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The dog is a so far unique species to study interspecific communication and a promising evolutionary model for preverbal human communication. Recently cats were reported to show some similar skills to dogs. Here we directly compared both the testability and the success of companion dogs and cats in relying on human distal pointing gestures. Due to differences in their domestication, social and ecological background, and developmental processes, we expected better performance from dogs compared to cats. Using an object-choice task, cats made considerably fewer choices than dogs in the laboratory environment, and their tendency to make a choice declined during trials. They were slightly more testable at home, where their willingness to choose did not decrease over time. Dogs made more successful choices than cats, both at the group and individual level, irrespective of the type of the pointing gesture. Older cats were more successful. Despite the two species' rather similar role nowadays as human companions, our results support previous findings suggesting that, compared to the dog, the cat is a less ideal model to study some human communicative abilities in a laboratory environment. [ABSTRACT FROM AUTHOR]

The dog is a so far unique species to study interspecific communication and a promising evolutionary model for preverbal human communication. Recently cats were reported to show some similar skills to dogs. Here we directly compared both the testability and the success of companion dogs and cats in relying on human distal pointing gestures. Due to differences in their domestication, social and ecological background, and developmental processes, we expected better performance from dogs compared to cats. Using an object-choice task, cats made considerably fewer choices than dogs in the laboratory environment, and their tendency to make a choice declined during trials. They were slightly more testable at home, where their willingness to choose did not decrease over time. Dogs made more successful choices than cats, both at the group and individual level, irrespective of the type of the pointing gesture. Older cats were more successful. Despite the two species' rather similar role nowadays as human companions, our results support previous findings suggesting that, compared to the dog, the cat is a less ideal model to study some human communicative abilities in a laboratory environment. [ABSTRACT FROM AUTHOR]

We proposed here a non-destructive technology for pre-sorting eggs into subclasses characterized by a specifical acceptable shelf life and quality requirements. Egg characteristics were identified suiting a predictive model for controlling storage periods. Accordingly, the relationships of egg parameters were assessed, with weight loss (ΔW) during storage being the best indicator of changes in egg contents variables. Using changes in ΔW, we established three indicators with the maximum effect on fast egg drying and shrinkage. These included egg weight (W), egg volume-to-surface area ratio, and air cell diameter. The relationship formulae were derived to estimate the ΔW value accurately. This approach enables to judge regarding the potential of each particular egg subclass for its acceptable weight shrinkage and assign an optimal storage period for it. The proposed non-invasive analytical method can be implemented in industrial conditions for both table and hatching eggs with the available set of automated technological equipment. [ABSTRACT FROM AUTHOR]

Herein we examined the effects of yolk size and ovulation order on the fertilisation of yolks within doubleyolked (DY) duck eggs. Single-yolked (SY) duck eggs had high fertility (89.98%), whereas in DY duck eggs fertility was low (51.9% yolks). The yolks closer to the airspace (Yolk 1) inDYeggs had higher fertility (68.82% vs 34.98% for Yolk 2; P<0.001). When only one of the two yolks was fertilised, Yolk 1 was fertilised in 99.12% of those eggs. Yolk 1 is presumed to be the first ovulated. The higher fertility of Yolk 1 is consistent with a primacy effect where the first ovulation has a higher probability of achieving fertilisation. SmallDY eggs within the normal SY egg weight range (75-104.9 g) had significantly lower yolk fertility (47.91%; n=550) compared with large (≥105 g)DYeggs (54.56%; n=768; P<0.001). Yolk 1 fertility was lower in small compared with large DY eggs (64.18% vs 72.14%, respectively; P=0.003). Although Yolk 2 fertility was low, it was not affected by egg size. DY eggs with zero fertilised yolks were significantly lighter than DY eggs with one (P=0.007) or two (P<0.001) fertilised yolks (i.e. larger DY eggs were more likely to have fertilised yolks). Larger eggs (≥105 g) have larger yolks and the evidence here shows that an optimal yolk size is a significant positive factor in achieving fertilization by dislodging spermatozoa, after ovulation, from their storage sites. [ABSTRACT FROM AUTHOR]

