Review of effects of enzyme supplementation of a fibrous diet on the performance of local (Mong Cai) and exotic (Landrace x Yorkshire) pigs in the post-weaning and growing periods

 
Tran Thi Bich Ngoc

 National Institute of Animal Husbandry, Hanoi, Vietnam
bichngocniah75@hotmail.com
 

1. Introduction

 Pig production is one of the major priorities for rural development in Vietnam. The pig population (Table 1) in Vietnam increased by 6.0% annually from 2000 to 2005 (General Statistical Organization, 2005, cited by Kinh and Hai, 2006). It has been estimated recently that around 80% of the total pig population are raised in traditional smallholder systems (Lapar et al 2003). Commercial feeds are rarely used in smallholder farms because these are expensive, and therefore diets are mainly based on rice bran, broken rice, maize, vegetables, and agricultural by-products, like sweet potato vines, cassava leaves, cassava residue, non-dehulled groundnut cake, and other locally available by-products, which are characterised by a high fibre content and low protein and energy contents (Loc et al 1996). When included at high levels, these may decrease the digestibility of energy and other dietary components (Fernandez and Jørgensen, 1986; Noblet and Le Goff, 2001; Len et al 2006a,b) and result in low performance.    

Today, exotic breeds such as the Landrace, Yorkshire and Duroc have developed rapidly (Ly, 2000), especially in the urban areas of Vietnam, due to the tendency towards rearing exotic pigs to meet the higher demand of consumers for both quantity and quality of meat. However, the Mong Cai (MC) breed has better characteristics with regards to reproduction, is adapted to the hot climate and is more tolerant of high-fibre diets than exotic breeds (eg. Landrace x Yorkshire, LY). Recently, Khieu Borin et al (2005) and Len et al (2006a) indicated that MC pigs can utilize diets containing high fibre levels more efficiently than improved breeds. On the other hand, Ly et al (1998) and Kemp et al (1991) did not observe any effect of breed on the digestibility of dietary components in high-fibre diets.

Young pigs have a limited ability to effectively utilize diets containing lower quality ingredients with high fibre content. Besides, pigs do not secrete endogenous enzymes that break down plant fibre (Fernando and Feuchter, 2004). However, by adding enzymes to feed, the digestibility of the components can be enhanced, leading to greater efficiency in the production of animal products such as meat and eggs. Some studies have shown that dietary enzyme supplementation for pigs improved the nutrient digestibility as well as performance (Suga et al 1978; Omogbenigun et al 2004; Xia Meisheng, 2000). Feed enzymes in diets would be expected to work more efficiently for piglets (Thomke and Elwinger, 1998) and when matched to specific target substrates  (Bach Knudsen, 1997).

The objective of this study was to evaluate the effect of fibrous diets, with or without enzyme supplementation, on ileal and total tract digestibility and performance of local (Mong Cai, MC) and exotic (Landrace x Yorkshire, LY) weaned piglets.

2. General discussion

2.1 Feed resources for pigs in Northern Vietnam

Recently, the availability of commercial feeds has increased, and compound feeds are also mixed with home-made diets to improve daily gain. However, nutritionally imbalanced diets for pigs are still typical on smallholder farms.  Better utilization of locally available feed resources for pigs is thus very important. Several studies have been carried out to evaluate the effect of using local feeds such as sweet potato (Giang, 2003, cassava foliage (Khieu Borin et al 2005) or cassava residue and rice bran based diets (Len et al 2006a,b, 2007) in diets for post-weaning and growing pigs, indicating both reduced digestibility and performance. This study is concerned with locally available fibrous feed resources, rice bran and cassava residue.

Rice bran is the most important rice by-product. It is available in rural areas of Northern Vietnam where smallholder pig production is dominant. Rice bran is a good source of B-vitamins and is fairly palatable to farm animals. For pigs, rice bran should not exceed 30-40% of the total ration to avoid soft pork; in the final weeks of fattening, lower levels must be used. Rice bran is often adulterated with rice hulls, so it has a variable crude fibre content of between 7 -25% (Chinh et al 2001) and was found to be 22.2 % in this study (Paper I and II).

In Vietnam, cassava is the third crop after rice and maize, with about 337,000 ha planted in 2002 (FAOSTAT, 2003). Cassava processing for starch has developed rapidly, especially in the rural areas. It is estimated that about one third of cassava root production is now used for starch production (FAOSTAT, 2003), but this operation is mainly at artisan level under farm household conditions. Besides getting benefits from selling cassava starch, farmers could get more benefit from raising animals using diets based on cassava residues as an available feed resource. The residues from the processing of cassava root under farm household conditions were found to be high in crude fibre (CF) and Neutral Detergent Fibre (NDF) content (16% and 45% on a DM basis, respectively [Len et al 2006a,b, 2007] and 14.5% and 40.1% in this study [Paper I and II]).

