On average the HAF RESEARCH data show that there is little seasonal change in the number of cases of retained placentas (RP) in cows.
What is a Retained Placenta
RP occurs when the calf’s side of the placenta (the fetal membranes) fails to separate from the mother’s side. However, separation of the membranes normally occurs after the calf is born (early separation is one cause of stillbirth),so defining the time at which the membranes become ‘retained’ is not simple. The most commonly used definition is 24 hours after birth, but this is used because its easy to assess, not because there is no effect on cows which retain their membranes for 12 hours.
RP is a lot more complex than it first appears. This is because the single sign associated with RP, the presence of membranes at the vulva for too long after calving, has been associated with a vast range of different factors. These include breed, year, season, twins, age, fatty liver, insufficient selenium, too much selenium, and milk fever. Very little about the appearance of the retained membranes tells you about its cause, so the identified cause is often an assumption based on the balance of probabilities Each case of RP costs the farmer around Rs. 19550. This is partly because of the veterinary costs, but mainly because of the effect on milk yield and, most importantly, subsequent fertility
Diagnosis of the cause
- Membranes associated with either abortion or induction tend to be tough and slow to breakdown (which means they usually smell less!), but there is no other obvious connection between appearance and cause
- Most herds have an RP rate of around 5%. If the rate goes above this figure (especially if it goes above 10%), veterinary advice should be sought Treatment
- Around 40% of cases require no treatment.
- Manual removal should only be used if the membranes are very loose and never in sick cows.
- Early use of antibiotics may slow down the release of the membranes
- The best plan is to observe the cow closely for signs of illness and treat any symptoms that occur.
- All cattle that have RP should be examined by a veterinarian prior to their earliest service date.
- Regular weekly progesterone sampling can help determine if there has been any effect of the RP on the cow’s return to normal reproductive activity
Prevention
- There are no standard preventative regimes for RP as we do not understand
- Good dry cow management is the best way of preventing RP and reducing its effects. This will include supply of correct nutrients, particularly magnesium, and fat soluble vitamins, maximising dry matter intake, maintaining body condition score of around 3, and supplying a clean dry environment
- Most RP is not caused by a selenium deficiency. Most studies which have shown a response to selenium supplementation have reduced the rate of RP from 30+% to around 10% and no further. Selenium should only be supplemented if the cattle can be shown to be selenium deficient as over-supplementation can cause RP.