to early embryonic deaths [1] or abortion [2] are a major constraint in the successful completion of gestation and consequent profitable milk production in buffaloes. Embryonic mortality appears to occur later (Day 25-40) in buffaloes [1] than in cattle (Day 8-15) and embryonic deaths have been found to be higher between 28-60 days of gestation compared to fetal deaths after Day 71 in buffaloes. The term abortion is applied to pregnancy losses in buffaloes due to fetal deaths beyond Day 45 of gestation [2]. Abortions are defined as a ‘loss of pregnancy’ in the period between 42 (rectal examination for gestation diagnosis) and 260 days of gestation [3]. The losses due to abortion are significant and multifold. The first and foremost is the loss of the calf crop along with the production loss in terms of milk and meat. Furthermore, it can also result in prolonged uterine diseases and sometimes sterility [4]. Around 5-7% of detected pregnancies are lost during the fetal period in cows [5,6] reflecting that fetal deaths are a substantial cause of economic losses. The economic impact of abortions depends on direct costs and value of fetuses lost. Indirect costs include those associated with establishing the diagnosis, re-breeding animals that aborted, possible loss of milk yield and replacement costs if dam that aborted is culled [7]. In buffaloes, the incidence of abortion as reported in various studies varies from 1.51% to 7.1% (Table 1). The causes of abortion are multifactorial and can be infectious (bacteria, viruses, protozoa and fungi) or non-infectious due to physical, genetic/chromosomal, nutritional, chemical, drug-induced, hormonal and miscellaneous agents [8]. In bovines, abortions before the fifth month of gestation seldom result in retention of fetal membranes, whereas those occurring beyond the fifth month invariably causes retention of fetal membranes [9]. Abortions due to non-infectious causes can account for many undiagnosed abortions in cattle [10] and probably similar conditions exist in buffaloes. In this chapter, we present and describe various documented as well as probable non-infectious causes of bubaline abortions.

1. Incidence of Abortion in Buffalo

The observed fetal loss is far less than the actual incidence. The incidence of abortion in buffalo observed by different workers is listed in Table 1. Many abortions go unnoticed or undiagnosed and we always suspect fertility problems when female buffaloes are found open rather than embryo/fetal loss. The greatest risk of fetal loss is during the first trimester of gestation and then progressively decreases as gestation advances with a slight increase in the risk toward the last month of gestation [11]. Rabbani et al., [12] found a 5.99% abortion incidence in buffaloes, which is higher than 1.14 and 0.87% recorded by Ibrahim [13] and Khan [14], respectively. Further, Rabbani et al., [12] observed that the minimum prevalence of abortions was found in the 1st lactation (7.03%); then it increased as the parity increased, reaching the maximum level at the 4th lactation (32.03%). It has been reported that parity had significant influence on the incidence of abortion with the lowest in the first parity and the highest incidence in the second parity (5.11 to 10.60 %) in Murrah buffaloes [15,16].

2. Non-Infectious Causes of Abortion

Several non-infectious agents that can probably cause a substantial number of abortions in buffalo are described in the text as follows:

2.1. Trauma

Trauma appears to be one of the misleading causes of abortion, until it causes severe damage to the fetus. Accidental insemination of pregnant buffaloes during gestational estrus [25] can result in abortion. Intrauterine infusion of irritant solutions or antibiotics in pregnant buffaloes (misdiagnosed as non-pregnant via transrectal palpation) can culminate in embryonic death and abortion. Manual rupture of the amniotic vesicle or rupture of the fetal heart or large vessels by manual pressure on the amniotic vesicle during early pregnancy (60-70 days of pregnancy) will cause termination of pregnancy [8].

Manual removal of the corpus luteum (CL) of pregnancy in bovines invariably results in induced abortion. Because of the damage that can be inflicted on the uterus due to physical methods of pregnancy termination, the longer time taken and the unpredictability of resumption of estrus cyclicity, these methods are no longer advised in bovines [26]. Therefore, manual removal of the CL to bring the animal into estrus should be avoided and early pregnancy should be carefully evaluated. After the sixth month of gestation, abortion may not occur by manual enucleation of the CL particularly in cattle heifers [27]. Other physical causes for fetal death and abortion in bovines include displacement of the umbilical cord over the head and neck of the fetus or torsion of the umbilical cord causing fetal death by interference with the circulation of fetal blood [8]. Occasionally abortions in buffaloes are observed following severe transportation fatigue and systemic stress.

