1.?A study was conducted to study direct dominance genetic and maternal effects on genetic evaluation of production traits in dual-purpose chickens. The data set consisted of records of body weight and egg production of 49 749 Mazandaran fowls from 19 consecutive generations. Based on combinations of different random effects, including direct additive and dominance genetic and maternal additive genetic and environmental effects, 8 different models were compared.
2.?Inclusion of a maternal genetic effect in the models noticeably improved goodness of fit for all traits. Direct dominance genetic effect did not have noticeable effects on goodness of fit but simultaneous inclusion of both direct dominance and maternal additive genetic effects improved fitting criteria and accuracies of genetic parameter estimates for hatching body weight and egg production traits.
3.?Estimates of heritability (h2) for body weights at hatch, 8 weeks and 12 weeks of age (BW0, BW8 and BW12, respectively), age at sexual maturity (ASM), average egg weights at 28–32 weeks of laying period (AEW), egg number (EN) and egg production intensity (EI) were 0.08, 0.21, 0.22, 0.22, 0.21, 0.09 and 0.10, respectively. For BW0, BW8, BW12, ASM, AEW, EN and EI, proportion of dominance genetic to total phenotypic variance (d2) were 0.06, 0.08, 0.01, 0.06, 0.06, 0.08 and 0.07 and maternal heritability estimates (m2) were 0.05, 0.04, 0.03, 0.13, 0.21, 0.07 and 0.03, respectively. Negligible coefficients of maternal environmental effect (c2) from 0.01 to 0.08 were estimated for all traits, other than BW0, which had an estimate of 0.30.
4.?Breeding values (BVs) estimated for body weights at early ages (BW0 and BW8) were considerably affected by components of the models, but almost similar BVs were estimated by different models for higher age body weight (BW12) and egg production traits (ASM, AEW, EN and EI). Generally, it could be concluded that inclusion of maternal effects (both genetic and environmental) and, to a lesser extent, direct dominance genetic effect would improve the accuracy of genetic evaluation for early age body weights in dual-purpose chickens.
The financial returns expected from improvements in the four important traits were:
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Per bird
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+ 12 in survivors egg production 2S. 4¼d. ± 1¼d.
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—5 in percentage laying mortality is. 5d.± 1d.
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+ 1 g. in average egg weight 10½d. + 1 ½d.
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—5 g. in food consumed per day 43/4d.± 1¼d.
Laying house mortality was found to be positively correlated among the entries with survivors’ average egg production and with average egg weight. 相似文献
Two experiments were conducted to study the effect of including toasted (120°C/35 min) guar meal (GM, Cyamopsis tetragonoloba) in the diet on performance and egg shell quality of White Leghorn (WL) layers.
Totals of 2376 and 2816 layer chickens (Babcock, BV 300) were randomly distributed into 27 and 32 replicates with 88 birds each in Experiments 1 and 2, respectively. Three diets in Experiment 1 (0, 50 and 100 g GM) and 4 diets in Experiment 2 (0, 50, 100 and 150 g GM/kg) were prepared having similar concentrations of energy and protein. Each diet was fed ad libitum to 9 and 8 replicates, respectively, in Experiments 1 (from 53 to 68 weeks) and 2 (35 to 46 weeks of age).
Compared to soya bean meal (SBM) GM contained similar concentrations of protein, but was deficient in all essential amino acids except arginine, which was 70% higher than in SBM. Total non-starch polysaccharide (NSP) content in GM (166 g/kg) was lower than that of SBM (179 g/kg). Amongst different NSP fractions, GM contained higher levels of arabans, xylans, mannans and glucans compared to SBM. The galactomannan gum content in GM was 46 g/kg.
Egg production (EP), body weight (BW), food intake (FI), food efficiency (FE) and egg quality (shell weight, shell per cent, shell thickness, Haugh unit score, egg density and egg breaking strength) parameters were not affected by incorporating GM up to 100 g/kg diet in Experiment 1. However, egg weight (EW) and egg mass (EM) were reduced significantly in groups fed on 100 g/kg diet.
