Pasture supply remains the most common limitation to achieving higher milk production for New Zealand dairy farms. The seasonal nature of pasture growth results in feed deficits at critical times of the year. Long lactation lengths are difficult to achieve in all grass systems, especially at higher stocking rates required to maximise pasture utilization. Filling the feed deficit with maize silage - a low cost, high quality supplementary feed - can extend lactation length, increase production per cow and per hectare and most importantly, increase farm profitability.
Short lactation lengths are costly - the herd needs feeding regardless of whether it is producing milk or not. If pasture supply is limiting, feeding maize silage to extend lactation length can significantly increase economic farm surplus. As a result, dairy farmers throughout the country are using maize silage to put extra milk in the vat at the end of the season, while increasing cow condition.
Feed deficits at critical times of the year limit productivity. Without feed reserves, higher stocking rates can make early spring and summer feed deficits more severe. This leads to poor productive performance, early drying off, poor cow condition, extra cost and stressful farm management.
Maize can be used strategically to fill early spring and summer feed gaps. This enables farmers to take advantage of periods of strong pasture growth, while maize silage use reduces the risk of running out of feed during other times of the year. The resultant certainty of feed supply reduces seasonal changes in production, stabilising income and reducing farmers own stress levels.
Long post-calving rotation lengths are necessary to ensure the farm has enough pasture to meet the herd's requirements. Speeding up grazing rotation often results in a drop of pasture cover together with loss of cow condition and lower early season milk production. The use of maize silage during this period can overcome these potential problems. Furthermore, dairy research has confirmed that a herd well fed in early lactation will have fewer non-cycling cows.
Research results show that providing good quality maize silage will increase lactation length, while very high milk response rates of well over 100 grams of milk solids per kilogram of maize silage drymatter fed can be achieved.
There are so many variables when comparing and analysing growing and purchasing costs. The question regularly asked is "Should I grow on farm or buy in?" Growing on farm is becoming increasingly common. Depending on the crop's yield, it is possible to grow maize for between 12 cents [24 tonne/ha DM] and 17 cents [16 tonne/ha DM] in high fertility paddocks. Bought-in feed often costs significantly more, however, these costs are known well in advance and can be budgeted for.
Growing maize silage on farm allows the use of high fertility effluent treated paddocks. This enables the recycling of dairy shed effluent through the maize crop and provides the opportunity to introduce modern higher yielding grass species in the autumn. Feeding cows on maize silage also reduces the amount of nitrogen lost in urine patches. These are all encouraging reasons to grow maize, a plant that provides an outstanding feed source.