Shell Quality Traits Research Articles

Effect of cage space allowance on egg production, egg quality, immune responses and anti-oxidant variables in White Leghorn layers

A comprehensive study was conducted to optimise cage space allowance (CSA) for White Leghorn (WL) layers (65-80 weeks of age). For the purpose, a total of 900 layers were housed in California colony cages in an open sided poultry house at three different CSA (422, 563, 844 cm2/bird). Each of the CSA was studied with 20 replicates. The daily egg production (EP), feed intake (FI), feed efficiency (FE, FI/egg mass) and egg quality traits were recorded at the end of each 28d interval. Anti-oxidant responses like lipid peroxidation (LP) and glutathione peroxidase, glutathione reductase and superoxide dismutase in blood were measured at 80 weeks of age. Similarly, the antibody titres against ND vaccine and cell mediated immune response (CMI) against PHA- P were measured at 80 weeks of age. The variation in CSA did not influence EP, egg mass, weight gain and egg shell thickness. The FI reduced and FE improved with reduction in CSA. However, the egg density and egg shell percentage increased with increase in CSA. The LP was higher and the activities of anti-oxidant enzymes were lower at 422 cm2/bird as compared to the higher space allowances. No effect of CSA on ND titre was observed, while the CMI response was higher at 844 cm2/ bird than the other two CSA. It could be concluded that, though the FE was better at 422 cm2/b, the trends of shell quality traits and antioxidant variables indicated 546 cm2/bird as requirement for WL layers in open sided poultry house under tropical regions.

Influence of Genotype on Productivity and Egg Quality of Three Hen Strains Included in a Biodiversity Program.

The aim of the study was to evaluate the effect of genotype on the productivity and egg quality of three hen strains included in the genetic resource protection program in Poland. The study encompassed populations of laying hens, i.e., Rhode Island Red/RIR (R-11 and K-22) and Rhode Island White (A-33). The analysis over five generations included the basic production traits, i.e., the weight of the birds at 20 weeks (g), egg weights at 33 and 53 weeks, sexual maturity, the number of eggs laid up to 56 weeks of age, and hatchability parameters. In addition, the effective population size (Ne) and flock homozygosity coefficient (Fx) were calculated for each breed. Population health during the rearing and production periods was also recorded. The study also determined egg content and shell quality traits in relation to the age of the hens. The birds were kept on litter at a stocking rate of 5 hens/m2 and fed ad libitum with a standard feed mixture for hens. Based on the results, it was concluded that the evaluated hen populations (R-11, K-22, and A-33) are valuable strains, representing a reservoir of unique phenotypic and egg quality traits. It was shown that the random mating system used in the reproduction of flocks effectively protects the populations from an increase in the degree of inbreeding. An influence of hens' origin (genotype) and age on the performance results, as well as egg quality traits, was found. Over five generations, the evaluated hen strains were characterized by high survival rates (above 98%). The study also found a large variation between the R-11 and K-22 strains and the A-33 strain in terms of the evaluated performance traits, especially in the body and egg weights, sexual maturity age, and laying performance of hens. The earliest to start laying were hens from the K-22 strains, which also showed significantly (p ≤ 0.05) higher laying performances compared to R-11 hens. The results also indicate that the quality of eggs from hens of the compared strains varied. This was particularly true for such traits as shell color; egg, shell, and yolk weight; and shell quality. It was also shown that many egg and shell quality traits change with the age of the hens. The analysis of the obtained data indicates that the adopted methods of conservative breeding for these populations have influenced the success of the conservation program.

Quality of Table Eggs from Different Production Systems

Summary The production system is one of the most significant factors influencing internal and external egg quality. Due to concerns for the welfare of laying hens, and on the basis of Council Directive 1999/74/EC, EU countries banned conventional cages, so it is necessary to determine the influence of alternative systems on the external and internal quality traits of table eggs. Consumers believe that organic eggs are healthier than eggs from the conventional production systems. In addition, consumer awareness of the welfare of laying hens has been raised in the last few decades. This research aimed to determine the quality of table eggs from the cage, free-range and organic systems that are present on the Serbian market. External and internal quality traits were examined for 30 eggs taken from the market from the cage, organic and free-range systems. The value of Haugh units was 77.16 for organic eggs, 66.01 for conventional cages, and 62.01 for free-range system. The results showed that eggs from the organic system had significantly higher egg weight, shape index, albumen height, and Haugh units (p≤0.05) compared to cage and free-range eggs. Eggs from the free-range system had the highest number of meat and blood spots (2.25), while it was the lowest in eggs from the cage system (0.40). Eggs from organic production and conventional cages showed better results in internal and external egg quality. Shell quality traits, yolk color, and yolk pH were not affected by the production system.

