A total of 288 pigs (PIC 327 × 1050, initially 109.3lb bodyweight) were used in an 81-day trial to determine the effects of diet form and fibre (from dried distillers grains with solubles DDGS and wheat middlings) withdrawal before harvest on growth performance of growing-finishing pigs.

Treatments were arranged in a 2×3 factorial with the main effects of diet form and dietary fibre feeding regimen. The two diet forms were meal or pellet. The three fibre feeding regimens were:

1. low dietary fibre (corn-soybean meal–based diets) from day 0 to 81
2. high dietary fibre (30 per cent DDGS and 19 per cent wheat middlings) from day 0 to 64, followed by low fibre from day 64 to 81 (fibre withdrawal), and
3. high dietary fibre from day 0 to 81.

No interactions (P>0.13) were observed for growth performance between diet form and fibre withdrawal regimens.

From day 0 to 64, there were no differences (P>0.27) in average daily gain between pigs fed different diet forms. Pigs fed meal diets had increased (P<0.02) average daily feed intake and poorer (P<0.001) feed:gain ratio compared with pigs fed pelleted diets. Pigs fed pelleted diets tended (P<0.08) to have increased final bodyweight and hot carcass weight than pigs fed meal diets but no difference (P>0.28) was detected in carcass yield.

From day 0 to 64, fibre level did not influence average daily gain (P>0.64). However, pigs fed low-fibre diets had decreased (P"0.01) average daily feed intake and improved (P<0.001) feed:gain ratio compared with pigs fed high-fibre diets.

From day 64 to 81, pigs fed pelleted diets had increased P<0.005) average daily gain and tended to have increased (P<0.10) average daily feed intake and better feed:gain ratio (P<0.06) than pigs fed meal diets.

Pigs on the fibre withdrawal regimen had increased (P<0.03) average daily gain compared with pigs kept on high-fibre diets; pigs previously fed the low-fibre diet were intermediate. Withdrawal of the high-fibre diet resulted in an increase (P<0.001) in average daily feed intake compared with pigs fed low-fibre or high-fibre diets throughout.

Pigs fed low-fibre diets throughout the trial had a better (P<0.02) feed:gain ratio than pigs fed high-fibre diets throughout, and pigs on the withdrawal regimen were intermediate.

Overall (day 0 to 81), pigs fed pelleted diets had higher (P<0.03) average daily gain and better (P<0.001) feed:gain ratio than pigs fed meal, with no difference (P>0.12) in average daily feed intake.

Fibre regimen did not influence (P>0.35) average daily gain for the overall trial. However, pigs fed low fibre throughout the trial had lower (P<0.001) average daily feed intake and better (P<0.001) feed:gain ratio than pigs fed the withdrawal regimen or pigs fed high fibre throughout.

Fibre regimen did not affect (P>0.11) final bodyweight or hot carcass weight but the fibre withdrawal regimen restored carcass yield to the low-fibre pigs, both of which were greater than those fed the high-fibre regimen (P<0.001).

For carcass fat quality, pigs fed pelleted diets had high (P<0.001) belly fat iodine value than pigs fed meal diets. Compared with pigs fed high fibre throughout the trial, pigs fed the low-fibre regimen had lower (P<0.001) iodine value, with those fed the withdrawal regimen intermediate.

Compared with pigs fed low-fibre diets throughout, feeding high-fibre diets increased average daily feed intake and resulted in poorer feed:gain ratio, regardless of withdrawal.

Withdrawing fibre allowed pigs to recover fully from losses in carcass yield but only an intermediate improvement in belly fat iodine value was observed.

Pelleting the diets improved average daily gain and feed:gain ratio, but worsened belly fat iodine value, regardless of diet formulation. However, pelleting increased belly fat iodine value to a greater extent with the high-fibre diet containing DDGS and wheat middlings than with the low fibre, corn-soybean meal diet.

Nemechek and co-authors summarised their findings by saying that pelleting the diets improved average daily gain and feed:gain ratio but for unknown reasons, increased the amount of unsaturated fatty acids in the belly, resulting in higher iodine value than pigs fed meal diets. This increase in belly fat iodine value was greater when the high-fibre diets were fed than when the corn-soybean meal diet was fed but due to the higher level of unsaturated fatty acids in the high-fibre ingredients used. Compared with pigs fed low-fibre diets throughout, feeding high-fibre diets increased average daily feed intake and resulted in poorer feed:gain ratio, regardless of withdrawal.

They added that, consistent with previous research, high-fibre withdrawal allowed pigs to recover fully the losses in carcass yield associated with feeding high fibre levels but only an intermediate improvement in belly fat IV was observed.

Reference

Nemechek J.E., M.D. Tokach, S.S. Dritz, R.D. Goodband, J.M. DeRouchey and J.L. Nelssen. 2012. Effects of diet form and fibre withdrawal before marketing on growth performance of growing-finishing Pigs. Proceedings of the Kansas State University Swine Industry Day 2012, p265-277.

Further Reading You can view the full paper in the proceedings by clicking here. Other papers presented at this conference can be viewed by clicking here.

January 2013