Feeding Value of Low Test Weight Corn for Pigs

Based on current knowledge, corn test weight does not significantly affect pig growth until it drops below 45 lbs/bu. As test weight declines below 45 lbs/bu, digestible energy decreases by 5-6 % and as a result, feed efficiency and growth rate will also suffer (3-10%) because of reduced energy intake. Research has shown that adding 2-3% oil or fat to diets made with very low test weight corn (below 45 lbs/bu) will help improve performance, but it will not return it to the level achieved with normal test weight corn.

Feed companies adjust their product ingredient formulas to compensate in bad years when corn has a lower nutritive value. On farm feed mixers must adjust their own rations to compensate as well.

To deal with low test weight corn, producers should:

  1. Test corn for moisture and protein.
  2. Determine bushel weight of corn at 15% moisture.
  3. Balance rations with the assistance of your feed advisor of nutritionist to account for differences in protein, energy and moisture.
  4. Recalibrate mix mills to compensate for lower bushel weights.

Table 1 provides an estimate of the weight of low grade corn needed to provide the same energy as 1 kg of 56 lbs/bu corn. These guidelines can be used to reformulate rations.

Table 1: Feed weight adjustments for low grade corn.
Bushel Weight (lbs) Kg required to equal 1 kg
56 lbs/bu corn
56
1.000
55
1.004
54
1.009
53
1.013
52
1.017
51
1.022
50
1.026
49
1.030
48
1.035
47
1.039
46
1.044
45
1.049
44
1.053
43
1.058
42
1.063

Source: OMAFRA. Based on analysis of corn samples from 1992 growing season.

Example calculation:

Reformulate mix of 800 kg corn (56 lbs/bu) + 200 kg soybean meal (SBM) with 50 lbs/bu corn.

Calculate amount of corn needed to provide identical amount of energy: 800 kg x 1.026 = 820.8 kg .

Reformulate mix = 820.8 kg corn + 200 kg SBM = 1020.8 kg mix

On a 1000-kg basis, new mix would contain: 820.8/1020.8 x 1000 = 804 kg corn, and 200/1020.8 x 1000 = 196 kg SBM

December 2009 Pork News & Views - Table of Contents


For more information:
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E-mail: ag.info.omafra@ontario.ca