Production traits and disease resistance are believed to be under the control of many genes, i.e. quantitative trait loci (QTL). The objective of the present study was to establish a methodology for identifying DNA markers which are associated with QTL in chickens using an alternative approach to the traditional linkage analysis. A systematic screening approach was designed to search a chicken liver cDNA library for clones which revealed polymorphisms associated with traits. In the first stage of the experiment, a total of 92 cDNA clones were subjected to restriction fragment length polymorphism (RFLP) analysis. About 33% and 22% of the clones revealed DNA polymorphisms at MspI and TaqI restriction sites, respectively. Subsequently, DNA polymorphisms which responded to selection were identified by comparing RFLP frequencies in divergently selected strains of chickens. About 60% of the RFLPs responded to selection for egg production traits and/or Marek's disease (MD) resistance. Trait associations of these RFLPs were then studied by selectively genotyping individuals at the extremes of trait distributions, followed by an analysis of individuals in the entire population and statistical evaluation. Finally, RFLP regions of DNA markers were characterized and PCR assays for rapid RFLP screening were developed. DNA markers in two genes were identified and characterized by this methodology. One was a marker in the chicken mitochondrial genome which arose from a nucleotide substitution (T to C) in the NADH subunit IV gene. Statistical analysis for typing random individual samples from the strains showed that this DNA polymorphism was associated with mature body weight and egg specific gravity which is a strong indicator for egg shell thickness. Other analyzed markers were located in the chicken mitochondrial phospho-enolpyruvate carboxykinase (PEPCK-M). Using the cDNA of this gene as a probe, southern blotting revealed a highly polymorphic band pattern. Statistical analy

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Two experiments were carried out to evaluate the effects of Pearl Millet in combination with different levels of flaxseed and natural pigment (Oro Glo 15RTM) on quantity of n-3 fatty acids in eggs, laying performance and yolk pigmentation. In the first experiment, six different diet treatments were used for six weeks, with 24 hens per treatment (three birds per cage, eight cage replicates). Control diet was a corn-soybean meal diet, and diets containing 0, 2, 4, 8 or 12% ground flaxseed in which all the corn was replaced by pearl millet. In the second experiment, the diet treatments consisted of pearl millet and three inclusion levels of ground flaxseed (4%, 6% and 8%) and two levels (0.1% and 0.2%) of natural pigment in a factorial arrangement. The experiment lasted for twelve weeks, with 18 hens per treatment (three birds per cage, six cage replicates). In each of the experiments, all the diets were formulated to be isocaloric and isonitrogenous and to meet or exceed NRC requirements. Body weight of the birds and feed consumption were recorded at weekly (first experiment) and biweekly (second experiment) intervals. Number of eggs and egg mass produced were measured and recorded on a daily basis. At the end of each of the experiments, all the hens were euthanized to determine liver integrity. In both of the experiments, flock performance parameters were not different among treatments. In regard to egg traits, in the second experiment after 8 week of the start of the experiment, birds fed with diets containing 8% flaxseed produced significantly ( P < 0.05) smaller eggs compared to hens fed 4% flaxseed. Yolk pigmentation was lower (P < 0.05) for the eggs produced by hens fed diets containing pearl millet compared with those produced by feeding corn-based diet. However, 0.1% or 0.2% inclusion of the pigment both proved to be suitable to restore yolk pigmentation to marketable levels. No difference was observed among diets in regard to liver haemorrhage. Evaluation of FA profiles indicated that birds fed a diet containing PM as the sole grain source, and low levels of flaxseed (6%) can produce eggs with more than 350 mg/egg of n-3 FA, which is the lower standard to market eggs as "n-3 FA enriched". / Keywords: laying hens, pearl millet, flaxseed, natural pigment, flock performance, eggs, liver haemorrhage.

