Cows should be treated as ruminants for feed

Dairy farmers need to stop thinking of cows as pigs when it comes to feeding and start thinking of them as ruminants, delegates heard at the inaugural National Forage Conference last week.

Speaking at Hartpury College, Gloucestershire, nutritionist Mary Beth de Ondarza explained how it was important farmers understood rumen function to maximise forage efficiency.

She said too often she saw cows with inconsistent manure; either too stiff or loose and bubbly. When this is the case, she added, it was likely the cows were suffering from subclinical acidosis (SARA) – a condition that occurs when the pH of the cow’s rumen drops below six and at a cost to the farmer.

“While cows may be yielding well and appearing healthy when they have inconsistent manure there is easily another 1-2kg of milk to get in the tank,” she warned.

Dr Ondarza explained that the perfect pat from a high-producing cow should look like a pile of shaving cream, having three to six rings, standing up about 1.5 inches, with a dimple in the middle. But she admitted it wasn’t always easy getting the right balance.

“It’s a true balancing act to provide proper nutrition to high-producing dairy cattle while also keeping their digestive systems healthy. Diet is a major factor affecting the incidence of rumen acidosis and attention must be made to dietary starch and sugars, the speed of starch digestion, dietary fibre and the amount of chewable fibre in the diet.”

But even when the perfect diet has been formulated, feeding management must be right. Dr Ondarza suggested feeding little and often to even out the fluctuations in rumen pH, but warned even when cows had access to ad lib, TMR problems could still occur.

“When there are problems with TMR consistency, sorting can be a problem. Also when cows are submissive, or there is inadequate trough space, uncomfortable resting surfaces or heat stress, feeding behaviour will be affected.”

Research showed that when 99cm of feed space versus 51cm of feed space was offered, cows with more feed space had 57% fewer hostile interactions and 10% more eating time a day. “It is vital you get all the factors right in order to create a stable ruminant environment,” she added.

And with more farmers including forage in the diet as a result of increasing grain costs, Dr Ondarza explained the benefits feeding more highly digestible fibre and less grain could have.

“Feeding highly digestible forage can help provide more energy for the cow and also promote intakes. When ration grain levels are reduced and adequate fibre is provided, rations containing high digestible Neutral Detergent Fibre (NDF) can reduce the incidence of SARA, improving rumen health and cow productivity.

But how much forage NDF is best for the cow and the pocket? Dr Ondarza suggested producers included enough total highly digestible NDF and chewable/tougher NDF in the form of hay and straw to maintain the rumen balance.

“About 15% of the ration should contain particles greater than 1.5 inches and a typical high yielding cow ration containing highly digestible forages should contain about 26-27% NDF. Grain levels can then be reduced.” But as a lasting message Dr Ondarza stressed the importance of getting forages tested for digestibility.