Master of Science / Department of Agricultural Economics / Vincent R. Amanor-Boadu / This study assessed the farm and farmer characteristics influencing the profitability of broiler chicken farms in Ghana. It used data obtained from the 2015 census of the poultry industry conducted by USAID-METSS in collaboration with Ghana's Ministry of Food and Agriculture and the Ghana National Association of Poultry Farmers. Results show that broiler production in Ghana is operated on a small scale basis with an average number of 1,410 birds. Broiler chicken production is profitable in Ghana with national average gross margin/bird of GHS 9.22 and standard deviation of 8.40. Regression analysis was carried out using Ordinary Least Square method to estimate the effect of farm and farmer characteristics on profitability and also explore regional differences. Results shows that farm income and feed were negative and statistically significant such that a farmer with primary income from broiler chicken production had a decrease in gross margin of GHS 1.24 per bird compared to a farmer with other sources of income; a farmer that increases one unit of own feed production will have a decrease in gross margin of GHS 0.06 per bird. Additionally, regional differences exist such that farms situated in Ashanti, Central, and Eastern had higher gross margin per bird of GHS 3.21, GHS 6.10 and GHS 6.26 respectively compared to farms situated in Brong Ahafo Region. In conclusion, the study shows that both farmer (primary source of income) and farm characteristics (such as regional location and the extent to which feed was prepared on the farm) were important in explaining broiler chicken profitability. Finally, continuous research is recommended to examine the robustness of these factors in explaining profitability.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / More contaminated areas with copper were discovered and this had contributed negatively for plants establishment, so more studies are need to reutilize this areas. Thus, the objective of this work is to enable the attenuation of the contamination on native woody seedlings production in contaminated soil with copper. Three experiments were realized. The first involving the evaluation of the growth and quality of Bauhinia forficata Link, Pterogyne nitens Tul and Enterolobium contortisiliquum Vell. seedlings in soil with dosis of copper. On the second work, the effect of broiler litter was evaluated on soil chemical attributes and the growth of E. contortisiliquum seedling. On the third, the effect of broiler litter (CA) and mix of broiler litter with commercial substrate (CA+SC) evaluated to attenuation of copper contamination in soil and E. contortisiliquum potential to descontamination the soil. E. contortisiliquum had more tolerance to high copper dosis than B. forficate and P. nitens. The addition of 36% of CA on the SC and 33% on the peat enables increasing on morphological parameters of E. contortisiliquum seedlings. The utilization of the CA+SC was efficient to attenuation of the copper contamination. The morphological parameters was stimulated by the addition of the mix, with better results in 20 and 30% in contaminated soil with 400 mg of kg-1 of soil. / Tem sido evidenciado um aumento em áreas contaminadas com cobre e este fato tem contribuído negativamente para o estabelecimento de plantas, sendo necessários estudos de alternativas para reutilização destas áreas. Diante disso, o objetivo desse trabalho foi possibilitar o uso de amenizantes de contaminação na produção de mudas de espécies nativas em solo contaminado com cobre. Para atender o objetivo foram realizados três experimentos. O primeiro envolveu a avaliação da interferência de doses crescentes de cobre aplicado ao solo no crescimento e na qualidade de mudas de Bauhinia forficata Link(pata de vaca), Pterogyne nitens Tul (carne de vaca) e Enterolobium contortisiliquum Vell. (timbaúva) No segundo experimento avaliou-se o efeito de proporções de cama de aves nos atributos químicos do solo e morfológicos de crescimento de mudas de timbaúva e o terceiro experimento avaliou-se o efeito da cama de aviário e a mistura de cama de aviário com substrato comercial como amenizante de cobre no solo e o potencial de Enterolobium contortisiliquum para descontaminação. As mudas de timbaúva toleram maiores doses de cobre no solo em relação à pata de vaca e carne de vaca. A adição de aproximadamente 36% de cama de aviário ao substrato comercial e de 33% à turfa possibilita aumento nos parâmetros morfológicos de mudas de timbaúva. A utilização cama de aviário + substrato comercial foi eficiente como amenizante da contaminação do solo com cobre. Os parâmetros morfológicos, foram estimulados com a adição de cama de aviário + substrato comercial, obtendo os melhores resultados com a dição de 20 a 30 % em solo contaminado com 400 mg de Cu Kg -1 de solo.

