Physical Corn Kernel Attributes Influence on Beef Cattle Performance

• Specific physical characteristics of corn kernels can be used to predict feed efficiency in beef cattle.
• Studies found that high test weight was not a good indicator of beef feed-to-gain, although kernel size and kernel softness were highly correlated.
• In a dry-rolled, corn-based diet, cattle fed corn with a higher proportion of soft gain more endosperm efficiently than cattle fed corn with a hard endosperm.

Introduction

Kernel characteristics such as test weight, density and hardness can vary significantly between corn hybrids. Test weight, expressed as lbs/bu, can often become part of seed selection discussions even though grain market prices are typically not discounted until test weight falls below U.S. No. 2 Yellow corn standards of 54 lbs/bu. It is widely believed that high test weight grain is associated with high grain yields and feeding performance, however there is little evidence in research literature to support this.

In collaboration with the University of Nebraska-Lincoln (UNL), the Golden Harvest^® agronomy team designed trials to evaluate the role that physical characteristics of corn kernels have on beef cattle feed performance.1 Trials were designed in a way to address 2 main research questions:

1. Is cattle feed performance affected by physical attributes of corn hybrid grain utilized in feed rations?
2. Which corn kernel characteristics most influence feed performance?

Beef Feedlot Study Design

• 8 crossbred steer calves were randomly assigned to pens.
• 7 hybrids with differing kernel characteristics were grown, characterized for kernel attributes, and assigned to an individual pen as part of the feed ration.
• Rations consisted of 66% dry-rolled corn of each selected hybrid with 20% wet gluten, 10% corn silage and 4% supplement.
• Each hybrid was replicated in 4 pens.
• Cattle were fed for 167 days and processed at a commercial packing plant.
• Carcass data was collected to calculate multiple beef performance and quality variables.

Kernel Characteristics Measured

1. Test weight
2. 1,000 kernel weight
3. Kernel size and shape
4. Feed constituent content (% protein, oil, starch, etc.)
5. Starch type
6. In-vitro starch disappearance
7. In-situ rate and extent of disappearance
8. Kernel hardness (as determined by various methods)

Feedlot Study Results

Graph 1. Feed-to-gain ratio of each hybrid

Of all animal performance variables measured, “feed-to-gain ratio” was the only feed performance characteristic influenced by hybrid grain characteristics (Chart 1). Feed-to-gain is the average pounds of feed needed for each pound of animal gain. Low feed-to-gain values indicate that less feed is needed to produce similar weight gain. Other animal performance variables such as dry matter intake, average daily gain, hot carcass weight, marble score and 12th rib fat were not influenced by hybrid differences. In a dry-rolled, corn-based diet, cattle fed corn hybrids with a higher proportion of soft endosperm tended to gain more efficiently than cattle fed corn hybrids with a harder endosperm.

Grain Characteristics Related to Low Feed-to-Gain Ratio

Of the 8 kernel characteristics measured across hybrids, 1,000 kernel weight, kernel hardness and in-situ rate of disappearance were strongly correlated with better, lower feed-to-gain ratios. More commonly recognized attributes such as high test weight were not as correlated to feed efficiency gains. Due to the high correlations and relative ease of being able to characterize hybrids for 1,000 kernel weight and hardness characteristics, Golden Harvest utilizes these findings to characterize commercial hybrid physical grain characteristics for determining which are more likely to have better feed performance.

Table 1. Hybrid 1,000 kernel weight and Stenvert Hardness test results

1. 1,000 kernel weight
   • Closely related to kernel size
   • Different measurement than test weight
   • Higher values correlated to better (lower) feed-to-gain ratios (r² = -0.8135; P = 0.026)
2. Kernel hardness
   • The “Stenvert Hardness Test” provided the best predictors of feed-to-gain response
   • Softer kernels have better feed-to-gain ratios
   • Hybrids that required less time to grind in a micro-hammer mill (r² = 0.8275; P = 0.022) and produced a larger percentage of soft particles (r² = -0.83202; P = 0.021) resulted in improved feed performance (lower feed-to-gain ratio)
3. In-situ rate of disappearance
   • Percent of grain digested within live animal rumen over designated time

Chart 1. Feed-to-gain ratings

References:

¹ Jaeger, S.L. M.K. Luebbe, C.N. Macken, G.E. Erickson, T.J. Klopfenstein, W.A. Fithian, and D.S. Jackson. 2006. Influence of corn hybrid traits on digestibility and the efficiency of gain in feedlot cattle. Journal of Animal Science. 84(7): 1790-1800.

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