Prediction of metabolisable energy concentrations of fresh-cut grass using digestibility data measured with non-pregnant non-lactating cows.
Pasture-based ruminant production systems are common in certain areas of the world, but energy evaluation in grazing cattle is performed with equations developed, in their majority, with sheep or cattle fed total mixed rations. The aim of the current study was to develop predictions of metabolisable energy (ME) concentrations in fresh-cut grass offered to non-pregnant non-lactating cows at maintenance energy level, which may be more suitable for grazing cattle. Data were collected from three digestibility trials performed over consecutive grazing seasons. In order to cover a range of commercial conditions and data availability in pasture-based systems, thirty-eight equations for the prediction of energy concentrations and ratios were developed. An internal validation was performed for all equations and also for existing predictions of grass ME. Prediction error for ME using nutrient digestibility was lowest when gross energy (GE) or organic matter digestibilities were used as sole predictors, while the addition of grass nutrient contents reduced the difference between predicted and actual values, and explained more variation. Addition of N, GE and diethyl ether extract (EE) contents improved accuracy when digestible organic matter in DM was the primary predictor. When digestible energy was the primary explanatory variable, prediction error was relatively low, but addition of water-soluble carbohydrates, EE and acid-detergent fibre contents of grass decreased prediction error. Equations developed in the current study showed lower prediction errors when compared with those of existing equations, and may thus allow for an improved prediction of ME in practice, which is critical for the sustainability of pasture-based systems.
['Stergiadis|Sokratis|S|', 'Allen|Michelle|M|', 'Chen|Xianjiang|X|', 'Wills|David|D|', 'Yan|Tianhai|T|']
D000465:Algorithms D000821:Animal Feed D000818:Animals D002417:Cattle D016208:Databases, Factual D004063:Digestion D002149:Energy Intake D004734:Energy Metabolism D005260:Female D008697:Methane D008954:Models, Biological D009660:Northern Ireland D009753:Nutritive Value D035261:Plant Components, Aerial D006109:Poaceae D062211:Spatio-Temporal Analysis D013223:Statistics as Topic
Prediction Metabolisable energy Grass Digestibility Pasture-based ruminant production Grazing: Maintenance feeding