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November 1, 2016

Corn Stalk Grazing
No Comments / in Loomix / by Loomix

Grazing corn stalks is a common practice and typically one of the most cost effective ways to winter cows. Historically corn stalks have had a predictable feed value and could maintain body conditions (BC) on a bred cow with minimal supplementation. If managed correctly cows can gain BC while grazing stalks, however, over grazing and loss of BC is always a concern. Producers always want to get the most out of a field sometimes at the expense of BC.

Grain, husk and leaves are the most palatable and nutrient dense fractions left in the field. Stalks and cobs are the least palatable and least nutrient dense fractions and cows do a great job of foraging for the grain, husk and leaves when first introduced to a field leaving stalks and cobs for last. Husk and leaves make up about 40% (Wilson et al. 2004) of the dry matter of a stalk field. Therefore, the take 50 leave 50 is a good rule of thumb for grazing stalks. Once 50% of the fodder is removed by the cows what is left will not have the nutrients needed by a cow. Therefore cows must be moved or an increase in supplementation must occur to maintain BC.

Many producers have expressed concerns that corn stalks have a lower feed value today than they have in the past, and many of the corn stalk analysis I have seen seem to agree with that. Not only lower energy but also lower in calcium, magnesium and protein. National Research Council reported values for corn stalks in both their 1984 (this did not include husk) and 2000 publications. Values from the 1984 NRC were 50, 6.6, 0.57, 0.10 and 0.40; values for 2000 were 65.9, 6.5, 0.62, 0.09, and 0.00 (percent TDN, CP, Ca, P and Mg; respectively). Table one contains the analysis from 3 fields of corn stalks analyzed in 2014. It appears that concerns over nutrients decreasing in corn stalks are justified; also stalks seem to be more variable in their nutrient profile. The reduction in energy could be due to breeding plants with more lignin in the stalks making them stronger and less likely to fall and resulting less ear drop as well. Also breeds of corn may have a different ratio of husk and leaves to stalks and cobs. Better harvest equipment leaves less grain in the fields for the cows reducing the energy value of what is in the field. The change in Calcium and Magnesium are a little harder to explain but could be due to breeding or simple mining the soil of these minerals by not replacing them with fertilization. With all of this in mind supplementation has become more important than ever.

In many cases, NRC may over estimate nutrient value of corn stalks which will diminish cow performance. Table 2 demonstrates the gap that would need to be bridged by a supplement for a cow grazing an average of the stalk fields in table 1. To bridge the gap with a 2 lbs/hd/d supplement it would need to be 35% CP, 30% TDN, and 0.31% Phos. In stalk field 1 Ca supplementation would be needed as well. Alliance Liquid Feeds tries to be proactive; when a trend of declining Ca levels in stalks was noticed, Ca was added to bitter formula to help offset this trend. However, Ca levels in liquid supplement have to be limited for a number of reasons. Therefore, if feeding rates are restricted or if the base forage is significantly deficient another source of Ca must be fed. Properly sampling stalk fields for analysis is important part of managing feed resources and avoiding nutrient deficiencies that can cause production losses. If samples are not taken Alliance Liquid Feeds recommends that you assume a worst case scenario and feed additional Ca. Calcium mix with loose salt, alfalfa or a dry mineral with Ca and P are all good options to insure Ca is sufficient in the diet. For more information about supplementing strategies or for help balancing rations please contact Technical services.

Table 1. Corn stalk analysis for winter of 2014 (DM basis)

ItemsStalk Field 1Stalk Field 2Stalk Field 32001 NRC
Crude Protein, %3.85.45.56.5
TDN, %38.058.356.265.9
Calcium, %0.210.340.480.62
Phosphorus, %0.100.110.090.09
Magnesium, %0.080.130.20.00

Table 2. Gap between the requirement and nutrients provided by base forage for a 1300 lbs cow -Last Trimester

ItemsRequirementAverage of StalksDifference
Stalks, lbs DM26
Crude Protein, lbs/hd/d2.01.3-0.7
TDN, lbs/hd/d13.813.2-0.6
Calcium, g/hd/d29.540.110.6
Phosphorus, g/hd/d18.916.1-2.8

NRC. 2000. Nutrient Requirements of Beef Cattle. Seventh Revised Edition. National Academy Press. Washington, DC.

NRC. 1984. Nutrient Requirements of Beef Cattle. Sixth Revised Edition. National Academy Press. Washington, DC.

