Evaluation of rumen microbial nitrogen supply in Batur sheep fed different ratio of concentrate-forage diets

Abstract

Abstract Concentrate-forage ratio may affect microbial nitrogen supply, thus it can be considered as one of feeding strategies in ruminant. This study evaluated the effect of different concentrate-forage ratio on rumen microbial nitrogen supply in Batur sheep. Twelve male Batur sheep aged 10-12 months were given three experimental diets in a one-way design using 14 d adaptation and 7 d collection periods. Experimental diets were concentrate (wheat pollard) and forage (Pennisetum purpuroides) offered with ratio of 20:80, 30:70, and 40:60 (w/w, DM basis). Total urine were collected for 24 h during collection period. Samples were analysed for allantoin, uric acid, xanthine-hypoxanthine, and purine derivatives. Feed and feed refusal were analysed for dry matter and organic matter. Concentrate-forage ratio tended to influence allantoin, xanthine-hypoxanthine, and purine derivatives excretions, as well as absorbed purine and rumen microbial protein synthesis. Feeding concentrate up to 40% significantly increased N urinary excretion (P<0.05). It indicated that concentrate level at 30% could fulfil animal protein requirement. Feeding concentrate-forage ratio 30:70 or 40:60 increased purine absorbed and microbial protein synthesis 2-3 fold higher than the ratio of 20:80. It is concluded that Batur sheep was efficient in utilizing degradable dietary N with concentrate: forage ratio of 30:70.