Fractional outflow of soybean meal from the rumen, water intake and ruminal fermentation pattern in sheep and goats at different seasons and age groups

Abstract

The effect of age (5 or 8 months old) on the fractional outflow rate (FOR) of chromium (Cr)-treated soya from the rumen of Chios lambs and Damascus kids (five animals per age group per species) was studied in Trial 1. The effect of season (spring, summer, winter) on the FOR of Cr-treated soybean meal (SBM) from the rumen, water consumption and ruminal fermentation pattern was determined in Trial 2 using four dry, mature, rumen fistulated Chios ewes and four Damascus goats per season. There was no difference in feed dry matter (DM) intake per kg 0.75 body weight (BW) between species in both trials. In Trial 1, neither animal species ( ) nor age ( ) affected FOR of Cr-treated SBM from the rumen. Moreover, there was no effect ( P > 0.1) of animal species and season on ruminal pH, NH 3-N and acetate molar proportion (Trial 2). Season affected propionate ( P < 0.007) and butyrate ( p < 0.005) molar proportions and water consumption. Water consumption was greater ( p < 0.001) in summer than in winter and spring, but not different between spring and winter. Ewes consumed more water ( p < 0.05) and had greater butyrate molar proportion ( p < 0.005) and total volatile fatty acid concentration ( P < 0.003) than goats. DM degradability of straw incubated in the rumen for 48 h was similar in ewes and goats, and was not affected by season. The FOR of Cr-treated SBM from the rumen was faster ( P < 0.022) in goats than in ewes. Season had only a small and non-significant ( P > 0.1) effect on FOR. Due to differences of results among trials, it does not seem advisable to propose, at least at present, different FOR for sheep and goats, and for different seasons of the year and/or between growing lambs and kids of varying age.