Louw C. Hoffman

Comparison of six crossbred lamb types: sensory, physical and nutritional meat quality characteristics

The effect of crossbreeding on lamb meat quality was examined on the M. longissimus dorsi and M. semimembranosus of South African lamb breed combinations. The lambs were sired by Dormer (D) and Suffolk (S) rams and born to Merino (M), Dohne Merino (DM) and SA Mutton Merino (SAMM) ewes to give six breed combinations. Ratings of sensory attributes on the M. semimembranosus of the different lamb breed combinations were obtained from a trained descriptive panel. The moisture, total lipids, protein, ash, mineral content and fatty acid composition of the M. semimembranosus were also obtained. Physical parameters measured on the M. longissimus dorsi were: pH(48), drip loss, cooking loss and Warner-Bratzler shear force (WBS). Breed did not have a significant effect (P>0.05) on the sensory quality of lamb, except for D×SAMM lambs which only showed a significantly higher (P⩽0.05) initial juiciness compared to S×M. However, breed had a significant effect on pH(48), WBS, protein content and the fatty acid and mineral composition.

The yield and nutritional value of meat from African ungulates, camelidae, rodents, ratites and reptiles

The current knowledge of the yield and nutritional (proximate and fatty acid) composition of meat derived from African ungulates, camelidae, rodents, ratites and reptiles is reviewed. Although most of the species discussed give low cholesterol levels consistent with their low meat lipid contents, the tegu lizard gives a very low level (18.2mg/100g tissue). The fatty acid profiles of the various species all have low saturated fatty acids and high polyunsaturated fatty acids resulting in favourable saturated to polyunsaturated fatty acid ratios. Although the springbok, camel, ostrich and crocodile are marketed and exported to sophisticated markets, the rodents are the species that show most promise in becoming large commercial commodities. Not only is their meat desirable and nutritional, but they are also highly adaptable to extensive and intensive production systems.

Meat quality characteristics of springbok (Antidorcas marsupialis). 2: Chemical composition of springbok meat as influenced by age, gender and production region.

The effects of age, gender and production region on the chemical, mineral and amino acid composition of the M. longissimus dorsi (LD) muscle of springbok were investigated. There was a significant gender(∗)region interaction for protein content - for the four production regions it varied between 18.80 and 21.16g/100g. The intramuscular fat (IMF) content of the LD muscle varied between 1.32 and 3.46g/100g. Females (3.13±0.28g/100g) had a higher (P<0.05) fat content than males (1.35±0.08g/100g). The IMF content of the adult (2.45±0.26g/100g) and sub-adult (2.50±0.28g/100g) categories was higher (P<0.05) in comparison to that of the lambs (1.32±0.11g/100g). An inverse correlation was noted between the IMF and moisture content (r=-0.49, P<0.001) of the meat. The two main amino acids were glutamic and aspartic acid, which contributed 2.47-2.74 and 2.31-2.54g/100g of dry matter, respectively. Phosphorous was the predominant mineral in the LD muscle (122.92-159.78mg/100g of dry matter), followed by potassium (119.44-131.25mg/100g of dry matter) and calcium (6.57-145.18mg/100g of dry matter). Production region had a significant effect on the mineral and amino acid composition of the meat, while the effects of age and gender were found to be insignificant.

Prediction of the chemical composition of freeze dried ostrich meat with near infrared reflectance spectroscopy

Near infrared reflectance spectroscopy (NIRS) was used to predict the chemical composition of freeze-dried ostrich meat samples. Tenderloin (M. ambiens), big drum (M. iliofibularis) and fan fillet (M. gastrocnemius) samples (n=160) were included in the study. Samples were minced, freeze-dried and analysed according to standard laboratory procedures for ash, dry matter (DM), crude protein (CP) and fat content. Samples were scanned (1100-2500 nm) and partial least-square regression (PLSR) was used to predict the chemical composition. Multiple correlation coefficients (r) and standard errors of calibration (SEC) for the chemical analysis of freeze-dried ostrich meat were: ash (0.72; 0.29%); DM (0.72; 1.01%); CP (0.98; 0.55%); and fat (0.99; 0.29%). The r values for the validation set and the standard error of performance (SEP) for the different constituents were: ash (0.71; 0.23%); DM (0.84; 0.72%); CP (0.97; 0.64%); and fat (0.99; 0.18%). Calibrations were accurate for CP and fat.

