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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.
51

Evaluation of the energetic contribution from gut fermentation in growing pigs

Zhu, Jin-Qian January 1988 (has links)
The aim of this study was to evaluate the growth supporting value of DE derived from gut fermentation in growing pigs. Unmolassed sugar beet pulp (SBP) was selected as a model material for fermentation. For a reference material which would be digested in the small intestine by the endogenous enzymes, maize starch (MS) was selected. A cereal-based control diet was formulated to fulfil the needs of pigs for all essential nutrients apart from energy. To this control diet, either SBP (150 & 300 g/kg) or MS (100 & 200 g/kg) were added. The study consisted of two phases. The first phase (digestion trial and growth trial) was devoted to studying the digestion of these diets and to comparing the effects on growth of pigs of the two DE sources (SBP and MS). The second phase was to determine the production of VFA resulting from the fermentation of SBP. Methods used included stoichiometric calculations based on measurements of the molar proportions of VFA combined with CH4 production, and a direct assessment of the true fermented materials using antibiotics to suppress fermentation. The results of the first phase showed that the energy in SBP and MS had an apparent digestibility of 0.74 and 0.98. The DE from SBP was used for supporting carcass gain with an efficiency of 0.57 of the DE from MS. The results of the second phase indicated that measurements of methane production alone or even with inclusion of free hydrogen could underestimate the extent of fermentation in the gut of pigs. The results also suggest that with the cereal-based control diet, fermentation could supply up to 13.6% of the dietary DE in the form of VFA or 18.0% in the form of fermented energy. For this control diet incorporating 30% SBP, the respective values were 25.4% and 33.4%. The absorbed VFA resulting from the fermentation of SBP had a growth supporting value of 0.763 of that of absorbed glucose from MS.
52

Role of insulin-like growth factors and type I receptors in the developing porcine intestine

Morgan, Catherine J. January 1995 (has links)
The role of the IGF system during intestinal development of the pig, and in particular the significance of dietary IGF-I was investigated. Significant concentrations of IGF-I and IGFBP were measured in milk and colostrum and in vitro immunoaffinity chromatography studies confirmed IGF-I stability in the presence of newborn and suckled intestinal contents. Specific IGF-I receptors were identified on apical and basolateral membranes, and the cytoplasm of villus/crypt enterocytes. Receptor binding data revealed binding to a single site, with an affinity of 1nM. Receptor affinity remained constant during development but in apical microvillar membranes, IGF-I receptors were transiently up-regulated in suckled animals. The specificity of receptors was confirmed using competition binding and affinity crosslinking studies, and the functional activity of receptors demonstrated using an in vitro receptor autophosphorylation assay. In Caco-2 intestinal cells IGF-I binding and IGF-I receptor mRNA expression was significantly increased in the presence of 7 and 14 day milk, suggesting that milk-borne factors may regulate the up-regulation observed in vivo. In vivo experiments were undertaken using colostrum-fed and colostrum-deprived artificially-reared pigs. Significant differences in plasma IGF-I and IGF binding proteins were observed in the IGF- treated animals compared to controls suggesting that IGF-I remained bioactive in the intestine and was transported to the circulation. The in vivo effects of IGF-I were modulated by early nutrition. Plasma IGF-I increased in colostrum-deprived animals, whereas in colostrum-fed animals levels decreased.
53

Study of Actions Taken by Taiwan Pork Producers After the Open of Taiwan Pork Market

