MANAGEMENT ASPECTS OF IMPLEMENTING PRECISION FEEDING OR HIGH CONCENTRATE, PRECISION FEEDING SYSTEMS
Weigh Heifers Often
There is probably no management tool that impacts more aspects of heifer rearing than monitoring the weight of heifers. Weighing and monitoring heifers frequently is especially critical for precision-feeding systems. Critical times to weigh heifers would include after weaning, before breeding, at breeding, at pregnancy confirmation, and prior to calving. Average daily gains should be calculated and body condition scores should also be monitored. Based on research ADG of Holstein heifers should be 1.75 to 2.00 pounds per day.
Weighing heifers is a relatively simple means to monitor animal performance, and this practice is a must for precision feeding dairy heifers successfully. Weighing heifers is increasingly important when precision feeding dairy heifers since an inappropriate level of diet restriction can lead to rapid gains and fat heifers or gains lower than desired. Electronic scales can be placed in alleys or some other easy to handle location to make heifer weighing less of a chore. Basically any time a heifer is handled, she should be weighed. With a precision feeding system heifers must be weighed to allow you know what amount of feeding is required, while maintaining the growth rates needed for breeding at a given age or for calving at a given body weight.
Recommendations:
Weigh heifers at the same time of day (relative to feeding), otherwise alterations in gut fill can impact ADG calculations.
Weighing heifers once per month is best, but once your system is stable, less frequent weights can work as long as you at least observe body condition.
It is best to weigh all heifers; however, on some farms it may not be realistic, as heifer numbers may be labor prohibitive. In this case, weighing a representative group of heifers in a pen each time will suffice. It is important to be sure that this group is representative of the entire group and that the same heifers are weighed each time.
Monitor individual heifer and group gains against benchmark weights, and alter management, specifically feed intake strategies, as needed.
If you are in need of a generic spreadsheet to monitor heifer weights and average daily gains, one is available at: www.das.psu.edu/dairynutrition/heifers
Group Sizes
In any group-housed heifer facility minimizing variation in size and age of heifers in each group is important, and it remains important in precision feeding system management. Typically, beyond 4 months of age, heifers should be housed with other heifers as close to the same age as possible and always in groups with less than 200 pounds (90 kg) of weight variation within the group. Often this means having groups with 2 to 4 months of age variation at the most. Post breeding, this number can be increased to 300 pounds (136 kg) weight spread between animals within a group.
Feed Bunk Space
In precision feeding systems, heifers will need 14 to 24 inches of feed bunk space per heifer as they progress from 4 months of age to pre-calving or 22 months of age.
Precision-fed heifers will not have access to feed at all times of day, thus all heifers in a pen must have access to the feed bunk. Overly aggressive and timid heifers are very susceptible to over- or under- nutrition when feed bunk space is limited. Therefore, it is imperative that all heifers are able to eat at one time.
There are three strategies that can be used when feed bunk space is limited. The first is clearly grouping animals with peers having similar body weight. The second strategy is to have impediments to free motion at the feed bunk, such as headlocks or closely placed divider posts. This will likely be effective to some degree, but not completely. The third is to feed twice daily at close intervals. For example, feed two- thirds of the daily allotment at 7 a.m. and the remaining third at 9 a.m.; in this way the larger animals can eat more freely at the early feeding and the more timid animals at the second feeding.
Avoid Straw & Wood Shavings as Bedding
Precision feeding dairy heifers is based on meeting energy requirements through a producer-imposed restriction—not by gut fill limiting DMI. Since gut fill and ADG potential will not be maximized, heifers will readily consume edible bedding, which will reverse many of the advantages obtained by precision feeding. If heifers are allowed to consume bedding material the intended balance of the precision-fed diet is compromised. Precision-fed heifers require balanced diets to grow at the desired level. A balanced ration under precision feeding requires complete consumption of the diet that is presented to them each day without consumption of free choice supplemental forage or edible bedding of any kind.
Hungry, But Growing
At the initial implementation of the precision feeding protocol, the heifers will likely vocalize immediately prior to feeding, with the frequency and magnitude increasing toward the next feeding. Research experiences are that this behavior will diminish and virtually disappear by between 10 and 14 days after the implementation of the precision feeding strategy. This is due to a moderate reduction in rumen and gut size needed to accommodate a reduced digestive load, which is one of the reasons for the improved efficiency in precision-fed heifers.
The transition to precision feeding requires time and commitment in a manner similar to the time it takes to increase gut capacity after calving. As long as the heifers are growing according to the ADG goals of your operation and receiving a correctly balanced ration, they are adequately fed.
Make Small Changes
Transitioning heifers from a high forage diet to lower forage, precision fed diet requires incremental steps to allow for adequate rumen adaptation. Research at Penn State has focused on precision feeding heifers high concentrate diets in an effort to learn about the advantages and disadvantages of precision feeding systems; however, it is recognized that feeding higher concentrate diets to dairy heifers is a major nutritional and management shift from traditional heifer diets.
An appropriate precision feeding starting point is to limit the intake of a 50% forage, 50% concentrate diet. This type of diet offers some of the advantages of precision feeding a high concentrate diet and will increase feed efficiency as compared to a traditional high NDF, low-energy diet. The aforementioned diet also does not have as high a potential for producing rumen problems as higher concentrate diets (this is logical because most milking cows are fed this type of diet at substantially greater quantities per pound of body weight).
Transition to Pre-Freshening and Post- Freshening Diets
Precision feeding should be discontinued and heifers adapted to normal pre-freshening diets 30 to 45 days before calving. Precision feeding heifers until 30 to 45 days before calving has had no adverse effects on calf birth weight, dystocia, metabolic problems, early lactation intakes, or first lactation milk production, as has been reported in several peer-reviewed journal publications. Changes in rumen and gut volume have been shown to occur rapidly and do not limit postpartum dry matter intake.
