A phantom cow (फैंटम काउ) is a cow which has had one insemination and does not return within 35 days post-insemination but is found to be not pregnant.
The “Phantom Cow” Syndrome is a term used to describe cows that do not return for a second insemination from 18 to 24 days after the first insemination even though a conceptus can neither be seen ultrasonographically at 28 days post-insemination nor palpated per rectum at 35 to 42 days.
Progesterone profiles in these cows are very similar to those seen in pregnant contemporaries inseminated on similar dates. In a dairy farm, a proportion of cows that were retrospectively diagnosed as not pregnant until their first insemination was not re-submitted for a second insemination within 24 days.
A colloquial term, Phantom cows, has been assigned to this syndrome. They are defined as cows that:-
- are inseminated early in the artificial breeding period.
- are not detected in oestrus within 24 days of the first insemination.
- are retrospectively diagnosed as not pregnant to the first insemination.
The normal oestrous cycle of a cow is of 18 to 24 days duration, with an average of 21 days. It could be presumed that cows not conceiving to the first insemination should have returned for a second oestrus within 25 days.
Cows have been categorized as pregnant to the first service (Pregnant), returned to service 2 to 17 days later (Short Return), returned to service 18 to 24 days later (Normal Return), or were not pregnant and did not return within 24 days (Phantom cow).
While there was a large degree of variation, it is also of interest that 88% of the Phantom cow could broadly be classified into four categories.
- cows that returned to oestrus between 25 and 49 days after insemination and were detected in oestrus (Long return – detected).
- cows that appeared from milk samples to ovulate and/or show oestrus between 25 and 49 days after insemination but were not detected in oestrus (Long return – not detected).
- cows with an abnormal hormone profile where there was an extended period of non-luteal progesterone concentrations after the first insemination indicating either an anoestrus state or a prolonged non-luteal period (Anoestrus/ Prolonged non-luteal period).
- cows which were observed as pregnant at the early pregnancy diagnosis but were found at the 13-week examination to be not pregnant (Lost pregnancy).
Other categories included:-
- cows with no evidence of a return to oestrus within 49 days of the first insemination (No return within 49 days).
- cows appearing to have been missed in oestrus around three weeks after the first service (Missed heat);
- cows with an infection in the reproductive tract (Pyometra);
- cows with a cystic ovary (Cyst);
- and cows with substantial uterine adhesions (Adhesions).
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COMMERCIAL DAIRY FARM S STUDY RELATED TO PHANTOM COW IN INDIA:-
The Phantom Cow Syndrome is a major cause of sub-fertility in Indian dairy herds. A study in four commercial herds found that 22% of inseminated cows not pregnant to the first service did not return for a second service within 24 days. These cows have been defined as Phantom Cows.
- The fate of this Phantom Cow is that only 24% are likely to be pregnant to artificial insemination, 55% pregnant to the bull, and 21% remain not pregnant 21 weeks after the Mating Start Date (MSD).
- The Phantom Cow Syndrome is made up of many conditions but may be categorized into nine categories. Of these, four categories make up 88% of the observed cases.
- The most common category (39% of Phantom Cows) comprises cows that have a long estrous cycle after insemination, and are detected in oestrus 25 to 49 days after the first insemination.
- Another group of cows (21% of Phantom Cows) also appear to have a long estrous cycle, and they are not observed in oestrus and have not been served a second time within 49 days of the first insemination. These first two categories may represent embryo mortality.
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A proportion of cows (19% of Phantom Cows) have a period of either anoestrus or an extended non-luteal phase. They are unable to show oestrus while they remain in this state.
- There was an observed pregnancy loss between cases observed pregnant at an early pregnancy diagnosis that subsequently were diagnosed not-pregnant at a 13-week examination (9% of Phantom Cows). This level of occurrence is similar to previous reports.
- Other categories of the Phantom Cow Syndrome (date (MSD); the protein % of milk production; age; herd; carryover cows; retained fetal membranes and vaginal discharge; and the diagnosis and treatment of anoestrous cows.
