The objective of this study was to determine time budgets, blood urea content, total protein and body condition score as adaptive responses to seasonal dynamics by breeding Nguni cows and heifers reared on a sweetveld. Twenty four clinically healthy Nguni cows and heifers were selected for the study. The animals were grouped according to their parities namely: Parity 1 (n=5), Parity 2 (n=5), Parity 3-6 (old cows) (n=9) and in-calf heifers (n=5). Two separate experiments were conducted and running concurrently. In the first experiment time budgets (time spent walking, grazing, lying down, drinking water and browsing) of the cows and heifers were monitored for two consecutive days once a month, while in the second experiment blood samples were collected from the coccygeal vein once a month during weighing. Body condition scores were also determined during weighing times. Heifers maintained significantly (p0.05) of both blood urea nitrogen (BUN) (7.5±0.39 mmol/l) and TP (80.7±1.19 g/l) in November. All the animals had the least BUN levels in January (1.93±0.18 mmol/l) while the highest total protein (TP) (82.1±1.08 g/l) was recorded in February. All the animals showed distinct (p0.05) in most behavioural attributes in the cool-wet season. Heifers spent significantly (p0.05) body condition scores, amount of time spent browsing and drinking water. On the other hand, heifers (14.7±1.50%) and first parity cows (13.9±1.50%) traded-off most (p<0,05) of their time walking during the cool-dry season. Similarly heifers spent more time browsing (6.4±0.62%) forage plants (p<0.05) than all the cows during the cool-wet season. Grazing (r = 0.17) and standing (r = -0.18) were correlated (p<0.05) with all the behavioural attributes measured in this environment. It was concluded that seasonal dynamics in trade-off behaviour through time budgeting, maintenance of BUN and TP were necessary for the Nguni cows and heifers to maintain their body condition scores within a narrow range throughout the four seasons.

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<p>Historically, the meat industry has struggled to provide consumers with consistent beef tenderness. Various post-harvest technologies have been used in industry; however, there is still a need to develop a natural and safe post-harvest processing system that can be used to create consistently tender products for consumers. In addition to postmortem aging being a time-consuming process, literature has suggested that it is not a sufficient method to achieve tenderization in certain cull cow muscles. This has resulted in the large supply of cull cow beef to be underutilized due to its inferior quality, specifically tenderness. Applying a combination of mechanical tenderization with additional postmortem aging may be an effective strategy to overcome deficiencies in beef tenderness. Recent studies have found that tumbling without brine addition can be successful at improving instrumental tenderness and consumer liking of tenderness of fresh beef loin. The physical disruptions of muscles, which likely occur during tumbling, may enhance activity of proteolytic enzymes and thus induce more tenderization. The overall objective of this thesis was to investigate the effects of fresh beef tumbling methods and postmortem aging times on the tenderness and proteolysis of loin muscles from both A maturity cattle and cull cows.</p> <p>The first chapter of this thesis is a literature review that will address the factors affecting tenderness and the methods used by the industry to improve tenderness, specifically focusing on meat tumbling and cull cow beef. The second chapter is a study that investigated the effects of fresh beef tumbling at different postmortem times on meat quality attributes and proteolytic features of loins. The results from this study suggest that early postmortem tumbling coupled with aging can synergistically impact the improvements of beef loin tenderness and proteolysis, shortening the necessary aging period. The third and final chapter of this thesis is a study that aimed to determine the effect of fresh beef tumbling and postmortem aging on the quality and proteolysis of loins from cull cows. The results from this study indicate that aging would be effective at improving the quality and palatability of cull cow beef loins, although tumbling could improve consumer liking of tenderness at earlier postmortem times.</p>

