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Beck, Julia, 2014. Free cow traffic in automatic milking systems (AMS) : a case study on nine commercial dairy farms in Sweden. Second cycle, A2E. Uppsala: SLU, Dept. of Animal Nutrition and Management

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Abstract

In Automatic Milking Systems (AMS), cows are kept in a free stall barn equipped with one or several milking units (MU). The cows’ activities in the system are called cow traffic. There are three types of cow traffic systems: guided, partly-guided and free. Free systems have no gates, allowing the cows access to the feeding and resting areas at any time. This study pre-sents the results of on-farm research on such free systems, especially with a view to produc-tion results, feeding and management routines, animal health, and housing. The underlying field work was undertaken on nine commercial dairy farms in Sweden and comprised of man-ager (farmer) interviews, own observations at the target-barns, and the acquisition of standard data that were collected and stored by the farms’ AMS software programmes. The data, cov-ering the system responses and interactions of 837 lactating cows in 15 MUs over a period of 30 days were subsequently processed by aid of the statistical pc-programme SAS and Micro-soft Excel.
With each of the 15 investigated MUs shared by 40 to 65 cows, the milking frequency varied from 2.50 to 2.84 milkings per cow and day at intervals between 8.4 and 9.6 hours. While there was no relationship between milking frequency and annual milk yield or herd size, the latter clearly affected milking intervals in a positive fashion. The number of non-milking (ex-tra) visits to the MUs varied between 0.71 and 1.51 per day. When cows paid up to two extra visits and five visits in total to the MUs, milkings took place at shorter intervals and were more evenly distributed over the day. However, no additional positive development in milk-ing interval could be seen for more than two extra visits. There was a tendency for a signifi-cant negative correlation (p<0.09) between the number of extra visits per cow and her annual milk yield. There also was a significant negative correlation (p<0.001) between the number of extra visits per cow and her daily milk yield. The share of unsuccessful milkings varied widely, ranging from 1.94 to 12.19 % of all milkings (median 3.17 %). If there were specific times for fetching cows that were late for milking, cows with unsuccessful milkings were also fetched, even though the farmers were not aware of this.
The feeding patterns applied on the participating farms were distinctly different from each other and ranged from 2 to 16 times per day. Whereas all nine farmers stated that the cows were fed roughage ad lib, only two actually had feed on the feeding table at all times. On four of the farms, the feeding table was empty every morning. In consequence milking activities were highest after morning feeding and low prior to feeding. Only 56 % of the farmers had an idea how much milk they were feeding for at the feeding table. There was a significant nega-tive correlation (p<0.023) between the maximum allowance of concentrate per cow and day in the MU and the annual milk yield per cow. There was a tendency for a positive correlation (p<0.093) between the maximum concentrate allowance in the MU and the number of extra visits, however without affecting the number of daily milkings.
The fetching frequencies were quite low, compared to what has been observed in research studies. Free time in the MU had a large effect on the number of involuntary milkings (fetch-ings). For free time over 11 %, there were 2.1 % involuntary milkings, but for free time less than 11 % there were 5.0 % involuntary milkings. There was a significant positive correlation (p<0.036) between the proportion of involuntary milkings and herd size. The average fetching frequency for the farms with less than 55 cows per MU was 2.3 % (1.0 – 3.8 %) and for the farms with more than 60 cows it was 7.1 % (6.1 – 8.0 %). The average minimum interval for fetching was 13 hours, with variations from 10 to 20 hours. There was a negative correlation (not significant) between the fetching frequency and the minimum interval for fetching. When there were no specific times for fetching, the milking interval was more regular during the day, but somewhat longer than on farms with specific fetching routines.
Cleaning of the MU had a strong effect on the number of milkings per hour, and there was a drop in milkings already some time before the actual cleaning. Usually there was a peak in milkings after cleaning. However, if the feeding table was empty prior to cleaning and feeding occurred shortly after cleaning, the peak was levelled off. There were considerable differences in the average milk flow rate, varying from 2.01 to 2.56 kg milk/minute (mean = 2.21). It turned out that herd size in terms of cows/MU was significantly positive correlated to the av-erage milk flow rate in the herd (p<0.013).
There were great differences regarding the average bulk milk somatic cell count (BMCC). It varied between 140 000 and 275 000 cells/ml (average 206 000). There was no pattern ob-served, when studying health problems on the investigated farms. Investments in AMS were primarily motivated by the need to provide for more flexibility in daily farm management. Other reasons were the reduction of heavy work related to conventional milking and to be less dependent of extern employees. A technical interest was also mentioned for motivation. Alarms and on-call duty were not a problem for any of the interviewed farmers.

