Browsing by Author "Engelbrecht, J. A."
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- ItemEffects of varying sweet lupin dietary inclusion levels on feather classes, leather traits and meat composition of feedlot ostriches(South African Society for Animal Science, 2017-12-01) Brand, T. S.; Engelbrecht, J. A.; Van Der Merwe, J.; Hoffman, L. C.The main consumer products derived from ostriches are feathers, leather and meat. Despite progress in optimizing production practices, additional information is still necessary about the value of various raw materials as feed to ensure cost-efficient production. This study aimed to determine the effects of the gradual replacement of soybean oilcake meal with sweet lupin (Lupinus angustifolius) seed in the diet of feedlot ostriches on the feather, leather and meat production characteristics. The chicks received a standard commercial pre-starter ostrich diet, with the trial utilizing 141 ostrich chicks (± 10 chicks per group), beginning with the starter phase (83 days posthatching) and reared until 11 months of age. Five iso-nutritional diets were formulated for each feeding phase (starter, grower and finisher) according to specifications for each phase. In each phase, a control diet (Diet 1, 0% lupin diet (LD)) was formulated using soybean oilcake meal as the sole protein source and Diet 5 (100LD) was formulated to include the maximum amount of sweet lupin according to the specifications for the species and feeding phase. The maximum amount of sweet lupin included in 100LD therefore differs among the three feeding phases. The remaining three diets were formulated by gradually replacing soybean oilcake meal with lupins in the following increments: 100 : 0 (0LD); 75 : 25 (25LD); 50 : 50 (50LD); 25 : 75 (75LD), and 0 : 100 (100LD). There were three replications per treatment, resulting in 15 groups of birds. Feed and water were supplied ad libitum. No differences were found for moisture, crude protein and ash contents of the meat. However, the intra-muscular fat content was significantly influenced by the sweet lupin content of the diet. No differences were found for any of the feather classes that were measured. Regarding leather traits, the treatment diets had no effect on the crust sizes, leather grades, nodule diameters, and nodule densities. Differences were observed for leather thickness and pinhole number. It can be concluded that the sweet lupin inclusion levels evaluated in this study had little influence on leather traits, meat composition and feather classes.
- ItemEffects of varying sweet lupin dietary inclusion levels on feather classes, leather traits and meat composition of feedlot ostriches(South African Society for Animal Science, 2017-12-01) Brand, T. S.; Engelbrecht, J. A.; Van der Merwe, J.; Hoffman, L. C.The main consumer products derived from ostriches are feathers, leather and meat. Despite progress in optimizing production practices, additional information is still necessary about the value of various raw materials as feed to ensure cost-efficient production. This study aimed to determine the effects of the gradual replacement of soybean oilcake meal with sweet lupin (Lupinus angustifolius) seed in the diet of feedlot ostriches on the feather, leather and meat production characteristics. The chicks received a standard commercial pre-starter ostrich diet, with the trial utilizing 141 ostrich chicks (± 10 chicks per group), beginning with the starter phase (83 days posthatching) and reared until 11 months of age. Five iso-nutritional diets were formulated for each feeding phase (starter, grower and finisher) according to specifications for each phase. In each phase, a control diet (Diet 1, 0% lupin diet (LD)) was formulated using soybean oilcake meal as the sole protein source and Diet 5 (100LD) was formulated to include the maximum amount of sweet lupin according to the specifications for the species and feeding phase. The maximum amount of sweet lupin included in 100LD therefore differs among the three feeding phases. The remaining three diets were formulated by gradually replacing soybean oilcake meal with lupins in the following increments: 100 : 0 (0LD); 75 : 25 (25LD); 50 : 50 (50LD); 25 : 75 (75LD), and 0 : 100 (100LD). There were three replications per treatment, resulting in 15 groups of birds. Feed and water were supplied ad libitum. No differences were found for moisture, crude protein and ash contents of the meat. However, the intra-muscular fat content was significantly influenced by the sweet lupin content of the diet. No differences were found for any of the feather classes that were measured. Regarding leather traits, the treatment diets had no effect on the crust sizes, leather grades, nodule diameters, and nodule densities. Differences were observed for leather thickness and pinhole number. It can be concluded that the sweet lupin inclusion levels evaluated in this study had little influence on leather traits, meat composition and feather classes.