In Experiment 2, EP and FE were not affected by incorporating GM up to 100 g/kg, but were reduced at 150 g/kg diet. FI, EW, BW and egg quality parameters were not affected by incorporating toasted GM up to 150 g/kg diet.
Based on the results of both experiments, it is concluded that toasted GM can be included in WL layer diets up to 100 g/kg without affecting EP, FE, EW, EM, Haugh unit score, BW and egg shell quality parameters.
The aims of the present study were to examine whether collagen exists in egg, particularly in egg yolk; to establish a Fourier transform-near infrared (FT-NIR) measurement method for collagen in egg and to assess the possibility of increasing the collagen content by feeding hens a diet containing wood charcoal powder containing wood vinegar liquid (WCV).
The collagen in eggs from 67-week-old hens fed on the dietary 0 and 9.9 g/kg WCV diets was investigated using a combination of histochemical, matrix-assisted laser desorption ionisation with time-of-flight mass spectrometry (MALDI-TOF MS), Fourier transform infrared (FT-IR) and FT-NIR approaches.
All approaches used to identify collagen in egg yolk yielded positive results.
The collagen in egg yolk measured using colorimetry, collagen in egg yolk, egg white and eggshell membrane using FT-NIR and collagen in egg yolk determined by treating the egg yolk with collagenase were abundant after feeding a dietary WCV (p<0.05).
These results suggest that egg yolk contains collagen, that the collagen in egg can be measured using FT-NIR, and that the collagen content of egg yolk can be increased by feeding dietary WCV diets.
A total 120 laying hens (60 TETRA BLANCA white egg layers and 60 TETRA SL brown egg layers) were selected from 250 TETRA BLANCA and 250 TETRA SL pullets based on their predicted body fat content by means of computed tomography (CT) at 16 weeks of age. Three groups of pullets were chosen for the investigation with the highest (n = 20), lowest (n = 20) and average (n = 20) body fat content.
Changes in the live weight, body fat content, egg production and egg composition of the chosen animals were recorded at 32, 52 and 72 weeks of age.
Based on the results, it was established that differences in starting body fat content of the hens remained the same during the experimental period. The differences between the two extreme groups were statistically significant at each age.
The starting body fat content of the hens affected the rate of egg production, i.e. hens with high starting body fat content produced 11–14 eggs fewer than the hens with a low or average body fat content but had no effect on the composition of the eggs.
Genotype affected almost all of the examined traits: TETRA BLANCA hens had lower live weight and higher body fat content during the experimental period and produced fewer eggs with lower albumen and higher yolk, dry matter and crude fat content than the TETRA SL hens.
The estimation of sulphur amino acid requirement is a vital key to providing appropriate nutrition in poultry. The estimation of amino acid requirement depends on what production parameter is taken into consideration for optimisation.
A complete randomised block design was performed with 5 treatments and 6 replicates of 8 Hy-line layers (W-36) each from 32 to 44 weeks of age. The blocks were made to have a replicate of each treatment. The dietary treatments were consisted of 5 concentrations of digestible sulphur amino acid (DSAA) at 5.1, 5.6, 6.1, 6.6 and 7.1 (g/kg).
Egg production, egg mass, egg weight and feed conversion ratio (FCR) were significantly affected by an increase in DSAA intake. However, feed intake, egg component yield, Haugh unit, specific gravity, eggshell thickness, egg protein and dry matter (DM) were not altered by DSAA intake.
A significant increment in plasma high-density lipoprotein was concomitant with a reduction in low-density lipoprotein when DSAA intake was increased. However, triglyceride, cholesterol, uric acid and total protein in plasma were not affected by DSAA intake.
The DSAA requirements estimated by the linear broken-line model to optimise egg production, egg mass, egg weight and FCR were 678, 673, 641 and 656 mg/bird.d in the whole experimental period, respectively.
