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Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences, Kungsängen Research Centre, SE-753 23 Uppsala, Sweden
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Abstract |
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 Top Abstract INTRODUCTIONMILKING FREQUENCYTHE MILKING PROCESSMILK QUALITYCOW TRAFFICANIMAL WELFAREPROS AND CONSLITERATURE CITED |
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Key Words: animal welfare • automatic milking • cow traffic • milk quality • milking frequency
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INTRODUCTION |
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TopAbstractINTRODUCTIONMILKING FREQUENCYTHE MILKING PROCESSMILK QUALITYCOW TRAFFICANIMAL WELFAREPROS AND CONSLITERATURE CITED |
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). Today, about 8,000 AM units are in use on approximately 5,500 farms worldwide (O. Markusson, DeLaval, Tumba, Sweden; personal communication).
It soon became apparent that AM is much more than milking; it is an entirely new management system in which consideration must be given to milking, milk quality, feeding, cow traffic, cow behavior, grazing, and animal welfare, just to mention some aspects. Problems with poor milk quality and increased somatic cell count (SCC), were reported initially (Jepsen and Rasmussen, 2000; Klungel et al., 2000), but also the vast potential of AM management was highlighted, where success would depend on farm conditions and the herd manager’s management skill (Rossing et al., 1997; Lind et al., 2000; de Koning et al., 2002).
The AM system is now an established management system in Europe. The main markets for AM systems are found in countries with high-yielding cows, high milk prices, and high labor costs (Lind et al., 2000). Originally, AM was targeted for small family farms with 50 to 150 dairy cows. However, with continuous technological progress and increased management skills, AM nowadays is installed on larger farms with more than 500 cows per herd and this trend is increasing, although the largest market remains for 1 to 2 AM single stall units, (O. Markusson, DeLaval, Tumba, Sweden, personal communication).
Research on AM has identified the pros and cons of using the system. Herein, we discuss some of the pros and cons of AM, with focus on milking frequency, milk quality, cow traffic, and animal welfare.
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MILKING FREQUENCY |
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TopAbstractINTRODUCTIONMILKING FREQUENCYTHE MILKING PROCESSMILK QUALITYCOW TRAFFICANIMAL WELFAREPROS AND CONSLITERATURE CITED |
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). Furthermore, the cows can be milked at frequencies predetermined by the herd manager, whereby milking frequency can be adapted to stage of lactation or management system.
Milking frequencies of more than twice daily are desired in high-yielding cows because 3 milkings daily are expected to enhance lactation milk yield by 10 to 15% on average (Klei et al., 1997; Österman and Bertilsson, 2003). When AM and twice-daily parlor milking were compared within the same herd, the average milking frequency under AM rose to almost 2.5 milkings per day. Milk production increased from 2% (Wagner-Storch and Palmer, 2003) up to 7% (Svennersten-Sjaunja et al., 2000) and 8% for multiparous cows (Speroni et al., 2006). Data from the National Dutch data file further supports the expectation of an increased milk yield after introduction of AM (Kruip et al., 2002). Average daily milk yield was greater for cows milked with AM compared with twice-daily conventional milking (CM), but was not as great as for those herds where thrice-daily CM was practiced.
With AM it is possible to control milking frequency at different stages of lactation. Increased milking frequency during early lactation increased total milk production significantly (Svennersten-Sjaunja and Pettersson, 2005). Data were collected in an AM system with primiparous and multiparous cows. In the analyses, parity groups were divided into 4 groups depending on milking frequency (Table 1). Cows milked more frequently throughout lactation produced greater quantities of milk compared with the other groups irrespective of parity. Noteworthy was that a low milking frequency during early lactation could not be fully compensated by increased frequency after peak lactation. This probably was due to the fact that increased milking frequency during early lactation influences the cellular dynamics within the mammary gland. Increased milking frequency during early lactation increased cell proliferation (Hale et al., 2003), and apoptosis seems to be sensitive to number of milkings per day (Stefanon et al., 2002).
