Abstract
This experiment was carried out to evaluate performance and carcass characteristics of 40 crossbred young bulls (ZebuxEuropean) finished in a feedlot under two roughage sources (Bermuda grass hay or sorghum silage) with or without the addition of yeast (Saccharomyces cerevisae). The bulls were 20 months old, their initial average weight was 356 kg and they were allocated into four groups of ten animals. The experimental diets were Bermuda grass, Bermuda grass+yeast, sorghum silage and sorghum silage +yeast. Animal performance and carcass characteristics were not influenced by roughage source or yeast addition. The average daily weight gain was 1.50 kg, dry matter intake (DMI) was 11.1 kg/d, DMI as percentage of liveweight was 2.60% and feed dry matter conversion was 7.70. The mean dressing percentage was 52.0% and hot carcass weight was 268 kg. Carcass conformation was classified between good-minus to good. Carcass length (137 cm), leg length (72.9 cm) and cushion thickness (26.6 cm) were not influenced by treatments. The average fat thickness was 3.80 mm and the Longissimus muscle area was 66.9 cm 2 . The classification of color, texture and marbling were slightly dark red to red, fine and slight-minus to light-typical, respectively. The mean percentage of bone, muscle and fat in the carcass was 15.5%, 62.3% and 22.5%, respectively. Yeast addition increased γ-linolenic fatty acid (0.15 vs. 0.11%) deposition. Bermuda grass hay increased deposition of α-linolenic (0.49 vs. 0.41%), arachidonic (2.30 vs. 1.57%), eicosapentaenoic (0.41 vs. 0.29%), docosapentaenoic (0.80 vs. 0.62%), docosahexaenoic (0.11 vs. 0.06%) and n-3 fatty acids, and reduced n-6: n-3 ratio in meat, when compared to sorghum silage treatments. The treatments had no effect on saturated fatty acids (49.5%), polyunsaturated fatty acids (11.8%), n-6 fatty acids (9.87%), n-3 (1.61%) and PUFA:SFA ratio (0.24). Monounsaturated fatty acid levels were higher on sorghum silage (40.7 vs. 37.7%). The addition of yeast caused higher n-6: n-3 ratio (7.28 vs. 5.70) than treatments without yeast.
Highlights
Brazil has the largest commercial cattle herd in the world, with approximately 159 million animals and a production of approximately 8.2 million tons of carcass each year (Anualpec, 2007)
Brazil’s prospects of consolidating its position in the world beef market have required that the beef industry constantly raise its standards to supply ever higher quality products (Prado, 2004). Meeting this goal is made more difficult by the stagnation in silage production, because 90% of beef produced in Brazil comes from animals raised in pasture systems (Prado and Moreira, 2002)
Texture (TXT) : This was determined through the size of the fascicle and evaluated subjectively with a point scale, to that of marbling
Summary
Brazil has the largest commercial cattle herd in the world, with approximately 159 million animals and a production of approximately 8.2 million tons of carcass each year (Anualpec, 2007). Brazil’s prospects of consolidating its position in the world beef market have required that the beef industry constantly raise its standards to supply ever higher quality products (Prado, 2004). Meeting this goal is made more difficult by the stagnation in silage production, because 90% of beef produced in Brazil comes from animals raised in pasture systems (Prado and Moreira, 2002). Researchers have concentrated since the 1980s on crossbreeding between Zebu and European breeds, with the objective of increasing production and quality in the meat of offspring (Perotto et al, 1998; Perotto et al, 2000).
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