Dairy replacement rearing: a comparison of an integrated management system using fodder beet and traditional rearing systems

Abstract

Heifer rearing systems in New Zealand were compared in a theoretical study on weight and financial costs. The systems compared were restricted fodder beet, ad libitum fodder beet, contract grazing and on-platform pasture grazing. The aim was to identify the most cost effective rearing system to ensure heifers are grown to achieve or exceed target live weights at 15 and 22 months. Potential live weight gains were calculated through metabolisable energy in feed and daily animal intakes using reference feed standards. The pre-mating average daily weight gains were 0.59 kgLWT/day, 0.53 kgLWT/day and 0.49 kgLWT/day for the ad libitum fodder beet, restricted fodder beet and pasture grazing respectively. None of these diets meet mating live weight targets, however ad lib fodder beet was the closest at 1.8%. The weight gains between mating and calving on the ad libitum fodder beet diet and restricted fodder beet diet were 0.59 kgLWT/day and 0.53 kgLWT/day respectively, higher than 0.49 kgLWT/day seen in the pasture grazing systems. The ad libitum fodder beet diet live weights were undesired at 29.4% above target, however the other systems meet target weights. The most expensive rearing system was contract grazing at $2.85/kgLWT gained. This was followed by on-platform pasture grazing at $2.57/kgLWT gain. Fodder beet has the lowest cost of gain at $2.27/kgLWT gain. Cost analysis showed that live weight gain, not cost of crop, is the key driver of cost effective rearing systems. This research demonstrates that under careful management and feed restrictions fodder beet is a suitable and cost effective way to rear heifers in the New Zealand dairy industry.