532conccntrations at 0 8 M rlor M. O\,1 cligestibilitv increased iinearlr, with reducing F : C raiios at both 0.8 \,1 and \1, the r\ri, relationships had the s.rme slope but had sisnificantlr' diffe¡cnt {P < 0 05) intercepts (0.961 anrl 0.9-16 fo¡ 0.3 \,1 arrd M respectii.elr,).Meth;rne procluction per ke O\1 apparentlv digested clecreasi,.j rljtir decreasit.rg F: C ratio linearlr. (no interactions) resarJless oi Itrvl oi nt.rinicnilnrr.. tlr\)ujlr tlli. iv.l..iqrriti..rnL,¡l -O.l ",r1, t,,. 0I M. It is corrclucled that plane of nut¡iiiou anci F:C r¡iitt c.ln infiuence apparcnt OM ciigestibilitr' ¿nd mcthane produciion rvhcn gr.'is.s silage is suppler-rrcnted t'ith FM. Implications are tirat methane procluction irom FM alone over tlte inclu:ion r;rngc studied can be cstimatccl from the methane produced f¡or.n tl-le mixecl cliets.82. The use of sheep to predict methane production by cattle fed grass silage-based rations C. J. Ner.vboldi, A. R. Mossr, G. S. lr,'lollirrsorrr and C. C.
Harbronrillo¡r'ctf ltcs¡ar-c/¡ l¡tstitut¿, BttcksbtLni, AItcrd¿cn AB2 9SB::AD,4S Dnit t¡ Rcsctrclt Cuttrc, Facd Etttltttttit'tn LInit, Str¡t.it¡rtl o,r ,4i)o¡r CV-l; 9RQ; r-S¡offl-s/¡ Agt ícrrltrLrnl Stntisticnl -Scr-¡,iccs, B tL cksh tt r n, Altcr dt't'tt,4tsl 9-SB Irrcreasirrg c()nccrn r¡r'cr the róic of grccrrhouse gases in glob¡l rr'.lrming has led to ¿ rentrr.ecl jltcrest rn r.nr¡clcls ior prerlictirrg mr.thane pr()ductiolr iu nrlrtill¿nts. For economic reasons it n.ould