Submitted to: Hay and Forage Grower
Publication Type: Popular Publication
Publication Acceptance Date: 3/15/2021
Publication Date: 4/28/2021
Citation: Coblentz, W.K. 2021. Baleage fermentation is complicated. Hay and Forage Grower. P. 20-22, April/May 2021.
Technical Abstract: Managing the moisture concentration of baled silages is an important consideration in properly conserving high-quality forages for later cash sale or use in livestock feeding operations. However, there are probably more aspects to this issue than are normally considered. It has long been understood that a major driver within any silage fermentation is forage moisture, but is that always good? If not, when is it a problem? Why? Can baled silages be too dry? Why, or why not? Over the last decade, approximately 10 different research trials with baled silages have been conducted at the University of Wisconsin Marshfield Agriculture Research Station that produced 283 silage bales. Lactic and total fermentation acids within these bales were regressed against bale moisture. A couple of points are worthy of emphasis: i) despite the differing experimental goals and conditions within these studies, bale moisture explained about 2/3 of the variability in the data set; ii) concentrations of total fermentation acids are highly variable, particularly across studies; iii) fermentation acids increase with bale moisture; and iv) relatively little fermentation occurs when bale moisture is <45%. The relationship between lactic acid and bale moisture closely resembled the pattern observed for total fermentation acids; however, concentrations of lactic acid may be quite low, or even undetected, when bale moisture is < 45%. Producers may wonder why wetter bales might not be a better management strategy, since fermentation is enhanced by moisture. However, there are several reasons why bales exceeding 55% moisture may be problematic. These include obvious bale weight and associated safety issues, but also baler design, where balers still generally handle dry forages better than wetter ones. However, the main reason why moisture recommendations for baled silages are lower (drier) than chopped silages is the potential for clostridial fermentations that yield (undesirable) ammonia and butyric acid, and reduced voluntary intake. While limiting moisture within silage bales is an effective deterrent to clostridial activity, use of bacterial inoculants for this purpose also makes logical sense, but research evaluations are very limited.