To achieve this goal, the automated milking system provides us with the opportunity to be more precise and close to nutrient needs for each individual cow. Feed represents 50% to 70% of the costs in a dairy operation, so increasing feed efficiency has a major effect on profitability. The challenge becomes balancing the nutrients provided without compromising rumen health and number of visits to the automated milking system, in order to maintain constant milking frequency and the minimum necessary visits to harvest all our cows’ potential.
The feeding program in the robotic system requires a balance between the partially mixed ration (PMR) based on farm forages, grains, protein, premix and a complementing robotic feed fed at the milking station. So then what are the factors we should analyze when we select the robotic feed?
Energy and palatability
Energy and palatability are the main drive to the robot in the free-flow automated milking system. So for the PMR, the energy concentration is balanced to target a milk production of 7 liters (1.85 gallons) less than the farm’s average production. The feeding table of the automated milking system will supply the rest required based on each cow’s needs.
When a different concentrate composition of the automated milking system feed pellets was evaluated on intake in a 2009 experiment, the cows preferred a wheat-based concentrate and a mixture of barley and oats over pellets based on maize or barley alone. In this study, the cows did not like the fat-rich or the pure-dried grass concentrates used. However, there was a good acceptance of dried grass pellets in another study. The acceptance of some ingredients was increased by adding sugar beet molasses, pelletized peas and dried sugar beet pulp. The ranking of preference could also change by either pelletizing or rolling the grains, with pelletized preferred to rolled.
Amount fed, milk production and feed waste
The amount fed at the automated milking station should be a balance of several factors: the basal PMR, the total amount required by the diet, pellet refusal and waste. Offering amounts higher than 3 kilograms (6.6 pounds) of concentrate in the automated milking system when feeding a basal PMR rich in corn silage did not diminish the need for fetching cows nor increase the number of visits and daily milkings in one research study. However, if the PMR is low in energy concentration, then the amount of concentrate offered can have a significant positive effect on visit frequency.
When we analyze the target automated milking system feeding rates and PMR energy composition, we must balance nutrition, feed cost and returns. Unfortunately, providing more energy and, therefore, cost is not always reflected in income. Feeding more than 2.3 kilograms (5 pounds) of feed in the robot per visit has been demonstrated to increase wasted feed.
In a feed-first, guided-flow barn, either a high-concentrate PMR (54-46 forage-to-concentrate ratio) or a high-concentrate automated milking system feed (21.4 percent total diet) tended to have greater milk yield. But the high-concentrate automated milking system program had more variability in the day-to-day consumption at the robot. This results in more or variable amounts of pellet refusals to control. On the other hand, the program with a high-concentrate PMR had a greater holding area time.
Feeding a high-concentrate PMR may have reduced motivation to enter the automated milking system based on greater time spent in the holding area compared to cows fed a high-forage PMR (64-36 forage-to-concentrate). It did not affect the number of visits to the robot in this study, but the cow activity (hours standing) and flow in the barn changed (traffic and blocking the automated milking system). The time spent standing and blocking the robot entrance reduces the flow and affects hoof and leg health, which brings other management challenges.
Rumen function
In a free-flow automated milking system, the cows usually consume approximately 3 to 4 kilograms (6.6 to 8.8 pounds) per day of starchy pellets in the robot, complemented with a PMR containing a level of energy balanced for the average farm production (target of 7 liters [1.85 gallons] less). But this feeding regimen is not very effective to sustain high-yielding cows that produce 50 to 60 liters (13.2 to 15.85 gallons) per day. Increasing the amount of pellets fed in the robot or in a concentrate self-feeder located after the robot can be desirable to improve energy balance.
However, studies have shown with a high intake of starchy pellets in a short time, the starch has inhibitory effects on digestibility, and the rate of fiber digestion by ruminal bacteria decreases. The rumen pH decreases, and this upsets ruminal fermentation. In serious cases, appetite is impaired, lowering voluntary intakes of dry matter (also fiber), cascading further negative effects on rumen health and milk production.
We must encourage higher-frequency visits to the robot without upsetting the rumen or dramatically decreasing PMR consumption and total dry matter intake (DMI) per day. In a study that included fiber in the pellets instead of starchy grains, neither voluntary milking frequency nor milk yield and composition was affected for high-producing dairy cows (semi-free-flow automated milking system). This finding suggests both types of pellets have an accepted palatability, and fiber in the pellets may be used to partially or totally replace the conventional starchy pellets in the automated milking system. This would allow larger allocations of pellets or having two different pellet options that will not interfere with PMR consumption or more visits.
We can evaluate the option of feeding multiple pellet types at the automated milking system, adding a concentrate self-feeder on the alley or using on-farm grains or mixes, but this will require an increased level of management by the producer to ensure good intakes, appropriate feed flow and delivery, and desired performance. In a 2013 survey in Ontario, 15 percent of 33 farms were using high-moisture corn (HMC) in the robot feeder. Reported issues included poor flow, improper dispensing, constantly monitoring for spoilage and drops in production. Others using a 40-60 mix of HMC-pellet reported being quite pleased with it. The HMC herds only had a pellet intake of 1.4 to 3.8 kilograms (3.1 to 8.4 pounds) per cow per day.
To maximize the use of your feed and to be more precise and close to nutrient requirements, the feeding program in the robot system should be discussed with your nutritionist, monitored and balanced frequently according to your on-farm feeds (PMR). Feeding efficiency at the automated milking system could be improved by combining two types of concentrates and by restricting the concentrate allowance to minimize waste or upset rumen degradation patterns. The PMR delivery time has been shown to be a strong motivating stimulus for cows to visit the robot. Consider pivotal aspects of the PMR like mixing, monitoring moisture and bunk management. Continuous review of your feeding program as part of the on-farm management strategy ensures robot feeds are being used to maximum benefit for on-farm profitability. 
References omitted but are available upon request. Click here to email an editor.
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Sylvia Borucki
- Ruminant Nutritionist
- New-Life Mills
- Email Sylvia Borucki
