Back Meeting Cow Condition Score Targets

Date: 15 April 2015

The combination of a dry summer and low supplementary feed usage means many cows are now at, or approaching, drying off with relatively low body condition score levels. The key challenge for many is how to put weight onto cows without spending a lot of additional money on supplementary feed.

If you have a stack of maize silage on hand, now is a great time to consider feeding it. That's because the energy in maize silage is used more efficiently than the energy in autumn pasture for body condition score gain.

The target body condition score at calving is 5.0 for cows and 5.5 for first and second calvers. Meeting cow condition score targets at calving is critical to farm profitability.

Cows calving BCS 4 vs 5 will:
• Take 8-10 days longer to start cycling
• Result in a later calving date next year
• Produce approximately 15 kg milksolids less

Different feeds are used with varying efficiency for body condition score gain (Table 1).

Table 1: Dry cow requirements for one body condition score gain (kgDM/BCS)1

The table shows that it requires less maize silage or grain to put weight onto cows than autumn pasture or poor quality pasture silage.

Will it generate a financially viable return?

Increasing CS from 4.0 to 5.0 will generate a return of around $110/cow (Table 2).

Table 2: Financial benefit of increasing CS from 4.0 to 5.01
If we assume that you can buy in and feed maize silage (including wastage) for 35 c/kgDM, and it takes 200 kg maize silage drymatter to put condition score on a Friesian cow, the total feed cost is $70/cow. So even, if you add on feed-out costs, you should get a good return. Home-grown maize silage is generally much cheaper generating even greater returns.

What to do from here?

The first step is to condition score your herd. Enlisting the help of a qualified rural professional, or even neighbour or two may give you a more accurate assessment. DairyNZ also has an excellent resource freely available to all farmers called "Condition Scoring Made Easy" that will help in this process.

DairyNZ recommendations2 include:

• Dry-off low producing, fat cows early.
These cows put fat on their back instead of milk in your vat. When feed is short, herd milk production commonly increases by drying-off the low producing fat cows, as the other more productive cows are fed better. In addition, there is often an area of low quality feed on the farm where these cows can be put to maintain themselves, such as steep sidelings or gullies.

• Ensure heifers are on track for weight and BCS.
Check every four to six weeks check that replacements are gaining enough weight and remedy any shortcomings. Aim to have these at BCS 5.5 or better when they return from grazing, as they will put little weight on (and often lose weight) while they adapt to being in the herd.

Give the first calvers more time dry than older cows.
Young cows are still growing to reach their mature weight and often have lower intakes. Therefore, they are only able to put weight on slowly and require more time to get to target condition.

• Split dry herds on BCS and time until calving.
If you dry-off all at once then it is necessary to split the dry cows into herds based on condition and expected calving date. This allows for preferential feeding to get all cows to target BCS.

• Staggered dry-off based on BCS and time to calving.
In higher input systems, where dry cows are well fed on a mixture of pasture and supplement, cows that are BCS 4.5 or better only require 50-60 days dry; cows that are BCS 4.0 or worse need around 80-90 days dry.