Testing the efficacy of medium chain fatty acids against rabbit colibacillosis

Enteropathogenic Escherichia coli (EPEC) represents a major cause of lethal diarrhea in young mammals. Although the pathogenicity mechanisms of EPEC are now well understood, the intrinsic and environmental factors that control the expression of EPEC virulence remain largely unknown. In the rabbit, suckling reduces pups' sensitivity to EPEC infection. Hence, we have hypothesized that uncharacterized factors present in doe milk may mediate this protection. Medium chain fatty acids (MCFA), known to possess antimicrobial properties, are highly abundant in doe milk. We demonstrate that caprylic acid exhibits a clear bacteriostatic effect in vitro against the rabbit EPEC strain E22 (O103:H2:K-), in a dose-dependent manner. In vivo, the dietary inclusion of triglycerides of MCFA did not however reduce the sensitivity of young rabbits challenged with this EPEC strain. The mortality and fecal excretion of EPEC were not reduced, and the bacterial adhesion to ileum was not inhibited. Amount of MCFA reaching the ileal level might have been too low and/or their association to other milk antimicrobials may have been required to observe a positive effect on disease evolution in a context of a highly virulent challenge.     

日粮粗纤维品质对家兔生产性能的影响

降低日粮纤维水平和增加淀粉含量可提高生长速度 ,但木质素水平低的日粮会引起消化功能紊乱 ( Maite等 ,1 990 ;Blas等 ,1 994)。近期研究( Gidenne等 ,1 994和 1 996)结果表明 ,减少日粮纤维素和木质素 ( ADL )含量可提高家兔生产性能 ,但这些研究是在粗纤维水平变化的条件下进行的 ,这并不能准确解释粗纤维品质的影响 ,因此本研究的目的就是在粗纤维水平不变的条件下评定日粮中木质素与纤维素比率对生长家兔的生产性能、消化及健康的影响。本试验采用木质素与纤维素比率依次为 0 .8,0 .4和 0 .2的 3种日粮 (略写为 LC8、LC4和 LC2 )…     

Genetic variability of the resistance for three types of enteropathy in the growing rabbit

This paper describes the genetic variability for the resistance to three digestive stresses in the growing rabbit: after inoculation of coccidia (trial “coccidia”), with a fibre deficient diet (trial “FD”), and after experimental reproduction of epizootic rabbit enteropathy (trial “ERE”). Genetic variability was analysed from a sample of 48 sires, which produced the experimental young rabbits. These animals were examined on D0, D4, D11, D18, D25 and D32 after weaning (at 30 days old). Three clinical symptoms were checked: bloated abdomen, diarrhoea and mucus. Mortality and clinical symptoms were used to assess an individual response to each digestive stress. Two binary indexes were defined to describe this rabbit individual response. The first one (“Alive”) dealt with mortality. The second (“Tolerant”) dealt with mortality and morbidity. “Alive”, and “tolerant” percentages were low for the “coccidia” trial (61% and 23% respectively), high for the “FD” trial (75% and 36% respectively) and intermediate for the “ERE” trial (66% and 37% respectively). The sire effect was significant for each index in the “coccidia” and the “FD” trials. The sire effect was significant for the “tolerant” index in the “ERE” trial. Correlations between sire rankings for the two indexes of one trial were often significant. Correlations between sire rankings for indexes of “coccidia” and “FD” trials were weakly significant. Our results demonstrate that there is a genetic variability for the resistance to three different enteropathies.     

家兔饲养中消化问题的预防：低消化和可消化纤维的作用

日粮充足的纤维对预防生长兔消化问题是必需的，涉及到纤维种类，包括低消化纤维（木质纤维素）和可消化纤维（半纤维和果胶），一些富含可消化纤维的农副产品如麦麸和糟渣常用于家兔饲料。为此探讨了低消化和可消化纤维成分在断奶后生长兔消化健康方面的作用、不同的纤维类型包括在家兔饲料中常用的果胶、饲料纤维的一些特征，以及饲料中纤维成分的评估方法。