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), and this must be considered in the management routines. Further, it was reported that the milking interval is related to the individual cow (de Koning and Ouweltjes, 2000), and the effect of milking interval on milk yield is dependent on the level of milk yield (Hogeveen et al., 2001). Thus, the manager must control the length of milking intervals during lactation.
Some commercial farms have reported that the expected increase in milk yield failed to appear after installation of AM. The lack of increase in milk production could partly be due to a reduction in lactation length (Billon and Tournaire, 2002). Irregular intervals between milkings and failure of teat cup attachment could be other reasons for failure of AM to increase milk yield (Bach and Busto, 2005). Long intervals between milking have been reported to decrease mammary blood flow (Delamaire and Guinard-Flament, 2006a), and downregulate the udder’s ability to extract nutrients from the blood (Delamaire and Guinard-Flament, 2006b), 2 factors that greatly influence milk synthesis.
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THE MILKING PROCESS |
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TopAbstractINTRODUCTIONMILKING FREQUENCYTHE MILKING PROCESSMILK QUALITYCOW TRAFFICANIMAL WELFAREPROS AND CONSLITERATURE CITED |
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). It is assumed that stressed cows have disturbed milk ejection from the alveolar compartments and mainly cisternal milk is recovered (for review, see Bruckmaier and Blum, 1998). This negatively affects milk production and lactational persistency. This assumption is strengthened by the observation that the presence of people that handled cows roughly during milking caused a 70% increase in the cows’ residual milk (Rushen et al., 1999). In a working AM system, the animals are treated in the same way at each milking and the routines are predictable for the cows. Consistent milking routines have been reported to significantly increase milk production (Rasmussen et al., 1990).
A successful milking event requires that both cisternal and alveolar milk are obtained. The milk stored in the alveolar compartments is only available if milk ejection occurs (Bruckmaier and Blum, 1998). To completely evoke milk ejection, oxytocin must be released from the pituitary gland and be transported to the udder where it acts on the myoepithelial cells to promote contraction. Tactile stimulation of the teats activates the milk ejection reflex. When AM was introduced, concern was raised about the efficiency of tactile teat stimulation during the teat cleaning process, and about the sequential attachment of the teat cups. It was demonstrated that the stimulation performed during teat cleaning resulted in sufficient oxytocin release for milk ejection (Dzidic et al., 2004), as did the sequential teat cup attachment (Bruckmaier et al., 2001). Stripping yielded similar amounts of milk in cows milked with AM and CM, further indicating that stimulation of milk ejection is sufficient with AM relative to CM (Svennersten-Sjaunja et al., 2000). However, when udder fill is low, such as during late lactation or after short milking intervals, the interval from start of teat stimulation until the onset of milk ejection is greater compared with when udder fill is high (Bruckmaier and Hilger, 2001), an observation that needs to be considered with AM.
In an AM system, cows are usually fed concentrate during milking. This routine has been reported to reduce milking time and increase milk flow and udder emptying (Samuelsson et al., 1993). The probable explanation for this is improved oxytocin release during milking when concentrates are fed (Svennersten et al., 1995). In addition, feeding concentrates in the milking unit (MU) increases the cows’ motivation to visit the MU (Prescott et al., 1998), which is of vital importance for AM systems because the cows have low motivation for being milked.
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MILK QUALITY |
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TopAbstractINTRODUCTIONMILKING FREQUENCYTHE MILKING PROCESSMILK QUALITYCOW TRAFFICANIMAL WELFAREPROS AND CONSLITERATURE CITED |
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; Rasmussen et al., 2002). Such effects have significant negative consequences for the farmer and for the dairy industry. Therefore, several research projects were initiated to understand and solve the problem with deteriorated milk quality on farms with AM. Milk Fat Quality
A comparison of CM and AM in a long-term study showed no differences between the milking systems for gross composition, such as fat and protein contents (Svennersten-Sjaunja et al., 2000). However, in milk collected from farms that had introduced AM, the levels of milk FFA were increased compared with farms using CM (Justesen and Rasmussen, 2000) or when compared with levels of milk FFA before AM was introduced (Klungel et al., 2000; de Koning et al., 2003). Elevated FFA content is undesirable in milk because it causes rancid flavors in dairy products (Tuckey and Stadhouders, 1967) and decreases the ability to convert milk into processed dairy products (Sapru et al., 1997).
