Strains Of Laying Hens Research Articles

Egg quality assessment at different storage conditions, seasons and laying hen strains

ABSTRACT Eggs are one of nearly perfect protein foods, offering nutrients of great biological value. However, during storage, egg albumen and yolk components may alter and deteriorate egg quality. Therefore, the aim of this work was to assess egg quality during 9-week storage. Parameters such as Haugh unit, weight loss, egg width and length, specific gravity, yolk and albumen dimensions and their pH were evaluated weekly. A total of 270 eggs (n=5) collected from two different hen strains were evaluated under room (20 to 35 °C in summer; 11.2 to 29.7 °C in autumn) and refrigerated (0 to 5 °C in summer; -3.1 to 6.5 °C in autumn) temperatures. For storage time, an unfolding analysis was accomplished by regression analysis using orthogonal polynomials. As a second approach, principal component analysis (PCA) was performed in order to assess correlations among quality parameters on storage conditions and laying hen strains. By the end of the 9-week storage period, eggs kept under refrigeration presented similar quality parameters to eggs stored at room temperature for only 3 weeks. In contrast, eggs kept at room temperature presented faster degradation from week 1 to 5. No differences on egg quality parameters were noticed between white and brown shells eggs. PCA suggests that better egg quality (first week) was associated mainly with higher egg weight and its specific gravity, Haugh unit and albumen height. Eggs stored at room temperature should be consumed in 2 weeks or refrigerated until 8 weeks, preserving internal quality from farm to retail.

Flock size during rearing affects pullet behavioural synchrony and spatial clustering

Animals are often synchronised in their behaviour, with costs and benefits varying according to group size and the behaviour being performed. Making decisions about optimal allocation and distribution of resources to animals in our care therefore poses theoretical and practical challenges. We investigated group size effects on behavioural synchrony and spatial clustering during daytime in pullets of a commercial laying hen strain reared until 18 weeks of age in groups of 15, 30, 60 and 120 (four replicates of each group size). Feeder, drinker, perch and litter space (i.e. floor space allowance) per bird, were constant across group sizes and all resources were continuously available. Even though the absolute numbers of birds performing the same behaviour at the same time or being located together at the same resource patch increased with increasing group size, the relative degree of synchrony of feeding, drinking, perching and preening across the whole flock decreased exponentially with increasing group size (P<0.001 for all behaviours) as did the relative degree of clustering at the same resource patch (P<0.001 for the same four behaviours). Preening was the most synchronous behaviour (more than twice that of the least synchronised behaviour, perching), and feeding the most clustered in space (three times more clustered than the other behaviours). These results imply that it is more important to provide sufficient resource space for all birds to perform daytime activities simultaneously when kept in the smaller group sizes typical of cages, than in the larger flocks typical of birds kept in floor pens and aviaries.

The Effect of Biduri (Calotropis gigantean) Latex on Meat Quality of Post Laying Hen

The aim of this research was to investigate the effect of biduri (Calotropis gigantean) latex treatment on physical quality and hedonic test of meat of post laying hen. Samples of this research used meat of post laying hen strain Lohman aged 90 weeks. Thigh muscle was used for physical quality and breast muscle for hedonic test. Extract of biduri latex were obtained by cutting and tapping of young stem tissue, and it was centrifuged to obtain crude fluid of biduri latex (supernatant). Variables of this research were pH, cooking loss, tenderness, and water holding capacity (WHC), and hedonic test. Levels of biduri latex were 0, 3, 6 and 9% were measured from weight of the samples and the treatment of biduri latex by smearing on the surface of meat samples. The experimental design of the research used one way randomized design. The data was analyzed by using ANOVA, and differences between treatment means were further analysed using Duncan’s New Multiple Range Test. The effect of biduri latex did not affect on pH, but it significantly affected on cooking loss, WHC, tenderness, and hedonic test (p<0.01). Cooking loss started to decrease in concentration of 6%. Value of WHC and tenderness went up at concentration of 3%. Increasing of meat quality of tenderness of hedonic test, juicy and overall hedonic test started to increase in concentration of 6%, and also flavor on concentration of 3% and 9%. In conclusion, the treatment of biduri latex with concentration of 3% could increase meat quality of meat of post laying hen.

