Nutritionists typically expend a lot of effort and time formulating rations for their clients. The same amount of nutritional expertise goes into the development of each of these rations, but their apparent success and consistency can vary tremendously from dairy to dairy (Figure 1). Although there are obviously a great number of farm management variables (stall comfort and hygiene, water availability, ventilation, parlor management, forage quality, etc.) that influence production, there are also many areas in feeding management that strongly influence the success of the formulated ration (Barmore, 2002). This paper will address the major factors I see increasing the amount of variation between formulated and consumed rations.
Feeding Management Variables that Reduce Ration Accuracy and Consistency
The three main areas that have the greatest potential for altering the formulated ration from the consumed ration are the feeds, the feeder, and the cows.
Feedstuff Variation
One of a nutritional consultant’s responsibilities is to have an accurate analytical description of the feeds used in a dairy’s ration. Tabular values are often used in ration formulation for concentrate feeds. This is completely acceptable, as long as one is sure that the tabular values used accurately describe the feeds. Some concentrates are more variable than others (St-Pierre, 2001). Ration variation can be reduced by using feedstuffs that are more consistent, and by designing a ration with an increased number of feedstuffs. Multiple feedstuffs reduce variation since the variance of a feedstuff (or any variable) increases by the square of the amount of the feedstuff. Rations can be balanced closer to an animal’s requirements when these concepts are implemented (St-Pierre, 2001).
Feeders should evaluate commodity loads prior to or immediately following unloading for any signs of mold, contaminants, DM, color, temperature, and odor. Areas of concern should be addressed and the load potentially rejected.
Figure 1. Daily average milk production from two dairies. There is much more daily variation evident in Herd B than in Herd A. An unrelated fourteen day BST cycle is also evident in Herd B, which used BST.
Forages, and haylages in particular, have a large potential for variation. The degree of variation at a given dairy depends largely on its ability to manage their cropping and harvesting systems. One advantage that bunker silos have over upright silos and bags is that ensiled feed from a given load or field is spread over a larger area of the silo. Thus, changes in forage dry matter (DM) or chemical measurements occur more gradually than in other storage systems. However, variation can still occur across the height of a silo. To estimate this potential variation, eleven corn silage and nine haylage bunker silos from nine dairies located in central New York were evaluated (Stone et al., 2003). Samples were collected on six dairies with a backhoe, on two dairies with a loader bucket, and on one dairy with a face shaver. Sample collection was designed to reflect the feed that would be obtained if a feeder obtained a loader bucket of feed from a region (upper, middle, or lower) of the silo as compared to a bucket obtained from the entire height of the silo face. Silos above (n = 15) approximately four meters in height were split into thirds for sampling, while those less (n = 4) than approximately four meters were split into halves. The vertical trench was dug to a depth of about .2 - .3 meters. Experimental feed within each section was thoroughly mixed and then subsampled to obtain a sample approximately 5-10% the size of the removed silage pile. This sample was then again thoroughly mixed and finally subsampled for analysis of DM, ADF, NDF, CP, lactate and VFA with wet chemical procedures (Dairy One, Ithaca, NY). The entire approximately 3 liter sample was ground for analytical procedures.
Two test silos (one alfalfa and one corn silage) were used to evaluate the consistency of the sampling and the laboratory procedures. The sampling procedure described above was duplicated once for each silage pile obtained from the upper, middle, and lower sections of the silos. These samples were then examined in triplicate for DM and NDF, and singly for ADF, CP, lactate, and VFA to compare the consistency of sampling and laboratory procedures. Generally, the results were very consistent (Figure 2). This indicates that the measured variation within silage regions was actually occurring.
Figure 2. A trench was dug into the corn silage test silo with a backhoe. The silage was placed into piles obtained from the upper, middle, and lower thirds of the silo. The piles were mixed with a silage fork, subsampled twice, remixed, and then sampled for analysis. The two subsamples obtained from each region of the silo were tested in triplicate for DM. The results were very consistent.
Within each silo, deviations from the minimum analytical result for DM, ADF, NDF, CP, and VFA were determined. Maximum deviations within a given silo were determined by dividing the range by the minimum analyzed value. For example, a silo with measurements of 44.5, 41.2, and 36.6 would have a maximum deviation of 21.6%.
