Beef quality, oxidative stability and fatty acid composition of Nguni heifers fed diets with incremental levels of Opuntia ficus-indica (cactus) cladodes
- Authors: Mkhosi, Silungile
- Date: 2020
- Subjects: Meat -- Quality
- Language: English
- Type: Thesis , Masters , MSc (Animal Science )
- Identifier: http://hdl.handle.net/10353/18732 , vital:42728
- Description: The objective of the study was to determine meat quality, fatty acid (FA) composition and shelf-life stability of longissimus muscle of Nguni heifers fed incremental levels of Opuntia ficus-indica (cactus) cladodes. A total of 32 heifers aged 36 months were allocated randomly to four dietary treatments: 10% cactus, 20% cactus, commercial and control diets for 90 days. The longissimus thoracis et lumborum (LTL) samples were taken from each carcass for the determination of meat quality, retail shelf-life stability and FA composition. Diet had no effect (P > 0.05) on pH and drip display, however, there was an increase in drip display with ageing time (P ≤ 0.05). Meat colour attributes (L* a* b* and C*) were influenced by diet, with 20% cactus diet having lower L* values compared to other diets (P ≤ 0.05). During a 14-day retail display, a diet day interaction was observed for hue angle with the cactus diets having the lowest values at day 14 of display compared to the other diets (P ≤ 0.05). Differences in meat from heifers fed different diets were observed with 20% cactus accounting for significantly (P ≤ 0.05) higher levels of deoxymyoglobin and the lowest levels of oxymyoglobin. Thawing loss and Warner Bratzler shear force decreased (P ≤ 0.05) with ageing period. Meat from heifers fed cactus diets had lower (P ≤ 0.05) proportions of oleic acid (C18:1n9c) and total MUFA, higher (P ≤ 0.05) proportions of total SFA, C15:1, C17:1, linoleic acid (C18:2n6c) and total PUFA. The control diet produced meat with the highest thiobarbituric acid reactive substances (TBARS) values compared to other diets (P ≤ 0.05) and with ageing TBARS values increased (P ≤ 0.05). Diet showed an effect (P ≤ 0.05) on sensory attributes such as overall tenderness and mouth feel with cactus diets accounting for lower scores. However, juiciness, overall tenderness, grassy and animal like attributes increased with ageing (P ≤ 0.05). Inclusion of cactus in the diet did not produce any adverse effects on meat quality, fatty acid composition, lipid oxidation and sensory quality. Therefore, it can be concluded that inclusion of cactus in Nguni heifer finisher diets up to 20% can improve meat quality.
- Full Text:
- Date Issued: 2020
- Authors: Mkhosi, Silungile
- Date: 2020
- Subjects: Meat -- Quality
- Language: English
- Type: Thesis , Masters , MSc (Animal Science )
- Identifier: http://hdl.handle.net/10353/18732 , vital:42728
- Description: The objective of the study was to determine meat quality, fatty acid (FA) composition and shelf-life stability of longissimus muscle of Nguni heifers fed incremental levels of Opuntia ficus-indica (cactus) cladodes. A total of 32 heifers aged 36 months were allocated randomly to four dietary treatments: 10% cactus, 20% cactus, commercial and control diets for 90 days. The longissimus thoracis et lumborum (LTL) samples were taken from each carcass for the determination of meat quality, retail shelf-life stability and FA composition. Diet had no effect (P > 0.05) on pH and drip display, however, there was an increase in drip display with ageing time (P ≤ 0.05). Meat colour attributes (L* a* b* and C*) were influenced by diet, with 20% cactus diet having lower L* values compared to other diets (P ≤ 0.05). During a 14-day retail display, a diet day interaction was observed for hue angle with the cactus diets having the lowest values at day 14 of display compared to the other diets (P ≤ 0.05). Differences in meat from heifers fed different diets were observed with 20% cactus accounting for significantly (P ≤ 0.05) higher levels of deoxymyoglobin and the lowest levels of oxymyoglobin. Thawing loss and Warner Bratzler shear force decreased (P ≤ 0.05) with ageing period. Meat from heifers fed cactus diets had lower (P ≤ 0.05) proportions of oleic acid (C18:1n9c) and total MUFA, higher (P ≤ 0.05) proportions of total SFA, C15:1, C17:1, linoleic acid (C18:2n6c) and total PUFA. The control diet produced meat with the highest thiobarbituric acid reactive substances (TBARS) values compared to other diets (P ≤ 0.05) and with ageing TBARS values increased (P ≤ 0.05). Diet showed an effect (P ≤ 0.05) on sensory attributes such as overall tenderness and mouth feel with cactus diets accounting for lower scores. However, juiciness, overall tenderness, grassy and animal like attributes increased with ageing (P ≤ 0.05). Inclusion of cactus in the diet did not produce any adverse effects on meat quality, fatty acid composition, lipid oxidation and sensory quality. Therefore, it can be concluded that inclusion of cactus in Nguni heifer finisher diets up to 20% can improve meat quality.