In ovo sexing of chicken eggs by fluorescence spectroscopy.

Culling of day-old male chicks in production of laying hen strains involves several millions of animals every year worldwide and is ethically controversial. In an attempt to provide an alternative, optical spectroscopy was investigated to determine nondestructively in ovo the sex of early embryos of the domestic chicken. The extraembryonic blood circulation system was accessedby producing a window in the egg shell and the flowing blood was illuminated with a near-infrared laser. The strong fluorescence and the weak Raman signals were acquired and spectroscopically analyzed between 800 and 1000nm. The increase of fluorescence intensity between 3.5 and 11.5days of incubation was found to be in agreement with the erythropoietic stages, thus enabling to identify hemoglobin as fluorescence source. Sex-related differences in the fluorescence spectrum were found at day 3.5, and principal component (PC) analysis showed that the blood of males was characterized by a specific fluorescence band located at ∼910nm. Supervised classification of the PC scores enabled the determination of the sex of 380 eggs at day 3.5 of incubation with a correct rate up to 93% by combining the information derived from both fluorescence and Raman scattering. Graphical abstract The fluorescence of blood obtained in ovo by illumination of embryonic vessels with a IR laser displays spectral differences that can be employed for sexing of eggs in early stage of incubation, before onset of embryo sensitivity and without hindering its development into a healthy chick.

Influence of genetic strain and access to litter on spatial distribution of 4 strains of laying hens in an aviary system

Many laying hen producers are transitioning from conventional cages to new housing systems including multi-tier aviaries. Aviary resources, such as litter areas, are intended to encourage hens’ expression of natural behaviors to improve their welfare. Little research has examined the influence of laying hen strain on distribution and behavior inside aviaries, yet differences could influence a strain's suitability for an aviary design. This research examined how laying hens of 4 strains (Hy-Line Brown [HB], Bovans Brown [BB], DeKalb White [DW], and Hy-Line W36) distributed themselves among 3 enclosed aviary tiers and 2 litter areas at peak lay (25 to 28 wk of age) and after gaining access to litter on the floor (26 wk). Observations of hens’ spatial distribution were conducted immediately before and after, and 3 wk after hens gained access to litter. More HB and BB hens were in upper tiers in morning compared to DW and W36 (all P ≤ 0.05). However, DW and W36 hens roosted in upper tiers in larger numbers than HB and BB during evening (all P ≤ 0.05). More DW and W36 hens were on litter compared to BB and HB, particularly when litter was first accessible (all P ≤ 0.05). The number of hens on litter increased over time for all strains (P ≤ 0.06). White hens on litter occupied open areas in higher numbers (P ≤ 0.05), while more brown hens occupied litter under the aviary after acclimation (P ≤ 0.05). In the dark period, W36 and DW hens were present in higher numbers in upper tiers than HB and BB, while HB and BB showed higher tier-to-tier movement than DW and W36 (P ≤ 0.05). In general, more white hens roosted higher at night and explored litter sooner, while more brown hens were near or in nests in the morning and moved at night. Distinct strain differences indicate that attention should be paid to the match between configuration of the aviary design and strain of laying hen.

Índice produtivo e qualidade de ovos de galinhas poedeiras submetidas a diferentes métodos de debicagem

Resumo: O objetivo deste trabalho foi avaliar o efeito da debicagem, por meio de lâmina quente ou por radiação infravermelha, sobre os indicadores produtivos e de qualidade de ovos, em três linhagens de galinhas poedeiras na primeira semana de vida, e se uma segunda debicagem seria necessária na décima semana de idade. As aves foram distribuídas em um delineamento inteiramente ao acaso, em arranjo fatorial 2x3x2 (primeira debicagem por meio de radiação infravermelha ou por lâmina quente x linhagens Lohmann LSL, Hy-line W-36 e Lohmann Brown x com ou sem debicagem à décima semana de idade), no total de doze tratamentos, com seis repetições. A debicagem por radiação infravermelha, na primeira semana de vida, proporciona os mesmos resultados produtivos e de qualidade dos ovos que o método convencional por lâmina quente. Não houve mortes por canibalismo em aves das três linhagens que não foram submetidas à segunda debicagem, mas se observou decréscimo de 8% da viabilidade, em aves à 63.a semana de idade.

