White Leghorn Research Articles

Parent-of-origin has no detectable effect on survival days of Marek's disease virus infected White Leghorns

Marek's Disease (MD) is a neoplastic disease of chickens and remains as a chronic infectious disease that threatens the poultry industry. Improving genetic resistance to MD in poultry is an important long-term goal, which would significantly augment the current control measures against MD and eventually reduce the annual economic loss. In this study, survival patterns of F2 birds from 2 reciprocal crosses were compared to examine possible difference in survival between the reciprocal crosses in response to MD virus (MDV) challenge. A total of 246 and 224 F2 chicks derived from reciprocal crosses of lines 63 × 72 and lines 72 × 63, respectively, were sampled from an MDV challenge trial and survival days were recorded from the MDV-inoculation date to the end of experiment. Statistical analyses, including Principal Component Analysis (PCA) followed by a cox-regression model, showed there was no significant difference in survival days between reciprocal crosses (P > 0.05). To the best of our knowledge, this is the first MD survival study on reciprocal crosses of 2 genetically diversified lines of chickens differing in MD resistance. This report documented the experimental evidence that the genetic lineage of grandparental (maternal or paternal) effect on survival days was minimal, if present at all.

Chicken germplasms and their conservation in Bangladesh: A review

The present article addresses the scenario of chicken genetic resources, their production and reproduction performances and their conservation in Bangladesh. The chickens, among other poultry species available in the country, are the most versatile component for meat and egg production. The chicken germplasms available in the country are indigenous, exotic, crossbred, and commercial hybrid. The indigenous chicken population is comprised of Non-descript Desi (ND), Naked Neck (NN), Aseel (AS), Hilly (H), Native Dwarf and Jungle Fowl etc. The exotic chicken such as, White Leghorn (WL), White Rock (WR), White Cornish (WC), Rhode Island Red (RIR), Australorp, Fayoumi, Barred Plymouth Rock (BPR) etc. are imported mostly to upgrade the indigenous stock. The crossbred of different chickens are used in the country in intensive, semi-intensive and scavenging management system. The commercial hybrid such as grandparent stock (GP), parent stock (PS), commercial broiler, commercial layer etc. has got most popularity for meat and egg production in the country. Conservation and improvement program of endangered native chicken such as Aseel and Native Dwarf chicken should be taken both in-situ or ex-situ in vivo by public sector/research institutes/universities.
 SAARC J. Agri., 17(1): 119-134 (2019)

Survivability, immunity, growth and production traits in indigenous and White Leghorn breeds of chicken

ABSTRACT 1. The survivability, innate and adaptive immunity, growth and production traits up to 72 weeks of age were determined in Ghagus, Nicobari (unimproved indigenous) and White Leghorn (WLH) breeds and the study investigated links between innate and adaptive immunity and survivability and production traits. 2. At 20 and 40 weeks of age, there was a significant effect of breed on innate immunity assessed by measuring titres of natural antibody (NAb) binding to rabbit red blood cells (RRBC) and adaptive immunity assessed by measuring specific antibody titre (SpAb) to Newcastle disease virus. 3. Highest survivability was in WLH (91.6%) followed by Nicobari (87.1%) and Ghagus (82.9%) breeds. Growth traits at different ages were higher (P< 0.001) in Ghagus followed by WLH and Nicobari breeds. Egg production up to 72 weeks was higher (P < 0.001) in WLH followed by Nicobari and Ghagus breeds, whereas egg weight at different ages was higher (P < 0.001) in WLH than Ghagus and Nicobari breeds. 4. NAb titres measured at 20 weeks were significantly (P = 0.002) associated with the survivability of hens during 20 to 72 weeks of age. Breed-wise analysis showed a significant (P = 0.019) association between NAb titres at 20 weeks and survivability in the Ghagus breed. Furthermore, NAb titres at 20 weeks were higher in hens which survived to 72 weeks compared with those that died (P = 0.002). 5. Measuring NAb titres to RRBC is quick, economical and simple. This method has potential to be used in a breeding programme to increase survivability of laying hens.