How to improve fibrous diets in terms of digestibility and performance for pigs is an important question for pig researchers in Vietnam. 

2.2 Dietary fibre

Dietary fibre consist of non-starch polysaccharides (NSP) and lignin, which are the principal compounds of cell walls (Bach Knudsen, 2001). The main constituents are cellulose, hemicellulose and lignin. Lignin is not a carbohydrate, but it consists of very branched networks tighly linked to cell-wall polysaccharides (Iiyama et al 1994) and is therefore included in dietary fibre. Pigs do not secrete endogenous enzymes that break down plant fibre (Fernando and Feuchter, 2004). The main segments where NSP are broken down in the large intestine of both piglets and older pigs are the caecum and proximal colon, which have large amounts of bacteria that will break down fibre into volatile fatty acids (VFAs) (Gdala et al 1997). The VFAs can be absorbed by the animal and serve as an energy substrate.

2.3 Effects of dietary fibre on nutrient digestibility

NSP are degraded to varying degrees depending on the botanical origin of the fibre material (Graham et al 1986a). Several researchers have shown that the proportion of cereal NSP digested in the large intestine varies from 48 to 95% (Graham et al 1986a; Chabeauti et al 1991; Gdala et al 1997). Variation in the digestibility of different fibre sources has also been documented by Dierick et al (1989) in a review article. The digestibility of the fibre in beet pulp, lupin hulls, soy bean hulls, wheat bran and clover was higher than in grasses, alfalfa, maize hulls, oat hulls and maize cobs. Lekule et al (1990) showed that the digestibility of nutrients, especially energy, was very variable, and differed between different tropical feedstuffs when fed to pigs. Similarly, Dung et al (2002) found that the coefficient of total tract digestibility of NDF for whole ground rice and rice bran was different from that of brewers’ grain, cassava residue, copra meal and tofu residue.

Level of fibre in the diet is also an important factor affecting digestibility. As the level of fibre increases, digestibility of nutrients, especially of energy, decreases. In studies reported by Len et al (2006), Lindberg and Andersson (1998) and Högberg and Lindberg (2003), the inclusion of fibre in the diet reduced the digestibility of energy and dietary components. These findings are confirmed by the results of Paper I, where the ileal and total tract digestibility of organic matter (OM), crude protein (CP), CF, NDF, ADF and amino acids was higher in the low fibre diet than in the high fibre diet. For young pigs, the negative effects of dietary fibre on digestibility of nutrients and energy were found to be higher than in finishing and adult pigs (Fernandez and Jørgensen, 1986; Noblet and Le Goff, 2001; Le Goff et al 2002a, b, 2003). It seems then that the response of pigs to fibrous diets is different, and depends on their age and live body weight. In a study reported by Len et al (2006b), it was found that the negative effect of high-fibre diets on growth rate and feed conversion ratio in the pig in the growing period (2 to 4 months of age) was very clear, but this effect was not observed during the finishing period. The negative impact of increasing dietary fibre content on the total tract digestibility of dietary components in the current study (Paper I) was smaller than that in a previously reported study in growing pigs (Len et al 2006a) and in piglets fed sweet potato vine-based diet compared with a basal diet (Len et al 2007). This could be due to different chemical properties of the fibre sources in the studies (Henry, 1976; Chabeauti et al 1991; Len et al 2007), resulting in different digestibility. Furthermore, enzyme supplementation had a greater positive effect on digestibility in a high fibre diet compared to a low fibre diet (Paper I). Len et al (2006a) and Noblet and Le Goff (2001) showed a series of regression equations to express the relationship between fibre level and digestibility of energy and other nutrients. In most equations, NDF, CF and ADF were always closely related by negative coefficients. Based on those equations it can be concluded that level of dietary fibre is negatively linearly correlated with digestibility. An increase in the fibre content in the diet from maize cobs (Ndindana et al 2002) or sweet potato root and vines (Giang et al 2003) resulted in a decrease in digestibility of all nutrients. A similar conclusion was reached by Fernandez and Jørgensen (1986) and Le Goff et al (2002a). The negative effects of dietary fibre are partly a result of an increased digesta flow rate and inhibition of the exposure of digesta to enzymes, and also increased endogenous nitrogen, which is an additional factor reducing apparent nitrogen digestibility (Jørgensen et al 1996; Rainbird and Low, 1986).

