The change to much wetter weather has resulted in a lot of cattle being housed in the past week. This wet, mild weather is not the best condition for housing cattle, especially weanlings.

When a shed is filled with cattle in the mild, moist atmosphere that we often get at this time of the year, conditions favour the spread of respiratory diseases. On most farms there should still be enough grass to keep the weanlings outdoors where they will be healthier, at least until we get cooler weather.

Parasite control

Internal parasites such as stomach worms, hoose and liver fluke are diseases of the grazing animal. Stock kept indoors all the time cannot pick up these infections. Therefore, the removal of parasites from cattle at the time of housing is an effective control measure that leaves them free of these parasitic diseases while they are indoors.

Infection carries over from one season to another in two ways: (i) as over-wintered larvae on pasture and (ii) within infected animals. Dosing at housing should rid stock of parasites, thus removing the negative effects of infection on performance and preventing the carry-over to the following grazing season.

At this time of year it is possible for stomach worm larvae to alter their pattern of development within the digestive tract and become arrested fourth stage larvae, often referred to as type II stomach worms. These can lodge in the gut wall over the winter and if large numbers are present they can cause late winter or spring scours. The severity of the spring scour is usually associated with animals under some stress due to under-feeding, other infections, over-crowding or pregnancy. To control type II stomach worms it is necessary to use drugs that are effective against this type of infection.

The white drenches and the Avermectin injectables and pour-ons are effective against type II stomach worms, but check with your veterinary supplier when purchasing drugs for dosing at housing.

Risk animals

Animals differ in their ability to resist hoose and stomach worms. Resistance increases as the animals get older. Young calves, when put to grass, have no resistance but can build up immunity quickly with low to moderate exposure. At this time of the year, late-born calves and those subjected to stress will be the most at risk. It is advisable to dose all calves and weanlings coming off their first season at grass with a drug that is effective against type II stomach worms. Young stores (spring-born 2008) will have developed a reasonable level of resistance, but in many cases these could benefit from a dose at housing, although the performance and economic response is not as clear-cut as with the younger animals. It depends on the level of challenge prior to housing and the immune status of the cattle. In general, older cattle (over two years, beef animals and suckler cows) have adequate resistance and do not need dosing if well fed and not under abnormal stress.

Young bulls at the end of their first breeding season are likely to benefit from a worm dose at this time. In-calf heifers may also benefit as sometimes the effect of pregnancy and milk and growth demands after calving will lower their immunity. This leads to scouring after calving. Even heifers after their first lactation could benefit from worming.

Fluke

The late spell of dry weather this autumn is unlikely to have reduced the risk of fluke disease, so fluke is expected to be a problem following the wet summer.

Unlike hoose and stomach worms, immunity to fluke infection is poor and therefore all stock exposed to infection require treatment at or after housing.

It is wise to get the advice of your vet if you are in an area where fluke disease is common. Local veterinary practitioners will know the extent of the disease in the locality and advise on treatment strategies.

Weanlings may need a dose now if they will remain at grass for some weeks and again after housing. Older cattle, including cows, should be dosed from one-to-six weeks after housing depending on the drug used. For example, Fasinex can be given from a week after housing and products containing Rafoxanide (Flukex, Rafazole, Ridafluke) and Nitroxymil (Trodax) from five to six weeks after housing.

Out-wintered stock in high-risk areas should be treated immediately (if not already treated) and repeat the treatment in six-to-eight weeks. These out-wintered stock would need another dose in February or March where they have access to grazing (winterage) in high-risk areas.

- Liam Fitzgerald

Irish Independent