Comparison of liver and bone health of two laying hen strains kept in different cage systems

Summary Concerns have been increasing about conventional cages for laying hens in connection with welfare. Liver and bone disorders of laying hens are major problems. Therefore, the aim of this experiment was to investigate the differences in liver and bone traits of two laying strains kept in conventional and enriched cages. A total of 532 two Lohmann Brown Classic (LB) and 532 Lohmann LSL Classic (LW) hens were housed from 16 to 73 weeks in either conventional cages or enriched cages. Enriched cages had a nesting area, scratch pad, perch and claw shortener. At 73 weeks of age, blood parameters (alanine amino transferase (ALT), aspartate amino transferase (AST), alkaline phosphatase (ALP), calcium (Ca), phosphor (P), cholesterol and triglycerides), relative liver weight, fatty liver score and bone parameters (weight, length, diameter, maximum load, deformation at maximum load and stiffness of tibia and femur) were determined. The cage type affected only serum ALT, AST, ALP and cholesterol levels. Differences of liver and bone parameters between both cage types were not statistically significant. Serum ALT, ALP and P level and also weight and diameter of examined bones were affected by strain. This study indicates that cage type and cage type × strain interactions have limited effect on the liver and bone health.

Administration of extract Salix tetrasperma combined with extract of turmeric and neem to improve eggs quality of chicken reared under heat stress

Quality of eggs might decrease when hens under heat stress. A further study found that a specific plant extracts could reduce the impacts of heat stress. The aim of this study was to determine effects of Salix tetrasperma plant extract in combination with extract of turmeric and neem to improve egg quality and productivity of laying hens under heat stress. Sixty laying hens strain Isa Brown of 6 months old were used and reared in individual cages. The feed and drinking water were supplied ad libitum. This study was conducted in a completely randomized design with five treatments (two controls and three treatments) and each treatment consisted of 12 replication. Treatment consisted of with (KP) and without (KP) commercial anti-stress supplement. Formulations of extract were S. tetrasperma 1.000 mg / l water (EJ), S. tetrasperma 1.000 mg / l + Turmeric 250 mg / l + neem 250 mg / l (EJ+K1), and S. tetrasperma 1.000 mg / l + Turmeric 500 mg / l + neem 500 mg / l drinking water (EJ+K2). The hens were exposed to heat stress for 5 hours per day at a temperature range of 34.0±1.0°C. Supplements were dissolved in drinking water and were given for 30 days in the morning and noon. Results showed that a single extract of S. tetrasperma or the combination of an extract of turmeric and neem were significantly increased thickness of eggshell (P<0.05), but did not affect color of egg yolk, height albumin, egg weight, and HU value. Extract of S. tetrasperma combined with turmeric and neem extract dissolved in drinking water for 30 days in laying hens reared under heat stress could not improved quality of the eggs, but may increase thickness of the egg shell and cause decreased water consumption.

Qualidade interna de ovos submetidos a diferentes tipos de revestimento e armazenados por 35 dias a 25ºC

This study aimed to evaluate the internal quality of eggs subjected to three different types of coatings: no coating (control); 3% gelatin and mineral oil. We used 180 white eggs, with an average weight of 62 g, from laying hens strain Shaver White. Those eggs were stored at a temperature of 25 ° C in a BOD during 35 days and were analyzed every seven days. We evaluated yolk, albumen, shell and weight loss percentage, Haugh units, specific gravity, yolk index, albumen and yolk pH and egg shell color. The results showed that storage time affects the quality of the eggs and the treatment coating the egg with mineral oil were provided the better internal quality of eggs, while the gelatin coating showed intermediate quality and without coating treatment, a poorer quality internal eggs, thus showing necessary to use some kind of coating to increase the shelf life of eggs.

