Modificación de la fermentación microbiana ruminal mediante compuestos de aceites esenciales
This doctoral thesis was planned to test the potential of essential oils and their compounds as ruminal additives.
In the first study, eight dual flow continuous culture fermenters (1320 ml) were used in two replicated periods (8 d each) to study the effects of a specific blend of essential oil compounds (BEO, CRINA? RUMINANTS) on rumen microbial fermentation and nutrient flow. Treatments were arranged in a 2 x 2 factorial design. Main factors were type of diet (10 to 90 vs 60 to 40 forage to concentrate ratios) and the addition of BEO (0 vs 1.5 mg/l of BEO). There were no effects of BEO on DM, OM, NDF, ADF and CP digestion. The use of BEO increased the concentration of total VFA (122.8 vs 116.2 mM) without affecting individual VFA proportions or N metabolism.
The second experiment was designed to study the effect of dose of BEO and adaptation time to the addition of BEO on N metabolism of rumen microorganisms. The second study consisted in several tests. In the first, eight dual flow continuous culture fermenters (1320 ml) were used in two periods (6 d of adaptation and 3 d of sampling) to study the effects of increasing doses of a specific blend of essential oils (BEO, CRINA? RUMINANTS) on rumen microbial fermentation. Fermenters were fed with the same high forage ration of the first study and the sampling protocol and processing were identical. Treatments were: CTR (no BEO), D5 (5 mg/l of BEO), D50 (50 mg/l of BEO) and D500 (500 mg/l of BEO). In the second experiment, eight sheep (average body weight of 57 kg) were used to study the effects of long term adaptation of rumen fluid to BEO on ruminal fermentation. Four sheep were assigned at random to the CTR treatment (no BEO) and four sheep were adapted to BEO (110 mg/d of BEO) for four weeks (ADBEO). The addition of 5 mg BEO/l of rumen fluid in continuous culture increased total VFA concentration and acetate to propionate ratio after 6 d of fermentation, but changes in N metabolism were only apparent when using rumen fluid from sheep fed BEO for 28 d.
In the third study, several essential oil compounds were evaluated on rumen microbial fermentation. In the first experiment, the effects of 4 different doses (5, 50, 500, and 5000 mg/l) of five essential oil compounds were evaluated in in vitro 24 h batch culture of rumen fluid with two different diets: a 60 to 40 forage to concentrate diet (18% CP; 30% NDF) and a 10 to 90 forage to concentrate diet (16% CP; 25% NDF). Treatments were: control (CTR), eugenol (EUG), guaiacol, limonene, thymol (THY), and vanillin. In the second experiment, eight dual flow continuous culture fermenters (1320 ml) were used in three periods (6 d of adaptation and 3 d of sampling) to study the effects of THY and EUG on rumen microbial fermentation and nutrient flow. Treatments were: CTR (negative control), MON (positive control, 10 mg/l of monensin), T5 (5 mg/l of THY), T50 (50 mg/l of THY), T500 (500 mg/l of THY), E5, E50 and E500, and were randomly assigned to fermenters within periods. Most of these essential oil compounds demonstrated their antimicrobial activity decreasing total VFA concentration at high doses. However, EUG in batch fermentation and T5 in continuous culture modified VFA profile without decreasing total VFA concentration, and EUG decreased ammonia N concentration. Careful selection of these essential oils compounds may allow manipulation of rumen microbial fermentation.
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Advisor:Calsamiglia Blancafort, Sergio
School:Universitat Autónoma de Barcelona
Source Type:Master's Thesis
Keywords:458 departament de ciències animals i dels aliments
Date of Publication:05/31/2005