It is not yet fully understood why the content of milk FFA increased when cows were milked with AM. Increased levels of milk FFA have been reported as a result of increased milking frequency (Ipema and Schuiling, 1992; Klei et al., 1997) or short milking intervals (Ahrné and Björk, 1985). The typically greater than twice daily milking frequency or the irregular milking intervals in dairy herds where AM is practiced can partly explain this phenomenon. Moreover, it has been observed that the duration of the milking interval was important because FFA increased after short intervals (i.e., 4 or 6 h) irrespective of the duration of the preceding milking interval (i.e., if the short milking interval was preceded with an 8 or 12 h milking interval; Wiktorsson et al., 2000).
Membrane material covering the fat globules is important for protecting milk fat globule from lipolysis. The activity of various enzymes present in the milk fat globule membrane can indicate whether there is enough membrane material to cover newly formed fat globules and restrict lipolysis. One enzyme present in the milk fat globule membrane is 
-glutamyl transpeptidase (Baumrucker, 1979). The activity of this enzyme has been used as a marker when testing whether lack of membrane material could be the reason for increased milk FFA when cows are milked more frequently. In a recent study, no indications were found that supported the hypothesis that lack of membrane caused elevated FFA when milking more than twice daily (Wiking et al., 2006).
Another reason for the increased FFA content could be the fat globule size (Wiking et al., 2006). Four milkings daily resulted in much higher levels of FFA compared with twice-daily milking. The increase was only detected in milk after storage at 4°C for 24 h, indicating a weakness in the fat globule membrane; however, that increased milking frequency resulted in milk fat globules with larger average diameters was noteworthy (Wiking et al., 2006). This observation agrees with others who have reported a tendency toward larger fat globules with shorter milking intervals, although results were not always statistically significant (Svennersten-Sjaunja et al., 2004; Abeni et al., 2005). Larger fat globules have been observed to be more susceptible to lipolysis than smaller ones (Wiking et al., 2003). When the milk was exposed to mechanical stress by pumping, milk with the largest fat globules also had the highest FFA levels (Wiking et al., 2003), indicating that the membrane covering the larger fat globules was less stable.
Increased FFA content in milk is a drawback for AM system; however, Hamann et al. (2004) concluded that the levels of FFA in milk collected after extreme milking intervals were in the same range as for conventional bucket milking systems because milking intervals of <6 h and >12 h resulted in FFA levels of 0.31 and 0.24 mmol/L, respectively, with an average value of 0.28 mmol/L. However, corrections were not made for fat content, which also varied due to milking interval. The FFA content in bulk milk has been studied further in Denmark. Rasmussen et al. (2006) reported that the acidity in the AM milk was higher compared with milk from conventionally milked herds. The problem could be an artifact of technical origin because the main faults causing high acidity in milk from AM farms could be explained by stirring of the milk in the milk tank (79%), pumping of the milk (67%), and chilling the milk (58%). If this is so, the problem with increased FFA is a question for further investigation. However, they also found that milk yield per milking was an important factor to consider for reduction of FFA in the milk because the shorter milking intervals result in lower milk yields per milking (Rasmussen et al., 2006).
Milk Hygiene
Reports from the Netherlands and Denmark indicated that TBC increased in the bulk milk after introduction of AM (Klungel et al., 2000; Rasmussen et al., 2002). It was suggested that the bacteria could originate from the teat skin or be due to insufficient cleaning of the MU and inadequate cooling of the milk (Rasmussen et al., 2002). Nevertheless, it was reported that after 6 mo, the TBC stabilized and after an additional 6 mo, the level of TBC was almost the same as on farms with CM (Van der Vorst et al., 2002), indicating that the farmers and manufacturers became aware of the origin of the problem.