Housing system and laying hen strain impacts on egg microbiology

Alternative hen housing is becoming more commonplace in the egg market. However, a complete understanding of the implications for alternative housing systems on egg safety has not been achieved. The current study examines the impact of housing Hy-Line Brown, Hy-Line Silver Brown, and Barred Plymouth Rock hens in conventional cage, cage-free, and free range egg production systems on shell microbiology. Eggs were collected at 4 sampling periods. Egg shell emulsion pools were formed and enumerated for total aerobic organisms, Enterobacteriaceae, and yeast and mold counts. Hy-Line Brown and Hy-Line Silver Brown hens produced eggs with significantly (P < 0.05 and 0.001, respectively) different levels of aerobic organisms dependent on housing system. Eggs from conventional cages had significantly different (P < 0.05) levels of aerobic contamination in relation to hen strain with Hy-Line Silver Brown having the greatest (4.57 log cfu/mL). Hy-Line Brown and Barred Plymouth Rock hens produced eggs with significantly different (P < 0.01) levels of Enterobacteriaceae among housing systems with conventional caged eggs having the lowest level of contamination for the hen strains. There were no differences within each strain among housing systems for yeast and mold contamination. The study shows that hen strain has an effect on egg microbial levels for various housing systems, and egg safety should be considered when making hen strain selections for each housing system.

Comparative Study on Production Efficiency of Two Strains of Brown and White Egg Laying Hens in Kuwait

2 Abstract: The high nutritional value of eggs makes them an important part of the normal diet of people in general and specifically in Kuwait. The majority of egg consumption in Kuwait and the Gulf area is of the white egg type. However, it is known that the majority consumption in European countries and in the Middle East is of the brown egg type. This could be due to high quality of brown eggs including shell thickness. Therefore, the current research was conducted to assess the quality of brown eggs as compared to white eggs for two laying hen strains under local conditions. Furthermore, comparison between production efficiency of brown and white laying hens was conducted. Hy-line brown and white laying hen strains were used in the current study. During the laying period (22-69 weeks of age), percent egg production, egg weight, egg mass, feed consumption and feed efficiency were determined every four weeks. Shell weight, thickness, yolk and albumen weight and percentage and Haugh unit were determined at different laying periods for both brown and white eggs. It was found that egg production, egg weight and egg mass of the brown hens were significantly (P 0.05) in the feed consumption between brown and white hens. However, feed efficiency was significantly (P<0.05) better for brown hens than that of the white hens. In addition, weight and percentage of egg yolk were somewhat lower in the brown eggs than that in the white eggs. It was also found that shell weight and percentage of shell were better in brown eggs than that in white eggs. Our results indicate that brown hen strains could have better production efficiency and higher egg quality than white hen strains. Therefore, it can be concluded that using brown laying hens could benefit both the poultry industry and consumers in Kuwait.

Viscosity of egg white from hens of different strains fed with commercial and natural additives

Yolk color and egg white (albumen) cleanliness and viscosity are important parameters by which consumers judge the quality of eggs. This study aimed to investigate changes in albumen viscosity during storage of eggs for up to 36 days from two different commercial laying hen strains (Carijo Barbada and Isa Brown) fed a diet containing annatto (1.5 and 2.0%) or a synthetic additive without synthetic colorants (control). Analyses of humidity, albumen height, pH, viscosity, foam formation, and stability were carried out on eggs. Carijo Barbada strain had smaller albumen, lower humidity and higher egg white viscosity than Isa Brown strain; however, with storage, viscosity lowered significantly on both strains. Initially, the addition of 2.0% of annatto or a synthetic additive increased viscosity in both strains, but with storage only the control maintained longer viscosity. Lower viscosity did not change foam density and stability.

Characterization of folate-dependent enzymes and indices of folate status in laying hens supplemented with folic acid or 5-methyltetrahydrofolate

