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<p>The objective of this thesis was to investigate the effect of dietary enzymatically treated yeast (ETY) in weanling pigs and evaluate the effect of ETY in broiler chickens during a coccidia challenge. Two studies were carried out to investigate this objective.</p> <p>The first experiment examined the effect of ETY on the growth performance, nutrient digestibility, immune response, and gut health of weanling pigs. A total of 192 weanling pigs (6.0 ± 1.04 kg) were allocated to 4 corn, soybean-based diets with increasing concentrations of ETY (0, 1, 2, or 4 g/kg) for a 43-d trial. There were 8 replicate pens (4 replicate pens per sex) and 6 pigs per replicate for each dietary treatment. The experiment was set up as a randomized complete block design. Dietary ETY supplementation did not affect the growth performance of weanling pigs. The ATTD of neutral detergent fiber (NDF) linearly increased (P < 0.05) at d 28. The concentrations of serum antioxidant and antibody markers increased (P < 0.05) from d 14 to d 43; a linear increase (P < 0.05) in catalase was observed on d 14 with increasing ETY supplementation in the diets. The inclusion of ETY in the diet did not affect the mRNA abundance of anti-inflammatory markers in the ileal mucosa of pigs but increased (P < 0.01) glutathione peroxidase 4. Ileal villus height (VH) and villus height to crypt depth (VH:CD) ratio were greater (P < 0.05) in pigs fed ETY supplemented diets relative to control pigs. However, jejunal VH and the VH:CD ratio was not affected by ETY inclusion in the diet. Pigs fed diets with increasing ETY levels had higher (P < 0.05) ileal digesta butyrate concentration relative to control pigs, but not propionate or acetate. </p> <p>The second experiment examined the effect of ETY on the growth performance, nutrient digestibility, and intestinal health of broiler chickens during a coccidia challenge. From d 1 to 14 post hatching, 480 broiler chickens (49.9 ± 3.95 g) were allocated to 3 corn-soybean meal-based diets with increasing concentrations of ETY (0, 1, or 2 g/kg). There were 16 replicate cages and 10 birds per cage. The experiment was designed as a randomized complete block design with body weight (BW) used as a blocking factor. On d 14 post hatching, the birds were combined and re-randomized within each of the 0, 1, or 2 ETY g/kg experimental diets. Following this, the number of birds was reduced to 8 birds per cage with 8 replicate cages. Each of the 3 diet groups was split into a challenge or no-challenge group. This resulted in a 3 × 2 factorial arrangement of treatments with 3 experimental diets and 2 challenge states. The BW ratio before re-randomization was maintained across all treatments during the reallotment. On d 15 post hatching, the birds in the challenge group were orally gavaged with 1 mL solution containing 25,000, 25,000, and 125,000 oocysts of E. maxima, E. tenella, and E. acervulina, respectively. The birds belonging to the no-challenge group were orally gavaged with 1 mL phosphate buffered saline. Data were analyzed using the MIXED procedure of SAS, and polynomial contrasts were used to estimate the linear and quadratic effects of ETY. The coccidia challenge (CC) decreased (P < 0.01) the BW gain, feed intake, and G:F of broiler chickens from d 14 to 21. Increasing supplementation of dietary ETY improved (P < 0.05) the G:F of birds. Also, the CC reduced (P < 0.01) the apparent total tract utilization of dry matter (DM), nitrogen (N) and gross energy (GE). The CC reduced (P < 0.01) the apparent metabolizable energy (AME) and the nitrogen corrected apparent metabolizable energy (AMEn) of diets fed to broiler chickens. On d 21, dietary ETY linearly increased (P < 0.01) the apparent ileal digestibility of DM, N, and GE in broiler chickens. The CC increased (P < 0.01) the mRNA gene expression of TNFα, IL-1β, IL-10, and IL-6. There was a tendency (P < 0.1) for ETY to reduce IL-1β expression in broiler chickens on d 21. Additionally, ETY supplementation increased (P < 0.05) the gene expression of occludin in the ceca of broiler chickens but not claudin 1. Serum catalase increased (P < 0.05) with increasing supplementation of dietary ETY in broiler chickens on d 21. Dietary ETY linearly increased (P < 0.05) the ileal villus height to crypt depth ratio and ileal goblet cell count and density in broiler chickens. The ileal