Pregnancy scanning of spring calving herds is in full swing at the moment. Many farmers like to scan around this time as the age of the pregnancy can be gauged more accurately than later in the year.
ows served at the end of April are now just over four months in calf.
At this stage, the growing foetus is starting to move from being in the pelvis of the cow to down in her abdomen — something to consider if you were thinking of leaving scanning for another month or two when ageing will be less accurate.
Farmers, for the most part, are happy with results. If we consider how miserable the weather was in late April and most of May, it is a testament to both the cow and the farmer that there are some quite satisfactory conception rates to first service being seen.
The hard graft of heat detection, AI and bull management now seems all worthwhile when a good scan result is achieved, not to mention the extra meal fed during the bulling season. A lot of time, effort and considerable expense has gone into getting your herd of cows back in calf.
Now, for the rest of the year, we need to focus on taking every precaution necessary to keep these cows in calf. What I’m really talking about is preventing the causes of abortion in both our beef and dairy herds. There are a number of common causes of abortion, but thankfully, there are measures that can be taken to prevent them.
The first one that springs to mind is leptospirosis. Lepto is a bacteria that survives in stagnant water and wet soil. It can be passed directly from cow to cow and some cows can act as carriers. It can also be passed on in the urine or milk of infected cows. Along with abortion, it also causes general infertility and a drop in milk yield.
It is worth noting that lepto can also be picked up by people. We have all heard of Weil’s disease and I know that when I think of this disease, I immediately think of rats. However, farmers and vets alike have contracted the disease from the urine or foetal fluids of infected or aborting cows. Thankfully, prevention is easily attained by vaccination.
There are two lepto vaccines available in Ireland — Leptavoid H and Spirovac. Both require a primary course of two shots, four weeks apart. A booster is then given to all cows in the herd once yearly. Talk to your vet to discuss which vaccine to use and when to use it. This depends on a number of things including timing of other vaccinations, labour and facilities.
The next cause of abortion that springs to mind is salmonella. This is very pertinent to this time of year as most spring calving herds will vaccinate this month with Bovivac S, the only salmonella vaccine available in the country. This vaccine is given in a 5ml dose, under the skin.
The primary course is two shots, 14-21 days apart followed by a yearly booster. Salmonella is a nasty disease and I have witnessed first-hand some horrendous outbreaks in herds. An abortion caused by salmonella will usually result in a very smelly decomposing foetus and a very sick cow. The disease comes in other forms such as terminal dry gangrene in young calves.
This is an absolutely awful condition whereby the blood supply to the extremities becomes compromised, leading to a calf’s tail, ears and even its feet literally rotting off. A drop in milk yield, scour and joint infections are other forms of the disease. If the visible effects of the disease can’t convince you to vaccinate, then the economics of it will. It has been shown by researchers that an outbreak of salmonella can cost up to €112/cow.
This may seem like a high figure, but ask any farmer who has been through an outbreak and he/she won’t be long totting up the figures. Antibiotics, anti-inflammatories, fluid pumping sick animals for days, the loss of milk and sadly, the loss of some animals all add up. Put this figure beside the cost of the vaccine, which is available for south of €6 per animal and I know which one I’m choosing every day of the week.
Neospora is a cause of abortion that is a real “head melt” for any farmer that is trying to rid it from the herd. Once infected with this parasite, animals remain infected for life. An infected cow may calve normally for a few years and then abort sporadically. If an infected cow has a heifer calf, that calf will always be infected and will have a high risk of aborting as an adult.
Although dogs are the initial cause of the disease entering the herd, it has been shown that 90pc of infected cattle contract the disease from their mothers, whereas only 10pc contract it from dog faeces. Dogs become infected by eating the contaminated cleanings or aborted foetus infected with neospora. This is a disease that can gradually creep into a herd and be at a significant level before it becomes noticeable.
Unfortunately, there is no vaccine to prevent neospora, so other preventative measures need to be taken. If you have dogs on the farm or if people walk dogs on your farm, all faeces should be scooped up and disposed of. Neospora can survive for six months in infected dog faeces. Foxes, too, can be a source of neospora, so every attempt should be made to make any feed and feeding area as fox-proof as possible.
Foetuses and cleanings should be collected immediately and disposed of. Carriers of the disease should be identified by blood test and either culled or bred to a beef sire. A yearly screening test should be carried out to ensure all carriers are identified.
Any disease that causes a significant rise in temperature risks causing abortion. IBR immediately springs to mind, so its worth checking that your vaccination programme is up to date.
A less obvious one is mastitis. We have seen an increase in the incidence of cases of mastitis of late. A severe case of mastitis can make a cow quite sick and the developing foetus can often suffer as result.
It is always worth trying to find the cause of an abortion, particularly if it turns out to be contagious and needs preventative measures put in place. Take the foetus and placenta to the lab and get your vet to take a blood sample. If you don’t know the cause, you can’t find the solution.
Eamon O’Connell is a vet with Summerhill Vet Clinic, Nenagh, Co Tipperary
