Gender

Because the weight gained in gilts has a higher lean-to-fat ratio, less feed is required for each pound of weight gain in gilts compared to barrows. Although the exact difference varies by genetic line, gilts typically are 3 to 6% more feed efficient in the finishing period than barrows. Similarly, boars are more efficient to feed than gilts.

Productivity

When examining whole herd feed efficiency, the productivity of the sow herd directly determines the number of pigs that sow feed use and costs can be spread over. As an example, let's consider two identical farms that use 2,100 lb. of feed per sow per year. If one of the farms markets 18 pigs/sow/year, each pig marketed would carry the cost of 117 lb. of sow feed. If the other farm marketed 22 pigs/sow/year, each pig marketed would carry only 95 lb. of sow feed.

Weight range

Because feed efficiency becomes poorer as pigs become heavier, the starting and ending weight of pigs must be considered when comparing closeout feed efficiency from one group or farm to another.

For example, feed efficiency increases by approximately 0.005 lb. for each 1-lb. increase in average starting and ending weights for the group. Thus, if two groups of pigs have the same starting weight, but one is marketed 10 lb. heavier than the other group, feed efficiency would be expected to be 0.05 higher for the heavier group, just because of the market weight. On an energy basis, the 0.005 lb. would be equivalent to 7.5 kcal more metabolizable energy for each 1-lb. increase in average starting or ending weight.

Weaning age

Although weaning age doesn't have much impact on feed efficiency, it can greatly impact other measures of efficiency of feed use, such as feed cost in the nursery, because lower complexity (and lower cost) diets are required as weaning age is increased.

Benchmarking Efficiency of Feed Use

Because so many factors influence feed efficiency, the best benchmarks are those developed within the production system. The overall goal of benchmarking is to make consistent, measurable improvement over time.

When comparing benchmark levels, adjustments must be made to account for the factors that influence feed efficiency, such as gender, diet form, dietary energy level and starting and ending weight, as discussed above.

The values provided in Table 1 offer intervention levels for closeout feed efficiency for nursery, finishing and wean-to-finish pigs. If the efficiency numbers for the production system are not better than these levels, reasons for this deficiency should be investigated.