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| Author(s): |
Rodrigo Silva Goulart
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | Piracicaba. |
| Institution: | Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) |
| Defense date: | 2006-12-15 |
| Examining board members: |
Dante Pazzanese Duarte Lanna;
Mauricio Mello de Alencar;
Paulo Roberto Leme
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| Advisor: | Dante Pazzanese Duarte Lanna |
| Abstract | |
The interaction between environmental and genetic factors is extreme important in beef production systems. This study was conduced to evaluate the performance, efficiency and carcass quality of four biological types of beef cattle raised on pasture and finished in the feedlot. Forty seven steers were used and had 22 months of age and shrunk body weight of 310 kg. They were evaluated for performance, carcass characteristics and growth body composition. Steers were Nelore (NE), ½ Aberdeen Angus + ½ Nelore (AN), ½ Canchim + ½ Nelore (CN) e ½ Simmental + ½ Nelore (SN), all from the same cow herd. All genetic groups were analyzed and compared at the same age and same feedlot days. Diet had the following composition: 13.34% crude protein and 68.7 total digestible nutrients. Composition of the 9-10-11th rib cut was used to calculate empty body composition. Crossbreed cattle (AN e SN) had higher initial and final shrunk body weight, higher initial and final hot carcass weight, and higher initial and final empty body weight. Daily carcass, empty body and body gains were higher AN and SN cattle. AN steers had the highest dry matter intake, however there were no differences among the study groups for feed efficiency. AN had greater subcutaneous back fat (8.5mm) when compared to CN, NE and SN (4.4, 4.4 and 4.0 mm, respectively). AN steers had the smallest rib eye area (21.4 cm2/100 kg of carcass). Carcass dressing was greater for NE and CN. AN steers had lower muscle but greater fat content in the 9- 10-11th rib cut. AN and SN had the greater ether extract content and consistent with that lower water percentage in the empty body at slaughter. AN, NE and SN groups were similar in rate of energy deposition (6.06, 5.20 and 5.80 Mcal/day, respectively). The ether extract content of the empty body weight gain (EBWG) of AN steers (41.5%) was not different (P>0,05) from CN cattle (39.0%) and SN steers (38.6%). The SN crossbreds had greater protein requirements (0.164 kg/kg of EBWG) than AN and CN (0.140 and 0.142 kg/kg of EBWG, respectively). AN animals had the greatest net energy requirement for gain (4.685 Mcal/kg of EBWG). Data from this experiment can be used to estimate the nutritional requirements of Nelore and Nelore crossbreds from continental and british breeds. Body composition was influenced by biological type (breed or genetic group). Compared at the same age crossbreeding Nelore cows to Aberdeen Angus increased slaughter weight, body weight gain, fat deposition and energy requirements when compared to Nelore and Canchim x Nelore and Simmental x Nelore crossbreds. (AU) | |