Intake, digestion, gastro-intestinal transit time and nitrogen balance in working oxen: studies in Costa Rica and Nepal

Abstract

AbstractExperiments were carried out in Nepal and Costa Rica to compare voluntary dry-matter intake (DMI) by oxen of diets based on poor quality hay (Costa Rica) and rice straw (Nepal) supplemented with different levels of concentrate foods when the animals were working and not working. Values for the apparent digestibility of the diets, rates of passage of solid and liquid phases ofdigesta and nitrogen balance are also reported.Amounts of work calculated to raise daily energy expenditure to 1·3 to 1·6 × maintenance were associated with the following effects. (1) A depression of proportionately 0·11 and 0·14 in the DMI of oxen given a diet based on rice straw plus 18 and 27 g/kg live weight of concentrate respectively during work. No depression of DMI was seen with the hay diets which had slightly higher metabolizable energy but less nitrogen than the rice straw diets. (2) An increase in intake in the weeks following work on both the hay and rice straw diets. (3) Variable effects on apparent digestibility of food probably related more to the changes in DMI. (4) A tendency for gastro-intestinal mean retention time to be increased in working weeks particularly on the more fibrous diets.