In vitro fermentation pattern and acidification potential of different sources of carbohydrates for ruminants given high concentrate diets

• Main Authors: Zahia Amanzougarene, Susana Yuste, Antonio de Vega, Manuel Fondevila
• Format: Article
• Language: English
• Published: Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria 2017-07-01
• Series: Spanish Journal of Agricultural Research
• Subjects: incubation pH; gas production; sugarbeet pulp; sucrose; citrus pulp; wheat bran
• Online Access: http://revistas.inia.es/index.php/sjar/article/view/10753

The in vitro fermentation pattern of five sources of carbohydrates of differing nature (maize grain, MZ; sucrose, SU; wheat bran, WB; sugarbeet pulp, BP; and citrus pulp, CT) under conditions of high concentrate diets for ruminants was studied. A first 8 h incubation trial was performed under optimal pH using inoculum from ewes given a fibrous diet, to compare fermentative characteristics of substrates. As planned, incubation pH ranged within 6.3 to 6.6. The gas produced from CT was higher than MZ, SU and BP from 4 and 6 h onwards, and at 8 h, respectively (p<0.05). There were no differences (p>0.05) on total volatile fatty acid (VFA) concentration, nor on acetate or propionate proportions, but butyrate was lowest (p<0.05) with CT and BP. The second incubation trial was performed in a poorly-buffered medium, with inoculum from ewes given a concentrate diet. All substrates showed a gradual drop of pH, being lowest with SU after 4 h (p<0.05). Throughout the incubation, gas production was highest with CT and lowest with MZ and BP (p<0.05). Total 8 h VFA concentration was higher with CT than BP, SU and MZ (p<0.05). Acetate proportion was higher, and that of propionate lower, with BP than WB (p<0.05), butyrate proportion being higher with MZ and WB than with BP and CT (p<0.05). Lactic acid concentration was higher (p<0.05) with SU than WB and BP. Fermentation characteristics and acidification potential of feeds depend on the nature of their carbohydrate fraction, and must be considered for practical applications.