Production economics and pig health

It is estimated that in 2030 the world population will be close to eight billion people, which corresponds to an annual increase of 4%. In the same period, global food production is projected to increase by only 2% per year. Therefore, given that an increasing amount of grain and oilseed crops will be used for human food, a growing concern exists in terms of a shortage of conventional feedstuffs to be used in animal production. Additionally, legislation in some countries has banned the use of meat and bone meal in animal feedstuffs, which has increased the need for other protein sources, particularly those of vegetable origin.

One way to help meet the protein demands of a growing world population is to improve utilization of non-conventional feedstuffs in livestock diets, particularly in the regions where those feedstuffs are intensively produced. Another choice is to improve the utilization of fibrous materials. Considering that every year an estimated 230 million tonnes of fibrous material are produced annually in the form of a variety of byproducts, an improvement in the utilization of these materials in animal diets with a consequent reduction in environmental pollution could be of great importance.

Quality and nutritional value are also important aspects of feed ingredients that can be manipulated. Most feedstuffs contain some anti-nutritional factors. Soybeans and other legumes, for instance, contain non-starch polysaccharides (NSP), such as raffinose, stachyose and verbascose, in addition to phytate, trypsin inhibitors and lectins, leading to digestive problems, decreased performance, and environmental concerns. Pigs do not produce sufficient endogenous enzymes to efficiently break down the phytate molecule or to degrade NSP. Therefore, the addition of exogenous enzymes to swine feed formulations becomes an important means of improving the utilization of feedstuffs high in phytate or NSP.

This paper aims to review research conducted with an enzyme preparation containing α-galactosidase, amylase, cellulose, protease and pentosanase, called AllzymeTM Vegpro, developed by Alltech Inc., and its effects on swine performance and production economics.


Enzymes and substrates

Enzymes are natural catalysts of biological systems. They are molecular structures responsible for the chemical transformations occurring within an organism. Two important characteristics of enzymes are emphasized: catalytic activity and specificity. Enzymes present an active site allowing them to break down a specific chemical bond. They interact with only one or a few specific substrates (Table 1), catalyzing only one type of chemical reaction. Therefore, such catalytic action is very specific and is determined by the primary, secondary and tertiary structure of the enzyme. If any loss of stability occurs, leading to a modification of the secondary or tertiary structure, loss of catalytic action will result. Many factors can affect the three-dimensional characteristics of the enzymes and therefore catalytic activity including temperature, pH, humidity, substrate concentration and pressure, among others (Penz, 1998).


Applications for exogenous enzymes

COMPLEMENTING ENDOGENOUS ENZYMES IN YOUNG PIGS

The enzymatic action and production in the organism is sometimes dependent on the presence of a particular substrate. This is particularly true for the enzymes of the digestive system. During the first days of life, young pigs lack the enzymes needed to digest carbohydrates, lipids and proteins. Nevertheless, as soon as they begin ingesting solid feed, digestive enzyme capacity begins to develop (Penz, 1998). However, enzymatic development does not occur for all enzymes: cellulase, hemicellulase, pentosanase, ß-glucanase, xylanase, galactosidase, phytase, among others, are not produced in significant quantities by monogastrics even when the substrate is present.




The weaning period is extremely important as it has an impact not only on growth rate but also on future development. The major consequence, if special attention is not given to this period, is a negative effect on performance that will affect the pig for its entire life. Therefore, it is important to provide starter diets containing highly digestible ingredients in order to maximize feed intake and weight gain.

The digestibility of a particular feedstuff is dependent on the type and concentration of enzymes present in the gastrointestinal tract. Changes occur as the pig ages and also at weaning, when there is a change from sow’s milk to solid feed (Kitchen, 1997). By the time weaning occurs (in general between 3 and 4 weeks of age) lactase activity has declined, but activities of other enzymes have not yet began to increase (Figure 1).