However, there are several benefits of dietary fibre, due to the fact that it increases feed intake and stimulates peristalsis in the gastro-intestinal tract. In addition, the energy contribution of VFA from the fermentation of fibre in the hindgut is not negligible. According to Vervaeke et al (1989) between 1.3 and 15.6% of the net energy for maintenance and production is supplied from energy yielded in hindgut fermentation.

2.4 Supplementation of enzymes to pig diets

To achieve high production efficiency in the pig industry at low cost, a continuous improvement in the utilization of diets and of a wide range of dietary ingredients is crucial. Smallholder pig farms use commercial feeds in combination with certain by-products, and profitability is highly dependent on the relative cost and nutritive value of the selected feedstuffs. For these reasons, a continuous effort has been made to understand the complex nature of feed components. Feed enzymes increased the digestibility of nutrients (Paper I), leading to improved pig performance (Paper II) and thus can contribute to feeding an ever-growing human population. One of the problems in the pig industry is the use of drugs like antibiotics and growth promoters, which have a harmful impact on human health and the environment. Substitutes for these chemically synthesized drugs must be harmless, environmentally friendly, and "natural." Enzymes may be able to meet these requirements.

Biochemically, enzymes are proteins consisting of individual amino acids, but they may also contain other substances or cofactors, such as vitamins and minerals. Commercially available feed enzymes are natural products, produced by microbial fermentation. Enzymes, as biological catalysts, are involved in all anabolic and catabolic pathways of digestion and metabolism. On the one hand, they enable the pathways to operate efficiently under the metabolic conditions and act as regulators of individual processes. Because of these characteristics, interest is growing in the use of enzymes to improve animal performance.

A wide range of enzyme products for animal feeds are now available to degrade substances such as phytates, which can be degraded by phytase, glucans, that can be degraded by beta-glucanase, starch that can be hydrolysed by amylase, protein by proteinases, pectin-like polysaccharides by pectin methyl esterases, xylan by xylanases, and raffinose and stachyose by mixtures of mannanase and pullulanase. Hemicellulose and cellulose can also be degraded by mixtures, for example whole cellulases.

2.5 Effects of enzyme supplemented diets on the nutrient digestibility and performance of pigs

 Locally available feedstuffs such as rice bran, and cassava residue contain fibre or non-starch polysaccharides, and pigs do not produce the necessary digestive enzymes to degrade them (Fernando and Feuchter, 2004). Fibre decreases the digestibility and the nutritional value of a diet partly through an increase of the viscosity in the gastrointestinal tract (Bedford, 1995). Degradation of such cell wall components by supplementation with exogenous enzymes may enhance the nutritional value of the diet for the pig (Partridge, 2001). Some studies showed that there was a positive effect of enzyme supplementation on the digestibility of nutrients in both ileum and total tract in piglets (Diebold et al 2004; Li et al 1996; Omobenigun, 2004). The results in Paper I also indicated that enzyme supplemented diets showed higher nutrient and amino acid ileal and total tract digestibility than the diet without enzymes. Older pigs can utilize high-fibre diets better than piglets, because aging is associated with an increase in bacterial activity in the large intestine (Graham et al1988). Therefore, the most beneficial effect of feed enzymes is likely to be found in diets for newly weaned piglets (Thomke and Elwinger, 1998). This finding is agreement with the results of Paper I and Paper II, in which enzyme supplementation of diets for post-weaning piglets had a significant effect on nutrient and amino acid ileal and total tract digestibilty, as well as performance in terms of daily weight gain and feed conversion ratio, while no influence was found on performance in growing pigs. Similarly, in other studies with growing pigs, there was no difference found in either digestibility coefficients of nutrients (Thacker et al 2002; Graham et al 1986b, 1989) or average daily gain and feed efficiency between diets with or without enzyme supplements.

 However, in our studies ( Tran Thi Bich Ngoc et al (2007a,b), the improvements in ileal and total tract digestibility of nutrients, average daily gain and feed gain ratio are different compared with some other studies (Table 2 and 3). This can be explained by the fact that different substrates respond differently to different enzymes. If the chemical composition of the feed ingredients of the diet are determined (Bach Knudsen, 1997), which feed enzymes are likely to be effective can be selected. There are several enzymes available for degrading cell wall components, for instance pentosanases, ß-glucanases, α-galactosidases (Dierick and Decuypere, 1994), cellulases and xylanases (Bhat and Hazlewood, 2001), designed to target different substrates.