SUNG, TSENG-SHOU 25 August 2005 (has links)
ABSTRACT The pig industry is one of the important industry for rural economy development in Taiwan¡CGross production value is about NTD 100 billion¡Awhich accounts for 51% and 16% respectively of animal husbandry and agricultural production value¡CIt is estimated around six hundred persons are engaged in related field of pig industry¡CTherefore¡Ain addition to proper rural economy¡Apig industry is also an important factor for social stability¡C Before foot-and-mouth disease outbreak in Taiwan in 1997¡Ait was a gold era for Taiwan pig industry¡Aas Taiwan export big amount of pork to Japan¡CHowever pork export suddenly stopped due to FMD outbreak¡Aswine producer suffered enormous economic losses¡C In order to enter WTO¡Ain 1998 Taiwan agreed to open pork import by the way of increasing quota progressively¡Aand then ¡Ain 2005¡Aopen pork import in all-round way¡C Because of high labor and land cost plus high cost to prevent environment pollution¡ATaiwan pork cost is generally higher than that in the main pork producer¡CFortunately¡Apeople in Taiwanese prefer warm body pork than imported frozen pork at present¡CImported pork is mainly used in pork processing industry¡Ait has not caused immediate threat to the domestic pork¡CImported pork only accounted for 7.2 % of total pork consumption till 2003¡C Facing the situation¡ACOA(Council Of Agriculture) has drafted a complete plan to support swine producer¡CIn this research¡Athree representative pig farms were choosed for depth interview, and than carry on questionnaire interview to 139 different scale swine farmers located in different area¡CThe result shows swine farmers think that the open of pork market in an all-round way will influence the industry development, but the majority does not cherish the pessimistic attitude¡CThey think except open of pork market¡Athere are many other factors¡Asuch as high morbidity of swine disease¡Bwaste water treatment¡Bgovernment¡¦s industrial policy etc¡Awill impact pig industry development¡C According to the survey results¡A43% of swine farmer have taken some actions to face the open of pork market, the major actions include to improve breed stock¡Bto create brand pork¡Bgood swine farm authentication¡Bto enter pig cooperative society and to raise black hair pig¡C Key Word ¡Gopen of pork market¡Apig industry
54

Effect of cryoprotectant on the cryopreservation of South African Kolbroek pig semen

Mapeka, MH, Lehloenya, KC, Nedambale, TL, Sutherland, B January 2009 (has links)
Abstract The study evaluated the effect of different cryoprotectants on post-thaw survival and motility of Kolbroek sperm. Semen from Kolbroek boars was collected with the gloved hand technique. Ejaculates were diluted with Beltsville thawing solution (BTS) at a ratio of 1 : 1 prior to freezing. Semen was diluted with egg yolk tris; thereafter, one of the three cryoprotectants (14% glycerol, 14% DMSO or 7% glycerol + 7% DMSO) were added. Diluted samples were then loaded into 0.5 mL straws and cooled with a programmable freezer. Thereafter the semen straws were plunged directly into liquid nitrogen (-196 °C) and stored for 48 h. Frozen straws were thawed at 39 °C for a minute and evaluated for sperm motility and survival at 0, 30, 60 and 90 min post-thaw. The post-thaw sperm survival frozen using glycerol as a cryoprotectant was significantly higher immediately after thawing, compared to DMSO, however, similar to the combination of glycerol and DMSO. There was no significant difference on motility rate immediately (0 min) post-thaw between the three cryoprotectants. Sperm cryopreserved with glycerol exhibited a significantly higher percentage motility at 30, 60 and 90 min post-thaw than in the other cryoprotectants. Based on sperm motility, glycerol was a better cryoprotectant for cryopreservation of Kolbroek boar sperm.
55

Investigation of growth performance and immunomodulatory factors associated with the hepatic gene expression of the insulin-like growth factor system in nursery pigs

Slifierz, Mackenzie 06 September 2013 (has links)
The insulin-like growth factor (IGF) system is an important determinant of growth in animals and recent findings suggest that immunomodulatory activity may regulate the IGF system independent of nutritional parameters. A cross-sectional study of the hepatic gene expression of the IGF system (IGF-1, IGFBP-3, GHR) and immunomodulatory agents (CRP, Hp, SAA, IL-1β, IL-6, IL-10, IL-18, IFN-α, IFN-γ, TNF-α) in nursery pigs (n=168) from 8 farms was completed. Production parameters and swine pathogens (Salmonella spp., L. intracellularis, Brachyspira spp., ETEC, MRSA, SIV, and PRRSV) were also assessed in relation to the IGF system. Hepatic expression of IGF-1, IGFBP-3, and GHR was associated with growth performance and was inversely associated with several immunomodulatory agents including Hp, SAA, IL-1β, IL-18, and TNF-α. These findings suggest that elevated levels of proinflammatory agents may dysregulate the transcriptional expression of the IGF system in hepatic tissue and consequently affect the growth and metabolism of nursery pigs. / Swine Innovation Porc
56

Physiological effects of recycled rumen contents in the diet of the guinea pig

Escurra-Meneses, E. January 1988 (has links)
No description available.
57

The establishment of pregnancy in prolific Chinese Meishan and Large White x Landrace gilts : a comparative study

