#07-152

Complete

Date Full Report Received

02/10/2009

Date Abstract Report Received

02/10/2009

Investigation

Institution:
Primary Investigator:

A large collaborative experiment involving 560 crossbred pigs was conducted at nine experiment stations to assess the effects of feeding high levels of corn distillers dried grains with solubles (DDGS) on performance of growing-finishing pigs from 71 to 265 lb body weight and on carcass and belly firmness.

At each station, fortified corn-soybean meal diets containing 0, 15, 30 or 45% DDGS were fed to growing-finishing pigs in three phases. A common source of DDGS analyzing 26.3% crude protein, 0.96% lysine, and 9.7% fat was used at each station. Diets were formulated to contain 0.83, 0.70, and 0.58% true ileal digestible lysine during the three phases with diets changed at 133 and 200 lb, respectively. The DDGS replaced corn and soybean meal, and crystalline lysine and tryptophan were added to maintain constant true ileal digestible levels of the amino acids in each phase. At each station, two pigs from each pen in two replications were killed for carcass and belly flex measurements. A midline backfat core also was obtained for fatty acid analysis and determination of iodine values.

Growth rate over the entire experimental period was reduced slightly in pigs fed the two higher levels of DDGS (2.08, 2.10, 2.04, 2.02 lb/day). This trend was significantly linear (P < 0.03); however, it represents only a 2.9% decrease in growth rate at the highest level of DDGS inclusion. Daily feed intake and efficiency of feed utilization were not significantly affected by DDGS inclusion (6.02, 6.08, 5.90, 5.94 lb/day; 2.90, 2.91, 2.92, 2.96 feed/gain). These data indicate that high levels of DDGS can be fed to growing pigs without having much of an effect on pig performance provided the diets are properly formulated.

Carcass yield (dressing percent) was not affected by level of DDGS fed. Backfat decreased slightly (0.89, 0.89, 0.84, 0.85 in.; linear, P < 0.02) as did loin eye area (but the decrease was not significant; 7.35, 7.34, 7.15, 7.03 in.2) in pigs fed the two higher levels of DDGS. Percent fat-free lean in the carcass was not affected by dietary treatment (51.9, 52.2, 52.4, 52.1%).
Belly flex measurements were significantly (P < 0.001) affected by DDGS level in the diet. Lateral flex measurements decreased linearly (4.67, 3.38, 3.29, 2.61 in.) and vertical flex measurements increased linearly (10.28, 10.77, 11.10, 11.31 in.) with increasing level of DDGS in the diet. Both of these measures indicated that bellies were softer and more flexible as level of DDGS increased in the diet.

There was a significantly linear (P < 0.001) increase in the polyunsaturated fatty acids in the fat extracted from the backfat tissue as level of DDGS was increased in the diet, indicating a softer fat in pigs fed DDGS. The iodine values of the inner layer of backfat increased from 61.6 in the controls to 82.5 in that of pigs fed the highest level of DDGS (linear, (P < 0.001), again reflecting a softer backfat.
In summary, these results show that rather high levels of DDGS (up to 45% DDGS in the diet) can be fed to growing-finishing pigs without having much of an effect on growth performance or carcass leanness. However, these high levels do result in a higher proportion of polyunsaturated fatty acids in the backfat, higher iodine values in the backfat, and softer, more flexible bellies.