Modification of in vitro multi-enzymatic method for determining the organic matter digestibility of feeds
In vitro multi-enzymatic method for the determination of organic matter digestibility (OMD) of feeds for ruminants used in this study is an underutilised method but with a high potential to be routinely used. One of the enzymes used in this method was commercial enzyme Novozym 51054, but it is no longer produced. Therefore the aim of this study was to replace Novozym 51054 with an alternative enzyme, as well as to verify that the values of OMD obtained using an alternative enzyme do not differ significantly from the previous available enzyme. The selected enzyme was mannanase, under the commercial name of FFE-2010-00167 (Novozymes, Denmark). Ten samples (complete feed, barley, sunflower meal, straw, maize, wheat bran, sorghum, soybean meal, rapeseed, sugar beet pulp) were analysed in 10 replicates using both enzymes. Determined OMD values ranged from 32.60 % for straw to 97.60 % for soybean meal. Replacing Novozym 51054 with mannanase led to similar OMD values of the analysed samples (p = 0.976). Results obtained from both enzymes indicate a good fit by regression analysis, which was also confirmed with the low value of standard deviation of the residuals (SD=0.39). Thus it can be concluded that Novozym 51054 may be replaced with mannanase FFE-2010-00167 in in vitro multi-enzymatic method for determination of OMD in feeds for ruminants.
The in vivo measurement of feed digestibility requires animals, relatively large quantities of test feed and time. Therefore it is too costly, labour intensive and protracted to be routinely used. There was a constant search for rapid and inexpensive laboratory methods for routine prediction of the in vivo organic matter digestibility (OMD) of ruminant feeds. There are several laboratory procedures used to predict OMD of feeds for ruminants and they are based on chemical analysis, fermentation with rumen microorganisms or hydrolysis with enzymatic preparations. An example of prediction of digestibility from chemical composition was shown by Sauvant et al. (1). They studied prediction models based on cell wall parameters (crude fibre, NDF, ADF) in different feed materials used in ruminant nutrition. Feed materials were divided in six groups; therefore, six major prediction models were generated. R2 value of prediction equations ranged from 0.74 to 0.98, and many of the resulting equations had crude fibre as the main predictor. According to other authors (2-5) proximate Weende crude nutrients have poor capacity to predict in vivo digestibility ...