The inhibitory effect of four trace elements on production of volatile fatty acids (VFA) and lactate was evaluated in cultures of rumen contents containing lead, mercury, cadmium and arsenic at 50, 100 and 250 μg/ml. The production of VFA in cultures containing Pb2+, Hg2+, Cd2+ and As5+ at 50 μg/ml was decreased by 15.9, 40.0, 29.1 and 35.6%, respectively. The effect of trace elements on molar profile of VFA was variable, which suggests a different toxic effect of elements tested on different groups of rumen microorganisms. Increasing concentrations of Pb2+ in rumen cultures decreased molar proportion of acetate and increased that of butyrate, whereas Hg2+ and Cd2 increased molar percentages of acetate and decreased butyrate. Lactate concentration in cultures containing Hg2+ increased in a dose-dependent manner from 3.10 to 9.20 μmol/ml. Effects of other trace elements on lactate production were not consistent.
Carotenoids are present in ingredients of feed for poultry. Their content can be further increased by supplementation of feed mixtures with synthetic or natural carotenoids. The present paper recapitulates knowledge on the use of carotenoids in broiler chickens and laying hens, and deals with synthetic or natural carotenoids derived from plants. The review describes effects of carotenoids on productive performance, oxidative stability of poultry products, colouring of yolks and accumulation of carotenoids in yolks. There are several alternatives to synthetic carotenoids which are usable in poultry diets and satisfy the interest of consumers in poultry products free of undesirable side effects.
Vannaphone Putthana, Milan Marounek, Natalie Brenova, Jakub Mrazek and Daniela Lukesova
Cronobacter spp. (formerly Enterobacter sakazakii) has been isolated from a wide range of environmental and several food sources. Cronobacter spp. is an opportunistic pathogen causing serious infection in infants, particularly neonates. The aim of this study was to isolate and characterize Cronobacter spp. from food sources (infant food, herbs and spices and vegetables) and from environmental sources as dust from vacuum cleaners. Isolation of Cronobacter spp. was performed on selective chromogenic agars, fi rstly using commercial ESIA agar and thereafter on Kim and Rhee-KR agar described in the literature. Phenotypic characteristics were obtained by commercial miniaturized biochemical ENTEROTEST 24 kits and the fi nal confi rmation of isolated strains was performed by molecular techniques (PCR, PCR - DGGE analysis, and 16S rDNA sequencing). Altogether, 99 samples were analyzed (47 samples of foods and 52 samples of dust). In total, 43 isolates of presumptive Cronobacter spp. were initially identifi ed, however, only 22 isolates (51%) were identifi ed as Cronobacter spp. with high identity scores (75-99%). The occurrence of presumptive cronobacters in environmental samples was signifi cantly higher than in samples of food (18 out of 52 vs. 4 out of 47; P = 0.003). No cronobacters were found in 17 samples of infant food, 3 isolates originated from herbs and spices, 1 isolate from spinach and 18 isolates from samples of dust (households, restaurants, dormitory rooms). It can be concluded that Cronobacter spp. is a ubiquitous pathogen contaminating food and environment. Cronobacter spp. could be well identifi ed by means of ENTERO24 test kits with high probability. Both phenotypic and genotypic methodology could be used for identifi cation of Cronobacter spp. and they can be combined for reliable identifi cation.