In this paper the major description, epidemiology, pathogenesis and clinical sign, diagnosis, treatment and control of parasitic crustaceans in fish has been reviewed. The major crustaceans parasites commonly encountered in cultured and wild fish are: copepods (ergasilidea and lernaeidae), branchiura (argulidae) and isopods). Members of the branchiura and isopod are relatively large and both sexes are parasitic, while copepods are the most common crustacean parasites are generally small to microscopic with both free-living and parasitic stages in their life cycle. These parasitic crustaceans are numerous and have worldwide distribution in fresh, brackish and salt water. Most of them can be seen with naked eyes as they attach to the gills, bodies and fins of the host. They are increasingly serious problem in cultured fish and can infect wild population. Usually they cause only minor harm to their hosts when present in small numbers. However, in case of heavy infections severe damage to skin, muscles, and gills tissue accompanied with secondary infections, and resulting in decreased production. Good health management and good environment management are crucial in avoiding occurrence of crustacean parasites.
An exploratory field survey was conducted in north Gondar zone, Ethiopia to identify and characterize the local chicken ecotypes. Seven qualitative and twelve quantitative traits from 450 chickens were considered. Chicken ecotypes such as necked neck, Gasgie and Gugut from Quara, Alefa and Tache Armacheho districts were identified, respectively. Morphometric measurements indicated that the body weight and body length of necked neck and Gasgie ecotypes were significantly (p < 0.01) higher than Gugut ecotypes except in shank circumstances. Sex and ecotype were the significant (p < 0.01) sources of variation for both body weights and linear body measurements. The relationship of body weight with other body measurements for all ecotypes in both sexes were highly significant (r = 0.67, p < 0.01). Some traits like wingspan, body length and super length (r = 0.64, P < 0.01) for males and for females (r = 0.59, P < 0.01) of necked neck chickens are significantly correlated with body weight. Therefore, highly correlated traits are the basic indicators for estimation of the continuous prediction of body weight of chicken. Identification and characterization of new genetic resources should be employed routinely to validate and investigate the resources in the country.
The dairy industry faces a unique challenge to constantly improve functionality of the dairy cows to meet the needs of future production and reproduction demands. The basis of improvements is selection of the best animals. The accuracy of selection can be increased by using the combined analysis of both direct information on herd life and indirect information obtained from conformation traits. Generally, conformation traits are important in dairy cattle development. These traits are used for selection of animals through creating the predict equation based on the independent variable and assuring selection of the superior animal with its important trait. The functional conformation traits that influence or facilitate the longevity and reproduction status of dairy cows are the appearance of udder conformation, feet and leg conformation, thoracic and abdominal body conformation, and rump and loin structure. The relationship between conformation traits with milk production and reproduction traits might be different among breeds, which could have implications for the use of conformation traits in different dairy cattle breeding programmes. The estimated correlations between longevity and different conformation traits are also varying with breeds.
During the subsequent history of livestock, the main evolutionary forces of mutation, selective breeding, adaptation, isolation and genetic drift have created an enormous diversity of local populations. This farm animal genetic diversity has a primary requirement to meet current production needs in various environments. In addition, farm animal genetic diversity has a great application of allowing sustained genetic improvement and to facilitate rapid adaptation to changing breeding objectives. Furthermore, animal genetic diversity provides wider range opportunity for selection and improving. The nondescript breed could be identified and characterizing by morphological or/and molecular markers to know their potential, their special adaptive trait and their status for further actions (improvement, conservation). Markers are conspicuous object used to distinguish or to show variation in population or individual level. Morphological markers normally refer to external animal characteristics which can be obtained by direct visual observation and measurement and used in the identification, classification and characterization of genetic evolution of different species or populations. Since the measurement and identification of animal morphological traits usually take a long time and limited application in evaluation of qualitative traits, molecular markers have developed quickly and they are becoming more and more informed. Whatever data type (morphological and molecular data) needs appropriate statistical application. In general, diversity, markers and statistical application were the preliminary tools of breed characterization and breed improvements.
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