The incidence of ascites in slaughterhouses inspected by the Brazilian Agricultural Authority resulted in the condemnation of 1,605,439 broiler carcasses in the state of Rio Grande do Sul between 2002 and 2006. This figure corresponds to 8.19% of the number of total carcass condemnations in the period according to data of the Brazilian Department of Agriculture. This study aimed to discuss the causes and mechanism of control of ascites and assess the evolution of this metabolic disorder, which accounted for 6.4% of total carcass condemnations in 2002, a figure that rose to 9.6% in 2006. Linear regression showed a strong correlation (0.92), demonstrating that ascites-related condemnations are increasing. The financial losses resulting from these condemnations in that period amount to R$ 3,6 milion or US$1,7 milion , which highlights the importance of implementing more effective control and monitoring of this condition in the poultry sector. / A ocorrência de condenação total de carcaças de frangos devido à síndrome ascítica (SA) em matadouros sob Inspeção Federal no estado do Rio Grande do Sul alcançou a soma de 1.605.439 unidades no período compreendido entre 2002 e 2006, chegando a 8,19% do total de condenações, sem aproveitamento parcial, do período, conforme dados obtidos junto ao MAPA (Ministério da Agricultura Pecuária e Abastecimento). Este trabalho teve como objetivos, discutir e apresentar as causas e formas de controle da SA, bem como avaliar a evolução da ocorrência deste transtorno metabólico, uma vez que, em 2002 a síndrome ascítica representou 6,4% do total de condenações, crescendo gradativamente até 2006, onde a ascite representou, até o mês de novembro, 9,6% das condenações de carcaça total. A regressão linear apresentou uma forte correlação (0.92) demonstrando que os casos de condenações por ascite estão aumentando gradualmente. Os prejuízos advindos destas condenações, durante o período avaliado, geram valores na ordem de R$ 3,6 milhões, o equivalente a US$ 1,7 milhões, demonstrando com isso, a importância de maior controle e monitoramento da enfermidade para o setor avícola.

The microbial populations in the gastrointestinal tracts of poultry play an important role in normal digestive processes and in maintaining animal health. The purpose of this study was to evaluate the effects of probiotics, prebiotics and synbiotics on the growth parameters, gut ecosystem, histology and immune function. In this study, four experiments one in vitro and three in vivo were conducted using specific pathogen free (SPF) and Hubbard broiler chickens. The first experiment was designed to determine the influence of inulin as an effective prebiotic on lactic acid bacteria (LAB) strains, and to screen LAB for selection as a source of chicken probiotic. Eight strains of LAB were isolated from chicken caeca and three strains from the Plymouth University culture collection were screened for potential probiotic properties for growth in inulin from Jerusalem artichoke (Helianthus tuberosus) and commercial inulin (Frutafit® HD, Netherlands). Lactobacillus animalis JCM 8692 strain isolated from chicken caeca showed the highest auto-aggregation and co-aggregation ability, resistance to acidity and bile salts, strong suppression of pathogens and ability to adhere to epithelial cells compared with other isolated strains. The second experiment was conducted to investigate the influence of commercial inulin and Jerusalem artichoke tubers as prebiotic supplementation on the diversity of the caecal microflora, jejunum histology and immune organ of SPF chickens. This investigation has found that inulin which was extracted from JA had a similar result when compared with commercial inulin and could be a suitable candidate for an inulin source in broiler diets. The third experiment was conducted to investigate the influence of Bactocell® (PRO1) and Lb. animalis (PRO2) as probiotic supplements on broiler chickens. EPEF was significantly increased in probiotic1 and probiotic2 compared with control (311.03, 309.87 and 260.06) respectively. Both types of probiotics supported the growth of chicks healthy and could be a suitable candidate as a source of probiotic in broiler diet. The fourth experiment was conducted to investigate the influence of dietary supplementation of a probiotic (Lb. animalis), a prebiotic JA tuber and a combination of both (Synbiotic) in broiler chickens. Growth performance was improved in all additive supplementation compared with the control group. EPEF was increased in probiotic, prebiotic and synbiotic compared with control (290.8±11.8, 300.9±3.86, 322.1±7.09 and 262.3±5.94) respectively. Beneficial bacteria in the guts of chicks fed probiotic, prebiotic and synbiotic was increased compared with chicks fed control diet. The diversity of microbial population in the gastrointestinal tract of chickens improved due to additives. The intestinal villus lengths and microvilli density was improved in all additives supplementation in comparison with control. Overall, it was concluded that probiotic, prebiotic and synbiotics can positively affect production performance and can improve the gut health.

