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Effects of enzymes and herbal extracts on in vitro fermentation kinetics of ruminant feeds

D. Colombatto^1,2*, A. D. Garciarena³, G. Lagos³, C. Lago⁴, F. Nahara^4
1University of Buenos Aires, Argentina; ²CONICET, Argentina; ³EEA Balcarce INTA, Argentina; ⁴Porfenc SRL, Argentina

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The message

Specific enzyme mixtures can positively affect alfalfa hay degradation in the rumen. The increases in degradation are attributable to the increased degradation of non-fibrous fractions.

Introduction

The use of fibrolytic enzymes and other fermentation modifiers such as herbal extracts (HE) is an emerging technology that shows promise in terms of enhancing animal performance. Moreover, they may offer an alternative to the use of antibiotics as growth promoters. The objective of this study was to examine the effects of two enzyme mixtures and a specific HE on alfalfa hay, corn silage and a total mixed ration (TMR) typical of a feedlot in Argentina.

Material and Methods

Approximately 0.5 g of pre-dried (milled to 2 mm) alfalfa hay, corn silage or a feedlot total mixed ration consisting of 70% corn grain, 20% corn silage, and 10% sunflower meal (DM basis) weighed in triplicate in 100-mL fermentation flasks (Table 1).

40 ml of anaerobic buffer and 10 ml ruminal fluid added to the fermentation flasks.

Fibrolytic enzymes supplied by Porfenc SRL (Martínez, Argentina), and added 16 h prior to inoculation with ruminal fluid.

Treatments: control (CON); two fibrolytic enzyme mixtures (denoted A and B, respectively) added at 25, 50 and 100 mg kg^-1 (DM basis) (0.5X, 1X, and 2X, respectively), and an herbal extract (HE) added at 750, 1500, and 3000 mg kg^-1 (DM basis).

Gas production (GP) kinetics determined at 2, 4, 6, 8, 10, 12, 15, 19, 24, 48 and 72 h post inoculation. DM and fiber degradability at 24 h also determined.

Experiment replicated on three occasions for GP, and in four occasions for degradability. MIXED Procedures of SAS used.

Table 1. Chemical composition of the feeds.

Results and Discussion

No effects on cumulative GP were detected (Table 2), save for a quadratic trend (P=0.09) towards higher GP of corn silage treated with Enzyme A . However, enzymes A and B cubically tended to increase GP at 2 h incubation time in alfalfa hay (Enzyme A: 15.2, 19.1, 16.3 y 18.1 mL/g OM for Control, 0.5x, 1x and 2x, respectively, P=0.07; Enzyme B: 15.2, 17.5, 16.1, 16.6 mL/g OM for Control, 0.5x, 1x and 2x, respectively, P=0.09, respectively), with Enzyme B linearly increasing (P=0.05) GP at 4 h in corn silage. HE did not affect (P>0.05) GP at anytime.

Enzyme A increased Alfalfa DM DEG at 1x, but decreased that of the feedlot ration when applied at 2x (Table 3).

Because fiber DEG remained unaffected, it is suggested that non-fibrous fractions were responsible for the differences in DM DEG with
Enzyme A.

Neither addition of Enzyme B nor HE affected (P>0.05) DM DEG (Table 4).

Table 3. Effects of Enzyme A on 24 h DM (g/kg) of

ruminant feeds

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Table 4. Effects of Enzyme B or Herbal extract (HE) on 24 h

DM (g/kg) of ruminant feeds.

Conclusions

Specific enzyme mixtures can positively affect degradation of selected ruminant feeds. These findings tend to confirm that responses are dose- and feed-specific.

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