2.6 Breeds of pig in Northern Vietnam 

The pig can be considered to be the most important domestic animal in Vietnam. Due to the high population density in most parts of Vietnam and the resulting limitations in the availability of land for cropping, pig rearing is considered to be an important activity of farm households (Thuan et al 2000). For a long time, animal production in Vietnam has been based on local genotypes (Lemke et al 2000). In 2002, indigenous pigs accounted for 26% of the total pig population (Country Report of Vietnam, 2003). They are predominantly kept by smallholders in rural areas and are well adapted to farm conditions where feed is poor in terms of nutrient value, and sometimes scarce (Rodriguez et al 1997). However, the productivity of local pigs is also low, for instance with low growth performance and high feed conversion ratio (Hai and Nguyen, 1997). Due to the tendency towards rearing exotic pigs to meet the higher demand of consumers for both higher quantity and quality of meat, exotic breeds such as the Large White and Duroc have also developed rapidly (Ly, 2000), especially in urban areas. This means that the proportion of local pigs in the total pig population in Vietnam is gradually decreasing due to replacement by exotic and crossbred pigs. 

2.6.1 Mong Cai breed

In the Northern part of Vietnam, local breeds like the Mong Cai originated in the Northeast (Duyet and Duong, 1996), in the Red River delta, and in the coastal provinces Hai Phong and Thai Binh (Thien et al 1996). It has a small to medium body size, and small, upright ears. The head and body are black, with a white band running from one side of the abdomen over the shoulder to the other side of the abdomen, making a black saddle over the middle of the swayed back. The Mong Cai is characterised by high prolificacy compared to other local pig breeds, so it has become the major sow line in Vietnam (Table 4) in order to produce breeding stock.

2.6.2 Exotic breeds

Exotic breeds, mainly Landrace, Yorkshire, Hampshire and Duroc, have been imported in Vietnam for a long time. They play an important role in improving the pig stock in order to meet the development of pig production to fulfill the domestic demand for pork and to produce pork for export. Exotic breeds are used for cross-breeding for commercial production. Crossing programs usually include Yorkshire x MC, Landrace x MC, and Yorkshire x (Landrace x MC). Exotic breeds and crossbreds are often kept in the big farms and in peri-urban areas and show higher production performance under favourable conditions (Van et al 2001). In 2000, about 60% of the pig population was commercial crossbreds and exotics (Department of Livestock, 2006), and had increased by 27.6% in 2005, compared to 2000 (Table 5).

2.7 Effect of breed on nutrient digestibility and performance of growing pigs

The effects of genotype on the digestibility of nutrients in high fibre diets have been reported by many researchers (Ndindna et al 2002; Fevrier et al 1992; Len et al 2006a; Len et al 2007; Khieu Borin et al 2005). The results implied that indigenous pigs can digest fibrous diets better than improved pigs. These findings are similar to our results in Paper I, with the exception of amino acid ileal digestibility. The explanation put forward is that indigenous pigs have higher capacity of the gastro-intestinal tract and microflora activity in the hind gut than improved pigs (Jørgensen et al 1996; Freire et al 2000). Freire et al (2003) also found that the Alentejano breed of Spain, had a higher digestibility of fibrous diets than an improved breed (Duroc x Landrace), and this was attributed to a better adaptation of the enzymatic activity, namely xylanase and cellulase, of the caecal microflora to degrade the cell wall constituents of the diets. Nutrient total tract digestibility of both Mong Cai and Landrace x Yorkshire in our study (Paper I) was higher than in a previously study reported by Len et al (2007). This can be explained by the different fibre sources (Henry, 1976; Chabeauti et al 1991; Len et al 2007) and fibre levels (Len et al 2006; Lindberg et al 1998; Högberg and Lindberg, 2003) that resulted in the differences nutrient digestibility.

In contrast, Ly et al (1998) showed the opposite result, and found that Creole indigenous pigs in Cuba did not have better digestion of high fibre diets than improved pigs. Fermentation of fractions of NSP of different breeds is different due to differences in the microbial populations in the large intestine, with different VFA patterns observed (Morales et al 2002). Moreover, the effect of breed on digestibility also depends on dietary fibre level, because in some breeds this effect is only seen when they are fed high fibre diets (Fevrier, et al 1992; Kemp et al 1991).

Pig performance is affected very clearly by genotype (Len et al 2006b; Khieu Borin et al 2005). These findings are agreement with the results of Paper II, where there were significant differences found in average daily gain, feed conversion ratio and feed and nutrient intake between Mong Cai and Landrace x Yorkshire. The difference between Mong Cai and Landrace x Yorkshire for ADG was 65.5% units, and 45.5% units for FCR. The explanation for these differences is the lower genetic growth potential and also the greater relative weight and length of the gastro-intestinal tract of the Mong Cai compared to Landrace x Yorkshire (Len et al 2007).
 