The conversion of folic acid (FA) to the biologically active 5-methyltetrahydrofolate (5-MTHF) is necessary for the deposition of folate in the egg. A study was conducted to compare egg folate concentrations, indices of folate status, and activities of folate-dependent enzymes in response to equimolar intake of either FA or 5-MTHF in laying hens. Forty-eight laying hens, 24 wk of age, from 2 different strains (Shaver White and Shaver Brown) were randomly assigned to receive 1 of 3 (n = 8 per strain) dietary treatments: 1) basal diet with no supplemental folate, 2) basal diet + 10 mg/kg of FA, or 3) basal diet + 11.3 mg/kg of 5-MTHF for 3 wk. A completely randomized design with 3 dietary treatments and 2 laying hen strains in a 3 x 2 factorial arrangement was used. Data were subjected to ANOVA, using the PROC GLM procedure of SAS. Plasma homocysteine, serum, and egg folate concentrations; hepatic serine hydroxymethyltransferase; and methionine synthase activity were affected by dietary folate supplementation but not by its form (FA and 5-MTHF). Relative to control hens, plasma homocysteine was decreased (P < 0.05) by 14.2%, whereas serum and egg folate were increased (P < 0.05) by 78.3 and 61.8%, respectively, in hens consuming either folate compound. Hepatic serine hydroxymethyltransferase and methionine synthase activity were increased and decreased (P < 0.05), respectively, in folate-fed birds compared with control-fed birds. Hepatic dihydrofolate reductase was influenced by both the addition and form of dietary folate, being higher (P < 0.05) in FA-fed birds than in 5-MTHF and control-fed birds. Feed efficiency was improved (P < 0.05) in 5-MTHF-fed birds relative to FA-fed birds. Strain of hen influenced serum folate and plasma homocysteine concentrations but not other indices of folate metabolism. Overall, FA and 5-MTHF have equivalent effects in enhancing egg folate concentrations and improving folate status in laying hens. Also, supplementation and form of folate may modulate the activity of folate-dependent enzymes.

Use of Saccharomyces cerevisiae Cell Walls in Diets for Two Genetic Strains of Laying Hens Reared in Floor and Cages

Two trials were carried out to evaluate the productive response in Bovans white hens housed in cages and Isa Brown hens reared in floor fed with sorghum + soybean meal supplemented with Saccharomyces cerevisiae Cell Walls (CW) growth promoters or zinc bacitracin in the diets. In the first one, 216 Bovans hens, 45 weeks old, reared in pens, were allocated in a completely randomized design in three treatments with 6 replicates of 12 hens each one. In the second one, 600 Isa Brown hens, 43 weeks old, were used and allocated in floor with straw litter and three treatments with 4 replicates of 50 hens each one. For both trials, the following treatments were used: 1.Diet without growth promoter, 2.-As 1 + Zinc bacitracin (30 ppm), 3.As 1 + CW (500 ppm). Water and feed were given ad libitum. Feed intake records, egg production, egg weight, egg mass per bird per day, dirty egg and feed conversion ratio, were taken during 14 weeks. At the end of the trials, to the variables above mentionate, an analysis of time repeated observations was carried out. Results indicated for Trial 1, difference among treatments (p<0.05), with higher percentage of dirty eggs the treatment without promoter. In Trial 2, there was better egg production, feed conversion ratio, egg mass and less dirty eggs with CW, being these results similar to those of Zinc bacitracin treatment (p<0.05) and higher than treatment without promoter. The results obtained show a promoter effect on the production of hens reared in floor, when CW or zinc bacitracin were included in the diet.

Exigência nutricional de metionina+cistina digestíveis para galinhas poedeiras de 54 a 70 semanas de idade

Objetivou-se determinar a exigência de metionina+cistina digestíveis no período de 54 a 70 semanas de idade. Utilizaram-se 360 aves (180 Lohmann LSL e 180 Lohmann Brown) em esquema fatorial 5 × 2 (5 níveis de metionina+cistina digestíveis e 2 variedades) no delineamento inteiramente casualizado com 6 repetições e 6 aves por unidade experimental. Os tratamentos consistiram de dietas suplementadas com cinco níveis de DL-metionina (98%), de forma a proporcionar 0,492; 0,544; 0,596; 0,648 e 0,700% de metionina+cistina digestíveis. Os parâmetros avaliados foram: produção de ovos, peso dos ovos, massa de ovos, consumo de ração, consumo de metionina+cistina digestível, conversão alimentar, componentes dos ovos (albúmen, gema e casca), qualidade interna do ovo (unidades Haugh, índice de albúmen e de gema), percentual de ovos não-comerciais e variação de peso corporal. Os níveis de metionina+cistina digestíveis estudados influenciaram a produção de ovos, o peso dos ovos, a massa de ovos, o consumo de ração, o consumo de metionina+cistina digestíveis, a conversão alimentar, o peso da gema e da casca e a variação de peso corporal. As exigências de metionina+cistina digestíveis foram estimadas pelos modelos de regressão polinomial. O valor estimado para a exigência de poedeiras leves foi de 0,645% de metionina+cistina digestíveis, correspondente a um consumo de 712 mg/ave.dia de metionina+cistina e 12,5 g de metionina+cistina digestível/g de massa de ovo produzida. Para as poedeiras semipesadas, a exigência foi de 0,655% de metionina+cistina digestíveis na dieta, correspondente a um consumo de 723 mg/ave.dia de metionina+cistina e 13,2 g de metionina+cistina digestível/g de massa de ovo produzida.

