Publicação: The validity of n-alkanes to estimate intake and digestibility in Nellore beef cattle fed a tropical grass (Brachiaria brizantha cv. Marandu)
Carregando...
Data
Orientador
Coorientador
Pós-graduação
Curso de graduação
Título da Revista
ISSN da Revista
Título de Volume
Editor
Elsevier B.V.
Tipo
Artigo
Direito de acesso
Acesso restrito
Resumo
The objective of the present experiment was to evaluate the ability of n-alkanes to estimate dry matter (DM) intake (DMI) and digestibility (DMD) in Nellore beef cattle fed a tropical grass cut at two growth stages (30 or 60 days). The effect of two different faecal sampling procedures (daily pool-Total- or rectal spot-Spot-samples) was also tested. Differences in faecal concentration between sampling methods were lower than 2% and 0.7% for 30-d and 60-d old grass, respectively, with slightly higher values in Spot samples. Faecal recoveries were not affected by the grass growth stage, except in the cases of C(31), C(33), and C(35) (P < 0.05), which were lower for 30-d compared to 60-d. There was lower ratio (P < 0.05) between internal and external recovery alkane pairs C(31)/C(32), C(33)/C(32) and C(35)/C(36) in treating 30-d treatment than in 60-d old grass. Faecal recovery of natural alkanes increased with chain length, recoveries up to 77.0% (C(35)), whereas dosed alkanes C(28), C(32) and C(36) showed average recoveries of 94.2%, 97.2% and 86.8%, respectively. Estimates of DMI were different from current values (P < 0.05) when used C(31)/C(32). C(33)/C(32) and C(35)/C(36) natural/dosed alkane pairs, regardless of the sampling procedure. An exception was the DMI estimated using the C(35)/C(36) alkane pair of the samples of total sampling, which does not differ from the actual values (P > 0.05). However, using recovery-corrected faecal concentrations reduced the differences between observed and estimated values (P > 0.05). Similarly, the DMD was underestimated with the alkanes C(31). C(33) and C(36), regardless of the method of sampling. Observed effect of forage development stage in the estimates of DMD (P < 0.05), (lower values for 30-d treatment were observed than in the 60-d), due to lower faecal recovery of alkanes in the 30-d treatment. By correcting the concentrations of alkanes with the faecal recovery of the individual alkane, the differences between the estimated and actual values were canceled (P > 0.05), regardless of age of forage, the alkane used or the sampling method. (c) 2010 Elsevier B.V. All rights reserved.
Descrição
Palavras-chave
n-alkanes, Beef cattle, Markers, Palisade grass, Stage growth
Idioma
Inglês
Como citar
Livestock Science. Amsterdam: Elsevier B.V., v. 135, n. 2-3, p. 184-192, 2011.
