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1.
Improvement of feed efficiency in pigs has been achieved essentially by increasing lean growth rate, which resulted in lower feed intake (FI). The objective was to evaluate the impact of strategies for improving feed efficiency on the dynamics of FI and growth in growing pigs to revisit nutrient recommendations and strategies for feed efficiency improvement. In 2010, three BWs, at 35±2, 63±9 and 107±7 kg, and daily FI during this period were recorded in three French test stations on 379 Large White and 327 French Landrace from maternal pig populations and 215 Large White from a sire population. Individual growth and FI model parameters were obtained with the InraPorcR software and individual nutrient requirements were computed. The model parameters were explored according to feed efficiency as measured by residual feed intake (RFI) or feed conversion ratio (FCR). Animals were separated in groups of better feed efficiency (RFI or FCR), medium feed efficiency and poor feed efficiency. Second, genetic relationships between feed efficiency and model parameters were estimated. Despite similar average daily gains (ADG) during the test for all RFI groups, RFI pigs had a lower initial growth rate and a higher final growth rate compared with other pigs. The same initial growth rate was found for all FCR groups, but FCR pigs had significantly higher final growth rates than other pigs, resulting in significantly different ADG. Dynamic of FI also differed between RFI or FCR groups. The calculated digestible lysine requirements, expressed in g/MJ net energy (NE), showed the same trends for RFI or FCR groups: the average requirements for the 25% most efficient animals were 13% higher than that of the 25% least efficient animals during the whole test, reaching 0.90 to 0.95 g/MJ NE at the beginning of the test, which is slightly greater than usual feed recommendations for growing pigs. Model parameters were moderately heritable (0.30±0.13 to 0.56±0.13), except for the precocity of growth (0.06±0.08). The parameter representing the quantity of feed at 50 kg BW showed a relatively high genetic correlation with RFI (0.49±0.14), and average protein deposition between 35 and 110 kg had the highest correlation with FCR (−0.76±0.08). Thus, growth and FI dynamics may be envisaged as breeding tools to improve feed efficiency. Furthermore, improvement of feed efficiency should be envisaged jointly with new feeding strategies.  相似文献   
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Isothiocyanates (ITCs) are one of several hydrolysis products of glucosinolates, plant secondary metabolites that are substrates for the thioglucohydrolase myrosinase. Recent pursuits toward the development of synthetic non-natural ITCs have consequently led to an exploration of generating these compounds from non-natural glucosinolate precursors. Evaluation of the myrosinase-dependent conversion of select non-natural glucosinolates to non-natural ITCs cannot be accomplished using established ultraviolet–visible (UV–Vis) spectroscopic methods. To overcome this limitation, an alternative high-performance liquid chromatography (HPLC)-based analytical approach was developed where initial reaction velocities were generated from nonlinear reaction progress curves. Validation of this HPLC method was accomplished through parallel evaluation of three glucosinolates with UV–Vis methodology. The results of this study demonstrate that kinetic data are consistent between both analytical methods and that the tested glucosinolates respond similarly to both Michaelis–Menten and specific activity analyses. Consequently, this work resulted in the complete kinetic characterization of three glucosinolates with Sinapis alba myrosinase, with results that were consistent with previous reports.  相似文献   
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Mortality statistics for 25 populations of the larger Old World monkeys (members of the subfamily Cercopithecinae) were evaluated with a competing hazard model of mortality. The best eight of these life tables were combined to generate a standard model life table representative of the mortality patterns of these primates. Two applications of the standard model to smooth, graduate, and compare life tables based on limited and defective data are presented.  相似文献   
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Influence curves of estimators for directional data   总被引:1,自引:0,他引:1  
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BackgroundAmomum villosum Lour., (Zingiberaceae) an herbaceous plant in the ginger family, has been used to treat various diseases. In a single-blind, randomized, crossover study, we assessed the postprandial blood insulin and blood glucose responses in healthy subjects (n = 40) after the Amomum villosum water extract (AVE) (5 g/person) or a placebo (5 g/person) consumption.MethodsDuring each treatment course, the healthy subject consumed a regular late afternoon meal, followed by fasting for 12 h, and arrived at the clinical study center the next morning. Blood insulin and blood glucose levels were assessed at 0, 30, 60, 90, and 120 min after AVE consumption. Between each treatment, the subjects accomplished one week of a washout period.ResultsThe AVE intake demonstrated a significant (67.26%) decline in postprandial blood glucose AUC0–120 min (incremental area under the curve from 0 to 120 min) versus the placebo (P = 0.011). Furthermore, AVE reduced postprandial blood insulin AUC0–120 min by 59.95% compared to the placebo group (P < 0.003), supporting the blood glucose results.ConclusionThis study revealed that AVE consumption significantly reduced postprandial insulin and glucose levels in healthy individuals, due in part to inhibition of α-glucosidase, and glucose transport.  相似文献   
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The mutagenicity of 7-bromomethylbenz[a]anthracene, a reactive arylalkylating carcinogen, was investigated in several strains of E. coli WP2, using reversion from tryptophan auxotrophy (ochre trpE locus) as a measure of induced mutation.WP2, the wild-type with respect to DNA repair, was more resistant to the cytotoxic effects of 7-bromomethylbenz[a]anthracene than WP2uvrA, WP2exrA, or WP2uvrAexrA, the D37 doses of carcinogen being 22, 5, 8, and 1 μg/ml respectively. Mutagenesis in WP2 was observed only at doses in excess of the DQ, whereas in WP2uvrA mutation was linearly related to dose throughout the range studies. No mutation was detectable in WP2exrA or WP2uvrAexrA even at doses which resulted in 95% and 99.9% lethality respectively. It was concluded that an intact Exr function was an absolute requirement for the induction of mutation by 7-bromomethylbenz[a]anthracene and that excision-repair was very efficient in removing premutational lesios.The use of [3H]7-bromomethylbenz[a]anthracene at high specific radioactivity enabled the quantitation of mutation as a function of the extent of reaction of the mutagen with cellular macromolecules. Extent of reaction with DNA, RNA and protein was linearly related to dose, binding to DNA being 3 times that to RNA and 20 times that to protein. There was a linear relationship between binding and mutation in WP2uvrA and the effective target size for Exr-mediated mutation in this system was of the order of 0.04 nucleotides. Having established that the n umber of 7-bromomethylbenz[a]anthracene-induced mutants increased linearly with successive cell generations and, by use of T4 ochre427, that about 30% of the mutants scored were true revertants, it was estimated that the Exr pathway incorporates productive errors into the bacterial genome with a frequency of the order of 2.10?3.  相似文献   
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