20 resultados para The Nest

em BORIS: Bern Open Repository and Information System - Berna - Suiça


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Low rates of nest acceptance by laying hens are a major problem in commercial poultry farming operations with aviary systems, leading to costly manual collection and cleaning of mislaid eggs. To gain knowledge about factors affecting nest use, laying hens' preferences for different nest locations were tested. Nests are normally installed at one of two sites: against a wall of the hen house or integrated into one tier of the aviary rack The preferences of laying hens for different nest sites have never been examined under commercial conditions. The aim of this study is to investigate whether behavioural differences can be detected between the different nest sites. The study consists of two consecutive trials involving 5027 Lohmann Selected Leghorn hens (LSL) and 601 layer hybrids selected for extensive housing conditions (EXT). The hens were randomly assigned to eight compartments per trial in groups of 355-360 LSL or 300 EXT in a laying hen house. Four compartments were equipped with a Volito Voletage (R) aviary system (VV), and four were equipped with a Rihs Bolegell (R) aviary system (RB), both of which contained either integrated or wall-placed nests when the experiments started. A strongly balanced crossover design with four periods was used. At 36, 44 and 52 weeks of age, the nest site in four out of the eight compartments was switched. Before each change, the fronts of half of the nests were videotaped during the light period, and the behaviour throughout the main laying period was analysed. Furthermore, the numbers of nest eggs and mislaid eggs in each compartment were recorded every day. No differences in the number of mislaid eggs between the two nest sites could be detected, except at the age of 20/21 weeks when hens in VV aviaries mislaid more eggs when nests were integrated (P = 0.0012). More hens stood simultaneously in front of the integrated nests than in front of wall-placed nests (P = 0.015). Activity of the laying hens increased (P = 0.0073), and stationary behavioural patterns declined (P = 0.0093), when the nests were placed by the wall. Hens inspected integrated nests for a longer duration than wall-placed nests, but wall-placed nests were visited more frequently. In addition to the nest site, the width of the platform in front of the nest influenced laying hen behaviour. Compared with narrower platforms, balance movements decreased on wider ones. Additionally, the platform design had to be taken into account as well, given that hens could not stand or walk as securely on wooden slats as on a grid floor. (C) 2011 Elsevier B.V. All rights reserved.

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The influence of the nest location and the placement of nipple drinkers on nest use by laying hens in a commercial aviary was assessed. Twenty pens in a laying hen house were equipped with the same commercial aviary system, but the pens differed in the nest location and the placement of nipple drinkers. Nests were placed along the walls in 10 pens, and nipple drinkers were installed in front of the nests in 5 of these pens. The other 10 pens were equipped with nests placed on a tier within the aviary (integrated nests). Nipple drinkers were installed in front of the nests in 5 of these pens. A total of 225 Lohmann Selected Leghorns were housed per pen. The hens were offered 4 nests per pen: 2 facing the service corridor of the laying hen house and 2 facing the outdoor area. The numbers of nest eggs and mislaid eggs were counted daily per pen. At 25, 36, and 43 wk of age, the nest platforms were videotaped and the behavior of laying hens in front of the nests was analyzed. The nest location affected the stationary and locomotive behaviors in front of the nests. Hens in front of the integrated nests and the nests with drinkers displayed more stationary behaviors than hens in front of wall-placed nests or nests without drinkers. No difference in the number of nest eggs could be detected, but the integration of the nests inside the aviary led to a more even distribution of hens while nest searching. In the pens with wall-placed nests, significantly more hens laid eggs in the nests at the wall near the service corridor than at the wall near the outdoor area. Due to this imbalance, crowding in front of the preferred nests occurred and pushing and agonistic interactions on the nest platforms were significantly more frequent. Placement of nipple drinkers in front of nests had no effect on the number of eggs laid in those nests.

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In aviary systems for laying hens, it is important to provide suitable nest access platforms in front of the nests, allowing hens to reach and explore each of the nests easily. This access platform is needed to achieve good nest acceptance by the hens and thereby prevent mislaid eggs. In the present experiment, the behavior of hens using 2 different nest access platforms, a plastic grid and 2 wooden perches, was examined. Furthermore, the nests were placed on both sides of the aviary rack (corridor side and outdoor side), either integrated into the aviary rack itself (integrated nest; IN) or placed on the walls of the pens (wall nest; WN), resulting in a 2 × 2 factorial design Four thousand five hundred white laying hens were housed in 20 test pens. The eggs in the nests and mislaid eggs were collected daily, and the behavior of hens on the nest accesses was filmed during wk 25 and 26, using focal observation and scan sampling methods. More balancing, body contact, and agonistic interactions were expected for nests with perches, whereas more walking and nest inspections were expected for nests with grids. There were more mislaid eggs and balancing found in pens equipped with nests with wooden perches. More agonistic interactions and balancing, less standing, and a longer duration of nest inspection were found with the WN compared with the IN. Interactions between platform design and position of the nests were found for duration of nest visits, body contact, and walking, with the highest amount for WN equipped with plastic grids. Nests on the corridor side were favored by the hens. Nest-related behaviors, such as nest inspection, standing, and walking, decreased over time as did the number of hens on the nest accesses, whereas sitting increased. These results indicate that the hens had more difficulties in gripping the perches as designed. The lower number of hens on the nest access platforms in front of IN may be due to a better distribution around nests and tier changes within the aviary rack. Based on these results, grids rather than perches provide for improved nesting behavior.