and excreta oocyst counts decreased (P < 0.01) with increasing supplementation of dietary ETY in coccidia-challenged broiler chickens on d 21. </p> <p>In summary, ETY inclusion in diets of weanling pigs partially reduced reactive oxygen species damage and enhanced intestinal health without negatively affecting growth performance. Hence, ETY could be favorable in attenuating some of the deleterious effects of post-weaning stress in weanling pigs. Dietary ETY also reduced oxidative damage, improved growth performance, enhanced nutrient utilization, and augmented intestinal development in broiler chickens. However, the inclusion of ETY did not mitigate the adverse effects of a coccidia challenge in broiler chickens. Therefore, further studies may be necessary to investigate the prospect of ETY as a dietary strategy for combating coccidiosis.</p> <p><br></p>

O objetivo desta pesquisa foi avaliar o comportamento térmico de diferentes linhagens de frangos de corte submetidas a estresse e conforto durante o ciclo de produção. Para isso, realizou-se um experimento em câmara climática, durante as seis semanas do ciclo de criação, em que os animais foram submetidos a duas condições ambientais: conforto e estresse. Foram adotados quatro tratamentos, sendo assim definidos: tratamento C60 (condição de conforto), com 60 minutos de exposição; tratamento E30, tratamento E60 e tratamento E90 (condição de estresse), com 30, 60 e 90 minutos de exposição, respectivamente. O delineamento experimental adotado foi o de quadrados latinos 4 x 4, sendo caracterizados por quatro lotes de aves, expostas aos quatro tratamentos, nos quatro primeiros dias de cada semana. As aves, das linhagens Avian e Cobb, foram divididas em lotes de 48 aves por semana, totalizando 96 animais, e totalizando 586 aves, de ambos os sexos, durante todo o período experimental. As variáveis climáticas adotadas para as condições de conforto e estresse diferiram ao longo das semanas, uma vez que as necessidades térmicas de frangos de corte diferem com o decorrer do ciclo produtivo. No primeiro capítulo, as variáveis fisiológicas, frequência respiratória e temperatura cloacal foram estudadas, estipulando-se, dessa maneira, faixas para as condições de conforto e estresse. Com base nessas variáveis, estudou-se a tolerância das linhagens ao estresse térmico, e observou-se que a linhagem Cobb é mais tolerante ao estresse térmico. No segundo capítulo, estudou-se a influência de tempo de exposição sobre a temperatura superficial das seguintes regiões corporais: asa, cabeça, pata, dorso e crista. O tempo de exposição não influenciou, em nenhuma das semanas, a temperatura superficial das aves, havendo diferenças significativas apenas entre a condição de conforto e estresse. Baseando-se nessas informações, e nessas regiões corporais, determinaram-se modelos de regressão linear múltipla para cada uma das semanas do ciclo de criação, para ambas as linhagens, sendo denominadas por TSM Nascimento. A escolha dos modelos foi realizada pelo método da máxima verossimilhança, pelo critério de Akaike (AIC) e pelo teste qui-quadrado para verificar o número de regiões corporais incluídas em cada um dos distintos modelos. No terceiro capítulo, efetuou-se o balanço de calor sensível e latente das aves, baseado nos modelos de temperatura superficial TSM Nascimento, na temperatura do núcleo corporal (adotada na pesquisa como a temperatura cloacal) e nas variáveis ambientais coletadas durante a pesquisa, para ambas as linhagens. Observou-se que, em condição de conforto, a partir da terceira semana, as trocas sensíveis correspondem a até 80% do total das trocas de calor. Em estresse térmico, as trocas latentes correspondem a até 84% do total. Verificou-se que as aves são mais susceptíveis ao estresse térmico na terceira semana do ciclo produtivo. / The aim of this research was to evaluate thermal behaviour of different broiler chicken strains submitted to stress and comfort through lifecycle. Thereunto, an experiment was accomplished in climatic chamber, during the six weeks of life of the birds, with the animals submitted to two environmental conditions: comfort and stress. Four treatments were adopted, defined as: treatment C60 (comfort condition), with 60 minutes of exposure; treatment E30, treatment E60 and treatment E90 (stress condition), with 30, 60 and 90 minutes of exposure, respectively. Experimental design adopted was