- Full Text:
- Date Issued: 2020
Investigating carcass characteristics, meat quality and ageing effects on physicochemical attributes, lipid oxidation, and degradation of muscle proteins in mature beef and dairy cull cows
- Authors: Mpala, Bukhosi
- Date: 2020
- Subjects: Meat -- Quality Dairy cattle
- Language: English
- Type: Thesis , Masters , MSc (Animal Science )
- Identifier: http://hdl.handle.net/10353/18777 , vital:42732
- Description: This study aimed to examine carcass characteristics, meat quality and postmortem ageing effects on physicochemical properties, lipid oxidation and muscle protein degradation in dairy and beef cull cows. Three cattle genotypes representing dairy {Holstein-Friesian (HF)}, beef {Bonsmara (BON)}, and a mixed purpose genotype {South Devon × Aberdeen Angus crossbreed (SD × AA)} were selected at a commercial abattoir lairage and used for this study. From each genotype, mature cows falling into the C-age class were then randomly chosen consisting of 24 HF, 31 BON and 26 SD × AA. The South African red meat classification system was used to evaluate carcass parameters, while objective measurements associated with meat quality {i.e., pH, colour (CIE L*, a*, b*), water holding capacity (WHC) and Warner-Bratzler shear force (WBSF)} were assessed in the M. longissimus thoracis et lumborum (LTL) muscle. Also, six cows were selected from each genotype within a carcass weight range of 290 ± 5 kg and fat score (FS) and conformation score (CS) of 2 and 3 respectively, and their meat was aged in a 4 ℃ chiller for 1, 7 or 14 days. At each ageing period, steaks were evaluated for pH, colour, WHC, WBSF and lipid oxidation. Furthermore, sub-samples were cut from each aged steak, vacuum-sealed, and stored in a freezer at -20 ℃ until needed for the determination of protein solubility and degradation of myofibrillar and sarcoplasmic proteins. Study results showed that the HF had a significantly (P < 0.05) lower dressing percentage than the BON and SD × AA. A total of 59% of the cull cows yielded lean carcasses, while 33% and 4% had a medium and fat subcutaneous fat score, respectively. The Holstein-Friesian recorded carcasses that had a fat score of 0 (2%) and a fat score of 1 (4%) while the Bonsmara had 20% C2, 16% C3 and 2% C4 carcasses, respectively. Most of the carcasses (78%) had a medium CS with the BON and SD × AA making up to 37% and 30%, respectively. All the measured meat quality attributes showed significant differences (P < 0.05) among the three cattle genotypes, except b*, hue angle and thawing loss. Notably, the HF recorded higher (P < 0.05) L*, a* and drip loss values but had a lower WBSF than the BON. The findings of the present study also showed that meat pH, colour traits, purge loss, lipid oxidation, cooking loss and WBSF were significantly (P < 0.05) influenced by post-mortem ageing and genotype. Except for SD × AA, WBSF only showed a significant decrease after 14 days of ageing. Moreover, significant (P < 0.05) ageing and genotype effects were observed on protein solubility and degradation of sarcoplasmic and myofibrillar proteins. One dimensional gel electrophoresis revealed the presence of several protein bands 4 Final Submission of Thesis, Dissertation or Research Report/Project, Conference or Exam Paper with molecular weights ranges of 16 - 250 kDa and 12.5 – 166.6 kDa in the myofibrillar and sarcoplasmic protein extracts, respectively. The staining intensities of some the protein bands were significantly (P < 0.05) influenced by ageing and cattle genotype. In conclusion, the present study observed that carcass characteristics and meat quality traits vary among cattle genotypes with different production use. The data also revealed that physicochemical characteristics and degradation of muscle proteins is related to both cattle genotype and postmortem ageing. It is recommended that the meat of mature cull cows be aged under vacuum conditions for up to 14 days to improve its tenderness.
