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71.
Herbert E. Quintero Alison Hutson Atra Chaimongkol Allen Davis Rex Dunham Asheber Abebe 《Journal of the World Aquaculture Society》2009,40(5):601-615
The interspecific hybridization of channel catfish, Ictalurus punctatus, females with blue catfish, I. furcatus, males has been identified as a method to further improve production; however, lack of spawning success has affected its commercial application. To facilitate our understanding of the interaction of brood stock nutrition and reproductive performance, we evaluated the interaction of feed quality and feeding frequency. Channel catfish females were classified into two genetic groups, namely, high and low spawning. The treatments were offered during the spring season 70–90 d prior to the start of the spawning season. Induced reproduction was performed using luteinizing hormone releasing hormone analog. Condition of the fish as well as reproductive performance using spawning success, egg production, egg size, and fertilization at 48 h were determined. Changing protein level of the diet from 32 to 42% did not influence spawning, fecundity, or fertilization, but affected egg size and biochemical composition of the eggs. Increasing the feeding frequency from three to six times per week negatively affected spawning in one of the two genetics groups, did not affect egg production and egg fertilization, but had a significant effect on egg size. Older fish performed better than younger fish in terms of spawning success and egg production. 相似文献
72.
There is considerable interest in the culture of whiteleg shrimp (Litopenaeus vannamei) in inland low‐salinity water in Alabama and other states in the Sunbelt region of the US. However, the growing season is truncated as compared with tropical or subtropical areas where this species is typically cultured, and temperature is thought to be a major factor influencing shrimp production in the US. This study, conducted at Greene Prairie Aquafarm located in west‐central Alabama, considered water temperature patterns on a shrimp farm in different ponds and different years; and sought possible effects of bottom water temperature in ponds on variation in shrimp survival, growth and production. Water temperature at 1.2 m depth in 22 ponds and air temperature were monitored at 1‐hr intervals during the 2012, 2013, 2014 and 2015 growing seasons. Records of stocking rates, survival rates and production were provided by the farm owner. Correlation analysis and linear mixed model analysis of variance were used. Results showed that hourly water temperatures differed among ponds. The range of water temperature in each pond explained 41% of the variance in average final weight of shrimp harvested from each pond. In conclusion, the results suggest that variation in water temperature patterns has considerable influence on shrimp growth and survival in ponds. 相似文献
73.
74.
A key assumption in many homegarden studies is that homegardens are ecologically and socio-economically sustainable due to
their species diversity. The precise relation between diversity and sustainability is still heavily debated, however. A basic
question is how diversity in homegardens can best be characterized in view of the various dimensions of species diversity
and their variation in time and space. This paper assesses different types of species diversity in the homegardens of Sidama
region of southern Ethiopia. In a survey of crop species in 144 homegardens a total of 78 cultivated crop species (excluding
trees) belonging to 10 functional groups were recorded; there were on average 16 crop species and 8 functional groups per
farm. Within homegardens, plots differ in species composition and crop diversity. Four types of homegarden systems are distinguished
differing in both type and area-share of dominant species, relative orientation at subsistence or cash production and overall
crop diversity. The gradual replacement of enset by maize and of coffee by more financially attractive cash crops khat and
pineapple causes a decrease in overall crop diversity. Our data demonstrate that it is incorrect to consider homegardens as
generic systems with a uniform distribution of species diversity: important within and between homegarden variation exists.
Ecological and socio-economic sustainability is not just related to species diversity per se, but rather to more specific
features such as presence of keystone species and diversity in functional species groups. Socio-economic sustainability in
terms of adjustment to socio-economic change implies dynamics in species diversity. 相似文献
75.
Survey of ixodid ticks in domestic ruminants in Bedelle district,Southwestern Ethiopia 总被引:1,自引:1,他引:0
Mesele Abera Tirazu Mohammed Rahmeto Abebe Kassaye Aragaw Jemere Bekele 《Tropical animal health and production》2010,42(8):1677-1683
A survey aimed at determining the status of ticks in cattle, sheep and goats in Bedelle district (Southwestern Ethiopia) was
carried out from November 2007 to April 2008. Out of the total 330 animals examined, 314 (95.2%) were found to be infested
(harbouring of at least a single tick). High rates of infestations were recorded across all three host species. Factors like
month of collection, age and sex of host species did not show significant association with infestation rates. A total of 5,507
ticks belonging to three genera (i.e. Amblyomma, Boophilus and Rhipicephalus) were collected during the study period of which six species were identified. The species of ticks encountered comprise of
Amblyomma cohaerens (44.1%), Amblyomma variegatum (13.8%), Amblyomma lepidum (1.2%), Boophilus decoloratus (24.9%), Rhipicephalus evertsi evertsi (14.3%) and Rhipicephalus lunulatus (1.7%). As about 86.7% (4,772) of the ticks were collected from cattle, it was recognised that this could be an evidence
of host preference where cattle are serving as principal host while sheep and goats serve as alternative hosts. The role of
ecological factors and little attention paid by livestock owners for treatment of animals against ticks are suggested to result
in the abundance of ticks. Acaricide spraying should be strategically applied to control ticks. Better result could be achieved
if an emphasis is being put on spraying cattle. Studies on tick-borne diseases, involvement of wildlife species as well as
related factors are recommended as they may provide a valuable basis for designing and launching an all-round control programme
in the country. 相似文献
76.