Multiple-yolked avian eggs, and especially triple-yolked (TY) eggs, are rare. Over two years, 48,224 duck eggs (Anas platyrhynchos domesticus) were individually candled and seven (0.0145%) TY eggs were identified in a commercial breeding and incubation environment. When compared with double-yolked eggs (Salamon and Kent, 2016) their mean weight, length, width and shape index did not differ, but their dimensions were greater than for single-yolked duck eggs. Yolk fertility in the TY eggs was low (33.33%), and this was attributed to smaller yolk size and early ovulation and/or follicle immaturity. By day 8 of incubation, fertile yolks were positioned next to the airspace. Egg 5 contained one fertile yolk, and the embryo developed to enter the airspace, was consuming all three yolks, but failed to hatch. [ABSTRACT FROM AUTHOR]

The present investigation was aimed at predicting a still (i.e., dead) vs. live embryo within a hatching goose egg by measuring the eggshell cooling rate. For this, we daily measured the temperature (T) values on the shell surface of goose eggs after they were removed from the incubator and during further natural cooling. T was recorded every 0.5 h for further 1.5 h of cooling. It was possible to recognize eggs with dead embryos using the combination of T , egg weight (W), and surface area (S). The resultant indicator (TS / W) was called specific temperature index (STI). The mathematical relationship using STI measurements between Days 8–13 facilitated 80 % correct identification of the eggs with dead embryos. Additionally, we derived mathematical dependencies for shell weight (W s) and thickness (t) by utilizing the values of W , egg volume (V), S , the average T of all measurements taken, as well as the drop in T during 1.5 h of natural cooling. The key advantage of these parameters was their measurement and/or calculation by applying non-destructive methods. The integrated application of these parameters resulted in achieving high calculation accuracy as judged by correlation coefficients of 0.908 for W s and 0.593 for t. These novel mathematical models have the potential to decrease hatching waste by predicting embryo viability. Our research will add to a toolkit for non-invasive egg assessment that is useful in the poultry industry, research on eggs, and engineering. [Display omitted] • We aimed at predicting still (dead) vs. live embryos in goose eggs by cooling rate. • We measured shell surface temperature (T) during natural cooling for 1.5 h. • Specific temperature index was derived to predict correct identification of eggs. • We propose this index to predict eggs with dead embryos and reduce hatching waste. [ABSTRACT FROM AUTHOR]

A bird's egg has a variety of distinct physical characteristics that assure its functionality as a naturally engineered 'packaging' for the growing embryo. It also contains essential nutrients for human food. Egg density (D) is one such crucial physical parameter frequently involved in studies pertaining to its interrelationship with the quality of both table and hatching eggs. In this investigation, we conducted more in-depth experiments based on theoretical research and simulation modelling methods. This specifically involved the possible use of D to predict the values of other egg parameters. The theoretically derived equation for D enabled us to reduce a number of parameters that affect the value of D. Herewith, we suggested that it would be more suitable for planning experiments and promising for studying eggs of various bird species to use parameter ratios rather than their original values. On the basis of simulation methods, we generated and analyzed an extensive database of 'virtual' chicken eggs that included all possible variations of the parameters from the proposed D equation. We established that the most influential factor on D is the density of egg interior (D i) and the most predictable parameter by the D value is the shell thickness (T). Approximation of the obtained data on the dependence of T on D led to a prediction accuracy of R = 0.68. We also demonstrated that the ratio D i / D was more dependent on the ratio of shell volume to whole egg volume and can be a very promising criterion for developing a new avenue of research on pre-incubational sorting of eggs. To refine the accuracy of prediction using this criterion, a further development of more efficient and precise methods for non-destructive measurement of T and D s will be required. • We defined an equation for egg density using its other physical variables. • Based on simulation modelling methods, a database of virtual eggs was generated. • A value of egg density basically depended on the density of its interior. • A formula for recalculation of the shell thickness from egg density was deduced. [ABSTRACT FROM AUTHOR]

