White Leghorn Hens Research Articles

Intestinal inflammation induced by dextran sodium sulphate causes liver inflammation and lipid metabolism disfunction in laying hens

Gut inflammation caused by various factors including microbial infection leads to disorder of absorption of dietary nutrients and decrease in egg production in laying hens. We hypothesized that intestinal inflammation may affect egg production in laying hens through its impact on liver function. Dextran sodium sulphate (DSS) is known to induce intestinal inflammation in mammals, but whether it also induces inflammation in laying hens is not known. The goal of this study was to assess whether oral administration of DSS is a useful model of intestinal inflammation in laying hens and to characterize the effects of intestinal inflammation on egg production using this model. White Leghorn hens (350-day old) were administrated with or without 0.9 g of DSS/kg BW in drinking water for 5 D (n = 8, each). All laid eggs were collected, and their whole and eggshell weights were recorded. Blood was collected every day and used for biochemical analysis. Liver and intestinal tissues (duodenum, jejunum, ileum, cecum, cecal-tonsil, and colon) were collected 1 D after the final treatment. These tissue samples were used for histological analysis and PCR analysis. Oral administration of DSS in laying hens caused 1) histological disintegration of the cecal mucosal epithelium and increased monocyte/macrophage infiltration and IL-1β, IL-6, CXCLi2, IL-10, and TGFβ-4 gene expression; 2) decreased egg production; 3) increased leukocyte infiltration and IL-1β, CXCLi2, and IL-10 expression in association with a high frequency of lipopolysaccharide-positive cells in the liver; and 4) decreased expression of genes related to lipid synthesis, lipoprotein uptake, and yolk precursor production. These results suggested that oral administration of DSS is a useful method for inducing intestinal inflammation in laying hens, and intestinal inflammation may reduce egg production by disrupting egg yolk precursor production in association with liver inflammation.

Choline supplementation alters egg production performance and hepatic oxidative status of laying hens fed high-docosahexaenoic acid microalgae

The purpose of the current study was to investigate the effect of choline as a means of increasing docosahexaenoic acid (22:6 n-3, DHA) deposition in egg yolks of hens fed a high-DHA microalgae product. Fifty-six, 26-wk-old, White Leghorn hens were kept in individual cages and randomly allocated to 1 of 4 dietary treatments, each with 7 replicate groups of 2 hens (n = 7 per treatment). The experimental diets were corn and soybean meal based, with 0% microalgae (control), 1% microalgae and no additional choline chloride (Alg), and Alg plus choline chloride at 0.1% (Ch0.1) and 0.2% (Ch0.2). The feeding trial lasted 16 wk. The data were fit as a general linear mixed model to generate least square means in response to diet. Variables measured multiple times during the study were fit as repeated measures. Using orthogonal contrasts, Alg was compared to control, and Ch0.1 and Ch0.2 were compared separately to Alg. Ch0.1 increased hen day egg production (P < 0.05) and Haugh unit (P < 0.05), and reduced feed conversion ratio (P < 0.05) compared to Alg, but Ch0.2 did not. Alg increased egg DHA (P < 0.001), phosphatidylethanolamine (P < 0.05), and phosphatidylcholine (P < 0.001) compared to control, but Ch0.1 or Ch0.2 had no effect compared to Alg (P > 0.05). In the liver, Alg increased lipid peroxidation products compared to control (P < 0.01), and Ch0.1 reduced them compared to Alg (P < 0.01). Both Ch0.1 and Ch0.2 increased hepatic concentrations of γ- (P < 0.05; P < 0.001) and α-tocopherol (P < 0.01; P < 0.001), and Ch0.1 increased γ-tocopherol concentration in eggs compared to Alg (P < 0.05). The results from the current study suggest that supplemental choline chloride in hen diets containing microalgae can improve production performance and egg quality, and protect the liver from oxidative stress.

Maternally-Derived Antibodies Protect against Challenge with Highly Pathogenic Avian Influenza Virus of the H7N3 Subtype.