Early studies reported that cleaning the teats with horizontal rotating brushes or cleaning in the same teat cup was better than no cleaning but was not as good as manual cleaning in CM (Schuiling, 1992). Hovinen et al. (2005) visually examined the results of teat cleaning in different AM teat cleaning systems and found that cleaning teats in a teat cup was more efficient than brushing. When different AM manufacturers’ brands were compared for the teat cleaning efficiency, great variations were observed (Knappstein et al., 2004). Further, the initial bacterial contamination of teats before cleaning was significant for cleaning efficiency of teats (Knappstein et al., 2004). It was also observed that the highest coliform counts in bulk milk was on farms with low teat cleaning efficiency, indicating that it was partly a farm management problem.
The teat cup cleaning efficiency was tested further in a study where the teats were dipped in a solution with sterilized manure water with Clostridium tyrobacterium spores 20 min before milking. Prior teat cup attachment, the teats were left uncleaned, cleaned manually, or cleaned in an AM teat cup. Conventional manual cleaning removed 65% of the bacterial spores whereas AM cleaning removed 98% (Melin et al., 2004). Therefore, the AM teat cleaning per se was not the major problem. Several factors contributed to the contamination routes of bacterial spores in a barn, such as contaminated feed, bedding material in the cubicles, and use of mechanical scrapers (Magnusson, 2007). To overcome the problem, hygiene management must to be improved, not only focusing on teat cleaning but also maintaining high hygienic standards in cubicles and alley floors.
Milk Somatic Cell Count
Concern was raised about the AM system regarding udder health and milk SCC when it was observed that bulk SCC increased after introduction of AM (Klungel et al., 2000; Rasmussen et al., 2001, 2002; Kruip et al., 2002). However, it was also shown that AM does not increase the incidence of intramammary infections and SCC or promote deterioration of teat tissue condition when cow health status and herd management are good from the beginning (Zecconi et al., 2003). In a later Danish study where SCC was followed for 1 yr after installation of AM, a slight increase in SCC was observed initially during the 3 first months, but later on no differences were found in the SCC when the year before installation was compared with the year after installation and no increase in clinical mastitis was detected (Bennedsgaard et al., 2006). Therefore, elevated SCC probably was due to factors other than the AM system per se.
It was observed that cows managed in the AM system leak milk between milkings more frequently than cows in a CM system (Persson Waller et al., 2003). Increased milk leakage is related to a higher risk for mastitis. Cow-related factors for increased milk leakage include high peak milk flow and teat canal protrusion (Klaas et al., 2005). Why cows leak milk more frequently between milking in AM systems is not fully understood. However, it has been proposed that milk leakage in cows might be due to large amount of cisternal milk creating a high udder pressure followed by milk leakage (Rovai et al., 2007) rather than a result of milk ejection evoked between milkings. Noteworthy is that Persson Waller et al. (2003) observed that 62% of the primiparous and 28% of the multiparous cows were leaking milk at least once during the study. Primiparous cows usually have smaller cisternal compartments compared with older cows (Pfeilsticker et al., 1996).
Technical stoppages of the MU in the AM system have been reported to increase milk SCC. When a stoppage occurs in a CM system, all cows can be milked in a rather short time, while in an AM system, only 1 cow at a time can be milked and some cows can experience extremely long intervals between milkings. After rather long stoppages of up to 4 h, the bulk milk SCC increased from 50,000 to 250,000 cells/mL. If the stoppage was repeated, the bacteria count was increased also (Pettersson et al., 2002). This indicates the importance of service and spare parts being available within a short time to minimize downtime of AM systems.
Data from commercial farms further indicated that SCC in bulk milk was markedly higher in herds where the cows had a high variation in milking interval, a standard deviation >3 h. The importance of arranging for milking intervals to be within 12-h margins was also stressed because data from commercial farms revealed that farms on which most of the cows were milked within 12-h intervals also had a lower SCC bulk (G. Pettersson, unpublished results).
