Effect of adding minimally refined cottonseed oil or crude glycerol to diets containing 40% distillers dried grains with solubles (DDGS) on carcass fat firmness of growing-finishing pigs

Abstract Text:

High inclusion (> 20%) of DDGS in diets for growing-finishing pigs causes soft fat in pork carcasses. Cottonseed products or crude glycerol may improve fat firmness. Mixed sex pigs (n = 216, average BW = 24 ± 9 kg) were blocked by BW and allotted to 1 of 3 dietary treatments. Experimental diets in a 3-phase feeding program consisted of basal corn-soybean meal-40% DDGS (CON), CON plus 5% minimally refined cottonseed oil (COT), and CON plus 8% crude glycerol for 6 wk before harvest (GLY). Gilts (16/treatment; 48 total) were harvested (BW = 115 ± 8 kg) and bellies were collected for evaluation. Bellies were suspended perpendicularly on a smoke stick and belly flop angle and flex were determined. Belly fat samples were collected and used to determine thiobarbituric acid reactive substances (TBARS) content on d 0 and 7 post-mortem. Subjective fat firmness was determined for cores of belly, jowl, and backfat. Bellies were processed into bacon, and selected bacon slices were evaluated for shatter, shrink, and cooking loss. Because belly thickness tended to differ among treatments, it was used as a covariate for analysis of belly flop angle data. Dietary treatment had no effect on belly flop angle or belly flex measurements. Bacon shrinkage, cooking loss and subjective firmness of backfat were not different than CON for COT or GLY.  On d 7 post-mortem, TBARS concentration was greater for pigs fed COT (1.44 ng/mg fat ± 0.06) than for GLY (1.04 ng/mg fat ± 0.06; P = 0.01), but similar to CON (1.25 ng/mg fat ± 0.06). In conclusion, feeding 40% DDGS supplemented with either COT or GLY did not improve belly fat firmness.

Table 1. Effect of feeding 40% DDGS diets containing minimally refined cottonseed oil or crude glycerol on carcass fat firmness
Item	CON	COT	GLY	SEM	P-value
Belly thickness, cm	2.75x	3.18y	3.01xy	0.13	0.07
Belly flop angle, degrees	6.21	8.57	6.06	0.95	0.16
Lateral belly flex, cm	8.57	9.45	9.12	0.48	0.37
Vertical belly flex, cm	35.40	35.23	35.16	0.52	0.93
Subjective backfat firmness1	3.25ab	2.64a	3.38b	0.19	0.04
Bacon cook shrink, %	13.48xy	11.01x	14.89y	1.22	0.06
Bacon cook loss, %	37.83xy	36.09x	39.72y	1.45	0.07
a,bMeans within a row lacking common superscripts differ (P < 0.05). x,yMeans within a row lacking common superscripts differ (P < 0.10). 1Scores:  1 = soft; 5 = firm.

Keywords: carcass fat, cottonseed oil, crude glycerol