The potential of forage–maize intercrops in ruminant nutrition

Studies at the University of Reading (UK) compared silage quality, feed intake and digestibility of maize silage with maize–sunflower (MS), maize–kale (MK) and maize–runner bean (MRB) silage, when sunflowers, kale and runner beans represented 26, 7 and 16% of total silage dry matter (DM). All intercrop silages had higher crude protein values (MS, 137 g kg−1, MRB, 120 g kg−1, MK, 105 g kg−1) than maize (81 g kg−1). The neutral detergent fibre (NDF) and acid detergent fibre (ADF) contents were higher and the neutral cellulase gamminase digestibility (NCGD) values lower for MRB and MS compared with maize and MS silage. All silages fermented well with pH ranging from 3.9 to 4.2 and ammonia-N content of less than 100 g kg−1 total nitrogen (TN). An in vivo digestibility study with sheep showed no significant difference in voluntary feed intake between the four silages, with the highest and lowest values of 68 and 62 g DM (kg BW0.75)−1 per day being recorded for MK and MS silage. The highest and lowest values for in vivo DM digestibility (DMD) and organic matter digestibility (OMD) were recorded for MK and MS silages, with intermediate values for maize and MRB silage. The inclusion of all three intercrops significantly increased nitrogen digestibility when compared with maize silage. The metabolisable energy values for maize and MK silage were both substantially higher than those recorded for MRB and MS silage.