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Effect of Feed Form (Mash vs. Pellets) and Ractopamine on Pork Fat Quality
A trial was conducted in a commercial production system to compare fat quality of PIC337 x C29 pigs fed equivalent diets in the form of either mash or pellets. Seven days prior to the first marketing, pigs were allocated to either control or ractopamine (5 ppm; RAC) diets. Thus, the treatments were a 2 x 2 factorial arrangement. Experimental units were pen for growth data and pig for fat quality data. A total of 1,200 pigs were placed in a wean-finish barn and sorted by sex and randomly allotted to treatments (46 pens; 11 or 12 pens per treatment). A standard diet meeting nutrient requirements for pigs from 5.4 to 122 kg live weight was used. Pigs were marketed to a commercial packing facility where belly fat (n = 534; 130 to 137 per treatment) and clear plate backfat (BF; n = 1025; 246 to 264 per treatment) samples were collected and analyzed using near-infrared spectroscopy. No feed form x RAC interactions were observed (P > 0.05). Pelleting (4.9%) and RAC (5.4%) improved GF (P < 0.0001), but ADG (P > 0.18) was only numerically higher. Pigs fed pelleted diets had higher belly fat (P < 0.0001) C18:2 (14.9 vs. 16.5), C18:3 (0.62 vs. 0.72), and IV levels (69.2 vs. 71.6), but lower (P < 0.005) C16:0 (23.3 vs. 22.7), C16:1 (2.91 vs. 2.80), C18:0 (9.1 vs. 8.9) and C18:1 (45.3 vs. 44.3) levels. Pigs fed pelleted diets had higher BF (P < 0.0001) C18:2 (15.1 vs. 17.1), C18:3 (0.75 vs. 0.87), and IV levels (69.1 vs. 72.3), but lower (P<0.0001) C16:0 (23.5 vs. 22.7), C16:1 (2.21 vs. 2.11), C18:0 (9.8 vs. 9.5) and C18:1 (43.8 vs. 42.9) levels. Pigs fed RAC had higher belly fat (P < 0.01) C18:2 (15.3 vs. 16.1), C18:3 (0.66 vs. 0.69), and IV levels (69.8 vs. 71.0), but lower (P < 0.01) C16:0 (23.1 vs. 22.8), C18:0 (9.1 vs. 8.9) and C18:1 (45.0 vs. 44.7) levels. Pigs fed RAC diets had higher BF fat (P < 0.0001) C18:2 (15.6 vs. 16.6), C18:3 (0.78 vs. 0.84), and IV levels (69.9 vs. 71.5), but lower (P < 0.005) C16:0 (23.3 vs. 22.9), C16:1 (2.18 vs. 2.14), C18:0 (9.8 vs. 9.6) and C18:1 (43.6 vs. 43.1) levels. These data indicate that while pelleting and RAC both have positive effects on growth, they could have negative effects on fat quality.
Keywords:
pigs, pelleting, ractopamine, fat quality