This study was conducted to investigate the effect of two distinct enzyme preparations on nutrients' digestibility and growth performance of growing pigs fed diets based on corn, soya bean meal and Chinese double-low rapeseed meal (DLRM). The two enzyme preparations were Enzyme R, a preparation extracted from fermentation of a non-GMO fungus Penicillum funiculosum, developed for multi-grain and multi-animal species; and Enzyme P, a xylanase preparation from Trichoderma longibrachiatum, for pigs fed corn-based diets only. Both enzymes were tested at 0, 0.25 and 0.50 g/kg feed using 70 crossbred male pigs (Large Yorkshire x Landrace) in five dietary treatments and seven replicates in each treatment, for growth period from 27 to 68 kg live weight in 49 days. Results showed that the supplementation of both enzymes (1) increased total-tract digestibility of dietary energy from 77.5% (control) to 81.4% (Enzyme R, p < 0.05) and 81.9% (Enzyme P, p < 0.05); of neutral detergent fibre from 41.0% (control) to 57.8% (Enzyme R, p < 0.05) and 60.0% (Enzyme P, p < 0.05); (2) improved average daily gain from 786 g (control) to 829 g (Enzyme R, p < 0.05) and 846 g (Enzyme P, p < 0.05); and numerical increases in feed intake from 1.96 kg/pig/day (control) to 2.01 (Enzyme R) and 2.00 (p > 0.05) and feed conversion ratio from 2.50 (control) to 2.42 (Enzyme R) and 2.36 (Enzyme P, p < 0.05); (3) there was a dose response but no significant differences were observed in enzyme efficacy between the two enzyme preparations. The present study demonstrated beneficial effects of applying xylanase-based enzymes to improve feeding values of pig diets based on corn, soya bean meal and DLRM.
Tulathromycin is a macrolide antimicrobial agent proposed for therapeutic use in treatment of porcine and bovine respiratory disease. In this study, the absolute bioavailability of tulathromycin solution was investigated in pigs. Eight pigs, with body weight of 20.5 ± 1.6 kg, were given a single dose of tulathromycin at 2.5 mg/kg oral (p.o.) and intravenous (i.v.) in a crossover design. The plasma concentrations of tulathromycin and its metabolite were determined by LC-MS/MS method, and the pharmacokinetic parameters of tulathromycin were calculated by noncompartmental analysis. After p.o. administration, the maximum plasma concentration (C(max) ) was 0.20 ± 0.05 μg/mL at 3.75 ± 0.71 h. The terminal half-life (t(1/2λz) ) in plasma was 78.7 ± 6.75 h, and plasma clearance (Cl/F) was 1.14 ± 0.28 L/h/kg. After i.v. injection, plasma clearance (Cl) was 0.580 ± 0.170 L/h/kg, the volume of distribution (Vz) was 64.3 ± 21.2 L/kg, and the t(1/2λz) was 76.5 ± 13.4 h. In conclusion, an analytical method for the quantification of tulathromycin and its metabolite in plasma in swine was developed and validated. Following p.o. administration to pigs at 2.5 mg/kg b.w., tulathromycin was rapidly absorbed and the systemic bioavailability was 51.1 ± 10.2.
To estimate the consumer exposure to olaquindox (OLA) residues in porcine edible tissues, a physiologically based pharmacokinetic (PBPK) model for methyl-3-quinoxaline-2-carboxylic acid (MQCA), the marker residue of OLA, was developed in pigs based on the assumptions of the flow-limited distribution, hepatic metabolism, and renal excretion. The model included separate compartments corresponding to blood, muscle, liver, kidney, adipose, and an extra compartment representing the remaining carcass. Physiological parameters were determined from literatures. Plasma protein binding, partition coefficients, and renal clearance for MQCA were determined in in vitro and in vivo studies. The metabolic conversion of OLA to MQCA was assumed as a simple, one-step process, and an apparent first-order rate constant (k) was employed to describe this metabolic process. The PBPK model was optimized and validated with plasma and tissue data from literatures and our study. Sensitivity analysis and Monte Carlo simulation were also implemented to estimate the influence of model parameters on the goodness of fit. When compared with the observed data, the PBPK model underestimated the MQCA level in all compartments at the early time points, whereas gave excellent predictions of MQCA concentration in porcine edible tissues at later time points. The correlation coefficients between the predicted and observed values were over 0.88. The consistency between the model predictions and the real residues of OLA in pigs proved the good applicability of our model in food safety risk assessment.
An in vitro and a feeding trial was conducted to investigate the effect of fibre-degrading enzymes A (xylanase + β-glucanase), B (xylanase) and C (xylanase + cellulase) on the nutritive value of broiler diets containing either hulled (22.5% and 23.5% for 4–21 days and 22–42 days of age, respectively) or dehulled (20% and 21.5%) Chinese double-low rapeseed meals (DLRM). Overall, in vitro digestibility of dry matter (DM) or neutral digestibility fibre (NDF) did not differ (p > 0.05) because of meal types; both crude protein (CP) and NDF digestibility was improved (p < 0.05) because of addition of enzymes B or C either to hulled or dehulled DLRM diets. Birds fed dehulled DLRM diets had a higher (p < 0.05) growth rate, feed efficiency and lower (p < 0.05) feed intake than those fed hulled DLRM diets during the overall phase. Enzyme C addition to dehulled DLRM diets resulted in improved (p < 0.05) growth rate and feed efficiency during 4–21 days of age. Enzymes A and B addition elicited a positive response in feed intake and weight gain (p < 0.05), respectively, but did not affect (p > 0.05) feed efficiency. It would appear that the nutritive value of broiler diets containing Chinese DLRM could be improved by appropriate xylanase-based enzymes. Responses of broilers to fibre-degrading enzymes could be highlighted by hull removal of fed DLRM.
Buffalo babesiosis represents a major problem for the livestock industry in China. The pathogen of this disease was isolated and identified as Babesia orientalis and subsequently propagated in vitro, using the microaerophilus stationary phase culture system. The aim of this study was to determine the efficacy of exoantigens derived from B. orientalis cultures to induce a protective immunity against challenge exposure to virulent organisms in laboratory and field. The results showed that exoantigens of B. orientalis could induce a high degree of protection against challenge with a virulent B. orientalis strain. The animals in the vaccinated group exhibited a slight decrease in haemoglobin levels and blood cell counts, whereas animals in the control group showed typical clinical symptoms and died between days 11 and 16 after challenge. In another approach, 82 buffaloes kept in B. orientalis-endemic areas were injected with exoantigens plus Freund's adjuvant in two doses at an interval of 2 weeks, one month before the endemic period. An additional 86 buffaloes served as unvaccinated controls. During the endemic period, the clinical signs of all buffaloes were monitored and the antibody response was investigated, using the latex agglutination test. During the endemic period, none of the vaccinated buffaloes showed clinical signs or died, whereas five control buffaloes showed clinical signs and two of them died. The mean antibody titre of vaccinated animals was higher than that of the control animals. These results showed that the culture-derived exoantigens of B. orientalis could be used as a vaccine to prevent buffalo babesiosis.
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