1. A chick experiment was designed to test whether the proven effect of excess protein on the requirement for lysine was associated with the arginine content of the protein. 2. Protein contents of 180, 220, 260 and 300 g/kg diet were fed in combination with lysine concentrations of 38, 43, 48, 53 and 58 g/kg crude protein and arginine concentrations of 49.4 or 68.4 g/kg crude protein. 3. Growth rate and efficiency of food utilisation were not significantly affected by the arginine content of the protein. Significant responses to lysine were obtained at all protein contents. 4. Lysine required for maximum growth or maximum food efficiency increased in direct proportion to the protein content of the diet and was not affected by arginine content of the diet within the range of concentrations tested. 相似文献
77.
1. Chicks were fed from 4 to 18 d on 40 diets containing all combinations of 8 crude protein (CP) concentrations (from 160 to 300 g/kg) and 5 tryptophan concentrations (from 7.5 to 13.5 g tryptophan/kg CP). 2. At each protein concentration there were responses in growth rate and in efficiency of food utilisation to supplementation with tryptophan. Curves were fitted to estimate the maximum response at each protein concentration. 3. The amounts of tryptophan required (g/kg) for maximum growth and maximum food efficiency were each linear functions of dietary protein concentration. The chick's requirement for tryptophan can be expressed as 12 g/kg CP. 4. It is concluded that a fixed ratio of tryptophan to protein should be specified in practical diet formulation, rather than a minimum dietary concentration of tryptophan. 相似文献
78.
Getachew Tesfaye Abebe Ayele Gizaw Solomon Rischkowsky Barbara Bisrat Asfaw Haile Aynalem 《Tropical animal health and production》2020,52(6):2977-2985
Tropical Animal Health and Production - In the traditional Menz sheep breeding, communities select against black coat color and therefore its frequency is declining over time. We hypothesize that... 相似文献
79.
Broodstock evaluations are often measured by variables such as spawning success, fecundity, fertilization and hatching rates, usually expressed as percentage values. Outcomes are generally analysed as continuous random variables, assuming that they follow a normal distribution. Ordinary linear regression models (e.g. analysis of variance) as well as χ2 analysis are typically applied. However, these models may not be the most appropriate as a number of test criteria may not be met. For example, spawning success outcomes are inherently discrete and non‐negative data and hence their distribution is not likely to be normal. As these models may not be the most appropriate, a case study using logit analysis as an alternative method for the evaluation of this type of data is presented by considering the response as binary data (spawned versus did not spawn). An exact version of logit analysis was performed due to the sparseness of the data. The results demonstrate that appropriate statistical models provide better insight into the cause–effect relationships that exist between control variables and the dependent variable (likelihood of spawning in this case). As would be expected, each strain of fish responded somewhat differently to the test variables. Changing the protein level of the diet from 32% to 42% or increasing the feeding frequency from three to six times per week either did not influence spawning or negatively affected spawning respectively. Additionally, older fish performed better than younger fish and the early spawning period was better than the later spawning period, regardless of strain. These responses, however, were only detected using logit analysis, which is a more sensitive test and would thus be recommended for this type of data. 相似文献
80.
Stagnant early growth and mortality are the major impediments for sheep production in southern Ethiopia. We evaluated the effects of non-genetic factors on early growth performance of lambs in Halaba district with 467 lambs owned by 60 households. Body weights (kilograms) of lambs at birth, 30, 60, 90, 120, and 150 days were 2.30 ± 0.03, 4.45 ± 0.11, 6.94 ± 0.13, 10.4 ± 0.19, 13.3 ± 0.19, and 15.7 ± 0.20, respectively. The average daily gain (ADG; gram) from birth to 30, 60, 90, 120, and 150 days were 71.18 ± 8.18, 77.18 ± 2.19, 89.20 ± 1.98, 91.18 ± 1.51, and 90.68 ± 1.27, respectively. Season effect was significant (p < 0.05) for weight at birth, 30, and 120 days. Similarly, season of birth influenced (p < 0.05) ADG (gram) at all ages except from birth to 60 days. Single-born lambs were heavier over multiple births (p < 0.01), 90 (p < 0.001) and 120 days (p < 0.05) and higher (p < 0.001) ADG from birth to 90 days. There were significant interaction effects of parity by sex at birth (p < 0.01) and parity by type of birth (p < 0.001) and 90 days (p < 0.01). From the non-genetic factors estimated in this study, season and type of birth, and their interaction had a more profound effect at early growth of lambs, and they need to be considered in the improvement plan of sheep under Halaba arid to semi-arid environments. Efforts geared towards planned breeding, improved nutrition, and health would assist farmers to exploit these indigenous and adaptable sheep resources efficiently. 相似文献