3. Conclusions

• High fibre content in the diet reduced dietary component digestibility at the ileum as well as the total tract in piglets.

• Although there was no effect of breed on the coefficient of ileal apparent digestibilities of nutrients, the Mong Cai had higher coefficient of total tract apparent digestibilities of nutrients than Landrace x Yorkshire. The results from this study thus suggest that high fibre diets are more appropriate for indigenous than for exotic pigs.

• Feed and nutrient intake as a proportion of body weight was significantly higher in the Mong Cai than in the Landrace x Yorkshire. However, average daily gain and feed efficiency were significantly higher in the Landrace x Yorkshire.

• Enzyme supplementation of the high fibre diet improved the digestibility of all dietary components at ileum and total tract, but there was no effect of enzyme supplementation of the low fibre diet.

• Feed enzymes were more efficient in the post-weaning period than in the growing period. There was a significant positive effect on average daily gain and feed conversion ratio in post-weaning piglets, but no effect in growing pigs. Average daily feed intake was not influenced by enzyme supplementation.

4. Acknowledgements

 This study was carried out at the Station of Research and Testing of Animal Feed, National Institute of Animal Husbandry, Hanoi, Vietnam during 2006, with a grant from the Swedish International Development Authority (Sida/SAREC) and support from the Swedish University of Agricultural Sciences, Department of Animal Nutrition and Management. I am very grateful to their support of this study. I would like to thank the National Institute of Animal Husbandry, Hanoi, Vietnam for allowing me two years study leave and for helping me to carry out the studies. I would like to express my cordial and faithful gratitude to Prof. Dr. Brian Ogle, my main supervisor, for his kind support, professional guidance, and valuable advice in many different ways.
          

5. References

Bach Knudsen, K.E., 1997. Carbohydrate and lignin contents of plant materials used in animal feeding. Animal Feed Science and Technology 67: 319-338.

Bach Knudsen, K.E., 2001. The nutritional significance of "dietary fibre" analysis. Animal Feed Science and Technology 90: 3-20.

Bedford, M.R., 1995. Mechanism of action and potential environmental benefits from the use of feed enzymes. Animal Feed Science and Technology 53: 145-155.

Bhat, M.K. and Hazlewood, G.P., 2001. Enzymology and other characteristics of cellulases and xylanases. In: Enzymes in farm animal nutrition, Eds: Bedford, M.R. and Partridge, G.G. CABI publishing, Wallingford, pp. 11-60.

Chabeauti, E., Noblet, J., Carré, B., 1991. Digestion of plant cell walls from four different sources in growing pigs. Animal Feed Science and Technology 32: 207-213.

Chinh, B. V., Oanh, B. T., Ha, N. N., Viet, T. Q., Khang, D. T., Tinh, N. T., 2001. Chemical Composition and Nutritive Value of Animal Feeds in Vietnam. Agricultural Publishing House, Hanoi.

Country Report of Vietnam for FAO’s State of the World’s Animal Genetic Resources. 2003.

Department of Livestock Production, Ministry of Agriculture and Rural Development, 2006. Report of livestock production from 2001 to 2005 and orientation of livestock production from 2006 to 2015. Ba Dinh printing Company, Ministry of Public Security.

Diebold, G., Mosenthin, R., Piepho, H.-P., Sauer, W.C., 2004. Effect of supplementation of xylanase and phospholipase to a wheat-based diet for weaning pigs on nutrient digestibility and concentrations of microbial metabolites in ileal digesta and feces. Journal of Animal Science 82: 2647-2656.

Dierick, N.A. and Decuypere, J.A., 1994. Enzymes and growth in pigs. In: Principles of pig science, Eds: Cole, D.J.A., Wiseman, J. and Varley, M.A. Nottingham University Press. pp. 169-195.

Dierick, N.A., Vervaeke, I.J., Demeyer, D.I., Decuypere, J.A., 1989. Approach to the energetic importance of fibre digestion in pigs. I. Importance of fermentation in the overall energy supply. Animal Feed Science and Technology 23: 141-167.

Dung, N.N.X., Manh, L.H., Uden, P., 2002. Tropical fibre sources for pigs-digestibility, digesta retention and estimation of fibre digestibility in vitro. Animal Feed Science and Technology 102: 109-124.

Duyet, H. N. and Duong, N. K., 1996. Pig breeding in central Vietnam and its improvement. In: Exploring approaches to research in the animal sciences in Vietnam: A workshop held in the city of Hue, Vietnam 31 July - 3 August, 1995. Canberra, Australia.

