Corn gluten feed is a byproduct of corn wet-milling that is available throughout the country. It is utilized in the wet form near the site of production, or it is dried to improve storability and reduce freight charges when shipped. In North Carolina, dry corn gluten is available to smaller producers from a variety of sources, and the price is usually 60 to 70% of its value calculated from the energy and protein levels.
Despite good "book values" for nutrient content, corn gluten feed has been disappointing as a substitute for corn and soybean meal in several previous trials when used as a high percentage of the corn silage or sorghum silage-based diets for growing calves. The trial reported here explored using dry corn gluten feed as an alternative supplement to orchardgrass hay for wintering steer calves.
Materials and Methods
The trial was conducted at the Upper Mountain Research Station in Laurel Springs, NC. Thirty spring-born Angus x Simmental steer calves (average initial weight 499 lbs) were allotted from within weight groups to six pens with two pens per treatment. The calves had been born at the research site and were processed using a standard weaning program before starting the trial.
Calves were fed orchardgrass hay (11.8% crude protein, 33.5% ADF, .38% Ca and .35% P) and a high calcium mineral supplement (18.8% Ca, 4.16% P) free choice. Calves received either #1) 6 lbs per head per day of a standard corn and soybean meal supplement (13.6% crude protein, 3.2% ADF, .2% Ca and .35% P), #2) 3 lbs per head per day of the standard supplement and 3 lbs per head per day of dried corn gluten feed (23% CP, 11.5% ADF, .02% Ca and 1.16% P) or #3) 6 lbs per head per day of corn gluten feed. The corn gluten feed was obtained from a major corn processor and the corn and soybean meal mix was obtained from a local feed mill. Prices used in the economic analysis were as follows: Hay, 80 $/ton; corn and soybean meal, 175 $/ton; corn gluten feed, 120 $/ton; mineral supplement, 250 $/ton. Cattle were assumed to be worth $.78/lb initially, and $.70/lb at the end of the trial.
Shrunk weights were taken at the beginning and end of the 91-day trial. During the 9th week of the trial, samples of rumen fluid were obtained two hours after feeding using a stomach tube to evaluate ruminal volatile fatty acid proportions and ruminal ammonia.
Results and Discussion
Results of the trial are shown in Table 1. As the level of corn gluten feed increased in the diets, the growth rate of the calves declined and feed efficiency was reduced. Neither hay or dry matter intake was changed. When intake of both the hay and supplement were combined, the calculated protein level for the three diets was 12.4, 13.9 and 15.6%, and calculated TDN content was 72.2, 71.9 and 71.7%, for diet 1, 2, and 3 respectively.
There maybe several possible explanations for the reduced performance of the calves. The protein in corn gluten feed has a high level of ruminal degradability, so that it is potentially less valuable that soybean meal. However, the corn gluten feed was used primarily as an energy source, and the protein level was allowed to increase, which would probably offset any reduction in protein quality. It was observed that there were very high levels of ruminal ammonia with both diets supplemented with corn gluten feed. The need to detoxify large amounts of ammonia could have contributed to decreased performance, although the protein levels were not especially high. The current trial was not designed to determine why level of production was reduced; additional experiments will be needed to find strategies to improve performance with this alternative concentrate.
The expected value of the corn gluten feed was the same as the amount we paid for the corn and soybean meal ($175/ton). We actually paid $120/ton, so total feed costs were reduced as the level of corn gluten feed increased. However, due to the decreased sale weights, gross return was reduced, resulting in a lower return over feed cost when level of corn gluten feed was increased. By setting the return over feed cost of diets containing corn gluten feed to the same level observed for the standard supplement a breakeven price for the corn gluten feed was determined. Under the conditions of this trial, the dry corn gluten feed was worth $89/ton.
The Bottom Line
Dried corn gluten feed was explored as an alternative to corn and soybean meal for supplementing growing steers fed orchardgrass hay. Gain was reduced as corn gluten feed was substituted for the standard supplement, reducing return over feed cost given the prices paid for the two supplements. Additional work needs to be done with dried corn gluten feed before it can be recommended to producers given current market prices.
|Table 1. Influence of level of corn gluten feed on the performance of and economic return from steers fed orchardgrass hay-based diets.|
|# 1||# 2||# 3||Linear||Quadratic|
|Initial weight, lb||497.7||498.5||499.8||NS||NS|
|Final weight, lb||747.4||736.8||718.2||.08||NS|
|Average daily gain, lb/day||2.74||2.62||2.40||.02||NS|
|Hay dry matter intake, lb/day||11.4||11.6||11.4||NS||NS|
|Dry matter intake, lb/day||16.7||16.9||16.9||NS||NS|
|Ruminal ammonia, mg/dl||13.4||25.4||26.3||.01||.01|
|Gross return, $/head||134.98||127.02||112.93||.02||NS|
|Feed cost, $/head||94.95||88.69||81.19||.02||NS|
|Return over feed cost, $/head||40.30||38.88||31.72||.06||NS|