The instrument grading assessments for the NBQA-2011 evaluated seasonal trends of beef carcass quality and yield attributes over the course of the year. One week of instrument grading data—HCW, gender, USDA QG, and YG factors—were collected every other month (n = 2,427,074 carcasses) over a 13-month period (November 2010 through November 2011) from four beef processing corporations, encompassing 17 federally inspected beef processing facilities, to create an overview of carcass quality and yield attributes and trends from carcasses representing approximately 8.5% of the U.S. fed steer and heifer population. Mean yield traits were: YG (2.86), HCW (371.3 kg), FT (1.19 cm.), and LM area (88.39 cm^2). The YG distribution was YG 1 (15.7%), YG 2 (41.0%), YG 3 (33.8%), YG 4 (8.5%), and YG 5 (0.9%). Distribution of HCW was <272.2 kg (1.6%), 272.2 kg to 453.6 kg (95.1%), ≥453.6 kg (3.3%). Monthly HCW means were: November 2010 (381.3 kg), January 2011 (375.9 kg), March 2011 (366.2 kg), May 2011 (357.9 kg), July 2011 (372.54 kg), September 2011 (376.1 kg), and November 2011 (373.5 kg). The mean FT for each month was November 2010 (1.30 cm), January 2011 (1.22 cm), March 2011 (1.17 cm), May 2011 (1.12 cm), July 2011 (1.19 cm), September 2011 (1.22 cm), and November 2011 (1.22 cm). The mean marbling score was Small49. USDA QG distribution was Prime (2.7%), Top Choice (22.9%), Commodity Choice (38.6%), and Select (31.5%). Interestingly, from November to May, seasonal decreases (P < 0.001) in HCW and FT were accompanied by increases (P < 0.001) in marbling. These data present the opportunity to further investigate the entire array of factors that determine the value of beef. Datasets utilizing the online collection of electronic data will likely be more commonly used when evaluating the U.S. fed steer and heifer population in future studies. These data indicate the wide array of carcasses produced by the beef cattle industry, and how the frequency of both YG and QG traits change from month-to-month.

The main objective of the current study was to determine the effect of distance travelled (DT), lairage duration (LDhr) and animal-related factors (animal class, breed, sex) on pre-slaughter stress indicators, carcass characteristics, nanostructure and technological properties of beef. The study was conducted in an Eastern Cape abattoir under the Buffalo City District Municipality. Six genotypes of cattle (Beefmaster, Bonsmara, Brahman, Holstein-Friesian, Non-descript and Nguni) brought for slaughter at the abattoir on different days were used in the study. Slaughter weight (SWT), warm and cold carcass weight (WCW and CCW), fatness and conformation of each animal were measured and recorded. Representative samples of blood plasma and meat quality from the Muscularis thoracis et lumborum (LTL) were collected at slaughter and 24 hours after slaughter, respectively. Heat shock proteins 70kDa (HSPA1A), glucose (GLU), cortisol (CORT), creatine kinase (CK) and lactate dehydrogenase (LDH) were determined from the blood plasma. The representative LTL muscle was used to determine ultimate pH (pHu), lightness (L*), redness (a*), yellowness (b*), meat temperature (Tm), Warner Bratzler Shear Force (WBSF) and histological structure of beef. There were significant effects of distance on pHu, Tm, a*, b*, TL%, CK and LDH. Pearson correlations were observed between distance travelled (DT), creatine kinase (CK), lactate dehydrogenase (LDH), ultimate pH (pHu), colour coordinates (L*, a* and b*) and Warner Bratzler Shear Force (WBSF). Principal component analysis (PCA) revealed that the 1st (pHu), 2nd (Tm) and 3rd (L*) principal components were the critical meat quality attributes. Positive relationships between carcass weights and beef quality characteristics for bovine cattle where the cumulative percentage of the first six principal component`s (PC`s) (SWT, WCW, CCW, DP, pHu and Tm contributed to 93.4 % of the total variance. Significant correlation coefficients between DT (r = 0.15), LDhr (r = 0.29), Ta (r = -0.52), Tm (r = 0.26), L* (r = 0.33), a* (r = 0.32) and WBSF (r = -0.49) were observed. Meat from Brahman (BR), Non-descript (ND) and Nguni (NG) cows had visible skeletal muscle fibres which were thin and long indicating improved tenderness of beef. Exposing animals to longer hours of transportation did not only reduce glucose levels but also increased the expression of HSPA1A and levels of cortisol. The CK and LDH were not related to beef quality. Therefore, CK and LDH can be used as indicators of animal welfare in slaughter cattle but cannot be used to predict the quality of meat. Bulls were the heaviest, although heifers had the highest dressing percentage than cows. Furthermore, the nanostructure of beef indicated that heifers had the best muscle fibres, sarcomere length and visible intercalated discs. The observed nanostructures of Nguni genotype are an indication of tender meat. Beef from heifers of Nguni had visible and tender meat with traces of intramuscular fat while males had shorter sarcomere length and tougher meat.