Feed represents about 60 to 75% of the total cost of pork production; therefore, a thorough knowledge of the principles of swine nutrition is essential to maintain a profitable swine industry. Feeding higher protein levels has been associated to improvements in carcass composition, with lower intramuscular fat content and less-tender meat. Therefore, the aim of the present study was to determine how varying levels of protein, lysine, fat, and fiber in swine diets affected swine growth and pork quality. For that purpose, a total of 12 crossbred barrows (≈4 months of age and 63.5 kg) were selected and were randomly allotted into two groups: a commercial pig feed (protein min 14%, lysine min 0.69%, fat min 6.8%, fiber max 8.7%) and a show pig feed (protein min 22%, lysine min 1.55%, fat min 1.80%, fiber max 2.6%). Pigs were fed with experimental diets for 56 days. Body weight (BW) was recorded weekly. Hot carcass weight, NPPC color, NPPC firmness, NPPC marbling, loin eye area, tenth and last rib fat thickness were measured. Dressing percentage and percent fat free lean were calculated.
As a result, there were minimal differences between diets related to weekly weights and pork quality. However, the show diet had a higher ADG for week 1 (1.21 kg vs. 0.76 kg). This is most likely due to compensatory gain from switching types of hog feed. Barrows fed the show feed had a higher dressing percentage (74.7 vs. 71.0%) and more fat at the last rib (2.79 cm vs. 2.03 cm). Additionally, the show feed resulted in higher L* values in the loin eye, yet no visual color differences were observed with NPPC Color. There was a trend for the barrows fed the show feed to have larger muscle scores and larger loin eye areas. All other measurements and calculations were not significantly different. However, show fed barrows resulted in observationally firmer fat than commercial fed barrows.
These results suggest that diets higher in protein and lysine and lower in fat and fiber lead to a higher dressing percentage and seemingly lighter in color. Therefore, carcasses should give higher economic return.
Price, H., Williamson, S., Henson, J., and Mc Keith, A. G. (2019). Effects of various levels of protein, lysine, fat, and fiber on swine growth and pork quality. Meat and Muscle Biology, 1(3), 157-157. https://doi.org/10.221751/rmc2017.152