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

Two experiments were conducted to evaluate the effects of arginine, vitamin E, and their combination on cardiopulmonary performance and nitric oxide synthase (NOS) activity in broilers undergoing cold-induced ascites (pulmonary hypertension) after an acute challenge with epinephrine. One day-old male broilers ( n = 25/treatment) were supplemented with arginine (0.3% water supplementation), vitamin E (400 IU/L or kg, water or feed supplementation; experiment 1 and 2 respectively) or both compounds, above NRC (1994) recommendations. From day 28 to 42, a catheterization was performed (n = 8/treatment) to evaluate pulmonary and mean arterial pressures, and heart rate. After recording baseline values, two injections of epinephrine (1 or 0.5 mg/kg body weight, experiment 1 and 2, respectively) were administered in a 20 min interval. The NOS activity was estimated through the conversion of 14C-arginine to 14C-citrulline in isolated pulmonary arteries ( n = 8/treatment). Overall, the time taken for pulmonary arterial pressure to return to values no different from initial baseline levels was longer for the birds consuming high levels of vitamin E (alone or in combination with arginine) compared to birds supplemented only with arginine. Although NOS activity was highly variable, birds fed with high arginine levels tended to have the lowest NOS activity. These results showed that vitamin E supplementation at the levels used in these experiments has detrimental effects on cardiopulmonary performance, and does not improve NOS activity in isolated pulmonary arteries.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1935. / Typescript. With this are bound: The effect of feeding high amounts of soluble iron and aluminum salts / H.J. Deobald and C.A. Elvehjem. Reprinted from American journal of physiology, vol. 111, no. 1 (Feb. 1935), p. 118-123 -- Availability of calcium salts for chicks / by H.J. Deobald, C.A. Elvehjem, E.B. Hart, and J.G. Halpin. Reprinted from Poultry science, vol. XV, no. 1 (Jan. 1936), p. 42-47. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph.D.)--Mississippi State University. Department of Food Science, Nutrition, and Health Promotion. / Title from title screen. Includes bibliographical references.

Made available in DSpace on 2014-06-11T19:33:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-08-20Bitstream added on 2014-06-13T19:04:33Z : No. of bitstreams: 1 boschiero_c_dr_botfmvz.pdf: 635473 bytes, checksum: feca4297f6abf36be6a9c8cf72ce1eb6 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Universidade Estadual Paulista (UNESP) / A partir de resultados de um estudo anterior, no qual foram mapeados QTLs para características de peso vivo, peso do coração e pulmões no GGA1, foi definida uma região no intervalo entre os marcadores ADL0234 e LEI0071, abrangendo 82,3 cM. Foram avaliadas três famílias de meios-irmãos paternos que compreendiam sete famílias de irmãos completos, num total de 652 F2 para as características: peso vivo aos 35 e 41 dias de idade, pesos do coração e pulmões e rendimentos de coração e pulmões. Os genótipos de seis marcadores microssatélites foram adicionados aos dez utilizados anteriormente. O mapa de ligação obtido da região compreendeu 110,8 cM com espaçamento médio entre os marcadores de 7,4 cM. Na análise de F2, em um único intervalo (LEI0146-LEI0174), compreendendo 28,8 cM, foram mapeados QTLs para todas as características estudadas, com exceção dos rendimentos de coração e pulmões. Neste intervalo estão localizados o gene IGF1 e o centrômero do cromossomo. A adição de seis marcadores confirmou os QTLs mapeados anteriormente, porém alguns em diferentes posições. A análise de meios-irmãos paternos indicou que os principais QTLs estavam segregando em apenas uma das famílias (7716), na qual cinco QTLs foram mapeados. Na análise de meios-irmãos maternos, duas famílias segregaram QTLs tanto na análise Individual como na Conjunta (7810 e 7971). As diferentes análises permitiram selecionar dois casais F1, que devem ser o alvo dos próximos estudos. Este estudo restringiu a busca por genes candidatos responsáveis pelas características de interesse a uma região de 28,8 cM (9,82 Mb) no GGA1. / Based on the results from a previous study, in which QTL for body weight, heart and lungs weights and heart and lungs percentages were mapped to GGA1, a region was defined between markers ADL0234 and LEI0071, spanning 82.3 cM. Three paternal half-sib families, comprising seven full-sib families, totaling 652 F2 were evaluated for body weight at 35 and 41 days of age, heart and lungs weights and heart and lungs yields. Genotypes of six microsatellite markers were added to those of ten previously used. The linkage map of this region spanned 110.8 cM, with average spacing of 7.4 cM between markers. In a single interval (LEI0146-LEI0174), comprising 28.8 cM, QTLs for all traits, except for heart and lungs yields were mapped in the F2 analysis. In this same interval the IGF1 gene, and the chromosome centromere, are located. The use of six additional markers confirmed the same QTLs mapped previously, but some of them, in different positions. The paternal half-sib analysis indicated that the main QTLs were segregating in one of the families only (7716), in which five QTLs were mapped. In the maternal half-sib analysis, two families segregated QTLs both, in the across and within families analyses (7810 and 7971). These analyses allowed the selection of two F1 couples to be the target for future studies. This study restricted the search for candidate genes responsible for the traits of interest to a region of 28.8 cM (9.82 Mb) in GGA1.