Vaccination of hens against influenza leads to the transfer of protective maternally-derived antibodies (MDA) to hatchlings. However, little is known about the transfer of H7N3 vaccine-induced MDA. Here, we evaluated transfer, duration, and protective effect of MDA in chickens against H7N3 HPAIV. To generate chickens with MDA (MDA (+)), 15-week-old White Leghorn hens were vaccinated and boosted twice with an inactivated H7N3 low pathogenic avian influenza virus vaccine, adjuvanted with Montanide ISA 71 VG. One week after the final boost, eggs were hatched. Eggs from non-vaccinated hens were hatched for chickens without MDA (MDA (−)). Both MDA (+) and MDA (−) hatchlings were monitored weekly for antibody levels. Anti-HA MDA were detected by hemagglutination inhibition assay mostly until day 7 post-hatch. However, anti-nucleoprotein MDA were still detected three weeks post-hatch. Three weeks post-hatch, chickens were challenged with 106 EID50/bird of Mexican-origin H7N3 HPAIV. Interestingly, while 0% of the MDA (−) chickens survived the challenge, 95% of the MDA (+) chickens survived. Furthermore, virus shedding was significantly reduced by day 5 post-challenge in the MDA (+) group. In conclusion, MDA confers partial protection against mortality upon challenge with H7N3 HPAIV, as far as three weeks post-hatch, even in the absence of detectable anti-HA antibodies, and reduce virus shedding after challenge.

Characterization and production of IgY antibodies anti-Photobacterium damselae subsp. piscicida: Therapeutic and prophylactic use in Rachycentron canadum

Pseudotuberculosis is caused by Photobacterium damselae subsp. piscicida (Phdp), an important pathogen in marine fish culture. In this study, Phdp isolated from a Rachycentron canadum farm was used to produce anti-Photobacterium damselae IgY and its protective effect were evaluated in R. canadum challenged with the homologous strain. The IgY was obtained from egg yolks of White Leghorn hens using polyethylene glycol precipitation method. Anti-Phdp IgY showed strongly specific reaction against Phdp proteins. Finally, it was performed the antibody efficacy in vivo to determinate their prophylactic and therapeutic effects during sepsis in R. canadum. For this, fish received anti-Phdp IgY 48 h and 15 days before the challenged with the homologous bacteria of Phdp. In these groups, it was observed less liver and kidney lesions comparing to control group, which was also correlated to the biochemical profile. In this study, it was also developed an immunohistochemistry test that presented highly specificity and affinity to Phdp that could be used as screening method for the diagnosis and analysis of pathogenesis of this disease. It was concluded that the IgY produced effectively inhibited the dissemination of this bacteria that could be helpful for the treatment and prophylaxis of this disease.

Effects of Maternal Care During Rearing in White Leghorn and Brown Nick Layer Hens on Cognition, Sociality and Fear.

Simple SummaryChickens raised to lay eggs are housed from hatch in groups of animals of the same age, and without maternal care from a broody hen. There are several hybrid lines of hens used in egg farming, each of which show their own behavioral profile. Both the presence (or absence) of a mother hen and genetics may affect cognition, social interactions and fear. In this study, we showed that in our tests, genetics have a strong effect on fear and sociality. Maternal care had very little effect on any of the tests used. The strong effect of genetic background highlights that changes made to increase welfare need to consider the genetics of the chicken in question. The lack of effect of maternal care may indicate that breeds of chickens used in current farming practices were inadvertently selected to respond very little to maternal care.Both genetic background and maternal care can have a strong influence on cognitive and emotional development. To investigate these effects and their possible interaction, White Leghorn (LH) and Brown Nick (BN) chicks, two hybrid lines of layer hen commonly used commercially, were housed either with or without a mother hen in their first five weeks of life. From three weeks of age, the chicks were tested in a series of experiments to deduce the effects of breed and maternal care on their fear response, foraging and social motivation, and cognitive abilities. The LH were found to explore more and showed more attempts to reinstate social contact than BN. The BN were less active in all tests and less motivated than LH by social contact or by foraging opportunity. No hybrid differences were found in cognitive performance in the holeboard task. In general, the presence of a mother hen had unexpectedly little effect on behavior in both LH and BN chicks. It is hypothesized that hens from commercially used genetic backgrounds may have been inadvertently selected to be less responsive to maternal care than ancestral or non-commercial breeds. The consistent and strong behavioral differences between genetic strains highlights the importance of breed-specific welfare management processes.

