Field Evaluation of a Fullfat Soybean Meal Obtained with the Use of an Expander in Poultry Rations

Poultry Processing Articles >> Feed, Nutrition and Water

Summary
The use of an optimum quality fullfat soybean meal (FFSBM) in terms of protein solubility and availability is critical at any layer or broiler operation that looks for a maximum operation efficiency and profitability. For this reason, the protein digestibility index of a fullfat soybean meal obtained with the use of an expander (EFFSBM) with 37.3% of crude protein, 91.15% of protein solubility in potassium hydroxide, 0.06 of urease activity and 3.6 mg/gr of trypsin inhibitor was compared to a soybean meal (SBM) with 48 % of CP and a protein solubility index of 85.45%, 0.19 of urease activity and 2.5 mg/gr of trypsin inhibitor, in commercial rations for Ross broilers and both soybean products were obtained from the same source of soybeans. Soybean meal was used in T-1 and the EFFSBM in T-2 being both isocaloric and isonitrogenous. The difference in terms of CP, TSAA, lysine, threonine and tryptophane content between T-1 and T-2 in relation to T-3, then between T-3 and T-4 and finally between T-4 and T-5 was based on the percentage of difference in terms of protein solubility between the EFFSBM and the SBM, this time of 5.7% and equivalent to 0.42% of protein, considering that 7.4% of the total protein was supplied by the EFFSBM after including it at 20 %. The EFFSBM was then incorporated into starting and finishing broiler rations with different levels of protein (22% for T- 1 and T-2, 21.58%, 21.16% and 20.74% for T-3, T-4 and T-5 respectively in the starting period, and 18% for T-1 and T-2, 17.58%, 17.16% and 16.74% for T-3, T-4 and T-5, respectively for the finishing period). At 49 days no statistical difference (p>0.05) was observed among treatments for body weight gain (2617, 2621, 2636, 2631 and 2587) and feed conversion (1.988, 1.938, 1.946, 1.986 and 1.992).

The results obtained with this test allow for the presumption that when the expander is used to process soybeans into FFSBM, it is possible to obtain an additional benefit of 5.7% more in terms of CP, TSAA, lysine, threonine and tryptophane, due to a greater digestibility value resulting from the processing method. Knowing more about this new type of processing will allow the poultry industry to count on a more digestible source of both protein and energy, to meet the every time greater demand for highly digestible, good quality protein sources, of the new layer or broiler genetic lines. In addition to this, to count on this new type of EFFSBM will allow the poultry industry to optimize the use of protein in the rations, to reduce the metabolic load of excessive amounts of nutrients, and to formulate rations closer to the actual nutritional needs of the birds, all this always in favor of a better performance. Finally, for a better environment, the less nitrogen in the ration, the less potential pollution.

Introduction
For many years soybean meal (SBM) was considered a by-product derived from the oil industry (Kohlmeier, 1993). However, the massive consumption of SBM by the poultry and the swine sectors, forced the oil crushers to look for better ways to improve oil extraction, seeking to preserve the nutritional value of the SBM.

Ever since the poultry and swine industry started a process of modernization in the 60’s, where it was evident the industry needed of several ingredients to compound their feed. However, during the 80’s, these type of rations were simplified towards including less ingredients, and ending up in the use of mainly corn and SBM (Fernandez et al., 1994). At this respect in a study conducted by Kohlmeier (1993), it became evident that in the United States a higher demand for soybean meal came along with a smaller demand for other secondary protein sources, mainly those from animal origin. This situation was more critical when the first cases of Bovine Spongiform Encephalopathie (BSE or so called Mad Cow Disease) were registered in the EU, reaching the point when these ingredients were totally banned for their use in feed in some countries, and shifting to a more reliable protein source like SBM.

Through the years the soybean processors worldwide have been able to produce different kinds of SBM, most of the times extracting the oil with the use of solvents, although sometimes it was mechanical extraction. In relatively recent years, the feed industry adopted a new practice, the inclusion of fullfat soybean meal, which in most cases was obtained through extrusion, either wet or dry, and some other times using roasters if the final users were the ruminants. The typical composition of a full fat soybean meal (FFSBM) shows an ingredient with 7 to 12% moisture, 33 to 40% CP, 16 to 20% fat and between 5 and 6% fiber (Kohlmeier, 1993).

Regardless of the variation in the nutritional value of the different soy products based on quality, the soybean itself and the processing conditions and method, SBM continues to be the protein source for excellence, as FFSBM is for energy.

