- Title
- Effects of production systems and canola meal supplementation on carcass and meat quality characteristics of spent laying hens
- Creator
- Semwogerere, Farouk
- Subject
- Broilers (Chickens) -- Feeding and feeds Chickens -- Feeding and feeds Chicken industry -- South Africa
- Date Issued
- 2018
- Date
- 2018
- Type
- Thesis
- Type
- Masters
- Type
- MSc
- Identifier
- http://hdl.handle.net/10353/9242
- Identifier
- 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.
- Format
- 138 leaves
- Format
- Publisher
- University of Fort Hare
- Publisher
- Faculty of Science and Agriculture
- Language
- English
- Rights
- University of Fort Hare
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UFH Department of Livestock & Pasture Science
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