Milk quality on Pennsylvania robot dairies: Part 3

Robotic dairies surveyed in Pennsylvania had good hygiene scores overall. Even so, those with cleaner cows had lower bacteria counts in bulk tank milk samples. 

In two previous articles I introduced a study conducted on 9 Pennsylvania dairy farms using robotic milking systems (Part 1) and discussed teat cleanliness and the technical success of the robotic milking systems to clean teats (Part 2). The current article will discuss cow hygiene on these 9 farms and begin to relate cow hygiene to management on the farms and milk quality of bulk tank milk samples. In an upcoming article I will go into more depth on milk quality on the farms. Full results of this study will be presented during a webinar April 28, 2015; for more information or to register for the webinar visit the Penn State Extension Technology Tuesday web page.

Hygiene scoring was conducted on two separate days during the study period with a minimum of 20 cows on each dairy scored on each day. The lower legs, udder, and upper legs of cows were scored from 1 (very clean) to 4 (very dirty) for hygiene. The percent of cows receiving scores of 3 (dirty) or 4 (very dirty) at each of the 9 farms are presented in Table 1. Lely recommends the percent of the herd receiving hygiene scores of 3 or 4 be less than 20% for the lower legs, less than 10% for the udder, and less than 15% for the upper legs. Using this guideline, most farms in the study were doing a good job at maintaining good hygiene. 

Table 1. Cow Hygiene Scores, % cows with score of 3 or 4.

Cow hygiene scores were assigned from 1 to 4, with one being very clean and 4 being very dirty. Percent of cows receiving scores of 3 or 4 are presented.
Farm ID Lower Leg Hygiene Udder Hygiene Upper Leg Hygiene
A 13.9 20.9 17.1
B 19.5 9.0 2.4
C 0.0 3.1 0.0
D 9.5 2.3 7.3
E 7.5 7.5 2.5
F 22.5 22.5 22.5
G 0.0 5.0 5.0
H 16.8 0.0 12.9
I 19.8 2.4 7.4
In the current study, lower hygiene scores (cleaner cows) were associated with lower standard plate counts and a lower occurrence of Staphylococcus aureus in bulk tank milk samples. 

Two of the farms in the study used deep bedded sand in their stalls. The rest of the farms used mattresses with a variety of bedding materials, including saw dust/wood shavings, composted manure solids, agricultural lime, and peanut hulls. On average, farms were understocked for the number of cows per stall, with 94 cows for every 100 stalls. Only 2 farms were over stocked for the number of stalls per cow, with each of these farms having 103 cows for every 100 stalls.

Seven farms in the study used automatic manure scrapers to clean lanes. Scrapers ran continuously throughout the day. The other 2 farms (Farms C and H) used a skid loader to remove manure twice a day; these farms also used deep bedded sand in the stalls. Farms cleaned stalls from 1 to 4 times per day, with most farms cleaning stalls twice a day. Farm C cleaned stalls 4 times per day. In the current study, more frequent stall cleaning was associated with lower preliminary incubation (PI) counts and a lower occurrence of Coagulase Negative Staphylococci (CNS) in bulk tank milk samples.

All farms singed udders to remove excess hair; this helps maintain cow hygiene and also improves efficiency of the robots during teat cleaning and attachment for milking. Udders were typically singed at freshening and again as needed throughout the lactation. Singeing was performed either in the robot or in headlocks. 

Even with the relatively small number of farms in the current study, we were able to identify differences in milk quality and relate them to some of the management practices on the farm. The use of sand bedding and more frequent cleaning of stalls were associated with better cow hygiene and improvements in milk quality. Even though farms using sand bedding had better cow hygiene than did cows using other bedding materials, most of these farms were able to achieve an acceptable level of cow hygiene. As with farms using conventional milking systems, the use of best management practices for maintaining cow hygiene are applicable to dairy farms using robotic milking systems. Some of these best management practices include more frequent scraping of manure in lanes and cleaning of stalls, along with ensuring adequate supply of clean and dry bedding material in stalls.


Mark your calendars for the 2015 Precision Dairy Expo!




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