Accuracy of genomic prediction of shell quality in a White Leghorn line

Several genomic methods were applied for predicting shell quality traits recorded at 4 different hen ages in a White Leghorn line. The accuracies of genomic prediction of single-step GBLUP and single-trait Bayes B were compared with predictions of breeding values based on pedigree-BLUP under single-trait or multitrait models. Breaking strength (BS) and dynamic stiffness (Kdyn) measurements were collected on 18,524 birds from 3 consecutive generations, of which 4,164 animals also had genotypes from an Affymetrix 50K panel containing 49,591 SNPs after quality control edits. All traits had low to moderate heritability, ranging from 0.17 for BS to 0.34 for Kdyn. The highest accuracies of prediction were obtained for the multitrait single-step model. The use of marker information resulted in higher prediction accuracies than pedigree-based models for almost all traits. A genome-wide association study based on a Bayes B model was conducted to detect regions explaining the largest proportion of genetic variance. Across all 8 shell quality traits analyzed, 7 regions each explaining over 2% of genetic variance and 54 regions each explaining over 1% of genetic variance were identified. The windows explaining a large proportion of genetic variance overlapped with several potential candidate genes with biological functions linked to shell formation. A multitrait repeatability model using a single-step method is recommended for genomic evaluation of shell quality in layer chickens.

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

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

Effect of different split-feeding treatments on performance, egg quality, and bone quality of individually housed aged laying hens.

In order to try to combat the effect of age on eggshell quality in aged laying hens, 5 split-feeding treatments were compared with conventional feeding between 75 and 92 wk of age. In the conventional treatment (T1), the same morning (M) and afternoon (A) diet was fed containing fine (FL) and coarse (CL) limestone at a 50:50 ratio. In the split treatments, the ratio of FL and CL was 50:50 or 30:70, and time of administration (M/A) differed. The following treatments were given: T2 = 50FL-M:50CL-A, T3 = 50CL-M:50FL-A, T4 = 30FL-M:20FL-A+50CL-A, T5 = 30FL-M:70CL-A, and T6 = 0M:30FL-A+70CL-A. A total of 12 individually housed Dekalb white hens was used per treatment. Feed intake, nutrient intake, and laying % was lower in T1 compared to all split treatments (P≤0.001). Due to this low performance in T1, split feeding could not be compared to the conventional system in this trial. By the end of the trial, eggshell quality was improved in T1 as a result of low laying % and more frequent and longer laying pauses. In the split treatments, laying % and feed intake were similar, except in T3 in which a decrease was observed after 81 wk (P≤0.05). Egg weight was higher in T5 and T6 due to higher total and morning protein intake compared to T3 (P≤0.05). Feeding only 50FL-A in T3 not only resulted in lower performance but also in consistently lower shell thickness, indicating a negative effect of suboptimal limestone supplementation. In the split-feeding system, the most optimal combination of morning and afternoon diet was a morning diet with only FL and an afternoon diet with only CL (T2), which both provided ∼50% of the total daily Ca intake. Shell breaking strength and dynamic stiffness could be maintained on this diet between 75 and 92 weeks. Decreasing the amount of Ca in the morning and increasing it in the afternoon did not improve shell quality traits. Bone quality was not affected by limestone particle size or inclusion level in the split-feeding system.

