The Response of Layer Hen Productivity and Egg Quality to an Additional Limestone Source when Offered Diets Differing in Calcium Concentrations and the Inclusion of Phytase

Laying hens require substantial quantities of calcium (Ca) to maintain egg production. However, maintaining recommended dietary Ca through inclusion of limestone may impede nutrient digestibility, including that of other minerals. It was hypothesized that providing a separate source of dietary Ca in the form of limestone grit would preserve Ca intake of hens offered diets containing suboptimal Ca concentrations. Furthermore, the impact of dietary phytase at a “superdosing” inclusion rate on the voluntary consumption of limestone grit was evaluated. One hundred and forty-four laying hens (19 weeks of age) were assigned to one of six dietary treatments in a 3 × 2 factorial arrangement comprising three dietary Ca concentrations (40, 30, and 20 g/kg) and ±dietary phytase (3500 FYT/kg diet) on an ad libitum basis for six weeks. Limestone grit (3.4 ± 1.0 mm) was provided to all hens ad libitum. Hens offered diets containing phytase consumed significantly less limestone grit p = 0.024). Egg weight, rate of lay, and egg mass were unaffected by dietary treatment (p > 0.05). Egg shell weight % (p < 0.001), shell thickness (p < 0.001), and shell breaking strength (p < 0.01) decreased in line with dietary Ca levels. In summary, dietary superdosing with phytase reduced the consumption of a separate limestone source in individually housed, early lay ISA Brown hens. Egg shell quality variables but not egg production worsened in line with lower dietary Ca levels.

Animal contests and microplastics: evidence of disrupted behaviour in hermit crabs Pagurus bernhardus

Microplastics are ubiquitous in global marine systems and may have negative impacts on a vast range of species. Recently, microplastics were shown to impair shell selection assessments in hermit crabs, an essential behaviour for their survival. Hermit crabs also engage in ‘rapping’ contests over shells, based on cognitive assessments of shell quality and opponent fighting ability and, hence, are a useful model species for examining the effects of microplastics on fitness-relevant behaviour in marine systems. Here, we investigated how a 5-day microplastic exposure (25 microplastics/litre) affected the dynamics and outcome of 120 staged hermit crab contests. Using a 2 × 2 factorial design, we examined how microplastics (i.e. presence or absence) and contestant role (i.e. attacker or defender) affected various behavioural variables. Significantly higher raps per bout were needed to evict microplastic-treated defenders when attackers were pre-exposed to control conditions (i.e. no plastic). Also, significantly longer durations of rapping bouts were needed to evict control-treated defenders when attackers were pre-exposed to microplastics. We suggest that microplastics impaired defenders' ability to identify resource holding potential and also affected attackers’ rapping strength and intensity during contests. These impacts on animal contests indicate that microplastics have broader deleterious effects on marine biota than currently recognized.

Effects of farm location on Vibrio parahaemolyticus and V. vulnificus levels in oysters after desiccation and resubmersion in the northern Gulf of Mexico

Desiccation is a routine farming practice utilized in off-bottom oyster aquaculture to reduce biofouling organisms and improve shell quality. This practice can increase Vibrio parahaemolyticus and V. vulnificus levels, leading to increased risk of illness for raw oyster consumers. Previous resubmersion studies were performed in geographic proximity to one another, so to better understand the broader applicability of resubmersion, the next step was to perform concurrent studies in multiple geographic locations within a region. This study evaluated the effect of variations in geographic location on the recovery time needed for elevated vibrio levels to return to ambient levels in desiccated oysters after resubmersion at Gulf Coast farms. Two trials were performed between May-August 2019 at sites spanning ~100 km: three in Alabama and one in Florida. Oysters were deployed in OysterGro cages at each location, two weeks prior to each trial, then either desiccated for 24 h or remained submersed as controls. Triplicate samples were taken prior to and immediately following the desiccation period, as well as 7 and 14 d post-resubmersion. Total and pathogenic ( tdh +/ trh +) V. parahaemolyticus , and V. vulnificus levels were determined using most probable number (MPN) real-time PCR. Vibrio levels increased by 0.23-3.50 log MPN/g after desiccation. Recovery times varied among geographic locations by trial and Vibrio spp., with all vibrio counts recovering to levels not significantly higher than those in control oysters within 7-14 days of resubmersion (p≥0.06). These results suggest a 14-day resubmersion period of cultured oysters allowed vibrio levels, elevated due to routine handling, to return to ambient levels at all farm sites studied.

