-We have amplified, cloned and sequenced (part of) the open reading frame of the S1 segment encoding the σ C protein of avian reoviruses isolated from chickens with different disease conditions in Germany and The Netherlands during 1980 up to 2000. These avian reoviruses were analysed phylogenetically and compared with sequences of avian reoviruses in the Genbank database. The avian reoviruses could be grouped in 5 different genotyping clusters and this classification was identical when the sequences were compared of the 5' end, the 3' end or the whole open reading frame of the σ C protein. Therefore sequencing of either part of the gene encoding the σ C protein seems to be reliable for classification. We were unable to identify a correlation between σ C sequences of the avian reoviruses and the disease condition they were isolated from. The sequences found in The Netherlands and in Germany are, like those in Taiwan, more dispersed than the known avian reovirus σ C sequences in the USA and Australia. We did not establish temporal or geographic differences in the avian reoviruses studied. avian reovirus / malabsorption syndrome / tenosynovitis / σ C gene / genotype

The impact of growth curve ( GC ) and dietary energy-to-protein ratio on productive performance of broiler breeder females was investigated from 0 to 60 wk of age. One-day-old pullets (n = 1,536) were randomly allotted to 24 pens according to a 2 × 4 factorial arrangement, with 2 GC (standard growth curve = SGC or elevated growth curve = EGC , +15%) and 4 diets, differing in energy-to-protein ratio (96%, 100%, 104%, or 108% AME n ). Feed allocation per treatment was adapted weekly based on the desired GC, meaning that breeders fed the different diets within each GC were fed according to a paired-gain strategy. Linear and quadratic contrasts for energy-to-protein ratio for each GC were evaluated. Elevated growth curve breeders had an earlier sexual maturity (∆ = 4.1 d) than SGC breeders. Egg weight was higher for EGC breeders (∆ = 2.3 g) than for SGC breeders over the whole laying phase (22–60 wk). No differences between EGC and SGC breeders were observed on settable egg production. An increase in dietary energy-to-protein, at a similar BW, led to a linear increase in age at sexual maturity (β = 0.14 d/% AME n ). From 22 to 40 wk of age, an increase in dietary energy-to-protein ratio led to a linear decrease in egg weight (β = -0.06 g/% AME n ), regardless of GC. An interaction between GC and dietary energy-to-protein ratio was observed on settable egg production in this phase. An increase in dietary energy-to-protein ratio led to a linear decrease on settable egg production, which was more profound in EGC breeders (β = -0.70 eggs/% AME n ) than in SGC breeders (β = -0.19 eggs/% AME n ). From 41 to 60 wk of age, an interaction between GC and dietary energy-to-protein ratio was observed on egg weight. In the EGC, an increase in dietary energy-to-protein ratio led to a linear decrease in egg weight (β = -0.13 g/% AME n ), whereas in the SGC, a linear increase in egg weight was observed (β = 0.03 g/% AME n ). From 41 to 60 wk of age, no differences between diets were observed on settable egg production. It can be concluded that a higher GC of breeders has beneficial effects on egg weight, while maintaining settable egg production. Feeding breeders a lower dietary energy-to-protein ratio stimulated productive performance of broiler breeder hens, mainly during the first phase of lay. This effect was more profound when breeders were fed according to a higher GC.

In this study, the results are reported from a validation study of five commercially available enzymelinked immunosorbent assays (ELISAs) for the detection of antibodies against infectious bursal disease virus (IBDV), serotype 1. The specificity of the ELISAs varied from 63.8 to 100%. All ELISAs reached a sensitivity of 100% on sera between 14 and 21 days post-vaccination (d.p.v.) with two classical vaccines and a Delaware variant-E virus. Overall, most birds became positive between 8 and 11 d.p.v. As expected, the ELISA with the lowest specificity showed the highest sensitivity at 5 d.p.v. When the decrease in maternally derived antibodies against IBDV was measured, a highly significant correlation (P < 0.001) was found for all ELISAs and the virus neutralization test (VNT).

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