The effect of shrimp shell waste on ruminal bacteria and performance of lambs

This study has focused on the response of lambs and its ruminal bacteria to diets with 0, 15 or 25% of shrimp shell waste (SSW). Fifteen lambs (Suffolk×Corriedale; average BW, 21.74 kg) were allotted at random (five per treatment) to diets calculated to contain 0, 15 and 25% of SSW (DM basis) in a growth and digestion trial during 72 days. Average feed intake was similar between treatments, but at the end of the experiment (periods 4 and 5) feed intake decreased (P<0.05) in lambs fed 25% SSW. Weight gain showed a linear decrease (P<0.05) in lambs fed with increasing levels of SSW. However, average feed conversion was similar among treatments. In vivo digestibility was lower (P<0.05) in the group fed 25% SSW, compared to those fed 0 and 15% for DM, CP, ADF, and NDF. Concentration of total, cellulolytic and chitinolytic bacteria were measured using anaerobic culture techniques. Bacteria concentration were estimated on days 30, 60 and 72 of the experimental period. Concentrations of total and cellulolytic bacteria were not affected by treatments. In contrast, chitinolytic bacteria concentration increased (P<0.05) in lambs fed 15 or 25% SSW, compared with control diet. This increase in chitinolytic bacteria was observed 60 days after feeding SSW. Results indicate a very slow adaptation of ruminal microorganisms to diets containing chitinous compounds. It is concluded that SSW can be used (up to 15%, DM basis) in diets for growing lambs, without a negative effect on animal performance. The use of a ruminal inocula made of chitinolytic bacteria to decrease the adaptation period for the animal and its ruminal microorganisms should be studied.