Taking Stock: Understanding Feed Inventories Now for Strategic Winter Feeding

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Source: Ontario Ministry of Agriculture, Food and Rural Affairs

Understanding feed inventories in advance of winter feeding can help you anticipate any shortages and plan accordingly. Without this information, you may find yourself in a situation where your feed costs are higher than expected or performance takes a hit. However, if any winterfeeding shortages can be anticipated in advance, feeding strategies that will help you stretch supplies can be implemented and abrupt ration changes can be avoided. Two fundamental pieces of information are needed to assess your feed inventories and determine if your feed stores are adequate for the winterfeeding period:

  • The quantity and quality of feed you have stored
  • Animal requirements

Assessing Stored Feed

Understanding the amount of forage stored on a dry matter basis allows for an accurate comparison of the amount of stored forage to anticipated intake. Weight and moisture content are two variables necessary to calculate the total amount of dry matter in stored baled forage. Keep in mind that these variables can differ between lots and cuts. Moisture content can be measured using a Koster tester, a microwave oven test (with less accuracy), or through lab analysis. Table 1 provides an example of an inventory calculation for baled hay.

Table 1. Example of inventory calculation for baled hay

Hay type Moisture (%) Average weight of bales (lbs) Number of bales Dry matter per bale (lbs) Total dry matter (lbs)
1st cut dry hay – home farm
12
1000
125
880
110,000
1st cut dry hay – purchased
14
900
40
774
30,960
2nd cut wrapped – home farm
55
1400
80
630
50,400
Total Dry Matter (lbs)
191,360

Adapted from Hamilton, Kyle, and Potter (2007)

The amount of feed contained within a bunker silo can be calculated if the capacity of the bunker silo, feed type and density of the stored feed are known. Silage density can be determined by taking cored samples from the bunker and weighing them against the known area of silage removed from the bunker. Alternatively, silage density can be estimating using tables available through the University of Wisconsin Team Forage Harvest and Storage website.

For example, a filled bunker silo with dimensions of 20′ x 12′ x 40′ has a volume of 9600 cu ft (width x height x length). If the density of the silage is determined to be 45 lb/cu ft (as-fed), the total weight of the bunker is: 9600 cu ft x 45 lb/cu ft = 432,000 lb (as-fed). At 65% moisture, the weight expressed in dry matter is 151,200 lb.

The University of Wisconsin Forage Team website has some excellent calculators to help estimate the amount of ensiled forage in storage, including a silage pile capacity calculator, silage pile dimension calculator, bunker silo density calculator, and bunker silo sizing calculator. These resources can be found at www.uwex.edu/ces/crops/uwforage/storage.htm.

Animal Requirements

To understand livestock requirements, livestock type (cows, weaned calves, yearlings, etc.) and numbers of each must be known. Rules of thumb can be used to estimate dry matter intake at various stage of production (Table 2).

Table 2. Forage intake “rules of thumb” for cattle (% of body weight)

Straw and poor quality forage Medium quality forage Good quality forage
Growing and finishing cattle
1.0
1.8-2.0
2.5-3.0
Dry mature cows and bulls
1.4-1.6
1.8-2.0
2.3-2.6
Lactating cows
1.6-1.8
2.0-2.4
2.5-3.0

Adapted from Okine and Yurchak (2004)

Table 3 provides an example of calculating total forage needs for your herd.

Table 3. Example calculation to estimate forage requirements, assuming intake of good quality hay at 2.5% of body weight (dry matter/day)

Animal type # of animals Average weight (lb) Length of feeding period (days) Forage requirements per head per day (lbs of DM) Total forage requirements over feeding period (lbs of DM)
Dry cows
70
1300
270
32.5
614,250
Bred replacement heifers
11
900
270
22.5
66,825
Weaned replacement heifers
10
600
270
15
40,500
Total DM requirements over feeding period (lbs)
721,575

Adapted from Hamilton, Kyle, and Potter (2007)

As Table 1 suggests, forage quality will influence grain and supplementation needs. Intake of lower quality forage is limited due to its slower rate of passage, so supplementation with grain will likely be required to meet energy requirements. Environmental conditions will also influence supplementation needs. For example, the energy requirements of cattle typically increase in the winter due to cold temperatures, moisture, and wind.

Other Important Considerations

While the “rules of thumb” provide approximate forage intake figures to help assess inventory and consumption, it is important to also understand the quality of your feed. Feed testing and working with a nutritionist to formulate rations are recommended practices to ensure the nutritional requirements of cattle are being met and input costs are minimized. Any potential for spoilage must also be considered and factored into your inventory assessment. Dry matter losses for covered dry hay bales, elevated or on a pad, can amount to 4% to 17%, while uncovered dry hay bales stored on the ground can yield inventory losses from 5% to 61%. Table 4 provides figures on typical losses associated with various storage methods for ensiled forages.

Table 4. Typical losses associated with various storage methods

Silo Type Moisture (%) Total DM Losses (%)
Silage bags
60-70
9-14
Wrapped silage bales
50-60
15-20
Upright tower
65
13-19
60
11-17
50
11-17
Bunker, no cover
70
24-34
60
30-43
Bunker, covered
70
16-23
60
18-34
Stack, no cover
70
37-47
60
45-58
Stack, covered
70
17-27
60
21-34

Adapted from Holmes and Muck (2000)

When You Have a Feed Shortage

If you determine you will be short of feed, consider strategies that will help you stretch supplies:

  • Extended or alternate grazing options. If conditions will allow, consider extended grazing on stockpiled pasture, corn stubble, or cover crops into the fall. The more forage cattle can consume on pasture, the less stored forage must be used in the winter months. Explore opportunities for custom grazing or leasing land for cover crop grazing. Strategies such as strip grazing can help to minimize waste and make the most of the forage available for grazing. Using the example of 70 beef cows from Table 2, if the grazing period is extended by 30 days into the fall, the amount of stored forage required over the feeding period can be reduced by 68,250 lb (dry matter).
  • Reduce spoilage and waste during feeding and storage. Nutrient and dry matter losses can be minimized with proper storage. Waste during feeding can be reduced by using feeders that limit losses. Feed waste eats into your forage supply.
  • Purchase feed or identify alternative feed sources. Work with your nutritionist or feed consultant to determine cost-effective feed ingredients that can be included in your ration to stretch forage supplies. Freight costs, dry matter content, storage capacity, and product shelf-life must all be considered when assessing alternative feed ingredient options.
  • Reduce stress from cold temperatures, moisture and wind. Exposure to the elements increases energy requirements and dry matter demand.
  • Wean calves early. Early weaning of calves reduces the energy demands on dams and helps to preserve forage on pasture. The benefits of early weaning must be assessed against market prices for calves in a given year.
  • Culling/liquidating. Start with culling open cows and heifers, and then consider cows and bulls with health, conformation, and performance issues.

References

Hamilton, T., Kyle, J., and Potter, B. 2007. Dealing with shortages on your beef farm. Ontario Ministry of Agriculture, Food and Rural Affairs.

Holmes, B. 2012. Making a Feed Inventory. University of Wisconsin-Madison.

Holmes, B. and Muck, R. 2000. Preventing Silage Storage Losses. University of Wisconsin-Madison.

Okine, E., and Yurchak, T. 2004. Beef Ration Rules of Thumb. Alberta Government.

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