No abstract

The objective of this study was to investigate the effects of 11 active compounds of essential oils (ACEO) on rumen fermentation characteristics and methane production. Two trials were conducted. In trial 1, ACEO (eugenol, carvacrol, citral, limonene, 1,4-cineole, p-cymene, linalool, bornyl acetate, α-pinene, and β-pinene) at a dose of 1,000 μL/L were incubated for 24 h in diluted rumen fluid with a 70:30 forage:concentrate substrate (16.2% crude protein; 36.6% neutral detergent fiber). Three fistulated Holstein cows were used as donors of rumen fluid. The reduction in methane production was observed with nine ACEO (up to 86% reduction) compared with the control (p<0.05). Among these, only limonene, 1,4-cineole, bornyl acetate, and α-pinene did not inhibit volatile fatty acid (VFA) production, and only bornyl acetate produced less methane per mol of VFA compared with the control (p<0.05). In a subsequent trial, the effects on rumen fermentation and methane production of two concentrations (500 and 2,000 μL/L) of bornyl acetate, the most promising ACEO from the first trial, were evaluated using the same in vitro incubation method that was used in the first trial. In trial 2, monensin was used as a positive control. Both doses of bornyl acetate decreased (p<0.05) methane production and did not inhibit VFA production. Positive effects of bornyl acetate on methane and VFA production were more pronounced than the effects of monensin. These results confirm the ability of bornyl acetate to decrease methane production, which may help to improve the efficiency of energy use in the rumen.

No abstract

In an experiment with 45 neonatal male Holstein calves, effects of yeast cultures Yea-Sacc^® 1026 (SC) containing <I>Saccharomyces cerevisiae</I> (strain 1026) and Vitex (KF) containing <I>Kluyveromyces fragilis</I> (strain Jürgensen) on rumen fermentation characteristics were determined. From day 4 to day 56 of age, the calves were allocated to one of the three dietary treatments (Control, SC, and KF) of 15 animals each, placed in individual pens, and fed 4 l of whole milk twice daily and a basal concentrate mixture ad libitum as calf starter feeds. The control treatment was not supplemented with yeast culture. The yeast culture supplements Yea-Sacc^® 1026 and Vitex were top-dressed at 10 g/calf daily on the basal concentrate mixture of treatments SC and KF, respectively. At the end of the experiment (day 56), all calves were slaughtered and the rumen fluid was analysed. The administration of yeast cultures Yea-Sacc^®026 and Vitex to calves did not affect final body weight (BW), BW gain, dry matter intake, feed conversion ratio, ruminal pH, lactic acid concentration and the molar proportion of propionic acid, but it decreased (<I>P</I> < 0.05) the total volatile fatty acid concentration and the molar proportion of butyric acid, and increased (<I>P</I> < 0.05) the molar proportion of acetic acid and the acetate to propionate ratio. In addition, the microbial cellulolytic activity was higher in calves that received both yeast cultures compared to the control treatment. The results of this study suggest that the ruminal fermentation was more stable in calves receiving yeast culture supplements.