Identification of hypothalamic genes in associating with food intake during incubation behavior in domestic chicken.

The molecular mechanism underlying in the onset and maintenance of incubation behavior are not fully understood, and it is still unknown the reason why White Leghorn, a layer strain, hens never display incubation behavior. Therefore, to explore specific hypothalamic genes regulating incubation behavior, cap analysis of gene expression (CAGE) were applied to comparison between incubating Silkie and laying White Leghorn hens. In addition, mRNA expression of some differentially expressed genes (DEGs) and melanocortinergic appetite genes including agouti-related peptide (AgRP) and pro-opiomelanocortin (POMC) was also analyzed on Silkie hens under natural anorexia and starvation. The CAGE identified 217 hypothalamic DEGs in incubating Silkie hens, and that of two, transthyretin (TTR) and prolactin-releasing peptide (PrRP), suggested as appetite gene, were markedly up- and down-regulated in incubating hens, respectively. In addition, AgRP and POMC expression also increased in incubating bird. mRNA expression of TTR, PrRP, and appetite genes were not differed significantly by starvation, although TTR mRNA expression was relatively high in fasting hens. Consequently, transcriptome by CAGE identified a number of hypothalamic genes differentially expressed by incubation behavior in Silkie hens. Of these, it is suggested that TTR and PrRP may, at least in part, be related to adaptation to natural anorexia in incubating Silkie chickens.

Effect of cooled perches on performance, plumage condition, and foot health of caged White Leghorn hens exposed to cyclic heat

We examined the effects of water-chilled perches as cooling devices on hen performance during 2 summers using daily cyclic heat. White Leghorns, 17 wk of age, were assigned to 36 cages arranged into 6 banks. The banks were assigned to cooled perches, air perches, and no perches resulting in 2 replicate banks and 12 cages per treatment. Chilled water (10°C) was circulated through the cooled perches during heat episodes. Daily cyclic heat of 35°C was applied from 0600 to1800 h with a lowering of temperature to 28°C from 1800 to 0600 h during the 2014 and 2015 summers when hens were 21 to 35 and 73 to 80 wk of age, respectively. Mortality and egg production were recorded daily. Feed utilization, egg weight, and shell quality traits were measured at 4-wk intervals during the heat episodes and at 8-wk intervals during thermoneutrality. Body weight was determined at 17, 35, 72, and 80 wk of age and physical condition at 80 wk of age. At several ages during the heat episodes, cooled perch hens had increased egg production (P < 0.0001) and feed usage (P < 0.04) as compared to both air perch and control hens. The cooled perch hens had higher BW at 35 and 72 wk of age (Ptreatment*age = 0.03) and lower cumulative mortality (P = 0.02) than control hens but not air perch hens. Eggs from cooled perch hens had overall heavier weights (P < 0.0001) and higher breaking force (P < 0.0001) than eggs from the other two group hens. Greater eggshell percentage (Ptreatment*age = 0.03) and eggshell thickness (Ptreatment*age = 0.01) occurred at some ages during the 2 heat episodes as compared to the other 2 treatments. Nail length, feet hyperkeratosis, and overall feather score were similar among treatments. These results indicate that cooled perch ameliorates the negative effects of heat stress on egg traits and performance without influencing the physical condition of hens.

