RESUMO -Avaliou-se a digestibilidade aparente do milho, amido de milho, milho extrusado, germe de milho, sorgo, farelo de trigo, farelo de arroz, glúten 21, glúten 60, farelo de soja, farelo de canola, farelo de algodão, farinha de peixe, farinha de carne, farinha de vísceras de aves, farinha de sangue e farinha de penas. Confeccionaram-se 18 rações, marcadas com 0,10% de óxido de crômio III, uma delas, basal purificada, e as demais, contendo os ingredientes. Os peixes, 100 juvenis com 100±10 g, foram alojados em cinco tanques-rede para facilitar o manejo de alimentação e a coleta de fezes e permaneceram, durante o dia, em cinco aquários (250 L) de alimentação, recebendo refeições à vontade das 8 às 17h30. Após, foram transferidos para cinco aquários (300 L) de coleta de fezes, onde permaneceram até a manhã do dia subseqüente. O coeficiente de digestibilidade aparente dos ingredientes foi calculado com base no teor de óxido crômio da ração e das fezes. Com base nos resultados, concluiu-se que, entre os ingredientes energéticos, o milho apresentou o melhor coeficiente de digestibilidade aparente, seguindo-se o milho extrusado, o farelo de trigo e o farelo de arroz; dos ingredientes protéicos -vegetal, o glúten 60 e o glúten 21, seguidos do farelo de canola, apresentou os melhores coeficientes e dos protéicos -animal, destacou-se a farinha de vísceras de aves, seguida da farinha de peixes, enquanto os piores coeficientes foram proporcionados pela farinha de penas e farinha de sangue. Palavras-chave: digestibilidade, ingredientes, tilápia do Nilo, Oreochromis niloticus Apparent Digestibility of Feedstuffs by Nile Tilapia (Oreochromis niloticus)ABSTRACT -Apparent digestibility of corn, corn-starch, extruded corn, corn-germ, sorghum, wheat middlings, rice meal, corn gluten meal, gluten 60, soybean meal, canola meal, cottonseed meal, fish meal, meat and bone meal, poultry by-product meal, blood meal and poultry feathers hydrolyzed meal were determined for Nile tilapia juveniles (100±10 g) fed purified diet and 0.10% chromic oxide. Fish were maintained in 5 aquaria (250 L) at a density of 20 fish/aquarium for feeding, between 8a.m. and 5:30 p.m. After this period, they were transferred for aquaria (300 L) appropriate for fecal collection. The apparent digestibility of nutrient was determined by assessing the difference between the feed and fecal concentrations of the marker. Results of this study indicate that among energetic ingredients, corn, extruded corn, wheat middlings and rice meal had the highest apparent digestibility coefficient and gluten 60, corn gluten meal, canola meal for proteic ingredients. Among animal sources, poultry by-product and fish meal showed high apparent coefficients and, poultry feathers hydrolyzed and blood meal low apparent coefficients for Nile tilapia.

This study was undertaken in a closed system with Nile tilapia (Oreochromis niloticus) to examine the effects of total replacement of ¢sh meal (FM) by soybean meal. Nile tilapia ¢ngerlings with an average weight of 5.34 AE 0.08 g were hand-fed one of the ¢ve isoenergetic (% 13.5 MJ digestible energy kg À1 ) and isoproteic (% 31% of digestible protein) experimental diets to satiation, six times a day during 85 days in eight replicate ¢breglass tanks (six ¢sh per tank). The control diet containing FM was substituted by soybean meal, with and without essential amino acids (lysine, methionine and threonine) or dicalcium phosphate supplementation. The supplemental amino acids were added at levels to simulate the reference amino acid pro¢le of Nile tilapia carcass protein, based on the ideal protein concept. The results showed that soybean meal diet supplemented only with dicalcium phosphate was inferior to the control diet with FM and soybean meal diets supplemented with dicalcium phosphate and essential amino acids. Multiple essential amino acids and dicalcium phosphate incorporation in soybean meal diets was associated with performance, whole-body composition and carcass yield equal to that of the ¢sh fed with the control diet containing FM. These data suggest that a diet with all plant protein source, supplemented with essential amino acids, based on tissue amino acid pro¢le, can totally replace FM in a diet for Nile tilapia, without adverse e¡ects on the growth performance, carcass yield and composition.

