Good autumn nutrition king

If the stock condition is going backwards it is often because of poor nutrition Sarah Sutherland writes.

Autumn ill-thrift in finishing cattle is a recognised condition in New Zealand.

It presents as R1 or R2 cattle that were previously growing well having reduced or negative growth rates for three to eight weeks in autumn despite good feeding levels.

The condition often but not always presents with scouring and poor body condition. The condition can also occur in growing lambs.

There are several factors which may be involved, and not all will be present on each farm. The most common reason is that feed quality or quantity may be lower than you think. Other causes are parasites, trace element deficiencies, diseases especially BVD, Yersiniosis, adenovirus, facial eczema, or toxic fungi in the grass. In some cases a cause cannot be found despite a comprehensive work-up, which means there may be something out there which has not yet been identified.

The overwhelming cause of ill-thrift is poor nutrition. Steers weighing 500kg with a growth rate of 1kg/day require 127 MJME/ day (range 109-135). Normally protein is not limited in autumn pastures. Autumn pasture has a lower efficiency of energy use than spring pasture even though it has high digestibility and high protein. This is because the pattern of volatile fatty acids (VFAs) released from the rumen bacteria is different, and there is an increased energy demand to convert excess protein to urea.

Very low fibre, high soluble carbohydrate diets can lead to scouring and poor growth. The low fibre diet doesn’t stimulate chewing and rumination, which means the animal absorbs less saliva. Cattle saliva is necessary to prevent rumen pH from dropping. Rapid fermentation of soluble carbohydrates also reduces the pH of the rumen.

Rumen bacteria killed

Low rumen pH (acidosis) kills off rumen bacteria, further decreasing the energy released and changing the volatile fatty acid profile. Intestinal contents that are less well digested suck water into the gut from the digestive tract, causing diarrhoea. Fast growing spring and autumn pastures in NZ are typically low in non-digestible fibre (NDF) and good growth rates are still achieved in many cases. If this is a component of the problem, adding fibre to the diet by supplying hay or straw will stop diarrhoea, and improve the efficiency of digestion.

Parasites can contribute to autumn ill-thrift. Worm egg counts are less valuable in cattle than in lambs, and parasitism can be a factor even with low worm egg counts in animals more than 15 months. However, high worm egg counts mean that a drench is needed. Cooperia is a common worm in young cattle in autumn. Often the most sensitive indirect measure of parasitism in cattle is lower than expected growth rates.

If your farm does not have a bovine viral diarrhoea virus (BVD) control programme or there has been a potential biosecurity breakdown, may be the cause. Cattle infected at this age have a period of about one month of poor growth rate or weight loss and scouring. You may or may not also see lame animals, or sometimes animals that are drooling or have a discharge from the nose.

Animals not born with BVD will recover in about four weeks and then usually regain full productivity after recovery. A blood test for antibodies will tell us whether BVD is active in the herd. If BVD might be an issue in your herd, we strongly recommend you book a BVD consultation with your vet. They will be able to help you make a BVD control programme for your herd. Vaccination may not be cost effective in a trading mob, but identifying and getting rid of the permanently infected (PI) animal may be.

Yersiniosis is a bacterial disease that can affect weaner cattle in autumn after a period of cold, wet weather or after periods of stress including nutritional stress such as after an autumn drought. It causes fever, scouring, weight loss and occasionally some deaths.

Diagnosis is by culture of the bacteria from faeces or from post mortem samples. Sick animals can be treated. Adenovirus can also cause scouring, weight loss and death in younger cattle. This disease also seems to occur more commonly after a period of poor nutrition.

Wairarapa cattle lack trace elements

Trace element deficiencies are common in cattle in the Wairarapa. The two most common deficiencies seen are copper and selenium. In young cattle either of these deficiencies will be displayed as poor growth rates.

Trace elements are required as components of enzyme pathways. When they are absent or only available in low amounts, the pathways are slowed, causing poor growth rates. Blood samples or liver samples will tell us whether supplementation will improve growth rates in your animals. Your vet can then advise which products will achieve this.

Research has implicated fungi and endophytes as part of the autumn ill-thrift syndrome, however we don’t know enough about these to make recommendations for their control. Facial eczema can cause reduced growth rate before you see visible lesions (reddened, crusty, peeling skin). Some years and some paddocks are more likely to grow the fungi that cause facial eczema.

Grass can be tested for spore levels to determine whether facial eczema is likely to occur. Facial eczema is a problem in some years and not others in the Wairarapa. Other fungi or endophytes may cause problems but we do not yet have a way to test for these.

In summary, autumn ill-thrift is a common syndrome in beef cattle in NZ. There are a number of different factors that may be involved. This means it is always worth talking to us about a mob you are concerned about. The most common reason is poor nutrition. Remember that in autumn feed availability and quality may not be as good as it looks.

• Sara Sutherland is a veterinarian with Veterinary Services Wairarapa.