Heat stress in dairy cattle and other livestock under southern African conditions. I. Temperature-humidity index mean values during the four main seasons

Abstract

The Livestock Weather Safety Index (LWSI) indicates that in large areas of South Africa and South West Africa / Namibia and for prolonged periods of the year warm conditions are causing heat stress in food producing animals, especially dairy cattle, thereby hampering their performance. South Africa and South West Africa / Namibia have been mapped according to a modified LWSI, which includes the critical "temperature-humidity index" value for milk production. The importance of heat stress in dairy cattle is discussed relative to such areas.