2.2. Heat Stress and Seasonality

Exposure to high ambient temperature is the major constraint in buffalo productivity in hot humid climatic areas. The effect of heat stress is aggravated when it is accompanied with high humidity. Vale et al., [28] reported problems of embryonic absorption and abortion in female buffaloes raised in the Brazilian Amazon valley, related to heat stress causing hyperthermia due to inadequate management. High ambient temperature causes fetal hypotension, hypoxia and acidosis resulting in abortion. Exposure of buffaloes to the hot conditions evokes a series of drastic changes in the biological functions that include depression in feed intake, efficiency and utilization of feed intake, disturbances in metabolism of water, protein, energy and mineral balances, enzymatic reactions, hormonal secretions and blood metabolites [29]. In the shade, thermoregulatory mechanisms function efficiently in buffaloes and perhaps more effectively than that in cattle. At the same time, buffaloes have a greater tolerance to cold weather [29]. Hansen [30] suggested that the effect of heat stress is mediated through damage to the oocyte, impaired protein synthesis and possibly impaired endometrial activity and that it not only affects pregnancy rates if it occurs at the time of fertilization, but also impairs pregnancy throughout its course. Buffaloes with high fever (> than 106°F degrees) for prolonged periods are at increased risk for abortion probably due to a hot uterine environment adversely affecting fetal viability. It is therefore suggested to treat and manage pain and fever in sick buffaloes to reduce the chances of abortion. Drugs such as flunixin meglumine or others that have a minimum effect on the fetus are a good option [26].

The effect of daylight length on reproductive seasonality in buffaloes, may be an important cause of poor fertility resulting in delayed puberty, silent estrus and long post-partum ovarian inactivity [31,32]. In buffaloes, the incidence of reduced CL activity is between 5 and 50% during the long daylight length period [33], therefore there is a reduction in progesterone levels and an increase in embryonic mortality [1,34]. In fact, it has been observed that embryonic losses were 20-40% in artificially inseminated and about 20% in naturally mated buffaloes, with a higher incidence occurring between 28-60 days of gestation conceived during the period of increasing daylight length [1,35-37]. Interestingly, a 7% embryonic mortality incidence was reported during the period characterized by decreasing daylight length [38]. In contrast to earlier reports, an embryonic mortality rate of 20%, was reported for buffaloes close to the equator [39]. However, no information is available regarding the incidence during periods characterized by decreasing daylight length in Mediterranean areas.

2.3. Genetic or Chromosomal Abnormalities – Defects of Embryo or Fetus

Genetic factors causing embryonic/fetal loss include single gene defects, polygenic abnormalities and chromosomal anomalies. Most genetic causes of abortion in farm animals are beyond routine diagnostic capabilities. The majority of them occur before pregnancy is diagnosed and therefore go undetected. Numerous congenital defects have been reported in ruminants, some of which result in abortion. Inbreeding has resulted in increased embryonic deaths, abortions and stillbirths because of greater concentration of lethal genes per zygote as compared to crossbreeding [8]. Certain genetic defects of the fetus may result in intrauterine death and abortion such as fetal anasarca and achondroplasia [8]. Abnormalities such as achondroplasia and anasarca have been described for buffalo [40,41]. An embryo or a fetus with chromosomal abnormalities such as monoploidy, polyploidy and nullisomy or other defects, may cause failure to develop beyond a certain stage [42] and results in early embryonic/fetal death and subsequent abortion. Fetal genetic abnormalities that may cause abortion are not very frequently diagnosed and these problems usually occur as an individual animal problem rather than as a herd outbreak. Such abnormalities may not cause a change in the outward appearance of the fetus yet may result in abortion because of the growing fetus' inability to develop properly in the uterus. Genetic abnormalities may also cause obvious physical changes in the fetus. A cytogenetic survey of aborted fetuses, stillbirths/neonatal deaths and congenital defects in various domestic animals revealed an overall incidence of 8.7% chromosome anomalies, particularly mosaicism [43]. Cytogenetic evaluation is only a recently developed technique in buffaloes [44] and many of the chromosomal abnormalities such as X-trisomy [45], X-monosomy, mosaicism and other [46] were known to affect buffaloes [44]. New probes are currently investigated to improve the chromosomal diagnosis [47].