Haylage varied more than corn silage (Table 1), although there were examples of extreme variation, particularly in DM, in both crops. In some situations a feeder could be delivering an entirely different ration from one load of feed to the next if care is not taken in forage obtainment from the silo. For example, a 54.5% forage ration can range from a 46 to a 63 percent forage diet if the feeder erred in the same direction by the average deviation for both haylage and corn silage when preparing a load of feed. Dairy feed personnel need to be aware of this variation, and of the difference it can make to the final ration delivered to the cow. Techniques to minimize forage variation, such as obtaining each bucket of feed from the height of the silo face or the premixing of forages obtained from across the entire face of the silo, should be part of feeding standard operating procedures on dairies. Not only do silage face shavers vastly improve bunker face management, but they also reduce ration variation by mixing forages from across the height of the silo.
| Haylage results |
DM |
CP |
ADF |
NDF |
NEL |
lactic |
Actetic |
Total VFA |
| Minimum deviation, % |
44.7 |
52.1 |
20 |
24.8 |
20 |
646 |
163 |
287 |
| Maximum deviation, % |
44.7 |
52.1 |
20 |
24.8 |
20 |
646 |
163 |
287 |
| Average deviation, % |
21 |
17.6 |
10.7 |
14.7 |
9.9 |
112 |
72 |
69 |
| Median deviation, % |
19.4 |
9.5 |
9.9 |
14.4 |
9.3 |
57 |
50 |
38 |
| Corn silage results |
|
|
|
|
|
|
|
|
| Minimum deviation, % |
1.3 |
2.5 |
2.3 |
0.5 |
1.4 |
3.8 |
11.2
|
0.1 |
| Maximum deviation, % |
55 |
29.5 |
18.3 |
18.6 |
5.6 |
48.7 |
131 |
41.3
|
| Average deviation, % |
12.3 |
11 |
8.4 |
8.6 |
3.1 |
25.6 |
53.7
|
20.5 |
| Median deviation, % |
8.3 |
10 |
8.6 |
8.4 |
2.8 |
26 |
29.9 |
21.4 |
Variation like this must be considered during the collection of a sample for DM or a more complete analysis. Probably the ideal method to collect a forage sample from a bunker silo would be similar to that used in this study. A backhoe (or silage face shaver) would be used to dig a trench near the midsection of the silo, this forage would then be mixed in the mixer wagon, discharged, subsampled, remixed, and finally sampled for analysis.
The recommended frequency of testing for DM and laboratory analysis really varies with the dairy. As a minimum, ensiled forages should be tested weekly for DM and monthly with a more complete laboratory analysis. More frequent analyses should be run if there is significant variation. The feeder should know the relationship between on-farm measured DM and those generated by the laboratory from a split sample of the same feedstuff. Maintaining a DM log from these split samples helps immensely in developing a dairy – laboratory DM relationship.
Feeder Responsibilities to Minimize Load Variation
Obviously, the performance of the feeder is an integral component in the accurate preparation of a load of feed. The nutritional consultant, along with the dairy owner or manager, needs to closely work with this individual. The feeder must understand how many seemingly small things can have a huge influence on animal performance. Specifically, they should have an understanding of the following areas:
- Dry matter – what it is, why it is important, and how it should be calculated. Bucholtz (1999) reports that most feeders attending MSU Feeder Schools were uncomfortable with arithmetic, and had a poor understanding of the DM concept.
- Face management – methods to keep the silage face straight, with minimal disturbance of packed silage, and minimal amounts of loose feed left at the end of feeding.
- Silage collection for load preparation – ideally silage is premixed or removed with a face shaver to minimize variation across the bunker.
• Spoiled silage – poor quality silage that may be located along the top and sides of the silo should be removed so that it does not impair animal performance.
- The potential effect on animal performance of layers of feed within the bunker that are of poor quality.
Load preparation
- Ingredient sequencing – what order works best?
- The importance of accuracy when loading an ingredient into the mixer wagon.
- Mixer operation - When it should be started, length of time and speed that it should run, and minimum and maximum load sizes.
- Mixer wagon maintenance
Being a feeder is a difficult, highly important position on a large dairy. Effort should be made to make it easier for a feeder to achieve the results desired of them. Ingredient mixes should be purchased or made on the dairy. This greatly minimizes the number of separate ingredients that must be added to each load, and increases the feeder’s speed and accuracy. Load sheets should be printed in a font size that is easy to see, and with multiple forage DM increments and animal numbers. Scale displays should be easily visible from the loading tractor, and should have a remote that allows the scale to be zeroed after the addition of each ingredient.
Several of the commercially available computerized feed management software systems perform all of these functions, and more (Bucholtz, 2002). The systems can improve a feeder’s accuracy and efficiency both through making their responsibilities easier to accomplish, and through making the feeder more responsible since he/she can now be monitored. Dry matters and rations can be updated by the feeder in the bunk, or by someone else at the dairy office. The change in ingredient dry matter is updated in all rations. The systems typically come with a highly visible scale display. The systems can also record the accuracy with which each ingredient was added to a load, the time between ingredients, the time needed to prepare the entire load, and the total mixing time. Providing cow numbers are correct, an accurate assessment of dry matter intake can be obtained. Additionally, the software systems help in inventory management and to reduce shrink.