Genetic parameters of body weight, egg production, and shell quality traits in the Shan Ma laying duck (Anas platyrhynchos)

Three hundred and four female ducks of the Chinese indigenous Shan Ma breed, progeny of 11 sires and 104 dams, were used to study laying traits. Among them, 264 ducks were used to study the egg shell quality traits of eggs laid at 300days of age. The mean age at first egg was 109days with an average egg weight of 49.6±3.7g. Between 210 and 300days of age, egg weight increased from 65.0±3.9g to 67.0±4.2g and the mean of the number of eggs laid up to 300days was 161±15.0. Egg length was 59.57±3.01mm and egg width was 45.02±1.98mm, leading to a shape index of 1.32±0.08. Egg shell thickness was about 0.31mm whatever the shell region, and the breaking strength was 28.80±8.29N. The heritability's estimated using restricted maximum likelihood ( REML: ) methodology were high for egg weights (ranging from 0.43 to 0.61), intermediate for the number of eggs laid (ranging from 0.38 to 0.43), and low for the age at first egg (0.13). Heritability's for egg shell quality traits varied from 0.20 for the breaking strength to 0.44 for egg length, with in-between values of 0.28 for shell thickness and 0.34 for the shape index. The number of eggs laid was not genetically correlated with the age at first egg or egg weight, but was correlated with body weight (rg = +0.54±0.23). High positive correlations were found between egg weight and body weight traits, and both of these traits (except egg weight at first egg) were highly and positively correlated with egg length and width. Breaking strength was genetically correlated with egg shell thickness (rg = +0.54±0.19) and the shape index (rg = +0.71±0.23). These results suggest that an efficient selection strategy could be implemented to improve the egg production of the pure Shan Ma duck line.

Changes in egg quality traits during the last phase of production: is there potential for an extended laying cycle?

1. A field study was conducted to investigate the deterioration of eggshell quality at the end of lay and examine the potential to extend the production cycle. A total of 1200 eggs were assessed originating from commercial farms in Belgium: eggs were random sampled at the collection belt at 57–65 weeks of age and at the end of the production cycle (74–92 weeks).2. Based on a linear mixed model, egg quality was estimated for an average flock at 60 weeks of age and changes in quality traits were predicted until the end of the laying cycle.3. Egg weight increased by 0.07 g every week from 60 weeks of age onwards and shape index decreased by 0.04 unit weekly (P < 0.001). Haugh unit values decreased weekly by 0.38 units whereas relative yolk weight was unaffected after 60 weeks of age. Relative albumen weight showed a weekly increase of 0.02% and relative shell decreased by 0.02% weekly until the end of lay.4. Shell quality traits were also influenced by age: shell index decreased by 0.013 g weekly, shell thickness was calculated to be 0.23 µm thinner every week, deformation increased by 0.06 µm weekly from 60 weeks to the end of the laying cycle. Variability of the deformation of eggs indicated more heterogeneous shell quality at the end of the production cycle. Dynamic stiffness increased from 60 weeks of age on.5. Laying hens were depopulated on average at 80 weeks of age (varying from 74–92 weeks). Although ageing had a significant effect on most of the egg quality traits, egg quality was still acceptable at the end of lay, indicating the potential to extend the laying cycle.

Egg shell quality in Japanese quail: characteristics, heritabilities and genetic and phenotypic relationships

The objective of the present study was to estimate heritabilities as well as genetic and phenotypic correlations for egg weight, specific gravity, shape index, shell ratio, egg shell strength, egg length, egg width and shell weight in Japanese quail eggs. External egg quality traits were measured on 5864 eggs of 934 female quails from a dam line selected for two generations. Within the Bayesian framework, using Gibbs Sampling algorithm, a multivariate animal model was applied to estimate heritabilities and genetic correlations for external egg quality traits. The heritability estimates for external egg quality traits were moderate to high and ranged from 0.29 to 0.81. The heritability estimates for egg and shell weight of 0.81 and 0.76 were fairly high. The genetic and phenotypic correlations between egg shell strength with specific gravity, shell ratio and shell weight ranging from 0.55 to 0.79 were relatively high. It can be concluded that it is possible to determine egg shell quality using the egg specific gravity values utilizing its high heritability and fairly high positive correlation with most of the egg shell quality traits. As a result, egg specific gravity may be the choice of selection criterion rather than other external egg traits for genetic improvement of egg shell quality in Japanese quails.