Dans un contexte où la demande mondiale en viande de poulet ne cesse d’augmenter, les qualités technologique et sensorielle de cette viande sont devenues un enjeu majeur pour l’industrie. L’analyse de deux lignées de poulet divergentes pour le pH ultime (pHu) du filet confirme que la génétique est un déterminant majeur de ce caractère. Leur comparaison montre qu’augmenter le pHu du filet par sélection impacte le pHu d’autres muscles et améliore de nombreux critères dont le pouvoir de rétention d’eau, le rendement technologique et la tendreté de la viande. Si l’histologie et la composition biochimique du muscle ne sont pas affectées par la sélection, nos résultats suggèrent un lien défavorable entre un trop faible niveau des réserves énergétiques musculaires et l’incidence de défauts structuraux telle que les striations blanches. Par contre, aucun antagonisme génétique entre le pH ultime et les caractères de production (poids vif, rendement en viande et indice de consommation) n’a été observé. / In a context where the global demand for chicken meat is increasing, technological and sensory qualities of this meat have become a major issue for the poultry industry. The analysis of two chicken lines divergent for ultimate pH (pHu) of breast fillets confirms that genetics is a major determinant of this trait. Between-lines comparison shows that increasing the pHu by selection changes the pHu of other muscles and improves many other quality criteria such as water-holding capacity, curing-cooking yield and meat tenderness. Although histology and biochemical composition of the muscle are not affected by the selection, our results suggest an unfavorable relationship between low muscle energy reserve and the incidence of structural defects such as white striping. On the contrary, no negative association between ultimate pH and production traits (body weight, meat yield and feed conversion ratio) was observed.

The role-players in the South African (SA) agricultural sector have in recent years been increasingly exposed to international agricultural markets and this can have an important impact on them because (1) they are generally price-takers in world markets and (2) the rate of change in agriculture, and the uncertainty arising from it, appears to be accelerating in the global context (Boehlje, et. al., 2001). Therefore, it is critical that role players in the SA agricultural sector, including agribusinesses, farmers and government, are able to anticipate future directions of world markets (Meyer, 2002). A system of econometric models that could be used for scenario planning and improving business strategy and policy development would facilitate this. A relatively large-scale, multi-sector commodity level econometric simulation model, based on a method of econometric modelling developed and is successfully used by the Food and Agricultural Policy Research Institute (FAPRI) at the University of Missouri, has been developed to describe various agricultural subsectors in South Africa (Meyer, 2006). It is currently housed at the Bureau for Food and Agricultural Policy (BFAP) at the University of Pretoria. The model has a total of 126 equations representing eight crops, five livestock and five dairy commodities, as well as wine, sugar, potatoes and lastly biofuels, which together are referred to as the BFAP Sector Model. The BFAP Sector Model is frequently used for generating baseline projections and conducting a wide range of scenario analysis. The original or Old Broiler Model, which forms part of the BFAP Sector Model, was constructed in 2003 when the first version of the BFAP Sector Model was developed. Over the past view years there have been a number of occasions where the stability of the broiler model seemed to be questionable, especially when more “drastic scenarios”, for example the impact of Avian Influence on the South African broiler industry, were analysed. The original version of the broiler model was not statistically estimated but synthetically constructed, mainly based on sound micro and macro economic principles and theory. The main objective of this dissertation is, therefore, to attempt the construction of an updated broiler model that has improved abilities to generate baseline projections and scenario analysis that capture salient features of the South African broiler market within the BFAP sector modelling framework. The performance of the updated model is compared to the original broiler model to determine whether the new model is performing better. The New Broiler Model is a partial equilibrium model built using new production, consumption, trade and price data as well as a new feed inclusion index. The ordinary least squares (OLS) method was used to estimate the individual equations and their statistical significance was evaluated using typical statistical tests for individual regressions using OLS estimators. These initial tests indicated that the individual equations fit the historical data well, but the per capita consumption and ex abattoir price equations were found to be wanting in terms of their economic significance and especially their ability to generate reliable projections into the future. Consequently the equations were adjusted, thus becoming synthetic equations. The dynamic system structure that resulted from the combination of the individual equations makes it necessary to examine the