The DSAA requirement estimated by the quadratic broken-line model to optimise egg production, egg mass, egg weight and FCR were 4.71%, 7.87%, 8.73% and 7.62% higher than those estimated by linear broken-line fit model in the whole experimental period, respectively.
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the force required to shear egg shell material can be measured with high precision by pressing a narrow, flat‐ended plunger on to the shell;
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shearing force falls and the precision of its measurement rises as the radius of the plunger is reduced;
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shearing force is related linearly to shell thickness ;
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the regression line of shearing force on shell thickness does not pass through the origin but has a substantial positive intercept on the thickness axis, at about a third of the mean thickness ;
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there are differences between hens and between strains of hen in the magnitude of the intercept, but not in the slope of the regression;
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shearing force is affected also by the glossiness of the shell;
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shearing force was not significantly affected by stripped membrane thickness, number of mammillae per unit area of shell, shell organic content (standardised for shell thickness), shell curvature, shell colour, mottling score, translucent patch score, speckling score, age of the egg or age of the hen that laid it;
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measured with a plunger of radius 165 μm, the mean shearing strength of incremental shell was 57 kg wt/mm2 (3–7 ton/in2).
The findings suggest that the shearing strength of egg shells might be increased by direct selection and by selection for shell glossiness. 相似文献
The objective was to investigate inbreeding depression for some economic traits of Mazandaran native fowls using data collected from 1992 to 2012 (21 generations) using a REML animal model of significant fixed and random effects with inbreeding of birds and dams as covariates.
The mean inbreeding coefficient (F) for the whole population and dams was 4.67% and 4.12%, respectively, and most of the inbred birds (75.79%) and inbred dams (72.58%) had F < 12.5%.
Individual and dam inbreeding trends were 0.55% and 0.53% per year.
Inbreeding depression for body weight at hatch, at 8 weeks and 12 weeks of age, age at sexual maturity, weight at sexual maturity, egg weight at 1st d of laying and average egg weight at 28, 30 and 32 weeks of laying due to a 1% increase in individual inbreeding were ?0.11 g, ?3.1 g, ?1.3 g, 0.15 d, 0.59 g, ?0.05 g and ?0.03 g, respectively.
A 1% increase in maternal inbreeding resulted in a reduction of 0.06, 0.6 and 3.6 g in body weight at hatch, 8 weeks and 12 weeks of age.
In the past 50 years, selection starting initially at the breed level and then using quantitative genetics coupled with a sophisticated breeding pyramid, has resulted in a very productive hybrid for a variety of traits associated with egg production.
One major trait currently being developed further is persistency of lay and the concept of the “long life” layer. Persistency in lay however cannot be achieved without due consideration of how to sustain egg quality and the health and welfare of the birds in longer laying cycles. These multiple goals require knowledge and consideration of the bird’s physiology, nutritional requirements, which vary depending on age and management system, reproductive status and choice of the selection criteria applied.
The recent advent of molecular genetics offers considerable hope that these multiple elements can be balanced for the good of all in the industry including the hens.
The “long life” layer, which will be capable of producing 500 eggs in a laying cycle of 100 weeks, is therefore on the horizon, bringing with it the benefits of a more efficient utilisation of diminishing resources, including land, water, raw materials for feed as well as a reduction in waste, and an overall reduced carbon footprint.
In this study, 6 dietary DL-methionine (Met) levels (2.5, 3.0, 3.5, 4.0, 4.5 and 5.0?g/kg) were tested to estimate the dietary Met requirements of Longyan ducks from 19 to 46 weeks of age, and to investigate its effect on the glutathione redox system.
In total, 1080 Longyan ducks aged 19 weeks were allocated randomly to the 6 dietary treatments, where each treatment comprised 6 replicate pens with 30 ducks per pen.
