Seasonal Livestock Update - Summer Active Pastures
10 February 2015
Change in seasonal conditions may cause problems with Kikuyu, Setaria and other summer active pastures.
The recent change for the better in seasonal conditions in most areas is welcome but of course, some could do with a lot more rain. However, lush growth of Kikuyu and other summer growing grasses after a prolonged dry spell can lead to toxicity problems. Phil Kemsley, a District Veterinarian for North Coast Local Land Services said "This can be frustrating, as these grasses are normally considered quite safe."
Phil continued, "Where activities normally considered safe can change with a seasonal variation, the team of District Veterinarians at North Coast Local Land Services can help."
Several problems to watch for include:
Deaths from bloat on Kikuyu have been a recent problem in the Kyogle area. Pastures that are being rotationally grazed or strip grazed seem to be more bloat prone. This is unfortunate because these are otherwise sound grazing management practices. Prevention is by grazing bloaty pastures with caution, putting the cattle in later in the day rather than first thing in the morning. Bloat oil in water troughs, or if the cattle are supplementary fed, in feed also helps.
Pastures that are most prone are those which are lush following rain after a prolonged dry period, those that have been fertilized with Nitrogen, or which follow a legume crop, such as soya bean. Early mornings after a day or two of overcast weather can see high levels of Nitrate in grasses, which is converted to Nitrite in the rumen and lead to death very quickly. Cattle do become accustomed to Nitrate with time as the rumen flora adjusts. Again prevention is by putting the cattle in later in the day and not early morning, when Nitrate levels are their highest. The stem tends to have higher levels of Nitrate, so light grazing is safer.
This can be a problem on lush Setaria, particularly in cattle which have not grazed Setaria for some time. It is also seen on Kikuyu. Oxalate manifests in one of two ways. A milk fever (hypocalcaemia) syndrome when the Oxalate binds the Calcium in the blood. This is treated with Calcium injection. The other syndrome is sickness and death from kidney failure from the kidneys being damaged by the fine sharp Calcium Oxalate crystals. Unfortunately this is much more difficult to treat. As with Nitrate, rumen flora does adjust to Oxalate, so prevention is by introducing onto lush Setaria or Kikuyu gradually.
Whilst not common, devastating outbreaks with high mortalities have been seen on the North Coast. In the late summer and autumn a Fusarium fungus (not Kikuyu yellows) can infect the kikuyu stem and produce a toxin. This is seen on lush long Kikuyu, following a prolonged dry period. As with Nitrate, the stem contains more toxin, and problems occur when the kikuyu is grazed low with strip or crash grazing. Affected cattle appear bloated, but it is with fluid in the paunch rather than gas. They are uncertain in their gait and can exhibit an unusual behavior of sham drinking or grazing, in which they pretend to eat or drink, but do not swallow. There is little to be done to treat affected cattle. Prevention is similar to the other conditions, graze lightly. However outbreaks are very difficult to predict.
Your district veterinarian is a valuable resource for locally relevant, up-to-date, independent advice and information on biosecurity and animal health issues.
Livestock producers can access their district veterinarian to increase their livestock health and profitability or to address livestock biosecurity concerns. Contact your North Coast Local Land Services office to be put in touch with your district vet.
Photo Caption: Kikuyu
Media Contact: Phil
Kemsley, District Veterinarian
Telephone: 6623 3905, Mobile 0427 896 822