performance of the overall model when linked to the rest of the BFAP Sector Model. This was done by comparing the results of the Old and New Broiler Models using the baseline projections and performance when dealing with scenario type questions. The elasticities and the results for the scenario analyses indicate that the New Broiler Model is generally less sensitive to changes in exogenous factors than the Old Broiler Model. The change in closure of the model, from making use the price equilibrator approach to an approach where a net import identity is used, is the most significant change that was made to the model and has introduced a lot more stability in the broiler model and also the BFAP Sector Model. Although the enhanced stability is useful within the context of the total BFAP sector model, the sensitivity that is lost in the New Broiler Model could lead to the underestimation of the impacts of exogenous factors on the broiler industry. To summarise, this study was conducted for an industry that is characterised by strong and consistent increasing trends in production and consumption in the presence of a constantly decreasing real broiler price. These strong trends influence any form of statistical estimation procedure that is undertaken. To certain degree one can argue, that the key objective of this study, namely to improve the performance and stability of the broiler model within the BFAP sector model was achieved. However, the advantages over the original broiler model are not as clear as was originally anticipated and there is still substantial work that can be done to improve the model. Most of these potential enhancements do, however, require the buy in of various role-players in the broiler industry together with more detailed data sets than those that are currently available. Copyright / Dissertation (MSc(Agric))--University of Pretoria, 2010. / Agricultural Economics, Extension and Rural Development / unrestricted

Com o aumento, a cada ano, dos alojamentos na cadeia de produção avícola, a disseminação de doenças ficou facilitada. Nos lotes de aves, a fase inicial tem principal importância no que tange à contaminação por Salmonella Enteritidis, devido a maior sensibilidade às infecções pela ausência de uma flora intestinal completa e a imaturidade do sistema imune. Avaliaram-se, neste estudo, os benefícios na progênie do uso de uma vacina inativada em adjuvante oleoso para Salmonella Enteritidis, em matrizes pesadas, através de coleta de ovos bicados e pintos natimortos no incubatório, bem como suabes de arrasto nos aviários de frangos de corte. Observou-se que a imunização das matrizes conferiu uma proteção para suas progênies, tanto em ovos bicados, pintos natimortos coletados no incubatório no dia do nascimento, bem como em granjas de frango de corte, onde foram coletados suabes de arrasto entre 21 e 30 dias. Em ovos bicados foram analisadas 850 amostras, sendo que nos lotes vacinados tiveram 10 amostras (1,18%) positivas, e, nos lotes não vacinados tiveram 288 amostras (33,88%) positivas. Em pintos natimortos foram analisados 850 amostras, sendo os lotes vacinados tiveram 16 amostras (1,88%) positivas e nos lotes não vacinados tiveram 210 amostras positivas (24,70%). Em suabe de arrasto, nas granjas de frangos de corte, foram analisadas 502 amostras para lotes não vacinados; sendo 22 amostras positivas (4,38%). Nos lotes vacinados foram analisados 475 amostras, sendo 6 amostras positivas (1,26%). Os resultados obtidos nos levam a concluir que a vacina de Salmonella Enteritidis inativada em adjuvante oleoso, propicia uma imunidade passiva para as progênies das matrizes de corte que foram vacinadas, proporcionando uma redução significativa a infecções precoces pela bactéria. / With the increase of households in the poultry production chain each year, the spread of diseases was facilitated. In lots of birds, the initial phase has primary importance regarding to contamination by Salmonella Enteritidis, due to a bigger sensitivity to the infections by the absence of a complete gut and the immaturity of the immune system. In this study it was evaluated, the benefits of using the progeny of an inactivated vaccine in oil adjuvant for Salmonella Enteritidis in the main weighted broilers, through collection of eggs pecked and hatchery stillbirth chicks, as well as drag swabs on poultry broiler. It was observed that immunization of matrices gave a protection to their progeny, both egg pecked, hatchery stillborn chicks collected on the day of birth, and in broiler farms, where the drag swabs were collected between 21 and 30 days. In pecked eggs were analyzed 850 samples, being that in the vaccinated lots 10 samples (1.18%) were positive and in non-vaccinated lots 288 samples (33.88%) were positive. In stillbirths chicks were analyzed 850 samples, and in the vaccinated lots were 16 samples (1.88%) positive and in the unvaccinated lots, 210 were positives samples (24.70%). In the drag swab in broiler farms, 502 samples were analyzed for non-vaccinated lots, with 22 positive samples (4.38%). In the vaccinated lots were analyzed 475 samples and six positive samples (1.26%). The results lead us to conclude that the Salmonella Enteritidis inactivated vaccine in oil adjuvant, provides passive immunity to the progeny of broiler breeder flocks were vaccinated, providing a significant reduction in early infections by bacteria.

