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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The acute radiation syndrome in large domestic animals, with special reference to X-irradiation in goats

Wilkins, J. H. January 1965 (has links)
No description available.
2

Perinatal studies in Equidae with special reference to passive transfer of immunity

Jeffcott, L. B. January 1972 (has links)
This work represents a study of aspects of passive immunityand the method of its transmission to the Dewly born foal. All the foals examined were agammaglobulinaemicat birth. Traces of antitoxin, too low to be of any protective value, were present in foals born to hyper immune dams. The foals rapidly acquired passive y globulbin by absorption of colostral proteins from the small intestine. The antibody levels attained were somewhatlower than those of the dams' serum at parturition. The passive y globulin and anti toxin declined steadily after 24 hours and br three weeks at age their levels bad been halved. The duration of demonstreble passive immunity did not extend for more than four months of life. The development of active immunity began within the first month of life. Autogenous y globulin was detected after two weeks in the colostrum deprived foals. In foals which received colostrum, y globulin levels approaohing those for adult horses were detected by about four months of age. The mechanism of absorption of colostral proteins was by uptake into the epithelial cells of the small intestine and transfer via the lacteals to the systemic oirculation. The intestine was apparently non-selective in its absorption of maoromolecules. The efficiency of absorption three hours after birth of labelled PVP, a synthetic polymer of similar molecular size to y globulin, was shown to be 22% of the total dose. There followed a linear decline in efficiency of absorption with age to the lowest recorded levels at 20 hours. By 24 hours of life the intestinal epithelium was no longer permeable to marker antibody. Examination of the colostral proteins after absorption revealed that the high molecular weight component, y globulin, was retained in the foal's circulation, but that the smaller size milk proteins were excreted in the urine. This neonatal proteinuria persisted only during the period of intestinal absorption.
3

Genetic and development analysis of the n-type strains of the Romney Marsh breed of sheep

Fraser, A. S. January 1951 (has links)
No description available.
4

A study of the skeletal muscles of sheep, with special reference to scrapie disease

Hulland, T. J. January 1959 (has links)
No description available.
5

The effect of sex condition, growth rate and slaughter weight on live and carcass characteristics of Welsh mountain lambs

Kirk, John A. January 1980 (has links)
A series of experiments were conducted to ascertain the effects of sex conditions, slaughter weight, environment and sire performance on the growth and carcass composition of Welsh Mountain lambs. Entire lambs reached target slaughter weight 28.5 days earlier than castrates. Killing our percentage was higher in castrates regardless of rearing environment and they yielded significantly greater carcass weights than entires. Estimated lean and fat percentages showed entire animals to have greater lean and less fat than castrates. Increases in slaughter weight resulted in significant increases in fat percentage with a corresponding decrease in lean percentage. Progeny testing of high and low performance tested rams was carried out to assess their influence on liveweight growth and carcass composition of entire Welsh Mountain lambs. Ram lambs were reared on the ffridd. High progeny reached slaughter weight on average 30 days earlier than the progeny of low rams. Killing out percentage and cold carcass weights were significantly higher in low performance progeny. However, high progeny had significantly greater lean and less fat percentage in their carcasses. Ewe lambs reared on the open mountain also showed that progeny of high rams grew at a faster rate than progeny sired by low rams. When ram lambs were individually penned indoors it was found that the progeny of high sires had greater liveweight gain than low progeny whilst feed intake was similar for both groups, as a result feed conversion efficiency was better in progeny of high performance rams. Wool samples taken from ewe lambs were compared but no consistent differences could be detected in any wool characteristics. The results suggest that Welsh Mountain lambs if reared as entires could be taken to heavier slaughter weights than is normal, with no adverse effect on carcass composition. Progeny sired by rams who perform well on performance test grew faster and at the same slaughter weights produce leaner carcasses than progeny sired by low performance sires.
6

Studies on ephedrine metabolism in ponies

Nicholson, J. D. January 1971 (has links)
No description available.
7

Suitability of selected raw materials and by-products in formulated feeds for Nile tilapia Oreochromis niloticus and African catfish Clarias gariepinus