No abstract

Lucerne (Medicago sativa L. var. Palava), harvested at four successive dates over a 30-day period, was evaluated for chemical composition (dry matter, organic matter, crude protein, ether extract, crude fibre, nitrogen-free extract, neutral detergent fibre, acid detergent fibre, acid detergent lignin), amino acid contents and intestinal digestibility in dairy cows. Dry matter (r = 0.78), organic matter (r = 0.95), crude fibre (r = 0.91), neutral detergent fibre (r = 0.94), acid detergent fibre (r = 0.79) and acid detergent lignin (r = 0.48) presented positive linear correlation coefficients (r) with growth stage, whereas crude protein (r = -0.96), ether extract (r = -0.86) and nitrogen-free extract (r = -0.70) showed negative relationships. Total essential amino acid content decreased (r = -0.94) from 84.1 to 55.3 g/kg of dry matter with maturity, with r-values higher than -0.90 obtained between growth stage and contents of lysine, methionine, threonine and valine. With the exception of tyrosine (r = -0.68), r-values between growth stage and individual non-essential amino acids were all higher than -0.90. Total amino acid (r = -0.98) and nitrogen (r = -0.99) contents presented comparable tendencies with successive sampling times. Whereas no definite trends were detected for the amino acid composition of rumen incubated (16 hours) lucerne samples, the intestinal digestibility of total essential (r = -0.78), total non-essential (r = -0.58) and total (r = -0.69) amino acids as well as nitrogen (r = -0.99) decreased with growth. However, due to a small sample size (n = 4), most linear relationships between constituents and growth stage were insignificant. It can be concluded that, although limited in the sample size, this report presents information on the decrease in amino acid contents and intestinal amino acid digestibility as growth proceeds in lucerne (var. Palava) produced in the Czech Republic, which could be utilized in the feeding of ruminants.

The main aim of this study was to investigate experimentally the effect of different composition of non-structural carbohydrates (NFC) in prepartum feed rations administered to high-yielding dairy cows at a high concentration of NFC in the diet on dry matter intake both before and after parturition and on subsequent milk performance, body condition and physiological traits of rumen fluid and blood. Thirty-six high-yielding dairy cows were allocated into one of the three well-balanced groups (K, O, and C), and each group received a different feeding rations. Feeding rations differed in non-structural carbohydrate (NFC) structure. The "K" (control) group received a feeding ration with NFC in the form of maize starch in particular, while the feeding rations of the other two (experimental) groups contained either (besides maize starch) saccharose from dried sugar beet (the "O" group) or a dominant amount of NFC was in the form of saccharose (the "C" group). After calving, all dairy cows were given the same feeding ration from the first day after parturition. The experiment was conducted for 21 days before and 50 days after calving. FR in the form of total mixed ration was offered ad libitum. Dry matter intake, milk performance, body condition, live weight, and blood and rumen parameters were recorded for the duration of the experiment. Average daily dry matter intake before calving was highest in the "K" group (14.32 kg per head). Differences among groups were statistically significant (P &lt; 0.05). Prepartum dry matter consumption dropped as the rate of saccharose in the diet of cows increased. Dry matter consumption levelled off after calving. Milk yield was also highest in the "K" group (43.71 kg/head/day), but fatness of milk and thus the production of fat corrected milk were lowest in this group. The highest milk fat content (4.10%) and fat corrected milk production (44.03 kg/head/day) were recorded in the "C" group, whereas the highest milk protein concentration was found in the milk of the "O" group. The composition of NFC affected dry matter intake before parturition, but these concentrations did not significantly affect dry matter intake, milk yield, milk composition, live weight, body condition or blood serum and rumen fluid parameters after calving

The objective of this study was to determine the effects of geraniol and camphene at three dosages (300, 600, and 900 mg l-1) on rumen microbial fermentation and methane emission in in vitro batch culture of rumen fluid supplied with a 60 : 40 forage : concentrate substrate (16.2% crude protein, 33.1% neutral detergent fibre). The ionophore antibiotic monensin (8 mg/l) was used as positive control. Compared to control, geraniol significantly (P < 0.05) reduced methane production with increasing doses, with reductions by 10.2, 66.9, and 97.9%. However, total volatile fatty acids (VFA) production and in vitro dry matter digestibility were also reduced (P < 0.05) by all doses of geraniol. Camphene demonstrated weak and unpromising effects on rumen fermentation. Camphene did not decrease (P > 0.05) methane production and slightly decreased (P < 0.05) VFA production. Due to the strong antimethanogenic effect of geraniol a careful selection of dose and combination with other antimethanogenic compounds may be effective in mitigating methane emission from ruminants. However, if a reduction in total VFA production and dry matter digestibility persisted in vivo, geraniol would have a negative effect on animal productivity.