Nas últimas décadas, a produção de carne de frango vem se intensificando por expressivos avanços tecnológicos. Nutricionalmente, os promotores de crescimento antimicrobianos (antibióticos e quimioterápicos) foram essenciais, beneficiando o desempenho e a eficiência alimentar, quando utilizados como aditivos nas dietas, em doses subterapêuticas. Apesar da comprovada contribuição no desempenho das aves, os antibióticos promotores de crescimento passaram a ser vistos como fatores de risco para a saúde humana, devido ao potencial desenvolvimento da resistência bacteriana cruzada em humanos. Recentemente, têm sido desenvolvidas diversas alternativas aos antibióticos promotores de crescimento, incluindo probióticos, prebióticos, ácidos orgânicos, enzimas e extratos vegetais. Seguindo essa tendência, este estudo teve o objetivo de avaliar a eficácia do uso de extratos vegetais como alternativas aos antimicrobianos promotores de crescimento em dietas de frangos de corte. Foram realizados dois experimentos com frangos de corte para avaliar os efeitos de diferentes extratos vegetais no desempenho, na energia metabolizável da dieta e na morfometria dos órgãos. O experimento de desempenho envolveu 1200 frangos de corte machos criados em galpão experimental no período de 1 a 42 dias de idade, separados em grupos de 40 aves por boxe. O delineamento experimental foi em blocos casualizados, sendo seis tratamentos e cinco repetições. O ensaio de metabolismo contou com 96 frangos machos em crescimento alojados em gaiolas metabólicas para coleta total de excretas, foram seis tratamentos e quatro repetições em delineamento interiramente casualizado. Ambos os experimentos receberam os mesmos tratamentos: dieta controle (DC); DC + 10 ppm de Avilamicina; DC + 1000 ppm de extrato de orégano; DC + 1000 ppm de extrato de cravo; DC + 1000 ppm de extrato de canela e DC + 1000 ppm de extrato de pimenta vermelha. Os produtos à base de extratos vegetais consistiram de microencapsulados contendo 20% do óleo essencial. As variáveis determinadas foram: peso vivo, ganho de peso, consumo de ração, conversão alimentar, mortalidade, energia metabolizável aparente (EMAn) das dietas e peso relativo dos órgãos. Os resultados foram submetidos à análise de variância e as médias comparadas pelo teste de Tukey. Não foi possível observar diferenças significativas (P>0.05) entre os tratamentos propostos para as variáveis de desempenho analisadas em todo o período de criação das aves. Da mesma maneira, a suplementação dos extratos nas dietas não interferiu (P>0.05) nos valores de EMAn das mesmas. A morfometria dos órgãos, em geral, também não foi alterada pela utilização dos extratos vegetais. Pôde ser observado que, os animais que receberam ração controle apresentaram maior peso relativo do fígado em relação aos demais tratamentos, diferindo significativamente (P<0.05) das aves alimentadas com a dieta suplementada com extrato de pimenta, que foi o menor valor observado. / Broiler meat production has experienced expressive technological improvements in the last decades. Nutritionally, the antimicrobial growth promoters (antibiotics and chemotherapeutics) contributed to that, when utilized as feed additives. These antimicrobials are very effective in performance improvement, but there are human health risks associated to their use because of the possibility of development of bacterial cross resistance. In recent years, several alternatives to the antibiotic growth promoters have been proposed including probiotics, prebiotics, organic acids, enzymes and plant extracts. In this context, the objective of the present study was to evaluate the efficacy of plant extracts as alternative growth promoters to the antibiotics as feed additives in chicken diets. Two experiments were conducted to determine the effects of different plant on the metabolizable energy of the diet and performance and organ morphometry of broiler chickens. The performance trial involved 1,200 male chicks raised from 1 to 42 days of age, in groups of 40 birds per pen, in a experimental poultry house. A randomized complete block design, with 6 treatments and 5 blocks, was used. In the metabolism trial, 96 chickens in the grower period were allotted to battery cages and total excreta collection was conducted with 6 treatments and 4 replicates in a completely randomized design. The treatments for both experiments were: Corn-soybean meal control diet (C); C + 10 ppm Avilamycin; C + 1,000 ppm oregano extract; C + 1,000 ppm clove extract; C + 1,000 ppm cinnamon extract; C + 1,000 ppm red pepper extract. The plant extract products added consisted of microencapsulated preparations containing 20% essential oil. The variables evaluated were liveweight, weight gain, feed intake, feed conversion, mortality, apparent metabolizable energy (AMEn) of the diets and organ weights. The results were statistically analyzed by ANOVA and means compared using Tukey&#39;s test. It was not detected any significant (P>0.05) difference among the treatments for the performance variables of the chickens along the growth period. Likewise, the plant extracts supplementation did not affect the AMEn of the diets (P>0.05). Organ morphometry was also, in general, not influenced by the additives. The only significant effect was a higher liver relative weight of the control birds (P<0.05) compared to the red pepper fed birds.