Met had no effects on egg production, yolk weight, yolk colour or the glutathione redox system, but the egg weight, egg mass and feed conversion ratio (FCR) were improved significantly by dietary Met supplementation. As the dietary Met concentration increased, the eggshell thickness and breaking strength decreased significantly, whereas the albumen weight increased significantly.
According to broken-line regression analysis, the optimum Met requirements for egg weight, egg mass, FCR and albumen weight are 686, 661, 658 and 731 mg/bird/d, respectively, with a dietary crude protein level of 170 g/kg.
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most cracks that occur in a battery cage are produced when the egg drops on to the floor at oviposition;
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they are located predominantly in the two polar thirds of the shell;
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their incidence is determined mainly by the effective mass of the cage floor, the mean drop height and the mean attitude of the eggs at emergence from the cloaca (broad or narrowpole first) ;it is affected only slightly by the mean shell thickness and the overall mean shell curvature (egg size);
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if a hen is kept on a floor with a high effective mass, an indirect estimate of her mean drop height can be obtained quickly, easily and with high precision from observations made on her eggs after they have been laid; the observations required are the incidence of eggs with poorly formed shells, the type, location and incidence of cracks in eggs with well‐formed shells and the mean weight of the eggs;
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the incidence of cracking on a heavy cage floor can be used to predict the incidence on a normal floor;
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the incidence of cracking is heritable and responds rapidly to downward selection.
It is suggested that breeders should test the technique described, with a view to adopting it as a method of selecting for low crack incidence. 相似文献
An experiment was conducted to determine the effects of dietary supplementation of thymol, synbiotic (Biomin, IMBO) and their combination in laying hen diets on laying performance, egg quality and serum metabolic profile from 24 to 36 weeks of age.
Treatment groups were fed on a control diet, the control diet supplemented with thymol (250 mg/kg), the control diet supplemented with synbiotic (250 mg/kg) or the control diet supplemented with a combination of thymol (250 mg/kg) and synbiotic (250 mg/kg).
Supplementation of thymol and synbiotic, separately as well as combined, improved egg weight, egg production, egg mass and feed conversion ratio from 24 to 36 weeks of age. The eggs obtained from thymol, synbiotic or their combination treatments displayed higher values of shell thickness, Haugh unit and shell percentage compared to the control.
Serum cholesterol significantly decreased in the single or combined form of thymol and synbiotic supplementation treatments.
The serum biochemical profiles, thyroid hormones, body weights and the production and quality of eggs subsequent to moulting, were compared in laying hens subjected to conventional forced moulting or forced moulting with a diet high in zinc.
A total of 200 Dekalb White laying hens in their second production cycle were studied. Blood sampling was conducted in a factorial experimental design (2 × 3) with two methods of moulting (fasting or zinc) and three sampling periods (pre-moult, moult and subsequent peak).
Total egg protein content, including globulins, was greater with the zinc diet, whereas egg weight and albumen percentage were greater after fasting. The zinc method resulted in an increased shell thickness and calcium percentage but lower percentage of phosphorus. During the moulting period, the hens in the zinc group had heavier mean body weights.
It was concluded that moulting with a high-zinc diet could replace fasting, without negative effects on body weight, biochemical variables or subsequent egg quality and production. The zinc method was also better for the birds’ welfare.
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The shift of the yolk during a storage period of 7 d at a temperature of 20 °G
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The height of the thick albumen directly after lay, and at the end of the storage period
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The diameter of the yolk
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The shape index of the egg.
The correlation, on a hen basis, between the shift of the yolk and the other above‐mentioned traits was only of very minor importance. This means that one of the arguments on the basis of which the height of the thick albumen was used as a criterion for the internal quality of eggs—the influence of the thick white on the central position of the yolk—has lost much of its significance.
In addition the same measurements were made on eggs from 12 entries at the Random Sample Testing Station at Putten. Here samples of 20 eggs per entry were taken. Contrary to expectation the combination of a large amount of thick albumen and a large shift of the yolk proved to be the rule rather than the exception. 相似文献
The types and methods of use of antibiotics in poultry farms in Cameroon, residual levels and potential microbial resistance were determined.
