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L Schifferli - One of the best experts on this subject based on the ideXlab platform.
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the effect of Egg Weight on the subsequent growth of nestling great tits parus major
Ibis, 2008Co-Authors: L SchifferliAbstract:Summary Eggs of known fresh Weight were removed from Great Tit nests shortly before hatching and artificially incubated. Four to eight chicks were returned to each nest-box on their hatching day and reared by foster parents. The effect of Egg Weight on subsequent growth was studied for 81 nestlings (13 broods), 50 of them (8 broods) up to the 17th day. Hatching success of 275 Eggs in the incubator was 67·6% and was not correlated with Egg Weight. Egg Weight had a significant effect on nestling Weight up to the 14th day. Young hatched from lighter Eggs grew more slowly at the beginning, but recovered before fledging. Mortality after fledging seemed not to be influenced by Egg Weight. Maximum Weight (mean 19 g) was attained between the 12th and the 17th day and was positively correlated with Egg Weight. The effect of brood-size (small in the experiments) on growth increased significantly with age. The range of Egg Weight for a nest had a significant effect on growth at the beginning, but a small and not significant effect after the 10th day. The growth of each brood on any particular day was expressed as a deviation from mean growth. These growth deviations, plotted against date, were similar in all nests and were not correlated with any weather data. The fledging success of 260 early broods was independent of Egg Weight, but it was positively correlated with Egg Weight in 78 late broods (data from 1965–71). The ecological importance of Egg Weight at different times of the breeding season is discussed.
F G Silversides - One of the best experts on this subject based on the ideXlab platform.
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the haugh unit correction for Egg Weight is not adequate for comparing Eggs from chickens of different lines and ages
The Journal of Applied Poultry Research, 1994Co-Authors: F G SilversidesAbstract:Abstract The Haugh unit is the accepted commercial and research standard for measuring albumen quality of chicken Eggs. This unit has been criticized because it assumes a fixed relation between Egg Weight and albumen height. However, the amount of albumen in an Egg differs between genetic strains and changes with the age of the hen. Data are presented to show that no fixed regression is adequate for comparing Eggs from hens of different strains of chickens. With the increasing age of the hen, the Weight of the Egg increases in a quadratic fashion while the albumen height decreases linearly. The Haugh unit also declines more rapidly than does the actual albumen height because of the overcompensation for Egg Weight in the Haugh unit calculation. Correlation coefficients between Haugh unit, albumen height, and the log of the albumen height were very high. When comparing Eggs from diverse groups of hens, the Haugh unit correction for Egg Weight will likely introduce more error than it will eliminate.
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is the haugh unit correction for Egg Weight valid for Eggs stored at room temperature
Poultry Science, 1994Co-Authors: F G Silversides, P VilleneuveAbstract:Abstract The Haugh unit (HU) is the measure of albumen quality used by the poultry industry, but its correction for Egg Weight has been severely criticized. The validity of the correction for Egg Weight was investigated with an unwashed, unclassified sample of 800 Eggs obtained from a commercial Egg classification station. This sample was divided into four groups, one for study immediately and the others after storage at room temperature for 1, 2, or 3 wk. After weighing, each Egg was broken and the height of the albumen was measured. Weights of the yolk, shell, and albumen were determined for each Egg, and albumen pH was determined from pooled samples of three Eggs each. Haugh units were calculated using the formula: HU = 100 log[H + 7.57 − 1.7W.37]. Statistical relationships between these variables were investigated. A weak relation (r2 = .04 to .07) between albumen height and Egg Weight was observed. Haugh unit score was dependent on albumen height (r2 = .88 to .95) but independent of either Egg or albumen Weight, except after 3 wk of storage and when all data were combined. Time in storage explained 78% of the variation in HU and 77% of the variation in albumen height. A regression model including both week and Egg Weight did not increase these R2 values. Changes in albumen quality over time in storage were described equally well by albumen height as they were by the HU score, suggesting that the HU correction for Egg Weight is unnecessary.
