Addition of inulin, alfalfa and citrus pulp in diets for piglets: Influence on nutritional and faecal parameters, intestinal organs, and colonic fermentation and bacterial populations

• Inulin, fresh alfalfa and fresh citrus pulp were included in diets for piglets.
• In vitro gas volume was higher in the groups receiving fibre sources.
• Some negative aspects related to nutrients absorption and N utilization were found.

The effects of the inclusion of inulin, fresh alfalfa and fresh citrus pulp in diets for piglets on intake, nutritional and faecal parameters, digestive tract size, fermentation kinetics and colonic microbial populations was evaluated. Twenty-four cross-breed piglets (initial BW: 9.75±1.63 kg) in a randomized complete block design were housed in metabolic cages and assigned to one of 4 treatments: 100% corn and soybean meal control diet (CON), 97% CON+3% inulin (INU), 95.5% CON+4.5% fresh alfalfa (ALF) and 95.5% CON+4.5% fresh citrus pulp (CIT). The experiment consisted of a 12 d adaptation period followed by 12 d for samples collection. The last 2 days of the experiment all animals were euthanized, the digestive tract of each animal was removed and an individual sample of colonic digesta was collected. Feed intake tended to be lower in the fibre supplemented groups (P=0.098), and was lower in ALF than in CIT (P=0.026). Groups receiving fibres tended to excrete more faeces (P=0.088), evacuated softer faeces (P=0.041) and presented a lower digestibility of CP (P=0.003). Retention of N was higher in the CON group than in fibre containing diets (P=0.009), and lower for ALF than for CIT (P=0.034). Colonic pH was lower in CIT and ALF treatments than in INU (P=0.016), in vitro gas volume was higher in the fibre-supplemented groups than in CON (P=0.048), but no differences between colonic bacterial counts were noticed among treatments. From the data obtained we conclude that the addition of fresh alfalfa and citrus pulp produce some beneficial effects in terms of promoting an increase in the hindgut fermentation, but negative aspects related to poorer nutrients absorption and N utilization can limit the usage of these fibrous sources.