Production of salami from beef, horse, mutton, Blesbok (Damaliscus dorcas phillipsi) and Springbok (Antidorcas marsupialis) with bacteriocinogenic strains of Lactobacillus plantarum and Lactobacillus curvatus

Lactobacillus plantarum 423, producer of bacteriocin 423, Lactobacillus curvatus DF38, producer of curvacin DF38, and a bacteriocin-negative mutant of L. plantarum 423 (423m) were evaluated as starter cultures in the production of salami from beef, horse, mutton, Blesbok (Damaliscus dorcas phillipsi) and Springbok (Antidorcas marsupialis). Growth of L. plantarum 423 and L. curvatus DF38 was best supported in Blesbok salami, as revealed by the highest growth rate during sweating, cold smoking and maturation, and final cell numbers after 70 days (1×10(8) and 5×10(7)cfu/g, respectively). Growth of Listeria innocua was the best suppressed in Blesbok salami fermented with L. plantarum 423 and L. curvatus DF38. Growth of L. innocua in horse salami was best suppressed when fermented with L. curvatus DF38. The final pH of salami fermented with L. plantarum 423 and L. plantarum 423m was slightly lower (4.4) compared to the pH of salami produced with L. curvatus DF38 (pH 4.7). No significant differences (P>0.05) were recorded by a trained sensory taste panel amongst the three starter cultures regarding colour and venison like aroma. Horse, Blesbok and Springbok salami were rated significantly higher (P⩽0.05) in salami flavour than mutton salami, which was rated the lowest for this attribute. Blesbok salami was rated the highest for sour meat aroma, while beef salami was rated the lowest. Springbok salami was rated the highest in terms of oily mouth feel. Beef salami had the most compact structure and horse salami the softest structure of all meat types fermented. In general, salami produced with L. plantarum 423 yielded the best sour meat aroma, colour, texture, venison like flavour, sour meat flavour and oily mouthfeel and is considered superior to the L. plantarum mutant (strain 423m) and L. curvatus DF38.

Zoonoses: a potential obstacle to the growing wildlife industry of Namibia

Zoonoses, which account for approximately 75% of emerging human infectious diseases worldwide, pose a re-emerging threat to public health. With an ever-increasing interrelationship between humans, livestock and wildlife species, the threat to human health will rise to unprecedented levels. Wildlife species contribute to the majority of emerging diseases; therefore, there is an urgent need to define control systems of zoonoses of wildlife origin but very little information exists. In this review, we examine prevalent zoonotic infections reported in Namibia between 1990 and 2009 and assess their potential impact on the growing wildlife industry. A wide spectrum of zoonotic diseases was confirmed in both livestock and wildlife species, with rabies and anthrax cases being over-represented and also showing the widest species distribution. Whilst vaccination and ante-mortem inspection against these diseases may curb infected livestock species from entering the human food chain, such practices are difficult to implement in free-ranging wildlife species. In this context, there is a need to improve existing control measures and/or develop novel and better interventional strategies to reduce the threat of this re-emerging global problem. This review provides the basis for initiating a multidisciplinary evidence-based approach to control zoonoses in countries with thriving wildlife and game farming.

Characteristics of impala (Aepyceros melampus) skeletal muscles

The aim of this study was to determine citrate synthase (CS), phosphofructokinase (PFK) activities and myosin heavy chain (MHC) isoform contents in four muscle groups (semimembranosus (S), deltoideus (D), longissimus lumborum (LL), and psoas major (PM)) of impala (n=6). All four muscle groups expressed predominantly MHC IIa (means of 55±22-93±12%). MHC IIx was only expressed in D. In D, positive correlations were found between MHC I and age (r=0.93; P<0.05) and the weight of the animals (r=0.94; P<0.01). PFK (means of 175±179-374±181), CS (means of 100±23-126±38 μmol/min/gdw) and MHC content indicated that energy provision in the impala is produced to a large extent via oxidative pathways and fibre types vary with animal characteristics.