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research note a study relating to the validity of the haugh unit correction for Egg Weight in fresh Eggs
Poultry Science, 1993Co-Authors: F G Silversides, F Twizeyimana, P VilleneuveAbstract:Abstract Egg Weights, Weights of the major Egg components, and albumen heights were measured on Eggs from young and old flocks of the same strain of commercial layer. This allowed investigation of the relationships between these measures and Haugh unit scores (HU). The HU calculation uses a formula designed to correct the height of the albumen to a constant 56.7-g Egg. Results showed that the effect of Egg Weight on albumen height was of minor importance within flocks and inconsistent between flocks. The statistical relationship between albumen Weight and albumen height was equally weak. When all Eggs were included in one data set, both Egg Weight and albumen Weight significantly affected HU, showing that the correction for Egg Weight was not adequate. Variation in the albumen height was associated with 93 to 95% of the variation seen in HU. These data suggest that calculation of HU is not necessary for Eggs coming from one flock, and is wrong when Eggs come from different flocks. Measuring the height of the albumen is suggested as a simple replacement for the HU calculation.
P Villeneuve - One of the best experts on this subject based on the ideXlab platform.
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is the haugh unit correction for Egg Weight valid for Eggs stored at room temperature
Poultry Science, 1994Co-Authors: F G Silversides, P VilleneuveAbstract:Abstract The Haugh unit (HU) is the measure of albumen quality used by the poultry industry, but its correction for Egg Weight has been severely criticized. The validity of the correction for Egg Weight was investigated with an unwashed, unclassified sample of 800 Eggs obtained from a commercial Egg classification station. This sample was divided into four groups, one for study immediately and the others after storage at room temperature for 1, 2, or 3 wk. After weighing, each Egg was broken and the height of the albumen was measured. Weights of the yolk, shell, and albumen were determined for each Egg, and albumen pH was determined from pooled samples of three Eggs each. Haugh units were calculated using the formula: HU = 100 log[H + 7.57 − 1.7W.37]. Statistical relationships between these variables were investigated. A weak relation (r2 = .04 to .07) between albumen height and Egg Weight was observed. Haugh unit score was dependent on albumen height (r2 = .88 to .95) but independent of either Egg or albumen Weight, except after 3 wk of storage and when all data were combined. Time in storage explained 78% of the variation in HU and 77% of the variation in albumen height. A regression model including both week and Egg Weight did not increase these R2 values. Changes in albumen quality over time in storage were described equally well by albumen height as they were by the HU score, suggesting that the HU correction for Egg Weight is unnecessary.
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research note a study relating to the validity of the haugh unit correction for Egg Weight in fresh Eggs
Poultry Science, 1993Co-Authors: F G Silversides, F Twizeyimana, P VilleneuveAbstract:Abstract Egg Weights, Weights of the major Egg components, and albumen heights were measured on Eggs from young and old flocks of the same strain of commercial layer. This allowed investigation of the relationships between these measures and Haugh unit scores (HU). The HU calculation uses a formula designed to correct the height of the albumen to a constant 56.7-g Egg. Results showed that the effect of Egg Weight on albumen height was of minor importance within flocks and inconsistent between flocks. The statistical relationship between albumen Weight and albumen height was equally weak. When all Eggs were included in one data set, both Egg Weight and albumen Weight significantly affected HU, showing that the correction for Egg Weight was not adequate. Variation in the albumen height was associated with 93 to 95% of the variation seen in HU. These data suggest that calculation of HU is not necessary for Eggs coming from one flock, and is wrong when Eggs come from different flocks. Measuring the height of the albumen is suggested as a simple replacement for the HU calculation.
Henri Woelders - One of the best experts on this subject based on the ideXlab platform.
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Yolk concentrations of hormones and glucose and Egg Weight and Egg dimensions in unincubated chicken Eggs, in relation to Egg sex and hen body Weight.
