The effect of beef production system on proximate composition and fatty acid profile of three beef muscles

In this study the effects of animal age combined with feeding regime and the utilisation of a beta-agonist (within a grain-fed system) on proximate composition and fatty acid profile of M. longissimus lumborum (LL), M. biceps femoris (BF), and M. semitendinosus (ST) were determined. Eighty Bonsmara steers consisting of A-age (0 permanent incisors) grain-fed (AC) and grain-fed supplemented with a beta-agonist, zilpaterol (AZ) (n = 20) grass-fed AB-age (1 - 2 permanent incisors; AB) (n = 20), and B-age (3 - 6 permanent incisors; B) (n = 20) animals were used. These four groups are representative of cattle slaughtered in South Africa and were treated as four production systems. The chemical composition of all three muscles showed that zilpaterol increased protein and reduced muscle fat contents of meat. All the muscles of both grass-fed groups (AB and B) had significantly higher content of certain desirable fatty acids (FAs) such as conjugated linoleic acid (CLA), omega-3 (n-3) FAs, branched chain saturated phytanic acid, and a lower omega-6/omega-3 (n-6/n-3) ratio than the two grain-fed groups (AC and AZ). The FA composition of grain-fed beef muscle was generally not influenced by the use of zilpaterol except for a tendency towards higher n-6 polyunsaturated fatty acid (PUFA) in beta-agonist produced beef. This was mainly due to higher levels of linoleic acid in LL and ST muscles and higher CLA in BF muscle of AZ animals. Phytanic acid was also higher in BF muscle of the AZ group compared to AC. Differences in animal age among grass-fed animals (AB vs. B) had minimal effect on FA composition of grass-fed beef. We can conclude that differences in FA composition of the three muscles are influenced mainly by feeding regime and less by differences in production factors within feeding regimes.Keywords: Animal age, grain feeding, grass feeding, zilpatero

Effects of short and extended fasting periods and cattle breed on glycogenolysis, sarcomere shortening and Warner-Bratzler shear force

The effects of short (three hours) and extended (24 hours) feed withdrawal periods and three cattle breeds on muscle energy metabolism, sarcomere length, and meat quality were investigated. Brahman (Br), Nguni (Ng), and Simmental (Sm) bulls were subjected to ante-mortem feed withdrawal of three hours (Br3, n = 10; Ng3, n = 10; and Sm3, n = 10) or 24 hours (Br24, n = 10; Ng24, n = 10; and Sm24, n = 10). M. longissimus was used as the reference muscle for sampling. pH, and temperature was recorded at 1, 2, 3, 6, 9, and 24 hours post mortem. Samples for energy metabolites were removed at 3, 6, 9 and 24 hours post mortem. Glycogen, glucose-6-phosphate and creatine phosphate concentration were determined at each time interval as glycosyl units after hydrolysis. Samples to determine sarcomere length were removed at one and three days post mortem. Homogenates of the samples were placed under a 31,000 magnification microscope and sarcomere lengths were measured. Warner-Bratzler shear force (WBSF) was measured with an Instron meter at 1, 7 and 14 days post mortem. Glycogen was lower for Br24 and Ng24. There were no differences in glucose-6-phosphate, rate of creatine phosphate decline, average sarcomere length, or WBSF for Br24 and Ng24 compared with Br3 and Ng3. There were no differences for WBSF between Br3, Ng3 and Sm3. Glycogen concentration was higher for Sm24 compared with Sm3; glucose-6-phosphate was lower for Sm24 compared with Sm3; and the rate of creatine phosphate decline was higher for Sm24 compared with Sm3. Average sarcomere length was shorter and WBSF was higher for Sm24 compared with Sm3. The effect of prolonged ante-mortem feed withdrawal on tenderness is breed specific. Warner-Bratzler shear force was affected significantly by an extended feed withdrawal period in Simmental cattle only.Keywords: Acidification, creatine phosphate depletion, fasting, hypometabolism, meat tendernes

