Effect of storing total mixed rations anaerobically in bales on feed quality

Abstract

This experiment was conducted to evaluate the effect of storing total mixed rations (TMR) as wrapped round bales on feed quality. Nine separate TMR were produced that varied in forage to concentrate ratio [40:60, 50:50, 60:40; dry matter (DM) basis] and dry matter content (600 g DM/kg, 500 g DM/kg, 400 g DM/kg). Finished TMR were baled and wrapped with three layers of 750-mm wide stretch film. Fifteen bales were prepared for each treatment and three replicates at each sampling time. Another three bales for each treatment were made for temperature monitoring. After 0, 3, 7, 15, and 30 d storage, the bales were weighed and the area of the surface covered with mould was ranked. Core samples of bales were taken using a modified boring device at the same time for quality analyses. There was little temperature response over the 30 d storage period in any of the bales monitored. Visible mould spots were only appeared on the surface of baled TMR at 30 d. Decrease of DM content took place during the storage phase of baled TMR and loss of DM decreased (P<0.05) in an inverse relationship with initial DM content. Concentrations of crude protein, ether extract, and ash showed continuous increase (P<0.05; P<0.01; P<0.001) after TMR stored using baling technology. The neutral detergent fiber (NDF) and acid detergent fiber (ADF) content exhibited a fluctuation and lignin showed increase (P<0.01; P<0.001) along with the storage time increased. The pH of baled TMR decreased (P<0.001) as stage of storage time increased. The fermentation products, e.g., ammonia nitrogen (NH 3-N), lactic acid, acetic and propionic acid, were all showed increase (P<0.001) along with the increase of storage time, and NH 3-N and volatile fatty acid concentrations were not very high at the end of storage. The baled TMR studied in this research were of relatively high nutritive value, had low proteolysis and no putrefactive fermentation occurred during the whole storage period of baled TMR. Baled TMR may be a good choice for small-scale farms to use TMR technique in their dairy production.