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Abstract

Various forages commonly provided to dairy cattle were fed to cannulated steers in order to study dietary nitrogen breakdown and utilization. Feed intake and apparent digestibility of dry matter, fibre and nitrogen were monitored as well as microbial nitrogen production in the rumen. Two Holstein and two Ayrshire steers, each fitted with a re-entrant duodenal cannula were used. Two of the steers were also used before the cannulae were fitted. Five different forages were investigated: low quality grass hay (1.7%N), alfalfa cubes (2.3%N), high quality grass hay (2.7%N), Italian ryegrass (1.7%N) and orchard grass (2.1%N). For each forage, each steer was allowed a two-week adaptation period followed by a four-day digestiblity collection period. Fecal samples were obtained daily, and digesta samples were collected at the duodenum three times daily. Unfortunately, due to illnesses, only one steer was able to complete all of the digestibility trials with all of the forages. When low quality hay and alfalfa cubes were given, cannulation had no effect (p>.05) on feed intake or apparent digestibility of fibre and nitrogen. Only apparent digestiblity of dry matter was higher (p