Food restriction reduces neurogenesis in the avian hippocampal formation

The mammalian hippocampus is particularly vulnerable to chronic stress. Adult neurogenesis in the dentate gyrus is suppressed by chronic stress and by administration of glucocorticoid hormones. Post-natal and adult neurogenesis are present in the avian hippocampal formation as well, but much less is known about its sensitivity to chronic stressors. In this study, we investigate this question in a commercial bird model: the broiler breeder chicken. Commercial broiler breeders are food restricted during development to manipulate their growth curve and to avoid negative health outcomes, including obesity and poor reproductive performance. Beyond knowing that these chickens are healthier than fully-fed birds and that they have a high motivation to eat, little is known about how food restriction impacts the animals' physiology. Chickens were kept on a commercial food-restricted diet during the first 12 weeks of life, or released from this restriction by feeding them ad libitum from weeks 7-12 of life. To test the hypothesis that chronic food restriction decreases the production of new neurons (neurogenesis) in the hippocampal formation, the cell proliferation marker bromodeoxyuridine was injected one week prior to tissue collection. Corticosterone levels in blood plasma were elevated during food restriction, even though molecular markers of hypothalamic-pituitary-adrenal axis activation did not differ between the treatments. The density of new hippocampal neurons was significantly reduced in the food-restricted condition, as compared to chickens fed ad libitum, similar to findings in rats at a similar developmental stage. Food restriction did not affect hippocampal volume or the total number of neurons. These findings indicate that in birds, like in mammals, reduction in hippocampal neurogenesis is associated with chronically elevated corticosterone levels, and therefore potentially with chronic stress in general. This finding is consistent with the hypothesis that the response to stressors in the avian hippocampal formation is homologous to that of the mammalian hippocampus

Brain and hepatic Hsp70 protein levels in heat-acclimated broiler chickens during heat stress

In the present study we have investigated the effects of heat acclimation on brain and hepatic Hsp70 protein levels and body temperature of broiler chickens in response to gradual heat stress. Two groups of broilers were raised up to 47 days of age under distinct temperature conditions: thermoneutral (TN, according to bird age) or hot environmental (HS, 31-33°C). At 46 days of age, the birds reared at high ambient temperature were transferred to thermoneutrality conditions. After 18 h, these birds and the birds reared at thermoneutral temperature were submitted to gradual heat stress in a climatic chamber so that environment temperature was increased from 28 to 40ºC at a rate of 2ºC/h. Colonic temperature was measured using a thermometer sensor probe at each two hours, and hepatic and brain tissues were collected immediately after slaughter in order to assess Hsp70 protein level by Western blotting analysis. The colonic temperatures of birds reared at high temperature increased steeply during the first 2 h of heat stress (1.06ºC/h) and more slowly thereafter (0.59ºC/h). Broilers reared at thermoneutral temperature showed a small increase in the first 4 h of heat stress (0.18ºC/h) and then colonic temperature increased sharply (0.72ºC/h). Nevertheless, both groups presented similar final colonic temperature by the end of the stress period. Hsp70 levels (ng Hsp70 µg total protein-1) did not change in the liver or brain of the birds reared at high temperature. on the other hand, both liver and brain Hsp70 levels increased significantly during heat stress in the animals reared at thermoneutrality, with a higher expression of this peptide in brain tissue

Resultados de Pesquisa em Nutrição de Aves no Brasil: Resumo dos Ultimos 5 anos Results of Poultry Nutrition Research in Brazil: A Summary of the Last 5 years

Foi realizada uma revisão bibliográfica sobre as pesquisas brasileiras na área de nutrição avícola, entre 1994 a l999. Nesse período, foi publicado um total de 496 trabalhos, com uma média de 82,7 trabalhos/ ano. Os trabalhos na área de nutrição revelaram que 64,52% foram realizados com frangos de corte; 24,19%, com poedoiras e aves de reposição; 3,93%, com matrizes pesadas; e 7,66%, com outras aves. Com relação às publicações em forma de resumos expandidos, foram publicados 226 e 163 resumos, nos Anais das Reuniões Anuais da Fundação APINCO de Ciência e Tecnologia Avícolas e da Sociedade Brasileira de Zootecnia, respectivamente. Na Revista da Sociedade Brasileira de Zootecnia e no Arquivo Brasileiro de Medicina Veterinária e Zootecnia foram publicados, respectivamente, 65 e 34 trabalhos completos. Os pesquisadores das instituições UFV, UNESP-Jaboticabal e UFRGS publicaram no total 104, 92 e 46 trabalhos. As pesquisas concentraram-se principalmente nas áreas de proteína/aminoácidos (21,77%), avaliação de alimentos (21,77%), minerais (19,15%) e aditivos (16,33%).<br>A literature review of the papers published in the area of poultry nutrition was done considering Brazilian publications from the period of 1994 to 1999. During this period a total of 496 papers were published, with an average of 82. 7 papers/year. The publications in nutrition revealed that 64. 52% were made with broiler chickens, 24. 19% with laying hens and replacement birds, 3.93% with broiler breeders and 7.66% with other type of birds. Considering the publications in the form of summary, 226 and 163, were published in the Proceedings of Fundação APINCO de Ciência e Tecnologia Avícola and Sociedade Brasileira de Zootecnia, respectively. In the Revista da Sociedade Brasileira de Zootecnia and Arquivo Brasileiro de Medicina Veterinária e Zootecnia were published, 65 and 34 papers, respectively. Researches in the Universities UFV, UNESP-Jaboticabal and UFRGS, accounted for a total 104, 92 and 46 papers, respectively. The papers in poultry nutrition concentrated mainly in the area of protein/amino acid (21.77%), feedstuffs evaluation (21.77%), minerals (19.15%) and additives (16.33%)