Introduction
Robotic milking systems or automatic milking systems (AMS) are becoming increasingly common on dairy farms in the US and around the world. In these systems, cows are typically fed a partial mixed ration (PMR) at the feed bunk with the balance of the diet fed as a concentrate through the AMS. Most AMS have the ability to dispense multiple feeds and various feed types to cows, however, the majority of farms feed a single pelleted feed at the robot. The amount of pellet an individual cow receives varies from cow to cow and farm to farm; the quantity can be adjusted based on expected milk production, days in milk, and other production related factors on the farm. An average of 10 pounds of pellet per cow per day is typical in AMS.
Quality, consistency, and palatability of feed supplied at the robot is crucial to the management of robotic milking dairy herds. Not only do these play a critical role in the overall nutrition of the dairy cow, but both research studies and experience on farms have demonstrated the important role of the robot feed in motivating cows to visit the robot.
The use of a single pelleted feed being fed through an AMS is driven by ease of dispensing it in the robot. While feeding pelleted feeds has been demonstrated to be an effective management strategy, the pellets can cost $340, or more, per ton. There is interest from dairy farmers in finding ways to improve income over feed costs by utilizing alternative feeds that can be fed through AMS. High moisture corn (HMC) is one alternative; when harvested, stored, and managed correctly it has many desirable qualities. It is palatable, nutritious, available, and according to Penn State Extension research, a typical cost of production on Pennsylvania farms is approximately $60 per ton, making it more affordable than pelleted feed. The biggest challenge of feeding HMC through most AMS is ensuring that it is dispensed evenly and does not bridge or clog the feeder.
The objectives of the current case study were to evaluate the effects of replacing a commercial robot pellet with HMC fed through a novel feed dispenser in an AMS on milk production, animal behavior, and economics.
Methods
Over a 60-day period, cow behavior, milk production, and feed intake were monitored on a commercial dairy farm in southeastern Pennsylvania as it transitioned from feeding a robot pellet to home raised HMC. Cows were milked in an Astrea 20.20 (AMS Galaxy) robotic milker; this system consists of two side-by-side milking stalls with one robotic arm responsible for udder prep and milking unit attachment in both stalls. Approximately 129 Holstein cows were being milked in the AMS during the study period. The AMS recorded cow visits to the robot, milkings per cow, milk production, and the quantity of feed dispensed. Eating and rumination times were recorded using a Nedap (Nedap Livestock Management) activity monitor system. The farm stored HMC in a silage bag and filled the HMC feeder daily with a skid steer. Feed cost per cow per day, and income over feed cost were calculated for the initial Pellet Feeding Period and the subsequent HMC Feeding Period.
Results
During the Pellet Feeding Period, cows received an average of 10 pounds per cow per day of a commercial pellet and no HMC in the robotic milker.
Figure 1. Average pounds per cow per day of pellet and HMC fed through the AMS. The Pellet Feeding Period ran from February 1 – February 20, 2020. The Transition Period ran from February 21 – March 8, 2020. The HMC Feeding Period ran from March 9 – March 30, 2020.
As cows went through the Transition Period, the amount of pellet was gradually decreased and the amount of HMC was gradually increased. At the beginning of the HMC Feeding Period, cows continued to receive a small amount of pellet (less than 1 pound per cow day) before it was phased out completely. After completely transitioning to HMC feeding, cows received an average of 9.3 pounds of HMC per day at the robotic milker.
Average daily milk production per cow increased slightly, from 80.4 pounds during the Pellet Feeding Period to 81.6 pounds during the HMC Feeding Period.
Figure 2. Average milk production per cow per day was 80.4 lbs. during the Pellet Feeding Period and increased (P<0.05) to 81.6 lbs. during the HMC Feeding Period.
Average milkings per cow per day increased from 2.65 milkings during the Pellet Feeding Period to 2.82 milkings during the HMC Feeding Period.
Figure 3. Average milkings per cow per day increased (P<0.05) from 2.65 during the Pellet Feeding Period to 2.82 during the HMC Feeding Period.
Average eating time per cow per day was 239 minutes during the Pellet Feeding Period and increased to 246 minutes during the HMC Feeding Period.
Figure 4. Eating time increased (P<0.05) from 239 minutes per cow per day in the Pellet Feeding Period to 246 minutes per cow per day in the HMC Feeding Period.
Rumination time decreased from 37.6% of the day during the Pellet Feeding Period to 35.7% of the day during the HMC Feeding Period.
Figure 5. Rumination time decreased (P<0.05) from 37.6% of the day per cow per day in the Pellet Feeding Period to 35.7% of the day per cow per day in the HMC Feeding Period
Eating time and rumination time are presented for 2nd and greater lactation cows from 0 to 150 days in milk; results were similar for 1st lactation cows and 2nd and greater lactation cows in late lactation.
In a free flow robotic milking system, such as at the farm where this case study was completed, cows are able to access the robotic milking system any time throughout the day. As a cow enters the robotic milker, she is identified by the system, and if she was milked recently, she will not be milked or receive a feed from the robot during the visit. For AMS Galaxy robotic milkers this visit is referred to as a ‘Not Yet’, as in the cow is not yet ready to be milked. A higher ‘Not Yet’ value indicates that cows are coming to the robot more frequently. Many factors can influence how frequently a cow comes to the robot, but the feed a cow receives at the robot is considered to be a major factor. In the current study, cows increased from 0.35 Not Yets per cow per day during the Pellet Feeding Period to 0.67 during the HMC Feeding Period.
Figure 6. Not Yets increased (P<0.05) from 0.35 during the Pellet Feeding Period to 0.67 during the HMC Feeding Period.
The average feed cost per cow per day during the Pellet Feeding Period was $7.05, and the cost of the robot pellet fed during this period was $296 per ton.
Figure 7. Rations and feed costs for Pellet Feeding Period and HMC Feeding Period.
Average feed cost per cow per day during the HMC Feeding Period decreased to $6.16. High moisture corn was valued at $60 per ton. It is important to note that in the current case study the pellet was not simply replaced one to one with HMC. Dairy producers are encouraged to work closely with their farm’s nutritionist to ensure that animals are receiving a properly balanced ration.
The lower feed costs and increased milk production resulted in an increase in the return of $1.12 per cow per day.
Figure 8. IOFC During the Pellet Feeding and HMC Feeding Periods and return on investment and payback period for transitioning to HMC feeding in a robotic milking dairy.
1$18.50 per cow CWT milk price assumed
2129 cows
This return would result in an annual return per cow of $407 and $52,545 for the farm (assuming 129 milking cows). Assuming the equipment and installation cost for the HMC feeder is $22,500, the investment for this system could be paid for in less than 6 months.
Conclusion
Based on the current case study, installation of an HMC feeding system on dairy farms using AMS is an opportunity to reduce feed cost and improve profitability on the farm. Producers considering this option should first determine that they have sufficient land available to grow and store adequate HMC to feed through their AMS. A second factor to consider is that feed quality is very important with this system. If feed is too dry or becomes spoiled or moldy, palatability will be affected. Decreased feed quality can quickly decrease the cow’s desire to eat the feed, reducing visits to the robot and milk production.