Wilson, C. B., G. E. Erickson, T. J. Klopfenstein, R. J. Rasby, D. C. Adams, and I. G. Rush. 2004. A review of corn stalk grazing on animal performance and crop yield. Nebraska Beef Cattle Reports 2004:13-15.

March 30, 2016

Does Fly Control Bug You?
No Comments / in Loomix / by Loomix

by Dr.Kelley Neuhold, Loomix Technical Service Specialist

I am a 4th generation SE Colorado rancher, at the age of twelve I took the money I had saved and purchased two bred cows. Those two baldy cows were the start of my current cow herd. From that time forward my dad and I have run cows together and one of the common conversations we have each year is should we feed fly control. Two of our common concerns are does feed thru fly control work and is it cost effective.

We make a common mistake many producers make, which is starting to feed fly control too late. Dad and I don’t start thinking about fly control until we see flies which is about 30 to 60 days too late. Oral fly control should start being fed 30 days before the last hard freeze. In the continental U.S. start dates range from March 1st in the south to May 15th in the north. If a fly population is established prior to feeding fly control it will take 35 days to see a reduction in fly numbers. A pour-on, spray, or rub could be used in those situations to help decrease the adult fly population.
In my experience many producers mistake fly control for fly eradication, thus their disappointment with their control program. Fly eradication is nearly impossible to accomplish and never cost effective. Two hundred flies per animal is the economic threshold, if the fly population exceeds this threshold production and/or economic losses will occur. Table 1 demonstrates this point very well. Campbell (1976) evaluated the effect of fly control (treated cows 15 flies per cow vs untreated cows 469 flies per cow) on steer weaning weights in the sand hills of Nebraska. Under the conditions of this study fly control increase weaning weights 13 lb at $1.60 per pound that would mean an extra $20.80 per steer weaned. They did not report body condition scores of the cows but I would assume similar if not better body condition for the treated cows.

A three year study conducted in Louisiana evaluated the effect of fly control on replacement heifer performance (Table 2). Pregnancy rates were not different between the two groups, however replacement heifers treated for horn flies gained 15 pound more than heifers not treated over the 140 day feeding period. The greatest gains were realized in heifers that remained open. Open heifers treated for flies gained 0.25 lb/hd/d more than open heifers that were not treated for flies. This makes treated heifers 35 lb heavier over 140 feeding period, at $1.37 per pound, those heifers are $48 more valuable at sale time. This helps offset some of the cost associated with developing an open heifer.

Horn flies are the most economically relevant fly to the cattle industry, this is especially true for pasture cattle. Confinement operations may need to control other types of flies as well as horn flies. Face flies can also have an impact on your bottom line through the spread of disease such as pink eye. Houston (2010) estimated that pinkeye cost producers $150 million annually. Make sure the product you use is labeled for the fly or flies that are on your cattle. One benefit of oral fly control is that there is no need to rotate products, once you find one that works for you, you can stay with it.

To have a successful fly season remember these three keys. First start thinking about fly control before you have flies, don’t be like my dad and I. Second remember it is fly control, some flies are acceptable. Realist fly control reduces the population by 75 to 80%. And finally keeping fly population below 200 flies per animal can add pounds to your cattle and dollars to your bottom line.

Table 1. Effect of treating beef cows
for horn flies on steer weaning weights.1

Item

Treated

Untreated

Weaning weight, lb

387a

374b

Horn flies per cow

15

469

1Adapted from Campbell 1976.

2Means with in a row with different superscripts differ
(P < 0.05).

 

 

Table 2. Effect of horn fly treatment
on replacement heifer performance.1

Item

Treated

Untreated

SEM

P<

Initial weight, lb

781

778

5.5

0.71

Final weight, lb

906

891

6.0

0.01

ADG, lb

0.91

0.82

0.022

0.001

Total gain, lb

128

113

3.1

0.001

Pregnancy Rates, %

75

78

2.8

0.46

ADG Bred, lb

0.89

0.83

0.022

0.004

ADG open, lb

0.98

0.73

0.066

0.002

Campbell, J. B. 1976. Effect of Horn Fly Control on Cows as Expressed by Increased Weaning Weights of Calves. Journal of Economic Entomology. 69:711-712(2).
DeRouen, S. M., L. D. Foil, A. J. MacKay, D. E. Franke, D. W. Sanson, and W. E. Wyatt. 2003. Effect of horn fly (Haematobia irritans) control on growth and reproduction of beef heifer. Journal of Economic Entomology. 96:1612-1616.
Huston, C. 2010.Pinkeye in Cattle. (Publication 2608) Extension Service of Mississippi State University.