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.

Genetics of male reproductive performance in White Leghorns

The ability to produce viable progeny is a complex trait, involving both male and female components. In poultry, mating ratios are usually 1 male to 6 to 12 females. Consequently, the impact of male reproductive failure is much greater than that for a female. In this study, the genetic determination of male reproductive performance, by natural mating and artificial insemination (AI), was evaluated. Semen quality was studied in 1,575 pre-selected (using a selection index of multiple egg production and quality traits) White Leghorn males of a single pure line from multiple generations. A subset of individuals with satisfactory semen quality (based on sperm count and motility) were further tested for subsequent fertility and hatchability. Genetic parameters for fertility (FER), hatch of fertile (HOF), hatch of set (HOS), sperm motility (SM), sperm count (SC), and fertility using AI (FER-AI) were estimated using single- and multi-trait animal models, with generation as fixed effect. Selected birds were genotyped using the 600K Affymetrix SNP chip. Genomic data were analyzed with the BayesB method. FER, HOS, and HOF were highly correlated, both genetically (0.82 to 0.99) and phenotypically (0.28 to 0.99), but genetic correlations with semen quality traits were not strong (0.05 to 0.43) and phenotypic correlations varied between generations (-0.13 to 0.14). Birds used for fertility and hatchability tests were pre-selected based on SM and SC, which could contribute to the lack of strong correlations between these traits (due to truncation of the distribution). Based on pedigree information, low to moderate heritabilities were estimated for reproductive traits (0.08 to 0.21). Markers explained a low proportion of phenotypic variance (0.04 to 0.15), probably due to stringent selection of genotyped individuals and the limited training set size. No genes with large effects were identified. Genomic estimated breeding values were more accurate than pedigree-based estimates but only for HOF and FERT-AI. Despite low estimates of accuracy in validation, genetic trends were positive for all analyzed traits. In conclusion, continued long-term selection can result in genetic improvement of reproductive performance of roosters.

Genetic variation and potential for genetic improvement of cuticle deposition on chicken eggs

BackgroundThe cuticle is an invisible glycosylated protein layer that covers the outside of the eggshell and forms a barrier to the transmission of microorganisms. Cuticle-specific staining and in situ absorbance measurements have been used to quantify cuticle deposition in several pure breeds of chicken. For brown eggs, a pre-stain and a post-stain absorbance measurement is required to correct for intrinsic absorption by the natural pigment. For white eggs, a post-stain absorbance measurement alone is sufficient to estimate cuticle deposition. The objective of the research was to estimate genetic parameters and provide data to promote adoption of the technique to increase cuticle deposition and reduce vertical transmission of microorganisms.ResultsFor all pure breeds examined here, i.e. Rhode Island Red, two White Leghorns, White Rock and a broiler breed, the estimate of heritability for cuticle deposition from a meta-analysis was moderately high (0.38 ± 0.04). In the Rhode Island Red breed, the estimate of the genetic correlation between measurements recorded at early and late times during the egg-laying period was ~ 1. There was no negative genetic correlation between cuticle deposition and production traits. Estimates of the genetic correlation of cuticle deposition with shell color ranged from negative values or 0 in brown-egg layers to positive values in white- or tinted-egg layers. Using the intrinsic fluorescence of tryptophan in the cuticle proteins to quantify the amount of cuticle deposition failed because of complex quenching processes. Tryptophan fluorescence intensity at 330 nm was moderately heritable, but there was no evidence of a non-zero genetic correlation with cuticle deposition. This was complicated furthermore by a negative genetic correlation of fluorescence with color in brown eggs, due to the quenching of tryptophan fluorescence by energy transfer to protoporphyrin pigment. We also confirmed that removal of the cuticle increased reflection of ultraviolet wavelengths from the egg.ConclusionsThese results provide additional evidence for the need to incorporate cuticle deposition into breeding programs of egg- and meat-type birds in order to reduce vertical and horizontal transmission of potentially pathogenic organisms and to help improve biosecurity in poultry.

