Enzymatic effects of Pleurotus ostreatus spent substrate on whole-plant corn silage and performance of lactating goats

Pleurotus ostreatus (oyster mushroom) synthesizes enzymes that degrade lignin, cellulose, and hemicellu-lose. The objectives of this study were to evaluate the effect of Pleurotus ostreatus spent substrate (POSS) on whole-plant corn silage (WPCS) chemical composition, antioxidant capacity, lignin monomers, and in vitro di-gestibility, as well as the performance of lactating goats fed corn silage treated with different levels of POSS. In experiment 1, 4 levels of lignocellulolytic enzymes were tested in a complete randomized design: 0, 10, 20, and 30 mg of lignocellulosic enzymes per kilogram of fresh matter, 4 replicates per treatment (vacuum-sealed bags). The bags were opened 60 d after ensiling. In experiment 2, corn silage treated with 3 enzyme levels (0, 10, or 30 mg/kg of fresh matter) was fed to lactating goats as part of the total mixed ration. Nine lactating Saanen goats (62.68 +/- 7.62 kg BW; 44 +/- 8 d in milk; 2.91 +/- 0.81 kg of milk/day, mean +/- SD) were assigned to three 3 x 3 Latin squares. Data were analyzed us -ing the GLIMMIX procedure of SAS (version 9.4, SAS Institute Inc.), and means were compared by linear and quadratic orthogonal contrast. In experiment 1, neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin, and cellulose quadratically decreased in the WPCS treated with POSS. At the nadir point, POSS decreased NDF by 14.1%, ADF by 19.5%, lignin by 9.07%, and cellulose by 22.1% compared with the untreated silage. Therefore, POSS led to a quadratic increase in in vitro dry matter digestibility of WPCS (+8.88% at the vertex) compared with the untreated silage. In experiment 2, POSS quadratically increased the in vivo total-tract ADF digestibility. Also, the con-centration of polyphenols in the milk of goats linearly increased with the addition of POSS, and no differences were observed among treatments for milk yield and composition. In summary, adding 10 mg of lignocellulo-lytic enzymes from POSS per kilogram of fresh matter of whole-plant corn at ensiling had a more evident re-duction in lignin and cellulose concentration, leading to greater in vitro digestibility, as well as greater in vivo ADF digestibility; however, milk yield was not different among treatments.

Automated summary

The study found that treating whole-plant corn silage with Pleurotus ostreatus spent substrate (POSS) can significantly impact the chemical composition and digestibility of the silage, as well as improve in vivo digestibility in goats. Additionally, the addition of POSS led to an increase in polyphenol concentration in goat milk.