A utilização da enzima fitase nas dietas de não ruminantes permite a quebra da molécula de ácido fítico presente em ingredientes de origem vegetal e disponibilização do fósforo. O objetivo deste trabalho foi avaliar a eficiência de uma fitase bacteriana na liberação de fósforo fítico utilizando curvas de calibração para características ósseas e de desempenho em frangos de corte, e comparar os critérios de resposta quanto a adequação para estimativa da liberação de fósforo, assim como a viabilidade econômica da inclusão da fitase em dietas de frangos de corte. O delineamento experimental adotado foi inteiramente casualisado com 6 tratamentos e 6 repetições no período de 1 a 28 dias de idade. O tratamento controle consistiu de dieta à base de milho e farelo de soja deficiente em fósforo disponível (0,20% e 0,15% de P disponível para as fases de 1 a 21 e 22 a 28 dias, respectivamente). Dois tratamentos corresponderam às dietas basais acrescidas de fósforo inorgânico nos níveis de 0,05% e 0,10%, e os outros três a dieta basal com a inclusão de 66, 99 e 131 FTU/kg de ração. A curva padrão foi construída através do efeito de três níveis de P suplementar consumido sobre variáveis de desempenho e características ósseas. Em seguida, os resultados obtidos com inclusão de fitase foram confrontados com a curva padrão para o cálculo de P liberado pela fitase. O desempenho dos frangos de corte foi prejudicado em função da deficência em P na dieta. Os níveis crescentes de P suplementar influenciaram as variáveis ganho de peso, peso vivo e consumo de ração de forma quadrática, e de forma linear a variável miligramas de cinzas ósseas. A resposta linear é a que melhor descreve a curva padrão, dessa forma, a equação da variável mg de cinzas ósseas foi utilizada para construção da curva. As inclusões de 66, 99 e 131 FTU/kg liberaram, respectivamente, 0,048%, 0,049% e 0,062% de P em dieta à base de milho e farelo de soja. Este estudo demonstra a eficiência da fitase bacteriana em liberar fósforo fítico em dietas com baixos níveis de P, e o benefício econômico da utilização da enzima em dietas de frangos de corte. / Use of the enzyme phytase in the diets of nonruminants allows the hydrolysis of the molecule of phytic acid present in ingredients of plant origin, increasing phosphorus avalilability. The objective of this study was to determine the efficiency of a bacterial phytase to release phytate phosphorus using calibration curves for performance and bone characteristics in broiler chickens, and compare the response criteria for adequacy for estimating the release of phosphorus, as well the economic viability of inclusion of phytase in broiler chickens diets. A completely randomized design with 6 treatments and 6 replicates was used in an experiment with chickens from 1 to 28 days of age. The control treatment was a diet based on corn and soybean meal deficient in availability phosphorus (0,20% and 0,15% available P in the 1 21 and 21 28 days periods, respectively). Two treatmens consisted of the basal diet supplemented with inorganic phosphorus, and the other three treatments received 66, 99 and 131 FTU/kg of feed. The standard curves represented the effect of three levels of additional P intake on performance and bone variables. Then, the responses of the phytase treatments were compared to the standard curves to calculate the P released by phytase. Performance was negatively affected by the P-deficient diets. The increasing levels of supplemental P had quadratic effect on weight gain, live weight and feed intake, and linear effect on mg of bone ash. The linar response is the on that better represents the standard curve, thus the equation of bone ash was elected to estimative the P released. Inclusion of 66, 99 and 131 FTU/kg released 0.048%, 0.049% and 0.062% P from the corn-soy diet. This study demonstrates the efficiency the efficiency of the bacterial phytase to release phosphorus at low levels of inclusion, which may be of economical significance in diets broiler chickens.

