PSXII-12 Effects of compost environment on bone degradation of livestock mortality compost

Abstract Livestock mortality composting is an effective carcass disposal option for many producers. One issue that arises once the compost has gone through its curing process is that large, dense bone is present in the compost. Producers are forced to sift out the bone and dispose of it in alternative ways. Objectives of this study were to determine weight degradation of post-composted bone when subjected to re-composting using either manure-only (i.e., control; n = 3) or offal and flaked hay (i.e., treatment; n = 3) as additional nitrogen and carbon sources, respectively. All materials used for the 125-d study were sourced from the CSU, Chico University Farm. Control compost mounds were constructed in three layers (i.e., manure-bedding mix, bone, and manure-bedding mix) whereas the treatment compost mounds were constructed using the layering method consisting of a flaked hay base, manure-bedding mix, bone, boneless offal treatment, manure-bedding mix, and flaked hay cap. Offal compost mounds used boneless butcher waste (i.e., bovine, ovine, and porcine digestive tracts). Each compost mound included 1 skull, 2 pubis, 2 mandibles, 3 scapulas, 3 vertebrae, 4 femurs, 8 metacarpus or metatarsus, and 10 ribs. Bones were weighed and recorded on d 0 and d 125. Temperature was monitored weekly. Data were analyzed as a completely randomized design using a single factor analysis of variance. There was no difference (P > 0.05) between control and treatment compost mounds for total bone weight at d 0. Results also showed that there was no difference between the control and the treatment on d 125 (17.86 ± 1.31 kg vs. 15.76 ± 0.88 kg; P = 0.26). These results suggest longer composting periods may be necessary to see degradation of bone by weight loss.