Intake, digestion and gastro-intestinal mean retention time in Asiatic buffaloes and Ayrshire cattle given two contrasting diets and housed at 20° and 33 °C

Abstract

SUMMARY Four adult (4·5–7 years old) swamp buffaloes ( Bubalus bubalis )and four adult (4–5 years old) Ayrshire cattle ( Bos taurus ) were housed in climate chambers maintained at 20° or 33 °C and given ad libitum access to a medium-quality, complete pelleted diet (AA6) or a lower-quality pelleted diet of alkali-treated barley straw supplemented with urea, sulphur, minerals and vitamins (ATS). Using a balanced double cross-over design, each animal was studied at each temperature and whilst consuming each of the two diets in experimental periods lasting 20 days. On day 13 of each period, animals were given single doses of two nonabsorbable markers, and food intake and complete collections of faeces were measured for the remainder of the period. Blood samples were taken at the end of each period. Voluntary food intakes on a per kg body weight (W) or per kg W 0·75 basis were significantly higher for the cattle than for the buffaloes, although this difference was reduced with the lower-quality diet and at the higher temperature. Cattle appeared to be more heat stressed at 33 °C than the buffaloes, but species had little effect on digestion or gastro-intestinal mean retention time. Calculations suggested that a greater proportion of digestion of ATS than of AA6 occurred postruminally.