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Masters Degrees (Animal and Poultry Science)

Permanent URI for this collectionhttps://hdl.handle.net/10413/6571

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Browsing Masters Degrees (Animal and Poultry Science) by Subject "Animal nutrition."

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    Effect of roughage quality and period of meal termination on rumen fill.
    (2015) Adebayo, Rasheed Adekunle.; Verla, Nsahlai Ignatius.
    This study was conducted to test the hypotheses that (1) reticulo-rumen fill remains the same with changes in nutritional quality of roughages and (2) irrespective of when meal termination occurs, reticulo-rumen fill in morning, afternoon or evening would be equal. Based on these hypotheses, while it sought to develop a generic model for predicting the 'fill' of the reticulo-rumen of goats, it specifically determined (1) the reticulo-rumen fill and digesta loads in other compartments of the GIT of goats upon termination of meal in the morning, afternoon and evening (2) the effect of period of meal termination on the size of reticulo-rumen fill and other digesta loads (3) the effect of diet quality on feed intake, water intake, weight changes, digestibility and feeding behaviour of goats. Complementary to this, it lends a hand using artificial neural network (ANN) for prediction of reticulo-rumen fill. The study used 18 goats which were in groups of six assigned to three dietary treatments comprising urea-treated hay (UTH), urea-sprayed hay (USH) and non-treated hay (NTH). Reticulo-rumen fill decreased with increased quality of roughages while treatments also affected digesta load in other distal compartments of the digestive tract. Also, reticulo-rumen fill measured in the evening was larger than those of morning and afternoon. By implication, period of measurement also influenced the size of the fill. Besides, diet quality enhanced dry matter intake but its effect on water intake was not significant. Also, dietary treatments have great impact on dry matter degradation, digestibility of nutrients and the feeding behaviour of goats. ANN explained 37% and 22% of the variation between the observed and predicted reticulo-rumen fill of goats, in its training and validation model, respectively. In conclusion, ANN could be used for prediction of reticulo-rumen fill of goats.
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    Effects of diet quality and time lapse after meal termination on rumen load, rate of passage and feeding behaviour.
    (2016) Moyo, Mehluli.; Nsahlai, Ignatius Verla.
    Ruminant utilisation of poor quality feeds is governed by rates of degradation and passage through the rumen. Firstly, the passage rate of feed material determines the degree of bypass nutrients and the efficiency of synthesis of microbial protein in the rumen, making modelling of passage rate important. Secondly, diurnal feeding behaviours are not normally used in predicting feed intake although their influences are vital in understanding the dynamics of intake. Lastly, critical to rumen kinetics studies lies in understanding the dynamics of rumen fill levels post meal termination. The objectives of the study were to: (1) develop digesta passage rate prediction models for climatically, nutritionally and genetically diverse classes of ruminant herbivores; (2) ascertain the effects of diet quality on diurnal feeding behaviour in sheep and goats; and (3) determine the influence of diet quality on passage rates and, the extent and trend of solid digesta disappearance after meal termination. Artificial neural networks were used to develop prediction models for liquid and solid passage rates. Studies that reported fractional passage rates, class and body mass of ruminants were included in the dataset. Factors that affect rates of passage included animal and feed factors. The database was composed of observations of domestic and wild ruminants of variable body mass (1.5 to 1238 kg) from 74 studies and 17 ruminant species from different climatic regions. Observations were randomly divided into 2 data subsets: 75% for training and 25% for validation. Developed models accounted for 66 and 82% of the variation in prediction of passage rates for solid and liquid, respectively. On validation using an independent dataset, these models attained 42 and 64% of precision in predicting passage rates for solid and liquid, respectively. The effects of tropical roughage and diet quality on dry matter intake, duration and number of daytime and night time eating bouts, idling sessions and ruminating activities in small ruminants were investigated. Roughage quality was improved by urea treatment of veld hay, while diet quality was improved by supplementing with lucerne hay, sunflower meal, lespedeza, fish meal and sunflower meal. Day-time (0600-1800 h) and night time (1800-0600 h) feeding behaviour activities of sheep and goats were recorded. Generally, roughage and diet quality, and time of the day had significant effects on time spent ruminating and eating. Intake rates (g/bout and g/min) were not affected by diet and roughage qualities. Generally, goats and sheep fed on roughage alone ruminate at night and eat more during the day but those fed roughage and supplemented with lucerne hay spent more time ruminating than eating. Time spent eating and ruminating had positive correlations to feed intake. Intake rates (g/min and g/bout) had strong positive correlations to intake, which were significant. Improvement of roughage quality increased solid passage rate but did not affect liquid digesta passage rates from the rumen. Roughage quality had no effects on wet and dry digesta load in the foregut and hindgut compartments, except on abomasum dry matter load. Time lapse post feeding had no effects on rumen digesta load in the foregut and hindgut compartments, except on the dry and wet digesta load in the omasum. Proportions of digesta load in the rumen decreased linearly up to 24 h post feeding termination regardless of roughage quality. There is a possibility that this trend shapes into an exponential “decay” curve after 24 h post feeding termination. In conclusion, this study developed more précised prediction models for solid and liquid passage rates for ruminants fed on a variety of diets and/or feeds from different climatic regions. Roughage intake was limited as a result of increased rumination time of low quality roughages. There is a potential of using feeding behaviour to predict passage rates and predict intake. Digesta passage rate prediction models should include all animals, including those in a negative energy balance. The rate of clearance of digesta after meal termination was significantly greater for sheep fed on the improved roughage quality (IRQ) compared to the poor roughage quality (PRQ).