a 4 x 4 latin square, characterized by four lots of birds, exposed to the four treatments, in the first four days of each week. Broiler, from Avian and Cobb strains, were divided in lots of 48 birds per week, totalizing 96 animals, and totalizing 586 animals, both sexes, during all experimental period. Climatic variables adopted to comfort and stress conditions differd through the weeks, once that thermal requirements of broiler chickens differ throughout growing cycle. In the first chapter, physiological variables respiration rate and cloacal temperature were studied, stipulating in this way, bands to comfort and stress conditions. Based on these variables, the tolerance of strains to thermal stress was studied, and was observed that Cobb strain is more tolerant to heat stress. In the second chapter, the influence of exposure time on superficial temperature was studied in the following body regions: wing, head, feet, back and comb. Exposure time did not influence, in none of weeks, superficial temperature of birds, with significative differences only among comfort and stress conditions. Based on these boards, and on these body regions, multiple linear regression models were determined to each week of lifecycle, to both strains, being named as TSM Nascimento. The selection of the models was done by maximum likelihood method, by Akaikes criteria (AIC) and by qui-square test to verify the number of body regions included in each one of the models. In the third chapter, was accomplished sensible and latent heat balance of the birds, based on superficial temperature models TSM Nascimento, core body temperature (adopted in the research as cloacal temperature) and on environmental variables collected during the research, to both strains. It was observed that in comfort condition, from third week of lifecycle and on, sensible exchanges corresponded for up to 80% of the total exchanges. In thermal stress, latent exchanges corresponded for up to 84% of the total. It was verified that broiler chickens are more susceptible to thermal stress in the third week of lifecycle.

Submitted by (edna.saturno@ufrpe.br) on 2017-03-22T12:24:42Z No. of bitstreams: 1 Ana Paula da Silva Ferreira Santos.pdf: 254127 bytes, checksum: f61bc4123a4a165a0b7cc4f2fc276b83 (MD5) / Made available in DSpace on 2017-03-22T12:24:42Z (GMT). No. of bitstreams: 1 Ana Paula da Silva Ferreira Santos.pdf: 254127 bytes, checksum: f61bc4123a4a165a0b7cc4f2fc276b83 (MD5) Previous issue date: 2006-02-23 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The objective of this study was to evaluate the effect of substitution of soybean meal protein by cottonseed meal protein (FA) on the performance of broiler chickens. The treatments consisted of a reference diet containing corn and soy meal and four experimental diets, substituting 10%, 20%, 30% and 40% of soybean meal crude protein of reference diet. The results obtained were analyzed through the SAS mixed procedure. The performance results had been correlatedwith the diets cost for bioeconomic analysis. The study showed that until the level of 40% of substitution did not have significant effect on the weight gain (GP) and feed intake (CR). However, linear increase in the feed conversion have occurred (CA). The rentability presented negative linear effect for diets containing cottonseed meal. The zootechnical performance of the broilers was not wronged, however the feed conversion reduced the yield of the production. / Este estudo objetivou avaliar o efeito da substituição da proteína do farelo de soja pela proteína do farelo de algodão (FA) sobre o desempenho de frangos de corte.Os tratamentos consistiram de uma ração referência à base de milho e farelo de soja e quatro dietas experimentais, substituindo 10%, 20%, 30% e 40% da proteína bruta do farelo de soja da ração referência. Os resultados obtidos foram analisados pelo mixed procedure do SAS. Os resultados de desempenho foram correlacionados com custo das dietas para análise bioeconômica. O estudo mostrou que até o nível de 40% de substituição não houve efeito significativo sobre o ganho de peso (GP) e consumo de ração (CR). Entretanto, ocorreu aumento linear na conversão alimentar (CA). A rentabilidade apresentou efeito linear negativo para dietas contendo farelo de algodão. O desempenho zootécnico das aves não foi prejudicado, contudo a conversão alimentar reduziu a rentabilidade da produção.

