Ensuring your cows attain the required pre-calving body condition score (BCS) is an important aspect of building resilience in your herd. Knowing how to assess, identify and improve your cows' BCS will ensure that the benefits of feed grown and herd condition gained up until now are not lost.
In the last several months of gestation, a cow should be fed to maintain her condition as well as to provide for her growing calf. Good planning around drying off and culling is essential, as is regularly checking on feeding levels and BCS — which you can do using the DairyNZ BCS app.
Your main priority is to look after the cows that will be in milk next season. Don't be tempted to milk the cows that are not pregnant for longer, because you believe they'll produce more than their pregnant herd mates. In a six-year study of pregnant and non-pregnant identical twin cows, DairyNZ's principal scientist, John Roche, identified that prior to day 230 of lactation, pregnancy did not affect milk production. In total, pregnant cows only produced 2-3kg milksolids less than non- pregnant cows.
Calving BCS targets are a body condition score of 5.5 for two-year-olds and rising three-year-olds and 5.0 for mature cows.
You can use a variety of strategies to achieve these targets, such as:
* early removal of culls
* early drying off thin cows and low producers
* split herds on age, BCS and 'time until calving'
* stagger drying off based on age, BCS, and 'time until calving'. Remember, rising three-year-olds may still be growing, so some of the feed is going into growth and not into gaining condition
* milking once a day (OAD): approximately 0.25 BCS units' gain over 100 days on OAD milking
* feeding to gain BCS. This may involve purchasing feed.
From March, most cows are 120 to 150 days (North Island) or 150 to 180 days (South Island) away from the planned start of calving. Generally, cows lose some BCS during the two weeks following drying off and cows don't gain BCS in the month before calving.
Therefore, early-calving cows only have a period of 75 to 100 days in which they can gain condition.
Autumn stresses could see your cows exposed to health issues that may not occur at other times, (eg. facial eczema), so ensure they have adequate minerals, eg. magnesium — and if they're feeding on fodder beet, phosphorous. Consider having a health plan for your herd.
This article first appeared in the March 2018 edition of Inside Dairy magazine. Visit dairynz.co.nz/insidedairy
DairyNZ's information and our free BCS app make assessing and identifying body condition scores for your cows much easier. Check them out (and download the app) at dairynz.co.nz/bcs