M C Soares

ISG | Business & Economics School, Lisboa, Lisbon, Portugal

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Publications (9)9.38 Total impact

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    ABSTRACT: 1. The supplementation of diets rich in soluble polysaccharides with microbial cellulases and hemicellulases decreases digesta viscosity and promotes broiler performance. 2. In contrast, recent experiments suggest that polysaccharidases are ineffective for improving the nutritive value of pasture biomass used by free-range broilers. However, the feasibility of using cellulases and hemicellulases to improve the utilisation of cereal-based feeds by pastured poultry remains to be established. 3. A study was undertaken to investigate the capacity of a recombinant cellulase from Clostridium thermocellum to improve the nutritive value of a barley-based feed for free-range pastured broilers of the RedBro Cou Nu x RedBro M genotype. 4. The results show that supplementation of a barley-based diet with a recombinant beta-glucanase had no effect on the performance of free-range broilers, foraging in legume-based diets from d 28 to 56. In addition, the results confirm that the lack of effect of the recombinant enzyme in improving the nutritive value of the barley-based feed does not result from enzyme proteolysis or inhibition in the gastrointestinal tract. 5. Significantly, beta-glucanase activity was identified in the crop of non-supplemented animals. The data suggest that endogenous cellulases originated both from the barley-based feed and from the crop microflora. 6. The results presented here suggest that in older birds of slow-growing genotypes associated with free-range production systems, previously unknown sources of beta-glucanases, such as the feed and microbial symbiotic microflora, can affect the effectiveness of exogenous enzymes added to the feed.
    British Poultry Science 06/2008; 49(3):347-59. · 1.15 Impact Factor
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    ABSTRACT: SUMMARY It is well established that the use of alfalfa in diets for monogastric animals is limited by its high fiber content. However, alfalfa is a natural source of xanthophylls and gives poultry products a desirably yellow color. In addition, alfalfa saponins may contribute to reduce the levels of cholesterol in the meat and egg yolk. We have investigated the potential utilization of β-glucanases and β-1,4-xylanases for enhancing the nutritive value of alfalfa for laying hens. An experiment was conducted with 864 ISA Brown layer hens from 40 to 52 wk of age and fed on diets containing rye (19.6%) or rye and alfalfa (15.1%). The results suggested that inclusion of alfalfa in the diets reduced body weights and total egg mass (P < 0.01). Dietary supplementation with polysaccharidases was unable to significantly improve the performance of laying hens. However, egg yolks from birds that consumed diets containing alfalfa were more deeply pigmented, presenting an increase in yellowness (b*). In contrast, at the percentage of incorporation tested, inclusion of alfalfa in the diets was unable to lower the levels of cholesterol content in the egg yolk. Taken together the results suggest that exogenous plant cell wall hydrolases are not effective for improving the nutritive value of alfalfa-containing diets for laying hens, although inclusion of small percentages of the dehydrated leguminous meal may directly affect the quality of the generated poultry products.
    The Journal of Applied Poultry Research 06/2006; 15(2). · 0.85 Impact Factor
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    ABSTRACT: Diets containing low-quality durum wheat (716 g/kg) for production of pasta were used to feed male broiler chicks. The efficacy of xylanase supplementation and the impact of xylanase inhibitors on losses in exogenous enzyme activity were analyzed. Birds fed on the basal diet, not supplemented with recombinant xylanases or Roxazyme G, reached a BW of 1,509 g with a feed conversion ratio of 1.77 at d 28. Growing performance was above that expected for the breed used, whereas feed conversion ratios were relatively higher. None of the 3 xylanase preparations under analysis affected growing performances and feed efficiency of broiler chicks. The activity of feed xylanases was considerably reduced in the presence of durum wheat extracts. The results suggest that reduction of exogenous enzyme activity was due to the action of durum wheat xylanase inhibitors and not to proteolysis.
    The Journal of Applied Poultry Research 12/2004; 13:660-666. · 0.85 Impact Factor
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    ABSTRACT: (1) Cellulases and xylanases display a modular architecture that comprises a catalytic module linked to one or more non-catalytic carbohydrate-binding modules (CBMs). On the basis of primary structure similarity, CBMs have been classified into more than 30 different families. These non-catalytic modules mediate a prolonged and intimate contact of the enzyme with the target substrate, eliciting efficient hydrolysis of the insoluble polysaccharides. (2) Xylanases are very effective in improving the nutritive value of wheat- or rye-based diets for broiler chicks although the role of non-catalytic CBMs in the function of exogenous modular xylanases in vivo remains to be determined. (3) A study was undertaken to investigate the importance of a family 6 CBM in the function of recombinant derivatives of xylanase 11A (Xyn11A) of Clostridium thermocellum used to supplement cereal-based diets for poultry. (4) The data show that birds fed on a wheat-based diet supplemented with the modular xylanase display an increased final body weight when compared with birds receiving Xyn11A catalytic module or birds receiving the enzyme mixture Roxazyme G. (5) Interestingly, the modular xylanase was truncated and transformed into its single domain counterpart on the duodenum of birds fed on the wheat-based diets, most possibly due to the action of pancreatic proteases. (6) Together the data point to the importance of CBMs in the function of feed xylanases and suggest, that in chicken fed on wheat-based diets, the main sites for exogenous enzymes action might be the gastrointestinal (GI) compartments preceding the duodenum, most probably the crop.
    British Poultry Science 11/2004; 45(5):648-56. · 1.15 Impact Factor
