The impacts of Hg 2+ , Cd 2+ and Zn 2+ on the activities of periplasmic nitrate reductase (NAP) and dehydrogenase (DHA) enzymes of three organisms isolated from soil and sediment-water interface were analysed in liquid culture studies. NAP and DHA activities were estimated from nitrite and triphenyl formazan produced respectively after 4h incubation at 28 ± 2 o C. Hg 2+ completely inhibited NAP activity in Escherichia and Pseudomonas spp. at all the concentrations (0.2 -1mM) while progressive inhibitions of NAP activity were observed in Escherichia and Pseudomonas spp. with increasing concentrations of Zn 2+ and Cd 2+ . Both metals were stimulatory to NAP of Acinetobacter sp. at 0.2 -1mM. Apart from stimulation of DHA activity by Zn 2+ (0.2 -1mM) in Escherichia sp., Cd 2+ (0.4 -1.0mM) in Acinetobacter sp. and (1.0mM) in Pseudomonas sp., all the metals progressively inhibited DHA activities in the three organisms. In Escherichia sp., the activities of the two enzymes were negatively correlated on exposure to Zn 2+ (r = -0.91) and positively correlated (r = >0.90) on exposure to Cd 2+ and Hg 2+ . Based on IC 50 values of the metals for the DHA and NAP enzymes, the most resistant of the three organisms were Escherichia sp. and Acinetobacter sp. respectively. Quantitatively, NAP with its lower IC 50 values than DHA was a more sensitive toxicity measure for Hg 2+ in all the organisms. The sensitivity of microbial metabolic enzymes to the toxic effects of metals varies with the type of enzyme, metal and the microorganism involved. Keywords: Periplasmic nitrate reductase; Dehydrogenase; Escherichia sp.; Pseudomonas sp.; Acinetobacter sp.; IC 50 ; Hg 2+ ; Cd 2+ and Zn 2+ . Palavras-chave: Reductase do nitrato periplásmico; dehidrogenase; Escherichia sp; Pseudomonas sp; de Acinetobactéria sp; IC 50 ; Hg 2+ ; Cd 2 + e Zn 2+ .
Studies were conducted to determine the relative effects of fermented and unfermented sun-dried cassava tuber meals as source of energy in broiler diets. A batch of fresh bitter cassava tubers (TMS 30572 variety) was cut into pieces, dried in the sun and milled (UFC). Another batch was cut into pieces, fermented in water for 4 days, dried in the sun and milled (FC). Both fresh cassava tubers and processed meals were analyzed for proximate composition and cyanide contents. In the first experiment, the meals were used to make 7 iso-nitrogenous broiler starter diets such that diet I (the control) contained maize as source of energy while in diets 2, 3 and 4, 50%, 75% and 100% of the maize in the control diet was replaced with UFC and in diets 5, 6 and 7, the maize was similarly replaced with FC. Each diet was fed to a group of 24 broiler chicks replicated into 2 from / week old to 5 weeks old. In the second experiment, the meals were used to make 7 iso-nitrogenous broiler finisher diets, using replacement levels as in the starter trial, and each diet fed to a group of 22 broiler chicks replicated into 2 from 5 weeks old to 9 weeks old. Fresh cassava tuber contained 0.44mg HCN/gm while unfermented and fermented meals contained 0.15mg HCN/gm and 0.08mg HCN gm, respectively. There were no significant differences (P>0.05) in proximate composition of the three samples. In the starter trial, the group that received the diet in which 50% of maize was replaced with UFC or FC compared favourably with the control in performance (P>0.05). Although at 100% replacement level, both UFC and FC significantly depressed performance of the chicks, UFC resulted in severe stunted growth and ruffled feathers of the chicks. In the broiler finisher trial, replacement of maize up to 75% with FC produced no adverse effect (P>0.05) whereas at that level, UFC significantly depressed performance (P>0.05).
Considering the inherent attributes of cocoyam (Xanthosoma sagittifolium), its appropriate utilization for chicken diets may enhance performance of starter broilers. The study was therefore, carried out to determine the growth performance of starter broilers fed processed cocoyam tuber meal as energy source in place of maize. Xanthosoma cocoyam corms were harvested, cleaned of soil and chopped into bits of about 0.2 cm. The chopped tannia was soaked in water in a large vat for 24 hours to reduce the ant nutrients and later on separated from the water and dried with microwave oven. The dried cocoyam was milled and then used. The proximate chemical composition showed that soaked cocoyam tuber meal contained 8.05% moisture, 91.95% dry matter, 10.08% ash, 2.01% crude protein, 1.60% ether extract, 3.80% crude fibre, 74.46% NFE and 3158.92Kcal/kg DM metabolizable energy. In the starter broiler experiment, five experimental diets were formulated such that, diet 1 (control) contained yellow maize as the main energy source, while soaked CTM was used to replace maize at levels of 15%, 20%, 25% and 30% respectively in the control diet. Each starter diet was fed to a group of 30 broiler chicks for 4 weeks using completely randomized design. Each treatment was further grouped into 3 replicates of 10 birds each. The broiler chicks were kept in deep litter and given feed and water ad libitum. Parameters measured included initial body weight, final body weight, feed intake, feed conversion ratio and cost of production. In the starter feeding trial, the group on 30% soaked CTM (30% SCYM) compared favorably with the control group (P<0.05) and recorded the highest body weight gain. It appeared that, the starter broilers could tolerate high levels of soaked CTM in their diets. Cost of production (cost of feed x feed conversion ratio) was lowest for diet 5 (30% SCYM) N248.15 as against N281.86 for control diet in the starter feeding trial. CTM meal can be used to replace maize at 30% in the diets of starter broilers without affecting weight gain, feed intake and feed conversion ratio as indicated in the study.
