Blood cell and metabolic profile of Nellore bulls and their correlations with residual feed intake and feed conversion ratio

Perfis sanguíneo e metabólico de touros Nelore e suas correlações com consumo alimentar residual e taxa de conversão alimentar

Abstracts

Due to the potential metabolic changes related to the residual feed intake (RFI), this study investigated the correlation of traditional RFI (RFI1), RFI adjusted for final rump fat thickness (RFI2) and feed conversion ratio (FCR) with the metabolic and blood profiles, as well as determined the possible different classes of RFI1 and RFI2. For this purpose, 46 Nellore bulls, 22 month-old and 411kg of weight at the beginning of the study were used. The animals were fed with the same diet for 84 days, and blood samples were collected every 21 days for evaluation of serum metabolites and blood cell profiles. No significant correlations were found between FCR and metabolic or blood traits, although there was a significant correlation between RFI1 and urea serum concentration. There were also differences between the RFI classes for creatinine, in which more efficient animals showed higher values. The RFI2 did not correlate with any metabolic and blood cell variable, but young bulls with smaller RFI2 had a smaller number of eosinophils when compared to animals with higher RFI2. These results suggest that animals with a high RFI can have greater energy expenditure due to protein synthesis and degradation process, resulting in a larger blood urea level.

beef cattle; feed efficiency; metabolism

Em função das diversas variações metabólicas relacionadas com o consumo alimentar residual (CAR), objetivou-se nesse estudo avaliar as correlações do CAR tradicional (CAR1), CAR ajustado para deposição de gordura subcutânea na garupa (CAR2) e da conversão alimentar (CA) com o perfil metabólico e sanguíneo, assim como verificar as possíveis diferenças das classes de CAR1 e CAR2. Para tanto, foram utilizados 46 touros da raça Nelore com 22 meses de idade e 411kg no início do estudo. Os animais foram alimentados com a mesma dieta durante 84 dias, nesse período foram coletadas a cada 21 dias amostras de sangue para avaliação de metabólitos no soro e do perfil celular no sangue. Não foram encontradas correlações significativas da CA com nenhuma característica metabólica ou sanguínea, já para o CAR1 foi encontrada correlação significativa para a concentração de ureia sérica, também houve diferença entre as classes com relação à creatinina, na qual animais mais eficientes apresentaram valores superiores para essa variável. O CAR2 não foi correlacionado com nenhuma variável metabólica e das células do sangue, porém animais de menor CAR2 tiveram menor quantidade de eosinófilos quando comparados com os animais de maior CAR2. Esses resultados sugerem que animais menos eficientes para CAR podem ter maior gasto energético com processos de síntese e degradação proteica corporal, devido à maior quantidade de ureia presente no sangue.

bovinos de corte; eficiência alimentar; hemograma; metabolismo

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Publication Dates

• Publication in this collection
  22 Nov 2013
• Date of issue
  Sept 2013

History

• Received
  21 Mar 2013
• Accepted
  13 Sept 2013