The objectives of the trial were to investigate the effects of supplementing vitamin E (VE) on nutrient digestion, nitrogen (N) retention and plasma parameters of beef cattle in feedlot. Four growing Simmental bulls, fed with a total mixed ration composed of corn silage and concentrate mixture as basal ration, were used as the experimental animals. Four levels of VE product, i.e. 0, 150, 300, 600 mg/head/d (equivalent to 0, 75, 150, 300 IU VE/head/d), were supplemented to the basal ration (VE content 38 IU/kg dry matter) in a 4×4 Latin square design as experimental treatments I, II, III and IV, respectively. Each experimental period lasted 15 days, of which the first 12 days were for pretreatment and the last 3 days for sampling. The results showed that supplementing VE did not affect the nutrient digestibility (p>0.05) whereas decreased the urinary N excretion (p<0.01), increased the N retention (p<0.05) and tended to increase the microbial N supply estimated based on the total urinary purine derivatives (p = 0.057). Supplementing VE increased the plasma concentrations of VE, glucose and triglycerol (TG) (p<0.05) and tended to increase the plasma concentration of total protein (p = 0.096) whereas did not affect the plasma antioxidant indices and other parameters (p>0.05). It was concluded that supplementing VE up to 300 IU/head/d did not affect the nutrient digestibility whereas supplementing VE at 150 or 300 IU/head/d increased the N retention and the plasma concentrations of VE and TG (p<0.05) of beef cattle.
The objectives of the trial were to study the effects of rare earth element (REE) lanthanum (La) on the in vitro rumen methane (CH4 ) and volatile fatty acid (VFA) production and the microbial flora of feeds. Four feed mixtures with different levels of neutral detergent fibre (NDF), that is 20.0% (I), 31.0% (II), 41.9% (III) and 52.7% (IV), were formulated as substrates. Five levels of LaCl3 , that is 0, 0.4, 0.6, 0.8 and 1.0 mmol/kg dry matter (DM), were added to the feed mixtures, respectively, as experimental treatments in a two-factor 5 × 4 randomized design. The in vitro incubation lasted for 24 h. The results showed that supplementing LaCl3 increased the total gas (p < 0.001) production and tended to increase the total VFA production (p = 0.072) and decreased the CH4 production (p = 0.001) and the ratios of acetate/propionate (p = 0.019) and CH4 /total VFA (p < 0.001). Interactions between LaCl3 and NDF were significant in total gas production (p = 0.030) and tended to be significant in CH4 production (p = 0.071). Supplementing LaCl3 at the level of 0.8 mmol/g DM decreased the relative abundance of methanogens and protozoa in the total bacterial 16S rDNA analysed using the real-time PCR (p < 0.0001), increased F. succinogenes (p = 0.0003) and decreased R. flavefaciens (p < 0.0001) whereas did not affect R. albus and anaerobic fungi (p > 0.05). It was concluded that LaCl3 decreased the CH4 production without negatively affecting feed digestion through manipulating rumen microbial flora when feed mixtures with different levels of NDF were used as substrates.
ABSTRACT:Two in vitro trials were carried out to study the effects of supplementing vitamin E (V E ) on rumen fermentation. In Trial I, four levels of V E product (purity 50%), i.e. 0, 15, 30, and 60 mg/kg dry matter (DM) of feed (equivalent to 0, 7.5, 15, 30 IU V E /kg DM) were supplemented to a typical feed mixture, respectively, as experimental treatments. The gas test technique of Menke et al. (1979) was used to measure gas and volatile fatty acid (VFA) production. In Trial II, the in vitro incubation technique of Zhao and Lebzien (2000) was used to determine DM disappearance rate and utilizable crude protein (uCP). Four levels of V E , i.e. 0, 7.5, 15, 30 IU/kg DM were supplemented to the same feed mixture as in Trial I, respectively, as experimental treatments. The results showed that supplementing V E increased total gas production (P < 0.01) and tended to increase methane (CH 4 ) production (P = 0.087). Supplementing V E also increased total VFA (P < 0.05) and propionate (P < 0.05), tended to increase acetate production (P = 0.084), and significantly increased DM disappearance rate (P < 0.05) and uCP (P < 0.01). It was concluded that supplementing V E at 30 IU/kg DM under the conditions of present trials with 11.1 IU/kg DM in the feed mixture improved in vitro rumen fermentation of feed mixture. Further research is necessary to confirm the effects of supplementing V E using in vivo trials.
The present paper mainly investigates noise propagation in limited enclosed space with non-compact bodies. In view of the scattering effect induced by solid boundaries, tailored green’s function methods are used to study the noise propagation. Frequency-domain integral equation is presented to calculate scattered noise under impedance boundary condition in enclosed space. At first, the scattered noise of circular cylinder with solid boundary condition is calculated to verify the validity of the present algorithm. Secondly, the impedance boundary condition is executed on the cylinder wall. Furthermore, the impedance boundary conditions are carried out on the boundaries of enclosed space. Numerical results demonstrate that the total noise drastically reduces in some areas with impedance boundary, but increases in other areas. The phenomenon is related with the cylinder radius, the location of sound sources and the scattering effect. In practical engineering problems, the impedance boundary should be applied locally according to the configuration.
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