Influence of feeding systems on selected beef quality and sensory attributes

Feeding systems and other factors associated with processing influence meat quality, and therefore sensory attributes. This study was conducted to assess the meat quality attributes of young grain-fed and older grass-fed steers that mostly affect consumer acceptability of beef. Eighty Bonsmara steers consisting of 20 each of A-age (0-tooth) grain-fed (AC) and grain-fed supplemented with zilpaterol (AZ), 20 each of grass-fed AB (1-2 teeth) and B-age (3 - 6 teeth) animals were used. This combination represented the typical feeding systems of South Africa and other countries using similar classification systems, therefore describes the typical feeding systems of the South African beef industry. The longissimus lumborum (LL), semitendinosus (ST), and biceps femoris (BF) muscles were tested for colour, moisture properties, lipid oxidation and sensory attributes. It was found that diet in combination with animal age influenced meat colour. Muscles of the older grass-fed steers were generally darker and duller (darker red) compared to muscles of young grain-fed animals. Moisture loss was consistently higher in zilpaterol supplemented meat samples compared to the feedlot controls, while muscles of the grass-fed animals had lower moisture loss. A sensory panel clearly distinguished between cuts of grain-fed (AZ and AC) and grass-fed carcasses (AB and B) on the grounds of flavour characteristic. The AB and B cuts scored higher for grassy, animal-like and rancid flavour overtones and lower for roasted flavour and sourness than AZ and AC grain-fed cuts. This indicated that typical flavours related to diet define expected eating quality. Keywords: age, grain, grass, meat quality, zilpatero

Relationships between production and product traits in subpopulations of Bonsmara and Nguni cattle

Ninety bull calves of five Bonsmara strains, viz. Edelheer (E), T-49 (T), Wesselsvlei (W), Roodebos (R) and Belmont Red (BR), and two Nguni sub-populations, viz. Bartlow (B) and non-Bartlow (NB), were fattened under intensive feeding conditions and serially slaughtered at four different slaughter weights. Phylogenetic relationships between the five Bonsmara strains and between the two Nguni subpopulations were determined by means of blood typing. Growth performance, carcass characteristics and meat quality characteristics were compared between the sub-populations of each breed. Genetic distances between the Bonsmara animals confirmed the existence of five genetic subpopulations with variation in genetic distances between them. The genetic distance between the two Nguni subpopulations was very small, indicating genetic similarity. Means for production and product characteristics were adjusted for mean subcutaneous fat percentage by means of analysis of covariance. T gained weight faster and more efficiently on a live and carcass weight basis than the other Bonsmara groups, while B gained carcass and muscle weight more efficiently than NB. T had proportionally more meat in the high-priced cuts of the carcass than W. Muscle of the W line had a higher ageing potential (measured as myofibrillar fragmentation; MFI) than T, resulting in higher tenderness scores for W. Similarly, B had higher MFI for muscle aged for one or seven days, coupled with more tender meat than NB. Pairwise correlations between growth and muscle characteristics indicated that fast growing animals tend to produce less tender meat. South African Journal of Animal Science, Vol 31, Issue 3, Oct – Dec (2001): pp.181-19

Effects of short and extended fasting periods and cattle breed on glycogenolysis, sarcomere shortening and Warner-Bratzler shear force