2.4. Inadequate Nutrition and Trace Element Deficiencies

Various minerals (copper, cobalt, selenium, manganese, iodine, zinc, iron, etc.) can influence the reproductive performance of ruminants. Reproduction is generally diminished or ceases under adverse nutritional conditions. Severe starvation may result in abortion. Animals on a very low plane of nutrition abort as a protective mechanism to conserve their own body reserves [48]. Pregnancy toxemia due to deficiencies of energy is clearly reflected many a times during twin pregnancy in sheep and goat [49], however, such a clinical entity is practically non-existent in buffaloes. Dietary protein might be of some importance in maintaining the pregnancy. One group of workers found that when feeding two levels of protein to pregnant animals, there was increased calf mortality in the low-protein group and was associated with either dystocia or pre-maturity. They concluded that protein malnutrition in late pregnancy may be a factor contributing to neonatal mortality [50].

The processes involved in the maintenance of various feto-maternal nutrient exchanges and balance are complex and it is difficult to comment positively that deficiency of a particular nutrient is likely to terminate pregnancy conspicuously. Vitamin-A deficiency is more likely to result in weak, blind unthrifty calves rather than in abortion [7], however, premature deliveries or birth of a weak calf [51] may be seen. Female animals require more Vitamin-A than male, and the pregnant female apparently requires more Vitamin-A than the non-pregnant female. Vitamin-A deficiency causes keratinization of the vaginal epithelium and degeneration of the placenta leading to abortion [46]. If pregnancy goes to term, there are chances of dystocia and retained placenta. The current view on Vitamin-A and beta–carotene is that these have a role in reproduction as antioxidants, therefore protecting the maturation of the oocyte and the development of the embryo, thus helping in the successful maintenance of pregnancy [53].

Micro-mineral deficiency like iodine deficiency may cause weak or dead calves at term and abortion [54]. A lack of iodine indirectly influences growth rate, milk production and feed consumption with other deficiency signs such as poor conception rates, abortions, longer gestation periods and the birth of dead, weak or hairless calves [55]. Iodine deficiency in herds, leads to impaired fertility and an abnormally high abortion rate [56]. Subnormal serum protein bound Iodine (PBI) has been found to be associated with infertility in buffaloes [57]. Zeedan et al., [55] suggested that iodine supplementation at 0.5 mg per kg DM intake /h/d in female buffaloes tended to improve reproductive parameters.

Selenium deficiency has been correlated with abortion as observed in cases of retained placenta, where selenium administration results in the expulsion of the placenta. Along with abortion, other reproductive disorders of ruminants that respond to selenium supplementation include retained placenta, still birth, early embryonic mortality, mastitis and metritis [58]. Zinc and selenium deficiencies have also been associated with abortion, fetal mummification, lower birth weight and prolonged labor [59,60]. Both zinc and selenium deficiencies were observed in anestrus Nili Ravi buffaloes in Pakistan [61] and many publications [62-65] have addressed the positive effects of selenium supplementation on fertility in dairy buffaloes. Buffaloes in areas with selenium deficiency are thus at increased risk of abortion.

2.5. Ingestion of Poisonous Plants

It is beyond the scope of this chapter to describe all the poisonous plants and chemicals that can result in abortion in bovines. A few of the common poisonous plants are briefly described. Most descriptions have been mentioned for cattle and presumably buffaloes would be affected similarly.

2.5.1. Nitrate Poisoning (Lowland Abortions)

Ruminants are especially vulnerable to nitrate intoxication because of the nitrate-reducing potential of rumen microbes [66]. High nitrate concentration in some plants may produce toxic reactions like methemoglobinemia, vitamin A deficiency, death of the fetus and sometimes of the dam. Locoweeds and Broom snake weed can cause abortions in cattle and sheep when ingested in large quantities. Consumption of lower quantities can result in deformed fetuses [67]. Abortions occur between 3 to 9 months. Cattle are therefore susceptible to both preformed nitrite such as from a fertilizer source and nitrate from nitrate-accumulating plants or fertilizer. The relatively toxic nitrite ion can be absorbed into the bloodstream, where it oxidizes normal ferrous iron (Fe2+) in hemoglobin to the ferric state (Fe3+) forming methemoglobin. Methemoglobin is unable to carry oxygen, resulting in hypoxemic stress in supplied tissues. Field cases of bovine abortion have been associated with forage containing as little as 0.52% nitrate and abortion usually is reported to occur with feeds containing 0.61% to 1.0% nitrate [68]. Common examples of nitrate-accumulating plants include Sudan grass, oat, wheat, corn, pigweed and Johnson grass. Heavy fertilization associated with cool, cloudy growing conditions is conducive to nitrate accumulation. Placental transfer of oxygen may be greatly reduced with consequent hypoxia and intrauterine death of the fetus in nitrate-poisoned cows. Further adverse effects of nitrite include its vasodilatory action and the consequent reduction in mean arterial blood pressure and oxygen tension [69]. Hypoxemia in late-gestation fetuses results in increased cortisol [70] and ultimately leads to abortion.

