This report describes a nutrition trial in which broiler chicks were divided into separate, randomly-positioned pens and reared under controlled conditions in which each of four batches was fed on a different diet treatment during the trial, which started on 18th August and ended 14th September. There was a control diet with no DDGS, two further treatments with 15% and 30% DDGS content respectively, and a fourth treatment also with 30% DDGS content but with added amino acid in the formula. The birds and feed consumed were monitored and weighed every third day, keeping records throughout. At the conclusion of the trial those records were used to prove/disprove two hypotheses: 1. That Dried Distillers Grain Solubles (DDGS) can be included in broiler starter diets up to 30% of DM without compromising bird growth or feed conversion efficiency; and 2. That if diets are formulated to the same ME and CP content, that bird performance will be the same. The trial results disproved the first hypothesis, suggesting that a level of DDGS nearer 10% was better, as has previously been indicated by other research. The second hypothesis was also shown to be invalid, although the addition of amino acid to a 30% DDGS diet treatment made a significant positive difference, substantially mitigating its disadvantageous effects.
Report: Dried Distillers Grain Solubles (DDGS)
A recent article (October 2011) entitled “DDG Feed More Valuable Than Traditional Corn, Soybean Rations” reported that according to the U.S. Department of Agriculture (USDA) DDGS is more prevalent in the diets of livestock and poultry than had been realized previously. That article also stated that a metric ton of DDG can typically replace circa 1.22 metric tons of other feed in part because it contains higher concentrations of energy and protein.
However, according to page 5 of an Australian Dept. of Agriculture and Food report by Bonnardeaux (2007), a potentially negative effect of including too high a percentage of DDGS in the animal diet is that of providing an excess of protein, which can result in the subject animals needing to use additional energy, just to degrade and then excrete the superfluous and unnecessary protein. In fact Table 6 (p.6) of that same report, referring to data provided by Shurson (2005), suggests that the maximum DDGS content in the diet for broilers should be 10%. Because an optimized and cost-effective diet for broilers could have a significant effect on broiler production economics, it is important to determine the appropriate percentage of DDGS to be included.
This report describes our research into the results of a nutrition trial using various broiler feed formulations, in order to prove/disprove the hypotheses that:
DDGS levels of up to 30% in broiler starter diets will not compromise bird growth or feed conversion efficiency;
Diets formulated to the same ME and CP content will produce the same bird performance.
Methods and Materials
Outline of the Trial.
The subject birds were fed the test diets for the trial period of 28 days, which was from 18 August to 14 September, and their weight gain, total feed intake and general health and welfare were recorded on the scheduled days. Four different dietary treatments were utilized, and for each treatment the parameters recorded were: total feed intake per bird (g/bird/day); total live weight gain (g/bird/day); Feed conversion ratio (g of feed eaten / g weight gain); and the mortality data. The designed routine of the trial was as follows:
1. The birds were in each case weighed as a group, hence the weight per bird and other individual characteristics within each group were averaged figures, arrived at by simple division.
2. In order to minimize statistical variations introduced by outside factors, care was taken to randomly distribute bird groups around within the trial environment (e.g. to ensure that all of one group would not be located in either a more or less favorable local environment). The LSD statistical approach was to be used in assessing the results.
3. The trial utilized 24 identical pens, each to contain 10 birds plus a brooder (for warmth) a waterer and suspended feeder.
4. Each bird was weighed at commencement of the trial and placed into one of five holding pens according to starting weight (lightest to heaviest). The birds were then evenly distributed into the 24 trial pens, so that –as far as practicable – each trial pen contained the same proportions of birds of the various starting weights.
5. Each pen of 10 birds was then weighed at the start and on every third day thereafter.
6. Feeders were weighed empty, then filled with circa 2kg of the appropriate experimental diet in the form of crumbled/broken pellets. (The topping up of feeders was done using only the designated diet composition for that pen).
7. To initially determine which treatment diet was used for each pen, the 24 pens were notionally divided into six blocks of four at the start, then randomly assigned one of the four dietary treatments into each of the four pens within a block.
8. Although the weighing was performed only on every third day after the start, each pen was checked daily. Water containers were cleaned, topped up and checked for flow and birds were checked for signs of ill health. Any dead birds found were removed and the weight recorded, then the combined weight of the remaining birds was recorded.
9. On every third day of the trial, the weight in each pen of the feed container plus remaining food was measured and recorded, then topped up with correct dietary treatment, then weighed and recorded again. All the birds in each pen were weighed as a pen group and the total recorded. (At all times the birds were handled gently).
