Brent Jones from South West Ontario Veterinary Services, How Long Before Marketing Should We Reduce DDGS in Finishing Diets?

In most supply chains there is a recognition that the system as a whole needs to be optimized. Having said that, there are still some competing interests between partners and therefore a need to find a balance of those interests. Feeding diets high in corn distillers dried grains with solubles (DDGS) before market can help to reduce the cost of production for producers. The old addage of “You are what you eat.” was never more true with respect to the pig’s consumption of DDGS in the finishing diet. If pigs eat more polyunsaturated fats their own body fat will also contain more polyunsaturated fats. This makes the fat softer which in turn makes it more difficult to process and less desirable for the consumer. Belly fat iodine value (IV) is used to objectively measure the softness of fat in the carcass. DDGS are high in neutral detergent fiber (NDF), and thus may negatively affect carcass yield and hot carcass weights (Coble et al., 2017).

Researchers at Kansas State University along with producer and processor partners wanted to evaluate the effects of switching from DDGS-based to corn-soybean meal (CSBM)-based diets at various intervals (withdrawal periods) before harvest on finishing pig performance and carcass characteristics. Diets in both experiments contained either 0% or 30% DDGS and were balanced for net energy (NE).

In Exp. 1, 985 pigs at 99.6 kg body weight [BW]) were used with 12 pens per treatment. The four treatments were increasing DDGS withdrawal periods: 28, 21, 14, or 0 d (no dietary switch) before marketing. All pens were marketed by removing the 17% heaviest pigs 21 days before slaughter and the remaining 83% all slaughtered 21 d later.

  • There was no evidence for treatment differences on final BW, average daily feed intake, or feed efficiency (G:F; P > 0.10);
  • Average daily gain (ADG) increased (linear, P = 0.022) and belly fat IV decreased (linear, P = 0.001) the longer pigs were fed CSBM diets.
  • There was no evidence for differences for Hot Carcass Weight  (P > 0.10);
  • Carcass yield increased (linear, P = 0.001) with increasing time following the switch to CSBM.
  • Backfat depth decreased and percentage lean increased as CSBM feeding time increased (quadratic; P < 0.05).

In Exp. 2, 1,158 pigs at 105 kg BW were used in a 35-d study. There were 15 pens per treatment and four treatments of increasing DDGS withdrawal periods: 35, 28, 14, or 0 days (no dietary switch). All pens were marketed by removing the 15% heaviest pigs on day 28, the 28% heaviest pigs on day 14, and a final marketing of approximately 57% of starting barn inventory.

  • There was no evidence that final BW, ADG, G:F, or Hot Carcass Weight  differed among dietary treatments (P > 0.10).
  • Average daily feed intake and carcass yield increased and belly fat IV decreased (P < 0.050); the longer pigs were fed CSBM.

Take Home Message:

  • There was minimal impact on growth performance following a premarketing switch from Distillers Dried Grains with Solubles to Corn Soy Bean Meal based diets when dietary NE was kept approximately constant. This lowered the economic impact on the producer when making the switch.
  • For carcass yield and belly fat IV, the optimal time to make a dietary switch from high to low fiber appears to be linear in nature and at least 28 days before marketing.

Submitted by Dr. Brent Jones

Ref:   Annie B Lerner , Mike D Tokach , Joel M DeRouchey, Steve S Dritz , Robert D Goodband , Jason C Woodworth , Chad W Hastad , Kyle F Coble , Emily Arkfeld , Hilda C Cartagena , Christopher Vahl   Effects of corn distillers dried grains with solubles in finishing diets on pig growth performance and carcass yield with two different marketing strategies  Transl Anim Sci . 2020 May 21;4(2):txaa071. doi: 10.1093/tas/txaa071.