Effects of housing conditions during the rearing and laying period on adrenal reactivity, immune response and heterophil to lymphocyte (H/L) ratios in laying hens

This study was conducted to evaluate the effect of early rearing conditions on physiological, haematological and immunological responses relevant to adaptation and long-term stress in white Leghorn hens with intact beaks housed in furnished cages (FC) or conventional cages (CC) during the laying period. Pullets were cage reared (CR) or litter floor reared (FR). From 16 to 76 weeks of age, hens were housed in FC (eight hens per cage) or in CC (three hens per cage). As measures of long-term stress at the end of the laying period, adrenal reactivity was quantified by assessing corticosterone responses to adrenocorticotropin challenge, and immune response was assessed by measuring antibody responses after immunization with sheep red blood cells (SRBC) and keyhole limpet haemocyanin (KLH). Heterophil to lymphocyte (H/L) ratio was employed as an indicator of stress. Rearing conditions significantly affected anti-SRBC titres (P < 0.0001) and tended to affect H/L ratios (P = 0.07), with the highest values found in FR hens. Layer housing affected H/L ratio (P < 0.01); the highest ratio was found in FR birds housed in FC during the laying period. This study shows that early rearing environment affects immunological indicators that are widely used to assess stress in laying hens. However, while results on H/L ratio indicated that FR birds experienced more stress particularly when they were housed in FC during the laying period, the immune responses to SRBC in FR hens was improved, indicating the opposite. This contradiction suggests that the effects on immune response may have been associated with pathogenic load due to environmental complexity in FR and FC hens rather than stress due to rearing system or housing system per se.     

Interactions of flavin containing monooxygenase 3 (FMO3) genotype and feeding of choline and rapeseed cake on the trimethylamine (TMA) content in egg yolks of laying hens

To evaluate the relationship between the FMO3 genotype and dietary trimethylamine (TMA) precursors on TMA-N content in eggs, laying hens were fed with choline (500 and 4000 mg/kg diet) and, in a later trial, with rapeseed cake (0, 100 and 300 g/kg diet). Hens were genotyped for non-synonymous A/T polymorphism at position nt1034 of the cDNA of the FMO3 gene, which is associated with elevated TMA-levels in egg yolks. Genotypes were equally distributed among the experimental diets. TMA was extracted from yolks and measured as TMA-N by a colorimetric method. As expected, hens of the TT-genotype had high amounts of TMA-N in egg yolks when fed either 4000 mg choline/kg diet or the rapeseed cake diet, while hens of the AA-genotype showed low levels of TMA-N. Heterozygous AT-hens had a slightly increased level of TMA-N when fed with 4000 mg choline/kg diet but not with the rapeseed cake feed. Rapeseed cake can be fed to AA and AT hens without leading to fishy tainted eggs.     

不同培养时间对鸡卵泡颗粒细胞孕酮、雌激素分泌水平及FSHR、LHR基因表达的影响

目的：研究培养不同时间鸡卵泡颗粒细胞孕酮和雌激素的分泌水平,促卵泡素受体（FSHR）和促黄体素受体（LHR）的基因表达水平,推断体外培养时间对颗粒细胞激素分泌及相关受体基因表达的影响。方法：通过细胞体外培养的方法,分别于0 h、24 h、48 h、72 h、96 h收集鸡卵泡颗粒细胞上清液,采用ELISA法测定细胞上清液内的孕酮及雌激素分泌水平,并采用荧光定量PCR技术检测颗粒细胞内FSHR和LHR基因表达情况。结果：在培养初期0 h~48 h孕酮和雌激素分泌量显著降低（P < 0.05）,随着培养时间增加到72 h两种激素的分泌量又开始增加,并达到培养初期水平,培养至96 h细胞内孕酮和雌激素分泌量再次降低;颗粒细胞FSHR和LHR mRNA的表达水平则随着培养时间的增加而降低（P < 0.05）。结论：体外培养的卵泡颗粒细胞内孕酮和雌激素的分泌量随体外培养时间的延长呈先降低后升高的趋势,可能与体外培养细胞的生长状态相关,从整体上看随着培养时间的延长,细胞内孕酮和雌激素的分泌量均降低,可能与两种促性腺激素受体FSHR和LHR基因表达量下降相关。     

