Abstract
Histological responses of the intestine are key for evaluating nutritional value of feed ingredients, since the organ is not only the chief site of feed digestion and nutrient absorption but also plays an important immunological function. Histomorphological alterations were evaluated in the intestine of juvenile striped catfish, Pseudoplatystoma fasciatum, fed diets containing 0 (control), 10 or 20% inclusion of lyophilized bovine colostrum (LBC), as source of protein or bioactive peptides, for either 30 or 60 days. Fish fed 20LBC presented at 60d a distinct pattern of macrophages and, some of them, higher number of vacuoles in rectum mucosa. The thickness of the muscle layer (TML) in fish fed diets with LBC was higher in the first portion of medium intestine than fish fed 0LBC. All fish presented significant increase of TML in the second portion of medium intestine along feeding period, but fish fed 20LBC had smaller values of TML than those of fish fed 0 and 10LBC which might be related to the higher intestinal coefficient found for this group. The TML of rectum was higher just for fish fed 10LBC. Dietary LBC altered morphometrical features of juvenile striped catfish intestine and possibly induced inflammatory reaction in the rectal mucosa, as a function of level of inclusion, feeding period and segment of intestine analyzed.
Highlights
This study evaluates the occurrence of histomorphological alterations in the intestine of striped catfish, fed diets containing varying levels of bovine colostrum as protein and bioactive peptides source
Fish fed diet 20LBC presented at day 60 a distinct pattern of macrophages, which predominate in the apical portion of intestinal folds, exhibited a distinct staining pattern, and were apparently bigger than those found in fish fed the control or 10LBC diets (Figure 1)
Some fish fed the 20LBC diet presented at day 60 higher incidence of vacuoles in the intestinal mucosa (Figure 2)
Summary
Knowledge on anatomical and morphophysiological features of fish digestive tract set bases for the study of fish nutrition (Datta Munshi and Dutta, 1996; Evans et al, 2005; Pezzato et al, 2004). Aslaksen et al (2007), Romarheim et al (2008), Urán et al (2008) and Øverland et al (2009), have regarded histological responses of the intestine as a supplementary tool to evaluate the nutritional value of an ingredient, since the organ is the chief site of feed digestion and absorption of nutrients and plays an important immunological function (Buddington et al, 1997).The bovine colostrum is a complex food source, with high contents of proteins and a diversity of biologically active molecules, such as growth factors, especially insulin-like growth factors (IGFs) (Blum and Hammon, 2000; Foley and Otterby, 1978; Pakkanen and Aalto, 1997). This study evaluates the occurrence of histomorphological alterations in the intestine of striped catfish, fed diets containing varying levels of bovine colostrum as protein and bioactive peptides source.
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