Additionally, the existence of an approximately 7-day lag period has been demonstrated between the introduction of a new substrate to the diet (or an increase in the level of a particular substrate) and the corresponding increase in enzyme activities needed to utilize increasing levels of that substrate (Kitchen, 1997). This gap represents an opportunity to supplement with exogenous enzymes to complement those being produced in the gut to improve digestibility of starter diets.


ANTI-NUTRITIONAL FACTORS

Monogastric diets contain a group of substances that are either poorly digested or completely undigested due to lack of endogenous enzymes. The most common of these anti-nutritional factors present in ingredients are NSP, phytate, trypsin inhibitors, lectins, alkaloids, polyphenols, lignin, cellulose and hemicellulose.

Non-starch polysaccharides consist of an extensive range of plant polymers, including ß-glucans, pentosans, cellulose, hemicellulose, pectic substances and α- galactosides (raffinose, stachyose, verbascose).

Non-starch polysaccharides are present in significant amounts in feedstuffs. Legume seeds contain NSP in the form of oligosaccharides, hemicellulose and pectin, while grasses (eg., wheat and barley) contain ß-linked glucans and pentosans. α-Galactosides are members of the raffinose family of oligosaccharides (Figure 2). Table 2 lists some of the ingredients used in livestock diets and their main anti-nutritional factors and Table 3 presents the content and digestibility of NSP present in some ingredients commonly used in pig diets.







The raffinose family of oligosaccharide NSPs are insoluble and monogastrics are unable to digest them without the help of a specific exogenous enzyme (α- galactosidase) needed to hydrolyse these oligosaccharides to galactose and sucrose. Therefore, bacterial fermentation in the intestine instead of hydrolysis occurs, leading to production of gases and volatile fatty acids instead of monosaccharides and disaccharides released by hydrolysis. Thus NSP lead to digestive problems, and reduction in digestibility of nutrients. Furthermore, NSP reduce the absorption of protein, lowering the concentration of plasma urea and increasing the excretion of nitrogen (N) in the feces. Figure 3 presents a schematic representation of the effects of NSP in monogastrics.







Supplementation with exogenous enzymes is one way to minimize the anti-nutritional effects of the NSP. Other alternatives include pre-digestion of feed and reduction of NSP in feedstuffs by means of genetic modifications or natural mutations in the plant population (De Souza, 2003).

Exogenous enzymatic supplementation may increase the efficiency of the endogenous enzymes, reducing the amount of nutritional residues in the large intestine and lowering the action of the microorganisms in that part of the intestine (Wenk, 1993).


AllzymeTM Vegpro

DEVELOPMENT AND EARLY STUDIES

AllzymeTM Vegpro is an enzyme complex containing the enzymes α-galactosidase, amylase, cellulase, protease and pentosanase. According to Charlton (1996), Vegpro was developed in 1993 as a result of joint research between Alltech Inc. and the British Agricultural Development and Advisory Service (ADAS) with the objective of examining the potential for enzyme supplementation of vegetable protein sources. Soybean meal and the modified rape/pea/bean protein products used in poultry diets were emphasized.

Following evaluation of the raw materials, in vitro assessment of enzyme complements were conducted at Alltech’s European Bioscience Centre in Ireland, and in vivo evaluations were tested in Scotland at the Roslin Research Institute where trials measuring N-corrected true metabolizable energy (TME) in broilers were conducted.

The practical use of Vegpro in diets was first outlined by Charlton (1996), suggesting ways of using this enzyme complex:

• Simple addition to the diet: Vegpro added on top of the standard diet (without reformulation) improves digestibility of soybean meal and, consequently, improves growing pig performance. Therefore, its use was suggested in pre-starter and starter diets for pigs.
  
• As another raw material in the diet: Using the improvements observed in energy, crude protein and amino acid digestibility of soybean meal, Vegpro can be added to the formulation matrix (Table 4) and used in least-cost diet formulation.