Effects of an anti-androgen in the laying hen (Gallus domesticus)

The daily injection of the anti-androgen, cyproterone acetate, into regularly laying hens failed to prevent ovulation immediately. The delayed response suggested that testosterone is not part of the ovarian positive feedback stimulus resulting from the presence of an ovulable follicle and leading to ovulation. Ovarian changes in treated birds, and their unimpaired response to LH-RH, suggested that the drug might be acting by altering ovarian steroid metabolism.     

Assessment of the effect of housing on feather damage in laying hens using IR thermography

Plumage damage represents one of the animal-based measures of laying hens welfare. Damage occurs predominantly due to age, environment and damaging pecking. IR thermography, due to its non-invasiveness, objectivity and repeatability is a promising alternative to feather damage scoring systems such as the system included in the Welfare Quality^R assessment protocol for poultry. The aim of this study was to apply IR thermography for the assessment of feather damage in laying hens kept in two housing systems and to compare the results with feather scoring. At the start of the experiment, 16-week-old laying hens (n=30) were divided into two treatments such as deep litter pen and enriched cage. During 4 months, feather damage was assessed regularly in 2-week intervals. One more single assessment was done nine and a half months after the start of the experiment. The feather damage on four body regions was assessed by scoring and IR thermography: head and neck, back and rump, belly, and underneck and breast. Two variables obtained by IR thermography were used: the difference between the body surface temperature and ambient temperature (ΔT_B) and the proportion of featherless areas, which were defined as areas with a temperature >33.5°C. Data were analyzed using a GLM model. The effects of housing, time, region and their interactions on feather damage, measured by the feather scoring and by both IR thermography measures, were all significant (P<0.001). The ΔT_B in all assessed regions correlated positively with the feather score. Feather scoring revealed higher damage in enriched cages compared with deep litter pens starting from week 6 of the experiment on the belly and back and rump regions, whereas ΔT_B from week 6 in the belly and from week 8 on the back and rump region. The proportion of featherless areas in the belly region differed significantly between the housings from week 8 of the experiment and on the back and rump region from week 12. The IR thermography assessment of the feather damage revealed differences between hens kept in different housing systems in agreement with the feather scoring. In conclusion, it was demonstrated that the IR thermography is a useful tool for the assessment of poultry feather cover quality that is not biased by the subjective component and provides higher precision than feather damage scoring.     

Effects of a poly(ADP-ribose) polymerase inhibitor on mutation frequencies in dividing and quiescent C3H10T1/2 cells

The effect of 3-methoxybenzamide, an inhibitor of poly(ADP-ribose) polymerase, on N-methyl-N′-nitro-N-nitrosoguanidine-induced mutations has been examined in exponentially dividing cells where this inhibitor is a strong potentiator of cytotoxicity and in quiescent cells where the inhibitor has little or no effect on cell survival. The yield of mutants decreased in dividing cells by approximately 70% while mutation frequencies showed small but statistically significant increases in quiescent cells. These results suggest that apparent decreased mutation frequencies observed in the presence of ADP-ribosylation inhibitors are due to selective inhibition of expression of mutations in dividing cells caused by an irreversible G₂ cell cycle block.     

