Mark McFarland, product manager at Lallemand Animal Nutrition, says taking the time to understand and maximise the digestibility of fibre in your winter feed will pay dividends.
“Unlike monogastric animals, ruminants have a unique ability to release a significant amount of energy from the fibre fraction of forage,” explains Mr McFarland.
“Fibre is slowly broken down in the rumen by a diverse population of bacteria, fungi and protozoa, leading to the production of volatile fatty acids (VFA’s). Via this process, there’s the potential to generate 70 percent of the energy required for milk production.
“Acetic acid – one of the VFAs produced – is also an important precursor of milk fat, which is why reduced fibre digestion is often the culprit in situations where milk fat dips.”
He says the ability of the cow to break down and utilise fibre is linked to both the quality of the forage and the fibre digestion process once it is fed.
What is fibre?
“Fibre is made up of three components – cellulose, hemicellulose and lignin – of which only two are digestible in the rumen. Cellulose and hemicellulose are digestible; however, lignin is not,” says Mr McFarland.He explains the starting point is therefore to try and produce forage with an optimal lignin content and this means harvesting the plant at the right stage of maturity.
While it is too late to influence the quality of this year’s silage, Mr McFarland says the focus should now be on maximising neutral detergent fibre (NDF) digestibility within the rumen.
“Optimum fibre digestion in the rumen leads to higher production and more fertile and healthier animals,” he says.
“Research shows that for every 1% increase in NDF digestibility, fat corrected milk (FCM) increases by 0.25kg a day.”
Maximising the value of fibre
“The physiological status of the animal has a big impact on ruminal fibre degradation and can be influenced by factors such as environmental temperature, stocking density and feed and water access,” explains Mr McFarland.“But how and what a cow is fed is the biggest contributor to how efficiently the rumen breaks down valuable fibre. Working closely with your nutritionist and/or feed advisor is therefore a must.”
What to do if silage is dry?
Those with dry silage are advised to take steps to improve forage palatability and reduce sorting, while those with wet silage should balance rations with drier feeds to boost dry matter intake (DMI).“Eating high dry matter (DM) silage is challenging; it’s like eating a dry breakfast cereal without any milk. Feed intakes will therefore likely reduce,” explains Mr McFarland.
“Sorting can also be an issue in high DM total mixed rations (TMRs), leading to an increased risk of acidosis. Adding water to the ration is a simple, yet effective, way to address this.”
Farmers with drier silages are also more likely to experience problems with heating and mould growth due to drier forages being more difficult to compact, adds Mr McFarland.
What to do if silage is wet?
In instances where silage is wet, he says cows will struggle to receive the same DM from wet silage as they could get from drier silage.“Wet silage also tends to create an increased acid load in the rumen, due to higher lactic acid concentrations in the silage, so farmers should look to balance wet silage with drier silages such as wholecrop cereal silage if it’s available,” he adds.
Feeding a rumen specific live yeast
Mr McFarland says farmers should also consider the inclusion of rumen specific live yeast in the diet as a way of both improving fibre digestibility and reducing the risk of acidosis.“Live yeasts are generally used in animal nutrition for their probiotic effects,” says Mr McFarland.
“This helps control rumen pH, reducing the risk of acidosis, and significantly improves fibre digestibility within the rumen compartment.”
He says trials show cows fed Levucell SC as part of their ration experienced an average increase in milk yields of 1.1kg per day, as well as a 3% improvement in feed efficiency.
“Many farmers are still missing out on the significant potential that fibre from forage offers,” concludes Mr McFarland.
“By taking the time to understand the importance of fibre and taking steps to improve its digestion in the rumen, farmers can get more litres in the tank at minimal cost.”
Top tips to improve fibre digestion in your dairy herd
- Feed little and often – aim to feed more than once a day, and push up feed regularly, to increase meal frequency. This improves the stability of the rumen by reducing the extent and duration of reductions in rumen pH, which typically occur after a large feed
- Focus on timing – cows are naturally stimulated to eat after milking so push up existing feed and time fresh feed provision between milking times and not straight after to increase meal frequency.
- Avoid overcrowding – pay close attention to your stocking density because competing for feed at the barrier or limited eating time reduces intakes. Aim to have a barrier space of 1m per cow during the dry period and at least 75cm per cow in the fresh group
- Feed a rumen specific live yeast such as Levucell SC – this will support beneficial rumen microbes, help balance the rumen environment, and improve rumen fermentation conditions
- Provide free access to salt – a cow naturally balances the pH of her rumen by producing sodium bicarbonate in her saliva while she is cudding. Giving her free access to salt supports this process