Pickard, Amanda Rachael January 1996 (has links)
Chinese Meishan pigs exhibit exceptional prolificacy compared with common domestic breeds and therefore provide a model for investigating the mechanisms involved in a successful reproductive outcome. Previous studies have shown that the Meishan gains its reproductive advantage through reduced conceptus mortality at the time of conceptus attachment to the uterine endometrium and the establishment of pregnancy. The purpose of this thesis was to consider factors that might affect conceptus viability in the Meishan and a control breed (the Large White x Landrace), to determine where differences arise. Meishan and Large White x Landrace function was compared, in the period leading up to the establishment of pregnancy (days eight to 12 after the onset of oestrus, inclusive). Many factors that might impinge on conceptus survival were investigated, including maternal nutrition, metabolism, endocrinology and conceptus and endometrial morphology and biochemistry. Conceptus oestradiol-17β secretion, believed to be the signal for the establishment of pregnancy in the pig, was delayed and more synchronised in the Meishan than in Large White x Landrace. Also, Meishan plasma progesterone concentrations were elevated compared with the Large White x Landrace gilts. Other studies have positively correlated conceptus survival with raised plasma progesterone concentrations, which can be manipulated by altering the nutritional intake of the dam. The role of conceptus oestradiol-17β in the establishment of pregnancy in the Meishan was also investigated. A lack of aromatase enzyme activity, before day 12 after the onset of oestrus, prevents the conversion of testosterone to oestradiol-17β. Thereafter, substrate availability limits the reaction. Exogenous oestradiol benzoate extended the interoestrous interval of treated Meishan gilts, although differences in the physiology of pregnant and pseudopregnant gilts suggested that other conceptus-specific activity influences the establishment of pregnancy in this breed. These studies have highlighted specific aspects of pig reproduction, manipulation of which might improve the prolificacy of domestic breeds. Further investigations are required to establish the whether such techniques would be practical in the commercial setting.
58

Multiple opioid binding sites and their ligands

Paterson, S. J. January 1986 (has links)
The presence of μ-, δ- and κ-binding sites in homogenates of guinea-pig brain was demonstrated by the use of selective labelling techniques. In saturation experiments, the tritiated ligands [^3H]-[D-Ala^2, MePhe^4, Gly-ol^5]enkephalin, [^3H]-dihydromorphine, [^3H]-morphine and [^3H]-dihydronormorphine labelled only the μ-binding site. The δ-binding site could be labelled selectively with [^3H]-[D-Pen^2, D-Pen^5]enkephalin. However, the less selective δ-ligand, [<sup>3</sup>H]-[D-Ala<sup>2</sup>, D-Leu<sup>5</sup>] enkephalin, could only be used when its μ-binding was blocked with the unlabelled μ-ligand [D-Ala<sup>2</sup>, MePhe<sup>4</sup>, Gly-ol<sup>5</sup>]enkephalin. Selective labelling of the κ-binding site was more of a problem since the non-selective ligands [^3H]-etorphine, [^3H]-(±)-ethylketazocine and [<sup>3</sup>H]-(-)-bremazocine bind to the μ-, δ- and κ-sites. Therefore, the κ-binding site could only be labelled selectively when the binding of the tritiated ligands to the μ- and δ-sites was prevented by addition of the unlabelled μ-ligand [D-Ala^2, MePhe^4, Gly-ol^5]enkephalin and the unlabelled δ-ligand [D-Ala<sup>2</sup>, D-Leu<sup>5</sup>]enkephalin. By analysis of the saturation curves obtained using these selective labelling techniques, the proportion of binding sites in homogenates of guinea-pig brain at 25°C was 24% μ-sites; 32% δ-sites and 44% κ-sites. The selective labelling techniques were also used to label the μ, δ- and κ-sites in displacement assays. The compounds with the highest degree of preference for each binding site were: for the μ-site, [D-Ala^2, MePhe^4, Gly-ol^5]enkephalin and Tyr-Pro-MePhe-D-Pro-NH_2; for the δ-site, [D-Pen<sup>2</sup>, L-Pen<sup>5</sup>]enkephalin, [D-Pen<sup>2</sup>, D-Pen<sup>5</sup>]enkephalin and ICI 174864 and for the κ-site, U-50,488H and U-69,593. As far as antagonists were concerned, naloxone displayed the highest preference for the μ-binding site and Mr 2266 had a preference for the κ-binding site but neither compound was highly selective unlike the δ-antagonist ICI 174864. The effect of pre-incubation with β-funaltrexamine on opioid binding was investigated in homogenates of guinea-pig brain and myenteric plexus-longitudinal muscle.
59