Assessing the thermo-tolerance potentials of five commercial layer chicken genotypes under long-term heat stress environment as measured by their performance traits

This study was conducted to test the thermo-tolerance ability of five commercial chicken genotypes (Lohmann Brown, LB; Lohmann White, LW; New Hampshire, NH; White Leghorn selected for low feed expenditure, WL-FE and White Leghorn with sex-linked dwarf gene, WL-dw) under long-term heat exposure. Two-hundred forty female chickens were assigned to a completely randomized design in a 5 × 2 factorial arrangements (five genetic groups and two ambient temperatures [thermo-neutral, 18–20 °C; heat stress, 30–32 °C]). Individual eggs were collected on daily basis while egg weight and feed intake were determined on individual and group basis at 28-days intervals, respectively. Shell quality traits were determined at 25, 40 and 56 weeks age. No Genotype × ambient temperature interactions were found except for body weight and egg deformation. Chickens at thermo-neutral temperature produced significantly heavier eggs than those of heat-exposed (60 g vs. 54 g). Hen-housed egg production of chickens in thermo-neutral temperature was significantly higher than those of heat-stressed (76.8 % vs. 66.2 %). Daily egg mass production at thermo-neutral and heat stressed chickens was 46 g and 35.8 g, respectively. Feed consumption in heat-stressed and thermo-neutral chickens was 109 and 80.8 g, respectively. Shell thickness, breaking strength and Haugh unit values were significantly reduced in heat-stressed chickens. Among heat-exposed chickens, the NH had the highest body weight while the LW produced 10 % more eggs than the group average. The heat-induced effect on shell quality traits was lowest in LW chickens. The results indicated that the magnitude of heat stress was breed dependent in which the LB showed poor adaptability to heat stress while both NH and LW genotypes demonstrated better thermo-tolerance ability.

Genetic analysis of egg quality traits in White Leghorn chicken

Aim: The present study was undertaken to estimate the genetic parameters and to assess the inheritance pattern of egg quality traits in White Leghorns. Materials and Methods: Data on 480 eggs produced by 40 week old pullets of 4 genetic groups were used for studying egg quality traits. Heritabilities and correlations were estimated by full sib correlation method using Mixed Model Least Squares and Maximum Likelihood (LSMLMW) computer program. Results: The egg weight, haugh unit, yolk index, albumen index, yolk weight, albumen weight, shell weight and shell thickness ranged from 50.01 ± 0.48 to 53.89 ± 0.43 g, 65.38 ± 0.92 to 80.98 ± 1.01, 0.341 ± 0.003 to 0.353 ± 0.003, 0.056 ± 0.002 to 0.087 ± 0.002, 14.16 ± 0.13 to 15.58 ± 0.12 g, 30.92 ± 0.39 to 33.18 ± 0.39 g, 4.32 ± 0.05 to 5.12 ± 0.05 g and 0.336 ± 0.003 to 0.376 ± 0.003 mm, respectively. Heritability estimates for egg weight, yolk index, albumen index and albumen weight ranged from low to medium while those of haugh unit, yolk weight, shell weight and shell thickness ranged from low to high. The genetic and phenotypic correlations of egg weight with other egg quality traits except shell quality traits were mostly positive and moderate to high. High positive genetic and phenotypic correlations between haugh unit and other traits were observed. Genetic correlation of yolk weight with albumen weight was positive while that with shell quality traits was mostly negative. Shell weight was positively correlated with shell thickness. Conclusion: Significant genetic group differences were observed for various egg quality traits studied. The heritability estimates for different egg quality traits were low to moderate. The association among egg quality traits was positive in general.

Assessing the Thermo-Tolerance Potentials of Five Commercial Layer Chicken Genotypes Under Long-Term Heat Stress Environment as Measured by Their Performance Traits

