Are your cows big enough?

Body condition scoring has many benefits, as Vetora veterinarian Faith Stevenson explains.

OPINION:

April is an excellent time to body condition score (BCS) your herd. Dry-off is quickly approaching for some, while it has already begun for others. Unless precautions are taken, cows will be losing condition. Body condition is a scale of “fatness”, where 1 is emaciated and 10 is obese. To score a cow, fat reserves on eight body parts are assessed: the long ribs, short ribs, backbone, pin bones, hips, rump, tail head and thighs.

Maintaining an adequate body condition score throughout the season has numerous benefits including increased milk solid production, increased reproductive efficiency, decreased risk of mastitis and uterine infections, and a decreased risk of metabolic diseases. Additionally, a cow’s BCS is one of the main drivers of the six-week incalf rate. A higher six-week in-calf rate means more days in milk, more milk production, and more money.

It is the individual cow in a herd that has an impact in terms of reduced milk production and poor reproduction performance. However, focus is most often put on the average condition score on the herd.

This is dangerous because even though the average may be “on target”, a large proportion of individual cows may be below the target BCS. Therefore, the preferred target is “no more than 15 per cent of the mature herd is less than BCS 5.0 at calving”. First and second calvers need to be slightly larger at BCS 5.5.

It is important to BCS your stock during summer and autumn. This allows individual groups of cows to be managed differently so that condition targets are met by calving. Scoring this time of year determines if feed management has cows on track. It identifies whether some cows should be milked once a day, preferentially fed, or dried off early. Remember that cows are able to gain only about half a condition score a month, even with high-quality pasture. Furthermore, no condition is gained in the month leading up to calving due to high energy demands of pregnancy and reduced appetite.

Every kilogram of body weight gain requires about 42 megajoules of metabolisable energy (MJ ME) in a lactating cow and 58MJ ME in a dry cow. 25kg and 50kg live weight per condition score gained are appropriate for adult Jersey and Friesian cows respectively. To increase a 400kg dry Jersey from BCS 4 to 5 in 60 days during autumn, she would need an additional 34MJ ME a day to her normal metabolic requirements. Assuming there is 11MJ ME/kg dry matter (DM) in the pasture, she would need to eat to eat an additional 3.1kgDM.

The information gained from condition scoring your herd is invaluable when making good management decisions.