Farm Ireland

Tuesday 16 January 2018

Identify risk status of your herd ahead of vital dry-cow period

Dr Dan Ryan

As the month of October ends, we still have very mild weather, excellent grass growth rates and grazing conditions.

Milk prices are excellent, with some farmers getting close to 50c/l for milk with high solids. The temptation among some farmers is to continue to supply milk even with a superlevy imminent.

Caution needs to be exercised on animal health at this time of year. Bulk milk testing has recorded a high incidence of liver fluke, stomach fluke, stomach worms and IBR in unvaccinated herds. This is supported by the fact that approximately 30pc of cows scanned by CowsDNA are below the target body condition score for this stage of the production cycle.

Poor body condition score at this time of year is always associated with inadequate dry matter intakes, lameness or clinical symptoms of disease. Scanning cows now will reveal many empty cows, which are a surprise to farmers.

Further investigation will reveal the causes as loss of multiple pregnancies, neospora associated with mummified pregnancies, high infection rate for liver or stomach fluke, lung worms, stomach worms and IBR.

The clinical symptoms for many of these diseases only becomes evident at this time of year. It is worth noting that a clinical infection of stomach worms can consume in excess of 1kg of concentrates every day.

Prevention of these problems is far more cost effective than treatment because these diseases have far reaching consequences.

Eighty per cent of herd health problems arise during transition from the dry cow period through early lactation. You need to ensure your cows are fit when they are dried off and maintain this status until they calve down. The danger is that cows will not be fit for the dry cow period with a consequent immune system depression during the transition period.

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Diseases such as liver fluke, stomach fluke, lung worm and stomach worms will cause immune system depression. The response to a vaccination programme against an outbreak of IBR will be poor if the primary cause of ill health is not addressed.

Some farmers will refrain from treatment of cows with infestations of liver and stomach fluke until cows are dried off because they consider that the milk withdrawal period required to be too costly. However, the long term cost implications are far greater.

BVD was the disease of primary concern in the past. The Animal Health Ireland (AHI) eradication programme has shown that 98pc of 1.9 million calved being diagnosed negative to BVD in 2013.

However only 62pc of persistently infected (PI) calves have been culled from herds, with most of these being retained on suckler herds. The Department of Agriculture recently introduced financial incentives to remove PI calves from beef herds.

IBR is now the disease of primary concern to dairy farmers. Currently, 75pc of dairy herds contain cows exposed to IBR virus. IBR can be spread by close contact between animals, either as airborne or through semen as a venereal disease. IBR symptoms include sudden milk drop, elevated temperatures, poor pregnancy rates and abortion. IBR outbreaks occur when cows are stressed. The infected cows, described as latent carriers, shed the virus when stressed.

Consistent vaccination programmes make it less likely that a latent carrier will re-activate and shed the virus. Vaccination will also reduce the likelihood of ill health in susceptible animals following exposure. However the response to vaccination programmes will be limited if the immune system is depressed because of lameness, liver or stomach fluke and stomach worms.

In conclusion, identify the disease risk status in your herd now and take action in consultation with your vet, to have fit cows for the transition period.

Dr Dan Ryan is a cow fertility expert and can be contacted at

Irish Independent