Target next season

By Samantha Tennent

Actions taken now can have a big impact when calving rolls around again

If cows don’t achieve body condition score targets at calving they will produce less and it will impact their reproductive performance as well as their health and welfare. There is also evidence that BCS in early lactation can affect the sex of future calves and the productive and reproductive capacity of heifers yet to be born. That’s why it is so important to be monitoring cow condition as the season tails off, as actions now can have a big impact on next season.

The most common reason for not reaching BCS targets is not allowing enough time. Utilising predicted calving dates, BCS results and feed inventory, farmers can make plans around individual cow management and there are a few things to consider. The four main strategies to help achieve individual cow BCS targets at calving (5.0 for mixed age cows and 5.5 for first and second calvers) include increasing feed allocation to lactating cows, reducing milking frequency in mid-late lactation, drying-off cows early, and/or feeding dry cows for BCS gain.

Although a lactating cow requires 25% less energy to store fat or gain a BCS unit than a dry cow, genetic selection over time has resulted in cows that partition energy to milk production at the expense of BCS while they are being milked. Which means a lactating cow requires more actual feed to gain BCS compared with a dry cow. Feeding an additional 150kg DM over 100 days will increase BCS by 0.25 units in a late-lactation cow compared with 1.0 BCS unit in a dry cow. Reducing milking frequency to oncea-day (OAD) or using a flexible system for a longer period, like milking three times in two days (3in2), can improve BCS at dry-off while achieving longer lactations. Because energy requirements for walking and milk production are reduced, it is key to maintain a similar feed allocation as that given when the cows were being milked twice a day so there is energy available for BCS gain.

Drafting cows into mobs, based on BCS, age and expected calving date, allows the right mix of approaches to be applied to cows with similar gains in BCS required.

Immediately after drying off, cows rarely gain BCS in the first couple of weeks and sometimes they may lose BCS during this period, mostly because feed is being restricted to reduce milk production.

On our pasture-based systems, cows will only gain 0.5 BCS per month on average during the dry period and 0.60.7 BCS units per month if fed a diet containing high levels of supplement or high-energy crops. And in the last month before calving, dry cows will gain very little BCS (less than 0.1 BCS units) because of the large energy demands and inefficient use of nutrients by the growing calf.

There can be a trade-off of autumn milk production if cows at risk of not achieving BCS targets are dried off early, but the gain in production the following spring, as well as the additional benefits to reproductive performance and health, create balance. They also may not end up empty and give the farmer options for culling the following season.

All of these reasons need to be taken into account when determining when a cow should be dried off. The length of the dry period required for cows to reach BCS targets at calving will be determined by how much BCS they need to gain, the amount of feed available and the type of feed that will be offered during the dry period.

Use a certified BCS assessor to accurately score your herd and put the information into WelFarm to monitor how your herd is tracking. Use your support network to devise plans to ensure your cows achieve their targets, and you can optimise productivity and profitability next season. n

Who am I?

Samantha Tennent is the general manager of Welfarm Ltd.