FEEDING VALUE OF LOW
TEST WEIGHT CORN FOR PIGS
By Janice Murphy,
OMAF Swine Nutritionist


With another year of potential low test weight corn, due to delayed development and/or early frost, it is important for growers to realize that the feeding value of low test weight corn remains close to normal, unless test weights drop significantly.
Based on current knowledge, corn test weight does not significantly affect pig growth until it drops below 45 Ibs/bu. As test weight declines below 45 Ibs/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 Ibs/bu), will help improve performance, but it will not return it to the level achieved with normal test weight corn (56 Ibs/bu).

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 to account for differences in protein, energy and moisture.
4. Recalibrate volumetric 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 Ibs/bu corn. These guidelines can be used to reformulate rations.