Although the use of FFSBM in poultry rations is already a well accepted practice in most parts of the world, it is advisable to continue doing research around this ingredient, seeking to increase its versatility and to do it more adaptable to the actual nutritional, environmental and economical needs of the poultry and feed industry. No doubt that every time worldwide the livestock sector is facing more restrictions to operate, from sanitary, when the animal protein sources are being banned, to ecological when the impact of manure deposition is limited.

Maybe one processing technology that is still not well known and that is the objective of this study, is the use of expansion. The concept of this type of equipment is conceived as a simplified, low cost extruder. The expander is able to generate heat above 90°C through a hydro-thermal process, that results in the expansion of the ingredients (Broz, 1997). Right from its beginning in Europe, in most of the pelleting processes, the expander is located between the conditioner and the pelleting machine, a practice that has been used for over 15 years. Only the introduction of expanders with high capacity output has enabled a common feed plant to apply HTST (High Temperature Short Term) technology on the factory floor with satisfactory results in terms of product quality as well as in terms of economic efficiency. The very rapid spreading of this technology worldwide can be considered revolutionary and proves expanders as reliable and competitive machines. (Peisker, 1994).

For the feed industry, the advantages of using an expander go from the simple processing of ingredients to the production of finished feeds. The temperature reached in this equipment not only allows to destroy pathogens, but also to inactivate anti-nutritional factors, like trypsin inhibitors in soybeans. At the same time this type of process allows to maintain a high protein solubility index, making of EFFSBM a more digestible ingredient.

Nowadays the industry and the society demand the production of more digestible feed, as a means to reduce the negative impact of disposing an excessive amount of nitrogen and phosphorus to the environment. A situation like this takes place when protein is fed in excess, or when the protein source has a poor digestibility index. At the end, the less nitrogen in feces, the less in the soil, and so the smallest the risk to pollute the environment (Weigel, 1999).

This way, recent research studies have been destined to generate information that allows the nutritionists to formulate rations according to the ideal protein concept. This concept not only considers the fact that the minimum nutritional requirements for maximum performance are covered, but also that the metabolic load is reduced when nutrients are included in excess.

Recently, the American Soybean Association in Mexico knew about the capability of a Mexican company, Avicultores y Productores El Calvario S.A. de C.V. (AYPECSA), to process soybeans with the use of expanders for what ASA collected samples for their study. After analyzing the samples, it was evident that the FFSBM obtained with an expander had a higher protein solubility index (of 92% in average), while it kept a low urease activity (0.06) and low levels of trypsin inhibitors, these last one no higher than 4 mg/gr. These results, besides knowing which are the needs of the poultry industry, encouraged ASA to conduct a feeding trial destined to evaluate the nutritional value of this new FFSBM. There is good scientific evidence that the protein solubility test conducted on representative samples of SBM or FFSBM shipments is correlated to performance in the field.

No scientific journal reports a similar trial or evaluation, for this reason the present test is a unique work, which will serve as reference for future work on this matter. This time the test was conducted in broilers, being the largest market for soy products in the world.

Materials And Methods
The trial was conducted at the Instituto Internacional de Investigacion Animal, S.A. de C.V., located at Villa del Marquez Queretaro in Mexico, at 1,800 meters above sea level. A total of 1,400 one-day old Ross broilers, with an average weight of 46.2 gr. were used at this test. Upon arrival at the farm, the birds were randomly assigned to four treatments (T- 2, T-3, T-4 and T-5) and one control group (T-1) with seven replicates of 40 birds each (20 males and 20 females).

The birds were housed in an experimental farm, similar to a regular poultry house, over a 10 cm thick chopped barley hay bed, providing only water during the first two hours after arrival and after that feed was provided.

The EFFSBM utilized at this feeding trial was obtained with the use of a Desmet expander, with a processing capacity of 10 MT/hour. Having 37.3% CP, 91.15% protein solubility in KOH, 0.06 of urease activity and 3.6 mg/gr. of trypsin inhibitor, the EFFSBM that was incorporated to practical starter (0 to 21 days) and finishing (22 to 49 days) broiler rations, with different levels of protein. The starter diets had 22% CP in both T-1 and T-2, and of 21.58%, 21.16% and 20.74% for T-3, T-4 and T-5, respectively. For the finishing period, the level of CP was of 18% for T-1 and T-2, and of 17.58%, 17.16% and 16.74% for T-3, T-4 and T-5, respectively. The SBM used in the study was obtained from the same source of soybeans that were used to obtain the EFFSBM, and had 48% CP, 85.45% of protein solubility index, 0.19 of urease activity and 2.5 mg/gr of trypsin inhibitor. The difference in terms of CP, TSAA, lysine, threonine and tryptophane content between T-1 and T-2 in relation to T-3, then between T-3 and T-4 and finally between T-4 and T-5 was based on the percentage of difference in terms of protein solubility between the EFFSBM and the SBM, this time of 5.7% and equivalent to 0.42% of the crude protein, considering that 7.4% of the total protein was supplied by the EFFSBM after including it at 20%.

