A survey of the literature showed that forage processing, that is grinding and pelleting, increased feed intake of ruminants. This increase, due to reduction in particle size distribution of the forage, depends mainly on forage quality, proportion of concentrates in the diet and nutrient requirement of the cow. Pellets could replace part of the concentrates; complete substitution for long forage caused digestive disorders and reduced fat content of the milk. Eating rate, microbial breakdown and production of volatile fatty acids often increased too. Processed forages offered to sheep and beef cattle depressed digestibility, which was compensated by slightly lower losses of methane and less heat production.Data from energy balance trials at Wageningen from 1967 to 1973, mostly with 4-6 lactating Dutch Friesian cows per trial, were examined by multiple factor analysis for effects of processing. Rations in which processed forages replaced part of the long forages or the concentrates were tested in 130 trials. Processing decreased digestibility of energy in the forage by about 9 percentage units, 15%, and its metabolizability by 7 percentage units, 13%. Utilization of metabolizable energy increased, roughly compensating the decrease in metabolizability. Regressions were calculated for the prediction of digestibility and net energy of processed forage in a feed evaluation system for dairy cows, to be introduced in the Netherlands in 1977.
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