Abdel-Warith, Abdel-Wahab A. January 2002 (has links)
The current status of global aquaculture production was reviewed with a special emphasis on Africa and in particular Egypt. The main species of interest in this study were tilapia Oreochromis niloticus and African catfish Clarias gariepinus which are gaining popularity and are of considerable importance in the market of farmed fish in this continent and of economic relevance to Egypt and other Middle Eastern countries. Research was principally directed to establishing the suitability of specific feed ingredients and materials that could be included in balanced diets for both species. Various animal and plant by-products were selected to evaluate their nutritional value for either species. The experimental protocols, materials and methods and techniques employed are described for nutritional investigations with tropical freshwater fish. These included the various parameters assessed in the growth and digestibility studies relevant to the species in question. These include Specific Growth Rates (SGR), Feed Conversion Ratios (FCR), Protein Efficiency Ratio (PER) and Apparent Net Protein Utilisation (ANPU). An initial investigation to determine the coefficients of digestibility of protein, amino acids and energy was first undertaken using tilapia as the model warmwater fish species. This investigation was able to provide useful data and information as a prelude for successive growth trials with both tilapia and catfish. Fishmeal, soyabean meal, corn gluten meal, poultry by-products including feathermeal and blood meal were all tested at a variety of inclusion levels in successive trials. Apparent digestibility coefficients (ADC %) for tilapia fed diets containing 60% LT 94 fishmeal and 40% of each ingredient are reported. ADC of dry matter (DM) and protein (CP) and energy (E) for the reference fishmeal diet were 83.99 DM; 92.60 CP; and 93.31E respectively. For each test ingredient, these values were as follows; 1- PBM (56.99 DM; 69.30 CP & 73.47 E), 2- Feathermeal (54.09 DM, 45.53 CP & 49.11 E), 3- Blood meal (76.13 DM; 85.79 CP and 75.96 E), 4- Solvent extracted soyabean meal (85.83 DM; 93.46 CP & 82.16 E), 4- Full fat soyabean meal (75.86 DM; 86.99 CP & 74.84 E). The amino acid availability coefficients reflected the same trends as protein digestibility, and these varied from >87% on average for the essential amino acids in fishmeal, 83% for maize gluten and 85% for solvent extracted soyabean meal with an average of 63% for feathermeal and only 61% for poultry meat meal. The importance of plant protein sources and especially soyabean meal was the focus of a complete nutritional study with juvenile tilapia, The influence of full fat soyabean meal (FFSB) inclusion on growth performance, feed utilisation and the gastrointestinal digestive enzymes was also measured in this experiment. It was found that soyabean meal levels above 50% could reduce growth performance and adversely affect gut enzyme activities. Tilapia fed a series of diets with FFSB (58,63 and 63% + DLmethionine did not perform as well as the control group. SGR values ranged between 2.42 to 2.12, and ANPU between 39.41-34.46. Supplementation of the diet with methionine did not restore performance. Hepatic trypsin and amylase enzyme activity was affected with FFSB (from 12.64-1.43 Units and 4.99-2.76 Units respectively). No affects were detected on general proteolytic activity for stomach, intestine and liver. For studies with African catfish, it was first necessary to assess the different grades of fishmeal that could be employed in suitable reference diets for this species. A Poultry by-product meal (PBM) was further evaluated as a fishmeal replacement source (0- 100%) for this species. Catfish fed dry and wet diets of two types of fishmeal showed significant differences in growth performance. Catfish fed dry diets performed better than those receiving wet diets for both LT94 and white fishmeal sources. SGR were (2.80 and 2.75 dry) and (2.46 and 2.57 wet). FCR (0.97 and 0.80 dry) and (1.30,1.30 wet), ANPU (41.85,52.94 dry) and (31.43,30.9 wet) for LT94 and White fishmeal respectively. The PBM fed catfish showed significant differences in weight gain and feed utilisation. SGR was between 3.57 to 2.83, FCR between 1.61 to 2.25 and ANPU fell from 28.90 to 18.82 for groups' fed the control fishmeal diet towards the maximum level of PBM substitution. Histological examination of liver tissue showed alterations in hepatic morphology with respect to sinusoids and fat accumulation for catfish fed higher amounts of PBM. A restricted inclusion of up to 40% poultry by-product meal could therefore be suggested for practical diet formulations. Further investigations were undertaken to assess the potential for either maize gluten meal (MG) or soyabean meal as substitute protein sources for the African catfish Catfish fed higher inclusions of MG displayed SGR's ranging between 5.28 to 2.79, FCR between 0.81 to 1.53 and ANPU values from 52.33 to 24.99%. All lower performance data were obtained for 75% MG substitution of LT94 fishmeal protein. Further histological examination of liver tissue revealed alterations in hepatic structure associated with higher levels of MG. It was suggested that no more than 25% substitution of fishmeal with maize gluten meal is feasible under the present conditions. In a separate study, catfish fed diets containing different levels of FFSB (58,63 and 63% + DL-methionine) at the expense of fishmeal (LT94), showed significant differences in weight gain. SGR ranged between 3.11 to 2.78, FCR 0.82-0.83 and ANPU between 54.48 to 48.60. Also trypsin activities for intestine ranged between 2.75 to 1.71 Units, liver 1.37 to 1.05 Units and stomach 4.09 to 2.29 Units of activity for increasing levels of FFSB. Hepatic amylase was also reduced from 4.49 to 2.46 Units. General proteolytic activities however, did not show any significant differences between catfish fed different levels of FFSB for the stomach, intestine and liver. The conclusions from each of the nutritional trials were considered and comparisons between the response of tilapia and catfish were made. The advantages of plant based protein concentrates was stressed due to the problems currently existing for animal sources and the expense of fishmeal There were many similarities for the tilapia and catfish and it would seem that both fish species could greatly benefit from improved diet formulations that may meet with their nutritional requirements whilst minimising cost of production. A future strategy of research is presented that includes further work to identify more feed ingredients for potential use in these species.
8

