After a challenging growing season in many parts of the UK, forage supplies are under pressure, making efficient use of available feed increasingly important. While later grass growth and forage crops may help extend supplies on some units, producers finishing lambs into the autumn and winter may need to look more closely at how they balance forage with concentrates and cereals.
Highly digestible, cereal-based diets are a great tool to push energy intake and drive finishing performance, particularly when forage is limited. However, increasing cereal inclusion generally increases dietary starch levels, placing greater pressure on the rumen and increase the risk of sub-acute ruminal acidosis (SARA).
Unlike acute acidosis, SARA can develop without obvious signs. Lambs may continue eating and appear healthy, while daily liveweight gains become inconsistent, feed conversion efficiency deteriorates and variation within finishing groups increases. In practical terms, this can mean more days to finish and less predictable returns.
The engine behind lamb performance
"The rumen is home to trillions of microbes that break down feed through fermentation, producing volatile fatty acids which provide 60-70% of the energy a lamb needs to grow and maintain itself," explains Kevin Doyle, technical manager, Phileo UK & Ireland.
"These microbes serve as the engine room of the lamb. When they function efficiently, lambs can use nutrients more effectively to support growth.
"Rapidly fermentable diets, however, can produce acids faster than they can be absorbed or buffered. This causes rumen pH to fall, and fibre-digesting microbes become less active, reducing feed efficiency.
"At the same time, the lining of the gut can become damaged which causes a number of knock-on effects that hit lamb performance."
The importance of fibre
Sufficient effective fibre is essential for good rumen function. Fibre encourages chewing and saliva production, helping to naturally buffer the rumen and maintain a more stable pH. Work with your feed adviser to establish minimum effective and digestible fibre levels needed for your herd and situation.
This becomes particularly important when lambs are being fed cereal-rich finishing rations.
Cereals such as wheat and barley provide readily available energy. However, their rapidly fermentable starch can increase the risk of rumen instability if the overall diet is not properly balanced adequate with fibre supplied from forages and digestible fibre sources in the blend or compound.
Headline nutrient figures are only part of the picture. The source, quality and balance of protein, starch and fibre can all influence rumen function and performance.
Understanding forage quality and working with a nutritionist or feed adviser can help ensure the complete diet is appropriately balanced and formulated for their farm's specific circumstances.
Small changes, hidden costs
Sudden dietary changes, inconsistent feeding, variation in forage or concentrate intake and competition for feed space can all destabilise the rumen. Even relatively small inconsistencies can affect rumen efficiency over time.
"When it comes to protecting rumen function, consistency is king," adds Kevin. "When moving lambs from forage-based diets to finishing rations, dietary changes should be made gradually over two to three weeks. This gives the microbial population within the rumen time to adapt to the new diet."
Consistent feeding routines, sufficient trough space, adequate effective fibre and avoiding situations that encourage lambs to consume large quantities of concentrate at once can all help maintain a more stable rumen environment.
Supporting the rumen microbiome
Alongside good ration formulation and feeding management, targeted nutritional strategies can help maintain rumen function when cereal inclusion is relatively high.
Actisaf庐 Sc 47 live yeast probiotic helps maintain a stable rumen environment and supports the microbes responsible for digesting fibre and utilising lactic acid.
Through this dual mode of action, Actisaf庐 can help lambs make better use of their diet, particularly when the rumen is under greater pressure. Research has shown improvements in feed efficiency, up to 8% heavier carcass weight and 10% higher average daily gain 鈥� all contributing to a farm's bottom line.
On-farm results
Martin Taylor-Lloyd saw the benefits of Actisaf庐 first-hand while formulating a new ration to support growth performance targets with his feed adviser. As they increased starch and sugar levels, lambs were growing 400g per day, but started to show signs of acidosis.
"Once we tweaked the ration and added more Actisaf, lambs became far more settled, and performance lifted again," explained Martin. "We're now consistently seeing between 400-500g DLWG, which is enabling us to get lambs finished quickly and give us the three-week turnaround we need."
