In vitro and in sacco determining the nutritive value of button mushroom stipe and its application in growing lambs diet

Abstract

Feed shortage is one of the major challenges in livestock production systems in the arid and semi-arid regions of the world. Hence, wastes of nutritional value from the agro-alimentary industry could be considered as by-product feedstuffs, reducing diet costs in these regions. The current study aimed at determining in vitro and in sacco nutritive value of button mushroom stipe (BMS) and investigating its potential in growing lambs diet. For this purpose, three experiments (Exp.) were conducted. Ruminal degradability characteristics, and gas production kinetics, and energetic value of BMS compared with alfalfa were determined by the nylon bag and gas production techniques in Exp.1 and Exp.2, respectively. In Exp.3, 24 Mehraban growing lambs were assigned randomly to one of the three dietary treatments: (1) the basal ration without BMS (CTRL); (2) and (3) inclusion of 10 and 20% (DM basis) of BMS in the basal ration (BMS10 and BMS20, respectively), to determine their growth performance and the rations digestibility. The soluble (a) and slowly degradable (b) fractions, and degradation rate of ‘b’ fraction of the BMS crude protein (CP) was 43, 59%, and 0.034, respectively. The metabolisable energy (ME) content of BMS was 20.6% lower than that in alfalfa. The inclusion of BMS in the ration of lambs did not affect their growth performance, but reduced diet cost by 7.2 and 14.5% in BMS10 and BMS20, respectively. The BMS tended to increase (p = .089) the blood total protein in lambs fed BMS10 and tended to decrease (p = .07) alkaline phosphatase (ALP) in BMS-based diets. These results reveal that BMS has a slow ruminal degradability and fermentation that can reduce diet cost by partially replacing conventional feedstuffs in the ruminant diet without adversely affecting their health and performance. Highlights The button mushroom stipe (BMS) by-product has relatively high crude protein and acceptable energy contents with a slow ruminal degradability. Including BMS in the diet of growing lambs reduced diet costs, while improving fairly their growth performance, implying that BMS can be considered as a cost-effective by-product feedstuff in a ruminant diet. The inclusion of BMS in the diet of lambs decreased ruminal ammonia production, which can reduce the environmental impact of ruminant production systems.