FAOSTAT, 2003. FAO statistical Database. Food and Agriculture Organization of the United Nations. Rome. http://faostat.fao.org/default.jsp.

Fernadez, J. and Jørgensen, J.N., 1986. Digestibility and absorption of nutrients as affected by fibre content in the diet of the pig. Quantitative aspects. Livestock Production Science 34: 53-71

Fernando, R. and Feuchter, A., 2004. A review of the nutrition and growth of the suckling pig by providing creep feeding supplementation to reduce piglet mortality and minimize post-weaning syndrome. http://www.agrogea.com/docs/lecho/lecho_creep1.htm

Fevrier, C., Bourdon, D.,Aumaitre, A., 1992. Effects of level of dietary fibre from wheat bran on digestibility of nutrients, digestive enzymes and performance in the European Large White and Chinese Meishan pigs. Journal of Animal Physiology and Animal Nutrition 68: 60-72.

Freire, J.P.B., Guerreiro, A.J.G., Cunha, L.F., Aumaitre, A., 2000. Effect of dietary fibre source on total tract digestibility, caecum volatile fatty acids and digestive transit time in the weaned piglet. Animal Feed Science Technology 87: 71-83.

Freire, J.P.B., Dias, R.I.M., Cunha, L.F., Aumaitre, A., 2003. The effect of genotype and dietary fibre level on the caecal bacterial enzyme activity of young piglets: digestive consequences. Animal Feed Science and Technology 106: 119-130.

Gdala, J., Johansen, H.N., Bach Knudsen, K.E., Knap, I.E., Wagner, P., Jørgensen, O.B., 1997. The digestibility of carbohydrates, protein and fat in the small and large intestine of piglets fed non-supplemented and enzyme supplemented diets. Animal Feed Science and Technology 65: 15-33.

Giang, H.H., 2003. Processing and utilization of sweet potato vines and roots for F1 crossbred fattening pigs. MSc thesis, Swedish University of Agricultural Sciences.

Graham, H., Hesselman, K., Åman, P., 1986a. The influence of wheat bran and sugar-beet pulp on the digestibility of dietary components in a cereal-based pig diet. Journal of Nutrition 116: 242-251.

Graham, H., Hesselman, K., Jonsson, E., Åman, P., 1986b. Influence of β-glucanase supplementation on digestion of a barley-based diet in the pig gastrointestinal tract. Nutrition Reports International 34: 1089-1096.

Graham H., Löwgren W., Pettersson D., Åman P., 1988. Effect of enzyme supplementation on digestion of a barley/pollard-based pig diet. Nutrition Reports International 38: 1073-1079.

Graham, H., Fadel, J.G., Newman, C.W., Newman, R.K. 1989. Effect of pelleting and glucanase supplementation on the ileal and fecal digestibility of a barley-based diet in the pig. Journal of Animal Science 67: 1293-1298.

Hai, L. T. and Nguyen, N. H., 1997. Outlines of pig production in Vietnam. Pig News and Information 18: 91-94.

Henry, Y., 1976. Prediction of energy values of feeds for swine from fibre content. In: P. V. Fonnesbeck, P. V. Harris, L. C. Kearl (eds), Proceedings of the First International Symposium on Computerization of Diets, 11-16 July 1976, Utah State University, Logan, UT, pp. 270-281.

Högberg, A., 2003. Cereal non-starch polysaccharides in pig diets: Influence on digestion site, gut environment and microbial populations. Doctoral thesis, Swedish University of Agricultural Sciences, Uppsala 2003.

Högberg, A. and Lindberg J. E., 2004. Influence of cereal non-starch polysaccharides and enzyme supplementation on digestion site and gut environment in weaned piglets. Animal Feed Science and Technology 116: 113-128.

Iiyama, K., Lam, T.B.T., Stone, B.A., 1994. Covalent cross-links in the cell wall. Plant Physiology 104: 315-320.

Inborr, J. and Graham, H., 1991. The effect of enzyme supplementation of a wheat/barley-based starter diet on nutrient feacal digestibility in early weaned pigs. Animal Production 52: 565 (abstract).

Jensen, M.S., Bach Knudsen, K.E., Inborr, J., Jakobsen, K., 1998. Effect of beta-glucanase supplementation on pancreatic enzyme activity and nutrient digestibility in piglets fed diets based on hulled and hulles barley varieties. Animal Feed Science and Technology 72: 329-345.

