ObjectiveThe effects of particle size of processed barley grain, enzyme addition and microwave treatment on in vitro dry matter (DM) disappearance (DMD), gas production and fermentation pH were investigated for feedlot cattle.MethodsRumen fluid from four fistulated feedlot cattle fed a diet of 860 dry-rolled barley grain, 90 maize silage and 50 supplement g/kg DM was used as inoculum in 3 batch culture in vitro studies. In Experiment 1, dry-rolled barley and barley ground through a 1-, 2-, or 4-mm screen were used to obtain four substrates differing in particle size. In Experiment 2, cellulase enzyme (ENZ) from Acremonium cellulolyticus Y-94 was added to dry-rolled and ground barley (2-mm) at 0, 0.1, 0.5, 1, and 2 mg/g, while Experiment 3 examined the interactions between microwaving (0, 30, and 60 s microwaving) and ENZ addition (0, 1, and 2 mg/g) using dry-rolled barley and 2-mm ground barley.ResultsIn Experiment 1, decreasing particle size increased DMD and gas production, and decreased fermentation pH (p<0.01). The DMD (g/kg DM) of the dry-rolled barley after 24 h incubation was considerably lower (p<0.05) than that of the ground barley (119.1 dry-rolled barley versus 284.8 for 4-mm, 341.7 for 2-mm; and 358.6 for 1-mm). In Experiment 2, addition of ENZ to dry-rolled barley increased DMD (p<0.01) and tended to increase (p = 0.09) gas production and decreased (p<0.01) fermentation pH, but these variables were not affected by ENZ addition to ground barley. In Experiment 3, there were no interactions between microwaving and ENZ addition after microwaving for any of the variables. Microwaving had minimal effects (except decreased fermentation pH), but consistent with Experiment 2, ENZ addition increased (p<0.01) DMD and gas production, and decreased (p<0.05) fermentation pH of dry-rolled barley, but not ground barley.ConclusionWe conclude that cellulase enzymes can be used to increase the rumen disappearance of barley grain when it is coarsely processed as in the case of dry-rolled barley. However, microwaving of barley grain offered no further improvements in ruminal fermentation of barley grain.

This study was conducted to determine the effect of pelleting on in situ dry matter degradability of pelleted compound feed containing brown rice for dairy cows. Mash feed of the same composition was used as a control and the in situ study was conducted using three non-lactating Holstein steers fitted with a rumen cannula. The feeds contained 32.3% brown rice, 19.4% rapeseed meal, 11.4% wheat bran and 10.6% soybean meal (fresh weight basis). Except for moisture content, the chemical composition of the feed was not affected by pelleting. In situ dry matter disappearance of the feed increased from 0 to 2 h and after 72 h of incubation with pellet processing. Integration of the dry matter disappearance values over time revealed that degradability parameter a (soluble fraction) increased with pellet processing, whereas parameter b (potentially degradable fraction) decreased. Parameter c (fractional rate of degradation) and effective degradability (5% passage rate) were not affected by pellet processing. We concluded that pellet processing promotes rumen degradability at early incubation hours when the pelleted feed contains brown rice.

A fermented total mixed ration (TMR) was prepared by adding a vitamin premix containing vitamin A and enzyme to reed canarygrass roughage. The vitamin A levels were then determined after 30 days of fermentation at 20 or 30°C. The vitamin A contents had decreased in roughage fermented at both storage temperatures, and decreased further when an enzyme supplement was included. Because the majority of the added vitamin A was destroyed during fermentation and storage, the addition of vitamin A at the beginning of preparation of fermented TMR is not recommended.

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The present study aimed to explore the degradability of dry matter (DM) and crude protein (CP) of Jatropha curcas kernel meal with different detoxification treatments in the rumen. Moreover, the impacts of the Jatropha curcas kernel meal on rumen fermentation characteristics were also discussed. Jatropha curcas kernel meal adopted in current work was treated as: J. curcas kernel meal no treatment (JNT); J. curcas kernel meal extraction treatment (JET); J. curcas kernel meal heat treatment (JHT), and J. curcas kernel meal high pressure treatment (JPT). The in situ degradability of DM and CP of JHT was compared with those of soybean meal and rapeseed meal for cattle in Experiment I. The in vitro degradability and rumen fermentation characteristics of JNT, JET, JHT and JPT for wethers were investigated in Experiment II. Collectively, after treatments of JHT, JET and JPT, the phorbol ester (PE) content was decreased. In addition, the CP content was higher, of which the degradability was more than 90% after 72 h of in situ incubation. The Jatropha curcas kernel meal with different treatments had no negative effects on the rumen fermentation characteristics after in vitro incubation. It was concluded that Jatropha curcas kernel meal with detoxification treatments could be used as a potential protein feed.