The utilization of Vegpro has been directed to three different production phases: young pigs, growing-finishing pigs, and reproduction. A series of on-farm trials adding Vegpro to growing pig diets was conducted during autumn and winter of 1995/1996 by Kitchen (1997).

A control diet containing cooked and uncooked cereals, cereal grain by-products, oilseed products and including soybean meal, fish meal, whole heat-treated oil seeds, milk products, vegetable oils, vitamins and trace minerals was used. Vegpro was added to the control diet at 500 g/tonne of the test diet. Five replications were fed the control diet and four replications were fed the test diet. Pigs fed the test diet consumed more feed, but converted it better than pigs fed the control diet (Table 5). Consequently, they gained an average of 60 g more per day than the pigs fed the control diet. The ratio of test diet:control diet for daily live weight gain was 1.1 and for feed conversion the ratio was 0.95. Dierick and Decuypere (1994) found similar results for similar blends of enzymes.


CURRENT USES OF VEGPRO

Starter diet applications

As stated previously, the inclusion of soybean meal in the diet during the period after farrowing and post-weaning is very limited due to low secretion of proteolytic enzymes by the young pig and the presence of anti-nutritional factors. Such anti-nutritional factors are responsible for hypersensitivity reactions and damage to the intestinal mucosa, leading to diarrhea, poor performance and even death.




The addition of Vegpro in diets for young pigs has the primary purpose of supplementing the endogenous enzymes, leading to an adequate digestion of the nutrients present in soybean meal and a reduction of antinutritional factors. Vegpro supplementation thus ultimately leads to higher weight gain and more efficient feed conversion. Knowing the existence of a positive correlation between performance in this phase and during the growing-finishing phase, the addition of Vegpro to diets fed young pigs is of increasing interest.

From weaning to approximately 50 days of age the recommendation is the addition of 2 kg Vegpro/ton of diet, on top (as an additive). Commercial response is illustrated by research conducted with 2130 post-weaning pigs (17 days of age) on a commercial farm in Brazil in which Vegpro was added as a dietary additive at 2 kg/ ton. Pigs fed the diet with Vegpro had higher final weights at 63 days of age (26.88 vs. 25.43 kg) and also higher daily weight gains (463 vs. 442 g/day), which reduced cost of production for the initial phase (Carvalho, personal communication).


Grow-finish diets: reformulation to reduce diet cost

For the growing and finishing stages of pig production the purpose of exogenous enzyme supplementation is also to release otherwise unusable nutrients and improve digestibility; however, improved sanitary/environmental conditions are also an important response. Reduced intestinal NSP means less substrate is available for unwanted gut bacterial growth, there is reduced loss of nutrients via excretion and consequently less potential for pollution.

The increased nutrient digestibility with Vegpro addition to growing-finishing diets must be considered during diet formulation in order to maximize benefits in terms of reduced diet cost. Hannas and Pupa (2003 personal communication) developed nutritional matrixes for use of Vegpro in diets containing soybean meal with the main purpose of reducing diet costs. The nutritional matrixes represent the nutritional equivalency of Vegpro and soybean meal, and were estimated based on results obtained with Vegpro on digestibility and performance of pigs at different ages and production periods.

Three matrices were obtained (Table 4), which are are used according to the amounts of soybean meal and Vegpro added to a given diet (Table 6), keeping a constant relationship between substrate and enzyme.




Every matrix must be added to a least-cost formulation as a different ingredient. As an example, if a grower diet contains 25% soybean meal, then matrix 2 is selected and the diet reformulated with the addition of 0.50 kg Vegpro/tonne. On the other hand, if the diet contains 30% soybean meal, matrix 1 is used and the diet is reformulated adding 0.75 kg Vegpro/tonne.