Parasites are thought to have large effects on their host populations, driving genetic change, population density changes, speciation and be a major selective force maintaining sexual reproduction. Indirect signatures of parasite-mediated selection are common, but explicit examples of parasite-mediated selection in nature are lacking. In this thesis I examine parasite-mediated dynamics in a natural population of Daphnia magna that experiences an annual epidemic of the bacterial pathogen Pasteuria ramosa. I also test a novel hypothesis investigating the relationship between parasitism and the production of resting eggs. In chapter 2 a combined field study and laboratory infection experiment illustrates one of the best examples of parasite-mediated selection in a natural population, with Daphnia collected after a parasite epidemic having higher levels of parasite resistance than those collected before. This chapter also explored the relationship between parasitism and resting eggs, which are only produced during the sexual phase of reproduction. Daphnia that were reproducing sexually in the field prior to the parasite epidemic were more susceptible, supporting higher levels of parasite growth, than their asexual counterparts. This supports the idea that some genotypes invest in sex at the expense of parasite resistance. In chapter 3 I used molecular markers to investigate genotype frequency changes in the same population in relation to the parasite epidemic. The parasite epidemic was found to be associated with genetic change in the population, and a laboratory infection experiment revealed that the genotype most resistant to the parasite was also most common following the peak of the parasite epidemic. While chapter 2 explored a genetic relationship between susceptibility and resting eggs, chapter 4 explores whether crowding conditions, cues indicating parasite prevalence in the population, or direct exposure to parasite spores can induce resting egg production. I found that crowding conditions or parasite prevalence enhance levels of male and resting egg production, but patterns were entirely dependent on Daphnia genotypes. There was no indication that exposure to parasite spores affects levels of sexual reproduction.

Omega-3 enriched eggs serve as an important functional food to boost consumption of polyunsaturated fatty acids (PUFA) critical for good health. Because omega-3 eggs have the potential for unpleasant aromas and flavours, this research was designed to assess the fatty acid profile and sensory attributes of eggs procured from hens consuming designer diets. In the first study, the use of hemp in hen diets led to significant increases in omega-3 PUFA content and colour intensity of yolks, but did not have adverse effects on the sensory profiles of cooked eggs. Additionally, the level of docosahexaenoic acid was the same in eggs from both the lowest and highest hempseed oil groups. In order to overcome this plateau, the second study assessed diets varying in linoleic acid (LA) content. Although docosapentaenoic acid in the yolk was significantly increased with an increasing dietary LA content, docosahexaenoic acid remained unaffected by dietary treatment. In the third study, a different approach was used to reduce competition between alpha-linolenic acid (ALA) and LA. Diets containing two levels of ALA and varying ratios of saturated fatty acids (SFA): LA + oleic acid (OA) were tested. Increasing dietary SFA: LA + OA resulted in marked increases in all n-3 PUFA. The fourth study was designed to assess the interaction between dietary constituents on sensory attributes of eggs, namely omega-3 PUFA from flaxseed oil (FO), and canola meal (CM), which contains precursors to trimethylamine, which may lead to fishy taint. Oceanic flavour significantly increased with inclusion of FO, while egg, creamy and buttery flavours showed a decrease. The pairing of CM and FO resulted in a significant decrease in egg flavour compared to using FO alone. This research has demonstrated that novel ingredients like hemp can be used in laying hen diets to deposit n-3 PUFA into eggs without fear of affecting sensory outcomes. Increasing the SFA: LA + OA ratio in layer diets is most effective in increasing yolk ALA conversion into long-chain PUFA. Lastly, CM should be added to diets with caution when used in conjunction with omega-3 PUFA ingredients due to a reduction in egg flavour.

