Rapeseed and linseed oil supplementation affects hydrolytic activities in the rumen of sheep

ABSTRACT The aim of this study was to compare the effect of two sources of dietary oils: rapeseed oil (abundant source of oleic acid) and linseed oil (abundant source of linolenic acid) on the activity of polysaccharidases in sheep rumen. The experiment was carried out on six rumen-fistulated sheep. The animals were divided into three sup-groups of two sheep. Each sup-groups received different sequence of three treatments (control, rapeseed or linseed oils), which resulted in three periods of study. Sheep were fed a diet consisting of meadow hay and moderate amount of concentrates content without or with the addition of rapeseed or linseed oils (50 g/day). The dose of added oils allowed to increase fat content in dietary dry matter from 2 to 7%. After the adaptation period (21 days), rumen digesta was collected for 2 consecutive days before and 2, 4 and 8 hours after morning feeding to analyze enzymatic activity. Celulolytic activity decreased 2 and 4 h after feeding when sheep were fed diets with rapeseed or linseed oils in comparison to the control diet. Before feeding, pectinolytic activity was lower in sheep fed oils than in control, but this activity 8 hours after feeding was the lowest in animals receiving rapeseed oil. Neither of oil supplements influenced xynalolytic, inulinolytic and amylolytic activity in the rumen of sheep. Irrespective of treatment, xylanolytic activity was the lowest 2 and 4 h after feeding, and the highest at sampling at 0 h. No treatment × time interaction for inulinolytic activity was shown. Comparing sampling time points regardless examined treatment, the amylolytic activity was significantly higher after 2 h after feeding than 0 and 4 h after feeding. Our data suggested that rapeseed or linseed oil administration to sheep rations modified polysaccharidase activities in the rumen. Both oils, rapeseed and linseed, decreased celulolytic activity in sheep rumen. The addition of rapeseed oil to the diets resulted in decreased pectinolytic activity in the rumen.