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.

Alteration of Serum Biochemical Parameters Due to Cow Urine Distillate in Triazophos Intoxicated White Leghorn Cockerels

In this study twenty five white leghorn male chicken of one month and one week old weighing about 244 to 248 gms were procured and were kept at Instructional Poultry Farm Nagla, Pantnagar. The birds in poultry shed were reared in deep litter system, were kept under standard managemental conditions and were randomly divided into five groups of 5 birds each. After one week of adaptation period, different doses of Triazophos were administered via feed at 2.5, 5 ppm level and cow urine distillate was administered via feed. At 2.5, 5 ppm level and cow urine distillate was administered through drinking water at the rate of 1ml per bird per day to groups G4, G5 respectively for 100 days daily. White leghorn cockerels are layers not broilers and can sustain for a period of 2-3 years. The birds of group “G1” served as control. After every 25 days blood was taken from each bird including day zero for study of different. viz. glucose, total protein, albumin, globulin, cholesterol, creatinine, uric acid, alanine aminotransferase ALT and aspartate aminotransferase AST. Total protein, Albumin, globulin, parameters showed significant (P<0.01) decrease while in Cholesterol, Creatinine, Glucose, Uric Acid, ALT, AST showed a significant increase (P<0.01) in different doses of Triazophos treated birds in comparison to birds of control group while a significant increase (P<0.01) in Total protein, Albumin, globulin and a significant decrease (P<0.01) Cholesterol, Creatinine, Glucose, Uric Acid, ALT, AST was observed in cow urine treated groups (G4, G5) as compared to non cow urine treated groups (G2 and G3).

Feather colour affects the aggressive behaviour of chickens with the same genotype on the dominant white (I) locus.

Aggression in chickens is a serious economic and animal welfare issue in poultry farming. Pigmentation traits have been documented to be associated with animal behaviour. Chicken pecking behaviour has been found to be related to feather colour, with premelanosome protein 17 (PMEL17) being one of the candidate genes. In the present study, we performed a genotypic and phenotypic association analysis between chicken plumage colour (red and white) and aggressive behaviour in an F1 hybrid group generated by crossing the autosomal dominant white-feathered breed White Leghorn (WL) and the red-feathered breed Rhode Island Red (RIR). In genetic theory, all the progeny should have white feathers because WL is homozygous autosomal dominant for white feathers. However, we found a few red-feathered female chickens. We compared the aggressiveness between the red and white females to determine whether the feather colour alone affected the behaviour, given that the genetic background should be the same except for feather colour. The aggressiveness was recorded 5 days after sexual maturity at 26 weeks. Generally, white plumage hens showed significantly higher aggressiveness compared to the red ones in chasing, attacking, pecking, and threatening behaviour traits. We assessed three candidate feather colour genes—PMEL17, solute carrier family 45 member 2 (SLC45A2), and SRY-box 10 (SOX10)—to determine the genetic basis for the red and white feather colour in our hybrid population; there was no association between the three loci and feather colour. The distinct behavioural findings observed herein provide clues to the mechanisms underlying the association between phenotype and behaviour in chickens. We suggest that mixing red and white chickens together might reduce the occurrence of aggressive behaviours.

Experimental Infection and Transmission of Newcastle Disease Vaccine Virus in Four Wild Passerines.