The present study was aimed to seek algorithms for prior identification of goose eggs unsuitable for incubation that, otherwise, turn into to hatching waste. These included infertile eggs and those in which the embryo did not survive by the hatch time. The algorithm development was based on egg parameter measurements taken before and during incubation. As a result, a complex of egg's geometrical parameters, i.e., its length, breadth and diameter at a point 1/4 of the length from the pointed end, were established as the best predictors and used for producing four novel indicators. The above parameters were incorporated into the first indicator called the Emergency Geometrical Index (EGI). Its use prior to incubation enabled to correctly identify 14–26% of eggs within the hatching waste category. The second indicator was the ratio of air cell volume to egg weight. The respective preincubation measurements enable to correctly identify ∼38% of unsuitable eggs. When combining the first two indicators, the third one was developed and called the Emergency Hatchability Index (EHI), with the correct identification rate being ∼65% of unsuitable eggs. Egg density (D) during incubation was proposed as the fourth promising indicator. This was expressed as the tangent of the slope for a trend line based on D data calculated for successive days of incubation. Collectively, the proposed four indicators and few other new methodological approaches used for their derivation will be instrumental in predicting hatchability of goose and other poultry eggs before incubation to reduce hatching waste. • Egg parameter measurements were used to define goose eggs suitable for incubation. • Four mathematical models were developed to predict correct identification of eggs. • The new indicators can be used to predict hatchability and reduce hatching waste. [ABSTRACT FROM AUTHOR]

Density of egg interior (D i) can be considered as universal index of the quality characteristics of the whole egg. Here, we implemented a theoretical and experimental approach to developing a method for non-invasive estimation of D i. The derived equation showed its dependence on the egg density (D) and the content of the shell in the egg, the latter being assessed as weight and volumetric ratios. We found that, for a fairly accurate prediction of D i , it is sufficient to include two parameters in the calculation, i.e., D and the non-destructive shell deflection. These were combined into one empirical equation that showed the calculation accuracy within this experiment at the level of R = 0.966. Determination of D i using non-destructive methods will allow for developing a number of applications, e.g., pre-incubation egg sorting, determining the conditions and duration of egg storage, and the quality rating of table eggs by internal contents. • We derived a theoretical equation for interior density, a vital egg quality trait. • This depends on egg density, as well as weight and volume fractions of the shell. • Experimental tests showed a high correlation of egg density with interior density. • Egg interior density model accuracy increases with adding shell deformation. • Two empirical formulae were also obtained for calculating egg interior density. [ABSTRACT FROM AUTHOR]

In general, avian species produce clutches of more than one egg. Differential investment in egg weight and hormone levels is possible and their effects on development and behaviour can be measured. Here we investigated changes in three hormones (testosterone, T; androstenedione, A4 and progesterone, P4) in the outer layer of yolks of infertile domestic goose eggs over the course of a laying season. There was a significant change in the concentration of all three hormones: T and P4 increased in a linear manner across the season whilst A4 increased until mid season and then steadily decreased. The correlation between T and P4 (r = 0.613, P<0.001), and between T and A4 (r = 0.746, P<0.001) were both positive, but the relationship between A4 and P4, while positive was not strong (r = 0.379, P<0.001), although still significant. The increase in P4 over the laying season is consistent with the transition from a laying to a broody state. The increase in T is consistent with a trade-off for the seasonal decline in egg weight. [ABSTRACT FROM AUTHOR]

In waterfowl farms used for producing meat and eggs, a problem of discerning double-yolked (DY) and single-yolked (SY) eggs is rather actual. While in some parts of the world DY eggs are popular as a food product, DY eggs are undesired for hatcheries due to their lower fertility and poorer hatchability. After examining the morphological parameters of duck and goose DY and SY eggs, we determined a suite of their measured and calculated variables. We developed mathematical formulae that can be used to calculate the estimated quantity of yolks in duck or goose eggs. In this experiment, this innovative analytical approach enabled us to achieve 8.4% of erroneously placed SY eggs in a DY 'basket' for ducks and 3.2% for geese. We also considered options to increase further their identification accuracy. This study provides an instrumental prerequisite for developing respective practical analytical techniques for sorting waterfowl SY vs DY eggs. • Being food products, duck/goose eggs are subject to math and engineering research. • Quantity of yolks in them can be predicted based on their physical characteristics. • We introduce here an innovative approach to predict single- and double-yolked eggs. • The formulae are applicable in areas of food research and emerging technologies. [ABSTRACT FROM AUTHOR]