The effects of short (three hours) and extended (24 hours) feed withdrawal periods and three cattle breeds on muscle energy metabolism, sarcomere length, and meat quality were investigated. Brahman (Br), Nguni (Ng), and Simmental (Sm) bulls were subjected to ante-mortem feed withdrawal of three hours (Br3, n = 10; Ng3, n = 10; and Sm3, n = 10) or 24 hours (Br24, n = 10; Ng24, n = 10; and Sm24, n = 10). M. longissimus was used as the reference muscle for sampling. pH, and temperature was recorded at 1, 2, 3, 6, 9, and 24 hours post mortem. Samples for energy metabolites were removed at 3, 6, 9 and 24 hours post mortem. Glycogen, glucose-6-phosphate and creatine phosphate concentration were determined at each time interval as glycosyl units after hydrolysis. Samples to determine sarcomere length were removed at one and three days post mortem. Homogenates of the samples were placed under a 31,000 magnification microscope and sarcomere lengths were measured. Warner-Bratzler shear force (WBSF) was measured with an Instron meter at 1, 7 and 14 days post mortem. Glycogen was lower for Br24 and Ng24. There were no differences in glucose-6-phosphate, rate of creatine phosphate decline, average sarcomere length, or WBSF for Br24 and Ng24 compared with Br3 and Ng3. There were no differences for WBSF between Br3, Ng3 and Sm3. Glycogen concentration was higher for Sm24 compared with Sm3; glucose-6-phosphate was lower for Sm24 compared with Sm3; and the rate of creatine phosphate decline was higher for Sm24 compared with Sm3. Average sarcomere length was shorter and WBSF was higher for Sm24 compared with Sm3. The effect of prolonged ante-mortem feed withdrawal on tenderness is breed specific. Warner-Bratzler shear force was affected significantly by an extended feed withdrawal period in Simmental cattle only.The Red Meat Research and Development Trusthttp://www.sasas.co.za/journalsam2018Animal and Wildlife Science

Effect of South African beef production systems on post-mortem muscle energy status and meat quality

Post-slaughter muscle energy metabolism and meat colour of South African production systems were compared; steers (n=182) of Nguni, Simmental and Brahman crossbreds were reared on pasture until A-, AB-, or B-age, and in feedlot until A- and AB-age. After exsanguination carcasses were electrically stimulated (400 V for 15s); m. longissimus dorsi muscle energy samples were taken at 1, 2, 4 and 20 h post-mortem and samples for meat quality studies were taken at 1, 7 and 14 days post-mortem. Production systems affected muscle glycogen, glucose, glucose-6-P, lactic acid, ATP, creatine-P and glycolytic potential (P<0.05), with the muscles of feedlot carcasses having faster glycolysis rate than pasture carcasses. Energy metabolites correlated (0.4<r<0.9) with meat colour (CIE, L*a*b*), and (0.30.5) water holding capacity, drip loss, and Warner Bratzler shear force. Muscle energy only affected muscle contraction of the A-age-pasture system (shortest sarcomere length of 1.66 μm vs 1.75 μm and highest WBS of 6 kg vs 5 kg; 7 days post-mortem).The Agricultural Research Council (ARC) is acknowledged for their facilities and THRIP and the RMRDT for financial support.www. elsevier.com/locate/meatscihb201

Effect of dietary beta-agonist treatment, vitamin D-3 supplementation and electrical stimulation of carcasses on colour and drip loss of steaks from feedlot steers

In this study, 20 young steers received no beta-agonist (C) and 100 animals all received zilpaterol hydrochloride (Z), with 1 group receiving Z while the other 4 groups receiving Z and vitamin D3 at the following levels (IU/animal/day) and durations before slaughter: 7 million for 3 days (3D7M) or 6 days (6D7M), 7 million for 6 days with 7 days no supplementation (6D7M7N) and 1 million for 9 days (9D1M). Left carcass sides were electrically stimulated (ES) and right sides not (NES). Samples were analysed fresh or vacuum-aged for 14 days post mortem. Parameters included drip loss and instrumental colour measurements. In general, zilpaterol showed increased drip loss, lighter meat, and reduced redness. Vitamin D3 supplementation could not consistently overcome these negative effects. All vitamin D3 treatments reduced drip loss of stimulated aged steaks.THRIP and the RMRDT.http://www.elsevier.com/locate/meatscinf201

Effects of a beta-agonist treatment, Vitamin D3 supplementation and electrical stimulation on meat quality of feedlot steers