For treatment #1, the trial records Excel file includes what must be a spurious figure for pen 20. The figure of 7139g over days 7-9 compares with the average of 1377g for other pens in the group. (Is it a mis-typed version of 1379??). The spurious figure has therefore been ignored and excluded from calculations, and averages produced using the remaining figures for the other pens in the group.
It was noted that the control treatment group (#1) produced the birds with the greatest averaged weight gain, though with a slightly greater amount of feed (circa 3%) consumed than treatment #2, the diet including 15% DDGS. However, because the averaged weight gain of the treatment #2 group was significantly less, it was the control group that produced the better food conversion ratio of the two.
Comparing the results of treatments #3 and #4, noting that the averaged figure for food consumed per bird was very similar for both groups (within less than 1%), the weight gain figures were quite different. Whilst the weight gain for the treatment #3 group was of a similar order to the results for treatments #1 and #2, the weight gain figure for treatment #4 (the 30% DDGS without additives) was much lower – only about 70% of the average value of gain for the other three treatments.
Interestingly, whilst the 30% DDGS content diet with the amino acid additives produced the best feed conversion ratio, the 30% DDGS diet without those additives produced the worst feed conversion ratio of the four diet treatments, indicating that the additives had a major effect.
It was noted from the records of the trial that total bird mortality was between 4 and 5%, and was not concentrated in any one diet treatment group. In fact it was approximately equal across all four groups, suggesting that no particular diet treatment was a contributory cause. According to an RSPCA publication “Behind Closed Doors - the truth about chicken bred for meat” (n.d.), the typical mortality rate in UK commercial broiler production equates to around 1 percent per week. As our trial lasted for a total of 28 days or just four weeks, the mortality rate experienced was not excessively high, although the sample size was relatively small for the mortality numbers to be considered statistically reliable.
The first hypothesis that we set out to prove or disprove was:
DDGS levels of up to 30% in broiler starter diets will not compromise bird growth or feed conversion efficiency.
In terms of feed conversion efficiency, the control group was only just behind the best with the group on treatment #3, which had 30% DDGS but with amino acid supplements included to ensure those specific dietary requirements were met. Given the addition of those supplements in treatment #3, the 30% level of DDGS did not appear to compromise feed conversion efficiency, although the birds (as previously mentioned) weighed on average some 150g less than those in the control group, which could be significant in terms of selling price for the commercial broiler producer.
The second hypothesis was:
Diets formulated to the same ME and CP content will produce the same bird performance.
In our trial this hypothesis was tested by treatments #3 and #4. Both featured the same ME and CP Values and 30% levels of DDGS, but treatment #3 had the amino acids supplements included. The results of the trial disproved the hypothesis. Whilst treatment #3 produced good weight gain and food conversion ratio results (almost as good as the control group), treatment #4 with the same ME and CP values produced the worst weight gain and food conversion ratio figures in the trial. The weight gain was – for example – just 65% of the averaged figure for the birds in the control group, while the feed consumed figure was of the same order as the other treatment groups.
The results of our trial seem to support other research into the subject. For example, Noll (2004), refers (p.4) to a broilers study conducted by Batal and Dale (2003), in which they suggested DDGS levels of up to 6% in broiler starter feeds would not [adversely] affect performance.
Also, a more recent article by Abdel-Raheem et al (March 2012), refers to “the highest level of inclusion in broiler diets (12 per cent)” as having adverse effects on bird performance, referring to research conducted in Egypt and in Austria. Their study – involving 240 birds – used three different dietary treatments which had DDGS levels of zero, six and 12 percent respectively. They too measured and recorded weight gain and feed intake but determined on a weekly basis for a total of five weeks. They found that over the duration of the 35 days of their trial, the addition of 12% DDGS into the diet caused a reduction in body weight of those birds compared with the control group. They also concluded that in their experiment’s environment, the 12% DDGS content reduced the birds’ ability to digest amino acids and some of the dry content of the diet treatment.
Another study by Wang et al (2008) produced somewhat similar findings. In their trial using 600 birds, DDGS content levels of 0, 15 and 30% were added to two basic diets (hence six different diet treatments in total, 100 birds in each). The results showed that the 30% level of DDGS resulted in reduced body weight compared with the 15% and 0% DDGS diets, although the researchers cautioned that inferior pellet quality at the higher DDGS level could have been a contributory factor.
A report published on “The Crop Site” (web), entitled “Substitution of DDGS for Corn, Soybean Meal in the US Feed Complex” (January 2012) has a Broilers section, where it refers to a study by Lumpkins (2004) that found that at DDGS levels exceeding 12% “gain and feed utilization were reduced.” However, they did mention that amino acid deficiency could have been a contributory factor. In our own trial, the amino acids addition to the 30% DDGS diet certainly seemed to reduce the negative effects of that level of DDGS; perhaps the effects of different levels of amino acids is a topic worthy of further research focused on that aspect.