Growth, feed intake and diet selection in pigs : theory and experiments

Kyriazakis, I. January 1989 (has links)
A theory of growth and feed intake in the pig is proposed and the results of five experiments to test it are reported here. An attempt is first made to describe the potential growth in pigs, that is, growth under non-limiting conditions; the conditions needed to allow potential growth to be retained are then considered. Two ways of providing non-limiting feeding conditions are discussed: a single balanced feed and a set of feeds given as a choice. In addition, a model which predicts the voluntary feed intake of pigs is also developed and tested in experiments. The results from pigs offered single feeds in the first two experiments were consistent with the predictions of the model, which were that the rate of feed intake would increase as the protein content of the feeds was decreased. The size of the increase depended on the ability of the pig to lose heat. In these experiments, when pigs were offered a pair of feeds as a choice, a combination of which was non-limiting, the results suggested that this method cannot be successfully used to attain the potential growth of pigs. The diet selection results were characterised by a considerable variation in the diets selected by individual pigs, and only some pigs achieved what was estimated to be their potential rate of growth. It was suggested that pigs which failed to select a non-limiting diet did not have the necessary chance to choose. Experiment 3 evaluated a simple method of ensuring that pigs are given both the necessary choice, and the chance to choose. This was achieved by giving them the opportunity to sample the single feeds, which were to be offered as a choice, alone on alternate days for a short period of six days. Subsequently, pigs given a choice between two feeds were able to select a non-limiting diet. Experiment 4 incorporated the method established previously and consisted of a severe investigation into the rules of diet selection. It was concluded that pigs are able to avoid excess of nutrient, in this case protein, intake or to select the best possible diet in less favourable conditions, ie. a choice between two limiting feeds. The last experiment consisted of an extended test of the theory that a pig will select a diet which is a reflection of its degree of maturity, state and sex. Pigs made fat and delayed in growth in one period were subsequently given the opportunity to recover on a pair of feeds offered as a choice. The diets selected by the fat pigs satisfied their requirements for compensatory protein gain allowing only a slow rate of lipid gain. In addition, they met the different growth and fattening requirements by the two sexes. All these findings are discussed in relation to the use of choice-feeding as an independent test of other estimates of resource requirements, as a feeding technique when the potential growth of pigs is to be observed and as a help in predicting the feeding behaviour in pigs.
60

The digestion and utilisation of food fibre by growing pigs

Stebbens, Helen Rose January 1988 (has links)
A series of investigations were undertaken to provide information for compounders to consider when including fibrous foods in diets for growing pigs. The work involved measurements of nutrient digestibilities, growth trials and calorimetric studies. The digestibility of the neutral detergent fibre (NDF) fraction of a food was dependent on a number of factors including the source of fibre, the adaptation period and liveweight of the pig, and the protein and lipid contents of the diet. The level of addition of food fibre was not important in determining the digestibility of the NDF component of a fibre source, whereas an inverse relationship was found between the digestibility of nitrogen and energy, and the level of added food fibre. It was concluded that increasing the level of addition of food fibre is more important in determining the depressive effect on the digestibility of non-fibre components than its own. Rapid growth was achieved when young, weaned and growing pigs were given diets containing wheatfeed and sugar-beet pulp. A substantial part of the energy supplied was in the form of VFA produced by the fermentation of non-starch polysaccharides in the wheatfeed and sugar-beet pulp. A growth trial with diets containing sugar-beet pulp and maize revealed that fermented energy from beet pulp was used with an efficiency of 0.72 that of the energy of maize. The apparently digested energy arising from the fermentation of non-starch polysaccharides, therefore, does not correspond directly in terms of potential use to the animal with that obtained by the enzymic digestion of maize starch. A net energy value for sugar-beet pulp was also calculated. This work has shown that wheatfeed and sugar-beet pulp may be useful as dietary ingredients for growing pigs. However, growth rates may be slightly depressed due to a lower efficiency of utilisation of apparently digested energy from the fibrous fraction of the diet. This could lead to on farm problems associated with a decreased throughput eg overstocking. However, the use of a corrected digestible energy value and ileal digestibilities of amino acids for a fibrous food, when formulating rations, could lead to an improvement in the prediction in performance. As well as the nutritional aspects of feeding fibrous foods, there are also a number of non-nutritional factors which will influence the use of fibrous materials and these are discussed in the light of their practical implications for the feeding of fibrous foods to pigs.

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