Evaluation of scallop viscera silage as a high-protein feedstuff for growing-finishing swine

Abstract

The nutritional value of scallop viscera silage was assessed when it formed a high proportion of the diet for growing—finishing swine. A secondary objective was to determine the possible carryover of cadmium contained naturally in the viscera into various tissues of these swine. Scallop viscera is a byproduct of Calico scallop ( Aequipecten gibbus) shellfish processing and contains 70–85% moisture and, on a dry matter (DM) basis, 70–85% crude protein. The scallop viscera silage was prepared by mixing minced, fresh viscera with formic acid (3.5% w/w) and placing the mixture in airtight containers. The viscera silage averaged 19% DM and contained, on a DM basis, 85% crude protein, 2.5% crude fat, 6.7% ash, 1.8% Ca, 0.7% P, 5.8% lysine and 7.5 mg kg −1 Cd. Twenty pigs (27 kg mean live weight) were divided between two treatments, 0 or 24% dietary levels of silage, with two pigs per pen. The pigs were fed on grower diets (0.75% lysine, 89% DM basis) to 52 kg and then on finisher diets (0.61% lysine). The viscera silage supplied 33 and 41% of the lysine in the grower and finisher diets, respectively. The viscera silage had no detrimental effect ( P > 0.10) on average daily gain, feed intake or feed-to-gain ratio. Apparent digestibility of DM, N and energy of the grower or finisher diets was also not affected. Cadmium accumulation was noted in kidney (1–4 mg kg −1) and liver tissues from pigs given viscera silage. Very little accumulation was noted in muscle (masseter) tissue examined. In addition, no differences in resulting carcass composition or meat quality characteristics were noted as a result of treatment. The ensiling of scallop viscera with formic acid and its subsequent utilization as a protein feed supplement for swine diets may offer a practical means of utilization of this waste material.