Detalhes bibliográficos
| Ano de defesa: |
2014 |
| Autor(a) principal: |
Silva, Sílvia Rodrigues Carneiro
 |
| Orientador(a): |
Magnabosco, Cláudio Ulhôa
|
| Banca de defesa: |
Eifert, Eduardo da Costa,
Costa, Marcos Fernando Oliveira e,
Prado, Cristiano Sales |
| Tipo de documento: |
Dissertação
|
| Tipo de acesso: |
Acesso aberto |
| Idioma: |
por |
| Instituição de defesa: |
Universidade Federal de Goiás
|
| Programa de Pós-Graduação: |
Programa de Pós-graduação em Ciência Animal (EVZ)
|
| Departamento: |
Escola de Veterinária e Zootecnia - EVZ (RG)
|
| País: |
Brasil
|
| Palavras-chave em Português: |
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| Palavras-chave em Inglês: |
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| Área do conhecimento CNPq: |
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| Link de acesso: |
http://repositorio.bc.ufg.br/tede/handle/tede/5084
|
Resumo: |
The finishing cattle in feedlots has increased in recent years and the feeding of animals is responsible for 60-70% of the costs in this system. Cattle tend to select their food, even when this is provided in the form of a total mixed ration. This selective behavior has shown changes in milk production, but has been little studied in cattle. Thus, this study was designed to identify selection by particle size by cattle and a possible influence on performance and carcass beef cattle. We used 18 Nellore bulls, with 21 months old and average weight of 334 kg, confined for 127 days to reach slaughter weight of 500 kg and minimum subcutaneous fat thickness of 4 mm. The diet was corn silage and concentrate in the ratio of 40:60 dry matter basis. The diet was weighed and made up the evaluation of particle size by the method of sieves of the Penn State Particle Size Separator, every four hours for 24 hours. From these results, the animals were grouped according to the habit of selection by particle size using cluster analysis into two stages: the Ward method to define the number of cluster; and kmeans clustering method to classify animals into groups by Euclidean distance, where k = 3, these being the three groups evaluated: Group 3 showed a preference for long (> 19 mm) and medium particles (<19 mm> 8 mm), Group 1 showed no preference for distinction as the size of particles throughout the day, but the proportion of fine particles (<1.18 mm - bottom of sieve) decreased after 24h and Group 2 presented similarity throughout the day, with the Group 1 or Group 3. There was no significant effect between groups for any carcass traits (carcass yield, percentage industrial cuts, Loin Area, fat thickness and percentage of fat in carcass). On feedlot performance, there were no differences in time spent on food, idling or rumination, as well as the dry matter and NDF intake. However, weight gain and attributes of efficiency (conversion and feed efficiency) showed significant effects at P <0.07 between groups with statistical difference of P <0.007 for feed efficiency and P <0.0109 for feed conversion between Groups 1 and 3 when compared alone. It was concluded that selection by particle sizes does not imply changes in the performance of feedlot cattle diets with 40% forage and fed twice a day. |
