Dairying comes under scientists scrutiny

Cows can eat the bulk of their daily intake in less than four hours, so why allow them to graze all day? This was among questions attendees to the Large Herds NZ 2009 Conference are pondering in the face of new science and reported in the Ashburton Guardian. Six young scientists presented the latest scientific information in their fields to delegates at the Ashburton Trust Event Centre as they vied for votes to win the inaugural Young Dairy Scientists Communication Award. Dr Pablo Gregorini,  spoke of his research into cow eating strategies. Cows grazing all day can create stress on pastures and waterways, particularly in environmentally sensitive areas, and increase nitrate leaching. He found in his research that cows grazing eight hours per day had a higher pasture intake than cows on 24 hours of grazing excluding milking time. Fine-tuning of daily grazing management could help farmers utilise nutrients supplied by pasture, as pasture had the highest nutritive value at dusk. Dr Kirsty McLeod, found 8-hour grazing compared to 24 hours reduced urinations on pasture by 41%. However it also reduced milk production, but feed supplementation could overcome this. Dr Mairi Stewart discussed animal welfare and has been developing a non-invasive technique for measuring stress and pain in cattle. It is a hand-held infrared camera, which measures radiated heat. Dr Jenny Weston of Dairy Systems presented her research into Neospora, the most commonly diagnosed cause of abortion in cattle in New Zealand. "Not keeping infected heifer replacement calves means that you will more quickly remove infected animals from your herd." Dr Jane Kay of DairyNZ discussed the real cost of a feed deficit. She said farmers needed to make informed management decisions about supplementary feeding. Andrew Weir of Eltham District Vet Services studied Bovine Viral Diarrhoea for doctoral research. The cost of the virus in New Zealand dairy herds was $75.29 per infected cow. This was only part of the total cost but was enough on its own to justify taking action in many herds.