快猫短视频

WHILE consumers and supermarkets remain wary of genetically modified food, a
team of researchers is suggesting feeding cattle GM fodder designed to keep them
healthy.

Every year, cattle farmers in north America lose billions of dollars when
their animals get 鈥渟hipping fever鈥�, a pneumonia-like illness often triggered by
the stress of being transported. But injecting conventional vaccines is
expensive, and also causes stress.

So Raymond Lee and his team at the University of Guelph in Canada are
developing an edible vaccine. They took the gene for leukotoxin, a major protein
in the bacterium Mannheimia haemolytica, which causes the disease,
stripped it of its toxic elements, and inserted the rest of the gene into the
genome of white clover, a favourite food for cattle.

As the researchers hoped, the modified clover made leukotoxin, and when they
injected the protein into rabbits the animals produced antibodies to it. 鈥淚t can
still produce an immune response,鈥� says Lee. The antibodies neutralised the
original toxin.

But a commercially available edible vaccine is still years away. Lee鈥檚 team
have yet to confirm whether their clover can prevent the disease in cattle and,
if so, how much is needed. 鈥淲e don鈥檛 know yet how much to feed them,鈥� admits
Lee. This winter the team will start giving the modified clover to cattle to
find out.

The researchers say the genetically modified fodder will not affect cows
differently from the inoculations they get now. 鈥淵ou鈥檙e still injecting bits of
bacterial protein,鈥� says Lee.

But Isabelle Meister of Greenpeace says the GM approach is still a worry.
鈥淲hat if non-target animals start eating it?鈥� she says. She also points out how
easily genetically modified Starlink corn slipped into the human diet.