General and comparative endocrinology, 2013Co-Authors: M. Aamir Aslam, Marcel Hulst, Rita A. H. Hoving-bolink, Mari A. Smits, Bonnie De Vries, Ilse Weites, Ton G. G. Groothuis, Henri WoeldersAbstract:Birds can manipulate offspring sex ratio under natural and experimental conditions and maternal hormones have been shown to be involved in this process. Studies also provided evidence for the presence of sex specific concentrations of yolk hormones in avian Eggs. These findings led to the suggestion that yolk hormones could influence genetic sex determination in birds. However, in previous studies, yolk hormone concentrations and Egg sex were studied in incubated Eggs, although incubation of the Eggs and embryonic development can alter yolk hormone concentrations and measured sex ratio. This study is the first to determine a wide array of Egg components and hen body Weight in relation to the sex of the Egg in unincubated Eggs. Egg parameters studied were yolk concentrations of testosterone, estradiol, androstenedione, progesterone, dihydrotestosterone, and glucose, and Egg Weight and dimensions. In addition, we studied the associations among all measured parameters. Associations were found between a number of yolk hormones (progesterone associated with testosterone, estradiol and androstenedione; androstenedione with testosterone; dihydrotestosterone with estradiol and androstenedione) as well as between yolk testosterone and Egg length and Egg Weight. There were no significant overall differences between male and female chicken Eggs in any of the measured Egg parameters. However, there were a few interactions such as the interaction of Egg sex with dihydrotestosterone and with hen body Weight which predicted estradiol levels and an interaction of estradiol levels with Egg width for predicting sex of Egg. Their biological relevance need, however, further study.
A J Isaacson - One of the best experts on this subject based on the ideXlab platform.
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factors affecting Egg Weight body Weight and moult of the woodpigeon columba palumbus
Ibis, 2008Co-Authors: R K Murton, N J Westwood, A J IsaacsonAbstract:Summary The heaviest clutches (2 Eggs) laid by Woodpigeons Columba palumbus in a Cambridgeshire study area weighed 30% more than the lightest. Yet the variation in Egg-Weight within clutches was less than 1 %. Irrespective of initial Weight, Eggs lost Weight at the same constant rate during incubation. Heavy Eggs hatched more successfully than light Eggs and none weighing less than 16 g hatched. There was no correlation between chicks' Weight at hatching and their Weight at day 6 during the July-September part of the breeding season. The ability to feed crop milk at this stage could compensate for low chick-Weight, but this might not be true early in the season. Weight at day 6 was correlated with the Weight at day 16 or 17. The growth pattern is discussed. Chicks in broods of one achieved a higher Weight at day 17 than those in broods of two. The survival rate both in and after leaving the nest was the same in both brood-sizes. Chick-Weight in artificially created broods of three was almost as high as in broods of two, but again data refer to the July-September period when abundant cereal food is available. Survival before and after fledging was lower in broods of three. Clutch- and Egg-Weight declined from April until September. It is suggested that this is adaptive, in that the adults produce heavier Eggs when food supplies are most difficult to collect. The critical period probably occurs during the few days when the adult must produce crop milk and the young cannot be left unattended. Thus Egg-Weight depends on the female's capacity to acquire nutrients, and is related to the needs of embryonic development and the amount of compensation in nutrient supply which can be provided immediately after hatching. But clutch-size is more related to the bird's ability to feed and rear young to the point of fledging, thereby influencing the number of offspring which survive to leave progeny. Egg-Weight and female body-Weight were positively correlated in females weighing less than 480 g but not in heavier females. First-year birds did not acquire adult Weight until midsummer and they would probably produce light Eggs if they could breed before this month. However, their gonads do not recrudesce until July and this prevents them breeding in the spring. Seasonal changes in body-Weight and fat content of adults and first-year birds are described and discussed; differences were noted between adult males and females which were considered to be adaptive. The moult is described. It begins in April and continues until November, approximately one pair of primaries being replaced per month. The moult ceases during the winter months, when it is known that food supplies become limiting. Woodpigeons lay light Eggs relative to their body-Weight but can achieve the extra parental care needed for the altricial chicks by producing crop milk. Because the moult is extended, the energy demands of moulting and breeding combined are relatively low and this enables the Woodpigeon to have a long breeding season and to moult coincidentally.