In this study, 20 young steers received no beta-agonist (C), 100 animals all received zilpaterol hydrocholoride (Z), with 1 group only receiving Z while the other 4 groups received zilpaterol and vitamin D3 at the following levels (IU/animal/day) and durations before slaughter: 7 million for 3 days (3D7M); 7 million for 6 days (6D7M); 7 million for 6 days with 7 days nor supplementation (6D7M7N) and 1 million for 9 days (9D1M). Left carcass sides were electrically stimulated (ES) and the right side not stimulated (NES). Samples were aged for 3 or 14 days post mortem. Parameters included Warner –Bratzler shear force (WBSF), myofibril filament length, sarcomere length and calpastatin and calpain enzyme activity. Both ES and prolonged aging reduced WBSF (P<0.001). 6D7M, 6D7M7N and Z remained significantly tougher than C (P<0.001), while 3D7M and 9D1M improved WBSF under NES conditions. ES is more effective to alleviate beta-agonist induced toughness than high vitamin D3 supplements.THRIP and the RMRDT.http://www.elsevier.com/locate/meatscinf201

The beef tenderness model

In Phase1 of this study, three breed types (Simmentaler-, Brahman- and Nguni bulls; n = 60 each) were grain-fed and slaughtered at 12 months of age (A-age, fat-class 2). Feed was withdrawn for either three hours or 24 hours pre-slaughter. Within each feed withdrawal group, three electrical stimulation (ES) treatments were applied, viz. ES for 15 seconds, 120 seconds or no stimulation. In Phase 2, the effects of animal age and feeding regime were investigated using of A-age (feedlot and pasture), AB-age (feedlot and pasture) and B-age (pasture) animals. All carcasses were electrically stimulated for 15 seconds. Longer feed withdrawal increased dark-firm-dry (DFD) meat occurrence (pHu >6) in the Nguni and Simmentaler-cross. Brahman-cross longissimus (LL) tended to be more tender with paler colour and higher drip loss when 120 ES was applied. Longer feed withdrawal recorded higher Warner Bratzler shear force (WBSF) than three hour feed withdrawal. However, ES neutralized the effect of stress on tenderness. On average the AB-age feedlot animals produced the most tender LL followed by the B-age pasture and A-age feedlot which was similar to the AB-age pasture. A-age pasture animals produced the least tender LL steaks. The calpain proteolytic system played a pivotal role in determining the ultimate meat tenderness and although connective tissue becomes less soluble in older animals it did not play the determinant role in tenderness in this study. The intramuscular fat (< 3%) played an important role in the tenderness outcome of Nguni LL which marbled well at AB-age.We acknowledge Agricultural Research Council, Red Meat Research and Development South Africa, and Meat Industry Trust for facilities and financial support. This work is also based on the research supported in part by the National Research Foundation of South Africa (UID 75120).http://www.sasas.co.za/am201

Urinary catecholamine concentrations in three beef breeds at slaughter

Animal welfare has become an important determinant of meat quality with poor animal temperament leading to huge economic losses to the meat industry due to carcass bruising and condemnation. Handling and transport of live animals is a stressful experience for animals. The temperaments of cattle affect their behaviour and differ between breeds, i.e. studies have shown that Bos indicus types are more temperamental than Sanga and Bos taurus types. Catecholamines (CAT’s) are considered as indicators of stress, because higher concentrations of CAT’s in brain tissue were noted in animals that are better adapted to stressful situations. In the present study, urinary CAT’s of three beef breeds were determined immediately post mortem. Brahman cattle represented Bos indicus types, Simmentaler cattle represented Bos taurus types and Nguni cattle represented the Sanga type. Nguni steers showed higher urinary norepinephrine (NE) and epinephrine (E) concentrations than Brahman and Simmentaler steers. Simmentaler steers showed a higher concentration of urinary dopamine (DA) than Br and Ng. The results suggest that Nguni cattle are less stress sensitive compared to the other beef breeds studied. These observations may be due to the process of domestication and selection for specific genes that influence tameability and consequently resulting in a shift in circulating concentrations of urinary CAT’s.Peer-reviewed paper: Proc. 44th Congress of the South African Society for Animal Sciencehttp://www.sasas.co.zaam201