Stability of native starch quality parameters, starch extraction, and root dry matter of cassava genotypes in different environments

Cassava is an important food and cash crop in Malawi. It is also becoming increasingly important for industrial use. The aim of this study was to investigate the native starch quality of different Malawi cassava genotypes. Trials were conducted at Chitedze and Makoka in Malawi in the 2000/01 season. Apart from root dry matter and starch extraction, starch quality parameters considered included protein, moisture and ash contents, pH and whiteness. Various stability measures were used to deal with the problem of genotype × environment interaction. The results showed that all the cassava genotypes produced starch with no protein and with colour as white as required by the industry. Moisture and ash contents and pH fell within the industry‐recommended ranges. This suggests that native cassava starch is suitable for use in various industries. Additive main effects and multiplicative interaction (AMMI) was strongly correlated with other measured stability parameters and is therefore recommended for stability analysis of starch quality parameters. Genotype had a larger influence than environment on root dry matter. This agrees with the hypothesis that one or a few major genes control root dry matter in cassava

The effect of genotype, location and season on cassava starch extraction

When cassava is harvested too early, it often leads to reduction in yield, while delayed harvest leads to development of woody and fibrous tuberous roots, and reduction in starch content. The optimum harvest time is not known. The objectives of this study were to determine the effect of genotype, location and season on starch extraction in order to find an optimum harvest regime for cassava, and to find the best parameter for monitoring starch levels in cassava tuberous roots. Results showed that genotypic effect was large for starch weight, starch extraction rate on fresh weight basis, and root dry matter content. This suggested that high starch weights could be realised by selection of suitable varieties for starch extraction. It was found that cassava harvesting and starch extractions should be done between October and November since the highest starch extraction rates were achieved during that period, and drying of the extracted starch using the open air method was fast and convenient. The results also suggested that starch levels can efficiently be monitored using starch extraction rate on fresh root weight basis. Starch content on fresh root basis and root dry matter content can also be used to determine the optimum time to harvest cassava for starch extraction but were inferior to starch extraction on fresh root weight basis

Effect of cassava leaf harvesting on root yield and quality

Cassava leaves are increasingly becoming an important source of nutrition for both human beings and livestock. A study was conducted at Chitedze Research Station, Malawi, to determine the effects of leaf harvesting on root yield and quality from 2003/04 to 2005/06 season. Two cassava varieties were used which included Mbundumali, a sweet variety with low potential for cyanogenic glucosides and widely grown by farmers; and Silira (TMS 60142B) an improved variety which is bitter, originated from IITA in tissue culture form and has high potential for cyanogenic glucosides. The experiment was laid out in a 2 x 3 x 2 factorial design in randomized complete block design replicated three times. Leaves were harvested using two methods of de-topping and ratooning while the leaves from the control were harvested at root harvest. Two fertilizer levels were used of which 92kg N per hectare were applied to some treatments and zero N to the others. Results indicated that leaf harvesting regardless of type of method used reduced cassava root yield, size, and dry matter content significantly (P<0.001). Ratooning method of cassava leaf harvesting produced the highest leaf biomass of about 25.0 tons fresh weight per hectare followed by de-topping (22 tons/ha) and control (9.0 ton/ha). An inverse relationship was observed whereby the more leaves were produced the less the root yield between. Mbundumali variety which has vigorous growth habits produced more leaf biomass and was least affected by leaf harvesting on root yield and dry matter content also

Característica leucocitária, relação albumina/globulina, proteína plasmática e fibrinogênio de bovinos da raça Nelore, confinados e terminados a pasto Leukocyte characteristic, albumin/globulin relation, plasmatic protein and fibrinogen of bovines of the Nelore race confined and grazing

Esse trabalho avaliou as mudanças na contagem de leucócitos e algumas proteínas séricas de bovinos confinados e terminados a pasto. De 120 amostras sangüíneas coletadas, 60 foram obtidas de bovinos Nelores machos confinados e 60 de animais com as mesmas características, porém manejados extensivamente. As amostras foram obtidas por ocasião do abate desses animais. Os parâmetros estudados foram contagem de leucócitos, razão albumina/globulina e concentração de fibrinogênio plasmático. Na análise dos dados empregou-se estatística descritiva, obtendo-se as médias, desvio padrão e coeficiente de variação para todos as variáveis avaliadas e posteriormente comparou-se as médias por meio de teste não-paramétrico. Os bovinos terminados a pasto apresentaram maior nível de globulina e fibrinogênio (P>0,05) quando comparados com os confinados (globulina: pastejo=3,29g dL-1 0,76; confinamento 2,99g dL-1&plusmn;0,60 e Fibrinogênio: pastejo=872mg dL-1&plusmn;610; confinamento=633mg dL-1&plusmn;319). O número de leucócitos total foi de 7,64&plusmn;2,15 em bovinos confinados e de 7,72&plusmn;1,84 nos terminados a pasto. Não houve diferença (P>0,05) entre essa variável e a contagem diferencial de leucócitos bem como na proteína sérica total (g dL-1) dos bovinos terminados a pasto (6,10&plusmn;0,53) e dos confinados (5,96&plusmn;0,49). O nível de albumina dos bovinos confinados (3,01g dL-1&plusmn;0,43) e a razão A/G (1,07&plusmn;8,91) foram maiores quando comparados com os bovinos terminados a pasto (2,82g dL-1&plusmn;0,45) e (0,95&plusmn;0,38) respectivamente. O nível mais elevado de albumina nos bovinos confinados sugere que eles foram submetidos a uma dieta nutricional mais adequada. O constante desafio imunológico sofrido pelos animais terminados a pasto pode ter sido responsável pelo elevado nível de globulina e fibrinogênio. Esses resultados indicaram que, apesar das adversidades que os bovinos confinados são submetidos, eles não apresentaram alterações correlacionadas com esse fato.<br>This research aimed to evaluate the changes in the white blood cell count and some serum proteins of confined cattle (CC) and grass cattle (GC). From the 120 blood samples collected, 60 were obtained from confined Nelore male bovines and 60 from animals with the same characteristics but managed extensively. Samples were obtained at the moment of slaughter. Parameters studied were the white blood cell count, serum albumin/globulin ratio and concentration of plasma fibrinogen. Descriptive statistics was used in the analysis of the data, and the averages, standard deviation and coefficient of variation calculated for all parameters evaluated. The comparisons between averages were made by non-parametric test. The grazing cattle showed higher levels of globulin and fibrinogen when compared to the confined ones (globulin: GC=3.29g dL-1&plusmn;0.76; CC=2.99g dL-1&plusmn;0.60 and Fibrinogen: GC=872mg dL-1&plusmn;610; CC=633mg dL-1&plusmn;319). The total number of white blood cells mL-1 was 7.64&plusmn;2.15 in confined cattle and 7.72&plusmn;1.84 in grazing cattle. There was no significant difference between this variable and differential white blood cell count as well as the total serum protein (g dL-1) from grazing cattle (6.10&plusmn;0.53) and confined cattle (5.96&plusmn;0.49). The level of albumin from confined cattle (3.01g dL-1&plusmn; 0.43) and the A/G ratio (1.07&plusmn;8.91) were greater when compared to the grazing bovines (2.82g dL-1&plusmn;0.45) and (0.95&plusmn;0.38) respectively. The higher serum levels of albumin found in confined herd suggest that they were subjected to a more adequate nutritional diet. The constant immunological challenge suffered by the GC could be responsible for the elevated serum levels of globulin and fibrinogen. These results showed that although feedlots present a stressful environment they did not show any blood alterations correlated to this fact