RESUMO -O objetivo deste estudo foi determinar o coeficiente de digestibilidade aparente (CDA) dos aminoácidos do milho, farelo de trigo, farelo de soja e da farinha de peixe. Empregaram-se juvenis de tilápia do Nilo (Oreochromis niloticus) (25,24 ± 3,88 g) alimentados com ração referência peletizada contendo 0,10% de óxido de crômio (indicador) e 33,78% de proteína bruta. O CDA médio dos aminoácidos foi de: 88,31; 77,40; 91,78 Rev. bras. zootec., 30(4):1143-1149, 2001Introdução As rações comerciais para tilápias possuem de 25 a 40% de proteína bruta, o que implica em elevada participação de ingredientes protéicos, que correspondem a mais de 50% de seu custo. O aumento na produtividade requer a utilização de rações completas, pois o alimento natural não é capaz de atender as exigências dos peixes, principalmente quando criados em tanques-rede e "raceways", onde a elevada biomassa por área e as deficiências ou desbalanços de nutrientes podem acarretar perdas de produtividade e, conseqüentemente, menor retorno econômico.Uma ração formulada com base em proteína bruta ou aminoácidos totais pode não atender as necessidades nutricionais dos peixes. Deficiências ou excessos de aminoácidos interferem na utilização da fração nitrogenada, assim como na composição química e no rendimento de carcaça do peixe (WILSON et al., 1981). Dessa forma, uma ração completa, somente será obtida quando for conhecida a digestibilidade de todos os aminoácidos dos ingredientes que a compõe. Para tal, apresenta-se como fundamental a determinação da digestibilidade de aminoácidos dos principais ingredientes utilizados em sua confecção.O coeficiente de digestibilidade aparente (CDA) dos aminoácidos de fontes protéicas tem sido obtido principalmente para peixes carnívoros. Para essas espécies, a baixa eficiência de utilização dos aminoácidos do farelo de soja é associada ao elevado teor de carboidratos e inibidores de proteases (KROGDAHL et al., 1994), que são negativamente relacionados com o CDA (ARNESEN et al., 1989;

*Autor correspondente RESUMO: A diferença entre fontes alimentares da ordem de 14‰, originárias de plantas com ciclos fotossintéticos Carbono-3 (C3) e Carbono-4 (C4) e seus subprodutos, abre novas perspectivas para o estudo do metabolismo do carbono em aves e animais de pequeno porte. Os autores propõem um modelo teórico e experimental capaz de exprimir os resultados de enriquecimento relativo, delta per mil (δ‰) da razão 13 C/ 12 C versus tempo em diferentes tecidos. Utilizou-se a equação y(t) = (y0 -q/k) e -kt + q/k onde, y(t) é a concentração isotópica no tempo desejado, y0 a concentração isotópica inicial existente no tecido, k é uma constante de troca isotópica com unidade 1/tempo, t é unidade de tempo e q é a taxa de entrada de metabólitos que contém carbono, com valores de δ‰/tempo. Para fígado de galinhas que tiveram a ração de ciclo fotossintético C4 substituída por dieta C3 obteve-se a equação δ 13 C = -24,74‰ + 12,37‰ e -0.237(nT) , com meia-vida (T) de 2,9 dias. O patamar de equilíbrio de substituição do carbono foi alcançado em -24,48‰, de modo que praticamente 98,4% do conteúdo isotópico do C4 no fígado foi substituído por C3 após 5,6 meias-vidas. O modelo foi adequado para determinar o tempo de reciclagem total ou parcial da concentração de carbono nos tecidos em estudo. Palavras-chave: aves de postura, C3, metabolismo nutricional, δ 13 C, modelo teórico-experimental THEORICAL AND EXPERIMENTAL MODEL FOR CARBON-13 TURNOVER IN MAMMALIAN AND AVIAN TISSUESABSTRACT: Food source differences of about 14‰ from plants with carbon-3 (C3) and carbon-4 (C4) photosynthetic cycles and their derived products make carbon metabolism studies possible in birds and small mammals. The authors suggest a theorical and experimental model for determining the relative enrichment results, delta per thousand (δ‰) of the 13 C/ 12 C ratio as a function of time for different tissues. The following equation was used: y(t) = (y0 -q/k) e -kt + q/k where, y(t) is the isotopic concentration at time t, y0 is the initial isotopic concentration in the tissue, k is the turnover constant expressed in 1/time, and q is the input of metabolites which contain carbon expressed in δ‰/time. The equation below was obtained from the analysis of hen livers, the carbon-4 photosynthetic cycle ration of which was switched to a carbon-3 diet: δ 13 C = -24.74‰ + 12.37‰ e -0.237(nT) with 2.9 day half-life. The carbon switching steady-state was reached at -24.48‰ so that nearly 98.4% of the C4 isotopic content in the liver was replaced by C3 after 5.6 half-lives. The proposed model is suitable to determine the partial or entire turnover of carbon concentration in some selected tissues. Key words: hens, C3, nutritional metabolism, δ 13 C, theorical experimental modeling INTRODUÇÃOAs plantas dos ciclos fotossintéticos C3 e C4 e seus derivados, ou os seus subprodutos, apresentam valores isotópicos distintos. A diferença isotópica entre elas, da ordem de 14‰, permite realizar experimentos biológicos com alimentação utilizando-se a técn...

