This project speaks directly to the primary objectives of the Improving Fat Quality program, by seeking to maximize production efficiencies through optimizing the use of dietary fat and cost-effective ingredients to maximize economic goals for the producer while still achieving a desirable final carcass quality product. There appears to be a growing negativity regarding the use of unsaturated dietary fat. Producers need to achieve economic targets so the use of ingredients that are cost-effective is a must, while the packing sector sees increased problems with “soft fat” in the carcass. Neither goal (performance versus carcass) can be addressed in isolation of the other. Performance targets must consider final carcass quality, but at the same time, carcass quality must be considered in the context of pig performance in the barn. Alternative ingredients, such as conventional distillers grains, contain high levels of fat; optimizing the use of such products requires a thorough understanding of the impact of the fat component on carcass quality as well as on performance. Other alternative ingredients, such as high protein distillers’ grains, require the use of added dietary fat to boost energy to levels that achieve pig growth targets. Again, optimum use of such ingredients requires a thorough understanding of the impact of the added fat on carcass quality as well as on pig performance. The outstanding question is how much fat can be added to the diet and for how long must the fat be removed from the diet prior to harvest, while maintaining minimum standards for carcass quality.

Fifty individually housed pigs were allotted based on sex and initial BW to 10 treatments for an 82 d experiment: 3 dietary fat withdrawal times prior to slaughter (21, 42 or 63d) by 3 dietary fat sources (5% animal-vegetable blend, 2.5% corn oil, or 5% corn oil), plus a control diet with no added fat. Pigs were weighed and jowl adipose samples were collected on days 0, 21, 42, 63 and at harvest on d82.

This study found that if the consumption of PUFAs is relatively low prior to the withdrawal of the unsaturated ingredient, the withdrawal technique will successfully lower carcass IV in a rapid and significant fashion. High amounts of 18:2 consumption via the addition of 5% CO showed that an elevated load of dietary unsaturated fat intake makes lowering carcass IV and diluting 18:2 from the depot very difficult and may take as long as 61d. The withdrawal of unsaturated dietary fat sources from the diet allowed the pig to produce fat metabolically, which results in a firmer, more saturated fat. However, contrary to our expectation, this change in diet did not result in the improvement of belly firmness, depth, weight, or fat color.