?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Adc&rft.title=Organic+dairy+cows%3A+milk+yield+and+lactation+characteristics+in+thirteen+established+herds+and+development+of+a+herd+simulation+model+for+organic+milk+production&rft.creator=Hovi%2C+M&rft.subject=+Education%2C+extension+and+communication&rft.subject=+Dairy+cattle&rft.subject=+Animal+husbandry&rft.description=As+a+consequence+of+organic+standards+and+principles%2C+organic+dairy+producers+are+frequently+faced+with+a+different+set+of+management+considerations+than+those+found+in+conventional+dairy+systems.+The+broad+objective+of+this+study+was+to+examine+in+detail+the+production+characteristics+of+13+well-established+organic+dairy+herds%2C+and+to+relate+these+to+the+specific+conditions+that+exist+within+organic+dairy+farming.%0D%0A%0D%0AMonthly+milk+records+for+13+organic+herds+for+three+years+were+collected+and+converted+into+a+Microsoft+Access%C3%AF%C2%83%C2%A4+database%2C+using+InterHerd%C3%A2%C2%84%C2%A2+(Agrisoft+Plc.%2C+UK)+herd+management+software.+The+data+were+sorted+and+analysed+using+the+InterHerd%C3%AF%C2%83%C2%A4-herd+management%2C+Excel+for+Windows%C3%A2%C2%84%C2%A2+and+Statistix+for+Windows%C3%AF%C2%83%C2%A4+software+programmes.+Estimated+parameters+were+used+to+examine+the+importance+of+two+important+indicators%3A+lifetime+yield%2Flactation+length+and+economic+efficiency.+To+assess+the+first%2C+a+spreadsheet+model+based+on+the+Wood's+lactation+curve+was+developed.+With+regard+to+the+latter%2C+a+model+calculator+was+used.+Five+herds+were+chosen+for+case+studies%2C+that+examined+the+farm+performance+by+using+InterHerd%C3%A2%C2%84%C2%A2-generated+data+and+by+interviewing+the+producer+retrospectively+and+asking+him+to+comment+on+the+data.%0D%0A%0D%0AResults%0D%0AMilk+yield+and+lactation+characteristics%0D%0A%C3%AF%C2%82%C2%A7+The+13+established%2C+organic+herds+were+characterised+with+relatively+low+yields%2C+but+herd+variation+was+great%3A+from+a+total+lactation+yield+of+5%2C100+kg+to+7%2C000+kg.+Milk+fat+and+protein+content%2C+lactation+length+and+individual+cow+SCC+means+were+similar+to+those+reported+in+conventional%2C+milk+recorded+herds.%0D%0A%C3%AF%C2%82%C2%A7+Lactation+yields+increased+up+to+the+third+lactation%2C+whereas+persistency+of+lactations+decreased+up+to+the+third+lactation.+This+pattern+followed+similar+patterns+reported+in+conventionally+managed+herds.+Similarly%2C+somatic+cell+counts+increased+with+parity%2C+mimicking+similar+phenomenon+reported+in+conventionally+managed+dairy+cows.%0D%0A%C3%AF%C2%82%C2%A7+Length+of+lactation+and+lactation+persistency+were+associated+with+month+of+calving%2C+with+autumn+calving+cows+tending+to+have+shorter+lactations+with+better+persistency.+This+phenomenon+was%2C+however%2C+confounded+with+parity.%0D%0AFertility%0D%0A%C3%AF%C2%82%C2%A7+It+is+concluded+that+fertility+performance+in+terms+of+culling+for+fertility+and+mean+calving+intervals+were+better+in+the+organic+survey+herds+when+compared+with+existing+data+from+conventionally+managed+UK+dairy+herds.+Good+fertility+performance+even+in+the+highest+yielding+organically+managed+cows+suggests+that+early+lactation+energy+deficit+may+not+be+a+major+problem+in+these+herds.+It+is+also+suggested+that+financial+impact+of+high+number+of+services+per+conception%2C+as+observed+in+majority+of+the+survey+herds%2C+may+be+insignificant+as+the+main+losses+caused+by+poor+fertility+are+attributable+to+culling+and+prolonged+calving+intervals.