Red deer should be calving earlier

Press, 12 September 1986, Page 21

Red deer should be calving earlier

New Zealand’s Red deer should be calving two months earlier than at present, according to a Ministry of Agriculture and Fisheries scientist, Dr Jimmie Suttie. December calving is an adaptation from the Northern Hemisphere, where Red deer originated. There, the middle of • summer is the only time that feed and climatic conditions allow calves to survive. The hormone melatonin is being used by Dr Suttle’s research group at Invermay Agricultural Centre, near Dunedin, to advance the Red deer breeding season. Mammals produce melatonin in greater amounts during periods of darkness than in periods of light. As nights become longer the amount of melatonin produced by Red deer increases causing hinds and stags to come into season during March or April. Dr Suttie’s research uses Australian melatonin capsules to ensure hinds ovulate six to eight weeks earlier than usual. Stags also roared in January instead of March. In New Zealand the peak pasture growth and mild weather of spring is a more appropriate time

to calve, Dr Suttie said. At that time deer feed requirements are normally low and farmers have to make silage or hay, or buy cattle, to keep surplus pasture down. Later in summer, hinds with calves need far more feed to provide milk and supplementary feed is often necessary in dry areas. Calves born in October could reach slaughter weights by the end of the summer, at eight or nine months of age, Dr Suttie said. Stags could be slaughtered before winter, avoiding the costs of winter feeding, and venison would go onto the British market at a time when little local meat is available. To establish the best way to administer the hormone one group of hinds and stags had the small capsules implanted while a second group had the hormone added to their feed. The capsules release the hormone at a constant level for 28 days. Capsules were implanted in November, 1985, and replaced each month until March, 1986. After treatment, other mating changes occurred, including growth of winter

coats and the loss of stag body weight. But the percentage of viable sperm produced by the stags is causing concern, Dr Suttie said. It may be the result of delays between semen tests and further work will be performed on that aspect as melatonin research continues.