MSU Extension Dairy

The return of an age-old practice is gaining popularity within the dairy farming community with the increasingly rapid adoption of automated milking systems (AMS) – feeding part of the ration concentrate during milking. AMS farms routinely feed concentrate at the milking robot to incentivize cows to voluntarily go to the milking robots. However, concerns and questions about the amount provided, nutritional composition, physical form and effects on overall feed efficiency, health and the economics of the system need to be addressed. 

In the AMS, the number of times cows visit the robot is defined by the management strategy and lactation phase. The most common way to reach the visits-per-day goal is by luring cows to the box with concentrate feeding. The amount fed to the cows is also predefined and can change from cow to cow, allowing an individualized nutritional plan to some extent. 

As AMS are a relatively new technology, research-based information on the best practices for concentrate feeding strategies for AMS herds is still limited. Nonetheless, given the rapid adoption of this technology, it is imperative that such recommendations are established to optimize AMS performance.

What do we know about feeding part of the concentrate separate from the diet?

The physical form of the concentrate

The current recommendation and most widely used concentrate form is pelleted feed. Reasons for this include:

• Palatability and cows' preference.
• Reduced waste and leftovers in the bowl.
• Ease of handling. 
• Higher intake per minute.

The downsides of using pellets include higher costs associated with the pellets and limited opportunity to use by-products and feeds produced on the farm. Producers are experimenting with alternatives to pellets, using simpler feed ingredients such as meals or farm-made processed grain mixtures. However, recent research from Canada observed that concentrate form (using steam-flaked barley to replace pelleted barley) affects milking behavior even when performance is not affected, suggesting that potential losses in performance can happen depending on the stage of lactation and traffic flow. The researchers conclude that using a pelleted concentrate in AMS is the best option to encourage voluntary visits to the AMS and reduce the time associated with nonproductive behavior.

How much concentrate? 

The main challenge when it comes to the milking frequency in AMS is that, beyond nutritional strategies, other factors also play a role, including the social structure of the herd, barn design, cow traffic, productivity and cow health. Maximizing the milking frequency of the right cows and minimizing the need for fetching cows are the main goals of using concentrate as a treat in the AMS box. On the other hand, opportunities exist to feed cows more precisely based on their needs, potentially increasing profitability. The best strategy will be farm-dependent, but we will discuss some of the benefits and downsides of each strategy below. 

The Canadian survey in 2013 reported an average of 9 lbs. of pellets offered in the milking robots daily. However, it can vary from 2 to 25 lbs. depending on the system (i.e., free-flow or guided flow). Swartz and colleagues (2022 – American Dairy Science Association presentation) reported an average of 12 lbs. of concentrate fed in the robots for 38 farms located in Minnesota and Wisconsin. The amount fed in the robots ultimately defines the nutritional density of the partial mixed ration (PMR). The variability of milk production and lactation stages in the same pen imposes a challenge, since greater amounts of concentrate are fed in the robots for high-producing cows in an attempt to avoid overfeeding cows that produce less milk. In addition, most AMS systems only have a single bin for storage and delivery of concentrate to cows in certain barns or pens. Under this situation, the only possibility to adjust cows' diets to their requirements is the amount of concentrate each cow is entitled to consume daily. Thus, cows receive different amounts of concentrate but with the same composition, which could result in an imbalanced nutrient supply as milk yield deviates from the yield the nutritionist used to formulate the feed supplement. 

Most studies report that increasing concentrate offered in the AMS also increases variability in concentrate intake. Especially when cows go voluntarily to the AMS, daily variations in milking frequency can occur. If the milking frequency decreases, the amount of concentrate the cow can consume in the AMS will also decrease – since there is a limited concentrate allowance delivered per minute during milking. Moreover, research shows a limit to a cow’s capacity to eat concentrate offered during milking. On average, cows are milked three times a day and spend around 6.8 minutes at the box; since cows can eat about 0.7 lbs. of pellets per minute, the maximum amount of pellets an average cow would be able to eat per day would be around 15 lbs.