This present study aimed at evaluating the effect of the addition of an emulsifier to diets containing soybean oil, poultry fat or their blend, on the performance, carcass traits, serum lipid levels, pancreatic lipase concentration and nutrient digestibility of broilers. A randomized block design was applied using a 3 x 2 factorial arrangement, with three fat sources (soybean oil, poultry fat, and a blend of 50% soybean oil and 50% poultry fat) and the addition or not of an emulsifier. In experiment I, broiler performance, carcass traits, serum cholesterol, HDL, and triglyceride levels, and pancreatic lipase activity in 42-day-old broilers were evaluated. In experiment II, dry matter (DM), ether extract (EE), crude protein (CP) and crude fiber (CF) coefficients of digestibility were analyzed. Broilers fed the diet containing soybean oil and emulsifier presented higher body weight, weight gain and better feed conversion ratio. When birds were fed poultry fat and the fat blend (soybean oil and poultry fat) and the emulsifier was added to the diets, pancreatic lipase concentration increased. It was concluded that the use of soybean oil, poultry fat and their blend does no in the diet does not influence the performance, carcass traits, or serum cholesterol, HDL and triglyceride levels of 42-day-old broilers. The addition of emulsifiers to diets containing poultry fat improves ether extract digestibility and increases the production and secretion of pancreatic lipase

Bovine meat and bone meal (MBM) was widely used in animal diets until outbreaks of Bovine Spongiform Encefalopathy (BSE) occurred in some countries. It has not been confirmed yet whether or not BSE may be transmitted to man through chicken meat originated from poultry that had been fed diets containing MBM. Therefore, consumers nowadays express preference for meat originated from birds fed exclusively vegetable diets. This study analyzed samples of major breast muscle (Pectoralis major) using mass spectrometry of stable isotopes (carbon and nitrogen) as a means to assess the presence of MBM in broiler diets, a technique that might be used in the certification of poultry quality. A total of 150 day-old chicks were reared in five randomized treatments with increasing MBM dietary inclusion levels (0, 1, 2, 4 and 8%). On day 42, breast muscle samples were collected from three birds per treatment and used in the determination of

The present study was conducted to evaluate the effects of phytogenic additives (PA) and organic acids (OA), alone or in combination, on the performance, intestinal histomorphometry and lipid oxidation, and immune responses of broiler chickens. In this experiment, 820 one-day-old chicks were distributed according to a completely randomized design in a 2 × 2 + 1 factorial arrangement, with four replicates of 41 broilers each. The dietary treatments consisted of a control diet with no PA or OA (CD); CD with OA and no PA (CD+OA-PA); CD with PA and no OA (CD+PA-CD); CDwith both PA and OA (CD+PA+CD); and CD + avilamycin + monesin sodium. Broiler performance was not affected by the alternative feed additives, except from 1 to 21 days, when broilers fed the CD or CD+PA+OA diets showed higher body weight gain than those fed the CD with only OA. The broilers fed the diet containing avilamycin and monensin presented better performance. The supplementation of PA and OA increased bursalcortical area on21 and 42 days posthatch. On 21 days post-hatch, broilers fed the AGP diet presented higher ileal villus height than those fed the control diet. The pH values of the jejunum content were reduced on the OA-fed chickens. Higher villus height and crypt depth were found in the alternative additive-fed chickens on 7 days post-hatch. On 42 days post-hatch, the percentage of the bursal cortex increased in PA-fed broilers; however, there was no increase in antibody production. The PAfed chickens presented lower thiobarbituric acid reactive substances (TBARS) values in the small intestine. The dietary supplementation of phytogenic additives, individually or in combination associated with organic acids, does not affect broiler live performance or intestinal histomorphometry; however, it enhances immune responses and intestinal quality.

The contribution of growth and turnover to the muscle delta(13)C change process was investigated using mathematical models which associate delta(13)C change to time of intake of a new diet or increase in body mass. Two groups of Nile tilapia (Oreochromis niloticus) were fed on diets based on C3 (delta(13)C=-25.64+/-0.06 per thousand) or C4 (delta(13)C=-16.01+/-0.06 per thousand) photosynthetic cycle plants to standardize the muscle delta(13)C. After establishing the carbon isotopic equilibrium, fish (mean mass 24.12+/-6.79 g) then received the other treatment diet until a new carbon isotopic equilibrium could be established, characterizing T1 (C3-C4) and T2 (C4-C3) treatments. No significant differences were observed in fish productive performance. Good fits were obtained for the models that associated the delta(13)C change to time, resulting in carbon half-life values of 23.33 days for T1 and 25.96 days for T2. Based on values found for the muscle delta(13)C change rate from growth (0.0263 day(-1) and 0.0254 day(-1)) and turnover (0.0034 day(-1) and 0.0013 day(-1)), our results indicate that most of the delta(13)C change could be attributed to growth. The application of model that associated the delta(13)C change to body mass increase seems to produce results with no apparent biological explanation. The delta(13)C change rate could directly reflect the daily ration and growth rate, and consequently the isotopic change rates of carbon and other tissue elements can be properly used to assess different factors that may interfere in nutrient utilization and growth.