Dr. Robert Tremblay
Automatic milking systems, often called robot milking, rely on cows coming to robot to be milked. It is understandable to expect that lame cows may be less likely to visit a robot. Lame cows might also make fewer visits to the feed bunk. Fewer visits to the feed bunk or to the robot might mean that you would expect lame cows to have lower milk production. Other research in Canada had already shown that there was a link between severe lameness, robot visits and milk production.
A research group at Guelph looked at data related to lameness, milk production and milk quality in 75 robot dairy herds in Ontario. They recently reported on the research trial in the Journal of Dairy Science.
They enrolled 75 farms in Ontario. The researchers visited each of the farms in 2019 to collect barn and management information and to score a minimum of 30 cows in each herd. The cows were scored for body condition on a scale where 1 meant underconditioned and 5 meant overconditioned. The cows were also scored for lameness on a scale from 1 to 5. Cows with a locomotion score of 3 or higher were considered clinically lame. Cows with a locomotion score of 4 or higher were considered severely lame. The researchers also collected milk production and milk quality data for the six months prior to their visit.
The farms had an average of 98 milking cows and 2.3 robots. Average production was 36 kg with an average of three visits to the robot per day. The average number of clinically lame cows was 28% with 3% of cows considered to be severely lame (locomotion score of 4 or more.)
There were fewer clinically lame cows on farms that used sand for bedding, that had more feed bunk space and that had fewer underconditioned cows. Cows were classified as underconditioned if they had a score of body condition score of 2.5 or less. Herds milking non-Holstein breeds were also more likely to have fewer clinically lame cows than herds milking Holsteins.
Herds with more severely lame cows (locomotion score of 4 or more) also had a greater proportion of cows that were under conditioned. Herds with higher curb heights also had more severely lame cows.
Herd average daily milk production increased as clinical lameness decreased. For each 10% decrease in lameness, milk production was higher by 2.0 kg/day/ cow. Those herds with fewer lame cows tended to have more feed push-ups each day too. Higher milk production was also associated with more visits to the robots.
Milk quality, as indicated by herd average SCC (somatic cell count), was impacted by several factors. Herds with lower clinical lameness and herds with a lower proportion of underconditioned cows, had lower SCC. Each 10% increase in clinical lameness was associated with an increase of 23,000 in average SCC. Doubling of the proportion of underconditioned cows from 5 to 10% was associated with an increase of almost 12,000 in average SCC. Herd average days in milk (DIM) also had an impact on SCC. Each increase of 10 DIM was associated with a 12,000 increase in SCC.
The use of sand bedding rather than organic bedding was associated with a lower herd average SCC. This has also been observed in other research on barns using conventional milking systems.
The research found no relationship between lameness score and average number of daily visits to the robots. More daily visits to the robot were seen in herds that had fewer cows on each robot and in herds that had more frequent alley cleaning. Cows in barns that used free traffic system had more visits to the robot than herds that used guided ow.
This research once again highlights the impact of lameness and body condition on milk production. Lameness and body condition impact both production and cow welfare.
Dr. Robert Tremblay is a veterinarian for Boehringer-Ingelheim and lives near Guelph.