Our prior work has shown that live poultry vaccines have been intermittently isolated from wild birds sampled during field surveillance studies for Newcastle disease virus (NDV). Thus, we experimentally investigated the susceptibility of four native agriculturally associated wild bird species to the NDV LaSota vaccine and evaluated the shedding dynamics, potential transmission from chickens, and humoral antibody responses. To test susceptibility, we inoculated wild-caught, immunologically NDV-naïve house finches (Haemorhous mexicanus; n = 16), brown-headed cowbirds (Molothrus ater; n = 9), northern cardinals (Cardinalis cardinalis; n = 6), and American goldfinches (Spinus tristis; n = 12) with 0.1 ml (106.7 mean embryo infectious doses [EID50/ml]) of NDV LaSota vaccine via the oculo-nasal route. To test transmission between chickens and wild birds, adult specific-pathogen-free white leghorn chickens were inoculated similarly and cohoused in separate isolators with two to five wild birds of the species listed above. This design resulted in three treatments: wild bird direct inoculation (five groups) and wild bird exposure to one (two groups) or two inoculated chickens (six groups), respectively. Blood and oropharyngeal and cloacal swabs were collected before and after infection with the live vaccine. All wild birds that were directly inoculated with the LaSota vaccine shed virus as demonstrated by virus isolation (VI). Cardinals were the most susceptible species based on shedding viruses from 1 to 11 days postinoculation (dpi) with titers up to 104.9 EID50/ml. Although LaSota viruses were shed by all inoculated chickens and were present in the drinking water, most noninoculated wild birds cohoused with these chickens remained uninfected for 14 days as evidenced by VI. However, one American goldfinch tested positive for vaccine transmission by VI at 7 dpi and one house finch tested positive for vaccine transmission by real-time reverse-transcription PCR at 13 dpi. Only one directly inoculated cowbird (out of three) and two cardinals (out of two) developed NDV-specific hemagglutination inhibition antibody titers of 16, 16, and 128, respectively. No clinical signs were detected in the chickens or the wild birds postinoculation.

Inheritance patterns of the transcriptome in hybrid chickens and their parents revealed by expression analysis

Although many phenotypic traits of chickens have been well documented, the genetic patterns of gene expression levels in chickens remain to be determined. In the present study, we crossed two chicken breeds, White Leghorn (WL) and Cornish (Cor), which have been selected for egg and meat production, respectively, for a few hundred years. We evaluated transcriptome abundance in the brain, muscle, and liver from the day-old progenies of pure-bred WL and Cor, and the hybrids of these two breeds, by RNA-Seq in order to determine the inheritance patterns of gene expression. Comparison among expression levels in the different groups revealed that most of the genes showed conserved expression patterns in all three examined tissues and that brain had the highest number of conserved genes, which indicates that conserved genes are predominantly important compared to others. On the basis of allelic expression analysis, in addition to the conserved genes, we identified the extensive presence of additive, dominant (Cor dominant and WL dominant), over-dominant, and under-dominant genes in all three tissues in hybrids. Our study is the first to provide an overview of inheritance patterns of the transcriptome in layers and broilers, and we also provide insights into the genetics of chickens at the gene expression level.

Genome-wide association studies targeting the yield of extraembryonic fluid and production traits in Russian White chickens

BackgroundThe Russian White is a gene pool breed, registered in 1953 after crossing White Leghorns with local populations and, for 50 years, selected for cold tolerance and high egg production (EL). The breed has great potential in meeting demands of local food producers, commercial farmers and biotechnology sector of specific pathogen-free (SPF) eggs, the former valuing the breed for its egg weight (EW), EL, age at first egg (AFE), body weight (BW), and the latter for its yield of extraembryonic fluid (YEF) in 12.5-day embryos, ratio of extraembryonic fluid to egg weight, and embryo mass. Moreover, its cold tolerance has been presumably associated with day-old chick down colour (DOCDC) – white rather than yellow, the genetic basis of these traits being however poorly understood.ResultsWe undertook genome-wide association studies (GWASs) for eight performance traits using single nucleotide polymorphism (SNP) genotyping of 146 birds and an Illumina 60KBeadChip. Several suggestive associations (p < 5.16*10− 5) were found for YEF, AFE, BW and EW. Moreover, on chromosome 2, an association with the white DOCDC was found where there is an linkage disequilibrium block of SNPs including genes that are responsible not for colour, but for immune resistance.ConclusionsThe obtained GWAS data can be used to explore the genetics of immunity and carry out selection for increasing YEF for SPF eggs production.