Effect of cooled perches on physiological parameters of caged White Leghorn hens exposed to cyclic heat

We assessed the effects of water-chilled perches as a cooling device on the physiological parameters of caged laying hens exposed to 2 cyclic heating episodes. White Leghorns, 17 wk of age, were randomly assigned to 36 cages of 6 banks placed in the same room. Each bank was randomly assigned to 1 of 3 treatments: cooled perch (CP), air perch (AP), and no perch (CTRL) resulting in 2 replicate banks and 12 cages per treatment. Chilled water (10°C) circulated through the CP during heat periods when hens were 21 wk to 35 wk and 73 wk to 80 wk of age, respectively. During the heating episodes, hens were submitted to a daily cyclic temperature regimen of 35°C (0600 h to 1800 h) and 28°C (1800 h to 0600h). Rectal temperature, packed cell volume, heterophil to lymphocyte (H/L) ratio, and plasma levels of triiodothyronine (T3), thyroxine (T4), interleukin (IL)-6, IL-10, immunoglobulin (Ig) Y, interferon (IFN)-γ, and heat shock protein (HSP) 70 were measured on the last day of the 2 heating episodes. At the end of the first heating episode, CP hens had lower rectal temperature (P = 0.02) than both AP and CTRL hens. The CP hens also had lower HSP 70 (P = 0.04) than CTRL hens but not AP hens. At the end of the second heating episode, the CP hens had lower rectal temperature (P = 0.02) and circulating H/L ratio (P = 0.01) than both AP and CTRL hens. The CP hens also had higher levels of T3 (P = 0.002) and T3/T4 ratio (P = 0.0006) than CTRL hens but not AP hens, with a greater packed cell volume than AP hens (P = 0.02) but not CTRL hens. Cytokines and IgY levels were similar among treatments. These results indicate that CP hens were better able to cope with cyclic heat stress than CTRL and sometimes AP hens as noted by the beneficial effects on rectal temperature, thyroid activity, HSP, and H/L ratio.

Efficient Production of Human Norovirus-Specific IgY in Egg Yolks by Vaccination of Hens with a Recombinant Vesicular Stomatitis Virus Expressing VP1 Protein.

Human norovirus (HuNoV) is responsible for more than 95% of outbreaks of acute nonbacterial gastroenteritis worldwide. Despite major efforts, there are no vaccines or effective therapeutic interventions against this virus. Chicken immunoglobulin Y (IgY)-based passive immunization has been shown to be an effective strategy to prevent and treat many enteric viral diseases. Here, we developed a highly efficient bioreactor to generate high titers of HuNoV-specific IgY in chicken yolks using a recombinant vesicular stomatitis virus expressing HuNoV capsid protein (rVSV-VP1) as an antigen. We first demonstrated that HuNoV VP1 protein was highly expressed in chicken cells infected by rVSV-VP1. Subsequently, we found that White Leghorn hens immunized intramuscularly with rVSV-VP1 triggered a high level of HuNoV-specific yolk IgY antibodies. The purified yolk IgY was efficiently recognized by HuNoV virus-like particles (VLPs). Importantly, HuNoV-specific IgY efficiently blocked the binding of HuNoV VLPs to all three types (A, B, and O) of histo-blood group antigens (HBGAs), the attachment factors for HuNoV. In addition, the receptor blocking activity of IgY remained stable at temperature below 70 °C and at pH ranging from 4 to 9. Thus, immunization of hens with VSV-VP1 could be a cost-effective and practical strategy for large-scale production of anti-HuNoV IgY antibodies for potential use as prophylactic and therapeutic treatment against HuNoV infection.

