Effect of season of planting (and harvesting) of sugar cane on the nutritive value of the juice for fattening pigs

摘要

Theaimsofthisstudyweretodeterminetheeffectofthequalityofsugarcanejuice(sugarconcentration),asinfluencedbyseasonofharvesting,ontheperformanceoffatteningpigsgiventhisfeedasthebasisoftheirdiet.Thehypothesistobeverifiedwasthatthefeedingvalueofthejuiceforpigswouldbelowerforsugarcaneharvestedintherainyseasoncomparedwithcaneharvestedinthedryseason.ThesugarcaneusedintheexperimenthadbeenplantedatmonthlyintervalsbetweenJuly1994and1995inplotsmeasuring800m2.Thereweretwotreatmentsappliedineachoftwotrialswhichwerecarriedoutconsecutivelyinthewetanddryseasons.Thetreatmentswere:SCJ:Sugarcanejuiceandproteinsupplement;Control:Brokenriceandproteinsupplement.ThetrialsweredonewithdifferentlotsofpigsfromJuly1995toNovember1995(Trial1;wetseason)andfromDecember1995toMay1996(Trial2:dryseason).Fourgroupseachof3crossbredpigs(LargeWhitexMongCai)wereallocatedtoeachofthetwotreatmentsineachofthetrials.Theinitialweightatthestartofeachtrialwas20kgonaverageandthetrialcontinueduntilthepigsreachedanaverageof70kgliveweight(trial1)and65kgliveweight(trial2).Thereweremarkeddifferencesinthesugarcontentofthejuicewhichwas40%higherinthecanestalkharvestedinthedryseason(°Brixof22)thaninthewetseason(°Brix16).Intakeofjuicewashigherinthewetseasonbutnotenoughtocompensateforthelowerbrixcontentasintakeofsugarswas1.05kg/dinthewetseasoncomparedwith1.22kg/dinthedryseason.Thegrowthrateofpigsfedcanejuiceinthewetseasonwas28%lowerthanforthosefedthecontroldietand20%lowerthanforpigsfedcanejuiceinthedryseason.Inbothseasonsthefeedconversionratewasworseforsugarcanejuicethanforthebrokenrice.Pigsfedcanejuiceinthewetseasonhadfattercarcassesthanthecontrolanimalsbuttherewerenodifferencesbetweendietsinthedryseason.Thelowercontentofsugars(°Brix)inthejuiceappearedtobethereasonforthelowergrowthratesandfattercarcassesofpigsfedjuicefromwetseasoncane.