Effect of probiotics on fecal excretion, colonization in internal organs and immune gene expression in the ileum of laying hens challenged with SalmonellaEnteritidis

A study was conducted to evaluate the supplementation of probiotics on Salmonella colonization in the ceca and various internal organs as well as immune response in laying hens challenged with Salmonella enterica serovar Enteritidis (SE). Thirty-two 46-wk-old White Leghorns (W-36) were housed individually in wired laying cages under 16L:8D lighting schedule. Hens were challenged individually with nalidixic acid resistant Salmonella Enteritidis (SENAR) after which time they were grouped into four treatments: T1 = SENAR unchallenged control, T2 = SENAR challenged control, T3 = SENAR challenged + 0.05% probiotics (Lactobacillus plantarum), and T4 = SENAR challenged + 0.1% probiotics. All hens, including T1, were euthanized and sampled for the liver with gall bladder (L/GB), ileum, ovary, spleen, and ceca on 7-days post-infection (dpi). Fecal screening was performed on individual hens at both 3 and 6 dpi. No difference was detected between the treatments in cecal SENAR enumeration, and the mean log 10 cfu/gm of SENAR in the ceca was 3.7 for all three treatments. The prevalence of SENAR was lowest for ovary in all treatments and was highest in the spleen. However, there were no significant differences among the treatments in the internal organs. There was no significant difference in the fecal shedding among the treatments on either 3 or 6 dpi, with incidence of positive feces higher at 3 dpi compared to 6 dpi (100vs. 70% to 80%). SENAR challenge resulted in significant upregulation (P < 0.05) of interleukin (IL)-1β, 6, 10, interferon gamma (IFN-γ), and toll-like receptor (TLR)-4 mRNA expression. Highest level of probiotics resulted in a significant decrease in IFN-γ and elevation of IL-6 and IL-10 gene expression in the ileum. However, IL-1B and TLR-4 gene expression were not different from the SENAR challenge control. This study reveals that there was important regulation of immune genes by probiotics supplementation.

Velogenic newcastle disease virus tissue tropism and pathogenesis of infection in chickens by application of in situ PCR, immunoperoxase staining and HE staining

Limited deep studies are available in the field of early stages of pathogenesis of Newcastle disease virus (NDV) infection and tissue tropism of NDV. In this study, 24 specific pathogen free (SPF) chickens of white leghorn breed were infected with Newcastle disease (ND) by intranasal administration of 10⁵ 50% EID50/0.1 mL of velogenic NDV (vNDV). A second group of 15 chickens were kept as a control group. Chickens were monitored every day to record clinical signs. Infected chickens were euthanized by cervical dislocation at successive times, namely at hours (hrs) 2, 4, 6, 12, days 1, 2, 4, and 6 post-inoculation (pi). Whereas, control group chickens were euthanized on days 0, 1, 2, 4, and 6 pi. Tissues of brain, trachea, lung, caecal tonsil, liver, kidney, spleen, heart, proventriculus, intestine, and thymus were collected, fixed in 10% buffered formalin, embedded in paraffin, and sectioned. HS staining, immunoperoxidase staining (IPS) and in situ PCR were applied. It was concluded that at hr 2 pi, virus seemed to be inclined to trachea and respiratory tract. Meanwhile, it attacked caecal tonsils, intestine and bursa of Fabricus. While primary viraemia was ongoing, virus created footing in kidney and thymus. At hr 4 pi, proventriculus, liver, and spleen were attacked. However, at hr 6 pi, brain and heart were involved. Secondary viraemia probably started as early as hr 12 pi since all collected tissues were positive. Tissue tropism was determined in trachea, caecal tonsil, liver, bursa of Fabricius, intestine, proventriculus, lung, spleen, thymus, kidney, heart, and brain.

Effect of Pullet Vaccination on Development and Longevity of Immunity.

