Doctoral Degrees (Animal Sciences)

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Browsing Doctoral Degrees (Animal Sciences) by Subject "Animal nutrition -- Requirements"

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    Colouring the grey areas of insect mass-production to solidify their use as feed, food and biological control agents
    (Stellenbosch : Stellenbosch University, 2019-12) Woods, Michael Josias; Pieterse, Elsje; Hoffman, Louwrens Christiaan; Conlong, Desmond Edward; Goosen, Neil Jurgens; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Science.
    ENGLISH ABSTRACT: The mass-production of various insect species for biocontrol methods and as feed and food is becoming common practice and several different rearing facilities have been established across the world. Although insect mass-production facilities have been set in place, the mass- production of insects is still in an infantile stage and research is necessary to optimise these systems. As with conventional intensive livestock production the success of these systems, as well as the costs implicated, can largely be contributed to the nutrition of the animals. Trials were conducted to try and establish the nutrient requirements of selected insect species based on the body composition technique, a method commonly used for conventional livestock. Positive results were obtained for all involved insect species and led to an increase in production output, as well as to a decrease in the cost of production. For mass-produced insects to reach their full potential they need to be tailored for their end use. A study was conducted where larvae were reared on a substrate rich in polyunsaturated fatty acids in attempt to manipulate the fatty acids that they deposited into their biomass, and subsequently to evaluate the effect this had on the production and meat quality parameters of the animals the larvae had been fed to. Promising results were observed as an increase in the omega-3 fatty acids were observed in the larval biomass and the same occurred in the meat of the quails the enriched larvae were fed to. Although, the ratio of polyunsaturated- to saturated fatty acids could not be changed. Insect processing is another field that needs attention and the fractionation of insect biomass into protein, fat and chitin can result in significant increase in the margins made both environmentally and economically. An enzymatic fractionation method was developed that resulted in the isolation of protein, fat, and chitin and greater total recoveries were obtained compared to previous studies. The subsequent quantification of the chitin content of insects has also been a problem in the past and based on chitin isolation from crustaceans, a gravimetrical protocol was developed to address this issue. The resulting protocol led to the most repeatable and accurate estimation of the chitin content of insect larvae to date. Overall, the results obtained from the series of studies were a step in the right direction to solidify the mass-production of insects for biocontrol methods as well as for feed and food purposes.