Transcriptome analysis revealed the effect of selenium yeast on improving eggshell quality in aged laying hens

Background Egg internal and eggshell quality were deteriorated in aging laying hens. Improving egg and shell quality can prolong the laying cycle. Although, selenium yeast (SY) has been found with the potential to enhance the laying performance and egg quality, the underlying mechanisms have not been investigated. Therefore, we investigated the effect and molecule mechanism of selenium yeast on egg and shell quality in aged laying hens. Methods Three hundred 76-week-old Jing Hong laying hens were divided into four equal treatments and fed with Se-deficient diet (SD), 0.15, 0.30, 0.45 mg/kg selenium yeast diet (SY0.15, SY0.30 and SY0.45). At the end of the trial, we evaluated the plasma and tissue selenium content, plasma antioxidant capacity and egg quality. Transcriptomic analysis was performed to investigate the boosting effect of selenium yeast on eggshell quality. The weighted gene co-expression network analysis (WGCNA) analysis was performed to screen out the key candidate genes related with eggshell quality affected by selenium yeast. Results Dietary selenium yeast supplementation enhanced the eggshell strength (SY0.45) (P < 0.01) and reduced the shell translucence (SY0.15, SY0.30 and SY0.45) to ameliorate the eggshell quality. Moreover, body Se status and plasma antioxidant capacity were significantly enhanced by selenium yeast supplementation (P < 0.05), and showed a dose-dependent effect. Transcriptomic and WGCNA analysis identified some key candidate genes involved in eggshell quality including cell migration inducing hyaluronidase 1 (CEMIP), ovalbumin (OVAL), solute carrier family 6 member 17 (SLC6A17), solute carrier family 13 member 5 (SLC13A5), proopiomelanocortin (POMC) and proenkephalin (PENK). Functional enrichment analysis revealed that selenium may alter the biological process including eggshell mineralization, ion transport and laying period to affect eggshell formation. Conclusion Selenium yeast enhanced eggshell strength and reduced the shell translucence by improving antioxidant capacity, selenium status, and regulating the processes of shell mineralization, ion transport and laying period. These findings provide a novel molecule biomarker for affecting eggshell quality regulated by selenium.

EVALUATION OF CALCIUM CARBONATE CONTENT IN EGGSHELLS OF AVIAN, TURTLE, SNAIL, AND OSTRICH USING CHEMICAL ANALYSIS AND SCANNING ELECTRON MICROSCOPY

In the present study, different eggs were collected and analyzed from five various animal species: European pond turtle (Emys orbicularis (Linnaeus, 1758)), giant African land snail (Achatina fulica (Bowdich, 1822)), common ostrich (Struthio camelus (Linnaeus, 1758)), white, light-brown, and dark-brown laying hen (Gallus gallus domesticus (Linnaeus, 1758) and European quail (Coturnix coturnix (Linnaeus, 1758). The typical mineral shell mainly composed of the calcite polymorph of CaCO3 but the eggshell consists of membranes, that composed mainly of proteins. The shell quality also could be assigned by several external and internal factors such as oviposition time, animal genotype and age, housing system (for poultry), and mineral nutrition complex. The CaCO3 content was determined by the standard titration method, coz the titration could provide a reliable method for evaluation of CaCO3 content in different types of eggshells. The structural surface characterization of eggshells was performed by scanning electron microscopy (SEM) with a field emission gun. In terms of chemical composition, ostrich eggshells generally did not differ much from those of laying hen, turtles, giant snails, or quail eggs, but the concentration of calcium carbonate was the highest. The average calcium carbonate content of various eggshells is between 84 and 98%. The thickness of the eggshell ranges from 0.08 to 1.89 mm, and it is not the same over the entire surface of the egg. At the sharp end of the egg, the shell is slightly thicker than at the blunt end. The purpose of this study was to study the quantitative content of calcium carbonate in various eggshells of different animals to draw further conclusions in which animals the eggshell contains the maximum amount of biological calcium carbonate.

