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The proof is in the cudding


Not all yeasts are created equal; strains differ the same way breeds of cow differ. Some yeasts can significantly improve feed efficiency and fertility, while others are less able to do so. For cows to be able to realise more potential from feed, producers are advised to feed the right strain in the right amounts.  

Live yeast vs. dead yeast 

All yeasts “feed” rumen bacteria, but live yeast also actively scavenges oxygen in the rumen.  Oxygen is toxic to the anaerobic bacteria that break down feed in the rumen, so less oxygen means more active bacteria, better digestion, better feed efficiency and more milk or live-weight.  

Dead (or “stabilised”) yeast does not have the ability to use up oxygen in the same way live yeast does, and copious evidence exists proving that live yeasts are still alive in feed and minerals.  

Fibre digestion and acid 

Different yeast strains stimulate different groups of bacteria. Some bacteria in the rumen break down fibre while others “mop up” acid. Alltech’s Yea-Sacc® has the advantage of stimulating both groups, resulting in increased average rumen pH at a less varied rate for longer periods.  

Dr. Alex Bach, IRTA, Spain 

So, how can we easily assess fibre digestion on-farm? First, look at the cows: Are 80 percent of your cattle lying down and cudding when they’re not eating or drinking? Next, assess dung consistency across the herd: Is the dung consistently firm enough to form a thick, domed pat, and do you hear a slow clapping sound upon defecation? Alltech promotes the use of dung sieves to achieve more accurate measurements.  

The image below shows large, undigested particles trapped in the top sieve (left) versus smaller particles on the right. If we were to take this picture again three weeks after adding Yea-Sacc® to the diet, we would see fewer large particles in that top sieve — more specifically, a decrease of as much as 50 percent.   

Which strain of yeast is the best? 

Everyone says theirs is the best, don’t they? After all, has anyone ever pulled into your farm yard to tell you they have the second-best product on the market? Fortunately, however, you don’t have to take anyone’s word for it regarding yeast, as every strain of yeast must be registered with the European Food Safety Authority (EFSA). As part of this registration process, companies must prove that their product is both safe and effective. Each yeast strain is then registered at a certain strength and benefit for beef, diary, sheep or pigs. 

In official studies, Alltech’s Yea-Sacc® helped increase average milk production by 1.4 litres per cow per day, and the beef trials submitted to EFSA showed an improved feed efficiency of up to 12 percent.  

Other yeasts on the market have failed to demonstrate this level of efficacy for either beef or dairy species.  

Yea-Sacc® offers more with less  

Some yeasts are stronger than others, meaning you need to utilize less (as per the official levels set by EFSA). Since Yea-Sacc® is the strongest, you will definitely need less. Don’t let anyone else tell you their yeast is better simply because there is more yeast in the bag; there is more yeast in the bag because EFSA has determined that the strain is weaker.  

How can I avoid wasting my money on yeast? 

Ask for Yea-Sacc® by name, and look for the code number CBS 493.94 on the label of your compound feed, minerals or blend.  

For nutritional queries or to arrange a dung sieve assessment, please call us on 01780 764512.  



Bob Kendal, Ruminant Manager (North)  


Tel: 07885 280691