Haematological studies on frizzled and naked neck genotypes of Nigerian native chickens

Variation in haematological parameters of Nigerian native chickens was studied using 60 clinically normal frizzle-feathered, naked-neck, and normal-feathered native chickens. These included red blood cell count, haemoglobin, packed cell volume, white blood cell count, mean corpuscular volume, mean corpuscular haemoglobin concentration, serum glucose, urea, cholesterol, albumin, globulin and creatinine. Normal-feathered birds had higher (p < 0.05) mean values compared to frizzled and native neck genotypes except for albumin, red blood and white blood cells, and mean cell haemoglobin concentration. Males generally had higher mean values than their female counterparts across all genotypes. Correlation coefficients among the parameters were significant (p < 0.001) with r values ranging from 0.26 between red blood cell and mean corpuscular haemoglobin to 0.92 between red blood cell and cholesterol. Sufficient genetic variation therefore exists for haematological parameters among Nigerian native chickens that may represent indicator traits for further study. However, the application of molecular tools will provide better understanding and application of these differences.     

Application of principal component and discriminant analyses to morpho-structural indices of indigenous and exotic chickens raised under intensive management system

The objectives of this study were to investigate the relationships between body weight and morpho-structural indices to predict body weight from their orthogonal body shape characters using principal component analysis and to morphologically classify the chicken genotypes using multivariate discriminant analysis. Data used were from 273 randomly selected 12-weeks-old indigenous chickens of normal-feathered (NF), frizzle-feathered (FF), naked-neck (NN) and Anak Titan (AT) genotypes. Phenotypic correlation among body weight and most biometric traits ranged from 0.227-0.876, -0.7-0.901, 0.034-0.968 and -0.207-0.849 for NF, NN and AT chickens, respectively. Factor analysis with varimax rotation of interrelated traits revealed three principal components which accounted for 83.1%, 74.4%, 78.8% and 76.5% of the total variance in NF, FF, NN and AT chickens in the order listed. Breast girth, keel length, thigh length, shank length and wing length were found to be the most discriminating variables to separate the chicken genotypes. The longest distance (72.54) occurred between AT and NF genotypes while the shortest distance (4.27) was recorded for FF and NN genotypes. Classification results showed that 85.2% of AT genotype was correctly classified into their source population. However, 22.7% of NF was misclassified as NN, while 33.3% of NN was misclassified as NF chickens. These results suggest that there is high rate of gene flow between these two indigenous chicken genotypes. Information obtained from this study may be considered useful in breed improvement programmes for selection, characterization, conservation and better management of Nigerian indigenous chickens.     

Optimal control of foliar disease dynamics for multiple maize varieties

Maize is a very important food crop world-wide and is vulnerable to diseases. Maize varieties that have high disease resistance are highly recommended for economic and health reasons. We consider a maize field with multiply varieties and develop a mathematical model to investigate the impact of foliar disease on the population dynamics. The possible benefit of considering control measures in reducing the spread of foliar diseases are evaluated. Results show that farmers must be aware of the disease dynamics of each variety as the dynamics vary. Also, in controlling diseases some methods are more effective than others. For the example given here controlling susceptibility of seeds to disease was the most effective method. As controlling diseases can be costly, optimal methods are important. Our results show that the most effective controls are those introduced at the outset of an outbreak and this can reduce the spread of diseases with the least cost.     

Prediction of body weight from body measurements in grass cutters

In order to predict the body weight of grass cutters from linear body measurements, the weights and measurements of 50 intensively managed female grass cutters aged 5 months were fitted into linear, quadratic and cubic regression models. Highly significant (p?<?0.01) R ² values ranging from 74 to 98 % were obtained indicating that all body measurements were good predictors of body weight. Although quadratic and cubic models gave slightly higher R ² values than linear models, it is recommended that farmers should use a simple linear equation based on tail length or heart girth to predict the body weight of their grass cutters. The recommended equations are (weight in kg)?=?0.47?+?0.08 (tail length in cm) and (weight in kg)?=?0.32?+?0.07 (heart girth in cm).     

Optimal control of maize foliar diseases using the plants population dynamics

Pathogens and insects can have important negative effects on yields of crops cultivated by humans. These effects can be important for the food security or financial well-being of individuals. In particular, maize is a very important staple crop worldwide and is vulnerable to diseases. We formulate here a mathematical model to evaluate the impacts of foliar diseases on the population dynamics of maize plants. Qualitative analyses of the important mathematical features of the model are carried out. We show how this methodology can be extended to reducing the spread of foliar diseases through effective control measures with minimum costs.