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I C Dunn - One of the best experts on this subject based on the ideXlab platform.
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No evidence that selection for Egg Production persistency causes loss of bone quality in laying hens
Genetics Selection Evolution, 2021Co-Authors: I C Dunn, Dirk-jan De Koning, Heather A. Mccormack, Robert H. Fleming, Peter W. Wilson, Björn Andersson, Matthias Schmutz, Cristina Benavides, Nazaret Dominguez-gasca, Estefania Sanchez-rodriguezAbstract:AbstractBackgroundThe physiological adaptations that have evolved for Egg laying make hens susceptible to bone fractures and keel bone damage. In modern laying hen breeds, longer periods of Egg laying could result in a greater risk of poor bone quality, and selection for increased Egg Production has frequently been stated to be a cause. However, the existing literature does not support this hypothesis. To test the hypothesis that Egg Production is associated with quality, breaking strength and density of bone, genetic correlations between these traits were estimated in White Leghorn and Rhode Island Red breeds. Genetic correlations of cortical and medullary bone material chemical properties with bone quality were also estimated, in order to identify methods to improve bone quality with appropriately targeted measurement of key traits.ResultsEstimates of heritability for bone quality traits were moderate (0.19–0.59) for both White Leghorn and Rhode Island Red breeds, except for the keel bone trait, which had a heritability estimate equal to zero. There was no evidence for genetic or phenotypic relationships between post-peak Egg Production and bone quality. In the White Leghorn breed, the estimate of the genetic correlation between pre-peak Production/age at first Egg and bone quality was significant and negative (− 0.7 to − 0.4). Estimates of heritability of thermogravimetric measurements of tibial medullary bone mineralisation were significant (0.18–0.41), as were estimates of their genetic correlations with tibia breaking strength and density (0.6–0.9).ConclusionsThe low genetic correlation of post-peak Egg Production with bone quality suggests that selection for increased persistency of Egg Production may not adversely affect bone quality. Onset of puberty and mineralisation of the medullary bone, which is a specialised adaptation for Egg laying, were identified as important factors associated with the quality of the skeleton later during Egg Production. These are traits for which genetic, as well as environmental and management factors can positively impact the overall quality of the skeleton of laying hens.
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no evidence that selection for Egg Production persistency causes loss of bone quality in laying hens
Genetics Selection Evolution, 2021Co-Authors: I C Dunn, Dirk-jan De Koning, Peter W. Wilson, Björn Andersson, Matthias Schmutz, Cristina Benavides, Heather Mccormack, Robert Fleming, Nazaret Dominguezgasca, Estefania SanchezrodriguezAbstract:The physiological adaptations that have evolved for Egg laying make hens susceptible to bone fractures and keel bone damage. In modern laying hen breeds, longer periods of Egg laying could result in a greater risk of poor bone quality, and selection for increased Egg Production has frequently been stated to be a cause. However, the existing literature does not support this hypothesis. To test the hypothesis that Egg Production is associated with quality, breaking strength and density of bone, genetic correlations between these traits were estimated in White Leghorn and Rhode Island Red breeds. Genetic correlations of cortical and medullary bone material chemical properties with bone quality were also estimated, in order to identify methods to improve bone quality with appropriately targeted measurement of key traits. Estimates of heritability for bone quality traits were moderate (0.19–0.59) for both White Leghorn and Rhode Island Red breeds, except for the keel bone trait, which had a heritability estimate equal to zero. There was no evidence for genetic or phenotypic relationships between post-peak Egg Production and bone quality. In the White Leghorn breed, the estimate of the genetic correlation between pre-peak Production/age at first Egg and bone quality was significant and negative (− 0.7 to − 0.4). Estimates of heritability of thermogravimetric measurements of tibial medullary bone mineralisation were significant (0.18–0.41), as were estimates of their genetic correlations with tibia breaking strength and density (0.6–0.9). The low genetic correlation of post-peak Egg Production with bone quality suggests that selection for increased persistency of Egg Production may not adversely affect bone quality. Onset of puberty and mineralisation of the medullary bone, which is a specialised adaptation for Egg laying, were identified as important factors associated with the quality of the skeleton later during Egg Production. These are traits for which genetic, as well as environmental and management factors can positively impact the overall quality of the skeleton of laying hens.
