The purpose of this research is to describe and to compare the morphology of megalopa and the first crab of four Scylla species which lives along the coast of Tungkang. The megalopa of S. serrata has dactyl lower margin on the fifth abdominal segment which is different from three other Scylla species. S. olivacea has setae number of 4,4 combination on both sides of the basal segment of antenna. It is different from three other species which are either ¡§ 3,3¡¨ or ¡§ 3,4¡¨ or ¡§ 4,3¡¨ combination. S. tranquebarica has setae number of 4,5 combination on the last two segments of antennule. It is different from three other species, which have 3,3 combination. In addition, these four kinds of megalopa are different on the fifth pleopod, third maxilliped and fifth pereiopod. Furthermore, megalopa of four Scylla species have significant differences in their shape and size. For example, S. olivacea is the largest one in both rostral width and carapace length, followed by S. serrata, S. paramamosain, and S. tranquebarica is the smallest one. In the first crab, as adult, significant differences are found on the frontal median spines and chelipeds. From September 1999 to September 2000, megalopae of four Scylla species were collected from the coast and offshore of Linpien and Fanzilum. Large amount of megalopa can be identified in to species using of one-step multiplex PCR. Results showed that S. paramamosain is the most abundant (67.7¡Ó21.5%) , followed by S. serrata (19.3¡Ó15.5%), S. olivacea (12.3¡Ó11.9%), and S. tranquebarica (0.7¡Ó1.7%) is the least one. Most of the megalopa (77.1%) molted during the night. The megalopa caught from coast took one day (p<0.001) less to become the first crab than those caught from offshore. S. paramamosain took one day more than S. serrata and S. olivacea.Salinity doesn¡¦t affect the time of molt.

Induced molting is process used by commercial producers to extend the reproductive life of a laying hen. Typically, producers deprive hens of feed for a period of 7-14 days while reducing the amount of light exposure to the hens. This allows for regression of the reproductive tract and for a second cycle of egg production to occur. However, induced molting by feed deprivation has been shown to increase the hen's risk of becoming infected with pathogenic bacteria, such as Salmonella. This increased risk could mean an increase in contaminated eggs or egg products, which causes concerns for public health. This combined with increasing pressure on egg producers from animal welfare organizations has prompted the investigation of diets that would provide available energy for the hens, while still inducing a molt that is economically advantageous to producers. Alfalfa, provided in meal or pelleted form, provides only 1/2 the metabolizable energy and 1/4 of the calcium required of a laying hen that is reproductively active. Due to the decrease in nutrients, alfalfa was investigated as an alternative to feed deprivation. Studies were conducted to assess egg quality, egg production, consumer acceptance, and hen physiology.

Induced molting is process used by commercial producers to extend the reproductive life of a laying hen. Typically, producers deprive hens of feed for a period of 7-14 days while reducing the amount of light exposure to the hens. This allows for regression of the reproductive tract and for a second cycle of egg production to occur. However, induced molting by feed deprivation has been shown to increase the hen's risk of becoming infected with pathogenic bacteria, such as Salmonella. This increased risk could mean an increase in contaminated eggs or egg products, which causes concerns for public health. This combined with increasing pressure on egg producers from animal welfare organizations has prompted the investigation of diets that would provide available energy for the hens, while still inducing a molt that is economically advantageous to producers. Alfalfa, provided in meal or pelleted form, provides only 1/2 the metabolizable energy and 1/4 of the calcium required of a laying hen that is reproductively active. Due to the decrease in nutrients, alfalfa was investigated as an alternative to feed deprivation. Studies were conducted to assess egg quality, egg production, consumer acceptance, and hen physiology.

There is increasing interest in developing methods to detect and identify Salmonella, to eliminate or reduce the risk of contamination of shell eggs, and to retain the economic advantages of induced molting without increasing the risk of Salmonella enteritidis infection. S. enteritidis and S. typhimurium are the most common serotypes among 2449 known serotypes of the Salmonella, and are the causes of most egg- related foodborne salmonellosis in humans in the U. S. These two species are also responsible for environmental contamination and the incidence of infections. Therefore, this study was conducted in three phases consisting of ten in vivo and in vitro experiments. This study investigated the effects of zinc on Salmonella growth and survivability in poultry environments, and its ability to induce a molt in single comb white leghorn hens. In part, the antibacterial properties of zinc may reduce environmental contamination in a poultry house by interrupting airborne routes. The first phase involved detecting airborne bacteria by aerosol sampling methods, and then screening any Salmonella mutant (s) that survived desiccation by transposon footprinting. The second phase examined, in vitro, the addition of zinc on the growth kinetics of Salmonella under aerobic or anaerobic conditions, the effects of combinating zinc and acidic conditions on the growth kinetics of Salmonella in vitro under aerobic or anaerobic conditions, and the effects of zinc amended feed on the survival of a dry inoculum of Salmonella. The third phase investigated the ability of zinc propionate, as an alternative salt form of zinc, to induce molt in laying hens, the influence of zinc acetate and zinc propionate on gastrointestinal tract fermentation, and susceptibility of laying hens to S. enteritidis during an induced molt, and the comparison of digestive microbial crop and cecal communities among molted hens fed by either zinc acetate or zinc propionate amended molting diets with hens undergoing feed withdrawal or full fed nonmolted hens using molecular-based denaturing gradient gel electrophoresis.

