With research showing a minimum of 5 per cent ration sugars is needed to fully support rumen function, choosing the right feeds to supply those sugars is going to be critical to maximising milk from forage and income over feed costs (IOFC) this winter.
Mark Scott, KW senior nutritionist, says feeding additional sugars has been established as having a significant effect on both fibre digestion and the ability of rumen microbes to convert rumen degradable protein – such as that predominantly found in grass and grass silages – into protein which is available to the cow.
“Getting the supply of sugars right is therefore critical to getting the most out of conserved forages this winter, and to feed efficiency overall.
“Even a 3 per cent drop in rumen efficiency through incorrect energy balance can increase feed costs for a typical 200-cow herd by £568/month, equivalent to 0.35ppl, based on an average yield of 27 litres/cow/day.
“Yet it is possible to lift the sugar content of most rations above the minimum threshold for half this potential loss by feeding 6.75kg fresh weight/cow/day of a high-lactose liquid feed, for example.”
Research from the United States shows early-to-mid lactation dairy rations should contain 5-7 per cent fermentable sugars (on a DM basis) in order to fully support microbial breakdown of forage fibre in the rumen. These sugars will also increase utilisation of the high levels of effective rumen degradable protein (ERDP) in grass silages, improving efficiency and reducing potential waste and losses to the environment.
As Mr Scott points out, both are highly relevant to the 2016 grass silages being seen across the country, with the latest Trouw Nutrition data showing increased levels of digestible fibre (neutral detergent fibre, NDF) and crude protein compared to last year.
“Unfortunately, large numbers of the forage-based rations fed in the UK contain only 3-4 per cent sugars,” says Mr Scott. “Not only that, but many of these are residual sugars in preserved forages, which are not particularly accessible to the rumen microbes.
“Including feeds in the ration that supply additional sugars is therefore extremely important, and the key to doing this cost-effectively is the right choice of feed.”
It is possible to increase ration sugar levels by replacing cereals with a confectionery or breakfast cereal blend, for example, or by using molassed sugar beet feed to supply digestible fibre (Table 1). But the impact is relatively small, claims Mr Scott, particularly when compared to adding a high-sugar liquid feed like a high-lactose liquid feed or one of the many cane molasses blends, which contain up to 85 per cent sugars.
"Getting the supply of sugars right is critical to getting the most out of conserved forages"- Mark Scott
“These liquid feeds also have a very low substitution rate, so the extra sugar can be added to the ration with minimal displacement of other feed ingredients. Plus they’ll further increase nutrient intake – and milk output – by stimulating additional ration consumption, and reduce ration sorting.
“Just make sure you introduce the additional sugars slowly, allowing time for the rumen to adapt,” he adds. “And aim to maintain a balance in the rumen by keeping the starch-to-sugars ratio at around 3:1.”
Another option is to use a high-protein liquid feed as an alternative to more traditional protein feeds (Table 2). According to Mr Scott, using 2kg freshweight (FW) of a high-protein molasses blend to replace the crude protein supplied by 1.4kg FW of a typical 50:50 soyabean meal-rapemeal mix would boost ration sugar levels by two percentage points.
“Care does need to be taken to ensure rations remain balanced, as liquid feeds do no contain as much rumen-bypass protein as rapemeal or soyabean meal. But if the rations are adjusted to maintain nutrient supply, this can be a cost-effective way to add sugars to the ration.
“Forage is still the cheapest feed on farm, so it makes a lot of sense to get the most of it by keeping available sugar levels above that 5 per cent threshold. In fact, fine tuning all the factors which affect rumen function should be a top priority this winter to squeeze every ounce of value from the feeds in the ration and really drive IOFC as high as you can.”
|Dry matter (%)||Energy (MJ ME/Kg DM)||Starch (% DM)||Sugar (% DM)|
|High-lactose liquid feed||23||13.5||-||85*|
|Cane Molasses blend||60||13.4||-||54|
|Breakfast cereal blend||87||15.5||40||23|
|Molassed sugar beet feed||89||12.5||1.0||20|
*Sugar as lactose
|Dry matter (%)||Energy (MJ ME/Kg DM)||Protein (%DM)||Sugar (% DM)|
|High-protein molasses blends||60-69||11.8-12.4||44-50||42-55|
|Hi-pro soyabean meal||89||14.0||54||10|