Cowra Local Livestock Health Update

Grazing canola crops provide an exceptional feed base with high protein, but like almost all crops and pastures they come with a few livestock health risks.

In sheep, the most commonly diagnosed diseases are:

1. Photosensitisation: Tends to be seen in young lambs grazing immature plants (<6-8 weeks post germination). Results in puffy heads, droopy ears and eventually ‘earless lambs’.

2. Clostridial diseases (pulpy kidney, enteritis): Lush, rapidly digestible feed supports over growth in Clostridial bacteria. Ensure boosters are up to date and consider 3 monthly boosters if grazing lush feed like grazing crops.

3. Metabolic diseases in ewes: While canola is adequate in energy, calcium and magnesium it often takes a few days for ewes to start grazing the crop. This period of time off feed in heavily pregnant ewes or ewes with little lambs at foot can result in pregnancy toxaemia (‘preg tox’) and hypocalcaemia (‘milk fever’).

In cattle, the most commonly seen diseases are:

1. Bloat: Brassicas are a high risk bloat crop. Provide access to roughage and supplement with ionphores, such as monensin and lasalocid. These are added to numerous commercially available pre-mixed loose licks, which also contain salt, calcium and magnesium.

2. Nitrate Poisoning: Dull, cloudy weather can reduce photosynthesis in the plant, which in turn can allow the nitrates to accumulate. Consider removing stock from the crop during and for a week after these periods if possible, or alternatively increase the amount and quality of hay being fed out. Crops recently top-dressed with nitrogenous fertiliser, such as urea, are considered high risk. Avoid grazing any crop within 4 weeks of a nitrogen application.

As a general rule, never give hungry animals the chance to gorge themselves on a lush crop. Introduce stock gradually so that their rumen microflora have the chance to adjust to the high quality diet. A few hours per day initially (10am-2pm) for seven days is the most cautious approach. Once adjusted onto Brassica, don’t chop and change their feed base. While high in crude protein and energy, Brassica crops, like all grazing crops and lush pastures, are low in firbe content. Consider having hay available, particularly for pregnant and lactating animals, when first introducing stock to a paddock, and, during periods of bad weather.

And lastly, but certainly not least, keep an eye on them! Grazing any crop is not a set and forget system. Watch them closely and if you notice any issues contact your veterinary immediately for advice.

Most commonly diagnosed disease this month? Benign Footrot. Continued mild conditions with good pasture mass and sheep going onto crops has meant that the environment is ideal for the expression of benign strains of footrot. Footbathing with 20% zinc sulphate and 1-2% sodium lauryl sulphate, or Radicate, is highly effective and an important part of keeping benign strains in check during wetter seasons.

If you would like further information or to chat about any animal health issues, please feel free to contact your local District Veterinarian’s: Em Johnstone (0419 334 077) or Evie Duggan (0427 147 939).

• Topics:
• Agriculture / Farming