However, it has also been reported that AM does not increase SCC. In a 25-wk-long study in which the milk SCC was compared in CM and AM in animals from the same herd, milk SCC in quarter strip milk were significantly lower in AM cows compared with cows in a CM system (Berglund et al., 2002). This observation was further confirmed by Hamann and Reinecke (2002). In AM, the teats cups are detached from the individual teat as soon as the milk flow reaches the predetermined level for detachment (referred to as quarter milking), thereby reducing the overmilking of teats. Overmilking has negative effects on teat end quality, such as hardness and discoloration (Hillerton et al., 2002). Berglund et al. (2002) also found that AM seemed to be gentler to the teats compared with CM.
An AM system consists of one stationary milking unit that can be provided with different types of sensors for milk quality control, including sensors for detection of mastitis. Measurement of milk yield and milk composition (Linzell and Peaker, 1972) and electrical conductivity (Linzell and Peaker, 1975) also can be used as chemical sensors (Mottram et al., 2007). It can be questioned if electrical conductivity alone could be a sufficient tool for detection of udder health problems because several other factors in milk, such as fat globule size and air bubbles, interfere with the measurements. A detection model for mastitis has been described where both electrical conductivity and milk yield on a quarter level basis is considered in time-series models (de Mol and Ouweltjes, 2001). Possibilities for detection of abnormal milk for separation have been discussed (Rasmussen, 2004). Deviations in some of the milk components, such as lactose, lactate, and N-acetyl-β-D-glucosaminidase have been proposed for detection of udder health disturbances (Hamann et al., 2004). Lactose decreased markedly in udder quarters where SCC increased (Berglund et al., 2007). Lactose is of special interest for detection of udder disturbances because it is a stable milk component with a low relative day-to-day variation and has an osmotic regulatory property. Recently, on-line somatic cell counter for use in AM systems were introduced to the market. The measurement principle has been evaluated. It was shown that repeatability (0.99) and recovery rate (99.3%) were sufficient for identifying the SCC in milk samples (Sarikaya and Bruckmaier, 2006). An index of measurements including milk yield, milk components, and SCC should give the most reliable indication of udder health because short lasting increases of milk SCC can be due to other reasons than bacteria infection like effect of physical stress (Yagi et al., 2004).
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COW TRAFFIC |
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TopAbstractINTRODUCTIONMILKING FREQUENCYTHE MILKING PROCESSMILK QUALITYCOW TRAFFICANIMAL WELFAREPROS AND CONSLITERATURE CITED |
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; Olofsson, 2000; Harms, 2004; Melin, 2005; Oostra 2005; Wredle, 2005). Cows housed in a free stall barn with voluntary visits to feeding and milking areas develop individual patterns of eating and diurnal activity over time. This presents a great potential for control and decision making in individual management systems (Stefanowska et al., 1999b, Melin et al., 2005).
Free, semiforced, and forced cow traffic systems have been tested in full-scale experiments by Forsberg et al. (2002) and Harms (2004). These authors observed that free traffic resulted in the lowest milking frequency compared with forced or semiforced traffic systems. The free traffic system also had the highest frequency of cows needed to be fetched for milking due to long milking intervals. On the other hand, the number of meals was much higher with free traffic, but the feed consumption was almost the same. It was noteworthy that there were only 4 or fewer meals per cow each day in the forced traffic system. Milk yield did not differ much but tended to be higher during free traffic. Harms (2004) reported that, in all traffic systems, repeated lack of feed at a certain period of the day (e.g., late evening) resulted in a decrease in number of milkings during the same period. An explanation for why cows in free traffic tended to have higher milk yield might be that more frequent meals results in a more effective utilization of the feed, indicating that when milking frequency is influenced by the cow traffic system, even the feeding management must be considered.
