The South Island dairy lameness group project

Abstract

Lameness is an important issue wherever dairy production occurs. It is consistently placed after infertility and mastitis in the top three cow health issues for farmers both internationally and in New Zealand (NZ). It has been a commonly held view in the South Island (SI) industry that there is more lameness here than in the North Island (NI), and that the problem has been growing in recent years. There are strong opinions in the SI industry suggesting there are important local influences on lameness. This is often explained in reference to differences between the NI and SI climate, herds, and management. The current SI herd has a cluster of features linked to the recent history of dairying here. In the past 15 years there has been strong expansion of the NZ dairy industry into the SI, where cheaper land and the availability of extensive, dependable irrigation have enabled a sustained increase in the number of dairy farms and cows (Anonymous, 2006). Despite the obvious similarities of grass based dairying between the NI and SI, there are several observed differences. The average farm in the SI has a greater herd size and greater per cow and per hectare production, and this high production is particularly pronounced in some regions (eg. Canterbury). Over the period of expansion there has often been emphasis on increasing herd size, which can reduce options around culling of cows. Many SI farms are conversions and irrigation along with intensive, recent pasture refurbishment are common features. Pasture management is often a top tier priority, and very intensive systems, to increase utilisation and maintain high quality (high energy, low fibre) across the season are commonplace. In addition, the long daylight hours and cooler nights are thought to promote higher sugar content in the pastures. Against that background, the origins of the most common and longstanding explanations within the SI industry for high lameness - particularly the role of nutrition - can be better understood. In brief summary, the popular idea of the influence of nutrition, the high energy and low fibre pastures are thought to induce rumen dysfunction resulting in secondary weakness in the hooves.