A questionnaire-based survey identified the different antibiotics used and high-performance liquid chromatography (HPLC) was used to determine residual levels of antibiotics.
Pathogens were isolated, identified by use of commercial API kits and minimum inhibition concentration (MIC) was determined.
Oxytetracyclin, tylocip and TCN (oxytetracycline, chloramphenicol and neomycin) were the most frequently used antibiotics. Antibiotics screened by HPLC were chloramphenicol, tetracycline and vancomycin. All of them except vancomycin were detected, and the concentration of these antibiotics was higher than the maximum residual limits (MRL) set by regulatory authorities.
No residues of various antibiotics were found in egg albumen or yolk. The concentration of tetracycline was significantly higher in liver (150 ± 30 µg/g) than in other tissues.
Foodborne pathogens, including Salmonella spp., Staphylococcus spp., Listeria spp., Clostridium spp. and Escherichia spp., were identified. Most of the pathogens were resistant to these various antibiotics tested.
These findings imply the need for better management of antibiotic use to control sources of food contamination and reduce health risks associated with the presence of residues and the development of resistant pathogens by further legislation and enforcement of regulations on food hygiene and use of antibiotics.
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the force required to produce tensile failure did not vary linearly with the width of the piece of shell under test, but with its two‐thirds power;
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it varied linearly with the thickness of the shell;
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the line relating force at tensile failure to shell thickness did not pass through the origin but intercepted the thickness axis at between about 90 and 130 μm, indicating that the inner layers of a shell, up to about a third of its thickness, contributed little or nothing to its tensile strength;
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the slope of the line did not vary with hen or strain of hen, indicating that the shells did not differ in the tensile strength of the material constituting their outer layers (i.e. about the outer two‐thirds);
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there were differences between hens and strains in the magnitude of the intercept: shells of the same thickness but from different hens or strains differed in force at tensile failure;
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the existence of between‐strain differences in intercept constitutes prima facie evidence that the variation in this trait is under genetic control;
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there was a fairly large within‐egg residual component of the variance of force at tensile failure; it represents real variation in tensile strength between apparently similar pieces of the same shell and is believed to be an effect of chance in the distribution of flaws in the shell material;
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for any one hen the intercept is the same as that found when shearing strength is measured, so shearing strength (which can be determined easily, quickly and precisely) can be used as a predictor of tensile strength.
Implications for poultry breeders are discussed; it is suggested that they should select for shell strength instead of shell thickness, measuring strength as shearing strength. 相似文献
The objective of the study was to investigate the distribution of LPIN2 variants and haplotypes among breeds and perform an association analysis of the variants and haplotypes with the broiler traits in chickens.
Six breeds were used to study the variation and distribution of chicken LPIN2, and an F2 resource population was used to measure growth traits, carcass traits, meat quality traits and serum biochemistry parameters.
A c.-599G>A variant was located in the promoter region of LPIN2 and c.444G>A and c.1730A>T (E577D) coding variant mutations were detected. Linkage disequilibrium tests showed that these three variants were under moderate linkage disequilibrium in the 6 breeds and 7 haplotypes were constructed. The distribution of variation/haplotypes presented clear differences among breeds.
Association analysis showed that c.-599G>A was associated with leg muscle weight, jejunum length, ileum length, leg muscle fibre density and leg muscle fibre diameter; c.444G>A was associated with spleen weight, ileum length, body weight at hatch and metatarsus length at 8 weeks; c.1730T>A had significant effects on chicken liver weight, heart weight, body weight at 10 weeks, serum albumin and glucose.
Diplotypes were significantly associated with body weight at hatch, heart weight, pancreas weight, duodenum length, leg muscle fibre density and lactate dehydrogenase.
The aim of this study was to evaluate the tolerance of laying hens for an excessive L-valine (L-val) supply on laying performance, egg quality, serum free amino acids, immune function and antioxidant enzyme activities of laying hens.