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Laying hens in loose housing systems have access to group-nests which provide space for several hens at a time to lay their eggs. They are thus rather large and the trend in the industry is to further increase the size of these nests. Though practicality is important for the producer, group-nests should also cater to the egg-laying behaviour of hens to promote good welfare. One of the factors playing a role in the attractiveness of a nest is the amount of enclosure: hens prefer more enclosure when having a choice between different nest types. The aim of this study was to investigate if hens prefer smaller group-nests to lay their eggs given that they may seem more enclosed than larger nests. The relative preference of groups of laying hens for two nest sizes – 0.43m2 vs. 0.86m2 – was tested in a free-access choice test. The experiment was conducted in two consecutive trials with 100 hens each. They were housed from 18 to 36 weeks of age in five groups of 20 animals and had access to two commercial group-nests differing in internal size only. We counted eggs daily as a measure of nest preference. At 28 and 36 weeks of age, videos were taken of the pens and inside the nests on one day during the first 5h of lights-on. The nest videos were used to record the number of hens per nest and their behaviour with a 10min scan sampling interval. The pen videos were observed continuously to count the total number of nest visits per nest and to calculate the duration of nest visits of five focal hens per pen. We found a relative preference for the small nest as more eggs, fewer nest visits per egg and longer nest visit durations were recorded for that nest. In addition, more hens – including more sitting hens – were in the small nests during the main egg-laying period, while the number of standing hens did not differ. These observations indicate that even though both nests may have been explored to a similar extent, the hens preferred the small nest for egg-laying.

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Laying hens in loose-housing systems select a nest daily in which to lay their eggs among many identical looking nests, they often prefer corner nests. We investigated whether heterogeneity in nest curtain appearance – via colours and symbols – would influence nest selection and result in an even distribution of eggs among nests. We studied pre-laying behaviour in groups of 30 LSL hens across two consecutive trials with eight groups per trial. Half of the groups had access to six identical rollaway group-nests, while the others had access to six nests of the same type differing in outer appearance. Three colours (red, green, yellow) and three black symbols (cross, circle, rectangle) were used to create three different nest curtain designs per pen. Nest position and the side of entrance to the pens were changed at 28 and 30 weeks of age, respectively, whereby the order of changes was counterbalanced across trials. Nest positions were numbered 1–6, with nest position 1 representing the nest closest to the pen entrance. Eggs were counted per nest daily from week of age 18 to 33. Nest visits were recorded individually with an RFID system for the first 5 h of light throughout weeks 24–33. Hens with access to nests differing in curtain appearance entered fewer nests daily than hens with identical nests throughout the study but both groups entered more nests with increasing age. We found no other evidence that curtain appearance affected nest choice and hens were inconsistent in their daily nest selection. A high proportion of eggs were laid in corner nests especially during the first three weeks of lay. The number of visits per egg depended upon nest position and age: it increased with age and was higher after the nest position change than before in nest position 1, whereas it stayed stable over time in nest position 6. At 24 weeks of age, gregarious nest visits (hens visiting an occupied nest when there was at least one unoccupied nest) and solitary nest visits (hens visiting an unoccupied nest when there was at least one occupied nest) accounted for a similar amount of nest visits, however, after the door switch, gregarious nest visits made up more than half of all nest visits, while the number of solitary nest visits had decreased. The visual cues were too subtle or inadequate for hens to develop individual preferences while nest position, entrance side, age and nest occupancy affected the quantity and type of nest visits.