Northern fowl mite infestation affects the nocturnal behavior of laying hens

The northern fowl mite (Ornithonyssus sylviarum) is a key pest for caged laying hens. High infestation levels can lead to anemia, reduced production, and mortality. Although the mites cause skin irritation and thus likely affect resting behavior, the nocturnal behavior of infested chickens has not yet been studied. We investigated the impact of mite infestation on nighttime behavior of 16 beak-trimmed White Leghorn hens. The hens were housed individually in wire cages. They were experimentally inoculated with approximately 35 mites at 25 weeks of age and observed for the behaviors dozing, sleeping, preening and being active. Continuous observations were made from video recordings taken from 22:00 h until 06:00 h for two consecutive nights at pre-infestation week 0 and post-infestation weeks 3, 5 and 7. Mite infestation levels were measured weekly on an 8-point scale (0 (no mites) to 7 (≥10,000 mites per hen)). For statistical analyses with linear mixed models, mite infestation levels were categorized as score 0 (no mites), 3–4 (51–500), 5 (501–1000) and 6–7 (>1000). Higher levels of mite infestation were associated with hens spending less time dozing (P < 0.001) and more time preening (P < 0.001) and being active (P = 0.012). Dozing decreased from 90% of the observed time for mite score 0 to 76% for score 6–7. Preening increased from 2% (score 0) to 9% (6–7) and time spent being active increased from 1% (0) to 7% (6–7). Mite infestation increased the number of uninterrupted bouts of all behaviors (P ≤ 0.020), especially dozing and preening (P < 0.001), suggesting restlessness in the mite-infested hens due to irritation and itching. The mite-infested hens’ increased nocturnal activity, including preening, as well as the fragmentation of behavioral activities together with decreased dozing, indicate disturbed resting behavior and suggest a reduction in the welfare of mite-infested hens.

Investigating the genetic determination of clutch traits in laying hens

Clutch traits were proposed as a more detailed description of egg-laying patterns than simple total egg production. In this study, egg production of 23,809 Rhode Island Red (RIR) and 22,210 White Leghorn (WL) hens was described in terms of number of clutches, average and maximum clutch size, age at first egg, total saleable egg production, and percentage of egg defects. Genetic parameters were estimated using a six-trait animal model. Of the phenotyped birds, 1433 RIR hens and 1515 WL hens were genotyped with line specific 50K Affymetrix Axiom single nucleotide polymorphism chips to perform genome-wide association analyses. Moderate heritabilities were estimated for clutch traits of 0.20 to 0.42 in the RIR line and 0.29 to 0.41 in the WL line. Average and maximum clutch size was positively genetically correlated with total saleable egg number in both lines. Genome-wide association analysis identified seven regions that were associated with egg production in the RIR line and 12 regions in the WL line. The regions identified were line and trait specific, except for one region on chromosome 6 from 28 to 29 Mb that influenced number of clutches and maximum and average clutch size in WL hens. Regions associated with egg production identified here overlapped with 260 genes, with some strong positional candidates based on gene ontology including WASH1, which is involved in oocyte maturation, NPVF, involved in regulation of follicle-stimulating hormone secretion, and FOXO3, involved in oocyte maturation and ovulation from the ovarian follicle. Confirmation of the role of these genes in regulation of egg production pattern will require further studies.

How does red light affect layer production, fear, and stress?

Light-emitting diode (LED) light bulbs are becoming more prevalent in layer production as unlike CFLs they are dimmable and are even more energy-efficient than CFLs. There is also discussion on whether the spectrum of light that is produced by the bulb can affect production, stress, and behavior of laying hens. To investigate if differences between how the bulb that produce different wavelengths of light affect these factors, we raised White Leghorn hens under either a bulb that produced white light with the addition of red light (Once, Inc, AgriShift MLL; RED) or a bulb that produced only white light (Overdrive, L10NA19DIM 3000K; WHITE). Each treatment consisted of 36 White Leghorn hens, and the experiment was replicated three times for a total of 108 hens per treatment. Production parameters including % hens in lay, feed conversion, average egg weight, total eggs per hen, eggshell breaking strength, and Haugh units were measured. Hen fear response during tonic immobility and inversion was documented at 3 time points during the study (18, 42, and 72 wk of age). Stress susceptibility was also quantified using plasma corticosterone, heterophil to lymphocyte ratio, and composite asymmetry score at the same time points as the fear testing. No production parameters were affected by lighting type (P > 0.05). Lighting type did not affect tonic immobility or inversion response (P > 0.05). By 42 wk of age and continuing on until 72 wk of age, the RED treatment had lower plasma corticosterone concentrations, lower heterophil to lymphocyte ratios, and lower composite asymmetry scores than the WHITE treatment (P < 0.05). The results indicate that including red light in the spectrum of light layers are reared under can lower stress susceptibility but had no effect on fear response or production parameters when compared to white light.

