An alternative wintering system for Southland: a comparison of wintering cows outside, on brassica crops versus inside, in a free stall barn in Southland, New Zealand : a dissertation submitted in partial fulfillment of the requirements for the degree of Master of Professional Studies at Lincoln University

Abstract

In New Zealand, dairy cows generally calve in the spring and produce milk through spring, summer and autumn. This is arranged this way to ensure that there is ample good quality grass available when the cows require it most; in early lactation. In the winter most farmers dry all their cows off to let them gain strength and condition in anticipation of the next calving and lactation. The feeding and tending of the cows during the winter period is generally called “wintering” Cows in the Southern parts of New Zealand are mainly wintered on brassica crops. This system has been inherited from the few dairy farmers that were there before the dairy influx in the nineties. Typically cows were farmed at 2.5 cows per hectare (“one cow to the acre”) and the cows were wintered on brassica crops on the milking platform (home farm). Fifteen to twenty percent of the milking platform was sown out in kale or Swedes and new pasture was sown afterwards. The soil had enough time to restore under pasture and this system worked reasonably well. It did not take long for the newly imported farmers to work out the opportunity cost of having part of the milking platform out of the grazing round for winter crops. Wintering the cows off the milking platform and increasing the stocking rate to about three cows to the hectare on the home block was considered to be a better option. Cows were sent off the milking platform during winter to a runoff. The crop rotation on such a runoff can be as intense as fifty per cent of the land in brassica’s at any given time. Most of these runoffs have previously been used for sheep farming with nearly the whole farm in grass. During the first crop rotation the whole farm can be introduced to brassica crops before the negative effects of this practice are noticed. A common practice is to plough up enough area for winter feed, use the ground for wintering for two years, put the paddocks back into grass and plough up the next lot. This first crop rotation can take up to eight or ten years, but at some stage the first cropping round will run out and paddocks that have had brassica crops in them before will have to be used again. This is when the negative effects are felt in regard to soil structure damage and weed infestation. The viability and sustainability of this system is now in question. This report describes an investigation into the physical, environmental, animal health/ welfare and financial implications of an alternative to this system.