Browsing by Author "Hopley, Davina"

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    The evaluation of the potential of Tenebrio molitor, Zophobas morio, Naophoeta cinerea, Blaptica dubia, Gromphardhina portentosa, Periplaneta americana, Blatta lateralis, Oxyhalao duesta and Hermetia illucens for use in poultry feeds
    (Stellenbosch : Stellenbosch University, 2016-03) Hopley, Davina; Pieterse, Elsje; Stellenbosch University. Faculty of Agrisciences. Dept. of Animal Sciences.
    ENGLISH ABSTRACT: Insect protein as a source in poultry feed is slowly gaining popularity in terms of research. Therefore the purpose of this study was to look at unexplored aspects of insect protein, specifically its role in animal feeding. This involved investigating the chemical composition of selected insect species who have yet to gain popularity in this field, possible effects on gizzard erosion in broilers and total tract digestibilities, and also layer production and egg quality characteristics. In the first study, only eight of the potential nine insect species were selected for proximate analysis. The purpose of this study was to determine and evaluate the chemical composition of some insect species which have yet to be used in livestock feeds and which have the potential for mass rearing. On this basis, the following species were selected: Tenebrio molitor, Zophbas morio, Naophoeta cinerea, Blaptica dubia, Gromphardhina portentosa, Periplaneta americana, Oxyhaloa duesta and Blatta lateralis. These species were reared at the Department of Animal Sciences of Stellenbosch University. With 60.34%, N. cinerea yielded the highest CP value, which is comparable to that of fishmeal. The protein value for the other species were comparable to that of soya oilcake meal, with values ranging from 43.13% to 55.28%. The amino acid profiles for G. portentosa, P. americana and B. lateralis related best to the ideal amino acid profile for broilers. The purpose of the second study was to evaluate the possible effects of mealworms (the larvae of T. molitor) and the larvae- and pre-pupae of the black soldier fly (Hermetia illucens) on gizzard erosion in broilers. These two species were selected since they were easy to acquire in the required volumes. Also, the information available on H. illucens mainly regards animal broiler production parameters, but not this specific animal factor. Results of the study indicate the following: The mealworms caused significant (P < 0.05) gizzard erosion, whereas the others did not. The erosion may have been due to the high histidine content of the mealworms, which may have been transformed into histamine thereby causing erosion. Histidine may have also been transformed into gizzerosine, a potent inducer of gizzard erosion, during the drying process. The erosion observed may have also been due to the presence and form of chitin in the mealworms. Chitin is structurally similar to fibre, which was presented in a coarse form. Coarse fibres have been shown to increase the acidity of gizzard contents, which may lead to gizzard erosion. In the third study the total tract digestibility for mealworms was evaluated and compared to values from studies on other species as well as that of soya oilcake meal and fishmeal. It was found that the dry matter (DM) digestibility for mealworm meal is similar to that of housefly larvae meal and housefly pupae meal, but lower than that of black soldier fly meal. The CP digestibility was similar to that of black soldier fly meal and soya oilcake meal, but higher than that of housefly larvae meal and housefly pupae meal. The coefficient of total tract digestibility (CTTD) values for methionine and threonine are similar to that of soya oilcake meal and fishmeal. The CTTD value for lysine, however, was lower than all other protein sources presented. The low digestibility value may be attributed to specific processing conditions, especially overheating. The effects of the inclusion of mealworm meal and black soldier fly larvae- and pre-pupae meal on layer production performance and egg quality characteristics were evaluated by comparing to a balanced control diet. There were no significant (P > 0.05) differences in average daily gain (ADG) between treatments. The feed conversion ratio (FCR) for the black soldier fly pre-pupae meal was significantly (P < 0.05) lower than the other treatments. The egg weights for the control diet was significantly (P < 0.05) less than the treatment diets. There were however no significant differences between the other treatments. The yolk weights did not differ significantly between the treatments and control. The shell weight for the mealworm diet was significantly higher than that of the control and the black soldier fly larvae- and pre-pupae diets. The albumin weight and albumin height for the mealworm diet differed significantly from the control, although it did not differ significantly (P < 0.05) from the rest. General results are in support of the use of these insects as protein in poultry feeds.