Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 7/25/2001
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: A dual flow continuous culture system was used to investigate the effects of replacing dietary starch with sucrose at various concentrations on nutrient digestibility and ruminal fermentation. Four diets were evaluated using a completely randomized design during four replicates. Diets were formulated to contain on a DM basis 40% alfalfa silage, 20% corn silage, 20.5% rolled high moisture shelled corn, 9% soybean meal, 2% fat, 1% vitamin-mineral supplement, 7.5% supplemental nonstructural carbohydrate (NC) with a nutrient composition of 16.7% CP, 1.7 Mcal/kg NEl and 29% NDF. The NC fed in the four diets was: A) 7.5% starch, 0% sucrose: B) 5% starch, 2.5% sucrose; C) 2.5% starch, 5% sucrose; and D) 0% starch, 7.5% sucrose. Four continuous culture fermenters were used. On day 7-9 effluents were collected daily and composited for nutrient digestibility determination and yo analyze ammonia-N and VFA. No differences were observed in pH throughout the day ranging from 5.67 to 6.21 with an overall mean of 5.97 +/- 0.08. Ammonia-N concentration averaged 9.23 mg/100ml +/- 0.66 with a trend (P less than 0.11) for a positive linear effect with increasing sucrose in the diet. Apparent DM digestibility was not different among treatments and averaged 46.8% +/- 1.5. NDF digestibility increased linearly when sucrose was added to the diet and at the highest inclusion was 66.1% vs. 60.9% when compared to the all starch diet. Total VFA was not different among treatments and averaged 103.9 +/-0.66 mM. Branched chain VFA concentration decreased linearly with increasing sucrose in the diet. Bacterial N content was not affected by treatment. Replacing corn with sucrose in the diet resulted in a change in microbial fermentation such tha t NDF digestibility was enhanced.