A total of 720 HyLine Brown hens were allocated to 5 dietary treatment groups, each of which included 6 replicates of 24 hens, from 40 to 47 weeks of age. Graded amounts of L-val were added to the basal diet to achieve concentrations of 0 (control), 1, 2, 3 and 4 g/kg, respectively, in the experimental diets.
Supplementing the diet with L-val did not affect egg production, egg mass, egg weight, feed conversion ratio (FCR) or egg quality. The average daily feed intake response to supplemental L-val was quadratic and was maximised at 2.0 g L-val/kg diet. No differences were observed for total protein, total amino acids, blood urea nitrogen (BUN), uric acid, lactate dehydrogenase (LDH), alkaline phosphatase (AKP), Ca and P concentrations among the treatments.
Serum albumin concentration increased significantly in response to supplemental L-val and was also maximised at 2.0 g/kg. In addition, serum glucose increased quadratically to peak at 2.0 g L-val/kg diet. Serum free valine increased as L-val concentration increased to 2.0 g/kg diet and then decreased linearly.
Supplementation of L-val did not affect the serum concentrations of total antioxidative capability (T-AOC), superoxide dismutase (SOD) and malondialdehyde (MDA). L-val supplementation did not affect the concentrations of immunoglobulins IgG, IgA, IgM and complements (C3 and C4). Serum concentration of triiodothyronine (T3) increased significantly at 2.0 g L-val/kg diet.
It is concluded that high concentrations of L-val are tolerated and can be successfully supplemented into diets without detrimental effects on laying performance or immune function of laying hens.
1. Guinea fowl hens were inseminated weekly once with two doses of spermatozoa (75 million and 100 million) in two different diluents, Beltsville poultry semen extender (BPSE), and Instruments for Veterinary Medicine (IMV), each with and without pre-insemination vaginal douching. Per cent fertility, hatchability, dead germ, dead in shells along with data on sperm egg interaction and vaginal microbial counts were recorded.
2. Artificial insemination had significantly improved the per cent fertility and hatchability compared to natural mating. Dose dependent improvement in fertility was noticed with both diluents.
3. There was a beneficial effect of vaginal douching, which was more pronounced at lower insemination doses.
4. For optimum fertility and hatchability in guinea fowl, insemination of 75 million spermatozoa diluted in BPSE once in 4 d and 100 million spermatozoa diluted in BPSE or IMV once in 5 d coupled with vaginal douching is recommended.
The advantage of supplemental sodium bicarbonate (NaHCO3) on eggshell quality in laying hens changes with age. Besides increasing calcium (Ca) secretion in the eggshell gland, it may improve Ca absorption in the intestine or kidney.
Hy-Line Brown layers (n = 384), 25 weeks of age, were allocated to two treatment groups in two experiments, each of which included 4 replicates of 24 hens. Hens were fed a basal diet (control) or the basal diet containing 3 g NaHCO3 g/kg for 50 or 20 weeks in Experiment 1 or 2, respectively. A 24-h continuous lighting regimen was used to allow hens to consume the dietary supplements during the period of active eggshell formation.
In Experiment 1, particularly from 25 to 50 weeks of age, and in Experiment 2, NaHCO3 supplementation favoured hen-d egg production at the expense of lower egg weight. The increased eggshell thickness should have nothing to do with the additional eggshell formation, because of the unchanged egg mass and daily eggshell calcification.
At 35 weeks of age in both experiments, NaHCO3 supplementation increased duodenal expression of calbindin-d28k (CaBP-D28k) protein, contributing to higher Ca retention and balance.
From 50 to 75 weeks of age in Experiment 1, the hens had little response to NaHCO3 supplementation and showed a negative trend on eggshell thickness and strength.
It is concluded that dietary supplementation with 3 g NaHCO3 g/kg improves Ca absorption and eggshell quality of laying hens during the peak but not late production period, with the introduction of continuous lighting.