Simulation of rumen fermentation kinetics of by-products from the biodiesel industry with in vitro gas production technique

Abstract

The objective of this study was to investigate the rumen fermentation kinetics of 18 by-products from the biodiesel industry exhibiting potential for use in the feeding of ruminants via the in vitro gas production technique. The following feeds were investigated: cottonseed, canudo de pito, crambe, sunflower, castor seed (detoxified with lime) and soybean meals and cottonseed, peanut, babassu, crambe, palm kernel, sunflower, licuri nut, macaúba, forage radish and jatropha cakes. The evaluated parameters were total gas production (VfT), gas production from fibrous carbohydrates (VfFC), gas production from non-fibrous carbohydrates (VfNFC), the degradation rate of fibrous carbohydrates (kdFC), the degradation rate of non-fibrous carbohydrates (kdNFC) and lag time (lag). The feeds were grouped into six different groups according to rumen fermentation kinetic parameters and adopting an R2 of 0.8. Forage radish cake and the meals of cottonseed, soybean, crambe and sunflower composed the first group, while the cakes of babassu and sunflower formed the second group. Canudo de pito and castor seed meals and the cakes of cottonseed, licuri and jatropha I and II formed the third group. The fourth group was composed by the cakes of crambe, palm kernel and peanut I. The fifth group was formed by peanut cake II, while macauba fruit cake formed the sixth group. The VfNFC and VfFC varied from 16.72 to 200.07 mL and from 53.09 to 242.12 mL, respectively. The mean kdFC and kdNFC values varied from 0.002 to 0.039% h-1and from 0.022 to 0.430% h-1, respectively. The mean lag and VfT varied from 0.0001 to 5.2029 hours and 136.94 to 301.44 mL, respectively. A number of the products exhibited the potential to replace soybean meal, especially the forage radish cake and cottonseed, crambe and sunflower meals.