Increasing on-farm grazing potential by up to 3500 extra sheep grazing days is one of the many benefits of introducing crop grazing into pasture-based systems, according to former CSIRO researcher Dr Hugh Dove.
He said the practice could boost on-farm winter sheep carrying capacity from 800 extra sheep grazing days for a single crop to 3500 if cereals, canola and pasture were grazed in sequence.
“While grazing of the crop is the major benefit, as much as 40 per cent of the extra grazing which occurs in the pasture-crop system arises from extra pasture which is grown when livestock are off-pasture, grazing the crop,” Dr Dove said.
Dr Dove is a keynote speaker at Animal Production 2016, an international biennial conference hosted by the Australian Society of Animal Production from July 4-7, 2016 in Adelaide, South Australia.
He said crop grazing provided an increased animal welfare benefit of additional nutrition during winter – proving particularly useful to producers who lambed down in autumn.
Best of all – grazing had little effect on crop yields – if correct grazing management was used and sheep were removed before crop stem elongation.
Dr Dove said on occasion, in past research trials, increases of up to 20 per cent in grain yields had been recorded.
“It sounds counter-intuitive but cereals such as wheat can produce a huge amount of biomass if sown early, so if they are grazed this can significantly reduce the amount of biomass,” Dr Dove said.
“This helps reduce the plant’s use of soil water in winter, meaning it has access to it in spring, during the critical grain-filling period.”
Dr Dove said although there was a recent resurgence in the popularity of grazing crops, the idea of grazing crops was “nothing new”.
“It’s something that has been done for almost a century, but in the post-world war years varieties of dwarf wheat were developed which were excellent for grain but which, because they rapidly came into head, could be very difficult to graze without major loss of grain yield,” he said.
“Grazing crops is a management tool that can have many benefits, particularly in helping improve animal welfare during a traditional feed gap, and with no detriment to the crop as long as animals are put on and taken off at the right time.
“On wheat they need to be removed by growth stage 31, i.e. at the first hollow stem. The question of when to remove stock from the crop is actually more important than the stocking rate used for crop grazing.”
Dr Dove said that GRDC-funded studies near Canberra had shown that grazing canola could be done in a manner similar to wheat.
“It’s a very analogous situation to wheat conceptually in terms of management and outcomes,” he said.
He said supplementation with magnesium or sodium was important for livestock performance when grazing wheat.
“Studies have shown that it might cost 1 cent a day to supplement sheep with a mix of magnesium oxide and salt, but supplementation can result in an increase in liveweight gain valued at 20c/day,” he said.
“It’s very important to keep an eye on mineral nutrition, which differs depending on the crop.”
Dr Dove will present as the McClymont Lecturer at the conference, alongside international researchers such as Professor Temple Grandin, an award-winning animal behaviour expert from the United States.
Conference sponsors include the University of Adelaide, Primary Industries and Regions SA, Elanco Animal Health, Australian Pork Limited, Gribbles Veterinary, Steggles, Dairy Australia and JBS Australia – Southern.
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