2.5.2. Mycotoxins

Ergot alkaloids, produced by the Claviceps genus, have been incriminated in various reproductive diseases. This fungus contains a large array of ergopeptine alkaloids that can cause abortion in cows and mares [26]. Ergot bodies are the source of physiologically active ergot alkaloids found in contaminated grains such as rye, barley, oat, wheat, fescue and brome grass. The natural alkaloids of ergots are also potent stimulants of uterine muscle [71]. The sensitivity of the uterus to ergot alkaloids varies with maturity and the stage of gestation. Exposure of the gravid uterus during late gestation elicits forceful, prolonged contractions with a marked increase in tone. Appleyard et al., [72] recorded that abortion occurred in 11 of 36 cows in late gestation 7 days after being placed on a rye grass pasture. Bovine abortion has been associated with the consumption of aflatoxin-contaminated peanuts as well [73].

2.5.3. Pine Needle (Pinus ponderosa)

Abortions and related problems caused by eating needles from Ponderosa pine (Pinus ponderosa) trees [74-76] result in multimillion dollar losses each year to the beef industry in the western United States [77]. Needles from the Ponderosa pine tree (Pinus ponderosa), lodgepole pine (P. contorta) and common juniper (Juniperus communis) cause abortion primarily when consumed during the last trimester [78]. Consumption by pregnant cows induces a premature parturition or abortion usually in 1 to 3 days but may be delayed for 2 to 3 weeks [76]. Feeding pine needles to buffaloes caused abortions as in cattle and aborted fetuses were alive, all buffaloes that aborted had a retained placenta, and calf survival was dependent on maturity at the time of parturition [79]. It has been mentioned that consumption of pine needles caused abortions in a majority of buffaloes in late pregnancy; the response increased with advancing stage of pregnancy, increased dose of pine needles and greater length of exposure [79]. Therefore, abortion due to the ingestion of pine needles can be a problem for buffalo farmers who raise animals in areas where ponderosa pine trees grow. The ingestion of pine needles causes abortion in buffaloes from 21 to 142 days counting from the first ingestion of pine needles and abortion is believed to be due to a toxic agent which is believed to be an anti-estrogenic substance.

Isocupressic acid (ICA) is the abortifacient ingredient in Ponderosa and lodgepole pines as well as in common juniper [78]. ICA is contained in green or dry needles, bark and branch tips. ICA such as acetyl-ICA and succinyl-ICA is classified as a labdane resin acid. All of these resin acids have induced abortions in cattle. The rumen microbes rapidly hydrolyze acetyl- and succinyl-ICA to ICA, the direct abortifacient. ICA levels were 0.8% and 2.0% (dry weight) in lodgepole pine and common juniper, respectively. The mechanism of pine needle abortion involves a profound constriction of the caruncular arterial bed [80]. Uterine blood flow in cows fed pine needles decreased progressively, declining to 25.5% of baseline by the day of premature parturition [81]. Evidence suggests that consumption of pine needles induces a progressive reduction in uterine blood flow to the gravid horn and that this reduction causes the onset of premature parturition accompanied by normal prepartal changes in steroid secretion [81].

2.5.4. Locoweeds

Locoweeds are several species of plants of the genus Astragalus and Oxytropis and their chronic consumption for a period of 6 weeks or more caused multiple reproductive problems including abortion, teratogenesis, fetal death, delayed placentation, deficient uterine and placental vascular development, hydrops amnii, hydrops allantois, abnormal cotyledonary development, decreased conception rate, reduced libido and diminished sperm production [82]. The toxic ingredient of locoweeds and the Swainsona genus of Australia is the indolizidine alkaloid swainsonine which interferes with oligosaccharide degradation and glycoprotein processing by inhibiting lysosomal α-mannosidase and mannosidase II. Resulting lesions are characterized microscopically by cytoplasmic vacuolation of cells in a variety of tissues [83]. Initially, cattle may be reluctant to graze locoweed but once started, they become habituated, often seeking it out while excluding appropriate forage from their diet leading to locoweed poisoning.