The most successful method used for improving the growth rate of broilers is genetic selection. Improvements in nutrition, housing and disease resistance have been impressive, yet genetic selection is purported to have contributed the majority of the tremendous increase in growth rate that has taken place over the past 50 years (McKay, 2008). Many selection strategies are available, but not all are suitable, as the choice is dependent on the objective of the breeder. Selection strategies are bound to change over time as different traits become more important, and this has been the case in the broiler industry: focus was initially placed predominantly on growth rate, but the negative genetic correlation that exists between growth rate and reproductive and liveability traits has forced breeders to change their position, especially as growth rate has almost reached its upper limit and reproductive traits lag behind. This has resulted in a change from single trait to multiple trait selection. In the exercise reported here, four selection strategies commonly used for single trait selection, namely individual, between family, within family and family-index selection, were applied to a simulated broiler population using the Monte Carlo method of simulation, and constructed with the use of genetic parameters obtained from the literature. Theoretical and simulated methods of the four selection strategies were compared. A fifth selection strategy, index selection, was applied to represent multiple trait selection. The relative merit of each selection procedure was then compared, as well as the results obtained from the theoretical and simulated methods. Construction of the selection index was complex in comparison to single trait selection, as each trait included in the index had to be assigned an economic value. This value is representative of the relative importance of that trait to the overall profitability, or ability to save costs in the operation. Therefore traits favourable to profitability, or having the ability to reduce production costs, are given a heavier weighting and will consequently achieve a relatively larger improvement when applied to the selection index. A model was constructed using production rates, income and costs to represent the current overall economic situation in the industry. This was then used to determine cost economic values, which represent the saving in cost per unit improvement in each of the economically important traits, and revenue economic values, calculated as the value of each unit improvement attained in each of the economically important traits. Body weight remains the most profitable trait in a broiler enterprise; however breeder egg production is equally important as the industry would fail without sufficient day-old broilers. Therefore, it would be beneficial to determine whether current egg production levels could be maintained, or even improved, whilst improvement is made to the growth rate of the progeny. The above statement was found to be possible with the use of index selection. This multiple trait selection strategy proved capable of defying the negative genetic correlation that exists between body weight and egg production by improving egg production to 60 weeks by eight eggs, and body weight at 35 days by 259 grams. Furthermore, in some cases index selection was able to achieve improvements in some traits greater than those attained with single trait selection, whilst simultaneously improving certain negatively correlated traits. Index selection has illustrated its superiority over single trait selection strategies and its relative value to the poultry industry. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.

In the spring of 2005, a Vancouver Island Health Authority Inspector tried to stop the sale of ungraded eggs at the Saltspring Island Farmers' Market. This event, and the actions that followed, came to be known as the "Saltspring Island egg wars." Using the egg wars as a starting point, I explore the inner workings and contradictions of the egg sector in British Columbia by asking the question "how is it that food grown locally in sustainable ways is seen to be less safe by regulatory food regimes than food produced in the industrial food system?" To do this I take up the standpoint of egg farmers who "farm otherwise." From this grounding I rely on the insights of these farmers, civil servants, and social theorists Antonio Gramsci, Michel Foucault and Dorothy Smith to understand the ordering of power, knowledge and the social in relationships between sustainable egg producers and the British Columbia egg scheme.

Tema:,,Organinio seleno ir vitamino E įtaką vištų dedeklių produktyvumui praturtinant jų lesalus rapso aliejumi‘‘ Atlikimo vieta: Lietuvos sveikatos mokslų universiteto Veterinarijos akademijos Paukščių lesalų ir paukštininkystės produktų laboratorijoje prie Gyvulininkystės katedros. Darbo tikslas: ištirti organinio seleno ir vitamino E įtaką vištų dedeklių produktyvumui bei kiaušinių kokybei, praturtinant lesalus rapso aliejumi. Darbo uždaviniai: 1. Nustatyti organinio seleno ir vitamino E įtaką vištų dedeklių dėslumui, lesalų sąnaudoms, išsaugojimui bei vištų fiziologinei būklei, praturtinant jų lesalus rapso aliejumi. 2. Nustatyti organinio seleno ir vitamino E įtaką kiaušinių kokybiniams ir kiekybiniams parametrams, praturtinant jų lesalus rapso aliejumi. 3. Nustatyti organinio seleno ir vitamino E įtaką jusliniams kiaušinių rodikliams, praturtinant jų lesalus rapso aliejumi. Tyrimo metodika. Lesinimo testas truko 56 dienas ir buvo pradėtas su 30 savaičių amžiaus Lohmann Brown linijų derinio 20 vnt. dėsliųjų vištų. Paukščiai buvo suskirstyti į 2 grupes, kiekvienoje po 10 vištų. Kontrolinės grupės lesalai buvo papildyti rapsų aliejumi, neorganiniu Se ir vitaminu E. Tiriamosios grupės lesalai buvo papildyti rapsų aliejumi, organiniu selenu ir vitaminu E. Testo metu dėsliosios vištos laikytos individualiuose narveliuose su girdytuvėmis bei stacionariomis lesalinėmis, vienodomis laikymo ir lesinimo salygomis sąlygomis. Dedeklės vištos lesintos granuliuotais... [toliau žr. visą tekstą] / Theme: ,,The influence of organic selenium and vitamin E for productivity of laying hens when the birdseed is enriched with canola oil”. Research place: Lithuanian University of Health Sciences, Veterinary Academy, Laboratory of Poultry Nutrition’s and Poultry Products by Department of Animal Sciences Purpose of the study: to explore the influence of organic selenium and vitamin E on productivity of laying hens when their food is enriched with canola oil. Goals of the study: 1.To determine the influence of organic selenium and vitamin E on productivity of laying hens, feed consumption, preservation and physiological state of hens when their food is enriched with canola oil. 2. To determine the influence of organic selenium and vitamin E on qualitative and quantitative parameters of eggs when the birdseed is enriched with canola oil. 3. To determine the influence of organic selenium and vitamin E for sensual indicators of eggs when the birdseed is enriched with canola oil. Research methodology: The feeding test was going on for 56 days with 30-week old 20 laying hens of Lohmann Brown line match. The hens were divided into 2 groups, in every group 10 hens. The birdseed of controlled group was enriched with canola oil, non-organic Se and vitamin E. The birdseed of the exploratory group was enriched with canola oil, organic Se and vitamin E. During the test the laying hens have been kept in individual birdcages with water supplies and steady-state feed-troughs under the same... [to full text]

