‘Only a matter of time’ before growth hormone comes

Press, 2 November 1984, Page 24

‘Only a matter of time’ before growth hormone comes

Growth hormone will be commercially available in New Zealand within a few years, bringing spectacular increases in animal production and a period when farmers will have to adjust their management. Dr Stuart McCutcheon, a lecturer in animal science at Massey University, returned to New Zealand with this view after spending two years working with the hormone in the United States. The research was conducted at Cornell University, New York, as part of a Harkness Fellowship programme. According to Dr McCutcheon, there is. renewed interest in the commercial use of growth hormone as a result of a research breakthrough that occurred in the late 19705. United States chemical companies are now making major investments to develop the product, and research programmes at American universities — particularly Cornell — have benefited substantially. For 40 years, growth hormone has been known to increase milk production and growth rates in farm species, but until recently, supplies were limited to the amounts which could be extracted from the pituitary glands of slaughtered animals. Recombinant-D.N.A. technology changed everything. Large quantities of growth hormone can now be produced making it a commer-

cial proposition for United States companies. Dr McCutcheon maintains it is only a matter of time before recombinant hormone will be approved for use in agricultural systems in the United States and it will arrive in New Zealand soon after.

“When this happens, dairy cows receiving the hormone will increase milk production by 10 to 30 per cent over a whole lactation, and young cattle will increase average daily gain by 10 to 20 per cent with a better protein to fat ratio in the carcase.”

He added that, while most of the research had been carried out on growing and lactating cattle, dramatic improvements in sheep production were also possible.

“Growth hormone could improve growth rates and carcase composition in lambs, and similarly, hormone treatment could be used to improve wool production,” he said. “But the dairy fanner will probably be the first user here in New Zealand and the first to see the way it will affect farming systems.

“The effects of production will be the same as the effects of genetic improvement. Cows will produce more milk, eat more to compensate, and. mobilise more reserves in early lactation. However, it will be like many years of genetic improvement occurring overnight and farmers have to be ready to adjust their management. “Much greater demands on feed will mean dairy fanners have to reduce stocking rate, a management decision that will not come naturally,” he said. And calving dates may also have to be altered because research suggests that the hormone could shift the time when peak intake occurs.

Dr McCutcheon is convinced, however, that if appropriate management steps are taken when the hormone is introduced, New Zealand agriculture is in for a period of dramatic increases in production.