Investigation on using spent wheat straw compost of Agaricus bisporus mushroom residue in the diet of fattening calves

This study was conducted to determine the effects of adding spent wheat straw compost from Agaricus bisporus mushroom in fattening calves diet. Spent compost was provided from a mushroom production farm and the remaining particles were separated from the straw after mushroom cultivation. Spent straw compost was sun dried and chemical composition analyzed for DM, OM, CP, CF, NDF, ADF, Ca and P. Fifty male Holstein calves with initial average weight of 321± 18 kg were randomly divided into experimental and control groups. Diets were adjusted based on the average weight of the calves and NRC recommendation. Spent straw compost was used in the experimental group at 10% of the diet. The experimental period was 180 days. The animals were fed three times daily with total mixed ration offered ad libitum. Feed intake, body weight changes, feed conversion ratio and feed cost per kg bodyweight were determined and compared. Results showed that feeding spent straw compost did not have any significant effects on daily weight gain, feed intake and feed conversion ratio of feedlot calves. Average daily gain in the control and experimental groups were 1204 and 1150 g, respectively. Average daily feed intake was 9.8 and 10.1 in control and experimental group respectively and feed conversion ratio of control and experimental group were 8.2 and 8.8 respectively. The use of spent compost slightly increased the cost of the diet as well as feed prices per kg increase in live weight in the experimental group. According to the findings of the present study, compost straw can be include up to 10 percent of the TMR form diet of finishing calves, but its economic advantage is dependent on access and cost.