Voluntary intake of several planted pastures by sheep and an assessment of NDF and IVDOM as possible predictors of intake.

Abstract

The aim was to study the quality and quantity of pasture selected by sheep on various planted pastures. A further aim was to assess NDF and IVDOM as easy measurable parameters for use in equations to predict intake. Pasture samples were collected using oesophageal-fistulated sheep and from knowledge of the in vitro digestibility of these samples and the total faeces voided as measured with faeces bags, intake was calculated. Pastures observed included ryegrass, cocksfoot, C. dactylon, Smuts finger, triticale, E. curvula, Eragrostis - lucerne combination, lucerne and sainfoin. Nitrogen content of oesophageal samples varied between 2, 3 and 5, 15 NDF between 33 and 65% and IVDOM between 50 and 80%. Intake of grass DOM varied from 24, 4 to 43, 3 g/kg W 0, 75/day for lambs and from 29, 0 to 37, 4 g/kg/W 0, 75/day for mature whethers. DOM intake on the two legumes was generally poor and varied between 13, 7 and 22, 9 g/kg W 0, 75/day. Although some of the variation in voluntary intake is accounted for by the variation in NDF and IVDOM, these two parameters are of limited value as general predictors, but may be used in selection indices.

Keywords: digestibility; digitaria eriantha; equation; grasses; in vitro digestibility; intake; ivdom; lambs; legumes; lucerne; neutral detergent fibre; nitrogen; oesophageal fistulas; oesophageal samples; pasture selection; pastures; ryegrass; sheep; smuts finger; south africa; university of pretoria