In Brazil, under different production systems, reductions of diet costs between 0.5 and 1.8% along with similar or even better performance have been obtained with the utilization of Vegpro in reformulated diets. Other benefits include reduced excretion of of N (and other nutrients) and a better utilization of protein sources.
Lindemann et al. (1997b) worked with growingfinishing pigs (average initial and final weight of 26 and 109 kg, respectively) to study the effects of Vegpro on performance. Pigs were fed either a high density, corn/soybean meal diet, or a lower density, corn/soybean meal/wheat middlings diet with or without Vegpro.

Growing pigs (between 26 and 63 kg) fed the corn/ soybean meal diet with Vegpro had higher daily weight gain (P<0.06) and better feed conversion (P<0.10) than pigs fed the same diet without the enzyme complex. Daily weight gain was unaffected in grower pigs fed the corn/soy/wheat middlings diet although pigs supplemented with Vegpro had numerically better feed conversion. Similar responses were noted in finishing pigs (between 63 and 109 kg), although of a smaller magnitude in comparison to the grower period. Overall, pigs fed the corn/soy diet with Vegpro had higher daily weight gain (P<0.05). They also had a numerical better feed conversion efficiency. There were no significant differences in performance between pigs fed corn/ soybean meal/wheat middlings with or without Vegpro (Table 7).




In another trial, Lindemann et al. (1997a) fed weanling pigs (21.4 days and 6.8 kg) diets containing increasing levels of Vegpro (0, 0.075 and 0.15%). As the level of Vegpro increased, a linear trend toward increased daily gain (366, 372, 379 g/day) and feed intake (521, 521, 529 g/day) was observed for the first three weeks after weaning. Additionally, a significant linear improvement (P<0.07) was observed for feed:gain ratio (1.45, 1.40, 1.39) as the level of Vegpro increased.

Pluske (1998) found an average increase of 6.4% in energy digestibility, 5.5% in organic matter digestibility, and 2.7% in crude protein digestibility of soybean meal with Vegpro in comparison to a control diet without the enzyme (Figure 4). Other research has shown an increase in digestibility of essential and non-essential amino acids of soybean meal with the addition of exogenous enzymes to the diets (Table 8).

The utilization of enzymes in pig diets in Brazil is growing steadily each year. According to Pupa et al. (2005), the use of enzymes is roughly 25% in pre-starter diets and approximately 50% in growing and finishing diets. The same percentages are seen in gestation and lactation diets, respectively.







Effects on amino acid digestibility

Soybean meal is the major protein source for swine diets in Brazil, corresponding to 15 to 35% of the total. As previously stated, although this ingredient is considered highly digestible, the presence of anti-nutritional factors and NSP impair swine digestive processes and nutrient utilization. The addition of Vegpro to swine diets improves nutrient digestibility and reduces anti-nutritional factor impact. Therefore, Vegpro promotes direct and indirect benefits to pig production.

Working with growing pigs in Brazil, Costa et al. (2005) determined the true ileal amino acid digestibility of soybean meal with and without Vegpro. Enzymehydrolyzed casein was used to determine amino acid endogenous losses. Though a high coefficient of variation associated with the analysis precluded statistical separation of the means apart from histidine digestibility, numerical increases for the majority of amino acids were noted in response to Vegpro (Table 9).




Enzymes are also being used in gestation and lactation diets. De Souza (2003) found a significant increase in nitrogen digestibility when protease and cellulase were added to the diets to the end of gestation. The addition of the same enzymes to a lactation diet increased dry matter (83.2 vs. 81.0%), nitrogen (81.5 vs. 78.9%) and gross energy digestibilities (85.0 vs. 83.8%), in comparison to a control diet without the enzymes.


Conclusions

Projections for human population growth suggest that demand for dietary protein will steadily increase. Enzyme supplementation improves ability to use existing protein sources with maximum efficiency while providing opportunities to expand use of new dietary ingredients and by-products. Research and practical experience with Vegpro has demonstrated increased utilization of soybean meal in pig diets, with greatest economic impact, performance and environmental advantages realized when higher digestibilities are accounted for in the formulation matrix.


