Effects of Replacing Extruded Maize by Dried Citrus Pulp in a Mixed Diet on Ruminal Fermentation, Methane Production, and Microbial Populations in Rusitec Fermenters

• Published in: Animals (Basel) 2020-07, Vol.10 (8), p.1316
• Main Authors: García-Rodríguez, Jairo, Saro, Cristina, Mateos, Iván, González, Jesús S, Carro, María Dolores, Ranilla, María José
• Format: Article
• Language: English
• Subjects: Acetic acid; Alfalfa; ARISA; Bacteria; Barley; Cereals; Citrus fruits; citrus pulp; Corn; Deoxyribonucleic acid; Diet; DNA; Effluents; extruded maize; Extrusion; Fermentation; Fermenters; Fungi; Liquid phases; Methane; microbial protein synthesis; Microorganisms; Nutritional aspects; Populations; Propionic acid; Protozoa; qPCR; Sheep
• ISSN: 2076-2615; 2076-2615
• DOI: 10.3390/ani10081316

Citrus pulp is a highly abundant by-product of the citrus industry. The aim of this study was to assess the effects of replacing extruded maize (EM; 20% of total diet) by dried citrus pulp (DCP; 20%) in a mixed diet on rumen fermentation and microbial populations in Rusitec fermenters. The two diets contained 50% alfalfa hay and 50% concentrate, and the same protein level. Four Rusitec fermenters were used in a cross-over design with two 13-d incubation runs. After 7-d of diet adaptation, diet disappearance, fermentation parameters, microbial growth, and microbial populations were assessed. Fermenters receiving the DCP showed greater pH values and fiber disappearance ( < 0.001) and lower methane production ( = 0.03) than those fed EM. Replacing EM by DCP caused an increase in the proportions of propionate and butyrate ( < 0.001) and a decrease in acetate ( = 0.04). Microbial growth, bacterial diversity, and the quantity of bacteria and protozoa DNA were not affected by the diet, but the relative abundances of fungi and archaea were greater ( < 0.03) in solid and liquid phases of DCP fermenters, respectively. Results indicate that DCP can substitute EM, promoting a more efficient ruminal fermentation.