2013 Robotic Farm Survey: Nutritional Findings
The 2013 Robot Farm Survey conducted by the Ontario Ministry of Agriculture, Food and Rural Affairs and the University of Guelph included 33 automatic milking system (AMS) herds across the province and covered various topics, including management, production and nutrition. This article focuses on the survey's nutritional findings, including type of pellets offered, dietary energy and protein content, particle size and water quality.
Energy-corrected milk (ECM) reveals the amount of energy in milk based on milk's weight, as well as the fat, standardized to 3.5 per cent, and the protein, standardized to 3.2 per cent. Using ECM provides a standardized milk production value that can be used to compare milk with different fat and protein levels and evaluate a herd's feed efficiency. The study found the average ECM was 36 kilograms of ECM per cow per day. This was above the provincial average of 32.2 kg ECM per cow per day.
Nutrition and feeding in AMS herds differs from herds fed a total mixed ration (TMR) since the ration must be balanced between the partial mixed ration (PMR) in the feed bunk and what is fed in the robot. The study included herds with various diets, with some featuring multiple robot pellets and others using high-moisture corn (HMC), mash feeds or multiple PMRs. Researchers sent samples of each farm's PMR and robot feed to a laboratory for analysis.
The nutrient content of the concentrates fed in the robot varied between farms. Of the 33 producers in the study, only 11 fed their herd just one pellet in the robot. The rest provided more than one feed option at the robot. The average pellet consumption in the robot was 4.0 kg per day. Five of the farms provided pellets with HMC in the robot, and six provided an additional pellet, such as a transition or peak-milk pellet. Three producers provided some form of mash feed, with one of them feeding the mash in electronically-controlled feeding stations elsewhere in the barn away from the robot. One producer fed only HMC in the robot.
Many of the producers in the study wanted to feed HMC as a part of their robot concentrates. Farms that used HMC had mixed opinions since there are issues with the flow of HMC into the robot via the bin or auger, improper dispensing, and drops in production and spoilage. However, some producers were happy with the results they saw in their herds, and appreciated the feed cost savings while using HMC, despite some of the logistical complications.
Producers can tailor their robot rations since each cow is milked independently. Feeding groups can be divided in several ways. However, the study found feeding in two groups-milking heifers and milking cows-is the most common. These groups are then subdivided based on production over lactations, after 35 to 40 days in milk.
When formulating a ration, an important factor to consider is its particle size distribution. Proper particle size ensures your cows are getting the right amount of effective fibre and helps maintain a palatable ration. The researchers took a sample of each farm's PMR and performed a Penn State shaker test to evaluate particle size. The results for particle size distribution are shown in Figure 1. The study found a larger proportion of particles on the top tray compared with the standard Penn State recommendations. However, the values were similar to past Ontario research with on-farm data. Inadequate particle size can lead to negative health effects in your herd, such as sub-acute ruminal acidosis.
Milk's protein level is related to the ration's protein level. Pellets ranged in crude protein (CP) levels of between 17.92 per cent and 45.69 per cent. The average CP of the pellets was 24.5 per cent. On average, cows consumed 0.88 kg of CP per day through the robot pellets, not including the additional CP they received from the robot additives. The four pellets highest in CP also fed HMC corn in the robot concentrates, which was the main reason for using a higher CP pellet formulation. These farms fed less pelleted feed in the robot, with the average intake for these farms being 2.34 kg of pellets per cow per day.
The quantity of Neutral Detergent Fibre (NDF) a cow consumes affects the total dry matter intake, and should be monitored when balancing any dairy rations. The NDF of the pellets ranged from 6.79 per cent to 36.96 per cent, with an average value of 24.39 per cent.
Energy, which is provided in the diet through the PMR, pellets and any additional feeds, is important for maintaining a cow's health and meeting its production requirements. The amount of energy in each ration component varies. However, the study found the average net energy lactation (NEL, dry matter basis) of the PMRs was 1.65 mega-calories (Mcal) per kg and the average NEL of the pellets was 1.91 Mcal per kg. Figure 2 shows the net energy provided by the pellet and the PMR for each farm along with the ECM for each farm.
The researchers took water samples from each farm and sent them for analysis to determine the quality of the livestock drinking water. In Ontario, certain situations require producers to treat or filter their cows' drinking water to remove excessive minerals to ensure the water is palatable. For example, elevated iron levels in water are a fairly common problem. Of the 33 farms surveyed, only three had iron above the recommended upper limit. High iron can be addressed through on-farm filtering systems.
Nutrition is important in any herd and is the largest variable cost on dairy farms. The information collected in the study indicates feeding protocols on AMS farms varies greatly. Pellets are relatively expensive, which is why producers want to learn about new ways to decrease their overall feed costs. Using HMC and other pellet alternatives in robot feeding systems is becoming increasingly popular as producers' experience with feeding approaches develops. This type of experience is important when formulating rations for an AMS herd because you have to consider all the options to determine what your herd needs, while making the ration cost-effective.
Michelle Linington and Vanja Djukic were the summer students for this project. Vern Osborne and John Cant are professors in the University of Guelph's department of animal and poultry science, and Tom Wright is the dairy nutritionist for OMAFRA. Reference: A. D. Sova, S. J. LeBlanc, B. W. McBride, T. J. DeVries. 2014. Accuracy and precision of total mixed rations fed on commercial dairy farms. J. Dairy Sci. 97:562-571.
This article was originally published in the September 2014 edition of the Milk Producer Magazine.
Figure 1. Particle size results from robot PMR particle size analysis and comparisons with the Penn State TMR recommendations and the results of Sova et al. 2014.
Figure 2. Source (pellet or PMR) and amount of net energy in the diet and energy-corrected milk yield from the farms that were using the services of CanWest DHI.
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