Exigência nutricional de lisina digestível para galinhas poedeiras no período de 34 a 50 semanas de idade

Com o objetivo de estabelecer a exigência nutricional em lisina para galinhas poedeiras leves e semipesadas, no período de 34 a 50 semanas de idade, 360 poedeiras (metade Lohmann e metade poedeiras Lohmann Brown) foram submetidas à ração basal contendo 2.850 kcal EM/kg, 15,0% PB, suplementada com cinco níveis (0,00; 0,05; 0,10; 0,15 e 0,20%) de L-lisina, de modo a proporcionar 0,584; 0,634; 0,684; 0,734 e 0,784% de lisina digestível nas rações. Foi utilizado esquema fatorial 5 x 2 (nível de lisina e linhagem de aves), com seis repetições por tratamento e seis aves por unidade experimental, em um delineamento inteiramente casualizado. Foram avaliados a produção de ovos (%), a massa e o peso médio dos ovos (g), o consumo de ração (g/ave.dia), a conversão alimentar (kg ração/dúzia ovos), a mudança de peso corporal (g) e a qualidade interna dos ovos (unidade Haugh e índice de albúmen e gema). Os níveis de lisina não influenciaram a mudança de peso corporal, o consumo de ração e a qualidade interna dos ovos em ambas as linhagens. A conversão alimentar e a produção de ovos, o peso médio e a massa dos ovos foram influenciados positivamente pelos níveis de lisina, em poedeiras leves e semipesadas. A exigência em lisina digestível, estimada pelo modelo quadrático, para as aves leves e semipesadas, foi de 0,732 e 0,715% na ração, que corresponde ao consumo diário por ave de 893 e 804 mg lisina/ave.dia, respectivamente.

Exigência nutricional de treonina digestível para galinhas poedeiras no período de 34 a 50 semanas de idade

Com o objetivo de estabelecer a exigência nutricional de treonina digestível para poedeiras leves e semipesadas no período de 34 a 50 semanas de idade, 580 poedeiras (metade Lohmann e metade Lohmann Brown) foram submetidas a uma ração basal contendo 2.850 kcal EM/kg, 14.0% PB, suplementada com cinco níveis (0,00; 0,035; 0,07; 0,105 e 0,140%) de L-treonina, de modo a proporcionar 0,410; 0,445; 0,480; 0,515 e 0,550% de treonina digestível nas rações. Foi utilizado esquema fatorial 5 x 2 (nível de treonina e linhagem de aves), com seis repetições por tratamento e seis aves por unidade experimental, em um delineamento inteiramente casualizado. Foram avaliados a produção de ovos (%), a massa e o peso médio dos ovos (g), o consumo de ração (g/ave.dia), a conversão alimentar (kg ração/dúzia ovos), a mudança de peso corporal (g) e a qualidade interna dos ovos (unidade Haugh e índices de albúmen e gema). Os níveis de treonina não influenciaram a mudança de peso corporal, o consumo de ração, o peso dos ovos e a qualidade interna dos ovos em ambas as linhagens. A conversão alimentar, a produção de ovos, a massa de ovos e a unidade Haugh foram afetadas positivamente pelos níveis de treonina. A exigência de treonina digestível, estimada pelo modelo quadrático, para as poedeiras leves e semipesadas, foi de 0,510 e 0,517% na ração, que corresponde ao consumo diário por ave de 583 e 575 mg treonina/dia, respectivamente.