- ItemFeed preference of grower ostriches consuming diets differing in Lupinus angustifolius inclusion levels(South African Society for Animal Science, 2017-12-01) Brand, T. S.; Engelbrecht, J. A.; Van der Merwe, J.; Hoffman, L. C.Feed costs contribute the largest proportion of the input costs of slaughter birds in an intensive ostrich production unit. Alternative, cheaper feedstuffs, such as lupins (sweet and bitter cultivars), were therefore evaluated to determine the optimal lupin inclusion level in ostrich rations without affecting feed preference and intake. Sixty South African Black ostriches were randomly divided into ten paddocks of six birds per paddock. Three trials, with five different experimental diets, were conducted to investigate the diet preference of grower ostriches in a free-choice system. Feed and water were supplied ad libitum. The position of the diets in the successive paddocks was varied by rotating the five feed troughs in a clockwise direction, but within each paddock the position of each feeder and diet stayed the same throughout the three trials. In the first two trials, sweet (trial 1) or bitter (trial 2) lupins replaced soybean oilcake meal to have 0, 7.5, 15, 22.5, and 30% lupin inclusion levels in the diet. In trial 3 the soybean oilcake meal was replaced with either sweet or bitter lupins to have dietary inclusion levels as follows: 0% lupins, 15% sweet, 15% bitter, 30% sweet, or 30% bitter. The daily intake per group for each diet was monitored over a period of five days each. The average initial body weight of the birds was 73.6 ± 0.5 kg. No interaction was found between day and diet for the three trials and dry matter intake (DMI) did not differ between the five treatments for any of the three trials. In the second trial the birds tended to show a preference for the 7.5% bitter lupin inclusion level and discriminated against the 15% and 30% bitter lupin inclusion levels. Regression analysis of DMI on lupin inclusion rates revealed no significant trends. In conclusion, the study revealed that soybean oilcake meal can be replaced in the diets of grower ostriches by sweet lupin inclusion levels up to 30%, without any significant detrimental effect on diet preference and feed intake.
- ItemMachine learning for semantic segmentation of biomedical imaging data: ensemble 2D UNets for CT and PET images.(Stellenbosch : Stellenbosch University, 2021-12) Engelbrecht, J. A.; Nieuwoudt, M. J.; Malherbe, S. T.; Stellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.ENGLISH ABSTRACT: In Tuberculosis (TB) treatment response studies the manual delineation of the lung region in Computed Tomography (CT) scans is often required. This is a time consuming process. Manual delineations are required when abnormalities are present in the lung region, such as pronounced pathology caused by TB. Another problem requiring manual correction is misregistration. This is when composite Positron Emission Tomography (PET)/CT scans do not properly align based on anatomical features. Anatomical features in PET scans often extend into corresponding features of CT scans. This is undesirable. We propose a machine learning (ML) solution, based on the U-Net- and Tiramisu architectures for semantic segmentation, to delineate the lung region on CT scans, and correct misregistration on composite PET/CT scans. We create and train 2D implementations of these architectures. To compensate for the lack of spatial context of the 2D models, we combine multiple models trained on the three medical viewing angles to create a more robust ensemble solution, which reduces the amount of trivial false-positives. The CT based models were trained on 72 CT scans, with data augmentations applied. The PET based models were trained on 12 PET scans, also with data augmentation applied. For the CT based models, better results than previously reported were achieved. For the PET based models, improvements might be made with the addition of additional training data in the future. Finally, the CT based ensemble model is made accessible through a user friendly Jupyter notebook created with clinician use in mind.