Incorrectly balanced beef finishing rations could reduce dry matter intake, leading to decreased liveweight gain and profit margins.
Poorly balanced intensive beef finishing rations could reduce dry matter intake (DMI) by up to 10 per cent, cutting liveweight gain (LWG) by 90g/day, extending finishing times by up to seven days and reducing margin over feed (MOF) by £39/head.
That is the message from KW nutritionist Dr Anna Sutcliffe.
She says: “With plenty of low-cost cereals available and pressure to keep feed costs low, there is a real danger finishing rations will end up overloaded with starch this winter.
“Unless those rations are properly balanced, margins will be reduced rather than increased, as rumen fermentation is disrupted and both DMI and daily LWG drop.”
In addition to slowing growth rates and increasing overall feed costs, incorrectly balanced rations also make it difficult to achieve the level of finish needed to meet typical supermarket supply contracts. The result is a further reduction in margins as income is cut due to carcases falling below target specification.
Dr Sutcliffe says: “The key is to balance the fast rate of starch fermentation in the rumen with other feeds to create a sustained release of energy.
“This not only best supports microbial activity and maximises capture of the protein in the ration, but it also minimises the rumen pH drop which is so damaging to DMI.
“Just remember although straw is great for stimulating good rumen function and rumination, it is no substitute for a good supply of digestible fibre (NDF). Sugar beet feed is still the best option to buffer rumen pH, though soya hulls are proving popular at current prices and the co-product moist feeds are always a great value source of digestible fibre.”
With straw taking up to 72 hours to be fully fermented in the rumen, a minimum of 25 per cent NDF is typically needed to buffer the acid produced by rapidly fermented starch and provide a source of mid-rate energy release.
In a 2009 trial carried out at Harper Adams University, dairy-bred bulls finished on a ration using a mid-protein wheat gluten moist feed to boost digestible fibre supply finished at heavier slaughter weights with a lower overall feed cost per kg of LWG and an increase in margin worth £39/head.
Dr Sutcliffe says: “The improvement in rumen function is confirmed by the significant 39 per cent reduction in liver damage score.
“Liver abscesses are typically associated with acidosis from over-feeding starch, so there was clearly a reduction in acid overload in the rumen thanks to a better balanced release of energy.”
According to Dr Sutcliffe, the sugars in many liquid feeds also have an important role to play. Sugars extend the time energy is available to rumen microbes by fermenting even more quickly than starch, but without producing the lactic acid responsible for lowering rumen pH and triggering acidosis.
She says: “Liquid feeds are also great for reducing ration dustiness, binding the various ration ingredients together and increasing overall ration moisture content and palatability. And using a higher protein liquid feed – such as a urea-based molasses blend – can be a really cost-effective way to boost protein content in rations based heavily on cereals plus straw, or those relying heavily on maize or wholecrop cereal silage.
“However, it is important to keep the starch-to-sugars ratio to around 3:1 to maintain balance in the rumen. If the total ration starch-plus-sugars content is more than 35 per cent, it is likely a live yeast will be beneficial to help keep acidosis under control.”
The yeast will also benefit rations based on wheat, rather than barley, due to the more rapid rate of fermentation in the rumen. Research trials have shown a 4-6 per cent improvement in FCE and an 8-10 per cent increase in growth rate when adding a live yeast to the rations of intensively finished beef cattle, equivalent to extra LWG of about 100g/day, she says.