Due to the functional importance of bovine milk protein polymorphisms, their correct discrimination is of great interest both from a scientific and practical point of view. Nowadays a large number of commercial platfo...Due to the functional importance of bovine milk protein polymorphisms, their correct discrimination is of great interest both from a scientific and practical point of view. Nowadays a large number of commercial platforms are available for semiautomated or fully automated SNP geno-typing. However, in some cases the use of simple and rather cheap methods is an effective tool to be implemented within one’s own laboratory for the routine analysis of a specific SNP. The present paper describes two simple tests based on the bidirectional allele-specific polymerase chain reaction (BAS-PCR) developed for the identification of β-casein (CSN2) B and I genetic variants. The practical application of the two methods on a panel of 84 Italian Brown bulls and 100 Italian Friesian cows is also discussed, including the biological significance of the two genetic variants and the importance of taking their occurrence into account when linkage analyses are performed on milk functional properties. A combined system for analysing milk protein variants by isoelectrofocusing (IEF) and the BAS-PCR assay developed for CSN2*I is described.展开更多
Escherichia coli diarrhoea is a multifactorial condition which usually occurs during the post-weaning and is responsible for economic losses in pig production. One approach, to evaluate if substitute of antibiotic in ...Escherichia coli diarrhoea is a multifactorial condition which usually occurs during the post-weaning and is responsible for economic losses in pig production. One approach, to evaluate if substitute of antibiotic in vivo is effective in controlling postweaning diarrhea in the gastrointestinal tract ecosystem, is to use an appropriate disease model. However, there are still many criticisms related to the incidence and the severity of the diarrhoea in the experimental conditions. The aim of the study was to set up an Escherichia coli challenge model in order to induce a significant percentage of diarrhoea in weaned piglets for the evaluation of innovative compounds in vivo. A total of 35 piglets, weaned at 33±2 days were randomized into 3 groups: control (CG), infected 1 (IG1) and infected 2 (IG2). One day after arrival piglets of IG1 and IG2 were orally inoculated with 3.7 × 108 CFU of Escherichia coli O149. All piglets were fed a high protein ration for 3 days. Daily health status and faeces were recorded by a point scale individually. Challenge strains in faecal samples were evaluated by polymerase chain reaction, serotyping and biochemical identification. Diarrhoea was observed in 96.67% (58.6% severe;41.4% mild) of all infected piglets and occurred on average 1.3 days after the challenge. The CG group presented one piglet with a transient mild diarrhoea. The E. coli challenge significantly affected the consistency and color of faeces (P E. coli O149, mainly hemolytic (88%), was isolated in 56% of faecal samples and the 70% of piglets with severe diarrhoea shed E. coli O149 in the faeces. Zootechnical parameters did not show significant differences. The experimental conditions described in this study allowed to effectively induce diarrhoea in weaned piglets. In conclusion a multifactorial approach (infectious, nutritional and management) is necessary to reproduce in vivo diarrhea in piglets.展开更多
文摘Due to the functional importance of bovine milk protein polymorphisms, their correct discrimination is of great interest both from a scientific and practical point of view. Nowadays a large number of commercial platforms are available for semiautomated or fully automated SNP geno-typing. However, in some cases the use of simple and rather cheap methods is an effective tool to be implemented within one’s own laboratory for the routine analysis of a specific SNP. The present paper describes two simple tests based on the bidirectional allele-specific polymerase chain reaction (BAS-PCR) developed for the identification of β-casein (CSN2) B and I genetic variants. The practical application of the two methods on a panel of 84 Italian Brown bulls and 100 Italian Friesian cows is also discussed, including the biological significance of the two genetic variants and the importance of taking their occurrence into account when linkage analyses are performed on milk functional properties. A combined system for analysing milk protein variants by isoelectrofocusing (IEF) and the BAS-PCR assay developed for CSN2*I is described.
文摘Escherichia coli diarrhoea is a multifactorial condition which usually occurs during the post-weaning and is responsible for economic losses in pig production. One approach, to evaluate if substitute of antibiotic in vivo is effective in controlling postweaning diarrhea in the gastrointestinal tract ecosystem, is to use an appropriate disease model. However, there are still many criticisms related to the incidence and the severity of the diarrhoea in the experimental conditions. The aim of the study was to set up an Escherichia coli challenge model in order to induce a significant percentage of diarrhoea in weaned piglets for the evaluation of innovative compounds in vivo. A total of 35 piglets, weaned at 33±2 days were randomized into 3 groups: control (CG), infected 1 (IG1) and infected 2 (IG2). One day after arrival piglets of IG1 and IG2 were orally inoculated with 3.7 × 108 CFU of Escherichia coli O149. All piglets were fed a high protein ration for 3 days. Daily health status and faeces were recorded by a point scale individually. Challenge strains in faecal samples were evaluated by polymerase chain reaction, serotyping and biochemical identification. Diarrhoea was observed in 96.67% (58.6% severe;41.4% mild) of all infected piglets and occurred on average 1.3 days after the challenge. The CG group presented one piglet with a transient mild diarrhoea. The E. coli challenge significantly affected the consistency and color of faeces (P E. coli O149, mainly hemolytic (88%), was isolated in 56% of faecal samples and the 70% of piglets with severe diarrhoea shed E. coli O149 in the faeces. Zootechnical parameters did not show significant differences. The experimental conditions described in this study allowed to effectively induce diarrhoea in weaned piglets. In conclusion a multifactorial approach (infectious, nutritional and management) is necessary to reproduce in vivo diarrhea in piglets.