Our trial did not include as an objective comparison of feed costs as a factor for consideration, although that is of course of major importance for the commercial broiler industry. An article entitled “Enzyme technology boosts performance of broilers fed DDGS” (2008) claimed that broiler producers can save circa $9 per metric ton of the gross feed costs. The article refers to studies conducted by Auburn and Purdue Universities that showed that adding certain enzymes to broiler diets supplemented with 10% DDGS could increase body weights by between five and eight percent and improve feed conversion by as much as six percent.
Another factor not considered in our nutrition trial but of importance to the broiler producing industry and ultimately to the consumer is meat quality. A study by Min et al (2011-2012) using six different treatments in a trial using 720 birds and running for six weeks, concluded that DDGS levels of up to 15% in broiler diets are acceptable and do not adversely affect the quality of the meat, although the researchers noted that the yellowness of the meat was increased and there was additional weight loss in the meat during cooking.
Abdel-Raheem S.M., R. Leitgeb and C. Iben. Effects of dietary inclusion level of distillers' dried grains with solubles (DDGS) from wheat and corn on amino acid digestibilities in broilers. (2011). International Journal of Poultry Science 10(12): 952-958. Retrieved from http://www.thepoultrysite.com/articles/2375/effects-of-dietary-inclusion-level-of-ddgs-from-wheat-and-corn-on-amino-acid-digestibilities-in-broilers
Behind Closed Doors - the truth about chicken bred for meat. (n.d.). RSPCA. Retrieved from http://www.agrowebcee.net/fileadmin/user_upload/faw/doc/reports2/RSPCA%20REPORT%20ON%20WELFARE%20OF%20BROILERS.pdf
Bonnardeaux, John. Potential Uses for Distillers Grains. (March 2007). Department of Agriculture and Food, Government of Western Australia. Retrieved from http://www.agric.wa.gov.au/objtwr/imported_assets/content/sust/biofuel/potentialusesgrains042007.pdf
DDG Feed More Valuable Than Traditional Corn, Soybean Rations. (October 25, 2011). Corn & Soybean Digest. Retrieved from http://cornandsoybeandigest.com/energy/
Enzyme technology boosts performance of broilers fed DDGS. (December 2008). Dupont Infdustrial BioSciences. Retrieved from http://biosciences.dupont.com/media/news-archive/news/2008/enzyme-technology-boosts-performance-of-broilers-fed-ddgs/
Lumpkins, Brett Stephen. Nutritional Value and use of Distiller’s Dried Grains with Solubles in the Feeding of Poultry. (2004). Retrieved from http://athenaeum.libs.uga.edu/bitstream/handle/10724/7789/lumpkins_brett_s_200408_ms.pdf?sequence=1
Min, Y.N., et al. Effects of dietary distillers dried grains with solubles concentrations on meat quality and antioxidant status and capacity of broiler chickens. (2011-2012. The Journal of Applied Poultry Research. Retrieved from http://japr.fass.org/content/21/3/603.abstract
Noll, Sally. DDGS in poultry diets: Does it make sense. (2004). Midwest Poultry Federation Pre-Show Nutrition Conf., River Centre, St. Paul, MN. March 16, 2004. Retrieved from http://www.ddgs.umn.edu/articles-poultry/2004-Noll-%20DDGS%20in%20poultry%20diets%20(MWPF04).pdf
Shurson, J., Noll, S. and Goihl, J. Corn By-Product Diversity and Feeding Value to Non-Ruminants. (2005). Department of Animal Science University of Minnesota. Retrieved from http://www.ddgs.umn.edu/articles-swine/2005-Shurson-%20(MNC)%20Corn%20by-product%20diversity.pdf
Substitution of DDGS for Corn, Soybean Meal in the US Feed Complex.” (January 2012). The Crop Site. Retrieved from http://www.thecropsite.com/articles/1134/report-substitution-of-ddgs-for-corn-soybean-meal-in-the-us-feed-complex
Wang, Z et al. Evaluation of Corn Distillers Dried Grains with Solubles in Broiler Diets Formulated to Be Isocaloric at Industry Energy Levels or Formulated to Optimum Density with Constant 1% Fat. (2008). International Journal of Poultry Sciences 7 (7): 630-637, 2008 ISSN 1682-8356. Retrieved from http://www.pjbs.org/ijps/fin1143.pdf