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Nest choice in loose-housed laying hens is influenced by nest characteristics, position and social factors. We examined the relative preference of laying hens for two group-nests differing in the presence or absence of a partition in the middle of the nest and whether this was influenced by social status. We hypothesized that hens would prefer the partitioned nest as it provides more enclosure, and that social status would affect nest choice. Relative preference for the nests was assessed in a free choice preference test conducted in two consecutive trials each with eight groups of 20 hens from 18 to 31 weeks of age. The hens were individually marked and had access to two commercial group-nests (49 × 114 cm), one of which contained an internal wooden partition (30 × 10 cm) which divided the nest in two halves. At 28 weeks of age, the position of the nests was switched. The number of eggs laid was recorded daily. On one day each at 24 and 28 weeks of age (after the nest switch) video recordings were made of the first 5 h of daylight. From these videos we recorded the number of nest visits per egg per nest and the number of nest visits for individual hens. On one day each at 24 and 27 weeks of age we also recorded videos from within the nests to assess individual nest choice for egg-laying. In addition, we recorded aggressive interactions between individual hens during the first hour of light on one day each at 18, 24 and 27 weeks of age to establish social status. We found a relative preference for the partition nest with a greater proportion of eggs laid in these nests as well as fewer nest visits per egg. The hens were also consistent in their egg-laying location over the two days of observation. After the nest switch, however, the hens did not switch egg laying location and the number of visits per egg no longer differed between nests suggesting that the preference for the partitioned nest was only important at the beginning of lay. In addition, although social rank had no impact on preference of nest type, lower ranking hens performed more nest visits and laid their eggs slightly later on the second observation day (week 27 of age) compared with higher ranking hens. Therefore, the use of partitions could improve the attractiveness of group-nests.

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Current theory proposes that nestlings beg to signal hunger level to parents honestly, or that siblings compete by escalating begging to attract the attention of parents. Although begging is assumed to be directed at parents, barn owl (Tyto alba) nestlings vocalize in the presence but also in the absence of the parents. Applying the theory of asymmetrical contests we experimentally tested three predictions of the novel hypothesis that in the absence of the parents siblings vocally settle contests over prey items to be delivered next by a parent. This 'sibling negotiation hypothesis' proposes that offspring use each others begging vocalization as a source of information about their relative willingness to contest the next prey item delivered. In line with the hypothesis we found that (i) a nestling barn owl refrains from vocalization when a rival is more hungry, but (ii) escalates once the rival has been fed by a parent, and (iii) nestlings refrain from and escalate vocalization in experimentally enlarged and reduced broods, respectively. Thus, when parents are not at the nest a nestling vocally refrains when the value of the next delivered prey item will be higher for its nest-mates. These findings are the exact opposite of what current models predict for begging calls produced in the presence of the parents. [References: 20]

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Sibling and parente-offspring conflicts arise mainly over the amount and distribution of parental care, especially food. In altricial bird species where the young depend on parents for obtaining food, parents may control sibling competition by the choice of their respective provisioning locations. In great tits, the parents use fixed provisioning positions on the nest rim that are determined early in the breeding cycle and maintained until. edging. The two parents may choose positions that are close to each other, or far apart, and thereby increase or relax the pressure for optimal feeding positioning among nestlings. As an inspiration to this study we previously found that the two parents provide food from closer positions if the nest is infested by ectoparasites. Here, we tested the hypothesis that the parental choice of relative provisioning locations could be strategically used to control nestling competition. We forced parents to feed from either one or two provisioning locations and assessed the induced change in nestling movement, weight gain, and food distribution among siblings. We show that the angular distance between male and female locations influences the level of behavioural competition and affects nestling weight gain and food distribution. It is the first evidence for hole-nesting birds, where it was assumed that the nestling closest to the entrance hole was fed first, that the apparent choice of feeding positions by parents could be a way of controlling sibling competition and thereby also taking partial control over the outcome of parente-offspring conflict. (c) 2007 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

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1.In species with plastic expression of alternative reproductive tactics (ARTs), individuals of the same sex, usually males, can adopt different reproductive tactics depending on factors such as body size. 2.The ‘birth date hypothesis’ proposes that condition-dependent expression of ARTs may ultimately depend on birth date, because individuals born at different times of the year may achieve different sizes and express different reproductive tactics accordingly. However, this has rarely been tested. 3.Here, we tested this hypothesis in a fish with ARTs, the peacock blenny (Salaria pavo). A long-term (6 years) mark–recapture study demonstrated that ARTs in the peacock blenny were sequential and that males may follow at least two alternative life-history pathways: a nest-holder pathway, in which males express the nest-holder tactic from their first breeding season onwards, and a parasitic pathway, where males reproduce on their first breeding season as sneaker males and subsequently as nest-holders. 4.We have found evidence of a birth date effect on the expression of ARTs in the peacock blenny. Males following the nest-holder pathway are born earlier and are larger at the first breeding season than males following the parasitic pathway, but they have similar growth curves. 5.The mechanisms underlying a birth date effect are far from clear and might be diverse. We have not found support for a mechanism of body size threshold triggering sexual maturation and subsequent ARTs. A mechanism of tactic determination that is strictly based on timing of first maturation is also unlikely. 6.A proxy of lifetime reproductive success shows crossing (body size associated) fitness curves for the two main life-history pathways.