Cow and Bunk Management Effects Influencing the Consumed Ration
Cow sorting can lead to multiple “rations” being consumed by animals fed the same ration. Signs of sorting include “holes” eaten into the offered feed that contain more forage and less grain than the remaining feed; a ration that looks and analyzes differently throughout the day; and variation in manure consistency, particle size, and grain amount.
The Penn State particle separator (Lammers et al., 1996) is a useful tool to evaluate the uniformity of ration consumption throughout the day.
Manure evaluation at this time is quite subjective (Hall, 2002a). Manure can be screened with any device containing a screen size that is approximately 1/16”. I use a wooden box approximately 16” (40 cm) square, 3” (7.6 cm) deep, with 1/16” (.16 cm) wire screening stapled to the bottom. Approximately 1.5 cups of manure can be collected from multiple representative cow piles throughout a group, placed on the screen, and then gently washed with a spray of water. Results should be quite consistent across manure piles; if not, sorting may be an issue.
Sorting of the ration by the cow can result in the consumption of a very inconsistent ration. Typically long particles are selected against, resulting in some meals having a much greater grain content than intended (Leonardi et al., 2000 and 2001; Martin, 2000). Sorting can easily result in subacute ruminal acidosis.
Sorting can be minimized by avoiding excessive amounts of long material in the TMR. Added hay or straw should not be longer than 2.5 to 5 cm (Hall, 2002b; Shaver, 2002). Wetter rations help the various feeds to stick together, thus making it more difficult to sort. Water, or wet feeds such as wet brewers grain, can be added to reduce ration DM to less than ~ 50%, or to a level that acts to reduce the sorting problem (Shaver, 2002). Palatable feeds are less likely to be sorted than unpalatable feeds (Leonardi and Armentano, 2000). And finally, the addition of molasses has reduced sorting, particularly when added to the TMR (greatest reduction) or forage (Shaver, 2002).
Bunks should be managed so that adequate feed is available along the entire length of the bunk at all times. Feed needs to be pushed up frequently enough so that this is achieved; usually 8-10 times per day is necessary.
Group intakes should be within approximately 5% of the formulated diet. Otherwise, the formulated diet is not truly being consumed, and the nutritional consultant may need to make a ration intake adjustment.
REFERENCES
Barmore, J. A., 2002. Fine-tuning the ration mixing and feeding of high producing herds. Tri-State Dairy Nutrition Conference, Fort Wayne, IN, pp. 103-126.
Bucholtz, H. 1999. Communicating with the person mixing the feed. Tri-State Dairy Nutrition Conference, Fort Wayne, IN, pp. 204-208.
Bucholtz, H. 2002. New feed management software. Tri-State Dairy Nutrition Conference, Fort Wayne, IN, pp. 99-101.
Hall, M. B. 2002. Manure evaluation: a practical tool for reading your cows. Proc. Cornell Nutr. Conf., 64th annual meeting, Syracuse, NY, pp. 145-152.
Hall, M. B. 2002. Rumen acidosis: carbohydrate feeding considerations. Pages 51-69 in Proceedings from the 12th International Symposium on Lameness in Ruminants. Orlando, Florida.
Lammers, B. P., D. R. Buckmaster, and A. H. Heinrichs. 1996. A simple method for the analysis of particle sizes of forage and total mixed rations. J. Dairy Sci. 79:922-928.
Leonardi C., L. E. Armentano and K. J. Shinners. 2001. Effect of different particle size distribution of oat silage on feeding behavior and productive performance of dairy cattle. J. Dairy Sci. 84(Suppl. 1):199 (abstr.).
Leonardi C. and L. E. Armentano. 2000. Effect of particle size, quality and quantity of alfalfa hay, and cow on selective consumption by dairy cattle. J. Dairy Sci. 83 (Suppl. 1):272 (abstr.).
Martin R. 2000. Evaluating TMR particle distribution: a series of on-farm case studies. Pages 75-78 in Proc. 4-State Prof. Dairy Mgmt. Seminar. Dubuque, IA MWPS-4SD8. Ames, IA.
Shaver, R. D. 2002. Rumen acidosis in dairy cattle: bunk management considerations. Pages 75-81 in Proceedings from the 12th International Symposium on Lameness in Ruminants. Orlando, Florida.
Stone, W. C., L. E. Chase, and T. L. Batchelder. 2003. Corn silage and haylage variability within bunker silos. J. Dairy Sci. 86 (Suppl. 1):168 (abstr.).
St-Pierre, N. 2001. Managing variability in feed programs. Pennsylvania State Dairy Cattle Nutrition Workshop. Grantsville, PA.
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