Brood parasitism represents a unique mode of avian reproduction that requires a number of adaptations. For example, to reduce chances of puncture ejection of their eggs by small hosts, brood parasites may have been selected for laying eggs of unusually great structural strength. However, great structural strength of eggshells should hinder hatching. The goals of our study were to establish if chicks of the Common Cuckoo Cuculus canorus have more difficulty with hatching out of their strong eggs than chicks of species with eggs of similar size, and whether they possess any mechanisms facilitating hatching. To achieve these goals, we compared hatching pattern and selected body characteristics of chicks of the Common Cuckoo with those of another altricial species with eggs of a similar size, the Great Reed Warbler Acrocephalus arundinaceus. Although the rate of pecking was similar in the two species, the Common Cuckoo chicks started pecking earlier in relation to their emergence and consequently required more time and a greater cumulative number of pecks for breaking open their eggs than did young Great Reed Warblers. The two species also differed with respect to the pattern of opening their shells; in contrast to the warbler chicks, which enlarged the original pip circularly, the cuckoo chicks opened the egg by systematically creating a long narrow slit until they emerged. Finally, our study of hatched young revealed several differences; the Cuckoo hatchlings were significantly heavier, had a longer forearm, and their egg tooth was located significantly farther from the tip of the beak. The edge used for cutting through the shell was also significantly longer than that of hatchling Great Reed Warblers. To conclude, our data suggest that hatching is more difficult for a Cuckoo than for a Great Reed Warbler and that Cuckoos possess several mechanisms to overcome the problems of hatching from a structurally strong egg.

Blackcaps Sylvia atricapilla reject artificial cuckoo eggs, and their eggs vary little in appearance within clutches, whereas among clutches eggs vary considerably. Low variation within clutches facilitates discrimination of parasitic eggs, whereas high variation among clutches makes it harder for the cuckoo to mimic the eggs of a certain host species. These traits have most probably evolved as counteradaptations against brood parasitism by the common cuckoo Cuculus canorus, even though blackcaps are not regularly parasitised today. In this study, we investigated how fine-tuned the rejection of parasitic eggs is in this species by introducing three types of eggs into their nests: a real non-mimetic egg the approximate size of a cuckoo egg, an artificial mimetic egg the size of a cuckoo egg and a real conspecific egg. As the rejection frequency of both mimetic and non-mimetic artificial cuckoo eggs has been shown to be high in previous studies, the variation in rejection behaviour between individuals is low, indicating that most individuals within the population are able to reject parasitic eggs. Thus, we predict that (1) the intraclutch variation in egg appearance should be generally low in all individuals, and that (2) regarding conspecific eggs, rejection decisions should be highly dependent on the degree of mimicry between parasitic and host eggs. We found support for these predictions, which indicates that due to their highly sophisticated countermeasures against brood parasitism, blackcaps can probably be regarded as current winners of the arms race with the common cuckoo. Furthermore, the high and consistent rejection frequency of cuckoo eggs found throughout Europe for this species supports the spatial habitat structure hypothesis, which claims that woodland-nesting species breeding near trees, like blackcaps, presumably experienced a high level of parasitism throughout their range in the past and, therefore, their rejection behaviour, once evolved, spread rapidly to all populations.