The linking of breeding and nonbreeding grounds of migratory birds is of great conservation and theoretical importance. In theory, connecting these geographically disparate areas allows for a more complete understanding of annual events, and a first step into identifying where in the annual cycle limitations to fitness may be occurring. <p>The Loggerhead Shrike (<i>Lanius ludovicianus</i>) is a Species at Risk in Canada, and its decline is attributed to habitat loss on both the breeding and wintering grounds. In the fall, Loggerhead Shrikes from breeding areas of prairie Canada (<i>L. l. excubitorides</i>), the focus of this study, move south along the Gulf States of the United States and Mexico to wintering areas that are already occupied year-round by resident shrikes. However, the habitat structure and variability for both migrants and resident Loggerhead Shrikes have not been studied well on the wintering grounds. Thus, it has been difficult to adequately evaluate the relative contribution of changes in wintering areas to the decline of Loggerhead Shrike populations. To identify the wintering grounds of Loggerhead Shrikes that breed in prairie Canada, I used stable hydrogen isotope (δD) analysis of feathers and claws and microsatellite DNA from feathers. In North America, δD measurements from feathers provide information on latitude of origin, while DNA can be related to an affiliation to a breeding population. Since several authors suggested that Loggerhead Shrike completed their preformative and formative molt on the breeding grounds prior to fall migrations, I reasoned that δD analysis of tertial feathers sampled on the wintering grounds would correspond to δD in precipitation from the breeding grounds. Similarly, I used DNA microsatellite markers and Bayesian clustering analysis to detect patterns of population genetic structure within the range of Western Loggerhead Shrikes (<i>L. l. excubitorides</i>) in Canada and consequently use these to infer breeding origin of shrikes sampled in Mexico. I based the categorization of resident and migrant Loggerhead Shrikes sampled in Mexico on δD analysis of feathers. Based on evaluation of observed and expected δD values of feathers, I determined that migrant shrikes used northeastern (63.8%) and south-central (73.7%) Mexico to winter. Microsatellite DNA and assignment tests, suggested that wintering migrant shrikes occupied north-central (18.6%) and northeastern (20.3%) Mexico. Differential habitat occupancy analyses, suggested that, in northeastern Mexico, wintering sites occupied by Loggerhead Shrike sites were structurally different from random unoccupied sites (MRPP, T = -8.04, P < 0.001, n = 354). An important difference was that, on average, occupied habitat contained shorter tall shrubs and huisache and fewer tall shrubs, mesquite and huisache. Similarly, residents shrikes occupied structurally different habitats (MRPP, T = -2.95, P = 0.01, n = 146) that had less percent cover of bare ground than those sites occupied by migrants. Based on these habitat results, I surmise that habitat availability may be a limiting factor for both resident and migratory shrike populations in northeastern Mexico.