This study was conducted to test the thermo-tolerance ability of five commercial chicken genotypes (Lohmann Brown, LB; Lohmann White, LW; New Hampshire, NH; White Leghorn selected for improved feed efficiency, WL-FE and dwarf White Leghorn, WL-dw) under long-term heat exposure. Two-hundred forty female chickens were assigned to a completely randomized design in a 5 × 2 factorial arrangement (five genetic groups and two ambient temperatures [thermo-neutral, 18-20 C; heat stress, 30-32 C]). Individual eggs were collected on daily basis while egg weight and feed intake were determined on individual and group basis at 28days intervals, respectively. Shell quality traits were determined at 25, 40 and 56 weeks age. No Genotype  ambient temperature interactions were found except for body weight and egg deformation. Chickens at thermoneutral temperature produced significantly heavier eggs than those of heat-exposed (60 g vs. 54 g). Hen-housed egg production of controlled chickens was significantly higher than those of heat-stressed (76.8% vs. 66.2%). Daily egg mass production at thermo-neutral and heat stressed chickens was 46 g and 35.8 g, respectively. Feed consumption in heat-stressed and thermo-neutral chickens was 109 and 80.8 g, respectively. Shell thickness, breaking strength and Haugh units were significantly reduced in heat-stressed chickens. Among heat-exposed chickens, the NH had the highest body weight while the LW produced 10% more eggs than the group average. The heat-induced effect on shell quality traits was lowest in LW chickens. The results from this study indicated that the magnitude of heat stress was breed dependent in which LW and NH genotypes demonstrated improved thermo-tolerance.

Grain quality determination by means of near infrared spectroscopy in Jatropha curcas L.

Jatropha curcas L. (JCL) is an important energy plant which has received great attention in recent years for its utilization in biodiesel production and its high potential for greening and rehabilitation of wastelands. Breeding, farming and industrial processing of JCL need rapid and efficient methods to determine quality parameters associated with the value of the oil, press cake and biodiesel. Wet chemistry analyses are time consuming and expensive and near-infrared spectroscopy (NIRS) might be a suitable method for the analysis of large numbers of samples. Our main goal was to investigate the potential of NIRS to determine grain quality parameters in bulk JCL samples. We concluded that NIRS has a high potential for determining concentrations of oil, protein, ash, stearic, oleic, linoleic, linolenic and arachidic acids in the kernel fraction of JCL grains. The precision of NIRS-based phorbol ester determination could be improved by excluding samples with phorbol ester <0.1mgg−1. NIRS-based prediction of shell quality traits proved to be less accurate than for kernel traits.

Productive Performance and Egg Quality of Brown Egg-Laying Hens in the Late Phase of Production as Influenced by Level and Source of Calcium in the Diet

A total of 1,152 Lohmann Brown laying hens were used to study the influence of level (3.5 and 4.0%) and source (coded FIN, COA, and OYS) of Ca in the diet on productive performance and egg quality from 58 to 73 wk of age. The FIN diet contained all the Ca carbonate as fine limestone (LIM). In the COA and OYS diets, 40% of the fine LIM was substituted with either coarse LIM or oyster shell. Each treatment was replicated 8 times (24 hens). Productive performance and egg quality traits were recorded every 4 wk, and tibia characteristics and shell quality traits were determined at 73 wk of age. An increase in Ca intake from 4.08 to 4.64 g/hen per day improved egg production (71.2 vs. 74.9%; P < 0.001), egg mass (49.0 vs. 51.4 g; P < 0.05), and feed conversion ratio (2.43 vs. 2.30 kg of feed/kg of egg; P < 0.001). In addition, an increase in Ca intake improved shell weight (9.98 vs. 10.20%; P < 0.05), shell thickness (0.342 vs. 0.351 mm; P < 0.01), and shell density (82.0 vs. 83.8 mg/cm2; P < 0.001). Calcium source had no effect on productive performance, tibia characteristics, or egg quality except for shell density, which was greater for hens fed COA than for hens fed FIN, with hens fed OYS being intermediate (81.9 vs. 84.0 vs. 82.7 mg/cm2, respectively; P < 0.05). It was concluded that Brown egg-laying hens in the late phase of production require more than 3.5% Ca in the diet (4.08 g of Ca/hen per day) and that the substitution of 40% of fine LIM with COA or OYS does not affect productive performance and has little impact on shell quality and tibia characteristics.

