Effects of lowering dietary fiber before marketing on finishing pig growth performance, carcass characteristics, carcass fat quality, and intestinal weights1,2

Abstract

A total of 264 pigs (initially 41.0 kg BW) were used in a 90-d study to determine the effects of lowering dietary fiber before market on pigs fed high dietary fiber [provided by wheat middlings (midds) and distillers dried grains with solubles (DDGS)] on growth performance, carcass characteristics, carcass fat quality, and intestinal weights of growing-finishing pigs. Pens of pigs were randomly allotted by initial BW and sex to 1 of 6 treatments with 6 replications per treatment and 7 or 8 pigs per pen. A positive control (corn-soybean meal-based) diet containing no DDGS or midds (9.3% NDF) and a negative control diet with 30% DDGS and 19% midds (19% NDF) were fed throughout the entire trial (d 0 to 90). The other 4 treatments were arranged in a 2 × 2 factorial with the main effects of length of fiber reduction (23 or 47 d before marketing) and fiber level fed during the reduction period (low or medium). Pigs on these treatments were fed the negative control before the reduction treatment. The medium-fiber diet contained 15% DDGS and 9.5% midds (14.2% NDF) with the low-fiber diet was the positive control diet. Increasing the feeding duration of the low-fiber diets lowered overall ADFI (linear, P = 0.03) and improved G:F (linear, P < 0.01). Lowering the fiber level for the last 23 d did not influence growth performance; however, lowering the fiber level improved carcass yield (P = 0.002), with a greater response (P < 0.001) when the low-fiber diet was fed for 23 d. Jowl fat iodine value (IV) decreased when the longer lower fiber diets were fed (linear, P < 0.01) and was lower (P < 0.001) for pigs fed the low-fiber diet during the fiber reduction period than pigs fed the medium-fiber diet during the same time period; however, increasing the time lower fiber diets were fed from 23 to 47 d further reduced (P < 0.01) jowl IV. Increasing the duration that the control diet was fed by increasing the reduction time from 23 to 47 d increased (P < 0.01) backfat depth. Reducing the fiber level decreased full large intestine weight (linear, P = 0.005) with a greater response (P = 0.04) when the low-fiber diet was fed during the reduction period instead of the medium-fiber diet. In summary, lowering the fiber level before marketing can improve G:F, carcass yield, carcass IV, and reduce large intestine weight; however, the optimal duration of the fiber reduction period depends on the targeted response criteria.

Effects of diet form and type on growth performance, carcass yield, and iodine value of finishing pigs1

“…1, however, withdrawing these ingredients 17 d before market improved carcass yield and returned carcass weights to values similar to those of the control-fed pigs. Asmus et al (2014) also demonstrated that switching pigs from a high-fiber diet to a low-fiber diet 23 d before market allowed for full recovery of carcass yield. In agreement, Coble et al (2014) reported that removing DDGS and midds 15 to 20 d before harvest allowed carcass yield to return to levels of pigs fed corn-soybean meal-based diets throughout the finishing period.…”

“…The diets fed in Exp. 1 were similar to those used by Asmus et al (2014), who investigated the effects of reducing or completely removing DDGS and midds from finishing pig diets for multiple durations. The authors reported similar increases in ADG and ADFI when the high-fiber components were withdrawn from the diet and attributed this effect to the bulk density and energy content of the diets; that is, pigs previously fed high-fiber diets continued to consume higher volumetric amounts of feed despite switching to a more energy-dense diet.…”

“…Fat samples were thawed, and adipose tissue was isolated by removing the skin and lean tissue. Samples were then analyzed for FA profiles using gas chromatography as described in detail by Asmus et al (2014). Iodine value was calculated using the following equation (American Oil Chemists' Society, 1998) …”

“…This is due to increased large intestinal weights caused by the high-fiber component of the ingredients (Asmus et al, 2014). Along with the dietary fiber component from DDGS and midds, the oil content, particularly C18:2 fatty acids, also increases (NRC, 2012).…”

“…Feeding ingredients high in UFA increases carcass fat IV (Benz et al, 2011), thus producing less desirable product for the meat packing industry (McClelland et al, 2012). Reducing or withdrawing added DDGS and midds before marketing can mitigate some of the negative effects on carcass yield and carcass fat IV (Gaines et al, 2007;Asmus et al, 2014;Coble et al, 2014).…”