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Good Feed Value In Crop Residue

Winter seems so far away, but before you know it, most people will have weaned their calves and brought their cows home and provided forages and grain rations harvested during the summer. This cost of winter-feeding gestating beef cows represents between 65 to 70 per cent of the total cost of running a cow-calf operation. However, a lot of crop residues will shortly be at most people’s fingertips and can be turned into good winter feed for beef cows. It only requires a good plan of action on collecting and feeding crop residues to beef cows, well before the first snowflake arrives, which can result in significant savings of winter feed costs.

After harvest, consider that more than half of the entire plant mass of cereal crop such as barley becomes crop residue, once the grain is removed. Straw is leftover stem and leaf residues, while chaff is made up of all parts of the leftover grain-spike; awns, short straw, seed coats and may even contain substantial grain kernels uncollected from the combine.

Either straw and grain chaff can be collected together or the chaff can be collected separately. Then these straw/chaff or chaff-only residues might be blown or stacked into various piles for cattle grazing throughout the field. Another available option is that chaff can be collected and dropped onto the straw swath and be made into straw/chaff bales.

After looking at just these two options (and more that are not discussed), producers might do a complete assessment before making any concrete decision as to how to turn crop residues into overwinter cow feed. They should evaluate a number of respective factors; such as the current type of combine that harvests the grain crop in the first place (re: how straw and chaff exits the combine — separate or in one steady stream), any required crop residue equipment (chaff box, straw/chaff collector and assorted wagons) and most importantly the amount of personal monetary investment, which fits the winter-feeding budget of the an individual’s cow-calf operation.

While penciling out their own potential overwinter cost savings using crop residues, many people should know that such successful crop residue feeding programs for beef cows are based on five underlying points:

Crop residues such as cereal grain swaths, chaff piles, and standing stubble which often contain 41 to 45 per cent TDN, and about 3.5 per cent to four per cent protein. Furthermore, straw and chaff quality varies with type of crop, stage of maturity, weed content, and method of harvest. It is often recommended that chaff that is fed as a separate cow feed from straw should be tested for TDN (energy) and protein content.

Mature dry pregnant beef cows (early to mid-gestation) with their spring calves removed; require about 52 to 55 per cent TDN and about eight to nine per cent protein to meet body maintenance requirements and body condition of 3.5 (1 –emaciated and 5 –fat) as well as support an early term fetus.

The nutrient profile (#1) of most cereal grain swaths, chaff piles and standing stubble will not solely support the energy, protein, mineral and vitamin requirements (#2) of early and mid-gestation cows in a commercial herd. Therefore, extra energy and other nutrients must be supplemented. The magnitude of this feed supplementation depends on the current cowherd feeding program, gestating cow health and body condition as well as pending cold weather factors.

The window of opportunity of feeding most cereal crop residues with extra supplementation is about 60 to 80 days. Beef cows entering the last trimester of pregnancy have a dramatic rise in all nutrient requirements that might be best met with fair-to medium-quality forages such as good quality grass or alfalfa-grass mixtures in favour of lower quality crop residues.

Crop residue feed quality left and fed on the field as straw/chaff piles tend to decline as the winter season progresses (re: natural breakdown of crop residue, accelerated by inclement wet weather) and thus could initiate a subtle decline in cow performance (i. e.: body condition score). In contrast, straw/chaff round bales are quite resistant to inclement environmental conditions, if bales are left and fed intact to cattle.

With a similar several-point protocol in place, the Western Beef Development Centre in a two-year study showed in the first year of feeding trials (2007-08) that 48 Angus gestating beef cows grazed barley straw/chaff piles for 46 days from mid-November to the beginning of January had gained weight and body condition when supplemented with 100 per cent dried distillers grains (DDGS) or 50 per cent DDGS and 50 per cent rolled barley treatments. Extra medium-quality hay was also fed on the straw/chaff piles in order to compensate for very cold weather of the first winter. The performance data demonstrated that crop residues can be effectively utilized in beef cow overwintering rations as long as they are nutritionally balanced with supplemental feeds, so pregnant cows can meet their respective nutrient requirements.

Their feed costs associated with supplemented crop residues were basically cheaper than more conventional forages, but this should not be ground-breaking news to most of us. In a typical western Canadian scenario, if we were to compare the basic feed cost of chaff piles to feeding baled straw for a 500-cow operation for 80 days, we could realize about a $9,000 savings:

500 cows x 9 kg of roughage x $25 tonne feed saving ($5 -$30/ mt) x 80 days = $9,000.

Our assumptions would be: chaff piles or competing straw is our only available forage sources, 600 kg cows consume about 1.5 per cent of their body weight or nine kilograms of these low quality roughages, chaff piles and straw are nutritionally similar and require similar energy, protein and mineral/vitamin supplementation, there is an inherent cost of chaff and field stubble of $5/tonne (re: could be worked into the soil to promote future crop yields), and finally, replacement cost (not production cost) of round-baled straw is estimated at $30/tonne.

Another more in-depth way of reviewing potential feed savings of crop residues is to calculate beef cow day-to-day feed costs using crop residues in their actual diets. The following examples are three balanced beef gestation diets, the first of which implements chaff piles as the sole forage source:

1.9 kg of Chaff @ $5/mt, 3 kg 14 per cent med-energy cow [email protected]$ 140/mt, and 2 oz. of 2:1 cattle mineral w/salt @ $25/25 kg= $0.55/head/day.

2.9 kg of straw @ $30/mt, 3 kg 14 per cent med-energy cow [email protected]$140/mt, and 2 oz. of 2:1 cattle mineral w/salt @ $25/25 kg = $0.78/head/day.

3.12 kg of medium-quality [email protected]$65/mt and 3 oz. of 2:1 cattle mineral w/salt @ $25/25kg = $0.87/head/day.

As illustrated, the feed savings feeding crop residues can be considerable, but before you consider selling your current hay and straw baling machines and visualize your cows grazing chaff piles, you might want to consider the costs of set up of making chaff piles in the field during harvest and letting your cattle out to graze them.

To go out and purchase a chaff box can cost from a couple of thousand dollars to a chaff blower and open-bottom wagon that can run into tens of thousands of dollars. Some additional investment might be required to put in new water lines and waterers as well as put up new fences, so beef cows can effectively utilize chaff pastures. Granted, such capital costs can be spread over several years, but there still should be an overall improved rate of return due to crop residue feeding compare to what is currently done now with conventional feeds.

Aside from some real savings on winter feed costs, one of the main advantages of feeding crop residues to beef cows is that it is already accessible and available feed for most producers that raise cereal and other cash crops. It’s simply a by-product of grain farming and doesn’t have to be purchased or brought in from an off-farm location. As long as it is properly collected and its nutrition is balanced with the required supplementation, crop residues can be economically worked into most early to mid-gestation beef cow feeding programs.

PeterVittiisanindependentlivestock nutritionistandconsultantbasedinWinnipeg. Toreachhimcall204-254-7497orbyemailat [email protected]

About the author

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Peter Vitti is an independent livestock nutritionist and consultant based in Winnipeg. To reach him call 204-254-7497 or by email at [email protected]

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