Sub Acute Ruminal Acidosis

(Yield, Infertility, Composition and Immunity)

For the lactating dairy cow to maximise performance a healthy rumen is critical.

Sub-acute ruminal acidosis (SARA) which is more common to all herds occurs when the rumen pH drops below 5.8 this is sub-optimal for dry matter intake. With SARA there will be fluctuations with intake and reduced performance in milk yield and fertility.

The cow signals that will indicate that there is a potential issue with SARA are outlined below.

Cow signals relating to SARA

• Low milk fat
• Rumen fill – poor
• Dung with gas bubbles
• Undigested fibre particles in the dung
• Laminitis

For most farmers reading this they will say this only relates to cows fed on high concentrate diets and will not be an issue in a grass based system where the cows can look after themselves.

This has proven not to be the case as research carried out by University College Dublin in 2006 by Finbar Mulligan, Luke O’Grady and Michael Doherty with cows 80-150 days in milk on grass showed that 58% of cows had a rumen pH < pH 5.8 which was sub-optimal for dry matter intake, a 11% were < pH 5.5.

In the grazing season of 2011 this was very noticeable from mid-April to mid-July peaking in May, where the butter fat percentage was under the milk protein percentage. What one needs to be careful of here is the average butter fat% reading as an indicator which in a case history on a farm in April was 3.7% but on examining the milk recording sheet up to 32% of cows were at 3.2%, very low. Assess rumen fill and the dung consistency, the signals are there. A cow consuming 17kg DM of grass with sugar readings of 15% – 21% is consuming a diet equivalent to 28% – 38% barley, low in structural fibre, this is a diet high in fermentable carbohydrates.

It is important to note that acidosis yes starts in the rumen but excess acid gets absorbed into the blood so any preventative measure needs to address both. In the indoor period for the lactating cow ensure the forages are high in digestibility and palatability balanced for structural fibre and buffering capacity. This also applies to the grass. Buffers that help sodium bicarbonate, magnesium oxide and yeast.

Nutribio have formulated the Nutri-Buff 270 Range to enhance rumen health and to address the costly issues associated with SARA (yield, composition, infertility and immunity)

Nutribio/CAHL- Nutritionist (Pat O Byrne) BAgSc