- Full Text:
- Date Issued: 2020
- Authors: Mpala, Bukhosi
- Date: 2020
- Subjects: Meat -- Quality Dairy cattle
- Language: English
- Type: Thesis , Masters , MSc (Animal Science )
- Identifier: http://hdl.handle.net/10353/18777 , vital:42732
- Description: This study aimed to examine carcass characteristics, meat quality and postmortem ageing effects on physicochemical properties, lipid oxidation and muscle protein degradation in dairy and beef cull cows. Three cattle genotypes representing dairy {Holstein-Friesian (HF)}, beef {Bonsmara (BON)}, and a mixed purpose genotype {South Devon × Aberdeen Angus crossbreed (SD × AA)} were selected at a commercial abattoir lairage and used for this study. From each genotype, mature cows falling into the C-age class were then randomly chosen consisting of 24 HF, 31 BON and 26 SD × AA. The South African red meat classification system was used to evaluate carcass parameters, while objective measurements associated with meat quality {i.e., pH, colour (CIE L*, a*, b*), water holding capacity (WHC) and Warner-Bratzler shear force (WBSF)} were assessed in the M. longissimus thoracis et lumborum (LTL) muscle. Also, six cows were selected from each genotype within a carcass weight range of 290 ± 5 kg and fat score (FS) and conformation score (CS) of 2 and 3 respectively, and their meat was aged in a 4 ℃ chiller for 1, 7 or 14 days. At each ageing period, steaks were evaluated for pH, colour, WHC, WBSF and lipid oxidation. Furthermore, sub-samples were cut from each aged steak, vacuum-sealed, and stored in a freezer at -20 ℃ until needed for the determination of protein solubility and degradation of myofibrillar and sarcoplasmic proteins. Study results showed that the HF had a significantly (P < 0.05) lower dressing percentage than the BON and SD × AA. A total of 59% of the cull cows yielded lean carcasses, while 33% and 4% had a medium and fat subcutaneous fat score, respectively. The Holstein-Friesian recorded carcasses that had a fat score of 0 (2%) and a fat score of 1 (4%) while the Bonsmara had 20% C2, 16% C3 and 2% C4 carcasses, respectively. Most of the carcasses (78%) had a medium CS with the BON and SD × AA making up to 37% and 30%, respectively. All the measured meat quality attributes showed significant differences (P < 0.05) among the three cattle genotypes, except b*, hue angle and thawing loss. Notably, the HF recorded higher (P < 0.05) L*, a* and drip loss values but had a lower WBSF than the BON. The findings of the present study also showed that meat pH, colour traits, purge loss, lipid oxidation, cooking loss and WBSF were significantly (P < 0.05) influenced by post-mortem ageing and genotype. Except for SD × AA, WBSF only showed a significant decrease after 14 days of ageing. Moreover, significant (P < 0.05) ageing and genotype effects were observed on protein solubility and degradation of sarcoplasmic and myofibrillar proteins. One dimensional gel electrophoresis revealed the presence of several protein bands 4 Final Submission of Thesis, Dissertation or Research Report/Project, Conference or Exam Paper with molecular weights ranges of 16 - 250 kDa and 12.5 – 166.6 kDa in the myofibrillar and sarcoplasmic protein extracts, respectively. The staining intensities of some the protein bands were significantly (P < 0.05) influenced by ageing and cattle genotype. In conclusion, the present study observed that carcass characteristics and meat quality traits vary among cattle genotypes with different production use. The data also revealed that physicochemical characteristics and degradation of muscle proteins is related to both cattle genotype and postmortem ageing. It is recommended that the meat of mature cull cows be aged under vacuum conditions for up to 14 days to improve its tenderness.
- Full Text:
- Date Issued: 2020
The effect of feeding varying inclusion levels of velvet bean (Mucuna pruriens) seed meal on growth performance and physicochemical attributes of broiler chicken
- Authors: Mthana, Makiwa Simeon
- Date: 2020
- Subjects: Legumes Broilers (Chickens) Chickens -- Feeding and feeds
- Language: English
- Type: Thesis , Masters/Doctoral , MSc (Animal Science )
- Identifier: http://hdl.handle.net/10353/12032 , vital:39129
- Description: This study was conducted to determine the effect of feeding varying inclusion levels of velvet bean (Mucuna pruriens) seed meal (VBSM) on growth performance and physicochemical attributes of broiler chicken. Mucuna pruriens seed is an indigenous legume seed commonly found in tropical and sub-tropical areas; however, it can also be planted and cultivated. It is a viable source of dietary protein with an average concentration of 33.4%. Soybean is expensive. In addition, the South African production levels do not meet the current demand; hence the majority of soybean oilcake is imported. Recently, consumers have been conscious of the quality of chicken meat from both local and international producers. Therefore, there is a need to explore velvet bean that can grow in poorly fertilised and low rainfall areas. The study was conducted at Fort Cox Agriculture and Forestry Training Institute. One hundred and twelve (112) Cobb broilers were used, with an average weight of 45.2g. Four diets were formulated to be iso-caloric and iso-nitrogenous comprising velvet beans