2.6. Administration of Abortifacient Drugs or Chemicals

Various pharmaceuticals have been proven to be abortifacients. In particular, the safety of giving anthelmintics to pregnant animals is in question. Prostaglandin analogues such as Misoprostol or Gemeprost (both synthetic Prostaglandin E analogues) can terminate pregnancy up to 24 or 60 days of gestation. Phenothiazenes or levamisole (during late gestation) and cambendazole or albendazole (early pregnancy), use of xylazine or high doses of acetylpromazine in the first half of pregnancy may cause abortion because of their adverse effect on placental perfusion [84]. However, xylazine did not affect buffaloes in late stage of pregnancy possibly because xylazine did not influence the myometrial activity of the pregnant uterus [85].

2.7. Hormonal Imbalance

2.7.1. Progesterone Deficiency

The deficiency of pregnancy maintaining hormone, progesterone has been considered for long as a cause of abortion in ruminants. Progesterone prevents uterine contractions that can lead to abortion or premature parturition [86]. In particular, cattle and buffaloes need luteal progesterone to maintain pregnancy; however, deficiency of progesterone is more a cause of mid or late abortion. It is usual for clinicians to administer a dose of exogenous progesterone in cases of impending abortion in cattle and buffaloes, but this need to be carefully viewed. Administering a dose of progesterone could be dangerous when the cervical os has dilated and the autolyzed fetus is in the process of delivery. The administration of progesterone in such cases can lead to fetal maceration and delay in delivery of a dead fetus [26].

2.7.2. Accidental or Faulty Administration of Hormones

Hormones such as prostaglandins, estrogens and corticosteroids have been suggested for termination of pregnancy in buffaloes [87], therefore, accidental administration of these hormones during the pregnancy can lead to abortion (Table 2). High glucocorticoids in the blood as a result of stress because of environment, management, transport or disease are likely to induce abortion in many domestic animals including buffaloes. Abdullah et al., [88] studied the effect of oxytocin on reproductive traits of buffalo in urban and rural areas and observed that more than 50% of dairy animals receiving oxytocin for milk let down tended to abort, mostly in early stages of pregnancy; there was 22% incidence of uterine prolapse in such buffaloes. Recently, it has been documented in buffaloes and cattle, that calves fed the milk of animals treated with oxytocin, showed low conception rates and increased abortion rates after reaching maturity [89,90].

2.8. Miscellaneous Causes of Abortion

These include twinning, allergies, umbilical cord torsion, parity, anaphylactic reactions. Twinning is an important cause of abortion in mares and less common in bovines. In mares almost always twin pregnancies result into abortion at four months or later. This occurs because of a lack of placental area (due to diffuse placentation) in the uterus. Much work has been done on twin reduction in mares during the past few years using ultrasonography [92], but not in bovines. Twinning in cattle is associated with a higher rate of premature births, abortions, dystocia and expulsion of dead or weak fetuses at term [93].

Allergies and anaphylactic reactions may cause abortion in cattle which mostly follow within 2 to 3 days of anaphylactic reactions. In cloned animals, characteristic anomalies such as increased birth weight, placental abnormalities and immune deficiency have been linked to abortion in many species including bovines [94]. Furthermore, abortion rates and neonatal deaths are consistently higher in animals generated by nuclear transfer than those by in vitro fertilization or artificial insemination [95]. In cloned embryos, global DNA hypermethylation has been reported [96] along with aberrant gene expression [97]. The latter observation may be related to DNA methylation that can directly and indirectly block transcription leading to aberrant gene expression and possible subsequent fetal abortion and developmental abnormalities in cloned animals [98]. Cloning in buffaloes is becoming increasingly popular [99-103] and thus the likelihood of possible abortions does exist. Other possible miscellaneous causes of abortion are lymphocytoma and abscess where the uterine wall is extensively involved.

3. Diagnosis

Despite the worldwide prevalence of abortion in bovines, diagnostic laboratories can usually identify specific etiological agents only in half of the specimens submitted [104-107] with a diagnostic success rates of only 25–30%, which confirms the fact that determining the cause of abortion can be a difficult task [7]. Abortion frequently results from an event that occurred a week or even months earlier and the cause, if it was ever present in the fetus, is probably undetectable at the time of abortion. In a large number of bovine abortions, pathognomonic gross lesions are uncommon and many times may be obscured by autolysis as the fetus remains in the uterus for variable periods of the time. Toxic and genetic factors causing fetal death and/or abortion are not discernible in the specimens available for examination and finally, many causes of bovine abortion are unknown or at present there are no useful diagnostic procedures for their identification.