Lesinimo bandymas truko 56 dienas ir buvo atliktas su 30 savaičių Hisex Brown linijų derinio 36 vnt. dėsliųjų vištų. Paukščiai buvo suskirstyti į 3 grupes, kiekvienoje grupėje po 12 vištų. Visų grupių vištos buvo lesinamos standartiniais kombinuotaisiais lesalais. Kontrolinės grupės vištos buvo lesinamos tik standartiniais kombinuotaisiais lesalais, į I tiriamosios grupės kombinuotuosius lesalus buvo įmaišyta organinių rūgščių priedo, kurio dozavimas 1,5 kg/t lesalų, į II tiriamosios grupės kombinuotuosius lesalus įterpta organinių rūgščių priedo 2 kg/t lesalų. Lumance priedai – 1,5 kg/t ir 2,0 kg/t – esminės įtakos vištų masės dinamikai nebuvo nustatytas. Minėti priedai mažino vištų dėslumą sumažino 2-4 proc., o lesalų konversijai bei išsaugojimui esminės įtakos nenustatyta. Naudoti Lumance priedai sumažino tyrimų vištų masę 3-5 proc. Lumance priedas 1,5 kg/t lesalų padidino lukšto stiprumą 10 proc., baltymo aukštį 9 proc., Hafo vienetus – 6 proc., lukšto storį – 3 proc., palyginus su kontroline grupe. Lumance priedai omega – 6 ir omega – 3 kiekiui bei santykiui, hypocholesterolemijos/hypercholesterolemijos, peroksidavimosi, aterogeniškumo ir trombogeniškumo indeksams tiek šviežiuose kiaušiniuose, tiek sandėliuotuose 28 dienas esminės įtakos neturėjo. Juslinės šviežių kiaušinių baltymo ir trynio savybės buvo labai artimos, nenustatyta, kad naudoti priedai būtų turėję reikšmingos įtakos kvapo, skonio, spalvos ar tekstūros savybių intensyvumui. Išlaikius kiaušinius 28 paras... [toliau žr. visą tekstą] / The feeding experiment took 56 days and was performed on the 36 Hisex Brown layer fowl of 30 weeks old. Hens were divided into 3 groups of 12 hens in each. The fowl of all 3 groups were fed with a standard composite feed. The fowl in the auditorial group were only fed with the standard composite feed whilst the composite feed of the first investigative group was mixed with an organic acid supplement of a dosage 1,5kg/tn of feed and finally the composite feed of the second investigative group was combined with an organic acid supplement of a dosage 2kg/tn of feed. The influence was not detected of the Lumance supplements (1,5kg/t and 2kg/t) to the body growth of the fowl. The mentioned supplements reduced fowl productivity by 2-4% however the influence was not detected to the conversion of feed and preservation. Used Lumance supplements reduced the body weight of examined fowl by 3-5%. Lumance supplement of 1,5kg/t feed increased the strength of the hull by 10% and the height of albumen by 9%, the units of Haf – by 6% and the thickness of the hull by 3% in comparison with the auditorial group. Lumance accessories omega - 6 and omega - 3 and the quantity proportion hypercholesterolemia/ hypercholesterolemia, peroxidation, atherogenic and thrombogenicity indices both fresh eggs and warehoused for 28 days had no significant influence.The sensual features of yolk and albumen of fresh eggs were very close and it was not established a significant influence of the used supplements... [to full text]

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