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.

Effects of Dietary Supplementation of Black Cumin, Garlic and Turmeric on the Production Performance and Egg Quality of White Leghorn Hens

This study was designed to determine the effects of dietary supplementation of black cumin (Nigella sativa), garlic (Allium sativa) and turmeric (Curcuma longa) on the production performance and egg quality in laying hens. A total of 180, 26-weeks old White Leghorn layers were randomly assigned into nine dietary treatments each with four replicates having 5 birds in each, and reared for 12 weeks from 28 to 39 weeks of age. The experimental diets were prepared by supplementing basal diet (T1) with an antibiotic (Enramycin @ 2.5 g per quintal of feed) feed additive (T2), 1% black cumin powder (T3), 1% garlic powder (T4), 1% turmeric powder (T5), 1% mixture of black cumin and turmeric in equal proportion (T6), 1% mixture of black cumin and garlic in equal proportion (T7), 1% mixture of garlic and turmeric in equal proportion (T8) and 1% mixture of black cumin seed, garlic and turmeric in equal proportion (T9). Results indicated a significantly (P<0.05) higher egg production (87.14%) and egg weight (55.85g) in T9 group of birds with the best egg quality. Egg shell quality and organoleptic characteristics of eggs was not affected by dietary treatments. It is concluded that supplementation of one percent equi-proportional mixture of black cumin, garlic and turmeric powder in the diet not only influenced the egg production and egg quality but helped in lowering egg yolk cholesterol and triglycerides during first phase of laying period..

Productivity, reproduction and welfare status of White Leghorn hens under cage and floor housing systems

At 18th week, a total of 450 WLH layer birds from a single hatch were randomly assigned into three treatment groups viz. individual cage, colony cage and floor housing. The performance of hens with regards to sexual maturity, hen-day egg production, egg qualities and welfare parameters in three different housing conditions up to 36 wk of age were assessed. There were significant differences (P<0.05) in the welfare status regarding feather conditions, claw length, gait scores and tonic immobility of the birds between the managemental conditions. While significantly higher (P<0.05) fearful response and time for first peck (response to novel object test) was observed in individual cage layers than the floor and colony birds. The ASM was lower in individual cages (126.76±3.64d) than floor (131.11±13.40d). The hen day egg production till 20th week was higher in colony ages than the floor. During 28–32 weeks individually caged layers had significantly higher hen day egg production (P<0.05) than the colony or floor reared layers. However, during 32–36 weeks (peak summer) the colony reared layer had more egg production (P<0.01) than the colony or floor reared layers. There were significantly difference (P<0.01) in the yolk weight, yolk index, albumin index and Haugh unit between the housing system. The yolk colour was also significantly (P<0.05) darker in individual and colony cages compared to floor reared birds. The present indicates that the WLH layers showed better welfare status when reared on floor but production performance and egg quality was superior in cage type housing system.

Effects of different litter substrates and induced molt on production performance and welfare quality parameters of white Leghorn hens housed in multi-tiered aviary system.

More than 90% of the commercial egg production in the United States is pledged to be in cage-free systems by 2025. Management practices like induced molting and litter area management have come under scrutiny because of the housing system change. The aim of this study was to determine the welfare and production implications of different litter substrates and also evaluate induced molting of hens in a cage-free system. Bovan White hens were housed in a multi-tier aviary system with daily access to open litter area of either Astroturf (AT), wood shavings (SH), or straw (ST) and bare concrete floor (CO) serving as control. At 68 wk of age, molt was induced in half of the hens whereas the other half continued without molting to 116 wk. Production and welfare parameters were measured periodically throughout first and second cycles. Litter substrate did not influence hen-day production and case-weight measurements. However, CO had the lowest total number of eggs produced during the first cycle (P < 0.05). Hen-day percentage was approximately 14% greater in molted hens during the second cycle with egg case weight being heavier in non-molt hens toward the end of second cycle (P < 0.05). The only welfare parameter influenced by litter substrate during the first cycle was a greater crop feather loss in AT than ST at mid-lay (P < 0.05). Keel deformations increased with age irrespective of the litter substrate with 91.5% of palpated hens having keel deformations at the end of first cycle (P < 0.05). Molting did not influence the keel palpation and footpad scores whereas frequency of moderate comb wound was greater in molt hens during molt (P < 0.05). Severe feather loss was seen in non-molt hens during the second cycle (P < 0.05). Litter substrate does not affect production and physical parameters of welfare of hens in a multi-tier aviary system. Additionally, induced molting can be successfully carried out in the multi-tier cage-free system.

