Are peaks and persistency different for cows in robotic milking?

Do cows in robotic milking systems get off to the same start in lactation and maintain the same persistency as those in other milking systems?

To answer that question, we consulted Lactanet’s database. The cows were divided into two groups, those in robotic milking systems and those in other milking systems with two milkings/day. Average daily milk yield per 10 days in milk was used for comparative purposes.

Number of milkings varies among robots

Robotic milking is the only system in which the number of milkings is variable. More frequent milking is encouraged at the start of lactation to stimulate the mammary gland and obtain higher peak yields. The number of milkings decreases gradually in mid- and late lactation. Does the variation in the number of milkings affect lactation curves? Separate graphs are shown below for primiparous and multiparous cows, with all production levels taken into account, for the year 2019.

A strong start

Primiparous cows

Initial production is slightly lower for first-lactation cows in robotic milking systems, but by 50 days in milk they surpass conventionally-milked cows and reach a higher peak yield. In both cases, production peaks at around 70 days in milk.

Graph 1. Average milk yield in relation to days in milk for primiparous cows in robotic milking systems versus their counterparts in other milking systems with two milkings per day.

graphique1_traite_robotisee

Table 1. Evolution of milk yield (kg/day) for primiparous and multiparous cows in robotic milking systems versus other systems with 2 milkings per day, for all levels of production.

 

Primiparous cows 

Multiparous cows 

Days in milk

Robot 

Other systems (2 milkings) 

Robot 

Other systems (2 milkings) 

10 

22.3 

25.7 

33.3 

35.9 

20 

27.1 

29.3 

40.1 

40.5 

30 

30.8 

31.9 

44.4 

43.5 

40 

32.6 

33.2 

46.1 

44.8 

50 

34.0 

33.8 

46.4 

45.1 

60 

34.1 

33.9 

46.0 

44.7 

70 

34.4 

33.9 

45.5 

44.1 

80 

34.3 

33.7 

44.7 

43.4 

90 

33.9 

33.5 

43.5 

42.7 

For primiparous cows, production from 10 days in milk to peak milk at 70 days in milk increases more rapidly in robotic milking systems. Average daily gains are as follows:

Robotic herds: 0.20 kg of milk/day in milk

Conventional herds: 0.14 kg of milk/day in milk

Multiparous cows

The lactation curve for multiparous cows is similar to that of first-lactation cows, with cows in robotic milking systems producing slightly lower yields than conventional herds at the start but surpassing them at 30 days in milk. In both cases, peak milk occurs at around 50 days in milk. But cows in robotic systems have consistently higher peaks.

Graph 2. Average milk yield in relation to days in milk for multiparous cows in robotic milking systems versus their counterparts in other milking systems with two milkings per day.

multiparous_cows

Production from 10 days in milk to peak milk at 50 days in milk increases more rapidly in robotic milking systems. Average daily gains are as follows:

Robotic herds: 0.33 kg of milk/day in milk

Conventional herds: 0.23 kg of milk/day in milk

Milk yields increase much more rapidly in robotic herds from the start of lactation to peak milk, 43% more rapidly in fact, and this applies as much to cows in their first lactation as to mature cows. This is undoubtedly part of the reason that research shows a risk of ketosis that is 1.45 times higher in robotic milking systems than in other types of milking systems.

Persistency, higher and lower

We looked at persistency in two different time periods: the period from 130 to 190 days in milk, and the period from 190 to 330 days in milk. Persistency was calculated on a 30-day rolling basis for each of these two periods. For the period from 190 to 330 days in milk, although the calculations were done for each 10-day stratum, the table includes only the results for 30-day strata to avoid overloading the table.

Primiparous cows

Table 2. Evolution of persistency for primiparous cows in robotic milking systems versus those in other systems with 2 milkings per day for the period from 130 to 190 days in milk.