+%0D%0AHerd+models%0D%0A%C3%AF%C2%82%C2%A7+Herd+productivity+indices+were+generated%2C+using+an+existing+model+based+on+a+measure+of+feed+conversion+efficiency+at+the+herd+level.+The+advantage+of+using+this+approach+in+the+estimation+of+productivity+is+that+it+takes+full+account+of+the+entire+feed+input+to+the+system%2C+including+forage.+%0D%0A%C3%AF%C2%82%C2%A7+The+production+index+was+closely+and+independently+associated+with+yield+and+calving+rate.+Culling+was+not+independently+associated+with+the+production+index+but+once+calving+rate+and+lactation+yield+are+taken+into+account%2C+culling+rate+also+becomes+a+significant+factor.%0D%0ACase+studies%0D%0A%C3%AF%C2%82%C2%A7+Case+studies+demonstrated+the+usefulness+of+recorded+data+analysis%2C+using+herd+management+software+and+observation+of+seasonally+adjusted+lactation+curves+to+examine+feeding+management.+In+all+five+herds%2C+apparent+and+reoccurring+seasonal+feeding+and+grazing+management+shortcomings+were+detected.%0D%0A%0D%0ARecommendations%0D%0A%C3%AF%C2%82%C2%A7+Further+research+would+need+to+be+carried+out+to+establish+financial+consequences+of+poor+fertility+in+organic+systems+with+different+milk+pricing+and+cow+values.+Similarly%2C+further+research+is+needed+to+establish+causes+for+high+numbers+of+services+per+conception+in+these+herds+and+to+establish+whether+this+phenomenon+exists+in+other+organically+managed+herds.%0D%0A%C3%AF%C2%82%C2%A7+The+herd+productivity+calculator+model+(LPEC)+showed+to+be+a+good+and+robust+measure+of+productivity.+Next+logical+step+in+this+analysis+would+be+to+gain+data+on+purchased+feeds%2C+so+that+the+productivity+index+can+be+expressed+in+terms+of+a+gross+margin+per+unit+of+forage+input.+This+would+allow+the+full+importance+of+forage+to+organic+dairy+systems+to+be+expressed%2C+and+would+also+allow+productivity+to+be+evaluated+in+terms+economic+margin+per+unit+of+input+produced+on-farm.+%0D%0A%C3%AF%C2%82%C2%A7+The+LPEC+generated+indices+could+also+be+utilised+to+examine+the+potential+impact+of+changes+to+systems+before+an+intervention+is+implemented%2C+by+including+costs+of+intervention+and+assumed+values+of+production+post-intervention.+Sensitivity+analyses+may+be+conducted+to+identify+the+relative+importance+of+individual+production+parameters+to+overall+herd+productivity.+%0D%0A%C3%AF%C2%82%C2%A7+Careful+assessment+of+lactation+characteristics+in+a+herd+is+needed+to+predict+the+overall+impact+of+extended+calving+intervals.+It+is+likely+that+in+most+organic+herds+feeding+management+would+need+to+be+adjusted+in+order+to+produce+lactations+with+low+late+lactation+decline+to+avoid+financial+losses+caused+by+longer+calving+intervals.%0D%0A%C3%AF%C2%82%C2%A7+Analysis+of+seasonally+adjusted+lactation+curves+as+a+monitoring+and+decision+support+system+for+feeding+management+is+likely+to+be+a+useful+for+organic+herds%2C+particularly+during+conversion+period+when+new+feeding+systems+need+to+be+introduced+in+a+herd.&rft.date=2001&rft.type=Report&rft.type=NonPeerReviewed&rft.format=application%2Fpdf&rft.identifier=http%3A%2F%2Forgprints.org%2F6609%2F1%2FOF0170_2152_FRP.pdf&rft.identifier=Hovi%2C+M+(2001)+Organic+dairy+cows%3A+milk+yield+and+lactation+characteristics+in+thirteen+established+herds+and+development+of+a+herd+simulation+model+for+organic+milk+production.&rft.relation=http%3A%2F%2Forgprints.org%2F6609%2F