The potential of forage-maize intercrops in ruminant nutrition

Studies at the University of Reading (UK) compared silage quality, feed int ake 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 interc rop silages had higher crude protein values (MS, 137 g kg(-1), MRB, 120 g k g(-1) MK, 105 g kg(-1)) than maize (81 g kg(-1)). The neutral detergent fib re (NDF) and acid detergent fibre (ADF) contents were higher and the neutra l cellulase gamminase digestibility (NCGD) values lower for MRB and MS comp ared with maize and MS silage. All silages fermented well with pH ranging f rom 3.9 to 4.2 and ammonia-N content of less than 100 g kg(-1) total nitrog en (TN). An in vivo digestibility study with sheep showed no significant di fference in voluntary feed intake between the four silages, with the highes t and lowest values of 68 and 62 g DM (kg BW0.75)(-1) per day being recorde d for MK and MS silage. The highest and lowest values for in vivo DM digest ibility (DMD) and organic matter digestibility (OMD) were recorded for MK a nd MS silages, with intermediate values for maize and MRB silage. The inclu sion 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 a nd MS silage. (C) 2000 Elsevier Science B.V. All rights reserved.