Avian respiratory disease causes significant economic losses in commercial poultry. Because of the need to protect long-lived poultry against respiratory tract pathogens from an early age, vaccination programs for pullets typically involve serial administration of a variety of vaccines, including infectious bronchitis virus (IBV), Newcastle disease virus (NDV), and infectious laryngotracheitis virus (ILTV). Often the interval between vaccinations is only a matter of weeks, yet it is unknown whether the development of immunity and protection against challenge when vaccines are given in short succession occurs in these birds, something known as viral interference. Our objective was to determine whether serially administered, live attenuated vaccines against IBV, NDV, and ILTV influence the development and longevity of immunity and protection against challenge in long-lived birds. Based on a typical pullet vaccination program, specific-pathogen-free white leghorns were administered multiple live attenuated vaccines against IBV, NDV, and ILTV until 16 weeks of age (WOA), after which certain groups were challenged with IBV, NDV, or ILTV at 20, 24, 28, 32, and 36 WOA. Five days post-challenge, viral load, clinical signs, ciliostasis, tracheal histopathology, and antibody titers in serum and tears were evaluated. We demonstrate that pullets serially administered live attenuated vaccines against IBV, NDV, and ILTV were protected against homologous challenge with IBV, NDV, or ILTV for at least 36 weeks, and conclude that the interval between vaccinations used in this study (at least 2 weeks) did not interfere with protection. This information is important because it shows that a typical pullet vaccination program consisting of serially administered live attenuated vaccines against multiple respiratory pathogens can result in the development of protective immunity against each disease agent.

Effect of incremental levels of dietary total sulfur amino acids on performance of white leghorn laying hens fed diets containing guar (Cyamopsis tetragonoloba) meal.

The present study evaluated the potential of increasing dietary levels of the most limiting amino acids such as total sulfur amino acids (TSAA) with respect to mitigating the adverse effects of the inclusion of guar meal (GM) in the diet of WL layers on egg production, feed efficiency and egg weight. In total, 4928 WL (Lohmann L) hens (32 week of age) were randomly allotted to eight treatments with seven replicates of 88 birds. The dietary treatments were a set of four maize-soybean meal based diets containing four graded concentrations of TSAA (5.85, 6.18, 6.51 and 6.84 g kg-1 ) and another set of four diets containing 100 g kg-1 guar meal (GM) with similar concentrations of TSAA. The inclusion of 100 g kg-1 GM in the diet caused a 20%, 23%, 35.5% and 6.7% reduction in egg production, daily egg mass, feed efficiency and egg weight, respectively, when the diet contained 5.85 g kg-1 TSAA. Increasing TSAA levels in GM groups reduced the adverse effects on egg production and feed efficiency 50%, with no effect on egg weight. The TSAA requirement of WL birds fed 10% GM was estimated as 6.28-7.39 g kg-1 diet at different ages. Increasing dietary TSAA to 7.39, 6.28, 6.53 and 6.37 g kg-1 or dTSAA (digestible TSAA) to 6.53, 5.32, 5.80 and 5.63 g kg-1 during 33-36, 37-40, 41-44 and 45-48 weeks of age, respectively, may be an effective and practical strategy for reducing the adverse effects of inclusion of 100 g kg-1 GM in the diet of WL layers. © 2018 Society of Chemical Industry.

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.

Effect of Supplementation of Chromium and Spirulina on Quality and Cholesterol Profile of Chicken Eggs

