The objective of this work was to evaluate the effects of levels of nucleotides in diets for weanling pigs on performance, organs morphometry and histology of intestinal epithelium. One hundred and forty-four pigs weaned at 21 days of age and with 5.80 ± 0.16 kg initial live weight were used in a completely randomized experimental design with six diets, six replications per diet and four animals per pen (experimental unit). Diets were: Am _ antimicrobial: basal diet with 40 ppm of colistin sulfate and basal diet with 0, 150, 300, 450 and 600 ppm of nucleotides. At the end of the experimental period, one animal of each pen was slaughtered to evaluate morphometry of the organs and intestinal epithelium histology. From day 1 to day 14 of the experimental period, performance traits worsened linearly and for the total experimental period of 34 days, a linear reduction of final live weight was observed when levels of dietary nucleotides were increased. Pigs fed diet with colistin showed greater length of small intestine and lower villus height:crypt depth ratio (AV:PC) of duodenum when compard to those fed nucleotides. Also, a linear increase of relative weight of spleen, as well as a linear increase of AV:PC and linear reduction of crypt depth of duodenum were observed with the addition of nucleotides in the diet. Therefore, although the addition up to 600 ppm of nucleotides in complex diets did not improve performance, it improves morphometry of the organs and intestinal epithelium histology of weanling pigs.
antimicrobial; histology; intestine; morphometry; performance; swine