at 0, 10, 15 and 20 % (T1, T2, T3 and T4). The broilers were reared for 42 days with 35 days on experimental diets. Feed intake, body weight gain, feed conversion ratio, mortality, final body weight, carcass weight, and dressing percentage were determined. At day 42, twenty birds per treatment were randomly selected and fasted for five hours with water offered ad libitum. After slaughter the meat pH24, colour (L*, a*, b*), Warner-Bratzler shear force (WBSF), thawing loss (TL), and cooking loss (CL) measurements were performed on 80 breast and 80 thigh muscles. The data for growth performance and physicochemical parameters was analysed using General Linear Model (GLM) procedure of SAS (SAS, 2006), mean separation was done using LSD test option of SAS. Daily feed intake, body weight gain, final weight and carcass weight of broilers from T1 were significantly higher (P < 0.05) from other iii treatments. Daily feed intake (DFI), and body weight gain (BWG) in T1 were also higher (P < 0.05) in both phase 1 and phase 2 compared to other treatments. Feed conversion ratio (FCR) was not influenced by diets (P > 0.05). High (P < 0.05) mortality was observed on broilers fed diet with 0% VBSM compared to those fed diets comprising of VBSM. The diets did not have an effect (P > 0.05) on thigh meat pH24, lightness, redness, and WBSF. Cooking loss (25.69%) was higher (P < 0.05) in thigh meat of broilers fed the control diet. Breasts shear force (14.20) was higher in T4. Cooking loss of breast meat from broilers on T1 and T2 was higher (P < 0.05) than those from other treatments. Breast meat colour (P > 0.05) was not influenced by diets. It can be concluded that the VBSM has an effect on feed intake, growth performance and mortality of broilers, except on FCR and dressing percentage. It was also concluded that the VBSM can be included in broiler diets up to the level of 15% without negatively affecting the quality of meat.
- Full Text:
- Date Issued: 2020
- Authors: Mthana, Makiwa Simeon
- Date: 2020
- Subjects: Legumes Broilers (Chickens) Chickens -- Feeding and feeds
- Language: English
- Type: Thesis , Masters/Doctoral , MSc (Animal Science )
- Identifier: http://hdl.handle.net/10353/12032 , vital:39129
- Description: This study was conducted to determine the effect of feeding varying inclusion levels of velvet bean (Mucuna pruriens) seed meal (VBSM) on growth performance and physicochemical attributes of broiler chicken. Mucuna pruriens seed is an indigenous legume seed commonly found in tropical and sub-tropical areas; however, it can also be planted and cultivated. It is a viable source of dietary protein with an average concentration of 33.4%. Soybean is expensive. In addition, the South African production levels do not meet the current demand; hence the majority of soybean oilcake is imported. Recently, consumers have been conscious of the quality of chicken meat from both local and international producers. Therefore, there is a need to explore velvet bean that can grow in poorly fertilised and low rainfall areas. The study was conducted at Fort Cox Agriculture and Forestry Training Institute. One hundred and twelve (112) Cobb broilers were used, with an average weight of 45.2g. Four diets were formulated to be iso-caloric and iso-nitrogenous comprising velvet beans at 0, 10, 15 and 20 % (T1, T2, T3 and T4). The broilers were reared for 42 days with 35 days on experimental diets. Feed intake, body weight gain, feed conversion ratio, mortality, final body weight, carcass weight, and dressing percentage were determined. At day 42, twenty birds per treatment were randomly selected and fasted for five hours with water offered ad libitum. After slaughter the meat pH24, colour (L*, a*, b*), Warner-Bratzler shear force (WBSF), thawing loss (TL), and cooking loss (CL) measurements were performed on 80 breast and 80 thigh muscles. The data for growth performance and physicochemical parameters was analysed using General Linear Model (GLM) procedure of SAS (SAS, 2006), mean separation was done using LSD test option of SAS. Daily feed intake, body weight gain, final weight and carcass weight of broilers from T1 were significantly higher (P < 0.05) from other iii treatments. Daily feed intake (DFI), and body weight gain (BWG) in T1 were also higher (P < 0.05) in both phase 1 and phase 2 compared to other treatments. Feed conversion ratio (FCR) was not influenced by diets (P > 0.05). High (P < 0.05) mortality was observed on broilers fed diet with 0% VBSM compared to those fed diets comprising of VBSM. The diets did not have an effect (P > 0.05) on thigh meat pH24, lightness, redness, and WBSF. Cooking loss (25.69%) was higher (P < 0.05) in thigh meat of broilers fed the control diet. Breasts shear force (14.20) was higher in T4. Cooking loss of breast meat from broilers on T1 and T2 was higher (P < 0.05) than those from other treatments. Breast meat colour (P > 0.05) was not influenced by diets. It can be concluded that the VBSM has an effect on feed intake, growth performance and mortality of broilers, except on FCR and dressing percentage. It was also concluded that the VBSM can be included in broiler diets up to the level of 15% without negatively affecting the quality of meat.
- Full Text:
- Date Issued: 2020
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