 

Primiparous cows 

30-day persistency for primiparous cows (%)

Days in milk

Robot 

Other systems (2 milkings) 

Robot 

Other systems (2 milkings) 

130 

32.7 

32.2 

 

 

140 

32.4 

31.9 

 

 

150 

32.2 

31.6 

 

 

160 

32.0 

31.3 

97.8 

97.1 

170 

31.6 

31.0 

97.6 

97.3 

180 

31.4 

30.7 

97.4 

97.2 

190 

31.2 

30.4 

97.5 

97.2 

Average

 

 

97.6 

97.2 

Primiparous cows in robotic milking systems show slightly higher lactation persistency than those in other milking systems. The same is true in later lactation (more DIM). For cows in robotic milking systems, average persistency is of course lower toward the end of lactation (96.8% – Table 3) than in mid-lactation (97.6% – Table 2).

Table 3. Evolution of persistency in primiparous cows in robotic milking versus those in other systems with 2 milkings per day for the period from 210 to 330 days in milk.

 

Primiparous cows 

30-day persistency for primiparous cows (%)

Days in milk

Robot 

Other systems (2 milkings) 

Robot 

Other systems (2 milkings) 

210 

30.5

29.9 

97.2 

97.4 

240 

29.4 

28.9 

96.5 

96.6 

270 

28.2 

27.4 

95.8 

95.0 

300 

27.0 

26.3 

95.8 

95.9 

330 

26.8 

25.7 

99.1 

97.8 

Average

 

 

96.8 

96.5 

Multiparous cows

There are no major differences in persistency between robotic herds and herds in other systems for the period from 130 to 190 days in milk, although the average was slightly lower in robotic herds (94.2% versus 94.4%).

 Multiparous 30-day persistency for multiparous cows (%)
Days in milkRobot Other systems (2 milkings) Robot Other systems (2 milkings) 
130 40.1 39.6   
140 39.6 38.9   
150 38.7 38.2   
160 37.9 37.4 94.5 94.5 
170 37.2 36.7 93.9 94.6 
180 36.4 36.0 94.2 94.2 
190 35.7 35.3 94.2 94.4 
Average  94.2 94.4 
The findings were more or less the same for the period from 210 to 330 days, with robotic herds showing slightly lower persistency than the other herds (92.8% versus 93.0 %). Persistency is lowest at 270 days, and this result is consistent for all herds.
  Multiparous  30-day persistency for multiparous cows (%)
Days in milk Robot  Other systems (2 milkings)  Robot  Other systems (2 milkings) 
210  34.2  33.8  93.9  94.1 
240  31.8  31.5  93.0  92.9 
270  28.8  28.7  90.6  91.2 
300  26.6  26.7  92.3  93.1 
330  25.1  25.0  94.5  93.7 
Average     92.8  93.0 

Results seem to exceed expectations

The results differ somewhat from the generally-held perception of robotic herds. There are herds with much lower persistency at 200 DIM than the results shown here. Some robotic herds have a number of cows with a lactation persistency below 90% past 200 days in milk.

It is important to note that the number of milkings per cow decreases gradually over this period until dry-off. Some farms are more aggressive than others and demand a higher minimum milk yield per milking. The higher the target milk yield per milking, the more the number of milkings at the end of lactation is compromised, and persistency is likely to decline as well. This approach does keep more milk in the mammary gland, however, making it easier for the robot to attach the teat cups. In the case of a robot near maximum capacity, the decrease in the number of milkings at the end of lactation means that milking time can be redirected to cows in early lactation, which in turn allows fresh cows to milk more frequently and achieve higher peaks.

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By Gervais Bisson, agr.
A graduate in agronomy from Université Laval, Gervais has over 22 years of experience in dairy cattle feeding before joining our team. As an expert in dairy production - milking robots, he actively contributes as a consultant and author to the advancement of the dairy production industry.

This article has 2 responses

  1. Hello Gervais – thank you for the comparison with 2 times per day milking. This is interesting and a resource to refer to. I am curious to know what it looks like when you compare robotic milking in your data base to 3 times per day milking? Do you have a enough data to carry out this comparison?

  2. Hello Nancy, i will ask for a comparison with the herds on 3X milkings but the number of data can be an issue.

    What we know ; on a comparison dating back 4-5 years, we see that 3X herds have a slight decrease of 0.03 – 0.05% on the fat test like robots compare to 2x herds. In a more recent comparison, we see that 3X herds and milking robots have a urea rate of about 1 point higher than 2x herds.

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