Considering the inherent attributes of cocoyam tuber meal (Xanthosoma Sagitifolium), its appropriate utilization for chicken diets may enhance performance of broiler chicken. This studywas therefore carried out to determine the nutritional evaluation of fermented cocoyam tuber meal as energy source in the diets of starter broilers production. The fermented cocoyam was used to replace maize at various levels to determine the best replacement would give optimal performance in starter broilers diets. One hundred and fifty 150 day old Agrited starter broilers were used for this experiment,. The proximate composition of fermented cocoyam tuber meal (FCYM) showed that it contained 19.5% moisture, 1.30% ash, 3.56% Crude protein, 5.30% crude fibre, 1.9% ether extract and 25.48% NFE. In the starter feeding trial, the fermented cocoyam was used to replace maize at levels of 25%, 50%, 75% and 100% respectively in the control diet. Each starter diet was fed to a group of 30 broilers chicks for four weeks using completely randomized design. Each treatment was divided into three replicates of 10 broiler chicks each. Parameters measured include initial body weight, final body weight, body weight gain, feed intake, feed conversion ratio and cost of production. In the starter feeding trial, the starter broilers on 25% FCYM compared favorably with those on the control diet (P>0.05) in terms of feed intake, feed conversion ratio and body weight gain and hence recorded the higher body weight gain. The cost per kg feed produced was N182.50 for the control diet and the lowest was diet 5 (100% FCYM) which was N82.74. The cost of production (cost/kg feed x feed conversion ratio) of starter broilers per kg body weight gain was lowest for diet 5 (100% FCYM) (N158.86), while the costliest was those on the control diet (N383.25). The results of the trial have shown that fermentation of cocoyam tuber meal for 4 days for formulating starter broiler diets was quite an effective method of processing because fermentation reduced the anti-nutrients content. It was concluded that fermented cocoyam tuber meal could be used in the diets of starter broilers up to 25% without affecting body weight gain, feed intake and feed conversion ratio as indicated in this study.
Energy feed source like maize is expensive contributing about 50-55% of the cost of poultry and pig diets. Thus, the study was carried out to determine the dietary substitution of maize with soaked cocoyam Xanthosoma sagittifolum as energy source for finisher broiler production. The soaked cocoyam tuber meal was used to replace yellow maize in the diets of finisher broilers. Xanthosoma cocoyam corms were harvested, cleaned of soil and chopped into bits of about 0.2 cm. The chopped tannia was soaked in water in a large vat for 24 hours to reduce the ant nutrients and later on separated from the water and dried with microwave oven. The dried cocoyam was milled and then used. The proximate chemical composition showed that soaked cocoyam tuber meal contained 8.05% moisture, 91.95% dry matter, 10.08% ash, 2.01% crude protein, 1.60% ether extract, 3.80% crude fibre, 74.46% NFE and 3158.92Kcal/kg DM metabolizable energy. In the finisher broiler trial, the control diet contained maize as the main energy source while diets 2, 3, 4 and 5 contained 15%, 20%, 25%, and 30% soaked cocoyam tuber meal finisher diet was fed to a group of 30 broiler chicks for 4 weeks using completely randomized design. Each treatment was further grouped into 3 replicated of 10 birds each. The broilers were kept in deep litter and given feed and water ad libitum. Parameters measured included: initial body weight, find body weight, body weight gain, feed intake, feed conversion ratio, cost of production and carcass characteristic. In the finisher feeding trial, the finisher broilers on the control diet, diet 5 (30% SCYM), and diet 3 (20% SCYM) recorded similar feed intake which were significantly different (P<0.05) from those on the other diets. In terms of body weight gain, the finisher broilers on 20% soaked cocoyam tuber meal diet recorded significantly (P<0.05) high body weight than those on other diets while the finisher broilers on 25% soaked cocoyam tuber meal recorded the poorest body weight gain. It appeared that, the finisher broilers could not tolerate high levels of soaked cocoyam tuber meal in their diets. Cost of production (cost of feed x feed conversion ratio) was lowest for diet 5 (30% SCYM) N375 versus N422.99 for control diet in the finisher trial. The internal organs expressed as percent of the live weight were not affected by the treatments. The finisher broilers on diet 3 recorded the highest dressing out percentage of 73.90.There were no significant difference (p<0.05) on percentage wings and back cut of the finisher broiler group in all the diets. The finisher broilers on diet 4 (25% SCYM) yielded the highest percent breast muscle of 32.4% followed by those on 15% SCYM (diet 2) and 20 SCYM (diet 3). The finisher broilers on the control diet yielded the highest percent thigh of 18.3% and the poorest were those on diet 2(15% SCYM). The results of the trial have shown that soaked cocoyam tuber meal can be used to substitute maize at 20% in the diets of finisher broilers without affecting the weight gain, feed intake and feed conversion ratios as indicated in this study.
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