Agri Kultuur December / Desember 2015 | Page 26

ly lactation commonly known as cows milking off their backs. Higher genetic merit cows have higher peak milk yields and therefore a larger negative energy balance during early lactation. It is for this reason that cows should be in good condition when calving down preventing them using all their body reserves at peak production as this could lead to poor reproductive performance or metabolic disorders. (a) b) Figure 1. The change in (a) live weight and (b) body condition score over the lactation period for Holstein cows in different lactations based on monthly recordings The body condition of cows should be improved during the late lactation stage as the conversion of feed energy to fatty reserves in the body is more efficient in the late lactation stage in comparison to the dry period, i.e. 65% vs. 48%. This means that cows in a poor condition should receive more concentrates per day or a concentrate containing higher levels of grain or fat. The body condition of cows should be about 3.0 to 3.5 (from a possible 5.0). Cows being dried off at a condition score higher than 3.5 should be fed a smaller amount of concentrates per day during the dry period to prevent them for becoming overfat. Anecdotal data in KwaZulu -Natal showed that a one condition score change resulted in a live weight change of about 45 kg. However, differences were found between first lactation cows and older cows. Some cows may lose up to 90 kg in live weight in early lactation while each kg live weight loss may account for 5-6 kg of milk. It is for this reason that cows should be in a good condition when they calve down. Condition scoring technique Presently there are a number of methods to determine the amount of fat reserves on the body of dairy cattle. It usually consists of an arbitrary scale in which the amount of fatty reserves underneath the skin at the tail head and loin area is estimated. The most common system being used in South Africa was developed at the British National Institute for Dairying at Reading in the early 1970s. For each score a specific definition for the tail head and loin area is provided and scoring should be done by