Jørgensen, H., Zhao, X., Eggum, B. O., Zhao, X. Q., 1996. The influence of dietary fibre and environmental temperature on the development of the gastrointestinal tract, digestibility, degree of fermentation in the hindgut and energy metabolism in pigs. The British Journal of Nutrition 75: 365–378.

Khieu Borin, Lindberg, J.E., Ogle B., 2005. Effect of variety and preservation method of cassava leaves on diet digestibility by indigenous and improved pigs. Journal of Animal Science 80: 319-324.

Kemp, B., Hartog, L. A. den, Klok, J. J., Zandstra, T., 1991. The digestibility of nutrients, energy and nitrogen in Meishan and Dutch Landrace pigs. Journal of Animal Physiology and Animal Nutrition 65: 263-266.

Kinh, L.V. and Hai, N.T., 2006. Improvement of pig performance through breeding and feeding in Vietnam
www.aphca.org/workshop/pigWS_nov2006/files_pdf/Vietnam_PigPerformance_       Nov06.pdf

Lapar, M. L., Binh, V. T., Ehui, S., 2003. Identifying barriers to entry to livestock input and output market in Southeast Asia. www.fao.org/ag/againfo/resources/en/publications/sector_reports/lsr_VNM.pdf

Le Goff, G., Noblet J., Cherbut, C., 2003. Intrinsic ability of the faecal microbial flora to ferment dietary fibre at different growth stages of pigs. Livestock Production Science 81:75-87.

Le Goff, G., Dubois, S., Van Milgen, J., Noblet, J., 2002a. Influence of dietary fibre level on digestive and metabolic utilisation of energy in growing and finishing pigs. Animal Research 51:245-259.

Le Goff, G., Van Milgen J., Noblet, J., 2002b. Influence of dietary fibre on digestive utilisation and rate of passage in growing pigs, finishing pigs and adult sows. Journal of Animal Science 74:503-515.

Lekule, F.P., Jørgensen, H., Fernandez, J., Just, A., 1990. Nutritive value of some tropical feedstuffs for pigs. Chemical composition, digestibility and metabolizable energy content. Animal Feed Science Technology 28: 91-101.

Len, N. T., Lindberg, J. E., Ogle, B., 2006a.  Digestibility and nitrogen retention of diets containing different levels of fibre in local (Mong Cai), F1 (Mong Cai x Yorkshire) and exotic (Landrace x Yorkshire) growing pigs in Vietnam. Journal of Animal Physiology and Animal Nutrition (In press).

Len, N. T., Lindberg, J. E., Ogle, B., 2006b. Effect of dietary fibre level on the performance and carcass traits of Mong Cai, F1 Crossbred (Mong Cai x Yorkshire) and Landrace x Yorkshire Pigs. (In press)

Len, N. T., Hong, T.T.T., Lindberg, J. E., Ogle, B., 2007. Comparision of total tract digestibility, development of visceral organs and digestive tract of Mong Cai and Yorkshire x Large White piglets fed diets with different fibre sources. (In  manus)

Lemke, U., Thuy, L. T., Valle Zárate, A., Kaufmann, B. 2000. Characterisation of a model for conservation of autochthonous pig breeds on smallholder farms in North Vietnam. Project report for GTZ/ Sectoral Project: Tropical Ecology Support Program TOEB. Stuttgart, Germany.

Li, S., Sauer, W.C., Mosenthin, R., Kerr. B., 1996. Effect of beta-glucanase supplementation of cereal diets for starter pigs on the apparent digestibilities of dry matter, crude protein and energy. Animal Feed Science Technology 59: 223-231.

Lindberg, J.E. and Andersson, C., 1998. The nutritive value of barley-based diets with forage meal inclusion for growing pigs based on total tract digestibility and nitrogen utilization. Livestock Production Science 56: 43-52.

Li W. F., Feng, J., Xu Z.R., Yang, C.M., 2004 Effects of non-starch polysaccharides enzymes on pancreatic and small intestinal digestive enzyme activities in piglet fed diets containing high amounts of barley. World Journal Gastroenterol 10(6): 856-859.

Loc, N. T., Ogle, B., Preston, T. R. 1996. Pig production in Central Vietnam: results of a participatory rural appraisal survey and on-farm feeding trials with protein supplementation of traditional diets. Integrated farming in Human development. Proceedings of a workshop. March 25 – 29, 1996. Tune Landboskole, Denmark.

Ly, L. V. 2000. The development of a sustainable animal production system based on the advantage of tropical agriculture. Workshop-seminar ''Making better use of local feed resources'' January, 2000. SAREC-UAF, Hanoi, Vietnam.

