In vitro and in situ estimation of ruminal and intestinal digestion of lobster and crab shell meal

Abstract

Objective

This experiment compared in vitro dry matter digestibility (IVDMD), in vitro intestinal protein degradability, and in situ degradability of lobster shell meal (LM), crab shell meal (CM), soybean meal (SBM), and blood meal (BM), and chitin degradability of LM and CM.

Materials and methods

The 48-h IVDMD was determined in rumen fluid. For in situ DM and CP degradability, 4 Holstein cows were used to test the degradation rates of SBM, BM, LM, and CM. Samples were removed after 2, 4, 8, 12, 24, and 48 h. Protein fractions and degradation rates were determined. Fraction A was the washout before rumen suspension. Fraction C was the material remaining after 48 h. Fraction B was the initial sample − (A + C). The CP degradation rate was calculated by converting fraction B to the natural log and calculating the slope. The effective CP degradability was calculated by multiplying the sum of fractions A and B by the CP degradation rate and dividing that by the sum of the CP degradation rate and the outflow rate (2%, 5%, or 8%). For intestinal digestibility, Dacron bags (Ankom R510, pore size 50 μm, Ankom Technology) were removed from the rumen at 12 h, incubated with HCl and pepsin for 1 h, and then incubated for 12 h with protease and buffer to mimic intestinal digestion. After removal, sample bags were dried for 48 h at 55°C.

Results and Discussion

Soybean meal was more soluble than other feeds, and BM tended to be less soluble than LM or CM. Similarly, 12-h DM degradability was greater for SBM than for BM, LM, and CM; and BM was less than LM and CM. Intestinal DM digestibility was similar among feeds. Blood meal intestinal digestibility was estimated to be more than that of LM or CM. Rumendegradable protein was greater for SBM than for the other feeds. Blood meal was more degradable than LM and CM. Protein fraction A was similar for LM and CM, whereas fraction B and fractions A + B tended to be greater for CM than LM and fraction C tended to be greater for LM than CM. Soybean meal had greater fraction B and the sum of fractions A and B than the other feeds, and lesser fraction C. Degradation rates were greater for SBM than they were for the other feeds. Soluble chitin was greater for CM than LM, but degradability rates at 12 h and 48 h were similar.

Implications and applications

Results indicate that crustacean shell wastes may be used in cattle diets. More research should be conducted on feeding them to cattle.