Another less discussed point is that when feeding more concentrate in robots, nutritionists need to account for intake variability and substitution effect. Substitution refers to the decrease in PMR consumption when more concentrate is fed. The literature shows that the substitution effect is not linear and differs depending on the farm, diet and animals. The variation in the intake of PMR or concentrate can negatively impact milk production, as reported by other studies evaluating variation in milk production due to the daily variation in diet nutritional composition and intake. 

Moreover, studies that showed an increase in milk production due to increased amounts of pellets fed in the robot, like the recent studies published by Schwanke and colleagues in 2019 and 2022 (3.3 lbs. and 3.5 lbs. of milk per cow daily, respectively), often observed consistent PMR intake and greater dry matter intake (DMI), which partly explain the response in milk production. In contrast, if you feed a concentrate with higher substitution rates, the cow will reduce her PMR intake to a greater extent, reducing the total DMI and likely not improving milk yield.

Reducing the amount of concentrate fed in the robot and maximizing nutrient intake from PMR can be a good economic strategy when feeding a more homogenous group of cows and/or when concentrate costs are high. Halachmi and colleagues (2005) compared milking frequency when limiting concentrate delivery at each milking to 2.64 lbs. versus a maximum allowance of 15.4 lbs. per day. They reported no differences in the number of voluntary visits to the AMS. Similarly, Bach and colleagues (2007) compared a concentrate allowance of 6.6 or 17.6 lbs. per day and reported no differences in the number of daily visits to the AMS. Producers may have more flexibility to use other feed forms without compromising visits to the AMS or production parameters when offering less concentrate. However, more data is needed before such strategies are widely recommended.

Composition of the concentrate

In an AMS, special attention is given to the composition of the concentrate in order to attract cows to the robot and increase their visits. Typically, the concentrate mixture is made up of over 50% grain, either ground or pelleted. Studies have shown that cows prefer a mixture of barley and oats and that the type of carbohydrate (starch versus high digestible fiber) does not affect their visits to the robot. Additionally, one study found that cows preferred corn gluten feed over other highly palatable feedstuffs.

While a high-starch pellet is commonly used to encourage cows to visit the automated milking system, there are concerns about the potential negative effects of high-starch intake on rumen pH, feed intake patterns and overall DMI. In a study comparing the effects of feeding high-fiber and high-starch pellets at different feeding amounts alongside a complementary PMR, researchers found no difference in milk production among treatments. This suggests that the composition of the PMR may have a greater influence on feeding behaviors and rumen fermentation than the type of pellet fed. Therefore, PMR formulation is crucial in optimizing milk production in automated milking systems.

Regardless of cows’ preferences, using more than one feed bin to deliver concentrates to the robots is becoming more common. Having more than one concentrate available to feed cows milked in the same robot allows nutritionists to formulate, using one PMR, diets that can precisely meet cow's individual requirements, even if cows in a pen are in very different production stages. One interesting strategy is to formulate one protein and one energy concentrate and feed individual cows different proportions and quantities of the two to meet their requirements according to milk yield, body weight, stage of lactation and even milk components. 

As a rule of thumb

• Do not feed more than 5 lbs. of concentrate per milking.
• If possible, avoid feeding more than 9 lbs. of concentrate daily.
• When working in a pen where cows have homogeneous milk production, formulating a more nutrient-dense PMR and feeding less concentrate in the robot may be the best option.
• There will be a difference between the amount programmed, delivered and consumed, so minimizing the amount of pellets fed will minimize the variation between amounts delivered and consumed and increase the possibility of formulating diets that can better predict production outcomes.
• Remember that PMR represents the bulk of nutrients; feeding high-quality forages and having good feeding management is essential for AMS as for any other dairy system.

This article was written as part of a collaborative program of Michigan State University Extension and the Cornell Cooperative Extension Southwest New York Dairy, livestock and field crops program.

For additional information or if you are interested in discussing concentrate feeding strategies in AMS operation, please do not hesitate to contact Michigan State University Extension / dairy team personnel. To contact an expert in your area, visit https://extension.msu.edu/experts, or call 888-MSUE4MI (888-678-3464).