Parameters Evaluated
During the test, the following parameters were evaluated, weight gain, feed consumption, feed conversion corrected to mortality, and percentage of mortality at 21, 35 and 49 days of age.

Results
Starting Phase (0 To 21 Days Of Age)
In relation to feed consumption, at the end of this period a significant statistical difference (p<0.05) was registered among treatments, being the highest in T-1 and the lowest in T-2, T-3 and T-5 (Table 3). In terms of weight gain, T-1 containing SBM was significantly higher than the rest of the groups. The variance analysis for feed conversion did not show any significant difference (p>0.05). In general terms, the values obtained with the four groups that contained EFFSBM had a similar response, with a slight trend towards a higher weight and feed conversion when there was a higher concentration of nutrients.

Growing Phase (22 To 35 Days Of Age)
During this period no significant difference (p>0.05) was observed among treatments for feed consumption, weight gain and feed conversion (Table 4). There is a numerical trend towards a better weight gain when EFFSBM was included in the rations with an equal or slightly less nutrient density than the control group (T-1) containing SBM, and also a slight decrement in body weight when nutrient density was reduced in the diets with EFFSBM. The best feed conversion ratios were obtained in the four treatments where EFFSBM was included, mainly when the nutrient density was higher.

Finishing Phase (36 To 49 Days Of Age)
For feed consumption, there is statistical difference (p<0.05) between treatments, where T-1 and T- 4 obtained the higher values, but with no significant difference among them, but so with treatments T-2 and T-5. When weight gain was analyzed and so feed conversion, no significant difference (p>0.05) was observed among treatments (Table 5). Again numerically a better weight gain and feed conversion were observed in the birds that consumed the rations containing EFFSBM and with a higher nutrient density.

Analysis With All The Phases (0 To 49 Days Of Age)
When all the parameters were analyzed using the data accumulated to the end of the trial, a significant difference was found (p<0.05) for feed consumption, being higher for T-1 and T-4.

However, no significant difference among treatments was observed for weight gain and feed conversion (Table 6). The three groups containing the EFFSBM and with a higher nutrient density numerically obtained a better weight and feed conversion than the control group (T-1) containing SBM.

Conclusion
1. The adequately processed EFFSBM is an ingredient with a higher availability of protein and aminoacids, probably due to a higher protein solubility index and in absence of anti-nutritional factors, mainly trypsin inhibitors, which in this case were not higher to 4 mg/gr, according to what the literature recommends (Dale, 1989).

2. The inclusion of EFFSBM in 20%, with a protein solubility index of 91.15% allowed to reduce the concentration of CP, TSAA, lysine, threonine and tryptophane by 5.7% in relation to a SBM with 85.45% of protein solubility, without affecting weight gain, or feed conversion in broilers to 49 days of age.

3. The protein solubility in EFFSBM is at least 91.15%, which is 6.15% higher than the average of the best of SBM in the market (with 85%). This validates that the EFFSBM is a better processing method in terms of preserving protein quality, while inactivating the anti-nutritional factors.

4. Given that T-3, T-4, T-5 had less protein and aminoacids, but had a similar performance among them, it can be deduced that there is a positive effect on performance when higher quality ingredients are used, probably due to a lower metabolic load. This last issue might suggest that it can be possible to reduce the safety margins of nutrients in the formula.

5. The test clearly shows that both SBM and EFFSBM, when adequately processed, are ideal for broiler feed, and that the combination of both ingredients (in this case up to 37%) contributes to obtain excellent economical and production results.

6. It is well documented that the laboratory level of KOH is a reliable predictor of in vivo performance.

7. In relation to the processing of EFFSBM, it is important to determine which are the ideal operating conditions for each piece of equipment (temperature, moisture and time), so that the plant obtains the desired EFFSBM quality.

8. Due to the fact that the cost of processing with expanders is similar to the cost of extrusion, this new processing method can be consider viable for the existing poultry integrators.

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