Thesis (M.A. Agricultural Management (Animal Production)) -- University of Limpopo, 2016 / A total of 320 male and female day old Ovambo and Potchefstroom koekoek (PK) chickens, were randomly assigned to a 2 (breed) × 2 (sex) factorial arrangement in a completely randomised design. Meat quality traits of male and female Ovambo and Potchefstroom Koekoek chickens were evaluated in this comparative study. The chickens were raised from day-old and fed on a commercial grower diet with 11.5 MJ/ME kg DM and 20% crude protein. The carcass traits of the Ovambo and Potchefstroom Koekoek (PK) were similar (P>0.05) except for breast yield. Sex affected on all carcass traits. Breed, sex, and time interactions influenced colour parameters of thigh and drumstick meat except redness (a*) and yellowness (b*) values of chicken breast meat. The pH varied significantly (P<0.05) between the breeds, sex and time period. The sensory evaluations of the chicken breeds were similar (P>0.05). However, tenderness of the breast meat as measured by shear force was higher for PK than that of Ovambo chickens. Fatty acid profiles of the chickens were not affected (P>0.05) by breed or sex. The ratios of n-6 and n-3 fatty acids were significantly lower in both breeds which are desirable in reducing the risk of many heart-related diseases. The information obtained from this study can assist efforts to promote production of indigenous chickens. The information also sheds some light in terms of consumer awareness for healthier meat choices. Keywords: Breed, Carcass traits, Meat colour, meat pH, Fatty acids

Thesis (M.A. (Agricultural Extension)) -- University of Limpopo, 2015 / The aim of the study was to analyse the socio-economic factors affecting the gross margin of small-scale broiler producers in the Vhembe district and thereby determine their profitability and contribution towards the local economic development. The population comprised of small-scale broiler producers who reared between100 and 3200 birds in the Vhembe district. A total of 94 out of 311small-scale broiler producers were selected using a simple random- sampling procedure. Data on different socio-economic parameters was collected through personal interviews using a semi-structured questionnaire. Descriptive statistics was computed using FREQ COUNTS procedures to describe the characteristics of small-scale broiler producers. Gross margin analysis was used to calculate the profitability for small-scale broiler producers. The Multiple Linear Regression was used to estimate the influence of socio-economic factors influence on the gross margin of the small-scale broiler producers. Multiple Regression analysis indicated that small-scale broiler producers in the Vhembe district were making profit. Socio-economic variables such as age of the farmer, farming experience, flock size, training received by the farmer, market access and record keeping, educational level, household income and extension services were found to have positive correlation with the small-scale broiler producers‟ gross margin. To effectively address production constraints affecting gross margin of small-scale broiler producers, it is, therefore, fundamental to consider their socio-economic profiles.

Thesis (MSc. Agriculture (Animal Production)) -- University of Limpopo, 2015 / Three experiments were conducted to determine the effect of in ovo glucose injection on egg hatchability, chick hatch-weight, productivity and carcass characteristics of indigenous Potchefstroom koekoek chickens. A complete randomized design was used in all the three parts of the study (from incubation, 1-49 days old unsexed chickens and 50-91 days old female chickens). On day 18 of incubation the developing eggs were subjected to the following treatments: 0- (no glucose or water injected), 0+ (only water injected), 5, 10, 15 or 20 mg of glucose per egg. Each treatment had three replications and there were 20 eggs per replicate. A quadratic model was used to determine in ovo glucose injection levels for optimal egg hatchability, chick hatch-weight and chick to egg weight ratio of Potchefstroom koekoek chickens. In ovo glucose injection improved (P<0.05) egg hatchability, chick hatch-weight and chick to egg weight ratio of the chickens. Egg hatchability, chick hatch-weight and chick to egg weight ratio Potchefstroom koekoek chickens were optimized at different injection levels of 4.50, 10.43 and 12.00 mg of glucose per egg, respectively. Unsexed day-old chicks from the first experiment (according to their initial treatments and replicates) were used in a complete randomized design having six treatments, replicated three times, and having ten birds per replicate. Glucose injection levels increased (P<0.05) feed intake, growth rate, feed conversion ratio, live weight, metabolisable energy and nitrogen retention of female Potchefstroom koekoek chickens aged 1 to 49 days. However, growth rate, live weight, metabolisable energy intake and nitrogen retention of the chickens were optimized at glucose injection levels of 3.92, 4.36, 10.67 and 13.50 mg per egg, respectively. Female chickens from the second part of the study (according to their initial treatments and replicates) were used in a complete randomized design having six treatments, replicated three times, and having five birds per replicate. In ovo glucose injection levels improved (P<0.05) on feed intake, growth rate, feed conversion ratio, live weight, metabolisable energy and nitrogen retention of female Potchefstroom koekoek chickens aged 50 to 91 days. However, only feed conversion ratio and metabolisable energy intake of the chickens were optimized at glucose injection levels of 12.15 and 5.57 mg per egg, respectively. Injection level also improved (P<0.05) carcass, breast, v drumstick, thigh, wing, gizzard and liver weights of female Potchefstroom koekoek chickens aged 13 weeks. In ovo glucose injection increased (P<0.05) breast meat tenderness, juiciness and flavour of female Potchefstroom koekoek chickens aged 91 days. However, breast tenderness, juiciness and flavour of female Potchefstroom koekoek chickens were optimized injection levels of 13.50, 19.25 and 10.83 mg of glucose per egg, respectively. No chicken deaths were observe

MSCAGR (Animal Science) / Department of Animal Science / See the attached abstract below

No description available.