The Effects of Phytase and Different Level of Dietary Calcium and Phosphorous on Phytate Phosphorus Utilization in Laying Hens

2 Abstract: This experiment was conducted to study the effects of different levels of phytase (0, 500 and 1000 FTU/kg diet), calcium (2.275 and 3.25 percent) and available phosphorus (0.175 and 0.25 percent) on phytate phosphorus utilization in laying hens. One hundreds ninety two 30-week age White Leghorn (Hy-line W-36) laying hens were randomly allocated in cages for 12 dietary treatments with arranged of 3*2*2 factorial experiment with four replicates and four hens per replicate. The experimental period lasted 90 days, when the age of hen was 42 weeks. Dietary phytase caused a significant (P<0.05) increase in feed consumption, feed conversion ratio, tibia ash weight, tibia ash percentage, tibia phosphorus, plasma phosphorus and phosphorus digestibility. However, dietary phytase caused a significantly (P<0.05) decrease in plasm a alkaline phosphatase activity and excreta phosphorus percentage. Also phytase had no beneficial effect on egg shell quality traits. Available phosphorus levels had significant effect (P<0.05) on tibia ash weight and tibia ash percentage. Reduction dietary available phosphorus caused a significant (P<0.05) decrease in feed consumption. Effect of dietary calcium were significant (P<0.05) on tibia ash weight, feed consumption and plasma phosphorus. Interaction between phytase and calcium on tibia phosphorus, plasma calcium and excreta phosphorus were significant (P<0.05). Interaction between phytase and available phosphorus on tibia phosphorus were significant (P<0.05). Overall, it could be concluded that in low phosphorus diet which food consumption is low, phytase would increase food consumption as well as retention of phosphorus in bones. Also, the lower excreta of phosphorus by using phytase could decrease pollution.

Recent advances in the assessment of eggshell quality and their future application

Any approach which aims to improve the quality and safety of eggs, is of limited value unless it can relate to the incidence of breakages in the field, and can be applied either directly to breeding programmes or used as online tools for quality assurance. Online systems require the method of assessment to be non-destructive. This is probably not so important for breeding companies who tend to gauge the usefulness of an eggshell quality measurement by its ease of measurement, its heritability and, its genetic correlation with other phenotypic traits. Historically, qualitative measures such as shell breaking or puncture strength, non-destructive deformation and specific gravity have been widely adopted as tools in selection programmes. The dynamic stiffness is a novel eggshell quality measurement, which could be utilised by poultry breeders as it has a moderate heritability and high genetic and phenotypic correlation with other shell quality traits including eggshell breaking strength. This non-destructive measurement could also be applied on-line to monitor shell quality. An alternative approach is to use genetic markers as tools to aid conventional breeding programmes where an important eggshell quality trait is practically too difficult or expensive to fully exploit. Marker-assisted selection for the genes coding for organic matrix proteins may provide a way of incorporating other beneficial egg quality traits into selection programmes in the future.

Influence of dietary osteolathyrogenson the eggshell quality of laying hens

1. Laying hens were fed osteolathyrogens, either semicarbazide hydrochloride at 0.3 or 0.4 g/kg or β-aminopropionitrile fumarate at 0.5 or 0.6 g/kg diet to examine their effects on eggshell quality. 2. Shell quality characteristics considered for evaluation were shell surface area, shell thickness, shell weight, percentage shell, shape index and the specific gravity of eggs. Measurement of shell quality traits revealed that the hens fed osteolathyrogens laid eggs with significantly lower specific gravities and proportion of shell by weight. These differences were not explained by differences in shell thickness or weight or the shape index of eggs. 3. It was concluded that osteolathyrogens cause hens to lay eggs with poor shell quality and such eggs are weak and fragile.

The Effect of Different Levels of Vitamin C and Cholecalciferol with Adequate or Marginal Levels of Dietary Calcium on Performance and Eggshell Quality of Laying Hens