O objetivo desta pesquisa foi avaliar o comportamento térmico de diferentes linhagens de frangos de corte submetidas a estresse e conforto durante o ciclo de produção. Para isso, realizou-se um experimento em câmara climática, durante as seis semanas do ciclo de criação, em que os animais foram submetidos a duas condições ambientais: conforto e estresse. Foram adotados quatro tratamentos, sendo assim definidos: tratamento C60 (condição de conforto), com 60 minutos de exposição; tratamento E30, tratamento E60 e tratamento E90 (condição de estresse), com 30, 60 e 90 minutos de exposição, respectivamente. O delineamento experimental adotado foi o de quadrados latinos 4 x 4, sendo caracterizados por quatro lotes de aves, expostas aos quatro tratamentos, nos quatro primeiros dias de cada semana. As aves, das linhagens Avian e Cobb, foram divididas em lotes de 48 aves por semana, totalizando 96 animais, e totalizando 586 aves, de ambos os sexos, durante todo o período experimental. As variáveis climáticas adotadas para as condições de conforto e estresse diferiram ao longo das semanas, uma vez que as necessidades térmicas de frangos de corte diferem com o decorrer do ciclo produtivo. No primeiro capítulo, as variáveis fisiológicas, frequência respiratória e temperatura cloacal foram estudadas, estipulando-se, dessa maneira, faixas para as condições de conforto e estresse. Com base nessas variáveis, estudou-se a tolerância das linhagens ao estresse térmico, e observou-se que a linhagem Cobb é mais tolerante ao estresse térmico. No segundo capítulo, estudou-se a influência de tempo de exposição sobre a temperatura superficial das seguintes regiões corporais: asa, cabeça, pata, dorso e crista. O tempo de exposição não influenciou, em nenhuma das semanas, a temperatura superficial das aves, havendo diferenças significativas apenas entre a condição de conforto e estresse. Baseando-se nessas informações, e nessas regiões corporais, determinaram-se modelos de regressão linear múltipla para cada uma das semanas do ciclo de criação, para ambas as linhagens, sendo denominadas por TSM Nascimento. A escolha dos modelos foi realizada pelo método da máxima verossimilhança, pelo critério de Akaike (AIC) e pelo teste qui-quadrado para verificar o número de regiões corporais incluídas em cada um dos distintos modelos. No terceiro capítulo, efetuou-se o balanço de calor sensível e latente das aves, baseado nos modelos de temperatura superficial TSM Nascimento, na temperatura do núcleo corporal (adotada na pesquisa como a temperatura cloacal) e nas variáveis ambientais coletadas durante a pesquisa, para ambas as linhagens. Observou-se que, em condição de conforto, a partir da terceira semana, as trocas sensíveis correspondem a até 80% do total das trocas de calor. Em estresse térmico, as trocas latentes correspondem a até 84% do total. Verificou-se que as aves são mais susceptíveis ao estresse térmico na terceira semana do ciclo produtivo. / The aim of this research was to evaluate thermal behaviour of different broiler chicken strains submitted to stress and comfort through lifecycle. Thereunto, an experiment was accomplished in climatic chamber, during the six weeks of life of the birds, with the animals submitted to two environmental conditions: comfort and stress. Four treatments were adopted, defined as: treatment C60 (comfort condition), with 60 minutes of exposure; treatment E30, treatment E60 and treatment E90 (stress condition), with 30, 60 and 90 minutes of exposure, respectively. Experimental design adopted was a 4 x 4 latin square, characterized by four lots of birds, exposed to the four treatments, in the first four days of each week. Broiler, from Avian and Cobb strains, were divided in lots of 48 birds per week, totalizing 96 animals, and totalizing 586 animals, both sexes, during all experimental period. Climatic variables adopted to comfort and stress conditions differd through the weeks, once that thermal requirements of broiler chickens differ throughout growing cycle. In the first chapter, physiological variables respiration rate and cloacal temperature were studied, stipulating in this way, bands to comfort and stress conditions. Based on these variables, the tolerance of strains to thermal stress was studied, and was observed that