Yeast growth in silage is generally a bad thing. It results in heating, dry matter (DM), nutrient and energy losses and can cause the pH to increase, allowing spoilage molds and bacteria to grow, reducing silage quality even more and possibly resulting in toxin production.
Whenever producers see excessive heat, they can be sure that the nutritive value of the silage is declining as well. Yeasts are relatively simple organisms, and so they use the most digestible and valuable nutrients first.
The best solution to avoiding these losses is minimizing yeast growth. Yeasts need oxygen to thrive. Therefore, limiting oxygen exposure is key to inhibiting heating and spoilage.
Limiting oxygen exposure is hard work. Producers must be sure to pack efficiently and cover completed bunkers and piles quickly and completely. This helps drive air out at ensiling and reduce its ingress, in addition to limiting the growth of the more exothermic aerobic microbes.
The danger of heating and spoilage returns at feedout when silage is again exposed to air, which can cause yeasts —dormant during storage — to ‘wake-up’ and grow rapidly, causing considerable heating and feed losses. To minimize these losses, be sure to use good face management. Avoid removing silage too far ahead of feeding, do not leave silage sitting in loose piles and feed out at a rate fast enough to avoid heating.
Silage inoculated with Lactobacillus buchneri 40788 will be more resistant to heating and spoilage as this organism reduces yeast levels, improving feed stability. L. buchneri 40788 applied at a minimum of 400,000 CFU per gram of silage or 600,000 CFU per gram of high-moisture corn (HMC), has been uniquely reviewed by the FDA and allowed to claim improved aerobic stability.
Using these strategies as part of you overall silage management program can help minimize yeast growth, retaining more valuable nutrients for cattle to help increase profitability.