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explanations for keel bone fractures in laying hens are there explanations in addition to elevated Egg Production
Poultry Science, 2020Co-Authors: M J Toscano, Stefanie Petow, Kathe Elise Kittelsen, Jens Peter Christensen, I C Dunn, Reiner UlrichAbstract:The current article served to provide the most up-to-date information regarding the causes of keel bone fracture. Although elevated and sustained Egg Production is likely a major contributing factor toward fractures, new information resulting from the development of novel methodologies suggests complementary causes that should be investigated. We identified 4 broad areas that could explain variation and increased fractures independent of or complementing elevated and sustained Egg Production: the age at first Egg, late ossification of the keel, predisposing bone diseases, and inactivity leading to poor bone health. We also specified several topics that future research should target, which include continued efforts to link Egg Production and bone health, examination of noncommercial aves and traditional breeds, manipulating of age at first Egg, a detailed histological and structural analysis of the keel, assessment of prefracture bone condition, and the relationship between individual activity patterns and bone health.
Enric Saiz - One of the best experts on this subject based on the ideXlab platform.
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effects of food concentration on Egg Production and feeding rates of the cyclopoid copepod oithona davisae
Limnology and Oceanography, 2013Co-Authors: Sara Zamoraterol, Enric SaizAbstract:Experiments to determine Egg Production and feeding rates of Oithona davisae were carried out under controlled laboratory conditions. From copepodite IV stage on, the animals were fed the heterotrophic dinoflagellate Oxyrrhis marina in a wide range of concentrations (from 10 m gCL 21to 286 m gCL 21), and adult females were daily monitored to study different aspects of their fecundity. Both clutch and Egg-Production rate increased with food concentration, with values from 8 to 20 Eggs for the clutch size, and from 1.8 Eggs to 6.3 Eggs female21 d21 for the Egg Production. In addition, to assess the efficiency of conversion of food intake into Egg mass, two feeding experiments were conducted. Maximum weight-specific ingestion rates (< 80% body C d21) and the Egg-Production efficiency (16%) were lower than those reported for free-spawning calanoid copepods. The fact that satiating food concentrations for feeding and Egg Production of adult females of Oithona davisae were rather low suggests an adaptation to exploit oligotrophic environments, and might explain the ecological success of the genus in situations when food becomes limiting for other groups of copepods. It is widely accepted that small copepods (, 1 mm) are important, but poorly studied components of marine pelagic communities (Turner 2004). They were often neglected from samplings in past years until several authors
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experimental records of the effects of food patchiness and predation on Egg Production of acartia tonsa
Limnology and Oceanography, 1993Co-Authors: Enric Saiz, Peter Tiselius, Per R Jonsson, Peter G Verity, Gustavadolf PaffenhoferAbstract:The effects of predation and spatial patchiness in food distribution on Egg Production of the marine Calanoid copepod Acartia tonsa were investigated in the laboratory. A postexperiment Egg Production method was developed to override the decline in number of copepods due to predation. The copepods were able to remain in food patches about 41-47% of the time, and consequently Egg Production rates were higher than expected from the average food concentration. Predation by the Calanoid copepod Labidocera aestivu tended to increase Egg Production rates of A. tonsa. The interaction of patchiness and predation resulted in relatively less time spent by A. tonsa in the food patches, probably as a consequence of conflict between hunger level and predation risk. Predation and food availability are probably the most important biological factors that influence zooplankton Production in aquatic systems (Landry 1978a; Ohman 1988; Kimmerer 1991). They determine the extent to which an animal can grow and produce viable offspring. Predation has a direct effect by the removal of prey, but it may also act indirectly by inducing changes in behavior and performance of prey (Sih 1987; Ohman 1988). Regarding food, numerous studies have analyzed relationships between concentration and quality of food, and
Diane C Bellantoni - One of the best experts on this subject based on the ideXlab platform.