Analysis of sustainability in the pig production chain : life cycle assessment of contrasting scenarios

Olea Perez, Rafael January 2010 (has links)
This research investigated the environmental impact of the pig production chain by modelling contrasting scenarios. Life Cycle Analysis (LCA) and scenario analysis methodologies were used to reveal the main opportunities to improve sustainability. Pig production systems were modelled in two countries (The UK and Mexico), each with a standard production system and on alternative system. This gave four scenarios which were different in the degree of integration that exist between pig and crop production and were then specified in detail to allow for comparison of environmental impact. This study used two strategies to analyse the four scenarios: A pre-assessment facilitated the construction of the system boundary and clarified the processes and commodities which should be included in the Life Cycle Inventory (LCI). A hybrid-LCA method combined a detailed collection of environmental burdens (e-burdens) from the main sources (process-LCA) and a broad compilation of e-burdens from indirect sources (Economic Input Output-LCA). The pre-assessment, conducted as a general LCA, explored novel techniques to construct the system boundary and explore the supply chains in detail. This step clarified the importance of the supply chains of different commodities that are used in the pig farm. The importance of previously reported commodities and processes that mainly contribute to the environmental impact, i.e. feed consumption and manure fermentation were confirmed. Novel findings included the importance of the environmental impacts of goods and services, i.e. machinery, equipment, disinfectants and medicines, that have negligible weight in the impact of environmental indicators that are traditionally analysed (global warming, acidification and eutrophication). The inclusion of novel indicators, such as ozone depression and ecotoxicity to water and soil, demonstrated the importance of including in the LCA those commodities and indicators that have been excluded in many previous studies on the sustainability of pig production. Subsequently, the hybrid-LCA method allowed the expansion of the system boundary of the LCA in a detailed evaluation of each scenario. Results showed the UK scenarios to be superior in management of nutrient flow, by manure management and good agricultural practice. Opportunities to capture methane and recycle nutrients for crop production in the Mexican scenarios were highlighted. In contrast, reduction in machinery and equipment use and fuel consumption were the main opportunities which emerged for the UK scenarios. In addition, specific opportunities to reduce the environmental impact of different pig supply chain sectors were identified in each scenario. In conclusion, the EIO-LCA method allowed for an extension of the traditional system boundary of the LCA, to encompass those e-impacts that have not been included in previous studies. The contrasting of different scenarios allowed emphasis to be placed on opportunities to reduce environmental impact of pig production by highlighting the main challenges in each case. This avoids the controversial issue of denoting a set of specific e-impacts that then favour one production system over another.
9

An investigation of sampling techniques within marine fisheries discards

Allen, M. M. January 2010 (has links)
No description available.
10

Broad-scale Ecological Investigations of Nephrops Norvegicus (L) Burrow Distribution in the Western Irish Sea

Clements, A. J. January 2010 (has links)
No description available.

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