Do your herd’s milk constituents suffer when grazing?

After a hard winter and late spring, most dairy farmers are grateful that the weather has finally improved and grazing can begin in earnest.

Many swards will have been damaged by grazing during the wet ground conditions, which may affect sward productivity throughout the season.

However, most swards will recover now the ground is drying; once they do, the lush, leafy swards typically seen at this time of year can support the production of high levels of milk solids.

But one difficulty with highly-digestible grazed grass is that it is generally rich in rapidly-fermented carbohydrate and low in structural fibre content.

This can lower rumen pH and promote a condition called SARA (sub-acute rumen acidosis). This significantly impacts on rumen efficiency, herd performance and fertility. What’s more, SARA can have a significant impact on milk solids yield and, consequently, milk price.

It can often go undetected, but there are some simple warning signs that you can look out for that can indicate a potential problem with SARA in your herd at this time of year.

Look at the dung

Is dung loose with gas bubbles in it? This can suggest excess production of acids in the rumen, due to the rapid fermentation of grass resulting in SARA (also check protein and magnesium levels and for liver fluke).

Are there undigested fibre particles in the dung? This can suggest reduced rumen digestion, due to lowered pH (also check for energy and protein content relative to milk yield and stage of lactation, as low protein can also cause this).

Also look for cud balls (in collecting yards at milking), which are an indicator of poor rumen function.

Assess rumen fill

Look at rumen fill three-to-four hours after morning milking; poor rumen fill can be caused by reduced dry matter (DM) intake, due to acidic conditions in the rumen (also check for low-DM grass and high-protein grass, as this can also cause poor rumen fill).

Are cows losing weight?

Excessive weight loss could be as a result of sub-optimal rumen function, due to SARA causing a drop in dry matter intakes. Excess body weight loss predisposes cows to several disorders including: lameness; ketosis; milk fever; fatty liver; and poor fertility.

What’s happening with milk quality?

If you notice a 0.3-0.5% drop in butterfat over a week or a 0.3% drop in protein, this could indicate SARA. If milk yields drop by around 2-3L/cow/day over the course of a week, this can also indicate an issue with acidosis.

Look at individual milk recording data; if more than 10% of the herd has a higher milk protein than milk fat percentage, this indicates a potential problem with SARA.

Don’t just rely on the bulk tank average for butterfat and protein percentages, as averages can be misleading.

The solution?

If you suspect SARA in your herd then research has shown that you can reduce the risk by adding Actisaf Sc 47 live yeast to your compound feed at a minimum rate of 1kg/t of feed, which is sufficient for a 4kg compound feed rate.

Actisaf significantly improves rumen efficiency, leading to increased digestion and utilisation of grass. It also promotes a stabilising effect on rumen pH, thus reducing the threat of SARA.

Find out more about SARA at grass and how Actisaf can help by watching the video below:

For more information on how Actisaf reduces the risk of SARA at grass, Just click here