Preparation and Application of Egg Yolk Antibodies Against Chinese Sacbrood Virus Infection.

Chinese sacbrood virus (CSBV) infects Apis cerana larvae, resulting in the inability of the larvae to pupate and their consequent death, which may pose a serious threat to entire colonies. As there is no effective medical treatment for CSBV infections, further studies are necessary. In this study, an effective treatment for CSBV is described, based on a specific immunoglobulin Y (IgY) from egg yolk against CSBV. The inactivated vaccine was produced by ultracentrifugation and formalin treatment, using CSBV purified from a natural outbreak. The specific IgY was produced by immunization of white leghorn hens with the vaccine. An enzyme-linked immunosorbent assay using purified CSBV as the coating antigen revealed that the anti-CSBV IgY titer began increasing in the egg yolk on the 14th day post-immunization, reaching a peak on day 42, and anti-CSBV IgY remained at a high level until day 91. IgY isolated from the combinations of egg yolk collected between days 42–91 was purified by PEG and ammonium sulfate precipitation. In three repeated protection experiments using A. cerana larvae inoculated with CSBV, the survival rate of larvae was more than 80%, and the titer of anti-CSBV IgY was more than 25 and 24 when the larvae were fed IgY 24 h after and before inoculation with CSBV, respectively. Therefore, 400 colonies infected with CSBV were treated by feeding sugar containing IgY solutions with an antibody titer of 25, and the cure rate was 95–100%. Three hundred susceptible colonies were protected by feeding the larvae with sugar containing IgY solutions with an antibody titer of 24, and the protection rate was 97%. The results clearly suggest that a specific IgY was obtained from hens immunized with an inactivated-CSBV vaccine; this may be a novel method for controlling CSBV infection.

Dietary phytase supplementation during peak egg laying cycle of White Leghorn hens on nutrient utilization and functional gene mRNA expression in duodenum and kidney

ABSTRACTSeventy-five White Leghorn hens during peak egg laying cycle were randomly divided into 5 groups: 1 group with 0.32% NPP (control), 2 groups with 0.24% NPP and laboratory (T1) or commercial (T2) phytase (250 FTU/kg feed), and 2 groups with 0.16% NPP and laboratory produced (T3) or commercial (T4) phytase (500 FTU/kg feed) from 23 to 40 weeks of age. The results indicated T2 group had the lowest (P > 0.05) bone ash, followed by similar ash content in T1, T3 and control groups. Mineral concentration (Ca, P, zinc and manganese) in the bone was not affected (P > 0.05) by variation in dietary phytase and NPP level. In duodenum, NaPiIIb was up-regulated (P < 0.05) in T2 and T3, whereas Calbindin 1 (CALB1) was up-regulated (P < 0.05) only in T3. In kidney, expression of NaPiIIa and CALB1 were down-regulated (P < 0.05) in all groups. The data demonstrated that 250 FTU/kg laboratory phytase supplementation in feed was enough for replacing 50% of inorganic P and 500 FTU/kg commercial phytase capable of replacing 100% of inorganic P. The up-and down-regulation of NaPiIIb, NaPiIIa and CALB1 genes in treatment groups was independent of phytase source and NPP level in feed.