Effects of nanosized zinc oxide and γ-polyglutamic acid on eggshell quality and serum parameters of aged laying hens

In order to increase zinc (Zn) absorption and improve eggshell quality, diets for aged laying hens were supplemented with different Zn sources and the effects on egg production, eggshell quality and serum parameters were recorded. Seventy-five 64-week old brown layers were individually caged and randomly allotted to five treatment groups: an un-supplemented Control and four groups, where the following Zn sources were added to the diets, ZnO (group ZnO), Zn-methionine (group Zn-Met), nanosized ZnO (group nanoZnO) and γ-PGA-nano ZnO (group γ-PGA-nanoZnO). The Zn level was maintained at 80 mg/kg in the supplemented diet, while the Control group received Zn at 40 mg/kg diet. The results indicated that the average daily feed intake was highest in group nanoZnO (p < 0.05), whereas further performance parameters were not influenced by treatments. Eggshell thickness was increased in group γ-PGA-nanoZnO (p < 0.05). Zn content in eggshells and Zn concentration in serum were increased in groups Zn-Met, nanoZnO and γ-PGA-nanoZnO (p < 0.05). Serum ghrelin concentration was significantly elevated in all Zn-supplemented groups, but further increased in groups nanoZnO and γ-PGA-nanoZnO (p < 0.05). Carbonic anhydrase activity was highest in group γ-PGA-nanoZnO and lowest in group Zn-Met (p < 0.05). Compared to the Control and group ZnO, supplementation of γ-PGA-nanoZnO and nanoZnO increased serum IgG levels (p < 0.001). In conclusion, dietary supplementation of nanoZnO and γ-PGA-nanoZnO increased Zn content in eggshells, serum Zn concentration, ghrelin and IgG levels of aged layers when compared to regular ZnO. Compared to Zn-Met, the serum carbonic anhydrase activity and ghrelin levels were also increased. Thus, nanosized ZnO alone or mixed with γ-PGA has positive effects on the Zn status of aged layers.     

Effects of Enterococcus faecalis on egg production,egg quality and caecal microbiota of hens during the late laying period

This study was conducted to determine the effects of diet supplementation of laying hens with Enterococcus faecalis (EF) on egg production, egg quality and caecal microbiota. A total of 360 Hy-Line Brown laying hens (72 weeks old) were divided into three groups with four replicates of 30 birds each. The laying hens were fed with the basal diet (Control), the basal diet + 3.75 · 10⁸ cfu EF/kg (Group I) or the basal diet + 7.5 · 10⁸ cfu EF/kg (Group II). The experiment lasted for 45 d. Eggs and caecal samples were collected at the end of the experiment. Results showed that dietary supplementation with EF did not affect the average daily egg weight, cracked egg rate, mortality and egg quality. However, EF supplementation caused a significantly increased laying rate and decreased feed/egg ratio (p < 0.05). The differences in caecal microbiota between Group II and the Control were significant. The relative abundance of Verrucomicrobia and Cyanobacteria at the phylum level, Rikenellaceae, Christensenellaceae and Veillonellaceae at the family level, and the Faecalibacterium, Christensenellaceae R-7 group and Eubacterium coprostanoligenes group at the genus level changed significantly in Group II compared with the Control (p < 0.05). In conclusion, the tested dietary supplementations with EF improved product performance and affected the caecal microbial community structure of laying hens during the late laying period.     

The effect of replacing soya bean oil with glycerol in diets on performance,egg quality and egg fatty acid composition in laying hens

The objective of this experiment was to replace soya bean oil with glycerol in laying hen diets and assess the change’s effect on performance, parameters of egg quality and the egg fatty acid profile. A total of 60 44-week-old Hy-Line W36 laying hens were distributed according to a completely randomised experimental design into four treatments consisting of glycerol substitutions for soya bean oil dietary at varying inclusion levels (0%, 25%, 50% and 75%), with five replicates of three birds each. Dietary treatments had no significant effect on BW change, egg production, feed intake, feed conversion ratio, egg weight and egg mass of laying hens. The inclusion of glycerol in the diet of laying hens had no significant effect on egg specific gravity, eggshell breaking strength, eggshell weight, eggshell thickness, egg shape index, albumen index, yolk index, haugh unit, albumen pH, yolk pH and egg yolk colour values. The inclusion of glycerol in the diet of laying hens had no significant effect on palmitic, palmitoleic, stearic, oleic and linolenic acid contents of the egg yolk. The linoleic acid and polyunsaturated fatty acid contents of the egg yolk significantly decreased with the higher levels of dietary glycerol supplementation (P<0.05). The results of this study show that it is possible to replace 75% of soya bean oil (4.5% in diet) with glycerol.     

