Animal Industry Report

Extension Number

ASL R2736



Summary and Implications

The inclusion of unsaturated fats in pig diets has raised issues related to pork carcass lipid quality. The objective of this experiment was to develop a more comprehensive understanding of how dietary fat affects the composition of body fat during the finishing period and at market. A total of 42 gilts and 21 barrows (PIC 337 X C22/29) with an average initial weight of 77.8±3.06 kg were allotted based on sex and weight to 7 treatments: 3 and 6% of each of tallow (TAL; iodine value (IV)=41.9), choice white grease (CWG; IV=66.5) or corn oil (CO; IV=123.1), and a control (CNTR) corn-soy based diet with no added fat. Pigs were individually housed to track dietary fat and energy intake. Pigs were weighed and adipose samples were collected from the jowl, belly, and loin on days 0, 18, and 35 and at harvest. Iodine value was determined on diet and carcass lipid samples. Belly weights were recorded at harvest along with a subjective belly firmness score (1-3 with 1 firmest and 3 least firm) 24 h post-mortem. Data were analyzed using PROC MIXED and PROC CORR. Carcass lipid IV was affected by source (TAL=66.8, CWG=70.3, CO=76.3, CNTR=65.4; P<0.0001). Carcass lipid IV for TAL and CWG was not affected by inclusion level; however, CO was affected by level (3%=72.6, 6%=80.0; P<0.0001). Carcass lipid IV was also affected by sex (barrows=69.1, gilts=71.5; P<0.001). The correlation between carcass lipid IV and dietary lipid IV was R2=0.592. Belly weight was increased by inclusion level (CNRT=8.3 kg, 3%=8.8 kg, 6%=9.4 kg; P<=0.02). Belly firmness score was affected by source (CNTR=1.8, TAL=1.7, CWG=2.0, CO=2.2; P<0.05) and sex (barrows=1.6, gilts=2.3; P<0.0001). ADG was increased by inclusion level (CNTR=0.93 kg, 3%=1.04 kg, 6%=1.10 kg; P<0.02). G:F was also improved by inclusion level (CNTR=0.301, 3%=0.337, 6%=0.358; P<0.01). In conclusion, an increase of dietary fat can improve feed efficiency and performance. Dietary fat sources that are highly unsaturated will increase carcass fat IV in a dose dependent manner.

Copyright Holder

Iowa State University