References

Charlton, P. 1996. Expanding enzyme applications: higher amino acid and digestibility for vegetable proteins. In: Biotechnology in the Feed Industry, Proceedings of Alltech’s 12th Annual Symposium (T.P. Lyons and K.A. Jacques, eds). Nottingham University Press, UK, pp. 317-326.

Costa, L.F., M.I. Hannas, J.M.R. Pupa, D.C. Lopes and A. Corasa. 2005. Ileal amino acid digestibility of soybean meal with the enzyme complex Vegpro for swine. In: Nutritional Biotechnology in the Feed and Food Industries, Proceedings of Alltech’s 21th Annual Symposium. (Suppl. 1, abstracts of posters presented) Lexington, KY, May 23-25.

De Souza, A.L.P. 2003. Assessment of dietary enzyme supplementation on ileal and total tract digestibilities in gestating and lactating swine. Ph. D. Dissertation. University of Kentucky, Lexington, KY, p. 165.

Dierick, N.A. and J.A. Decuypere. 1994. Supplementary enzymes to improve utilization of pig diets. Proceedings 45th Annual Meeting of EAAP, Edinburgh.

Hartman, P.A., V.W. Hays, R.O. Baker, L.H. Neagle and D.V. Catron. 1961. Digestive enzyme development in the young pig. J. Anim. Sci. 20:114.

Kitchen, D.I. 1997. Enzyme applications in corn/soya diets fed pigs. In: Biotechnology in the Feed Industry, Proceedings of Alltech’s 13th Annual Symposium (T.P. Lyons and K.A. Jacques, eds). Nottingham University Press, UK, p. 101.

Lindemann, M.D., J.L. Gentry, H.J. Monegue and G.L. Cromwell. 1997a. Determination of the contribution of an enzyme combination to the growth performance of pigs. J. Anim. Sci. 75(Suppl. 1):184 (Abstr.).

Lindemann, M.D., J.L. Gentry, H.J. Monegue, G.L. Cromwell and K.A. Jacques. 1997b. Determination of the contribution of an enzyme combination (Vegpro) to performance in grower-finisher pigs. In: Manipulating Pig Production VI (P.D. Cranwell, ed). Australasian Pig Science Association, Werribee, Victoria, Australia, p. 247.

Penz, A.M. 1998. Enzimas em rações de aves e suínos. In: Reunião Anual da Sociedade Brasileira de Zootecnia, 35. Botucatu-SP. Anais, pp. 165-178.

Pluske, J.R. and M.D. Lindemann. 1998. Maximizing the response in pig and poultry diets containing vegetable proteins by enzyme supplementation. In: Biotechnology in the Feed Industry, Proceedings of Alltech’s 14th Annual Symposium (T.P. Lyons and K.A. Jacques, eds). Nottingham University Press, UK, p. 375.

Pluske, J.R. 1998. Effect of Allzyme™ Vegpro on apparent digestibility of vegetable proteins by pigs. Monogastric Research Centre, Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand. UL 5.4 October 1998.

Pupa, J.M.R., U.A.D. Orlando, I.L. Lima and M.I. Hannas. 2005. Níveis nutricionais usados nas rações de suínos no Brasil. In: Simpósio Internacional sobre Exigências Nutricionais de Aves e Suínos. Viçosa, MG, Brasil (in press).

Wenk, C. 1993. What are the benefits of carbohydrases in the nutrition of monogastric farm animals? In: Enzymes in Animal Nutrition, Proceedings of the 1st Symposium. Kartause Ittingen, Switzerland. pp. 41- 48.



Authors: EDUARDO G. XAVIER¹, FERNANDO RUTZ¹, M.I. HANNAS² and J.M.R. PUPA^2
1 Universidade Federal de Pelotas, Rio Grande do Sul, Brazil
² All Nutri Consultoria em Planejamento e Nutrição Animal, Viçosa, Minas Gerais, Brazil