Cobb strain is more tolerant to heat stress. In the second chapter, the influence of exposure time on superficial temperature was studied in the following body regions: wing, head, feet, back and comb. Exposure time did not influence, in none of weeks, superficial temperature of birds, with significative differences only among comfort and stress conditions. Based on these boards, and on these body regions, multiple linear regression models were determined to each week of lifecycle, to both strains, being named as TSM Nascimento. The selection of the models was done by maximum likelihood method, by Akaikes criteria (AIC) and by qui-square test to verify the number of body regions included in each one of the models. In the third chapter, was accomplished sensible and latent heat balance of the birds, based on superficial temperature models TSM Nascimento, core body temperature (adopted in the research as cloacal temperature) and on environmental variables collected during the research, to both strains. It was observed that in comfort condition, from third week of lifecycle and on, sensible exchanges corresponded for up to 80% of the total exchanges. In thermal stress, latent exchanges corresponded for up to 84% of the total. It was verified that broiler chickens are more susceptible to thermal stress in the third week of lifecycle.

Thesis (M. Sc. Agriculture (Animal Production)) -- University of Limpopo, 2018 / Two experiments were conducted to determine the effect of replacing maize meal with a low tannin sorghum meal (Macia) on productivity, gut morphology, carcass characteristics and bone morphometrics of Ross 308 broiler chickens aged one to 42 days. In each experiment, a total of 160 Ross 308 broiler chickens were assigned to a complete randomized design with 5 treatments, replicated 4 times with 8 chickens per replicate. Five diets were formulated to contain sorghum replacement levels at 0, 25, 50, 75 and 100% to meet the nutrient requirements of Ross 308 broiler chickens. Data was analysed using statistical analysis of variance. The first experiment determined the effect of replacing maize meal with a low tannin white sorghum meal on productivity and gut morphology of unsexed Ross 308 broiler chickens aged 1 to 21 days. Feed intake, growth rate, feed conversion ratio, live weight, N-retention, caecum and large intestine digesta pH, large intestine lengths, crop, gizzard, caecum and large intestine weights, gut intestinal villi height, crypt depth and villi height to crypt depth ratio of unsexed Ross 308 broiler chickens were not affected (P>0.05) by the treatment effects. However, replacement of maize meal with sorghum meal improved (P<0.05) metabolisable energy intake and small intestine digesta pH values. It was concluded that maize meal can be replaced by a low tannin white sorghum meal in the diet without adverse effects on unsexed Ross 308 broiler chickens aged one to 21 days. The second experiment determined the effect of replacing maize meal with sorghum meal on productivity, gut morphology, carcass characteristics and bone morphometrics of Ross 308 male broiler chickens aged 22 to 42 days. Replacing maize meal with sorghum meal had no effect (P>0.05) on feed intake, feed conversion ratio (FCR), live weight and nitrogen retention (N-retention) of male Ross 308 broiler chickens aged 22 to 42 days. Replacing maize meal with sorghum meal improved (P<0.05) ME intake and growth rate of the chickens. Caecum and large intestine digesta pH, GIT, caecum and large intestine lengths, small intestine, caecum and large intestine weights, gut intestinal villi height, crypt depth and villi height to crypt depth ratio, drumstick, thigh and wing weights, drumstick, thigh and wing colour, meat sensory evaluation, meat pH and bone morphometrics of male Ross 308 broiler chickens were not affected (P>0.05) by replacement of maize meal with sorghum vii meal. It was concluded that maize meal can be replaced by a low tannin white sorghum meal at 25, 50, 75 and 100% levels without causing adverse effects on productivity and carcass characteristics of male broiler chickens aged 22 to 42 days. Key words: Low tannin sorghum meal, Maize meal, Broiler chickens, Growth rate, Carcass characteristics. / National Research Foundation (NRF)