O objetivo do trabalho foi avaliar o efeito de diferentes períodos de jejum alimentar (3, 6, 9, 12, 15 e 18 horas) sobre a perda de peso vivo em frangos de corte criados em sistema convencional e o rendimento de carcaça quente e fria (antes e após o resfriamento), além de avaliar os atributos de qualidade da carne de peito de frango. Neste experimento foram utilizados frangos de corte da linhagem Ross com 46 dias de idade. Os resultados encontrados mostraram que o tempo de jejum prolongado teve efeito significativo (p&#8804;0,05) sobre a perda de peso das aves antes do abate, com perda de 5% para um jejum de 12h. Conforme os períodos de jejum aumentavam, também incrementava a quantidade de peso perdido na carcaça viva. Registrou-se um elevado rendimento de carcaça quente com um período entre 3 e 6 horas de jejum e reduzido, a partir de um período de 9 horas acusou uma diferença significativa (p&#8804;0,05). A carcaça fria apresentou uma diminuição no seu rendimento, à medida que aumentou o tempo do jejum, com diferença significativa (p&#8804;0,05), que foi observada a partir de 6 horas de jejum. Os resultados encontrados neste estudo não mostraram que o tempo prolongado da privação de alimentos tenha efeito significativo (p&#8804;0,05) sobre a força de cisalhamento (kgf. cm-2) da carne de peito. Quanto à coloração, o aumento do período do jejum alimentar, tornou a carne de peito mais escura, porém não apresentou diferença significativa. Pelos dados da correlação dos atributos de qualidade, foi observada, para o valor de L*, uma relação negativa com o valor do pH da carne, pois, conforme aumentava o pH, o valor de L* diminuía. Observou-se, também, a correlação positiva entre o valor do pH e o CRA. Portanto, à medida que o pH da carne de peito aumentava, a CRA também incrementava. A correlação positiva encontrada entre a perda por cocção e a força de cisalhamento demonstrou que o aumento da perda de peso pela cocção influenciou negativamente a maciez da carne. De acordo com os resultados encontrados em relação ao rendimento de carcaças, o período entre 3 e 9h de jejum alimentar apresentou o melhor resultado. E quanto às qualidades físico-químicas da carne de peito de frango, não se encontrou diferença significativa entre os diferentes períodos de jejum. / The objective of this work was to evaluate the effect of different feed withdrawal periods (3, 6, 9, 12, 15 and 18 hours) on the weight loss of broilers raised in the conventional system and the yield of the hot and cold carcass (before and after cooling), as well as to evaluate the quality attributes of the broilers breast meat. In this experiment, 46-day-old Ross broilers were used. The results found in this study show that the prolonged feed withdrawal time had a significant effect (p&#8804;0,05) on the weight loss of the birds before slaughtering, with a 5% loss for a 12-hour feed withdrawal period. As the feed withdrawal periods increased, so did the amount of weight loss in the living carcass. The hot carcass yield was higher between 3 and 6 hours of feed withdrawal and reduced after 9 hours with a significant difference (p&#8804;0,05). As to the cold carcass yield, it decreased as the fasting time increased, with a significant difference (p&#8804;0,05) on the shear force (kgf. cm-2) of the breast meat. As to coloration, the increase in the feed withdrawal period made the meat darker, but no significant difference was found. According to the data from the quality attributes correlation, a negative correlation was observed between the L* value and the pH of the meat, for as the pH increased, the L* value decreased. A positive correlation was observed between the pH and the WHC, since, as the pH of the breast meat increased, so did the WHC. The positive correlation between the cooking loss and the shear force showed that the increase in the weight loss by the cooking influenced negatively the tenderness of the meat. According to the results found for the carcass yield, the best results were found for the fasting periods between 3 and 9 hours. As to the physical-chemical quality of the chicken breast meat, no significant difference was found among the different feed withdrawal periods.