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seasonal feeding and fecundity of the calanoid copepod acartia tonsa in long island sound is omnivory important to Egg Production
Hydrobiologia, 1994Co-Authors: Hans G Dam, William T Peterson, Diane C BellantoniAbstract:Many suspension-feeding copepods show omnivorous feeding behavior. However, the relative contribution to Egg Production of herbivorous and heterotrophic feeding in copepods remains an open question. In this study, we quantified pigment ingestion rates and Egg Production rates of the planktonic calanoid copepod Acartia tonsa from July to November of 1986 in Long Island Sound, a large temperate estuary. Pigment ingestion and Egg Production rates were better correlated to the > 10-µm chlorophyll size fraction than total chlorophyll. Maximum pigment ingestion and Egg Production rates were observed during the fall bloom in September. Pigment ingestion and Egg Production rates were linearly related. However, pigment ingestion rates accounted for only 48% of the variance in Egg Production rates. If female A. tonsa had fed entirely as herbivores over the course of the season, the observed gross efficiency of Egg Production, K'1 = Egg Production rate/pigment ingestion rate, in terms of nitrogen, would have been 0.68. This growth efficiency is considerably higher than the expected value, K 1 = 0.38, for this species based on laboratory studies of herbivorous feeding. We suggest that the ratio H = K 1/K' 1 is a measure of the fraction of Egg Production that is due to herbivorous feeding. Thus, we infer that herbivory accounted for 56% (0.38/0.68) of Egg Production in A. tonsa in this study. The ratio H is an useful tool in examining the relative contribution to Egg Production of herbivorous and heterotrophic feeding in copepods.
L Houchin - One of the best experts on this subject based on the ideXlab platform.
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nutrition and the regulation of Egg Production in the calanoid copepod acartia tonsa
Limnology and Oceanography, 1998Co-Authors: G S Kleppel, C A Burkart, L HouchinAbstract:The nutritional composition of the copepod diet is determined by the feeding response, often through complex interactions with the food environment. On the time scales at which studies of copepod feeding and Egg Production are typically conducted (hours to weeks), variations in the nutritional composition of the food supply may be responsible for considerable variability in Egg Production. A substantive portion of this variability can be accounted for when the nutritional composition of the diet is known. In a laboratory study in which we measured the amino and fatty acids in the diet of Acartia tonsa in six “food environments,” we detected differences in Egg Production that were apparently associated with amino acid deficiency, differences in the proportions and types of fatty acids in the diet, and differences in the kinds of food organisms taken from a mixture and in the effort required to capture a ration. Egg Production varied systematically with the concentrations of 3 fatty acids (of 18 present in the diet) and 4 amino acids (of 16 present) in the diet.
Estefania Sanchezrodriguez - One of the best experts on this subject based on the ideXlab platform.
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no evidence that selection for Egg Production persistency causes loss of bone quality in laying hens
Genetics Selection Evolution, 2021Co-Authors: I C Dunn, Dirk-jan De Koning, Peter W. Wilson, Björn Andersson, Matthias Schmutz, Cristina Benavides, Heather Mccormack, Robert Fleming, Nazaret Dominguezgasca, Estefania SanchezrodriguezAbstract:The physiological adaptations that have evolved for Egg laying make hens susceptible to bone fractures and keel bone damage. In modern laying hen breeds, longer periods of Egg laying could result in a greater risk of poor bone quality, and selection for increased Egg Production has frequently been stated to be a cause. However, the existing literature does not support this hypothesis. To test the hypothesis that Egg Production is associated with quality, breaking strength and density of bone, genetic correlations between these traits were estimated in White Leghorn and Rhode Island Red breeds. Genetic correlations of cortical and medullary bone material chemical properties with bone quality were also estimated, in order to identify methods to improve bone quality with appropriately targeted measurement of key traits. Estimates of heritability for bone quality traits were moderate (0.19–0.59) for both White Leghorn and Rhode Island Red breeds, except for the keel bone trait, which had a heritability estimate equal to zero. There was no evidence for genetic or phenotypic relationships between post-peak Egg Production and bone quality. In the White Leghorn breed, the estimate of the genetic correlation between pre-peak Production/age at first Egg and bone quality was significant and negative (− 0.7 to − 0.4). Estimates of heritability of thermogravimetric measurements of tibial medullary bone mineralisation were significant (0.18–0.41), as were estimates of their genetic correlations with tibia breaking strength and density (0.6–0.9). The low genetic correlation of post-peak Egg Production with bone quality suggests that selection for increased persistency of Egg Production may not adversely affect bone quality. Onset of puberty and mineralisation of the medullary bone, which is a specialised adaptation for Egg laying, were identified as important factors associated with the quality of the skeleton later during Egg Production. These are traits for which genetic, as well as environmental and management factors can positively impact the overall quality of the skeleton of laying hens.