Effects of production systems and canola meal supplementation on carcass and meat quality characteristics of spent laying hens
- Authors: Semwogerere, Farouk
- Date: 2018
- Subjects: Broilers (Chickens) -- Feeding and feeds Chickens -- Feeding and feeds Chicken industry -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/9242 , vital:34309
- Description: This study evaluated the carcass and meat quality traits of spent laying hens as influenced by production systems (conventional cages and free range) and the inclusion/exclusion of canola meal in their diets. A total of 30 free range and 60 battery cage reared Lohmann Brown-Elite spent laying hens were obtained from a commercial egg producer. The 30 free range hens (53 weeks of age) and 30 of the caged hens (40 weeks of age) were fed a conventional diet, while the remaining 30 caged hens (48 weeks of age) were fed a diet supplemented with canola meal (20 percent). Carcass, portion and organ weights were determined. Physical attributes and proximate composition were analyzed for, with additional fatty acids and sensory profiles being determined for the effects of canola meal inclusion in the diet. Caged hens had heavier (P ≤ 0.05) warm and cold carcasses, thigh, wing and feet compared to free range hens. The percentages of the breast (26.1 ± 0.51 vs. 28.3 ± 0.28), drum, breast bones, breast thaw and cooking losses and thigh cooking loss were lower (P ≤ 0.05) for caged hens than for free range hens. Free range hens had heavier (P ≤ 0.05) gizzards (33.9 ± 1.04 vs. 30.5 ± 0.73) and bones and a lower (P ≤ 0.05) breast meat percentage (47.3 ± 0.94 vs. 51.7 ± 1.35). Meat redness (a*) (0.54 ± 0.222 vs. 1.40 ± 0.135) and hue angle value, skin redness (a*), breast and thigh, Warner-Bratzler shear force (WBSF) values (breast: 12.37 ± 0.411 vs. 17.10 ± 0.751, thigh: 29.68 ± 0.306 vs. 39.75 ± 0.826), breast moisture and thigh ash content were lower (P ≤ 0.05) for caged hens than free range hens. Caged hens had higher (P ≤ 0.05) thigh thaw loss and breast ash content than free range hens. Canola-fed hens had higher (P ≤ 0.05) drum percentages, breast bone weights and percentages, with lower (P ≤ 0.05) thigh and breast meat percentages. Canola-fed hens had lower (P ≤ 0.05) thaw losses, skin yellowness (b*) and Chroma values, breast fat content with higher cooking losses, skin redness (a*) and hue angle value, as well as breast WBSF (12.37 ± 0.411 vs. 15.43 ± 0.600). Palmitic acid, stearic acid, heneicosanoic acid acid, palmitoleic acid, saturated fatty acids (SFA) (34.0 ± 0.56 vs. 38.7 ± 0.71), n-6:n-3 polyunsaturated fatty acids (PUFA) ratio (5.5 ± 0.13 vs. 7.2 ± 0.28), atherogenic index (IA), thrombogenic index (IT), delta-5 desaturase (D5D, elongase index and thiosterase index were lower (P ≤ 0.05) for canola-fed hen breast meat. Breast meat from conventionally fed hens had lower (P ≤ 0.05) myristic acid, lignoceric acid, nervonic acid, alpha-linolenic acid (ALA), docosahexaenoic acid (DHA), PUFA:SFA ratio (0.7 ± 0.05 vs. 0.9 ± 0.02), n-3 PUFA (3.4 ± 0.31 vs. 5.1 ± 0.17), hypocholesterolemic:Hypercholesterolaemic (h/H), stearoyl-CoA desaturase 16 (SCD16) and stearoyl-CoA desaturase 18 (SCD18). The breast meat from conventionally fed hens had lower (P ≤ 0.05) metallic flavor than that from canola-fed hens. Strong positive correlations were observed for overall aroma with chicken (r = 0.965, P < 0.001) and brothy aroma (r = 0.827, P < 0.001); overall aroma with overall flavor (r = 0.680, P < 0.001), chicken flavor (r = 0.668, P < 0.001) and brothy flavor (r = 0.548, P = 0.006); initial juiciness with sustained juiciness (r = 0.771, P < 0.001) and tenderness (r = 0.537, P = 0.007); sustained juiciness with tenderness (r = 0.790, P < 0.001) and chewiness with residue (r = 0.783, P < 0.001). Whilst strong negative correlations were observed for: sustained juiciness with chewiness (r = -0.655, P = 0.001) and residue (r = 0.783, P < 0.001) and for tenderness with chewiness (r = 0.845, P < 0.001) and residue (r = -0.855, P < 0.001). Results of this study highlight that a free range production system when compared to a conventional cage system increased undesirable carcass and physical meat traits of spent laying hens. On the other hand, canola meal inclusion incorporates beneficial health aspects without affecting the sensory profile of meat derived from spent laying hens, both groups of hens being reared in battery cage system. Spent laying hen breasts can be consumed as a functional food (especially canolafed) since the fat content and composition was observed to be close to that which is recommended for a healthy diet.
