N. A. TODOROV1 and H. S. ALI2
1 Thracian University, Faculty of Agriculture, BG-6000 Stara Zagora, Bulgaria
2 Research Institute of Mountain Stockbreeding and Agriculture, BG-5600 Troyan, Bulgaria
TODOROV, N. A., and H. S. ALI, 2009. Effect of sunflower expeller supplementation on intake and digestibility of pasture grass with low protein content. Bulg. J. Agric. Sci., 15: 168-176
The aim of this study is to estimate the effect of protein level in supplement to summer-autumn natural pasture on grass intake and digestibility in dairy cows. In 2 x 2 Latin square trials with two groups, three animals each are tested two supplements to dairy cows grazing typical Bulgarian natural pasture with 5.6% legumes. The first supplement was 5 kg cow-1 day-1 sunflower expeller (SUN) with 264 g kg-1 crude protein (CP), and the second one 6 kg cow-1 day-1 compound feed (COM) with 156 g kg-1 CP. Intake and digestibility of pasture grass was estimated by double markers - acid insoluble ash and chromium sesquioxide. SUN and COM digestibility was determined in classical in vivo experiment with wethers. Equations were developed for calculation of intake and digestibility of pasture grass when animal received supplemental feeds. The cows supplemented with SUN intake approximately 450 g more organic matter with pasture grass, compare to cows receiving COM (P<0.05). The digestibility of pasture grass was 0.575 - 0.598 and 0.545 - 0.575 respectively for supplementation with SUN and COM (P<0.05). Difference in intake and digestibility is due mainly on higher level of CP in DM of diet with SUN equal to 187 g kg-1 vs. 140 g kg-1 diet with COM. Modified markers method for estimation of intake and digestibility of pasture grass when animals received supplements is useful in research with grazing animals.