Influence of adding fibrolytic enzymes on the ruminal fermentation of date palm by-products

In vitro study on the effects of exogenic fibrolytic enzymes produced from <i>Trichoderma longibrachiatum</i> on ruminal degradation of olive mill waste

Olive mill waste is low-quality feed and rarely used in ruminant nutrition because of its high lignocellulose content, the existence of anti-nutritional factors such as total polyphenol and condensed tannin, and low protein contents. This in vitro research was conducted to valorize this waste (crude olive cake, extracted olive cake, and olive leaves) using an exogenous fibrolytic enzyme produced from Trichoderma longibrachiatum in ruminal nutrition. The enzymatic activity of this additive was 1161 units of endoglucanase per millilitre, 113 units of exoglucanase per millilitre, and 2267 units of xylanases per millilitre. This treatment was applied by spraying substrates with four doses: 0 (control), 1 (low), 2 (medium), and 4µLg-1µLg-1 (high) of dry matter olive mill waste in an air-conditioned room at 26 ∘C for 12 h before in vitro incubation.

For the crude olive cake, this additive at high doses increased degradation of 14 % of cellulose and 8 % of hemicellulose compared with the control at 12 h before the in vitro incubation. Consequently, it increased dry matter solubility and reduced sugars at this period compared to the control. Upon ruminal incubation, the high dose of exogenous fibrolytic enzyme increased the gas production from the immediately soluble fraction and insoluble fraction, the rate of gas production for the insoluble fraction, the dry matter degradability by 26 %, the organic matter degradability by 24 %, the metabolizable energy value by 28 %, and the microbial crude protein production by 24 % compared with the control. For olive leaves, an exogenous fibrolytic enzyme at medium dosage can also hydrolyse the hemicellulose compound, release fewer sugars, and increase dry matter solubility compared with the control at 12 h before the in vitro incubation.

Upon in vitro incubation, the medium dose increased the gas production from immediately soluble and insoluble fractions, the rate of gas production for the insoluble fraction, the dry matter degradability by 13 %, the organic matter degradability by 11 %, the metabolizable energy value by 12 %, and the microbial crude protein production by 12 % compared with the control. However, the highest dose altered the gas production from insoluble fractions and decreased microbial crude protein production by 6 % compared with the control. Under the same conditions, an exogenous fibrolytic enzyme applied to extracted olive cake did not produce any effect in the chemical composition and nutritional value. These results showed clearly that effectiveness of exogenous fibrolytic enzyme varied with incubated waste. Increasing the nutritional value of crude olive cake and olive leaves using an exogenous fibrolytic enzyme can encourage breeders to use this waste as feed at a low cost in animal nutrition. This valorization of waste is a good solution to reduce pollution of soils and groundwater caused by throwing out this polluted waste into the environment.

Effect of alkaline and sonication pretreatments on the rumen degradability of date palm seeds

The main objective of this research was to evaluate the effects of chemical treatment and sonication (ultrasound) processing on the fiber composition and rumen degradability of date palm seeds (DPS). In the first trial, the effects of incubation or sonication in 4% sodium hydroxide (NaOH) on DPS fiber content and ruminal degradability were evaluated. Relative to untreated seeds, the ruminal degradability of DPS neutral detergent fiber (NDF) and organic matter (OM) increased (P < 0.05) for the treated seeds and were highest (P < 0.05) for the sonicated seeds. Relative to untreated seeds, the hemicellulose and lignin content were lower (P < 0.05) for the sonicated seeds, while the cellulose content was higher (P < 0.05) for the incubated seeds. In the second trial, the effects of subjecting DPS to different sonication times (5, 10, 20, and 30 min) were evaluated. The degradability of seeds' NDF and OM were greater (P < 0.05) for the sonicated than unsonicated seeds. The highest NDF degradability was seen after 30 min sonication, whereas the OM degradability was not affected by sonication time (P > 0.05). In the third trial, the effects of subjecting DPS to sonication in different NaOH solutions (1%, 2%, 4% NaOH) were evaluated. Relative to untreated seeds, the rumen degradability of seeds' NDF and OM increased with all NaOH concentrations but was highest (P < 0.05) with the 4% NaOH. In conclusion, our results showed that treating DPS with 4% NaOH increased the seeds' ruminal degradability, and subjecting DPS to sonication further improved their degradability in the rumen.