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- Date Issued: 2018
Design, construction and performance evaluation of an agitated portable biogas digester under greenhouse-regulated temperature
- Authors: Mutungwazi Asheal
- Date: 2017
- Subjects: Sewage -- Purification -- Anaerobic treatment Green technology Renewable energy sources
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/9055 , vital:34222
- Description: Biogas yield in anaerobic digesters is negatively affected by low temperatures during cold seasons and nights, temperature fluctuations and inefficient agitation. Electrical heating and underground digester installations have been used to help minimise these effects but the high cost of electrical heating, infeasibility of underground installations in some terrains, inefficient agitation and difficult maintenance continue to be major set-backs to high biogas yields. In this study a 100 ℓ, agitated, portable carbon steel digester housed within a greenhouse, whose operation temperature is automatically maintained at an optimum of 35 ± 1 oC by means of an ON/OFF electronic circuit for ventilation control through a suitably sized window and insulation offered by an air film trapped in-between a double layer of polyethylene plastic covering of the greenhouse, was designed. Cow dung from a dairy farm at the University of Fort Hare with total solids (TS), volatile solids (VS), chemical oxygen demand (COD) and ammonia nitrogen content of 162348.67 mg/ℓ, 116543.98 mg/ℓ, 37 879 mg/ℓ and 128 - 235 mg/ℓ respectively was used for the performance evaluation of the digester. Analysis of the biogas produced starting from day 6 of the 31-day retention period showed a specific biogas yield of 0.036 m3/kgVSadded and a methane yield of 55percent. The optimum pH maintained was 7.2 and the COD reduction achieved during the digestion period was 61percent. This simple, easy to construct, inexpensive yet efficient design will lead to improved biogas yields and quality and faster dissemination of the biogas technology.
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- Date Issued: 2017
An assessment of participatory development and rural sustainable livelihoods in Zimbabwe : the case of Tsholotsho District
- Authors: Moyo, Walter Ntandoyenkosi
- Date: 2016
- Subjects: Community development -- Zimbabwe Rural development projects -- Zimbabwe
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/8419 , vital:32744
- Description: The central merits of this study and of the efforts invested throughout its development lie in its focus on participatory development and rural sustainable livelihoods. The main objective of the study was to assess the implementation of development projects in Tsholotsho district in Zimbabwe with regards to the issue of participation and its role to sustainable development. The study utilised the documentary research methodology which was used to gather data. The analysis of data was undertaken through the use of the participatory approach as the main theoretical framework. The study has shown that participatory development has been altered to take numerous and divergent forms that do not usher in the expected outcomes. Participatory development in Tsholotsho has thus taken a different stance since it has turned to be merely rhetoric and has suffered modifications and transformations to such an extent that power relations between and among development stakeholders subjugate the poor further leaving them without any voice. Community members are experiencing a ritual of empty processes that camouflage as participatory development making the people not to be centrally involved in bringing about rural sustainable development. One of the greatest challenges facing the rural development domain today is the search for alternative tools that seek to facilitate collective actions and solutions through the process of participation so that the poor get to be active not passive agents of development. This study is of the view that more research is needed to study the indigenous rural knowledge systems and their integration to modern knowledge systems; more so that is also a need to scrutinize the roles and responsibilities of NGOs interventions since they have made significant impacts in rural development. Finally, there is need to assess how policies affect development providers’ contributions in development processes.
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- Date Issued: 2016
The development and evaluation of a Nd:YAG laser incorporating an unstable resonator
- Authors: De Kock, Trevor Neil
- Date: 1986
- Subjects: Nd-YAG lasers , Lasers -- Resonators , Laser beams
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5512 , http://hdl.handle.net/10962/d1008566 , Nd-YAG lasers , Lasers -- Resonators , Laser beams
- Description: Introduction: For approximately the last eight years the Laser Section of the National Physical Research Laboratory (NPRL) has been interested in inter alia, pulsed solid-state lasers and in particular, Nd:YAG. Investigations of various resonator types were undertaken with a view to the improvement of the laser parameters such as output energy, pulse width, beam quality and sensitivity to mirror misalignment. In 1980 a Nd: YAG laser employing a rotating prism Q-switch was constructed (Preussler (1980)). It involves rotating one of the two cavity reflectors so that they are parallel for only a brief instant in time. Typically the prism must rotate at a speed of 20 000 r.p.m. to ensure a single pulse output. Such lasers suffer from the tendency to emit multiple pulses, they are very noisy and they require frequent maintenance because of the short lifetime of the bearings. A resonator employing conventional curved mirrors and an electro-optical Q-switch was constructed in 1980 (Robertson & Preussler (1982)). In 1981 an electro-optically Q-swi tched laser making use of a crossed Porro-prism resonator was investigated due to its relative insensitivity to misalignment of the reflectors compared with the conventional mirror resonator (Nortier (1981)). Improvements in terms of output power, beam divergence and beam quality can be achieved by making use of a so-called unstable resonator. Such a laser has been investigated and is reported on in this study. Chapter 2 provides some background into laser theory and operation while chapter 3 deals with the theory of the unstable resonator. Chapter 4 provides details of the experimental equipment and techniques used in the work and chapter 5 discusses the evaluation of the project and results obtained.
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- Date Issued: 1986
Adreno-active substances and the pineal gland
- Authors: Midlane, Graham Wallace
- Date: 1979
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3738 , http://hdl.handle.net/10962/d1001530
- Description: The pineal gland, a biochemically very active neuroendocrine transducer which is innervated by the sympathetic nervous system, was used in vivo to evaluate the effect of different þ-adrenoceptor agonists and antagonists on pineal enzyme levels. Hydroxyindole-O-methyltransferase (HIOMT), an enzyme with a circadian activity and unknown control was not significantly affected by these drugs. The activity of serotonin N-acetyltransferase, another pineal enzyme with a greater amplitude of circadian rhythmicity and which is under noradrenergic neural control, the degree of blockade depending on the selectivity and affinity of the agent used. An attempt was also made to alter the oestrous cycle of the rat by dosing with þ-active substances. Only propranolol had any effect on the oestrous cycle. It was not possible to establish an absolute link between the alteration in pineal enzyme activity and an influence on the oestrous cycle. It was concluded that the pineal enzyme studies are useful pharmacological means for evaluating þ-active substances
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- Date Issued: 1979