Production and Evaluation of Immunoglobulin Y Anti-Brucella abortus (Vaccinal Strain B19)

Background: The immunoglobulin Y is a principal antibody current in the blood of hens, which are transferred from the maternal blood serum to the egg yolk. The extraction of IgY from the egg yolk apply animal welfare when compared to the extraction of IgG, reducing the number of animals and prevent a bleeding of hens through the extraction of the IgY from eggs, besides that IgY presenting high specificity for antigenic binding. The objective of this study was to produce specific polyclonal IgY antibodies anti-Brucella abortus by immunizing hens with B19 vaccine and evaluate their reactivity through Buffered Acidified Plate Antigen (BAPA), 2-Mercaptoethanol (2-ME) and indirect ELISA diagnostic tests.Materials, Methods &amp; Results: Four 25-week-old White Leghorn hens were immunized, two of them comprising the control group (Group 1) with phosphate-buffered saline (PBS) with adjuvant, and the others two immunized with B19 vaccine (Brucella abortus vaccine strain B19), representing the Group 2. The immunizations occurred six times with a 15-day interval between each. Blood samples were taken biweekly (seven times); and daily, the eggs were collected for 13 weeks, the first collection of blood and eggs, performed one week before the first immunization of each group. The IgY was purified from egg yolk, using the method of dilution in acid water and precipitation with ammonium sulfate for delipidation. BAPA, 2-ME and ELISA tests performed to verify the specificity of IgY confirmed the reactivity of polyclonal antibodies specific to the antigen used both in blood serum samples and in the purified egg yolks. The hens from the control group did not present reactivity in the diagnostic tests used, which was already expected, since no antigen was used in any of their immunizations. Hens immunized with the Brucella abortus B19 vaccine produced detectable reactive antibodies in the three tests used on blood serum and IgY samples extracted from the egg yolk. In Group 2 (vaccine B19), blood serum samples started to react one week after the first inoculation, and the IgY samples extracted from the egg yolk were reagent two weeks after serum IgY appear reactivity, showing the transfer of specific antibodies to the egg yolk, was late.Discussion: Although the transfer of serum Igy to egg yolk was late when compared to others authors which found that the transovarian passage of immunoglobulin Y occurred in approximately three to six days after IgY being detected in blood serum, the results of this study showed the occurrence of the transfer of blood serum IgY anti-Brucella abortus to egg yolk of hens immunized with B19 vaccine, the same found by others researches found the same results with others antigens. Thus, it can be concluded that immunoglobulins Y produced in this study can be used as specific antibodies in diagnostic tests for the detection of the Brucella abortus antigen, in addition, this process guarantees the welfare of the animal, since it avoids bleeding and it is possible to obtain high concentrations of antibodies directly from the hen egg, which is a great advantage, because IgY can be easily isolated from the egg yolk by the precipitation technique discarding the need of invasive and painful procedures that involve bloody interventions to obtain the serum antibodies like occur in mammals for extraction of IgG.

Influencia del hidrolizado de proteínas en el comportamiento bioproductivo en gallinas de la línea L1 White Leghorn

The objective of this study was to evaluate the influence of protein hydrolysates (PH), as a nutritional supplement, in the bioproduction performance of White Leghorn hens. Thirty-nine-week old light line hens were assessed during six weeks. Two treatments (T) were designed involving 320 hens each (three replications of 40 hens each). In T1, each bird received 2 ml of PH daily; the birds in T2 were not offered the product. The following variables were controlled: bioproduction (total egg production, egg-laying percentage, total feed intake, mass conversion, viability, and caused mortality); incubation indicators (eggs to plant, incubation percentage, hatchability, and top quality chicks) and; quality (feed intake by top quality chicks, and top quality chicks per hen). The hens that received the PH showed significant differences in the laying, incubation, and hatchability percentage, as well as mass conversion, and the egg to plant ratio. They showed better performance in quality indicators. It is concluded that the use of PH in light line hens improves their bioproduction performance, as well as the indicators of to incubation, egg to plant ratio, and hatchability; its use also reduces by approximately 100 grams the necessary food intake to obtain top quality chicks.