Use of restricted broken rice in duckweed based diets for fattening Common and Muscovy ducks

摘要

Twobreedsofducks(ImprovedCommonducksandlocalMuscovy)werefattenedwithlocalfeedresourcesintwosequentialtrialsattheDuckExperimentalFarmofCanthoUniversity.Thebasaldietwasbrokenricegivenadlibitum(BRAL)orrestrictedto80(BR80)or60(BR60)g/day.Oneachofthesetreatmentstheduckshadfreeaccesstofreshlyharvestedduckweedfrompondsfertilizedwithbiodigestereffluentandcontaining39%proteininthedrymatter.Therewere54ducksofmixedsexesoftheCommontypeandtheywerefedfrom28to63daysofageontheexperimentaldiets.Agroupofsixduckswasallocatedtoeachof9pensgiving3replicatesofeachdietarytreatment.ThelocalMuscovyducks(45)wereallfemales.Theywereallocated5perpentogivethesamenumberofreplicatesasfortheCommonducksandfattenedfrom28to70days.CommonducksgrewatthesamerateastheMuscovybutatetwiceasmuchduckweed.Theirfeedconversionwaspoorer.DecreasingtheofferlevelofthebrokenricehadnoeffectongrowthandcarcasstraitsoftheCommonducksbutslightdepressedgrowthrateandreducedweightsofchestandthighmuscleinthecarcass.WhenricelevelswererestrictedtheMusclyducksappearedlessabletocompensatebyeatingmoreduckweedascomparedwiththeCommonducks.Afeedingsystemofrestrictedlevelsofbrokenrice(60to80g/day)withfreeaccesstofreshduckweedappearstobeappropriatefortheCommontypeofducktypicallyusedforforagingonricefieldsthroughoutVietnam.MoreresearchisneededinordertoascertainiftheapparentcapacityofCommonduckstoeatlargequantitiesofduckweedreallyisacomparativeadvantageand,ifso,howthiscanbestbeusedtoimprovetheeconomicbenefitstosmallscalepoorfarmers.