Browsing by Author "Roos, Tenisha"

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    The effect of age and sex on meat quality characteristics of blue wildebeest (Connochaetes taurinus)
    (Stellenbosch : Stellenbosch University, 2020-03) Roos, Tenisha; Hoffman, Louwrens C.; Strydom, P. E.; Stellenbosch University. Faculty of AgriSciences. Dept. of Animal Sciences.
    ENGLISH ABSTRACT: Selective culling has become a popular practice for intensive to semi-extensive wildlife farms. However, some game farmers remain hesitant to cull surplus, older cows and young heifers and bulls for meat production due to the uncertainties regarding the meat quality of these animals. Therefore, this research aimed to quantify the effect of age and sex on various carcass characteristics and meat quality parameters of blue wildebeest (Connochaetes taurinus) meat to provide baseline data for the Wildlife industry of South Africa. The latter was achieved by collecting data of the carcass characteristics, including muscle-, internal- and external offal yields, as well as the body condition score (BCS) of the dressed carcasses. The physical quality (ultimate pH (pHU), drip- and cooking loss, colour and shear force) and chemical composition (moisture, protein, fat and ash content) of six muscles (Longissimus thoracis et lumborum (LTL), biceps femoris (BF), semimembranosus (SM), semitendinosus (ST), infraspinatus (IS) and supraspinatus (SS)) of blue wildebeest were also determined. The study included a total of 32 blue wildebeest, comprising of two trials. The first trial consisted of 24 blue wildebeest females who were categorised into three age groups (1.5-, 4.5- and >6.5-years old). The trial included eight females of each age group which were culled from a semi-extensive production system in the Central Bushveld region located on the outskirts of the Modimolle region in the Limpopo, South Africa. When the effect of age on carcass yields was investigated, the 4.5-year old cows had the heaviest dead weights (203.63 ± 9.54 kg), total internal- (55.84 ± 2.87 kg) and total offal weights (88.83 ± 5.75 kg). However, no differences were recorded between the cold carcass weights (100.15 ± 10.01 kg >6.5-year old; 105.45 ± 6.82 kg 4.5-year old), dressing percentage (53.10 ± 3.55 % >6.5-year old; 51.78 ± 1.99 % 4.5-years old), total external offal weights (33.29 ± 2.26 kg >6.5-years old; 33.38 ± 2.84 kg 4.5-years old), individual muscle weights, as well as for the BCS of the two older age groups. The 1.5-year old heifers were associated with the lightest carcass yields and lower BCS in comparison to the older age groups. A significant age effect was also observed for the physical parameters measured for the six muscles of blue wildebeest females. The oldest age group was associated with the highest pHU values for all six muscles, and for some muscles (LTL, ST and IS) the pHU was higher than 5.9 which could result in dark-firm-dry (DFD) meat. Many of the muscles of the two older age groups showed tendencies of lower drip loss than the heifers, while the heifers exhibited higher cooking loss for the LTL, BF and ST muscles than the >6.5-year old cows. An age effect was observed for the shear force values of the six muscles. The heifers had significantly lower shear force values for the LTL, IS and SS muscles than the 4.5-year old cows. The muscles of the 4.5-year old cows exhibited more vivid colour (high chroma-, a* and b* values) than the other age groups, while the youngest animals had significantly lighter (high L* values) and less red (high hue-angle) muscles. Furthermore, age had little effect on the basic chemical composition of the muscles investigated. The heifers had higher moisture content in the ST, IS and SS muscles than the older animals, but the differences were less than 1.5 %. Age had a negligible effect on the protein content and the ash content of the muscles of the blue wildebeest females. The oldest cows (>6.5-years old) had higher fat content in the LTL (1.7 ± 0.14 %), BF (1.7 ± 0.09 %) and SS (2.1 ± 0.15 %) muscles than the younger females, however, the differences were negligible (<0.5% differences). The second trial included eight additional 1.5-year old blue wildebeest bulls that were compared to the 1.5-year old heifers from the first trial. Sexual dimorphism was observed for most of the carcass yields (dead-, cold carcass weight, dressing percentage, total offal yields, muscles weights and the BCS) for which the bulls recorded heavier weights than the heifers. Sex also had a significant effect on the physical quality of the six muscles investigated in this trial. The bulls had higher pHU values for four of the muscles than the heifers for which two muscles (LTL and ST) exhibited pHU >5.9 (DFD meat). The heifers had higher drip loss in three muscles (LTL (2.4 ± 0.61 %), SM (3.6 ± 1.05 %) and SS (1.5 ± 0.25 %)) than the bulls, while only two muscles (BF (42.0 ±1.25 %) and ST (42.1 ± 0.91 %)) of the heifers showed higher cooking loss than the bulls. Sex had little effect on the shear force values of the six muscles of the bulls and heifers. Furthermore, the muscles located in the hindquarters of the bulls were darker (low L* values and high myoglobin content (g/100g)) and redder (lower hue-angle values) than that of the heifers. The BF and ST muscles of the bulls were associated with lower metmyoglobin- (MMb) and higher oxymyoglobin (OMb) percentages than the heifers. With regards to the chemical composition of the six muscles of the bulls and heifers, the heifers exhibited higher moisture content and lower protein content in the SM and ST muscles (<1 % difference). Furthermore, sex had a negligible effect on the fat- and ash content of the muscles of bulls and heifers. Therefore, it was concluded that the older surplus blue wildebeest cows and young blue wildebeest bulls can be harvested for meat production due to their high carcass yields and desired physical- and chemical meat quality of the six muscles (excluding those exhibiting DFD characteristics) investigated.