Indirect Genetic Effects for Survival in Domestic Chickens (Gallus gallus) Are Magnified in Crossbred Genotypes and Show a Parent-of-Origin Effect

Through social interactions, individuals can affect one another’s phenotype. The heritable effect of an individual on the phenotype of a conspecific is known as an indirect genetic effect (IGE). Although IGEs can have a substantial impact on heritable variation and response to selection, little is known about the genetic architecture of traits affected by IGEs. We studied IGEs for survival in domestic chickens (Gallus gallus), using data on two purebred lines and their reciprocal cross. Birds were kept in groups of four. Feather pecking and cannibalism caused mortality, as beaks were kept intact. Survival time was shorter in crossbreds than in purebreds, indicating outbreeding depression and the presence of nonadditive genetic effects. IGEs contributed the majority of heritable variation in crossbreds (87 and 72%) and around half of heritable variation in purebreds (65 and 44%). There was no evidence of dominance variance, neither direct nor indirect. Absence of dominance variance in combination with considerable outbreeding depression suggests that survival is affected by many loci. Direct–indirect genetic correlations were moderately to highly negative in crossbreds (−0.37 ± 0.17 and −0.83 ± 0.10), but low and not significantly different from zero in purebreds (0.20 ± 0.21 and −0.28 ± 0.18). Consequently, unlike purebreds, crossbreds would fail to respond positively to mass selection. The direct genetic correlation between both crosses was high (0.95 ± 0.23), whereas the indirect genetic correlation was moderate (0.41 ± 0.26). Thus, for IGEs, it mattered which parental line provided the sire and which provided the dam. This indirect parent-of-origin effect appeared to be paternally transmitted and is probably Z chromosome linked.     

Platinum determination in cis-dichlorodiammineplatinum(II)-DNA complexes by differential pulse polarography

A simple polarographic assay for platinum determination in cis-dichlorodiammineplatinum(II)-DNA complexes is described. The method makes it possible to determine the free (unbound) drug in the presence of DNA or platinum-DNA complex, i.e., without a separation of free drug and macromolecular components of the solution to be analyzed. This method is based on the polarographic activity of intact cis-dichlorodiammineplatinum(II) at ?1.5 V, which can be measured by differential pulse polarography even in the presence of DNA or platinum-DNA complex. The lower level of analytical utility of this method is ca. 1 × 10^?6m (195 ng of platinum/ml).     

Effects of early prenatal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on postnatal reproduction in the laying hen (Gallus gallus)

This study demonstrates the long-term effects of very early embryonic exposure to a single dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (0, 10 and 20 ng/egg), administered before the beginning of embryonic development, on growth and reproductive performance in laying hens. Hatchability and body weight gain from 11 weeks onwards were significantly depressed in 20 ng treated hens. All hens started laying egg at around the same age and the laying performance of TCDD-treated hens was normal. No disturbances in the age-related pattern and concentrations of oestradiol, LH or FSH in plasma could be found but mean progesterone concentrations were significantly lower in 20 ng treated hens. Moreover, follicular distribution was changed with less small white follicles and smaller yellow follicles, which probably resulted in the lower egg weight of the 20 ng treated hens. At 43 weeks of age, hens treated in ovo with TCDD showed a retained right oviduct, mostly filled with clear fluid. From these results, it seems that in ovo exposure to TCDD interferes in the right oviduct regression during embryonic development and induces some changes in follicular distribution but without impairment of reproductive performance in the adult laying hen.     

