Effect of stage of maturity and addition of molasses on nutritive value of maize stover silage

Abstract

Maize silage (MS), high moisture maize stover silage (HMS), mature maize stover silage (SS) alone and with added molasses (SSM) were evaluated for chemical composition and feeding value in three trials with cattle and sheep. The silages were made in two successive years. Water was added to the stover to achieve approximately 60% moisture. Soya bean meal was added to the silages at feeding to provide 12% crude protein (Trial 1) and 10% crude protein (Trials 2 and 3). With the exception of hemicellulose, structural carbohydrate contents of HMS, SS and SSM were similar and all were higher than that found for MS (Year 1). Molasses addition to maize stover at ensiling enhanced fermentation by reducing the pH of SSM to that of MS and HMS. Daily dry matter (DM) intakes of steers (Trial 1, Year 1) were: MS, 78.9; HMS, 77.7; SS, 60.6; SSM, 79.6 g/kg 0.75 ( P<0.01). In Trial 2 (Year 1), DM intake of wethers was lowest for SS and was not significantly improved by molasses addition. Dry matter intake (g/kg 0.75) and DM digestibility (%) were: MS, 78.0 and 69.2; HMS, 60.1 and 59.3; SS, 46.4 and 51.0; SSM, 49.0 and 55.9, respectively. Also, DM intake (per unit of metabolic weight) and digestibility of the fibre fractions were higher for HMS than for SS. With the exception of cellulose, the digestibility of the fibre fractions and hemicellulose was higher ( P<0.05) for MS and HMS than for SS and SSM. Maize silage, HMS and SSM were compared in a performance trial with yearling ewes in Trial 3, Year 2. Chemical composition of silages was similar for the two years. However, in Year 2, pH of HMS (4.6) and SSM (4.5) was higher than in Year 1 (3.7 for both HMS and SSM). Ewes lost weight on the HMS and SSM silages, while only minimal gains were obtained in ewes fed on MS. Daily DM intakes were: MS, 57.2; HMS, 42.9; SSM, 47.5 g/kg 0.75 ( P<0.05). Harvesting maize stover at the high moisture stage, rather than when mature, increased nutrient availability of the structural carbohydrates to sheep, and also intake in cattle. Molasses addition to ensiled stover lowered silage pH and increased intake in cattle.