Feather pecking (FP) in laying hens remains an important economic and welfare issue. This paper reviews the literature on causes of FP hens. With ban conventional cages EU from 2012 expected future beak trimming many European countries, addressing this issue has become more pressing than ever. The aim review is to provide a detailed overview underlying principles FP. affected by different factors any approach prevent or reduce commercial flocks should acknowledge that fact use multifactorial...

Birds rearing experimentally enlarged broods have lower antibody responses to a novel antigen, and we tested three hypotheses that could explain this result. We used zebra finches Taeniopygia guttata inoculated with sheep red blood cells (SRBC) as study system, for which trade‐off was previously demonstrated. 1. Compensatory cellular immunity: The humoral immune response is slow, removal of SRBC through up‐regulated immunity pre‐empt an response. However, PHA decreased increasing brood size,...

We used the doubly labeled water (DLW) method to measure daily energy expenditure (DEE) in eight brother-sister pairs of free-living Marsh Harrier (Circus aeruginosus) nestlings. calculated metabolizable intake (ME) from DEE and body-mass change. In each pair, males had lower body mass, DEE, ME than their female siblings. On average, male mass was 20%, 19%, 20% that Thus, turnover proportional mass. Because average sex ratio at fledging Harriers is 55% male, requirement sons 45% son-daughter...

Individual differences in laterality and personality are expected to covary, as emotions processed differently by the two hemispheres, involves emotional behavior. Fish species often used investigate this topic due large variability patterns. While some show a positive relationship between lateralization strength boldness, others negative relationship, no relationship. A new way assess robustness of such is manipulate both examine how affects their To end, we conducted fully factorial design...

Abstract Cognitive bias is defined as the influence of emotions on cognitive processes. The concept judgement has its origins in human psychology but been applied to animals over past 2 decades. In this study we were interested determining if laterality and personality traits, which are known learning style, might also be correlated with a three-spined sticklebacks ( Gasterosteus aculeatus ). We used test go/no-go procedure where fish first trained discriminate between black white card and,...

When the reproductive value of male and female offspring varies differentially, parents are predicted to adjust sex ratio their maximize fitness (Trivers Willard, Science 179:90-92, 1973). Two factors have been repeatedly linked skews in avian ratio. First, laying date can affect when sexes differ age first reproduction, such that more slowly maturing is overproduced early season. Second, position egg sequence a clutch may bias since manipulating eggs be least costly mother. We studied both...

Maternal androgen exposure can have crucial effects on offspring development. Bird eggs are frequently used for studying these and virtually all research in this field has focused post-hatching traits. Yet, much of the yolk, which maternal hormones deposited, is consumed during embryonic phase. Here, we studied yolk androgens prenatal period. As there evidence that stimulate traits such as increased growth, measured heart rate throughout incubation a proxy metabolism. Rock pigeons (Columba...

Abstract Substantial concentrations of testosterone are not only present in a male’s circulation, but also its ejaculate. Surprisingly, the regulation ejaculate T and effects on females their offspring, potentially cryptic paternal trait, known. We found lower circulating higher subordinate red junglefowl ( Gallus gallus ) males compared to dominant males, suggestive an adaptive trade-off allocation circulation Subsequently, we artificially inseminated with either enriched (TE) or control...

Maternal androgen exposure has potent effects on offspring development. As substantial levels of maternal androgens are deposited in avian egg yolks, eggs frequently used to study effects, with a strong focus post-natal However, the underlying pathways largely unknown. Since hormones taken up during embryonic phase, and these rapidly metabolized by embryos into metabolites such as etiocholanolone, we studied yolk (testosterone androstenedione) their metabolite etiocholanolone first few days...

Offspring phenotypes can be affected by maternal testosterone (T) and androstenedione (A4), which are considered a tool of mothers to adjust offspring in fluctuating environment. Yet T A4 found very rapidly metabolized developing avian embryos, suggesting that either the have potent organizational effects on embryos extremely early before being or it's metabolites evoke phenotypic variation offspring. One metabolites, etiocholanolone, increases substantially during embryonic development is...

Understanding equestrians' noseband tightening practices and intentions is necessary to target welfare improvement strategies. Firstly, we measured tightness in dressage show jumping horses The Netherlands, shortly after implementation of the two-finger rule by Royal Dutch Equestrian Federation. Noseband decreased with age, was less tight than jumpers, dependent on interaction between competition level discipline. Fifty-nine percent riders tightened nosebands such an extent that they adhered...

In birds, exposure to maternal (yolk) testosterone affects a diversity of offspring post-hatching traits, which eventually affect competitiveness. However, is heavily metabolized at very early embryonic developmental stages hydrophilic metabolites that are often assumed be much less biologically potent. Either the rapid metabolism could either keep from reaching embryos, opening possibility for mother–offspring conflict or may facilitate uptake lipophilic yolk into circulation after they...

We investigated the trade-off between sleep need and alertness, by challenging chickens to modify their monocular sleep. deprived domestic (Gallus domesticus) increase need. found that in response deprivation fraction of within decreased favour binocular These data suggest with a high choose perform more sleep, possibly at cost reduced alertness.

Abstract Many mammalian species use photoperiod as a predictive cue to time seasonal reproduction. In addition, metabolic effects on the reproductive axis may also influence timing, especially in female small, short‐lived mammals. To get better understanding of how annual cycling environmental cues impact function and plasticity herbivores with different geographic origins, we investigated mechanisms underlying integration temperature photoperiodic‐axis regulating reproduction Northern vole...

Summary Early exposure to steroid hormones, as in the case of an avian embryo exposed yolk testosterone, can impact biology individual different ways over course its life. While many early‐life effects testosterone have been documented, later‐life remain poorly studied. We followed a cohort twenty captive pigeons hatched 2005. Half these birds came from eggs with experimentally increased concentrations testosterone; half control eggs. Preliminary results suggest non‐random mortality during...

Several factors affect the development of lateralization such as hormones and light exposure during early development. Laterality also often correlates with other behavioral traits. To examine whether there is a common mechanism underlying laterality behaviors, we manipulated by exposing embryos Western rainbowfish (Melatotaenia australis) to or continuous darkness determined shift in was associated change behavior novel environment test at two different ages. We found that eggs led...