The linking of breeding and nonbreeding grounds of migratory birds is of great conservation and theoretical importance. In theory, connecting these geographically disparate areas allows for a more complete understanding of annual events, and a first step into identifying where in the annual cycle limitations to fitness may be occurring. <p>The Loggerhead Shrike (<i>Lanius ludovicianus</i>) is a Species at Risk in Canada, and its decline is attributed to habitat loss on both the breeding and wintering grounds. In the fall, Loggerhead Shrikes from breeding areas of prairie Canada (<i>L. l. excubitorides</i>), the focus of this study, move south along the Gulf States of the United States and Mexico to wintering areas that are already occupied year-round by resident shrikes. However, the habitat structure and variability for both migrants and resident Loggerhead Shrikes have not been studied well on the wintering grounds. Thus, it has been difficult to adequately evaluate the relative contribution of changes in wintering areas to the decline of Loggerhead Shrike populations. To identify the wintering grounds of Loggerhead Shrikes that breed in prairie Canada, I used stable hydrogen isotope (δD) analysis of feathers and claws and microsatellite DNA from feathers. In North America, δD measurements from feathers provide information on latitude of origin, while DNA can be related to an affiliation to a breeding population. Since several authors suggested that Loggerhead Shrike completed their preformative and formative molt on the breeding grounds prior to fall migrations, I reasoned that δD analysis of tertial feathers sampled on the wintering grounds would correspond to δD in precipitation from the breeding grounds. Similarly, I used DNA microsatellite markers and Bayesian clustering analysis to detect patterns of population genetic structure within the range of Western Loggerhead Shrikes (<i>L. l. excubitorides</i>) in Canada and consequently use these to infer breeding origin of shrikes sampled in Mexico. I based the categorization of resident and migrant Loggerhead Shrikes sampled in Mexico on δD analysis of feathers. Based on evaluation of observed and expected δD values of feathers, I determined that migrant shrikes used northeastern (63.8%) and south-central (73.7%) Mexico to winter. Microsatellite DNA and assignment tests, suggested that wintering migrant shrikes occupied north-central (18.6%) and northeastern (20.3%) Mexico. Differential habitat occupancy analyses, suggested that, in northeastern Mexico, wintering sites occupied by Loggerhead Shrike sites were structurally different from random unoccupied sites (MRPP, T = -8.04, P < 0.001, n = 354). An important difference was that, on average, occupied habitat contained shorter tall shrubs and huisache and fewer tall shrubs, mesquite and huisache. Similarly, residents shrikes occupied structurally different habitats (MRPP, T = -2.95, P = 0.01, n = 146) that had less percent cover of bare ground than those sites occupied by migrants. Based on these habitat results, I surmise that habitat availability may be a limiting factor for both resident and migratory shrike populations in northeastern Mexico.

Molting is a natural occurrence in the Avian species that can include a period of fasting. Animal rights groups view the longepted standard industry practice as inhumane. Based on influences from these groups and the recommendation of its scientific committee, United Egg Producers (UEP) requires members of its Animal Care Certified Program use a noneed withdrawal molting program, even though the morphological and physiological effects of this method have not been studied in depth and the existing literature provides contradictory results. Research regarding how to induce a noneed withdrawal molt has been performed using feed that is nutrient deficient or contains an additive to cease egg production. Studies have shown subsequent egg production to be comparable to hens molted using feed withdrawal. This study was designed to determine the morphological and physiological changes that occur in a noneed withdrawal molt. Two hundred hens divided into 40 groups of 3 birds each were molted in a staggered pattern so that the morphological and physiological effects of noneed withdrawal molt could be measured with identical environmental and housing variables. Data was divided into 5 sections including Control (n=5), Start (n=7), Mid-Molt (n-7), Near End (n=7), and Over (n=15). Internal organs were examined and measured. Corticosterone levels were measured to determine if noneed withdrawal molting causes less stress to hens. Pertinent blood parameters including cholesterol, glucose, O2, CO2, hemoglobin, and hematocrit were also measured. Results indicate internal organ weight changes due to noneed withdrawal molt were as expected. Decreases in the oviduct length, ovary weight, follicle weight, and follicle number indicate regression of the reproductive tract. No differences (P<0.05) were observed in corticosterone levels, suggesting that a noneed withdrawal molt does not increase stress in laying hens.

L'agressivité est un comportement fréquemment observé chez les animaux et qui est notamment modulé par la sérotonine (5-HT) et les hormones stéroïdes. Cependant, même si des hypothèses évoquent une interaction possible entre ces molécules dans la régulation des comportements agressifs, peu d’études permettent de les confirmer. De plus les mécanismes neuronaux sous-tendant ces comportements agressifs sont encore peu connus. En utilisant comme modèle l'écrevisse de Louisiane, très étudiée pour son comportement agressif et ses hiérarchies sociales, ce travail montre comment la 5-HT et les hormones stéroïdes modifient les réseaux neuronaux et contrôlent ainsi l'agressivité de ces animaux. La mue des écrevisses est contrôlée par une hormone stéroïde appelée 20-hydroxyecdysone (20E), dont la concentration augmente pendant la prémue. Durant cette période, la 20E diminue à la fois l’agressivité des écrevisses et la locomotion. L’activité du réseau locomoteur, un des supports essentiels de l'agressivité (permettant les approches, les attaques… ou les fuites) et son intégration sensori-motrice sont fortement inhibés également. Cette inhibition passe par une réduction de la réactivité des réseaux, notamment via la baisse de résistance d’entrée (Rin) des motoneurones. En présence de 20E, la concentration de 5-HT augmente fortement dans l’organisme par l’inhibition présumée de la voie de dégradation de la 5-HT. Nous supposons comme déjà décrit sur d’autres réseaux que cette augmentation bloquerait les réseaux dans un état inhibée. Cet état inhibée serait maintenu par la baisse de Rin, causée par la libération de 5-HT sur la partie périphérique des MN principalement inhibitrice. / In animal kingdom, aggressivity is a very frequent behavior obvious. Serotonin (5-HT) and steroid hormones modulate this behavior. However, even if several hypothesis raise that one interaction is possible between these molecules to control aggressivity, no study can confirm it. Moreover, neuronal actions behind this behavior stay unclear. In this study, we show how 5-HT and steroid hormones can regulate neural networks and aggressivity. Crayfish molting is regulated by a steroid hormone, called 20-hydroxyecdysone (20E) and its concentration increases during pre-molt period. 20E decreases crayfish aggressivity and locomotion. Locomotors activities and sensory-motor integration are also inhibited during pre-molt. This inhibition is caused by a drop of neural reactivity because input resistance of motoneurons decreases. After injection of 20E or during pre-molt period, 5-HT concentration increase. We think this increase would block networks in inhibition state during pre-molt.