Physical meat quality characteristics of hot-deboned ostrich (Struthio camelus var. domesticus) Muscularis gastrocnemius, pars interna during post-mortem aging

There is a risk of shortening and toughening with hot-deboning of muscles. However, with refrigerated aging this phenomenon may be negated. Vacuum-packed hot and cold-deboned ostrich Muscularis gastrocnemius, pars interna were stored for 21 d at 4°C to investigate the effects of hot-deboning on quality characteristics of ostrich meat during refrigerated storage. Muscle pH did not differ (P>0.05) between hot and cold-deboned muscles during storage. Hot-deboning caused (P<0.0001) more purge in the vacuum packages of the hot-deboned muscles (1.83±1.31%) than in the cold-deboned muscles (0.67±075%) during the 21-d aging period. Hot-deboned muscles were tougher (P<0.05) than cold-deboned muscles from 24h up to 5 d. Although hot-deboning caused muscles to be tougher than cold-deboned muscles, with aging at 4°C beyond 5 d this toughness was found to be insignificant.

Effect of season and gender on the physical and chemical composition of black wildebeest (Connochaetus gnou) meat.

The aim of this study was to investigate the effect of different seasons and gender on the physical and chemical composition of black wildebeest (Connochaetus gnou) meat. Twenty-six black wildebeest were harvested at Maria Moroka Nature Reserve, in the Free State Province, South Africa, during winter, spring and autumn. Mean body and carcass weight did not differ (P > 0.05) between either seasons or genders. However, dressing percentage was higher (P < 0.05) for males (53.19%) than for females (50.65%). Initial (pH45min) and ultimate pH (pH24h) of the M. longissimus dorsi differed (P > 0.05) between seasons, whereas differences (P < 0.05) in temperature of carcasses measured 24 h post-mortem could be ascribed to differences in ambient temperature. Meat from animals harvested during spring (5.52 and 39.63%) had a higher (P ≤ 0.05) drip and cooking loss compared to those harvested in winter (2.27 and 34.59%) and autumn (3.61 and 33.88%). Meat was the most (P < 0.05) tender during autumn (2.27 kg/1.27 cm diameter) while that of females was more tender than the males. The colour of the meat was darker in winter (L*-value of 28.90) compared to spring (34.08) and autumn (32.91). Protein content of the m. longissimus dorsi was lowest (P < 0.05) in spring (20.45%). Lipid content was highest (P < 0.05) in winter (1.22%) and also lowest (P < 0.05) in males (0.90). Although season has significant Influences on some physical and chemical characteristics of meat from the black wildebeest, the extent of these differences does not necessitate a different classification system.

Physical and chemical properties of male and female mountain reedbuck (Redunca fulvorufula) meat

The influence of gender on the physical and chemical properties of the M. longissimus dorsi et lumborum of mountain reedbuck (Redunca fulvorufula) was examined. The mean live weights of ten male (28.58 kg) and nineteen female (30.58 kg) mountain reedbuck did not differ (P > 0.05),and the mean cold carcass weight was 16.36 kg for both genders. Gender had no influence (P > 0.05) on any of the physical characteristics (pH, drip loss, cooking loss, shear force, colour) investigated. For the proximate chemical analysis of the M. longissimus dorsi et lumborum muscle, the effect of gender was only significant for the protein content, where the females (24.51%) displayed a higher percentage of protein compared to the males (23.68%). Neither the amino acid nor the mineral content differed significantly between the two genders. Glutamic acid (11.35 g/100 g) was the most abundant amino acid, followed by aspartic acid (2.94 g/100 g), glycine (0.86 g/100 g) and serine (0.66 g/100 g). The mineral content of mountain reedbuck indicated that meat derived from this species is high in phosphorus (206.47 mg/100 g), high in iron (4.19 mg/100 g), a source of zinc (1.80 mg/100 g), and low in sodium (4.19 mg/100 g). No significant differences between the genders for total saturated fatty acids (38.09%), total mono-unsaturated fatty acids (18.04%) or total polyunsaturated fatty acids (43.74%) were noted. The mean polyunsaturated:saturated fatty acid ratio for mountain reedbuck was 1.15 and the mean n-6:n-3 PUFA ratio 2.08. The extent of the influence of gender on physical and chemical characteristics of meat was found to be of limited practical value.