Digestibility and protein utilisation of silages of grass, red clover-grass and maize by rams

摘要

The aim was to evaluate differences in in vivo digestibility and protein utilisation of silages fed to rams. Grass silage (G) from first cut, red clover-grass silage (RC 75% + G 25%) from third cut without inoculant (RC-G) and with bacterial inoculant(RC-G+I; L. plantarum, L. buchneri, 2 x 105 cfu g1) and maize silage harvested at dough stage (EM) and at dent stage (LM) of maturity were fed to 10 rams in a duplicated 5x5 Latin square, where half of the rams (1 square) received 150 g of rapeseed mealdaily. G had higher organic matter digestibility than RC-G and LM (76, 65 and 69%, respectively). Neutral detergent fibre digestibility was highest for G (7)<0.001). Nitrogen intake and excretion of urea in urine were greatest for RC-G followed by G andmaize. Excretion of purine derivatives in urine was greater for G than for RC-G and EM (4.8 vs 3.4 g d"1; P<0.001), which did not differ. No effects of inoculant in RC-G and of maturity stage in maize were found. Thus, G silage can be used as a sole forage whereas RC-G and maize silages need to be combined to optimize energy and protein utilisation by ruminants.