The quality of commercial wheat silages in Israel

Wheat silages are the major roughage for high-producing lactating dairy cows in Israel; therefore, their quality is important. The main objective of the current study was to determine the preservation status and nutritional quality of commercial wheat silages in Israel. An additional objective was to develop predictive equations for dry matter digestibility (DMD) and neutral detergent fiber digestibility (NDFD) based on chemical composition of the silages, which would permit estimation of the digestibility from chemical composition. A total of 143 commercial wheat silages were sampled and analyzed for 3 yr. Fourteen random samples that were not included in the regression analysis were used to validate the equations by the bias and error of the model. Results revealed that wheat silages were quite sensitive to aerobic exposure; additives resulted in some improvement of the aerobic stability. After choosing the significant terms from ash, crude protein (CP), NDF, acid detergent fiber (ADF), and acid detergent lignin (ADL) by PROC STEPWISE of SAS, the following prediction equations were obtained from all 143 samples: DMD = 86.3 + (0.70 x CP) - (0.46 x ADF) - (1.67 x ADL); and NDFD = 20.3 + (1.00 x CP) + (1.16 x NDF) - (0.88 x ADF) - (2.25 x ADL). The bias and the error of the prediction model for DMD were approximately 0.006 and 0.065, respectively; the bias and error for NDFD were approximately 0.007 and 0.118, respectively. It was concluded that the prediction model for DMD was quite adequate, whereas that for NDFD was less acceptable.