Introduction

Due to the increasing cost of feed ingredients, producers have increasingly adopted alternative feedstuffs, including fat sources and dried distillers’ grains with solubles (DDGS). In response to these challenges, the swine industry has developed leaner pig genotypes, often through the supplementation of diets with unsaturated fat sources, which results in a higher proportion of polyunsaturated fatty acids in pork. However, elevated levels of unsaturated fatty acids are associated with increased lipid oxidation and compromised belly quality. Dietary supplementation with vitamin E has been reported to mitigate lipid oxidation in pork. Therefore, the objective of this study was to evaluate the effects of dietary fat source (cornstarch, tallow, corn oil, and coconut oil) and vitamin E supplementation (11 and 200 IU/kg) on bacon quality in pigs slaughtered at a heavy body weight (150 kg).

Materials and methods

A total of 64 individually fed pigs were blocked by body weight and sex and randomly assigned to one of eight dietary treatments arranged in a 4 × 2 factorial design. Fat treatments consisted of cornstarch (CS), tallow (TW), corn oil (CO), and coconut oil (CN), while vitamin E (VE) supplementation was provided at 11 or 200 IU/kg. Pigs were humanely slaughtered at approximately 150 kg live weight at the University of Kentucky Meat Laboratory under USDA inspection, in accordance with protocols approved by the Institutional Animal Care and Use Committee of the University of Kentucky. Bellies (IMPS #408) were removed at harvest, weighed individually, and divided into six sections for bacon processing. Measurements of belly depth, belly flex, and belly angle were subsequently obtained. Data was analyzed using SAS by least squares analysis of variance with the generalized linear model (GLM) as a randomized complete block design, with the individual pig serving as the experimental unit. Statistical significance was declared at P ≤ 0.05, and trends were identified at P ≤ 0.10.

Results

Belly depth and belly flex were significantly influenced by dietary fat source (P < 0.01) but were not affected by dietary VE supplementation (P > 0.01). Pigs fed the CO diet exhibited the lowest lateral distance (P < 0.01), the greatest vertical distance (P < 0.01), and the smallest belly angle (P < 0.01), resulting in the softest bellies. In contrast, pigs fed CN had the greatest lateral distance (P < 0.01), the lowest vertical distance (P < 0.01), and the largest belly angle (P < 0.01) compared with the other dietary treatments, resulting in the firmest bellies.

Conclusions

These findings demonstrate the importance of dietary fat sources in determining belly characteristics and bacon quality in pigs slaughtered at heavy body weights (150 kg). Dietary fat sources with a higher proportion of saturated fatty acids improved belly firmness and overall bacon quality compared with fat sources containing greater concentrations of polyunsaturated fatty acids.

Ana Paula Salim, Marlee Kelley, Ding Wang, Surendranath P. Suman, Merlin Lindemann and Gregg Rentfrow are with the University of Kentucky, Department of Animal and Food Sciences. E-mail: mailto:apaulasalim@uky.edu

Acknowledgments

This work was supported by the National Pork Board, Fats and Proteins Research Foundation, and DSM.