The high cost of feed materials and feed additives in developing nations has elicited interest in the search for sustainable alternatives. Moringa (Moringa oleifera), one of such sustainable alternatives is a tropical plant that has its usefulness investigated in this study. A 42-day study was designed to determine the response of Ross 308 broilers to dietary Moringa oleifera leaf meal supplementation. The Moringa oleifera leaves used for the study were analysed for proximate, mineral and composition as well as phytochemical contents before being incorporated in the diet. Day-old Ross 308 broiler chicks (n = 500) were allotted to five treatments in completely randomized design with each treatment replicated five times and each replicate having 20 chicks. The birds were subjected to diets supplemented with Moringa oleifera leaf meal at 0, 25, 50, 75 and 100 g/kg feed at both starter and finisher stage, respectively and designated as T1, T2, T3, T4 and T5. Moringa oleifera leaf meal level that supported optimum production and physiological variables was modelled using the quadratic function. At day 42, three birds per replicate were slaughtered to evaluate carcass and organ yields. Result of the proximate composition revealed that MOLM is rich in protein (32.37%) and neutral detergent fibre (52.16%). Mineral assay indicated that MOLM was high in calcium, sodium, potassium, sulphur and iron. Daily feed intake (FI), average daily gain (ADG) and feed conversion ratio were the same among the treatments with the exception of starter broilers on diet T1 that had higher ADG (p<0.05) than those on the other diets. Final live weight (FLW), mortality and gizzard weight were influenced (p<0.05) by Moringa oleifera leaf meal supplementation. Moringa oleifera leaf meal supplementation had no effect on parameters measured. Moringa oleifera leaf meal supplementation at 39.98 and 35.80 g/kg feed supported optimum FLW and ADG at starter phase and 46.88 g/kg feed MOLM supported optimum FLW at finisher phase. In conclusion, Moringa oleifera leaf meal is a good source of nutrients and suitable for production of enhanced cut parts in broiler chickens. Birds on 50 and 75 g Moringa oleifera leaf meal/kg feed had higher (p<0.05) packed cell volume (PCV), red blood cell (RBC) and glucose than those on the other 3 treatment diets. The white blood cell (WBC) counts for birds on 50 g Moringa oleifera leaf meal/kg feed were higher (p<0.05) than those on 100 g Moringa oleifera leaf meal/kg feed but similar (p>0.05) to those on 0, 25 and 75 g MOLM/kg feed. Blood platelet count maintained the trend 75 g > 0 g > 50 g > 100 g > 25 g MOLM/kg feed with birds on 75 g Moringa oleifera leaf meal/kg feed being statistically higher (p<0.05) than those on 25, 50 and 100 g MOLM/kg feed. Dietary Moringa oleifera leaf meal supplementation had no significant effect (p>0.05) on haemoglobin (Hb), total serum protein (TSP), albumin, cholesterol and uric acid. Triglyceride (TG) level of birds on 25, 75 and 100 g Moringa oleifera leaf meal/kg feed decreased significantly compared to those on 0 and 50 g MOLM/kg feed. Daily Moringa oleifera leaf meal supplementation had a significant effect (p<0.05) on the differential WBC count. Daily Moringa oleifera leaf meal supplementation with 26.99 g/kg feed and 31.95 g/kg feed respectively supported optimum PCV (38.62%) and glucose (245.42 mg/dl) in Ross 308 broilers. It is, therefore summarized that optimizing MOLM supplementation level in the ration of Ross 308 broilers could assist in improving their productivity. / Agriculture and  Animal Health / Ph. D. (Agriculture)

The first aim of this research was to determine the prevalence of IBV in broilers within the Canterbury province, New Zealand, in late winter and to search for associations with management or environmental factors. The second aim was to study how ambient stressors affect the immune system in birds, their adaptive capacity to respond, and the price that they have to pay in order to return to homeostasis. In a case control study, binary logistic regression analyses were used to seek associations between the presence of IBV in broilers and various risk factors that had been linked in other studies to the presence of different avian pathogens: ambient ammonia, oxygen, carbon