The preferred specimens for diagnosis include intact aborted fetus, placenta, vaginal/uterine discharges and serum samples from the aborted dam. Physical appearance of fetus and fetal membrane should be noted along with approximate age of the fetus. Detailed history of the aborted dam should be recorded. The fetus and placenta should be placed in a double set of heavy duty plastic bags to prevent leakage, then packed in ice (but not frozen) along with any blood samples in a good quality, leak proof cooler [108]. Farmers must be advised to collect the aborted fetus and at least part of the placenta, place them in plastic bags without washing and refrigerate them or put them on ice to submit to a diagnostic laboratory.

4. Prevention and Control

The first and foremost approach in prevention and control is to investigate the cause of abortion and manage accordingly. If sporadic abortion occurs, then a full laboratory investigation is probably unnecessary. If abortion exceeds 3-5% of herd, it is important to consider stillbirths and premature calvings or number of abortions in a rapid succession and then a thorough investigation should be implemented.

4.1. Management to Reduce Abortion by Physical Trauma and Mycotoxins

Physical trauma in buffaloes can originate during transportation [109] and at markets [110,111], however, until they are severe they are seldom a cause of abortion. Care should be exercised in transporting pregnant buffaloes especially during late gestation as accidental fall or severe stress could result in abortion. Four of the five cattle heifers transported to Sudan aborted due to severe stress [112]. As far possible proper housing and provision of sufficient space for buffaloes minimizes the stress. Reproductive trauma likely to result in abortion due to fetal damage can arise out of manual enucleation of the CL, undue pressure/rupture of the amniotic vesicle in a pregnant animal and intrauterine infusion of irritant substances in a pregnant animal and thus such practices should be avoided and transrectal palpation should be done gently and carefully.

The prevention of effects of molds and mycotoxins in dairy cattle has been explained in detail recently [113] and these can be applied for buffaloes. Briefly avoiding high temperatures and keeping moisture levels below 15% in stored grains and hay reduces the growth of mold and mycotoxins harmful for dairy cows [113]. The addition of mycotoxin binders such as charcoal, silicates or complex indigestible carbohydrates has also been suggested by these authors to reduce the level of mycotoxins.

4.2. Management of Heat Stress and Seasonality

Harsh climate of subtropical regions like India severely affects reproduction in dairy animals. Buffaloes are severely affected by these climatic conditions and modifications must be made to meet the needs of the animals during the summer months. It is possible to modify the microenvironment to enhance heat dissipation mechanisms and manage the high humidity. Management strategies include providing shade, sprinklers, fans, etc., [114]. A strategy to reduce the effect of heat stress on reproduction may involve the treatment of anestrus buffaloes with antioxidants and melatonin during summer season [115,116]. Reducing metabolic diseases may further enhance the ability to improve reproduction during the summer months. Some simple feeding and nutritional strategies can be implemented to reduce the negative effects of summer stress on reproduction. Feeding dietary fat (rumen inert/rumen bypass) remains an effective strategy for providing extra energy during a time of negative energy balance. Administration of exogenous hormones either alone or in different combinations has been tried by different workers with varied degrees of success to manage summer infertility [114].

4.3. Adequate Nutrition to Prevent Abortion

Proper balancing of the nutrients intake in the form of protein, carbohydrate, fat, minerals and vitamins are necessary for the wellbeing of the dam and the fetus. Under field conditions, the supplementation of mineral mixture is not a very common practice. The intake of minerals through feeds and fodders is taken as an index of total dietary mineral supply and it is compared with the recommended requirements. Most of the farmers use domestic salt and molasses. Mineral mixtures for bovines are generally commercially available under various trade names. Providing a good nutrition pre and post-partum is a good measure in preventing abortion related to nutrition and early return to cyclicity in dairy buffaloes [16]. This simple measure will have a positive effect on lactation stress and may also shorten the duration of the negative energy balance period.

4.4. Prevention from Ingestion of Poisonous Plants

The ingestion of certain poisonous plants may result in abortion. It is important to identify potentially dangerous plants and either remove them from the premises or limit access of female buffaloes to such plants.

All genetic defects are not lethal and cause abortion. Some abnormal fetuses will survive to term which is economically not useful for the future of the breeding herd. Animals, both male and female, that produce calves with birth defects should be identified and eliminated from breeding programs to prevent future problems.