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Measuring the ratio of heterophils and lymphocytes (H/L) in response to different stressors is a standard tool for assessing long-term stress in laying hens but detailed information on the reliability of measurements, measurement techniques and methods, and absolute cell counts is often lacking. Laying hens offered different sites of the nest boxes at different ages were compared in a two-treatment crossover experiment to provide detailed information on the procedure for measuring and the difficulties in the interpretation of H/L ratios in commercial conditions. H/L ratios were pen-specific and depended on the age and aviary system. There was no effect for the position of the nest. Heterophiles and lymphocytes were not correlated within individuals. Absolute cell counts differed in the number of heterophiles and lymphocytes and H/L ratios, whereas absolute leucocyte counts between individuals were similar. The reliability of the method using relative cell counts was good, yielding a correlation coefficient between double counts of r > 0.9. It was concluded that population-based reference values may not be sensitive enough to detect individual stress reactions and that the H/L ratio as an indicator of stress under commercial conditions may not be useful because of confounding factors and that other, non-invasive, measurements should be adopted.

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Workers from social insect colonies use different defence strategies to combat invaders. Nevertheless, some parasitic species are able to bypass colony defences. In particular, some beetle nest invaders cannot be killed or removed by workers of social bees, thus creating the need for alternative social defence strategies to ensure colony survival. Here we show, using diagnostic radioentomology, that stingless bee workers (Trigona carbonaria) immediately mummify invading adult small hive beetles (Aethina tumida) alive by coating them with a mixture of resin, wax and mud, thereby preventing severe damage to the colony. In sharp contrast to the responses of honeybee and bumblebee colonies, the rapid live mummification strategy of T. carbonaria effectively prevents beetle advancements and removes their ability to reproduce. The convergent evolution of mummification in stingless bees and encapsulation in honeybees is another striking example of co-evolution between insect societies and their parasites.

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Native to sub-Saharan Africa, Aethina tumida Murray (Coleoptera: Nitidulidae) is now an invasive pest of honey bee, Apis mellifera L., colonies in Australia and North America. Knowledge about the introduction (s) of this beetle from Africa into and among the current ranges will elucidate pest populations and invasion pathways and contribute to knowledge of how a parasite expands in new populations. We examined genetic variation in adult beetle samples from the United States, Australia, Canada, and Africa by sequencing a 912-base pair region of the mitochondrial DNA cytochrome c oxidase subunit I gene and screening 10 informative microsatellite loci. One Canadian introduction of small hive beetles can be traced to Australia, whereas the second introduction seems to have come from the United States. Beetles now resident in Australia were of a different African origin than were beetles in North America. North American beetles did not show covariance between two mitochondrial haplotypes and their microsatellite frequencies, suggesting that these beetles have a shared source despite having initial genetic structure within their introduced range. Excellent dispersal of beetles, aided in some cases by migratory beekeeping and the bee trade, seems to lead to panmixis in the introduced populations as well as in Africa.

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Numerous bacterial pathogens subvert cellular functions of eukaryotic host cells by the injection of effector proteins via dedicated secretion systems. The type IV secretion system (T4SS) effector protein BepA from Bartonella henselae is composed of an N-terminal Fic domain and a C-terminal Bartonella intracellular delivery domain, the latter being responsible for T4SS-mediated translocation into host cells. A proteolysis resistant fragment (residues 10-302) that includes the Fic domain shows autoadenylylation activity and adenylyl transfer onto Hela cell extract proteins as demonstrated by autoradiography on incubation with α-[(32)P]-ATP. Its crystal structure, determined to 2.9-Å resolution by the SeMet-SAD method, exhibits the canonical Fic fold including the HPFxxGNGRxxR signature motif with several elaborations in loop regions and an additional β-rich domain at the C-terminus. On crystal soaking with ATP/Mg(2+), additional electron density indicated the presence of a PP(i) /Mg(2+) moiety, the side product of the adenylylation reaction, in the anion binding nest of the signature motif. On the basis of this information and that of the recent structure of IbpA(Fic2) in complex with the eukaryotic target protein Cdc42, we present a detailed model for the ternary complex of Fic with the two substrates, ATP/Mg(2+) and target tyrosine. The model is consistent with an in-line nucleophilic attack of the deprotonated side-chain hydroxyl group onto the α-phosphorus of the nucleotide to accomplish AMP transfer. Furthermore, a general, sequence-independent mechanism of target positioning through antiparallel β-strand interactions between enzyme and target is suggested.