N-alkanes to estimate voluntary forage intake of cattle using controlled-release capsules

Abstract

N-alkanes have been used as internal markers in digestibility trials with ruminants and non-ruminants for more than 20 years. In this study, two trials were conducted under different feeding regimes to (i) evaluate the release rate of n-alkanes of controlled-release capsules in the rumen of rumen-cannulated steers either grazing or restrained in metabolic stalls and (ii) estimate voluntary forage intake of the same steers in metabolic stalls. Six rumen-cannulated Nelore steers were allocated to individual metabolic stalls and were fed diets with varying forage to concentrate ratios (80:20, 60:40, and 40:60; respectively). Corn silage was the only forage source. In the grazing trial, the same steers were evaluated under three feeding managements (Brachiaria brizantha cv. Marandu unsupplemented or supplemented with either 0.3% or 0.6% of live weight of a concentrate). The release rate of the nalkanes (mg d ).There was an effect of day of measurement (P < 0.05) on the release rate of animals restrained in metabolic stalls and grazing. However, no effect (P > 0.05) of feeding management or feeding management × day of measurement interaction was observed. Values averaged 6.9 and 14.8%, lower than proposed by the manufacturer for the C 32 , when animals were restrained in metabolic stalls and at grazing, respectively. Similarly, the values of C 36 were 15.9 and 23.1% lower for those animals in metabolic stalls and grazing, respectively. The average release rate of C 32 into the rumen was 372 and 341 mg d -1 for animals restrained in metabolic stalls and grazing, respectively. There was no difference in the release rate between feeding regimes (P > 0.05). The regression of the pooled data indicated an average release rate of 345 mg d -1. Estimated values of voluntary forage intake using the pair of C 33 :C 32 n-alkanes using the animals restrained in metabolic stalls was not different from those effectively measured (P > 0.05). These findings indicated that n-alkanes capsules can be used to estimate forage intake of stall-fed animals, but concentration of n-alkanes in capsules and the release rate has to be measured before dosing animals to accurately predict intake. Key words: bovine, fecal recovery, hydrocarbons, markers, dry matter intake N-ALCANOS PARA ESTIMAR O CONSUMO VOLUNTÁRIO DE FORRAGEM EM BOVINOS USANDO CÁPSULAS DE LIBERAÇÃO CONTROLADARESUMO: N-alcanos têm sido usados como marcadores internos em ensaios de digestibilidade com ruminantes e não-ruminantes por mais de 20 anos. Neste estudo dois ensaios foram conduzidos para avaliar: 1) a taxa de liberação de alcanos de cápsulas de liberação controlada inseridas no rúmen de novilhos fistulados em pastejo ou mantidos em gaiolas de metabolismo e; 2) o uso de n-alcanos para estimar o consumo voluntário de forragem dos novilhos mantidos em gaiolas de metabolismo. Seis novilhos Nelore, fistulados no rúmen foram colocados individualmente em gaiolas de metabolismo e alimentados com dietas variando a relação forragem:concentrado ( ). Houve um efeito de dia (P...

Combination of long-chain alcohols and fatty acids with alkanes as faecal markers to estimate feed intake and digestibility in horses and cattle fed on grass-heathland vegetation communities

“…Alkane markers have been proposed as a valuable technique to estimate feed intake of cattle (Oliveira et al 2008;Undi et al 2008;Morais et al 2011) and horses Smith et al 2007). Mayes et al (1986) suggested that feed intake could be determined using a dosed even-chain alkane marker (to measure faecal output) together with a dietary odd-chain alkane (to measure digestibility).…”

Long‐chain alcohols did not improve predictions of the composition of tall fescue and red clover mixtures over n‐alkanes alone

“…Determining feed intake and diet composition is therefore important. The use of plant waxes as markers in forage and faeces has been shown to reliably predict both (Dove and Charmley, ; Oliveira et al ., ; Pérez‐Ramirez et al ., ).…”

Comparing plastic syringes and disposable columns to extract n-alkanes in forage and concentrate feeds

“…Loss of solvent before fitting samples in the syringes was avoided by using cut disposable needles with tips sealed with epoxy resin. After rinsing the nalkanes fraction, identification and quantification of nalkanes was made using the C 34 as an internal standard through chromatographic analysis following procedure described by OLIVEIRA et al (2008).…”