ABSTRACT:The purpose of the present study was to assess the effect of kaolin feeding on health status, body weight gain (BWG), course of diarrhoeal infections caused by enterotoxigenic strains of Escherichia coli (ETEC) and the level of mycobacterial contamination in weaned piglets. The testing was performed in two experiments involving 40 weaned piglets at the age of 28 days. In the infection-free experiment, piglets were fed a diet without (C0) or with 1% content of kaolin (K0) for 20 days. Subsequently, all of them were fed the same diet without kaolin supplementation for 39 days. Identical diets were fed during the infection experiment, and moreover, both groups (CI and KI) were orally infected with ETEC (O141:F18ac, STa+) on Day 1 of experiment. The short-term feeding of kaolin to weaned piglets had a significant positive effect on their BWG. During the period of feeding the kaolin-containing diets, BWG in C0 and K0 were 0.20 and 0.29 kg, respectively (P < 0.05), and in CI and KI 0.13 and 0.19 kg, respectively (P < 0.05). There was no evidence of side effects to their health, neither was there any change in biochemical and haematological profiles. In the infection experiment, a protective effect of kaolin on the course of ETEC infection was evident. Colonization and shedding of ETEC by piglets fed the kaolin diet were milder and had a shorter duration in comparison with control piglets. The culture examination of pure kaolin and kaolin containing diets for mycobacteria were negative. Potentially pathogenic mycobacteria occurring in the environment were isolated from faeces and tissues of pigs. According to these results, supplementation of diets with 1% kaolin to prevent diarrhoea in piglets and to support their growth in the critical post-weaning period could be recommended.

ABSTRACT:Mycobacterium arupense is a non-tuberculous, potentially pathogenic species rarely isolated from humans. The aim of the study was to ascertain the spectrum of non-tuberculous mycobacteria within 271 sequenced mycobacterial isolates not belonging to M. tuberculosis and M. avium complexes. Isolates were collected between 2004 and 2009 in the Czech Republic and were examined within the framework of ecological studies carried out in animal populations infected with mycobacteria. A total of thirty-three mycobacterial species were identified. This report describes the isolation of M. arupense from the sputum of three human patients and seven different animal and environmental samples collected in the last six years in the Czech Republic: one isolate from leftover refrigerated organic dog food, two isolates from urine and clay collected from an okapi (Okapia johnstoni) and antelope bongo (Tragelaphus eurycerus) enclosure in a zoological garden, one isolate from the soil in an eagle's nest (Haliaeetus albicilla) band two isolates from two common vole (Microtus arvalis) livers from one cattle farm. All isolates were identified by biochemical tests, morphology and 16S rDNA sequencing. Also, retrospective screening for M. arupense occurrence within the collected isolates is presented.

ABSTRACT:The objective of this study was to determine the wildlife hosts of Mycobacterium avium subsp. paratuberculosis (MAP) in the Czech Republic. A total of 8 796 wildlife animals were examined by culture of faecal or tissue samples during the years [2002][2003][2004][2005][2006][2007]. MAP was isolated from 12 (0.5%) out of 2 296 red deer (Cervus elaphus), two (0.2%) out of 835 roe deer (Capreolus capreolus), 78 (5.7%) out of 1 381 fallow deer (Dama dama), 28 (3.2%)out of 866 mouflons (Ovis musimon), four (2.5%) out of 162 chamois (Rupicapra rupicapra) and from one (0.1%) out of 805 wild boar (Sus scrofa). MAP was not cultured from 82 badgers (Meles meles), 55 martens (Martes foina), one pine marten (Martes martes), 25 brown hares (Lepus europaeus), five rabbits (Oryctolagus cuniculus), nine European polecats (Mustela putorius), two steppe polecats (Mustela eversmannii), two American minks (Mustela vison), four raccoon dogs (Nyctereutes procyonoides) and four Eurasian otters (Lutra lutra). MAP was isolated from three (2.0%) out of 149 small terrestrial mammals: one (5.9%) out of 17 brown rats (Rattus norvegicus), one (1.7%) out of 59 common voles (Microtus arvalis) and one (2.6%) out of 39 lesser white-toothed shrews (Crocidura suaveolens). Culture examinations of 34 house mice (Mus musculus) and 2 113 pigeons (Columba livia f. domestica) were negative. All 123 in vitro growing MAP isolates from wild ruminants were of IS900 RFLP type B-C1. One mouflon infected with a MAP strain which did not grow on the tested media was after IS1311-PRA-PCR assessed as being infected with a "sheep" strain. The RFLP type of the MAP isolate from the wild boar was of the RFLP type A-C10. Although the detection of MAP in wildlife in the Czech Republic was not very high, their role as a potential risk factor for cattle should be considered.