Four experiments were conducted to evaluate guar meal as a source of prebiotic galactomannans for laying hens. In the 1st experiment, late phase laying hens were fed diets with 0, 5, 10% guar meal (GM) for 56 days or 15% GM for 28 days then switched to the 0% GM diet for the final 28 days. In the 2nd experiment, young pullets were fed guar germ (GG) or GM at 0, 2.5 or 5% for 20 weeks. In the 1st and 2nd experiments, egg production and feed consumption were not affected by feeding up to 5% guar by-products whereas feed efficiency was decreased by guar feeding. Feeding of GG or GM did not affect egg weight or shell quality, but decreased the egg yolk color and Haugh units. Guar increased absolute and relative liver weight, but did not affect the weights of the pancreas, spleen, or the incidence of fatty liver or liver hemorrhage. Feeding 10% GM depressed feed consumption and increased body weight loss. Feeding 15% GM severely depressed egg production followed by a recovery of production after returning to 0% GM feeding. In the 3rd and 4th experiments, late phase laying hens were induced to molt by feed withdrawal (FW) or feeding 15 or 20% GM with or without β-mannanase (Hemicell??). All hens except those fed 15% GM with enzyme obtained a complete cessation of lay in 10 days. Compared to FW birds, hens fed GM had lower body weight reduction and mortality, while hens fed 20% GM with enzyme had higher post-molt egg production. Salmonella enteritidis (SE) present in 6 organs (crop, liver, spleen, ovary, oviduct and cecum), and SE in cecal contents were significantly reduced by 20% GM feeding with and without enzyme. The results showed that GG or GM can be safely fed to laying hens up to 5% without adverse effects on performance. An alternative molting method employing 20% GM with or without β-mannanase is preferable to FW because GM feeding results in a complete molt and decreases mortality, as well as enhances the resistance to SE of molted hens.

Four experiments were conducted to evaluate guar meal as a source of prebiotic galactomannans for laying hens. In the 1st experiment, late phase laying hens were fed diets with 0, 5, 10% guar meal (GM) for 56 days or 15% GM for 28 days then switched to the 0% GM diet for the final 28 days. In the 2nd experiment, young pullets were fed guar germ (GG) or GM at 0, 2.5 or 5% for 20 weeks. In the 1st and 2nd experiments, egg production and feed consumption were not affected by feeding up to 5% guar by-products whereas feed efficiency was decreased by guar feeding. Feeding of GG or GM did not affect egg weight or shell quality, but decreased the egg yolk color and Haugh units. Guar increased absolute and relative liver weight, but did not affect the weights of the pancreas, spleen, or the incidence of fatty liver or liver hemorrhage. Feeding 10% GM depressed feed consumption and increased body weight loss. Feeding 15% GM severely depressed egg production followed by a recovery of production after returning to 0% GM feeding. In the 3rd and 4th experiments, late phase laying hens were induced to molt by feed withdrawal (FW) or feeding 15 or 20% GM with or without &#946;-mannanase (Hemicell??). All hens except those fed 15% GM with enzyme obtained a complete cessation of lay in 10 days. Compared to FW birds, hens fed GM had lower body weight reduction and mortality, while hens fed 20% GM with enzyme had higher post-molt egg production. Salmonella enteritidis (SE) present in 6 organs (crop, liver, spleen, ovary, oviduct and cecum), and SE in cecal contents were significantly reduced by 20% GM feeding with and without enzyme. The results showed that GG or GM can be safely fed to laying hens up to 5% without adverse effects on performance. An alternative molting method employing 20% GM with or without &#946;-mannanase is preferable to FW because GM feeding results in a complete molt and decreases mortality, as well as enhances the resistance to SE of molted hens.