Young, lush pasture ferments easily and produces large amounts of gas in the rumen.
Normally this gas is belched up however, when the pasture has a high legume content (clover, medics or lucerne), natural foaming agents trap the gas in small bubbles which cannot be belched out.
Pressure builds up in the rumen causing an obvious swelling on the left-hand side and pressing on the diaphragm and lungs as well as blood vessels. Animals get stressed, breathe rapidly and stagger before they die.
Treatment is urgent. Commercial anti-bloat preparations or vegetable oil (250—500 ml) or paraffin oil (100-200ml) can be effective, perhaps given by stomach tube to let the gas out. In severe cases, where animals are down and struggling to breathe, releasing gas with a wide-bore trocar and cannula (or even a clean knife blade) in the upper left flank where swelling is greatest can save an animal’s life.
Prevention is better. Limit pasture intake by turning livestock into new paddocks late in the day, filling animals with high fibre food first, strip–grazing and allowing 10 -14 days for rumen microbes to modify to this rich diet. Other mechanisms include supplying bloat oil in the water supply, alcohol ethyloxalate and molasses in a roller drum, anti-bloat licks or blocks.
Lush pasture also stimulates rapid growth of gut microbes. Among these are the Clostridia, some of which cause pulpy kidney. There are rarely any warning signs before you find dead animals so make certain that all livestock are recently (within the last 2 months) vaccinated with a 5-in-1 at the very least.
A pulpy kidney booster is needed every three months and takes several days to stimulate immunity after giving the vaccine. Please be warned – every year we see countless animals dying of Clostridia because producers think an annual booster is good enough. It is not.
Barber’s Pole worms are blood-suckers and don’t cause diarrhoea or weight loss as first signs. Recent rainfall and warm weather ensures worm eggs on pasture rapidly develop into larvae and re-infect sheep. They cause weak sheep with pale gums and sudden death if you aren’t aware of what’s happening.
Regular worm egg counts to determine worm burden will help to avoid a crash. Ensure drenches used are effective and seek advice about taking an integrated approach to worm management on your property.
Prevent Barber’s Pole worm with Barbervax (but you must dose regularly) or treat with an effective drench – be aware there is a lot of drench resistance on Northern Tablelands.