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I automatiska mjölkningssystem (AMS) hålls korna i ett lösdriftsstall, utrustad med en eller flera mjölkstationer (MS). Kornas aktiviteter i systemet kallas kotrafik. Det finns tre system för kotrafik: styrd, styrd med förselektering och fri. I fri kotrafik finns inga grindar och korna kan röra sig helt fritt mellan foder- och liggavdelningen när som helst på dygnet. Syftet med den här studien var att undersöka fri kotrafik med avseende på produktionsresultat, utfodrings- och skötselrutiner, djurhälsa och inhysning. Studien omfattade nio kommersiella mjölkgårdar i Sverige. Den bestod av intervjuer med lantbrukarna, observationer i AMS-stallen, samt nedladdning av data från gårdarnas managementprogram. De insamlade uppgifterna innehöll information om interaktioner för totalt 837 mjölkande kor i 15 MS under en 30-dagars period, behandlades sedan i statistikprogrammet SAS och Microsoft Excel.
Var och en av de undersökta mjölkstationerna delades av mellan 40 och 65 kor och mjölkningsfrekvensen låg på 2,50 till 2,84 mjölkningar per ko och dag, samtidigt som mjölkningsintervallet varierade mellan 8,4 och 9,6 timmar. Det fanns inget samband mellan mjölkningsfrekvens och årsavkastning eller gruppstorlek (antal kor per MS), men den senare hade en gynnsam effekt på mjölkningsintervallet (större grupper hade ett kortare intervall). Även antalet avvisningar (extra besök) per ko och dag, som varierade mellan 0,71 och 1,51, hade en positiv effekt på mjölkningsintervallet. Upp till omkring två avvisningar och fem totala besök till MS per ko och dag blev mjölkningsintervallen kortare och jämnare, men vid fler avvisningar kunde ingen ytterligare positiv förändring i mjölkningsintervallet påvisas. Det fanns en tendens till en signifikant negativ korrelation (p<0,09) mellan antalet avvisningar och årsavkastningen per ko. Det fanns en signifikant negativ korrelation (p<0,001) mellan antalet avvisningar och dygnsavkastningen per ko. Variationen i andelen misslyckade mjölkningar var stor: 1,94 till 12,19 % av alla mjölkningar (median 3,17). Där specifika tider för hämtning av kor med långa mjölkningsintervall tillämpades hämtades också kor med misslyckade mjölkningar, även om ägaren inte var medveten om detta.
Det fanns stora skillnader i antalet utfodringar mellan de undersökta gårdarna, från 2 till 16 gånger per dygn. Alla nio lantbrukare påstod att de utfodrade grovfoder ad lib, men endast två bekräftade att det alltid fanns foder på foderbordet dygnet runt. På fyra av gårdarna var foderbordet tomt varje morgon vilket resulterade i låg mjölkningsaktivitet innan morgonutfodringen och hög aktivitet efteråt. Endast 56 % av lantbrukarna visste hur mycket mjölk de utfodrade för vid foderbordet. Det fanns en signifikant negativ korrelation (p<0,023) mellan maxgivan kraftfoder i MS per ko och dag och årsavkastningen per ko. Det fanns en tendens till positiv korrelation (p<0,093) mellan maxgivan i MS och antalet avvisningar, men antalet mjölkningar per ko och dag påverkades inte av kraftfodergivan i MS.
Hämtningsfrekvenserna var relativt låga jämförd med vad som visats i försök. Andelen fri tid i MS hade stor effekt på andelen ofrivilliga mjölkningar (hämtningar). Då det fanns över 11 % fri tid i MS var andelen ofrivilliga mjölkningar endast 2,1 %, men då den fria tiden var lägre än 11 % var andelen i stället 5,0 %. Det fanns en signifikant positiv korrelation (p<0,036) mellan andelen ofrivilliga mjölkningar och gruppstorleken. Den genomsnittliga hämtningsfrekvensen var 2,3 % (1,0 till 3,8 %) för gårdar med färre än 55 kor och 7,1 % (6,1 till 8,0 %) för gårdar med fler än 60 kor. Det minsta intervallet då kor hämtades till mjölkning var i genomsnitt 13 timmar, men varierade mellan 10 och 20 timmar. Det fanns en negativ korrelation (ej signifikant) mellan hämtningsfrekvensen och minimum intervallet för hämtning. När det inte fanns några specifika tider för hämtning var mjölkningsintervallet jämnt fördelat över dygnet, men något längre än på gårdar med specifika hämtningsrutiner.
Diskning av MS hade en stark effekt på mjölkningsfrekvensen och antalet mjölkningar per timme minskade redan en stund innan själva diskningen började. Normalt fanns en tydlig topp i antalet mjölkningar efter diskning, men om foderbordet var tomt innan diskning och utfodring skedde kort tid efter, fanns ingen sådan topp. Det fanns stora skillnader i den genomsnittliga mjölkflödeshastigheten på gårdarna, med variationer från 2,01 till 2,56 kg mjölk per minut (medel 2,21). Det fanns en signifikant positiv korrelation (p<0,013) mellan antalet kor per MS och det genomsnittliga mjölkflödet i besättningen.
Det fanns stora skillnader mellan de undersökta gårdarna med avseende på det genomsnittliga tankcelltalet. Det varierade mellan 140 000 och 275 000 celler per ml (medel 206 000).. Den främsta motivationen för att investera i AMS var den ökade flexibiliteten i det dagliga arbetet. Andra orsaker var att slippa det tunga mjölkningsarbetet i konventionell mjölkning och att bli mindre beroende av extern arbetskraft. Tekniskt intresse nämndes också som motivation. Larm och jourbehovet uppfattades inte som något problem bland de intervjuade lantbrukarna.

Main title:Free cow traffic in automatic milking systems (AMS)
Subtitle:a case study on nine commercial dairy farms in Sweden
Authors:Beck, Julia
Supervisor:Pettersson, Gunnar
Examiner:Bertilsson, Jan
Series:Examensarbete / Sveriges lantbruksuniversitet, Institutionen för husdjurens utfodring och vård
Volume/Sequential designation:466
Year of Publication:2014
Level and depth descriptor:Second cycle, A2E
Student's programme affiliation:1010A Agriculture Programme (admitted before July 1, 2007) 270 HEC
Department:(VH) > Dept. of Animal Nutrition and Management
Keywords:Cow traffic, Automatic milking systems, AMS
URN:NBN:urn:nbn:se:slu:epsilon-s-3095
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-s-3095
Subjects:Animal husbandry
Language:English
Deposited On:07 Mar 2014 10:58
Metadata Last Modified:07 Mar 2014 10:58

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