A trial was conducted for a period of 45 days in factorial (3x3) model to study the effect of three dietary levels of supplemental organic form of chromium (0.0, 1.0 and 2.0 mg/kg) each with three levels of Spirulina (0.0, 1.0 and 2.0 g/kg) in order to produce egg with low cholesterol. Seventy two White Leghorn (WLH) laying hens were randomly divided into nine equal groups and housed in individual cages from where records for each bird were collected. Egg production, feed intake, yolk cholesterol and plasma lipids were evaluated at the end of the experimental feeding. No differences were found in feed intake, egg weight and egg production. Yolk cholesterol showed a dose dependent reduction (P≤0.01) due to supplementation of spirulina. The level of plasma cholesterol, triglyceride, HDL and VLDL as well as blood glucose, mostly followed a similar trend of gradual reduction for interaction of spirulina and chromium, although the values were statistically similar. A combination of spirulina (1g kg−1) and chromium (2 mg kg−1) produced lowest total yolk cholesterol (157.2 mg) with a reduction of more than 35% compared to the content of a normal egg (213 mg). Thus, the combination of spirulina and chromium may be used for production of low cholesterol containing egg without affecting the production performance of laying hens.

Maintaining the predictive abilities of egg freshness models on new variety based on VIS-NIR spectroscopy technique

This research was performed to study calibration model transfer between White Leghorns eggs and Bantam eggs for prediction of egg freshness by visible near infrared (VIS-NIR) spectroscopy. Transmission spectra of the two varieties were acquired in the equatorial region of the eggs. And albumen pH as the freshness evaluating parameter was measured using traditional destructive methods. After outliers were eliminated by Mahalanobis distance combined with principal component analysis (PCA), partial least squares regression (PLSR) with different preprocessing methods was used to develop prediction models. Global updating, direct standardization (DS) and slope/bias correction (SBC) were evaluated to transfer calibration models from one variety to another. The Kennard-Stone (KS) algorithm was used to select standardization samples. White Leghorns eggs and Bantam eggs as the master variety in turn were compared to find superior master variety. Application of the slope/bias correction (SBC) algorithm obtained the best prediction results of albumen pH. And the better slope/bias correction (SBC) transfer performance with a rp of 0.908 and a RMSEP of 0.133 was found when Bantam eggs were as the superior master variety.

Effect of supplementing graded concentrations of non-phytate phosphorus on performance, egg quality and bone mineral variables in White Leghorn layers

ABSTRACT1. An experiment was conducted to determine optimal non-phytate phosphorus (NPP) concentrations for White Leghorn (WL) layers (22–72 weeks) fed diet containing 38 g Ca/kg.2. Eight diets with graded concentrations (1.5–3.25 g/kg in increments of 0.25 g) of NPP were prepared. Each diet was fed to eight pen replicates containing 88 birds in each. Performance data was evaluated in three different phases (phase I-22–37 weeks, phase II-38–53 weeks and phase III-54–72 weeks). Optimum levels of NPP were determined by fitting a quadratic polynomial (QP) regression model.3. Egg production (EP) was not affected (P = 0.059) by the concentration of NPP and interaction between NPP and diet phase was non-significant, indicating that the lowest concentration (1.5 g/kg diet) of NPP used in the study was adequate across the three phases. However, EP was influenced by phase (P < 0.001).4. Optimum concentration of NPP for feed intake (FI) was estimated to be 1.5, 1.71 and 2.40 g/kg diet during phases I, II and III, respectively. FI per egg mass (EM) or feed efficiency (FE) responded quadratically with NPP and also differed significantly between phases. Optimum concentration of NPP for FE during phases I, II and III was 1.5, 2.56 and 2.32 g/kg diet, respectively.5. Egg weight (EW), EM, shell weight and thickness were not affected by NPP concentration although all of these variables (except shell weight) were influenced by phases.6. Breaking strength of tibia and Ca contents in tibia ash were not affected by the concentration of NPP, but bone ash and P contents in tibia ash were influenced (P < 0.001) by NPP. Predicted optimal concentrations of NPP for responses for tibia ash at 44 or 72 weeks, tibia ash P at 44 weeks and tibia ash P at 72 weeks were 1.55, 2.63 and 1.5 g/kg diet, respectively.7. Based on the results, it was concluded that WL layers required 1.5 g, 2.63 g and 2.4 g, respectively/kg diet during phase I, II and III with the calculated daily intake of 137.3, 278.3 and 262 mg NPP/b/d.