dioxide, humidity and litter humidity. Pairs of sheds were selected from ten large broiler farms in Canterbury. One shed (case) from each pair contained poultry that had a production or health alteration that suggested the presence of IBV and the other was a control shed. Overall, IBV was detected by RT-PCR in 50% of the farms. In 2 of the 5 positive farms (but none of the control sheds) where IBV was detected there were accompanying clinical signs that suggested infectious bronchitis (IB). Ambient humidity was the only risk factor that showed an association (inverse) with the prevalence of IBV (p = 0.05; OR = 0.92). It was concluded within the constraints of the totally enclosed management systems described, that humidity had an influence on the presence of IBV, but temperature, ammonia, carbon dioxide, oxygen or litter humidity had no effect. In another study environmental temperatures were changed in order to affect the biological function and adaptive capacity of chickens following infection with IBV. The 'affective states' of the animal were assessed by measuring levels of corticosterone (CORT) in plasma and tonic immobility (TI). It was found that low (10 +/- 2°C) and high (30 +/- 2°C) temperatures exacerbated the respiratory signs and lesions in birds infected with IBV as compared to those housed at moderate (20 +/- 2°C) temperatures. The chickens housed at high temperatures showed significantly decreased growth, a higher proportion of hepatic lesions (principally haemorrhages) and a longer tonic immobility period, but there was no significant alteration in the plasma levels of CORT. The birds housed at low temperatures developed a higher proportion of heart lesions (hydropericardium, ventricular hypertrophy) and had significantly higher levels of plasma CORT than birds housed under moderate and/or high temperatures. The specific antibody response to IBV decreased in birds housed under high temperatures. Interestingly the birds housed at high temperatures developed significantly higher levels of haemagglutinin antibodies to sheep red blood cells (SRBC) than those birds housed under low or moderated temperatures. Cell mediated immunity was not significantly affected by heat or cold stress in the first 13 days of treatment but at 20 days the levels of interferon gamma in the birds subjected to low temperatures were lower than in the high temperature group. In other trials, the exogenous administration of low physiological doses of oral CORT (as compared to high pharmacological doses typically used in such experiments) to birds resulted in suppression or enhancement of the immune response depending on duration of treatment and/or dose and nature of the antigen. To our knowledge, this is the first study to show that exogenous CORT can produce an enhancement in the immune response in chickens. iv In conclusion, environmental stressors such as high or low temperatures do affect the physiology of the fast-growing broiler. The adjustments the birds have to make to maintain homeostasis impacts on the course of common infectious diseases, such as IB, that normally is mild in the New Zealand poultry industry. The administration of exogenous CORT showed that this hormone may be part of the physiological stress response and acts as a messenger to prepare the immune system for potential challenges (e.g., infection).

Recently rapeseed products have become more important for animals nutrition and poultry feeding. Such nutrition matters like glucosinolates, tannins, nonstarch polysacharides limit its bigger interposition. The quality of rapeseed products and seeds is changeable, because it depends on genotype of the rapeseed, fertilization conditions and their technological processing during the time of feed preparation. The aim of this work is to investigate the nutritional value of rapeseed products, estimate the influence of rapeseeds to the intensity of broiler chickens growth, consumption and digestibility of nutrients. To determine the effect of phytates ferment preparation supplement to calcium and phosphorus utilization in the organism of broiler chickens and the effect of possible rapeseed supplement in feed for broiler chickens femorals’ sensory quality.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2007. / Härtill 6 uppsatser.