PSI-28 Effect of supplementation with low-moisture, sugarcane molasses-based block on intake and ruminal volatile fatty acid profile on steers fed low quality forage

Abstract We evaluated the effects of supplementation of molasses based on low moisture molasses (LMB) on steers fed low quality forage in DM intake and ruminal VFA. Six rumen cannulated Nellore steers (23 months, 350 ± 10 kg) were distributed in a 3 × 3 double Latin square design. The treatments were composed of Brachiaria brizantha cv. Marandu ad libtum as an exclusive source of bulks (93.65% DM, 3.97% CP and 81.76% NDF) and supplements: complete mineral blend with urea [UR, (urea, salt, mineral-vitamin premix)], a commercial protein supplement [PS, (corn grain, soybean meal, urea, salt, and mineral- vitamin premix)] or protein block based on low-moisture cooked sugarcane molasses [LMB, (cane molasses, cottonseed meal, soybean oil, urea, salt and mineral-vitamin premix)]. Before subsequent feeding, samples of orts were collected to monitor the daily intake. After 14-d adaptation period, rumen fluid samples were collected in each experimental period at 0, 2, 4, 6, 8, 10, 12 and 14 h after feeding, to evaluate concentrations of VFA, which was determined by gas chromatography. The data were analyzed using Software R, with measures repeated in time for VFA and having as fixed effect the treatments and as animal random effect, period, Latin square and error. The intake of hay (P = 0.024), total DM (g/day, P = 0.001), NDF (P = 0.027) and supplement (P < 0.001) was higher for animals supplemented with PS. The total VFA and acetate ratio were not affected by the treatment (P > 0.05). The propionate ratio was higher for LMB (P = 0.016). The butyrate ratio (P = 0.005), valerate (P = 0.010) and A:P ratio (P = 0.017) was higher when the animals were supplemented with PS. The results indicate that the use of LMB improves propionate ratio and decrease the acetate:propionate ratio for steers fed low quality forage.