Body condition score (how fat or thin a cow is) is an important measure of animal welfare, and her health, particularly in relation to calving weight. In New Zealand the range is from 1 (emaciated) to 10 (grossly fat).
The ideal BCS at calving time is 5.0 for mixed age cows, and 5.5 for first and second calvers. We aim to have no more than 15% above or below these targets.
The cows at greatest risk of poor reproductive performance are the first and second calvers. We know that within a herd there is always going to be a range of BCS, as each animal will have a slightly different metabolism, intake, milk production etc. The challenge is to get the spread in BCS at calving as small as possible around the targets.
Once a cow calves, she requires a good deal of energy for lactation, which results in loss of body condition as she mobilises stored fat to make milk. This needs to be rectified by the end of her lactation so she is fit to calve next season.
All our cows receive a body condition score from a certified assessor at Planned Start of Calving (PSC), Planned Start of Mating (PSM) and then in November, February/March and May/June. Any cow identified at <4.0 BCS will be drafted out for a health assessment and will be preferentially fed or have her milking frequency reduced until she returns to a healthy BCS.
In 2020 cows calved at average BCS 5.7 (higher than target), and lost a lot of body condition in early lactation and during mating, with high milk production and subsequent BCS loss through to the end of October.
Using the DairyNZ BCS dry off calculator, cows are dried off based on their calving date and BCS to achieve targets at calving. Cows returned to BCS 5.0 by mid-June 2021.
In 2021, cows calved at an average of 5.0, with heifers reaching 5.5 and second calvers under target at 4.9. By PSM cows had reached an average of 4.6 BCS with heifers at 4.8.