Overgrazing risk due to 'green drought'

A ‘green drought’ is currently being experienced in parts of the North Coast, bringing new risks to livestock. North Coast Local Land Services is warning producers to consider how to manage pastures and feed for dry times, even with the recent rain.

Brendan O’Brien, Senior Land Services Officer with North Coast Local Land Services, said “Just because it has rained it does not mean the dry times are over, summer is only just around the corner.

“After rain, it may be tempting to stop feeding livestock or cancel the hay on order, however, by ceasing feeding too soon, or grazing too soon, paddock recovery will take longer.

“The longer you can spell a paddock after rain, the quicker it will recover so we’re encouraging farmers to wait for sufficient pasture height and density.”

Green pick is ‘snack food not a meal.’ Allowing livestock to graze on green pick before it translates into a useful quantity of food is ‘easier now and harder later’ and is ‘short-term thinking.’

Providing enough quality hay or silage to livestock to meet livestock nutritional needs will reduce their need to chase the green pick but closing the gate is just as important.

Stock are best fed in a smaller paddock for locking up big paddocks to be effective, where they can’t chase the green pick.

While ‘green pick’ is a great sign of pasture growth and a reduced reliance on supplementary feed, new green growth also has a water content of up to 90%, making it impossible for animals to eat enough to satisfy their nutritional needs if they do not also have access to other types of feed.

It can take between 3 – 8 weeks before pastures offer a useful quantity of feed, with growth depending on the species of pasture and the height and density of these pastures before the rain event. Grazing pastures with a high water content (70-90% water) and short height (30-90mm) means livestock will expend more energy grazing for many hours but can also set pasture recovery back significantly.

Annual species such as ryegrass recognise the growing temperatures and are ready to run to seed or finish their growth period for the year before summer. Perennial grass species such as Setaria, Rhodes grass, Kikuyu or Couch are sub-tropical and are gearing up for a growth period, if there is continuing soil moisture to drive this.

“Producers should continue to provide supplementary feed for livestock until pastures mature and the water content drops,” Brendan said.

A good rule of thumb before grazing is that pastures should be at a starting point of 10cm height or over, providing at least 1200kg Green DM/Ha (Green Dry matter per Hectare). Livestock are best fed in smaller paddocks where they can’t chase green pick while those paddocks recover. Another strategy can be to slow down the paddock rotations, giving recovering pastures longer to grow while producers supplementary feed.

The Drought and Supplementary Feed Calculator can be a useful tool to assist in decision making around feeding livestock.

The North Coast Local Land Services District Veterinarian team have also provided advice on the impact of a sudden change of feed which can also result in pulpy kidney.

Pulpy kidney is a livestock disease caused by the overgrowth of clostridial bacteria in the gut which can occur with changes in feed, particularly when feed quality improves.

Animals being supplemented with heavy grain feeding or moving onto fresh green pasture are at high risk of the disease, which often manifests in young, fast-growing livestock without a full vaccination history. Pulpy kidney is fast acting and there are often no signs of sickness in livestock before death.

Ian Poe, District Veterinarian with North Coast Local Land Services, recommends a vaccination program of two doses of 5-in-1, dosed 4-6 weeks apart initially followed by an annual booster to achieve protection against pulpy kidney.

“More frequent boosters may be required in high-risk conditions like that we are currently experiencing, he said. “It is also important to provide pregnant or lactating livestock with a mineral lick as animals are more susceptible to metabolic diseases such as pregnancy toxaemia, grass tetany and milk fever during these conditions,” Ian said.

For more information about livestock health, contact your Local Land Services District Vet or Livestock Officer on 1300 795 299.

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