The traffic system influences the behavior of the cows beyond the number of feeding and milking visits. Ketelaar-de Lauwere et al. (1998) found that cows in forced traffic spent more time standing in the feeding area than cows in the free traffic. In the experiments by Forsberg et al. (2002), the effect of increased restrictions in the traffic systems due to use of controlling gates was especially negative for the low-ranked cows because they spent more time in the milking queue compared with high-ranked cows. Queuing in front of the MU increased and resting time in the cubicles decreased when the traffic system changed from free to semiforced and forced. Hermans et al. (2003) found that cows in semiforced traffic spent more time in the feeding area, less time standing in the free-stalls, and visits to the MU were more evenly distributed among these cows than those in the forced traffic system. The placement of the selection gate is also important in the semiforced traffic system. Stefanowska et al. (1999a) concluded that a passage with walk-through selection should be located so cows can pass the selection in a straight line between the lying and the feeding areas.
Studies have shown that AM and traditional grazing can be combined. In CM systems, the herd manager brings the cows in twice daily for milking, whereas in a herd with AM, the cows are presumed to visit the MU voluntarily. It is quite possible to reach a milking frequency of 2 or more milkings daily when AM is combined with grazing (Ketelaar et al., 2000; Spörndly and Wredle, 2004). However, it has been reported that the distance to pasture seems to influence the number of visits to the MU (Spörndly and Wredle, 2004).
Different methods to optimize milking frequency in AM systems during grazing have been experimentally evaluated. Supplemental feeding of silage indoors did not improve milking frequency or milk yield (Spörndly and Wredle, 2004). The availability of the drinking water has also been used to improve the milking frequency in AM systems. However, no effects were seen on milking frequency or milk yield between cows offered drinking water both in the barn and on pasture compared with drinking water only in the barn (Spörndly and Wredle, 2005). The use of an acoustic signal to increase the motivation of cows to visit the MU has been tested. The cows were trained using operant conditioning and, from the results, it was concluded that cows could be trained to approach a MU following an acoustic signal (Wredle et al., 2004), though cows on pasture displayed a low response compared with when they were kept indoors (Wredle et al., 2006). Based on the studies performed so far, it can be concluded that grazing can be used with AM as long as the distance from MU to pasture is relatively short.
New cows, mostly heifers, will continuously be introduced into an AM herd. Upon arrival, cows must find their social rank in the herd, and in forced cow traffic systems, become accustomed to controlling gates in different forms and in all cow traffic systems, to the MU. Hamilton (2007) studied the effect of introduction of heifers prior to calving in an AM barn with semi-forced cow traffic. In total, 109 heifers were studied, of which 66 heifers had been in the barn for at least 7 d before calving and the others were introduced after calving. During the first 10 wk after calving, the trained group had shorter milking and feeding intervals, which means that they visited the milking unit and feeding area more frequently and the duration of visit was shorter. From wk 11 to 20, there were no differences between the groups in these variables. Probably due to the increase in number of feeding visits and milkings during early lactation, the daily milk yield was 1.5 kg greater in the trained group during the entire study.
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ANIMAL WELFARE |
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TopAbstractINTRODUCTIONMILKING FREQUENCYTHE MILKING PROCESSMILK QUALITYCOW TRAFFICANIMAL WELFAREPROS AND CONSLITERATURE CITED |
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Hagen et al. (2005) observed that the cows kept in an AM system displayed an increased chronic stress, measured as heart rate variability, compared with cows kept in a loose housing system. Elevated levels of cortisol can be used to indicate stress in animals. However, stress, as determined heart rate measurements, was not observed during milking (Hagen et al., 2005), which agrees with Gygax et al. (2006) who could not find any differences in milk cortisol between cows milked in an AM vs. a CM system. Hopster et al. (2002) also did not find any significant differences in behavioral or physiological responses of cows during milking in an AM vs. a CM system.
Weiss et al. (2004) evaluated the effect of the conversion from conventional parlor milking to AM on physiological responses of cows. Most cows adapted to the new system within days, but there was wide individual variation among cows. During the first visit to the MU in an AM system, the heart rate was noticeably greater than during parlor milking but during the second visit to the MU, the heart rate was similar to that during milking in the CM parlor. The cows’ adaptability to AM seemed to be related to the individual sensitivity of their adrenal cortex to ACTH. In AM systems, there is a risk for failure of milking, such as missed attachment of the milking cluster. How failed milking influences cow behavior was experimentally tested by Stefanowska et al., 2000. They found that an missed milking negatively influenced cow behavior, such as less time spent lying and more frequent urinating (Stefanowska et al., 2000).