Exigência nutricional de metionina + cistina digestível para galinhas poedeiras no período de 34 a 50 semanas de idade

Com o objetivo de estabelecer a exigência nutricional em metionina + cistina para galinhas poedeiras leves e semipesadas no período de 34 a 50 semanas de idade, 360 poedeiras (metade Lohmann e metade Lohmann Brown) foram submetidas a uma ração basal contendo 2850 kcal EM/kg, 15,0% PB, suplementada com cinco níveis (0,00; 0,052; 0,107; 0,162 e 0,217%) de DL-metionina + cistina, de modo a proporcionar 0,517; 0,569; 0,624; 0,679 e 0,734% de metionina+cistina digestível nas rações. Foi utilizado esquema fatorial 5 x 2 (nível de metionina + cistina e linhagem de aves), com seis repetições por tratamento e seis aves por unidade experimental, em um delineamento inteiramente casualizado. Foram avaliados a produção de ovos (%), a massa e o peso médio dos ovos (g), o consumo de ração (g/ave/dia), a conversão alimentar (kg ração/dúzia ovos), a mudança de peso corporal (g) e a qualidade interna dos ovos (unidade Haugh e índices de albúmen e gema). Os níveis de metionina+cistina não influenciaram a mudança de peso corporal, o consumo de ração e a qualidade interna dos ovos em ambas as linhagens. A conversão alimentar e a produção de ovos foram influenciados positivamente pelos níveis de metionina+cistina, bem como o peso médio e a massa dos ovos, que apresentaram efeito quadrático, à exceção do peso médio dos ovos das poedeiras semipesadas, que apresentou efeito linear. A exigência em metionina + cistina digestível, estimada pelo modelo quadrático, para as aves leves e semipesadas, foi de 0,693 e 0,692% na ração, que corresponde ao consumo diário por ave de 825 e 793 mg metionina + cistina/dia, respectivamente.

Tracking the development of serum biochemical parameters in two laying hen strains – a comparative study

Abstract. A follow-up, comparative study was designed for the description of differences between two divergent laying hen strains, a Leghorn type and a medium heavy body (MHB) genotype (Hy-Line Brown), in chemical body composition and serum biochemical parameters determined at 3, 4, 6, 8, 10, 12, 14, 18, 20, 25, 30, 52 and 72 weeks of age; each time 5 birds of both genotypes were analysed and exterminated for body composition analysis. Resulting from the genotype-associated differences, the bodyweight of the populations differed from week 20 on. In the chemical body composition dry matter content was similar, while crude protein was higher on weeks 3, 8, 10, and after 18 weeks in the Leghorns. Crude fat content was higher in the brown birds (weeks 8, 10, 25, 30). Total serum protein and albumin showed slightly increasing trends, while serum creatinine concentration showed a downward trend in both genotypes, the MHB birds having higher values. Triglyceride concentration showed a drastic step-up at 17 weeks by changing to the pre-layer diet, coupled with marked between-genotype differences. This quick increase was matched by concentration drops in total and HDL cholesterol, the serum HDL cholesterol of Leghorns being always lower. Sodium concentration showed an increasing tendency with body DM content (R2=0.914, P&lt;0.001, n=115). The Leghorns tended to show minimally higher Ca concentrations. The γ-GT activity was always higher in MHB birds, indicating a less effective hepatic adaptation to the peak production. Applying discriminant analysis to classify the genotypes, 94.4% of the original grouped cases was correctly classified, using all variables.

The effects of short term enrichment on learning in chickens from a laying strain (Gallus gallus domesticus)

Rearing and housing systems can have substantial effects on behaviour and physiology in domestic animals. In laying hens, several housing systems with different degrees of enrichment are in commercial use. Here, we tested effects of short term enrichment of housing conditions on the exploration and learning performance in 6 weeks old chickens of a laying hen strain. Subjects were either kept in a litter floor system indoors or in an identical compartment but with additional access to an outdoor free range 1 week prior to the experiments. Subjects from both treatment groups then were tested for exploration and learning performance in a Y-maze. The short term enrichment resulted in a significant difference in learning behaviour and exploratory behaviour. Subjects from enriched conditions with free range access left the start-box faster (p=0.030), were better in learning the Y-maze task (p=0.033), and made fewer initial mistakes (p=0.012) in the Y-maze than subjects from litter floor without free range access. Thus, subjects from the enriched group explored the Y-maze faster, and had a better and faster learning performance. However, in a memory test conducted after the training phases we did not find any differences between groups. The results show that short term enrichment of housing conditions in chickens can have positive immediate effects on behaviour by reducing behaviours that are likely to reflect fearfulness and by positively affecting learning performance.