Search

Simmental x Holstein-Friesian steers were offered four forage diets. These comprised grass silage (G);proportionately 0.67 grass silage, proportionately 0 .33 maize silage (GGM); 0.33 grass silage, 0.67 maize silage (MMG); maize silage (M) from 424 (s.d. = 11.5)kg to slaughter at a minimum weight of 560 kg. Forages were mixed and offered ad libitum. Steers were offered 2 kg of a concentrate daily, the concentrate being formulated such that all steers had similar crude protein intakes across dietary treatments. A sample of steers was slaughtered at the beginning of the experimental period to allow the calculation of the rate of gain of the carcass and its components. Carcass dissection of a sample of steers allowed the development of a prediction equation of carcass composition based on thoracic limb dissection of all carcasses. Forage dry matter intake and live-weight gain increased linearly as maize silage replaced grass silage in the forage mixture, resulting in improvements in food conversion ratio (all P = 0.001). Killing-out proportion increased with maize silage inclusion (P < 0.001)but fat and conformation scores did not differ significantly between diets. However, increasing maize inclusion in the diet resulted in a greater weight (P = 0.05) and proportion (P = 0.008)of fat in the carcass, and significant increases in internal fat deposition. The inclusion of maize led to a progressive increase in the daily gains of carcass (P < 0.001), and significant increases in the daily gains of both fat (P < 0.001) and lean tissue (P < 0.001). Fat colour was more yellow in cattle given diets G and GGM than diets MMG and M (P < 0.001)and colour intensity was lower on diet M than the other three diets (P < 0.001).There were no significant differences in any aspects of eating quality between diets. Therefore, maize silage has the potential to reduce the time taken for finishing beef animals to achieve slaughter weight with no apparent detrimental effects on subsequent meat quality. [ABSTRACT FROM AUTHOR]

Meat quality describes the attractiveness of meat to consumers. The present paper focuses on two major aspects of meat quality, tenderness and flavour. Both aspects of quality can be influenced by nutrition, principally through its effects on the amount and type of fat in meat. In several countries, high levels of intramuscular fat (marbling fat), i.e. above 30 g/kg muscle weight in longissimus, are deemed necessary for optimum tenderness, although poor relationships between fat content and tenderness have generally been found in European studies, where fat levels are often very low, e.g. below 10 g/kg in UK pigs. Muscle lipid may be a marker for red oxidative (type 1) muscle fibres which are found at higher concentrations in tender muscles and carcasses. Nutritional treatment can be used to manipulate the fatty acid content of muscle to improve nutritional balance, i.e. increase the polyunsaturated (PUFA): saturated fatty acid value and reduce the n-6:n-3 PUFA value. Increasing PUFA levels may also change flavour because of their greater susceptibility to oxidative breakdown and the generation of abnormal volatile compounds during cooking. This situation particularly applies to the n-3 PUFA which are the most unsaturated meat lipids. In pigs, a concentration of 3 mg alpha-linolenic acid (18:3)/100 mg in muscle and fat tissue fatty acids can easily be achieved by including whole linseed in the diet. This level has led to abnormal odours and flavours in some studies, but not in others. In cattle and sheep, feeding whole linseed raised 18:3 concentrations in muscle fatty acids from about 0.7 mg/100 mg to > 1 mg/100 mg. As with pigs, this diet also increased levels of long-chain n-3 PUFA formed from 18:3, including eicosapentaenoic acid (20:5). Although this increase led to greater oxidative breakdown of lipids during storage and the generation of large quantities of lipid-derived volatile compounds during cooking, there were no deleterious effects on odour or flavour. When 18:3 levels are raised in lamb and beef because of grass feeding, the intensity of the flavours increases in comparison with grain-fed animals which consume and deposit relatively more linoleic acid (18:2). In ruminants, very high levels of 18:2 produced by feeding protected oil supplements cause the cooked beef to be described as oily, bland or pork-like. [ABSTRACT FROM AUTHOR]

Meat quality describes the attractiveness of meat to consumers. The present paper focuses on two major aspects of meat quality, tenderness and flavour. Both aspects of quality can be influenced by nutrition, principally through its effects on the amount and type of fat in meat. In several countries, high levels of intramuscular fat (marbling fat), i.e. above 30 g/kg muscle weight in longissimus, are deemed necessary for optimum tenderness, although poor relationships between fat content and tenderness have generally been found in European studies, where fat levels are often very low, e.g. below 10 g/kg in UK pigs. Muscle lipid may be a marker for red oxidative (type 1) muscle fibres which are found at higher concentrations in tender muscles and carcasses. Nutritional treatment can be used to manipulate the fatty acid content of muscle to improve nutritional balance, i.e. increase the polyunsaturated (PUFA) : saturated fatty acid value and reduce the n−6 : n−3 PUFA value. Increasing PUFA levels may also change flavour because of their greater susceptibility to oxidative breakdown and the generation of abnormal volatile compounds during cooking. This situation particularly applies to the n−3 PUFA which are the most unsaturated meat lipids. In pigs, a concentration of 3 mg α-linolenic acid (18 : 3)/100 mg in muscle and fat tissue fatty acids can easily be achieved by including whole linseed in the diet. This level has led to abnormal odours and flavours in some studies, but not in others. In cattle and sheep, feeding whole linseed raised 18 : 3 concentrations in muscle fatty acids from about 0.7 mg/100 mg to > 1 mg/100 mg. As with pigs, this diet also increased levels of long-chain n−3 PUFA formed from 18 : 3, including eicosapentaenoic acid (20 : 5). Although this increase led to greater oxidative breakdown of lipids during storage and the generation of large quantities of lipid-derived volatile compounds during cooking, there were no deleterious effects on odour or flavour. When 18 : 3 levels are raised in lamb and beef because of grass feeding, the intensity of the flavours increases in comparison with grain-fed animals which consume and deposit relatively more linoleic acid (18 : 2). In ruminants, very high levels of 18 : 2 produced by feeding protected oil supplements cause the cooked beef to be described as oily, bland or pork-like. [ABSTRACT FROM PUBLISHER]

This study investigated the effects of weaning and sex on various aspects of production and quality characteristics in 22 male and 18 female lambs of the Rasa Aragonesa local meat breed. Half the lambs were weaned (W) at 38 to 40 days and half were left unwearied (UW). Both groups were given ad libitum concentrates and cereal straw. Average farm weight was 22·1 kg at 78·3 days. Live-weight gain was significantly different between sexes but not between W and UW lambs. Dressing proportion was higher in UW lambs. Significant differences in fatness were found between W and UW lambs and between sex of lambs. Among the meat quality traits, W lambs had redder and UW lambs paler meat judged by colour a* and haem pigment concentration. No statistical differences were found in the other traits except flavour intensity, which was higher in UW (66·8) than in W (63·6) lambs on a 1 to 100 scale. All other eating quality aspects, in grilled m. longissimus lumborum slices, tended to be higher in UW lambs. The fatty acid composition of subcutaneous and intramuscular fat depots differed significantly (intramuscular fat was more unsaturated and polyunsaturated). There were also differences between W and UW lambs in subcutaneous fat (higher unsaturated in W lambs). However in intramuscular fat composition only differences in polyunsaturated fatty acids (higher in UW lambs), but not in total unsaturated or saturated, were observed. Tatty acids of less than C16 chain length were higher, in both fat depots, in UW lambs than in W lambs reflecting greater incorporation of milk fatty acids. Palatability characteristics were not closely associated with fatty acid composition except that flavour intensity was correlated with total saturated fatty acids. [ABSTRACT FROM PUBLISHER]