We look at alternative forage crops and how buffer feed and diet formulations will need attention this spring.
With forage stocks running low, turning cows out onto over-wintered grass could be a viable option if managed carefully.
Generally, the mild winter will mean grass covers are higher than usual. And while removing the over-wintered material will be important to enable a good spring, it is also important to pay attention to rumen function, as otherwise yields and fertility can suffer.
Dr Laura Tennant, ruminant technical adviser with Trouw Nutrition GB, says moving from a largely controlled winter feeding regime to one involving a proportion of grazing will always impact on the rumen, but this is especially true with more mature swards.
“We have received a number of over-wintered grazing samples for analysis and the results suggest there is a considerable range in feed value. On average, overwintered grass is showing about 17 per cent dry matter, 12MJ ME, 43.8 per cent NDF and 7 per cent sugars.
“To support rumen function, it will be important to consider all energy sources, particularly fibre and rapidly fermentable carbohydrates. This is especially important when maize is being fed, as in the latter stages of winter it will feed differently due to improved starch degradability.”
She explains the longer maize silage spends in the clamp the more degradable the starch becomes until it plateaus about eight to 10 months after ensiling.
At lower degradabilities, the rumen bacteria have to work harder to release the starch in the limited time it spends in the rumen, so increased degradability significantly alters how the energy in maize is used.
With higher degradability, there will be increases in both total fermentable carbohydrate in the rumen and also the rapidly fermentable carbohydrate fraction.
At the same time, as more starch is fermented in the rumen there is a reduction in the proportion of bypass starch.
“As a result of starch fermentation in the rumen increasing while the bypass proportion declines, there will be an increase in potential acid loading which could be a problem in diets where cows are already on an acidosis knife edge.”