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    ABSTRACT: SUMMARY The use of alfalfa in diets for monogastric animals is limited by its high fiber content. However, it is well established that alfalfa is a natural source of xanthophylls, giving the poultry carcasses a desirable yellow color. We have investigated the potential use of cellulases and xylanases for enhancing the nutritive value of alfalfa for broiler chicks. In the first experiment, a commercial enzyme mixture and 2 recombinant cellulases and xylanases did not improve daily weight gains and feed efficiency of broilers between 35 and 56 d old, although animal performance was significantly depressed in animals supplemented with a recombinant xylanase. In a second experiment, alfalfa consumption was stimulated by restricting the consumption of the high energy feed to 50 and 75% from d 7 to 56. Alfalfa was offered separately and ad libitum and was supplemented or not with a commercial enzyme cocktail of polysaccharidases. While restriction of high energy feed had a drastic impact on the performance of broiler chicks, no improvements in weight gain and feed efficiency were observed due to enzyme supplementation. However, alfalfa consumption was lower in enzyme-supplemented animals, leading to smaller, but not significant, feed conversion ratios (FCR). Accumulated consumption of alfalfa meal ranged, in average, from 965 to 2,664 g/bird in experiments 1 and 2, respectively. The carcasses from birds with higher alfalfa intakes were more deeply pigmented with an increase in yellowness (b*) of the broiler skin.
    The Journal of Applied Poultry Research 09/2004; 13(3). · 0.85 Impact Factor
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    ABSTRACT: There is an urgent need in industrialized societies to develop novel products that can lower human dietary cholesterol intake. Dehydrated alfalfa is a good source of hypocholesterolemic compounds such as saponins. Whether consumption of alfalfa by chickens would decrease the cholesterol content of broiler meat remains, however, to be established. We determined meat quality characteristics, lipid and cholesterol contents, and consumer preference of broiler meat derived from production systems based on restricted feeding of a commercial diet combined with provision of free-choice dehydrated alfalfa. Results demonstrated that it was possible to produce chicken breast meat with reduced cholesterol content. In addition, total lipids in chicken meat were significantly decreased when a higher level of restriction was applied. Members of a 50-person consumer panel preferred meat from animals not consuming or consuming moderate levels of alfalfa. Those members that preferred meat from animals consuming the higher percentage of alfalfa identified taste as the primary attribute influencing that decision. Together the results suggest that it is possible to develop novel broiler production systems that will produce leaner meat that is acceptable to consumers and has a reduced cholesterol content.
    Poultry Science 06/2004; 83(5):810-4. · 1.52 Impact Factor
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    C Lapão, L T Gama, M C Soares
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    ABSTRACT: Two experiments were conducted with the purpose of determining the influence of broiler breeder age and storage time on egg albumen characteristics, embryonic mortality, and hatchability. Eggs from four commercial flocks of the same strain (Peterson x Minibro Shaver), under the same management and nutritional regimen, were incubated after storage at 16 C and 78% relative humidity, for periods of 0 (fresh), 1, 4, or 8 d. Albumen height and albumen pH were recorded immediately prior to each setting in Experiment 1 (eggs collected from 32- and 54-wk-old flocks) and at 0, 12, 24, 38, and 60 h of incubation in Experiment 2 (eggs from 42- and 59-wk-old flocks). Overall, albumen pH was 0.95 higher in eggs stored for 8 d than in fresh eggs, but most of this increase occurred during the first 4 d of storage. At 0 d of storage, pH increased (P < 0.05) with flock age, but age differences were negligible at 8 d of storage. Albumen height decreased with hen age and storage time (P < 0.05). Embryo viability was affected by the storage length by flock age interaction, such that longer periods of storage decreased viability in all flock ages. Decreased viability was pronounced in older flocks, with regression coefficients of viability on days of storage being -0.82 and -1.92% at 32 and 59 wk of age, respectively. The detrimental effects of storage time on viability in older flocks were mostly due to an increased incidence of culls and embryonic losses at all stages. Present results suggest that declines in hatchability with presetting storage start 1 d after lay, possibly due to deterioration in egg albumen quality.
    Poultry Science 05/1999; 78(5):640-5. · 1.52 Impact Factor
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    L H Reis, L T Gama, M C Soares
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    ABSTRACT: An experiment was conducted to assess how hatching performance is affected by breeder age and egg holding environment during short-term storage. Response variables analyzed were egg weight loss up to 18 d of incubation, viability (hatchability of fertile eggs), embryonic mortality, hatching time, and weight of male and female chicks, at hatching and at the end of incubation. The trials involved a total of 2,250 hatching eggs from each of two commercial broiler breeder flocks of the same strain (Avian) but of different ages (32 to 34 and 48 to 50 wk). Eggs were stored for 0, 1, or 2 d in the egg storage room or in the setter room. The hatching times of the chicks were recorded at 4-h intervals during the period from 478 to 494 h postincubation, and at 514 h, when incubation was terminated and all chicks were removed from the hatcher. In eggs from younger hens, viability was not influenced by preincubation storage; in older hens, viability of eggs not submitted to storage was higher (P < 0.05) by 3 to 6 percentage points than that of stored eggs. Hatching times were not affected by age of the hen, whereas male chicks tended to hatch, on average, about 3 h later than females. Chick weights at hatching and at removal from the hatcher were similar for both sexes, but females experienced a higher (P < 0.05) weight loss in that interval. Eggs incubated on the day of lay tended to hatch, on average, later than stored eggs (especially when compared to eggs submitted to 1 d storage), and produced heavier chicks.
    Poultry Science 11/1997; 76(11):1459-66. · 1.52 Impact Factor
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