Three experiments were conducted to determine whether shell quality, bone mineralization, and other production traits could be improved by adding vitamin C (ascorbic acid) to laying hen diets. The period of each experiment was 12 wk. Experiment 1 consisted of a 2 × 2 × 3 factorial design with two levels of Ca (2.8 and 3.8%), two levels of cholecalciferol (vitamin D3; 2,200 and 4,400 IU/kg diet), and three levels of vitamin C (0, 125, and 250 ppm). Experiment 2 consisted of a 2 × 3 × 2 factorial design with two levels of Ca (2.8 and 3.8%), three levels of vitamin D3 (250, 500, and 2,000 IU/kg diet), and two levels of vitamin C (0 and 250 ppm). Experiment 3 consisted of a 2 × 4 factorial design with two sources of vitamin D3 (12.5 μg vitamin D3/kg diet or 12.5 μg 25-OH-D3/kg diet) and four levels of vitamin C (0, 250, 500, and 1,000 ppm). Calcium level was kept constant at 3.5% for all the diets in Experiment 3.Production performance was not influenced by dietary treatments in Experiment 1. In Experiment 2, feed conversion was improved (P < 0.05) due to increasing the dietary Ca, and egg weight and egg size were increased (P < 0.05) due to adding 250 ppm vitamin C to the diet. In Experiment 3, albumen quality was increased by the addition of 1,000 ppm vitamin C to the diet. Egg specific gravity was increased in Experiments 1 and 2 only, due to increasing the Ca level (P < 0.05). In Experiment 2, increasing the Ca level and increasing the vitamin D3 level from 250 to 2,000 ppm reduced (P < 0.05) the number of cracked eggs, but incidence of cracked eggs was increased with the addition of 250 ppm vitamin C to the diet. In Experiment 1, plasma level of l,25(OH)2D3 was greater (P < 0.05) for hens fed 2.8 than 3.8% Ca, but blood acid-base balance was not influenced by dietary regimens. Bone ash was not influenced by dietary treatments in any of the experiments. The data indicated that a supplemental level of vitamin C had no beneficial effects on shell quality and bone mineralization under the conditions of the current experiments.

Prediction of genetic gains in body weight, egg production and shell quality traits in the Brown Tsaiya laying duck (Anas platyrhynchos)

(Anas platyrhynchos). Les gains genetiques attendus et les reponses genetiques predites du poids de l'oeuf et du poids corporel a l'âge de 40 semaines (EW40, BW40), du nombre d'oeufs pondus jusqu'a l'âge de 52 semaines (NEGG52 ), de la solidite de la coquille aux âges de 30 et 40 semaines (ES30 ou ES40) chez la cane pondeuse Tsaiya Brune selectionnee pendant cinq generations ont ete calcules. La selection par niveaux independants etait basee sur un premier choix des 50% meilleures femelles d'apres leurs valeurs individuelles d'un indice de selection massale sur les trois caracteres EW40, BW40, NEGG52 et sur un deuxieme choix portant sur les valeurs individuelles de ES30 (deux premieres generations) puis de ES40 a partir de la troisieme generation. Les reproducteurs mâles etaient choisis de facon comparable a partir de l'information sur leurs soeurs. Au total, 3482 femelles et 2093 mâles ont ete etudies. Pendant les quatre premieres generations, en moyenne 25,6% des femelles et 12,2% des mâles furent selectionnes. A partir des parametres genetiques de la population de base, les gains genetiques attendus ont ete calcules. Les reponses genetiques par generation ont ete estimees par ailleurs a partir des moyennes des predicteurs de valeurs genetiques du BLUP modele animal, en calculant la regression des moyennes en fonction du numero de generation. Les reponses par generation sont de + 0,177g (EW40); de + 8,029g (BW40); de + 0,935 oeufs (NEGG52); de + 0,017 kg/cm 2 (ES30); de + 0,014 kg/cm 2 (ES40). Ces valeurs correspondent au gain genetique attendu pour NEGG52, elles sont plus fortes pour BW40 et plus faibles pour ES30 and ES40. Il est montre que, par rapport a la methode de selection qui a ete appliquee et avec la meme intensite de selection chez les canes (i = 1 1 , 271), la selection avec contraintes sur un indice de selection massale ou un indice genetique sur quatre caracteres pourrait multiplier le gain genetique attendu de NEGG52 par 3,5 et 5,7 respectivement, tout en maintenant constant le poids de l'oeuf (EW40) et le poids corporel (BW40).

Prediction of genetic gains in body weight, egg production and shell quality traits in the Brown Tsaiya laying duck (Anas platyrhynchos)

Prediction of genetic gains in body weight, egg production and shell quality traits in the Brown Tsaiya laying duck (Anas platyrhynchos)