A note on fear reaction of three different genetic strains of laying hens to a simulated hawk attack in the hen run of a free-range system

Hens well adapted to free-range systems should react quickly to avoid an attack by a predator but should also be able to return to the hen run soon after to ensure good use of the outside area. To ascertain if some strains cope better with a frightening event the fear reaction of three different genetic strains to a simulated hawk attack in a free-range system was tested. Eight groups of 21 hens composed of the three different strains (LSL, ISA brown and ISA black), were exposed to a simulated hawk attack. Fear reaction and recovery times were video recorded and the use of the hen run was observed. Although the hens did react to the simulated hawk attack as expected by running back into or in direction to the poultry house, no significant strain differences were found either in the reaction or recovery time or in the course of the hen run used. Regarding fear reaction no strain was found to have better features for use as free-range laying hen regarding the behaviour after a frightening event.     

Effects of faba beans with different concentrations of vicine and convicine on egg production,egg quality and red blood cells in laying hens

The faba bean (Vicia faba L.) is a potential source of proteins for poultry, mainly for laying hens whose protein requirements are lower than those of other birds such as growing broilers and turkeys. However, this feedstuff contains anti-nutritional factors, that is, vicine (V) and convicine (C) that are already known to reduce laying hen performance. The aim of the experiment reported here was to evaluate the effects of a wide range of dietary V and C concentrations in laying hens. Two trials were performed with laying hens fed diets including 20% or 25% of faba bean genotypes highly contrasting in V+C content. In Trial 1, faba beans from two tannin-containing cultivars, but with high or low V+C content were dehulled in order to eliminate the tannin effect. In addition to the contrasting levels of V+C in the two cultivars, two intermediate levels of V+C were obtained by mixing the two cultivars (70/30 and 30/70). In Trial 2, two isogenic zero-tannin faba bean genotypes with high or low V+C content were used. In both trials, a classical corn–soybean diet was also offered to control hens. Each experimental diet was given to 48 laying hens for 140 (Trial 1) or 89 (Trial 2) days. Laying performance and egg quality were measured. The redox sensitivity of red blood cells (RBCs) was assessed by measuring hemolysis and reduced glutathione (GSH) concentration in these cells. Egg weight was significantly reduced by the diets containing the highest concentrations of V+C (P<0.0001) in Trial 1 and slightly reduced (P<0.10) in Trial 2, but only weak linear relationships between egg weight and dietary V+C concentration were established. No negative effect of V+C level was observed for egg quality parameters. In contrast, certain parameters (i.e. Haugh units, yolk color) were improved by feeding low V+C diets (P<0.05). Hemolysis of RBCs was higher in hens fed high V+C diets. A decrease in GSH concentration in RBCs of hens fed the highest levels of V+C was observed. Faba bean genotypes with low concentrations of V+C can therefore be used in laying hen diets up to 25% without any detrimental effects on performance levels or egg characteristics, without any risk of hemolysis of RBCs.     

Effects of probiotic supplementation on performance traits,bone mineralization,cecal microbial composition,cytokines and corticosterone in laying hens

