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June 13, 2022

Fungal contamination isn’t a new problem for day producers, but it’s still a big problem. (See the 2022 yeast and mold counts.)

Here are three ways yeast and mold can impact your dairy operation.

  1. Reduces the feeding value of forages

Yeast and mold start with impacting the forage quality. As the feed is exposed to oxygen, the yeast “wake up” and consume lactic acid — prevalent in forages — as a food source. As these yeast feed off their favorite acid, they begin to multiple and degrade the nutrients in the feed, like carbohydrates and other sugars. Metabolism generates, and the loss of lactic acid raises the pH in the TMR. As the pH rises, the problem compounds as mold and bacteria become active and consume additional carbohydrates and amino acids, resulting in more heating. At this point, the producer faces massive spoilage and a less nutritious TMR.

  1. Directly alters rumen fermentation

Consuming spoiled feed can hinder the rumen from completing its job — fermentation.  Recent research evaluated the impact of wild yeast (Issatchenkia orientalis) on fiber digestion using an in vitro ruminal fermentation model. In this model, scientists contaminated rumen fluid with three concentration levels of wild yeast:

  • Control (untreated)
  • Low (4.40 log10 CFU/mL)
  • Mid (40 log10 CFUmL)
  • High (8.40 log10 CFU/mL)

At 12 hours, the high-yeast treatment had reduced neutral detergent fiber digestibility (NDF-D) from 43.9% in the control, down to 33.9% — a reduction of 23%. At that same time interval, the mid-yeast treatment was 7.3% lower than the control, and the low-yeast treatment was not altered compared to the control. These findings suggest that when cows are fed silage with high populations of wild yeast (I. orientalis wild yeast), it can disrupt ruminal fiber digestion. (Santo and collaborators 2014)

  1. Lessens the efficiency of cattle

Windle and Kung (2013) evaluated dry matter intake for heifers fed fresh or spoiled total mixed rations (TMR). The heifers fed the unspoiled TMR consumed 11.69 kg (25.77 lb.) of dry matter per day. The heifers fed the spoiled TMR consumed 10% less dry matter for a total intake of 10.54 kg (23.24 lb.). This study further confirms that mold spoils TMR and impacts feed intake and efficiency.

Another study demonstrated the impact spoiled feed has on intake, production, and rumen performance and health. In this study, cows were fed high-moisture corn contaminated with mold to evaluate the impact on milk production. Below is a summary of the results:

  • Cows fed a ration with around 10,000 colony forming units per gram (1 x 104 CFU/g) produced 31.7-32.2 kg (70-71 lb.) of milk per day
  • Cows fed ration with around 100,000,000 (1 x 108 CFU/g) produced 30.0-31.3 kg (66-69 lb.) per day

This resulted in a loss of 35-45 lb. of milk loss during this two-week period. (Hoffman and Ocker 2017)

The bottom line? Yeast and mold may be eating at your profits and QLF can help. Find your local QLF representative today to talk through options that may be best for your herd.

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