Uso del polietilenglicol (PEG-6000) como indicador de la ingestión en ganado vacuno: puesta apunto del método en estabulación

Abstract

Polyethyleneglycol 6000 (PEG) was selected as a potential indigestible estimator of faecal output in cattle. NIRS-calibration equations of PEG faecal content were obtained with faeces from hay-fed cows with 0 to 10% PEG content. A digestibility trial was conducted with 8 dry cows in digestibility cages for two 3-wk periods, during which half the cows received either a Low (9 kg hay, as fed) or High (12 kg hay) feeding level (FL), and were dosed daily during the last 10 d either 175 (Low) or 235 (High FL) g PEG/d. In the last 4 d total faeces were collected, and in the last day rectal samples were obtained every 4 h. Samples were NIRS-scanned to determine faecal PEG content. Faecal PEG recovery was 95.7% in total faeces and 92.3% in rectal samples. Faecal output was slightly overestimated with PEG data from total faeces (+5.2%), and so was calculated feed intake, although only significantly in the High FL (+6.0%), while estimates were accurate in the Low FL. Data from rectal samples led to 27% overestimation irrespective of FL, therefore the practical interest of this technique should be reconsidered