Most New Zealand deer graze on ryegrass and clover pasture, but some specialist pastures such as chicory are also used. Supplementary feeds in winter may include silage, hay, grain or forage crops. No hormones or growth stimulants are used in farming New Zealand deer.
Unlike most traditional livestock, deer have an extremely seasonal feed intake – high in spring and summer, less in winter. This is a reaction to day length. Deer from temperate or cold environments have developed this characteristic for survival reasons over thousands of years. Feeding standards which recognise the seasonal aspects of feed intake have been developed, and these are different for the each sex.
Matching deer’s nutritional requirements with the normal seasonal pattern of pasture production can be difficult. In late spring, pasture growth is well beyond the needs of deer, but in winter and summer there is often a feed deficit. In New Zealand deer have their calves in late spring or early summer, and their feed requirements during lactation are very high in summer – a time when many areas have hot, dry weather, not conducive to good pasture growth. Calving in early October (spring) would better match pasture growth to hind requirements, but day length strongly affects the reproductive cycle, so this is difficult to alter. In areas with dry summers, poor lactation (and depressed calf growth) are common unless the deer are fed supplements such as grain.
Stags are seasonal in their natural feed intake cycle. At the approach of the rut (breeding season) in autumn, they reduce their feed intake and concentrate on breeding. Even in the absence of hinds, feed intake is less in autumn. Stags can lose 30 kilograms and most of their body fat at this time. They enter the winter with little fat and are very vulnerable to cold weather. Stags need high-quality feed in winter – and in spring, when their antlers are growing. More mature, lower-quality pasture is adequate in summer.
Calves are born from mid-November until Christmas, and growth depends mainly on the hind’s milk production. The first half of lactation is at a time when pasture quality is high, and calf growth rates reflect this. Through January and February feed conditions vary between seasons and districts.
Young deer potentially grow more in spring and summer, and less in winter. They can be weaned before the rut, at three to four months of age, or in early winter after the rut. Pre-rut weaning is more traditional, as the weather is warmer and better feed is available. Deer in the wild are not usually weaned until after the rut, and their growth rate from March to August is higher than in farmed deer weaned before the rut. Young deer grow only slowly in winter regardless of feed, so there is little benefit in feeding high-quality rations. From mid-August, weaner appetite increases rapidly over six weeks. In this late winter period, particularly in the South Island, there is a good case for feeding high-quality supplements like grain.