Dual-Purpose Poultry in Organic Egg Production and Effects on Egg Quality Parameters

Egg laying genotypes have been selected for generations due to their high yield and egg quality, resulting in efficient feed utilization and low body weight; hence, they are not suitable for meat production. This imposes an issue for the male layer chicks, which are killed at one day old. Because of ethical and food waste concerns, the search for suitable dual-purpose genotypes in order to avoid euthanasia of male day-old chicks has intensified. The aim of the present study is to evaluate potential dual-purpose genotypes for their egg quality compared to a representative egg laying genotype. Three dual-purpose genotypes with divergent characteristics were evaluated: genotype A represented an experimental crossbreed based on a broiler type male and an egg layer female, genotype B was a pure breed, and genotype C was a crossbreed of a layer type. These were compared to a control genotype D, which was an egg layer. Eggs were collected six times during the period of 21–54 weeks of hen age, i.e., a total of 1080 shell eggs were analyzed. Examined parameters were weights of egg, shell, yolk, and albumen, by calculating their relative proportions. Shell quality was assessed by shell strength, shell stiffness, and shell thickness. Yolk quality was determined as yolk color and inclusions of blood and meat spots, and albumen quality was evaluated in terms of pH and dry matter (DM) content. The egg layer genotype produced the smallest eggs with least blood and meat spot inclusions compared to that produced by the three dual-purpose genotypes. Shell quality was superior for the layer genotype. However, the experimental genotype A laid eggs of comparable shell quality, albumen DM, and yolk weight, but also with the darkest and most red-yellow colored yolk. The two other dual-purpose genotypes produced eggs of low-medium quality. In conclusion, the genotype A could serve as dual-purpose genotype from an egg quality perspective.

Effect Of Length Of Lay Of Nigeria Indigenous Chickens On Their Egg Composition And Shell Quality

Three hundred and thirty eggs collected from the second to the seventh month of production, from a flock of the Nigeria indigenous (NI) chickens, were analysed to determine the effect of the length of lay on egg composition and shell quality. The weights of the whole egg and its components as well as shell thickness were measured monthly while the proportion of the various components; egg shape index, shell density and shell weight per surface area were calculated. The results showed that egg weight, albumen weight and % albumen increased (P<0.05) with length of lay by 2.6g, 3.5g, 3.5g and 5.6% respectively between 2nd and 7th months. The change in the weight of the yolk, shell and egg shape index was not significant (P>0.05) between the 2nd and 7th months while % yolk, % shell, shell thickness and the shell weight per surface area decreased (P<0.05) by 4.2%, 0.64%, 0.04mm and 0.003g respectively within the same period. Strong phenotypic correlations were observed between the weights of the whole egg and the albumen (r=0.81), shell (r=0.63) and yolk (r=0.46) and also between shell thickness and its weight per surface area (r=0.81). These results indicate that egg size increased as the NI hen advanced in lay. Eggs laid in the 6th and 7th months contained more albumen than those laid earlier and the shell thickness decreased as the hens advanced in lay thus making them more liable to breakage.

THE EFFECT OF AGE OF BIRD ON SHELL QUALITY AND COMPONENT YIELD OF EGGS

The effect of age of birds on shell quality and yield components of egg was studies. The birds’ egg were 25, 30, 58 or 78 weeks. The egg’ weight increased by 9.92%, 26.43% and 31.46% for birds at 30, 58 and 78 weeks, respectively. While the shell weight was found to increase by 15.10%, 34.55 and 30.44% for birds at 30.58 and 78weeks, respectively. The yolk and albumen weights were found to increase by 4.05%, 11.39%, 44.72%, 18.06% and 44.72%, 24.41% for hens at 30, 58 and 78 weeks old respectively. The yolk albumen ratio was highest (0.478± 0.12) with egg laid by 58 increase in the age of birds

The reasons for the deterioration of chicken eggshell quality at high temperatures: a review

In hot-climate regions high ambient temperature is one of the main problems of poultry farming. It is a reason for large financial losses caused by a significant decrease in the livability and productivity of poultry and the quality of products. Poor shell quality results in increased egg breakage and cracking. Such eggs lose the abilities for long-term storage or incubation and their market price is become significantly (1.5-3-fold) reduced. In the review presented the biological role of the eggshell, certain aspects of its formation, and the main reasons for the deterioration of eggshell quality in high ambient temperatures are discussed. It was shown that the eggshell quality depends on the genotype, age, feeding, health status, management conditions, etc. High ambient temperatures (above 32-35 °C) disrupt the process of eggshell formation and leads to a significant decrease in its weight, thickness, and strength. The negative impact of high ambient temperature on eggshell quality is associated with a complex set of problems, including low feed intake by hens, acid-base and mineral imbalances, physiological disorders in the endocrine system and other organs and mechanisms involved in the process of eggshell formation. The understanding of these reasons gives an opportunity for the development and implementation of targeted interventions and enables the minimization of negative impact of heat stress on eggshell quality and the efficiency of the commercial egg production.