Ly, J., Dieguez, F.J., Martinez, R.M., Garcia, A., 1998. Digestion of a diet very high in fibre in Cuban Creole pigs. Animal Feed Science Technology 72: 397-402.

Morales, J., Perez, J.F., Martin-Orue, S.M., Fondevila, M., Gasa, J., 2002. Large bowel fermentation of maize or sorghum-acorn diets fed as a different source of carbohydrates to Landrace and Iberian pigs. The British Journal of Nutrition 88: 489-498.

Medel, P., Baucells, F., Gracia, M.I., Blas C. de, Mateos, G.G., 2002. Processing of barley and enzyme supplementation in diets for young pigs. Animal Feed Science and Technology 95: 113-122.

Ndindana, W., Dzama, K., Ndiweni, P.N.B., Maswaure, S.M., Chimonyo, M., 2002. Digestibility of high fibre diets and performance of growing Zimbabwean indigenous Mukota pigs and exotic Large White pigs fed maize based diets with graded levels of maize cobs. Animal Feed Science Technology 97: 199-208.

Noblet, J. and Le Goff, G., 2001. Effect of dietary fibre on the energy value of feeds for pigs. Animal Feed Science and Technology 90: 35-52.

Omogbenigun, F.O., Nyachoti, C.M., Slominski, B.A., 2004. Dietary supplementation with multienzyme preparations improves nutrient utilization and growth performance in weaned pigs. Journal of Animal Science 82:1053-1061.

Officer, D.I., 1995. Effect of multi-enzyme supplements on the growth performance of piglets during pre- and post-weaning periods. Animal Feed Science and Technology 56: 55-65.

Partridge, G., 2001. The weaner pig - enzymes and biotechnology for the future. In: The weaner pig. Nutrition and management, Eds: Varley, M.A. & Wiseman, J. CABI Publishing, Wallingford, pp. 123-152.

Rainbird, A. L. and Low, A. G., 1986. Effect of various types of dietary fibre on gastric emptying in growing pigs. The British Journal of Nutrition 55: 111-12.

 Rodríguez, J. L., Preston, T. R., Dolberg, F., Petersen, P. H., 1997. Participatory rural development: Experiences in Binh Dien and Xuan Loc villages in Central Vietnam. Integrated Farming in Human Development, Denmark, 25-29, March, 1996. pp. 161-196.

Suga, Y., Kawai, M., Noguchi, S., Shimura, G., Samejima, H., 1978. Application of cellulolytic and plant tissue macerating enzyme of Irpex lacfeus Fr. as feed additive enzyme. Agricultural Biology Chemistry 42: 347-350.

Tangendjaja, B., Johnson, Z.B., Noland, P.R., 1988. Effect of cooking and addition of enzymes on feeding value of rice bran for swine. Nutrition Reports International 37(6): 449-458.

Thacker, P.A., McLeod, J.G., Campbell, G.L., 2002. Performance of growing-finishing pigs fed diets based on normal or low viscosity rye fed with and without enzyme supplementation. Archives of Animal Nutrition 56(5): 361-370.

Thien, N., Van, P. T., Le,  P. N., Doanh, P. H., Nghi, N., Quac, N. K., Hot, V. T., 1996. Improvement of productivity and meat quality of pigs in the Red River Delta region by crossbreeding. ACIAR, Canberra, Australia.

Thien, N. (2002). The results of research and development of pig crossbreds with high performance and high quality in Vietnam. In: National Institute of Animal Husbandry - Over 50 years established and development. Agricultural Publishing House. Vietnamese.

Thomke, S. and Elwinger, K., 1998. Growth promotants in feeding pigs and poultry. III. Alternatives to antibiotic growth promotants. Annales zootechnie 47: 245-271.

Thuan, N. T., Kai, S., Yutaka, T., 2000. An overview on pig production and pork market in the Red River Delta in Vietnam. Journal of the Faculty of Agriculture, Kyushu University 5:325-334.

Vervaeke, I.J., Dierick, N.A., Demeyer, D.I., Decuypere, J.A. 1989. Approach to the energetic importance of fibre digestion in pigs: II an experimental approach to hindgut digestion. Animal Feed Science Technology 23: 169-19.

Van, P. T., Tra, H. T. H., Ngoc, L. T. K. and Dung, T. H., (2001). Crossbreds among Landrace, Yorkshire and Duroc under different management methods. In: Science papers on animal production - National Institute of Animal Husbandry from 1999-2000. pp. 56-63.

Xia Meisheng, 2000. Effect of NSP enzyme on performance of growth and digestion for growing pigs fed paddy-based diets. Journal of Zhejiang University (Agriculture and Life Sciences) 26: 559-562.

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