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PROS AND CONS |
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TopAbstractINTRODUCTIONMILKING FREQUENCYTHE MILKING PROCESSMILK QUALITYCOW TRAFFICANIMAL WELFAREPROS AND CONSLITERATURE CITED |
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A key factor in AM is well-functioning cow traffic for all cows, which can be achieved when feed is always available. This demands investment in feeding equipment, such as automatic feed wagons or feeding troughs. Lack of feed during parts of the day will increase the synchronized behavior among cows, resulting in queuing problems in front of the MU, lower milking frequency, increased variations in milking intervals, and increased labor costs for fetching cows for milking.
Relative to CM management, the milking process in AM is consistent and the milking routines are predictable for the cows, which is a prerequisite for successful milking. Crucial parts of the milking process are teat localization and teat cup attachment. These processes can be disturbed by a malfunctioning robotic arm, misplaced teats or abnormal udder shape, dirty teats, or a restless cow leading to an incomplete milking of one or more quarters. A high frequency of milkings that end abnormally may increase udder health problems and reduce milk quality.
Increased FFA content in milk from AM has been reported in several studies, as discussed previously. Although the increase compared with CM is relatively small, it is a potential problem because the increased FFA content appears in stored milk. The final solution to the problem remains to be found.
In AM, many cows are milked in the same milking stall provided with 1 milking unit. In this stall, technical equipment, including sensors, can be installed to give unique opportunities for management decisions and production and health control of the individual cow.
Maintenance requirements for AM systems are higher compared with CM systems because of the level of technology is higher and relies on a more skilled operator for daily maintenance. A highly skilled technician must also be available on short notice (within a few hours) and with a ready supply of spare parts to avoid extended periods of inactivity in the AM unit. Even the herd manager must be able to visit the AM barn any time of the day to fix stoppages in the MU and alarms from the AM.
From the literature, it can be concluded that successful AM depends on farm conditions and the knowledge and management skills of the herd manager. Finally, humans can never be replaced with technical equipment; herd managers must supervise and manage the system.
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Footnotes |
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2 Corresponding author: Kerstin.svennersten{at}huv.slu.se
Received for publication August 16, 2007. Accepted for publication November 5, 2007.
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LITERATURE CITED |
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TopAbstractINTRODUCTIONMILKING FREQUENCYTHE MILKING PROCESSMILK QUALITYCOW TRAFFICANIMAL WELFAREPROS AND CONSLITERATURE CITED |
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uhová, and R. M. Bruckmaier. 2004. Effects of cleaning duration and water temperature on oxytocin release and milk removal in an automatic milking system. J. Dairy Sci. 87:4163–4169.This article has been cited by other articles:
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  A. Bach, M. Devant, C. Igleasias, and A. Ferrer Forced traffic in automatic milking systems effectively reduces the need to get cows, but alters eating behavior and does not improve milk yield of dairy cattle J Dairy Sci, March 1, 2009; 92(3): 1272 - 1280. [Abstract] [Full Text] [PDF]
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F. Abeni, M. G. Terzano, M. Speroni, L. Migliorati, M. Capelletti, F. Calza, L. Bianchi, and G. Pirlo Evaluation of Milk Enzymes and Electrolytes, Plasma Metabolites, and Oxidative Status in Twin Cows Milked in an Automatic Milking System or Twice Daily in a Conventional Milking Parlor J Dairy Sci, September 1, 2008; 91(9): 3372 - 3384. [Abstract] [Full Text] [PDF]
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 G. E. Dahl The Eighth International Workshop on the Biology of Lactation in Farm Animals: Introduction J Anim Sci, March 1, 2008; 86(13_suppl): 1 - 2. [Full Text] [PDF]
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