1,721,013 research outputs found
Effect of extra dietary lysine in Ascaridia galli-infected grower layers
No full textThe hypothesis examined in this study was that extra dietary lysine (Lys) above the recommended standard exerts beneficial effects on the defence reactions, growth performance and nutrient utilization in Ascaridia galli-infected chickens. Therefore, 1-day-old female Lohmann Selected Leghorn chickens were at first fed standard Lys diet (8.5g Lys/kg DM). At 4 weeks of age, the birds were allocated to groups 1 and 3, both being continued on standard Lys diet, whereas birds in groups 2 and 4 were switched to extra Lys diet (10.5g Lys/kg DM). Birds in groups 3 and 4 were additionally infected at this age (4 weeks) with 250 embryonated eggs of A. galli. All the birds were slaughtered 7-week-post-infection (p.i.) at an age of 11 weeks. Infected birds on standard Lys diet consumed more feed and reached a similar level of Lys intake as birds on extra Lys diet 7-week-p.i. Utilization of feed, crude protein, and Lys for body weight (BW) gain was adversely affected in infected birds on standard Lys diet (P 0.05). Extra Lys diet led to higher final BW in uninfected and infected birds (P < 0.05). It is concluded that extra Lys above the normal recommended standard supports the defence reactions and compensates the negative effect of infection on growth performance and nutrient utilization in A. galli-infected birds. (C) 2010 Elsevier B.V. All rights reserved
Association study in naturally infected helminth layers shows evidence for influence of interferon-gamma gene variants on <it>Ascaridia galli </it>worm burden
Full text linkAbstract Single nucleotide polymorphisms (SNPs) in the genes for interleukin-4, -13 and interferon-gamma, and 21 additional SNPs which previously had been significantly associated with immune traits in the chicken, were genotyped in white and brown layer hens and analyzed for their association with helminth burden following natural infections. A nucleotide substitution located upstream of the promoter of the interferon-gamma gene was significantly associated with the log transformed number of Ascaridia galli in the brown layer line (genotype CC: 6.4 ± 1.0 worms; genotype CT: 11.7 ± 2.2 worms). Therefore, IFNG seems to be a promising candidate gene for further studies on helminth resistance in the chicken.</p
Helminth infections in laying hens kept in organic free range systems in Germany
No full textThis study describes the spectrum and intensity of helminth infections in laying hens kept in organic production systems in Germany. A total of 740 laying hens from 18 organic free range farms were collected between 2007 and 2010. The hens were sacrificed and the gastrointestinal tracts were examined for the presence and intensity of helminth infections with standard parasitological methods. Three nematode (Ascaridia galli, Heterakis gallinarum, Capillaria spp) and four cestode (Raillietina cesticillus, Hymenolepis cantaniana, Hymenolepis carioca, Choanotaenia infundibulum) species were found. Almost all hens (99.6%, N=737) harboured at least one helminth species. Average worm burden per hen was 218.4 (SD=218.3) worms. The most prevalent species were the nematodes Heterakis gallinarum (98%) followed by Ascaridia gall (88%) and Capillaria spp. (75.3%). The overall prevalence of the cestodes was 24.9%. Total worm burden was significantly higher during the summer season when compared with animals slaughtered during winter season (254 vs. 191, P<0.0001). The most dominant helminth species was Heterakis gallinarum averaging 190 (SE = 9.8) worms per hen in the summer and 129 (SE = 8.7) in the winter season (P<0.0001). Average Ascaridia gall burden was 25 (SE = 2.0) in summer and 26 (SE = 1.7) in winter (P=0.1160). Risk of infection with any of the nematodes was 50% higher in summer compared to winter (Psi = 1.49, P<0.0319). Probability of infection with any of the tapeworm species was 3.5 times higher in summer than in winter (P<0.0001). It can be concluded that the vast majority of hens are subclinically infected with at least one helminth species. The prevalence as well as intensity of the helminth infections, particularly with tapeworms, considerably increases in summer. The results indicate that it is essential to adopt alternative control strategies in order to lower infection risk in organic production systems which are gaining popularity. (C) 2011 Elsevier B.V. All rights reserved
Precision, repeatability and representative ability of faecal egg counts in Heterakis gallinarum infected chickens (vol 183, pg 87, 2011)
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Precision, repeatability and representative ability of faecal egg counts in Heterakis gallinarum infected chickens
Full text linkThis study investigated whether a precise and repeatable quantification of Heterakis gallinarum egg excretion, which considerably reflects the actual worm burdens, can be achieved based on collection of the daily total amount of faeces from chickens. Three-week-old birds (N = 64) were infected with 200 embryonated eggs of H. gallinarum, and placed into individual cages 3 wk after infection for 5 wk to collect daily faeces (N = 2240). The total daily faeces was mixed and a randomly taken sample per bird was analyzed to estimate the numbers of eggs per gram of faeces (EPG) and total number of eggs excreted within 24h (EPD). A total of 235 daily faecal collections were randomly selected and further examined to determine between and within sample variations of EPG counts as a measure of precision. For this, two random faecal samples were taken from the daily produced faeces by a bird, and the EPG was determined for each of the samples (EPG1 and EPG2). The second faecal sample was analyzed once more to determine a parallel EPG2 count (EPG2a) of the suspended sample. Precision of an EPG count was defined as its relative closeness to the average of two EPG counts using a relative asymmetry index (Index(EPG)). At an age of 11 wk, i.e. 8 wk p.i. the birds were slaughtered and their worm burdens were determined. There were no significant differences between EPG1 and EPG2 (P = 0.764) nor between EPG2 and EPG2a (P = 0.700), suggesting that the differences between or within the samples were not different from zero. Correlations between EPG counts, as between and within sample coherences, were r = 0.85 and r = 0.86, respectively. Precision of EPG counts, as measured by Index(EPG), was not influenced by consistency (P = 0.870) and total amount of faeces (P = 0.088). However, concentration of eggs in faeces (mean EPG) had a significant effect on the precision of the EPG counts (P = 0.70; P < 0.05) in a few days after the nematode excreted eggs and predominantly remained so for the rest of the sampling period. It is concluded that mixing daily total faeces provides samples with random homogenous distribution of H. gallinarum eggs. Precision of the EPG counts increases as the egg concentration in faecal sample increases. Egg excretion of H. gallinarum, quantified either as EPG or EPD, is highly repeatable and closely correlated with the actual worm burden of birds starting as early as in 5th wk of infection. (C) 2011 Elsevier B.V. All rights reserved
Genetic resistance to natural helminth infections in two chicken layer lines
No full textGroups of Lohmann Brown (LB) and Lohmann Selected Leghorn (LSL) hens were reared under helminth-free conditions and kept afterwards together in a free range system. Mortality rate, body weight development, laying performance and faecal egg counts (FEC) were recorded during a 12 month laying period. At the end of the laying period, 246 LSL and 197 LB hens were necropsied and worms counted following the World Association for the Advancement of Veterinary Parasitology (W.A.A.V.P.) guidelines. In addition adult Heterakis gallinarum and Ascaridia galli were sexed and measured for length. Significant (P 0.05) different between the genotypes. There was no significant phenotypic correlation between body weight and worm burden in LSL, whereas it was the case in LB (r = 0.17, P < 0.05). Based on the estimated heritabilities it is possible to select for helminth resistance in both genotypes. (C) 2010 Elsevier B.V. All rights reserved
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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