Recent researches have showed that probiotics promote bone health in humans and rodents. The objective of this study was to determine if probiotics have the similar effects in laying hens. Ninety-six 60-week-old White Leghorn hens were assigned to four-hen cages based on their BW. The cages were randomly assigned to 1 of 4 treatments: a layer diet mixed with a commercial probiotic product (containing Enterococcus faecium, Pediococcus acidilactici, Bifidobacterium animalis and Lactobacillus reuteri) at 0, 0.5, 1.0 or 2.0 g/kg feed (Control, 0.5×, 1.0× and 2.0×) for 7 weeks. Cecal Bifidobacterium spp. counts were higher in all probiotic groups (P<0.001) compared with the control group. The percentage of unmarketable eggs (cracked and shell-less eggs) was decreased in both 0.5× and 2.0× groups compared with the control group (P=0.02), mainly due to the reduction of shell-less eggs (P=0.05). The increases in tibial and femoral mineral density and femoral mineral content (P=0.04, 0.03 and 0.02, respectively), with a concomitant trend of increases in humerus mineral density and tibial mineral content (P=0.07 and 0.08, respectively), occurred in the 2.0× group. However, the bone remodeling indicators of circulating osteocalcin and c-terminal telopeptide of type I collagen were similar among all groups (P>0.05). In addition, the plasma concentrations of cytokines (interleukin-1β, interleukin-6, interleukin-10, interferon-γ and tumor necrosis factor-α) and corticosterone as well as the levels of heterophil to lymphocyte ratio were similar between the 2.0× group and the control group (P>0.05). In line with these findings, no differences of cecal tonsil mRNA expressions of interleukin-1β, interleukin-6 and lipopolysaccharide-induced tumor necrosis factor-α factor were detected between these two groups (P>0.05). These results suggest that immune cytokines and corticosterone may not involve in the probiotic-induced improvement of eggshell quality and bone mineralization in laying hens. In conclusion, the dietary probiotic supplementation altered cecal microbiota composition, resulting in reduced shell-less egg production and improved bone mineralization in laying hens; and the dietary dose of the probiotic up to 2.0× did not cause negative stress reactions in laying hens.     

Temporal variation of allele frequencies in populations of Akodon dolores (Rodentia,Cricetidae)

Summary Six population samples of the South American cricetid rodent Akodon dolores were collected at the same site at six-month intervals over a three year period. Changes in density were detected. Seven out of 18 loci analyzed by means of starch gel electrophoresis were polymorphic. Only two of these loci (Est-4 and G6pdh) showed statistically significant variation in allele frequencies following a seasonal pattern. There was no correlation between allele frequencies and population density. When animals were grouped into two classes according to body weight, a clear difference in allele distribution at the Est-4 and G6pdh loci was observed between individuals 39 g or less and those heavier than 39 g. As the first group comprises predominantly younger animals, the data indicate that changes in the age-structure of population, rather than density variations, are responsible for the cyclic pattern of allele frequencies fluctuations.     

Effects of differentiation of embryonal carcinoma cells (P19) on mitochondrial DNA content in vitro

Summary The embryonal carcinoma cell line P19 is derived from mouse teratocarcinomas. These pluripotent cells can be induced to differentiate into a variety of cell types by exposure to various drugs. We used retinoic acid to induce embryonal carcinoma cells to differentiate into neuronlike cells. In this study, we show that changes occur in mitochondria during differentiation of embryonal carcinoma cells to neuronlike cells. We found that various morphologic parameters such as mitochondrial fractional area and mitochondrial size decrease as embryonal carcinoma cells differentiate into neuronlike cells. Similar changes were also observed in mitochondrial DNA content. Stereologic analysis of cell preparations provided a measure of mitochondrial fractional area per cell and mtDNA content was assessed by radiolabeled mtDNA probe. This study establishes that mitochondria are regulated as cells differentiate. This study was financially supported by the Medical Research Council of Canada.     

Spatial patterns of egg laying and multiple parasitism in a brood parasite: a non-territorial system in the great spotted cuckoo (Clamator glandarius)

We analysed the spatial and temporal pattern of egg laying in great spotted cuckoo females using microsatellite typing to determine parentage of the eggs and nestlings found in host (magpie) nests. The results showed that there were no exclusive laying territories in the study area. Cases of multiparasitism could be due to single females laying two or more eggs in a nest, or to several females using the same nest. In the latter case multiparasitism was due to a shortage of available host nests. We argue that the need for very large laying areas and the likely small cost of sharing parental care for chicks make the costs of defending territories higher than the benefits, which has constrained the evolution of territoriality in this species. Received: 16 March 1998 / Accepted: 15 June 1998