Minimising calving difficulties - During pregnancy

Body condition score (BCS) at calving is closely related to how easily a cow will calve and how quickly cows start cycling again after they have given birth.

In general, very fat or very thin cows are at greater risk of difficulties around calving. Cows that are too fat in late pregnancy are likely to have problems because of the deposition of fat that narrows the birth canal. Thin cows have fewer body reserves and are more prone to metabolic diseases. They also produce less, poorer quality colostrum, which can result in weak calves.

It is important to record and monitor body condition and look out for any cows that unexpectedly lose or fail to gain condition because this could indicate an underlying health problem. Consult the vet about investigating cows with such issues. 

Managing feeding throughout the year can help to optimise body condition at each stage of the production cycle.

Body condition tends to vary with feed supply throughout the year, but it is best to avoid extreme and rapid changes in BCS. In particular, cows should not fall below a BCS of 2.5. If suckler cows are too thin, weaning the calves earlier than usual will enable the cow to regain body condition.

At winter housing, cows should be assessed and grouped according to their BCS, with thin or very fat cows being rationed accordingly. Rations should be developed so that all cows are on a target BCS of 2.5–3.0 six weeks before calving. Forage should be analysed and a ration offered that is appropriate to the condition of each group. 

Instead, feed to requirements, aiming for a minimum of 9% crude protein in the dry matter for mature dry cows. This will ensure that the cow is strong for calving and will produce sufficient, good quality colostrum for her calf.

Adjusting the ration can help prevent milk fever (hypocalcaemia) and staggers (hypomagnesaemia). Feeding an appropriate dry cow mineral during the latter stages of pregnancy will help to reduce the incidence of metabolic diseases and ensure adequate minerals are passed onto the calf before birth.

Youngstock and finishing minerals are not appropriate for dry cows because they are usually high in calcium and low in magnesium.

It is important to know what the mineral status is, both of the land and the animals. Cattle require many minerals during pregnancy and there are some complex interactions between them.

Take forage samples and blood samples for analysis and discuss the results with the vet or nutritionist. It may be necessary to supplement the diet with mineral boluses, injections or drenches, or to provide supplements via the ration. Common minerals that can affect fertility, calving, calf health and growth are molybdenum, iron, copper, selenium, vitamin E, cobalt and iodine. Supplementation through the water and via buckets, while popular, can often result in uneven mineral supply to the group.

As well as essential nutrients, the calf receives antibodies (immunity) from its mother through colostrum. It is important that the dam is up to date with her vaccinations and is in good health.

Colostrum quality is vital to give the calf the best possible start. If the calf does not receive enough good quality colostrum in the first few hours of life, immunity will not be passed on from the mother and her offspring will be susceptible to disease.

Herd vaccination policy should be part of the herd health plan and discussed with the vet.

Diseases such as Bovine Viral Diarrhoea (BVD) and Salmonella can have particularly severe impacts on newborn calf health and should be controlled as part of the herd’s health plan.

It is important to be prepared before calving begins. Suitable clean and dry shelter should be ready and available, as well as handling facilities and some basic equipment, for example:

• Clean calving ropes
• Long gloves
• Ear tags and applicator
• Tincture of iodine for dipping calf navels
• Calf-feeding bottles
• A calving aid 
• Calving lubricant
• Clean needles and syringes and some basic medicines – consult the vet about what is needed
• Disinfectant
• Stomach tube
• Torch
• Frozen colostrum

The information on these pages was compiled by Katie Thorley, AHDB Beef & Lamb and David Black, Paragon Veterinary Group and reviewed by Dr Alexander Corbishley, University of Edinburgh.