These risk factors have been seen in Phantom Cows. The importance of each risk factor may differ for each category but strong factors included diagnosis and treatment before the first insemination, the interval from calving to the mating start date (MSD), the protein % of milk production, and herd.
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- Cows that were diagnosed as anoestrus before the MSD (and treated with a progesterone based protocol) had a greater risk of becoming Phantom Cows than cows that were inseminated without any prior treatment (27% vs 13%). Cows treated with a single injection of prostaglandin to induce the first oestrus had an intermediate incidence of Phantom Cows compared to cows that were not treated (17% vs 13%).
- The ability to resynchronize Phantom Cows was determined by progesterone concentrations between days 13 and 22 following insemination. Only 5% of cows treated with prostaglandin to synchronize oestrus could be resynchronized, whereas 47% of treated anoestrous cows could have been resynchronized.
- The two previous points contend that cows treated with a prostaglandin estrous synchrony protocol are likely to have a greater incidence of Phantom cows than normally cycling cows, and these cows are less able to be resynchronized. These observations, if repeated, may need to be considered before recommending a prostaglandin synchrony protocol.
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Subcategories of Phantom cows:-
There are 89% of the Phantom cow cases subcategorized as Long Return, No Return or Anoestrus. The proportion of Phantom cow classified as Long Return are associated with the herd and also physiological state before the first service.
It should be of major concern to the Indian dairy industry that 39% of the dairy cows population are not confirmed pregnant to the first insemination and do not return for a second service within 24 days. An understanding of the factors associated with this phenomenon is crucial to improving the reproductive performance of dairy cows.
There are associations of the Phantom cow syndrome with age, the interval from calving to MSD, BCS at calving, and intervention according to the physiological state before the first service.
It is likely that a major cause of the Phantom cow syndrome is due to the failure to detect a return to oestrus. These cases would be included in the No Return subcategory as they will have a CL on an ovary but will not have been detected in oestrus.
The cows that had a return to service interval between 25 and 39 days (Long Return) may have abnormal luteal function resulting in a prolonged oestrous cycle. Within the Phantom Cow population, Long Returns were more common in cows in the An-CIDR and No Treatment groups than the PG treatment group.
Long return intervals after a period of post-partum anoestrus have been observed generally. The greater incidence of anoestrus in younger cows and those calving in a low BCS concurs. Phantom cows are common among commercial dairy herds and are primarily made up of cows exhibiting a delayed return to service, with non-returning (possibly caused by embryo mortality or failure to detect oestrus) and anoestrous cows also contributing significantly to this phenomenon.
Treatment with prostaglandin before the first insemination reduced the incidence of delayed return to service, but this treatment is associated with an increased proportion of non-returning cows.
The risk of a high incidence of phantom cow syndrome increases with a herd history of large condition loss post-calving, metritis, high non-cycler rate, high blood NEFA levels post-calving, low BCS at mating, metritis, and BVD.
PREVENTIVE MEASURES FOR PHANTOM COW SYNDROME:-
- The single most important preventative measure is to calve cows down to allow them sufficient time to recover before the next mating season. This minimizes the risk of anoestrus and of becoming a Phantom Cow.
- All cows diagnosed as anoestrus should be treated before the MSD and should be resynchronized as is currently recommended. Anoestrous cows would still be likely to have a greater incidence of Phantom Cows, and further work is required to develop appropriate preventative strategies and improved treatments.
- The analyses of risk factors have identified the protein composition of milk as a strong factor in the incidence of both Phantom Cow and cows that are anoestrus before the MSD. More research is required to understand these relationships, particularly if protein composition relates the physiological state of the cow.
- It is noteworthy that oestrous detection errors, as well as gross pathology of the reproductive tract (infections etc), are of minor significance compared to the long oestrous cycles and possible embryo mortality. Understanding the causes of long oestrous cycles and embryo mortality may increase the number of cows pregnant to the first service, as well as increase the number of nonpregnant cows is served again within 24 days.
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