The lush, leafy swards typically seen at this time of year are great for milk production and milk proteins.
However, this highly digestible grazed grass is generally rich in rapidly fermented sugars and low in structural fibre content, and can lower rumen pH and promote a condition called SARA – sub-acute rumen acidosis.
This impacts significantly 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.
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 cudding well?
Are cows lying down ruminating? More than 65% of the herd should be ruminating two to three hours after milking unless they are drinking or actively grazing.
Drool and saliva should be observed around the muzzle, with greater than 65 chews per cud where strong rumination is evident.
Are cows losing weight?
Excessive weight loss could be a result of sub-optimal rumen function as a result of 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?
Milk quality and yield – if you notice a 0.3%-0.5% drop in butterfat over a week or a 0.3% drop in protein, then this could indicate SARA.
If milk yields drop by around 2-3L/cow/day over the course of a week then this can also indicate acidosis problems.
Look at individual milk recording data – if more than 10% of the herd has a higher milk protein than milk fat % this indicates a potential problem with SARA. Averages can be misleading.
The cost of butterfat crashes
The below table illustrates the effect on profitability of a sharp drop in butterfat levels on a 100-cow herd over the course of one month.
*Irish milk pricing based approximately on €6.70/kg protein and €3.50/kg butterfat. Fixed processing cost of 4c/L
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.
Actisaf significantly improves rumen efficiency, leading to increased digestion and utilisation of grass, and promotes a stabilising effect on rumen pH, reducing the threat of SARA.
Phileo Lesaffre UK and Ireland recommends that Actisaf is included at a minimum rate of 1kg Actisaf per tonne, with an estimated cost of €10/t.
Further information
Find out more about SARA at grass and how Actisaf can help by watching the short video below.
Alternatively, you can read Phileo Lesaffre’s guide to how Actisaf reduces the risk of SARA at grass by clicking here
As well, you can read about how these farmers have seen the benefits of using Actisaf at grass by clicking here
