Enzyme supplementation increases digestibility and N balance in growing pigs fed rice bran and ensiled taro foliage

Chhay Ty, Khieu Borin and T R Preston*

Center for Livestock and Agriculture Development.
Pras Teat village, Rolous commune, Kandal Stung district, Kandal province.
PO Box 2423 Phnom Penh 3, Cambodia
chhayty@celagrid.org
* Center for Research and Technology Transfer, Nong Lam University, Ho Chi Minh City, Vietnam

Abstract

The aim of this study was to evaluate the effect of enzyme supplementation on digestibility and N balance in growing pigs fed fiber-rich diets based on rice bran and ensiled foliage of Taro (Colocacia esculenta). Eight crossbred (Large White x Local) castrate male pigs weighing 30.2±0.80 kg were allotted to a 2*2 factorial arrangement of four treatments in a double Latin Square. Each experimental period was of 12 days with collection of feces, urine and feed residues on the last 5 days of each period. The first factor was with or without enzyme supplementation and the second was grade of rice bran (fine or coarse). 

The fine rice bran was higher in crude protein (CP)  and lower in crude fiber (CF) than the coarse bran. Intakes of DM, taro foliage and CP were increased by enzyme supplementation on the coarse bran diet but there was no effect of enzyme in the diets with fine bran. Overall intakes were higher for fine than for coarse bran diets.   The apparent digestibilities of DM, OM, CP and CF were higher for fine rice bran diets compared with coarse rice bran. On the coarse bran diet enzyme supplementation increased the digestibiliity of DM, OM, CP and CF but had no effect in the diets based on fine rice bran.  N retention was increased by enzyme supplementation and by using fine compared with coarse rice bran.  There were no interactions among the treatments.

It was concluded that the nutritive value of rice bran-ensiled taro foliage diets for growing pigs is enhanced by supplementation with a mixed enzyme preparation and that the effect is greater on diets with higher content of crude fiber.

Key words: Taro foliage, fine rice bran, coarse rice bran, enzyme

Introduction

The main feed ingredient used by small scale farmers in Cambodia for raising pigs is rice bran, which is available throughout the country as a by-product from rice milling. It is rich in fiber and in non-starch polysaccharides (NSP) (Len et al (2007). These substances are indigestible in the small intestine but in the large intestine a variable fraction  will be fermented to short-chain fatty acids and thereby serve as a source of energy for the host (Lindberg 2014).  Lack of enzymatic capacity might be compensated for by supplementation of the diet with exogenous enzymes. The effect of using feed enzymes as supplements to pig diets has been investigated by several researchers, with promising results, as it was found that enzyme supplementation improved nutrient digestibility and growth performance, especially after weaning (Jensen et al 1998; Medel et al 2002;). Högberg and Lindberg (2004) also showed that, in weaned piglets, the supplementation of diets rich in fiber and NSP with  fibre-degrading enzymes increased organic acids in the ileum, ndicating an enhanced digestibility of fiber in the small intestine.

Objective

The aim of this study was to evaluate the effect of enzyme supplementation on digestibility and N balance in growing pigs fed fiber-rich diets based on rice bran and ensiled foliage of Taro (Colocacia esculenta).

Materials and Methods

Location

The experiment was carried out at the Center for Livestock and Agriculture Development (CelAgrid) located in Prah Theat village, Sangkat Rolous, Khan Dangkor, approximately 25 km from Phnom Penh city.

Treatments and design

The experimental design was a 2*2 factorial arrangement of 4 treatments within a double Latin square (Table 1).

The factors were:

• Enzyme supplementation or none
• Fine or coarse grade of rice bran

The planned composition of the diets and the calculated proximate composition is shown in Table 2.

Experimental feeds and feeding

Fine rice bran was purchased from a  modern rice mill, near Phom Penh city; coarse rice bran was purchased from a small rice mill in a nearby village. Taro foliage was harvested from natural ponds close to CelAgrid. Enzyme (Kemzyme V Dry) is a Malaysian product and was bought from an animal feed company in Phnom Penh, the cost of Kemzyme V Dry is 4.56$/kg. The enzyme (Kemzyme V Dry; contains Alpha amylase, Protease, Xylanase and Cellulase; © PT. Satwa Jawa Jaya, Indonesia) was used at a level of 5g/kg of the diet on DM basis. The taro foliage (leaves and stems) was chopped by hand in small pieces (about 2-3cm) and dried one-two days under sunlight in order to reduce the moisture content and then ensiled without adding any other ingredient and stored for one month before feeding to the pigs

The pigs were fed thrice daily with equal rations at 8:00 am, 12:00 am and 5:00 pm. Rice bran, salt; premix and enzyme were mixed together and offered first at levels equivalent to 20 g DM/kg body. Similar amounts of ensiled taro foliage (as DM) were then offered. Water was permanently supplied through low pressure nipples. The animals were weighed at the beginning of the trial and every 12 days.

Pigs and cages

Eight castrated male crossbred pigs (Large white x Local breed) of live weight 30.2±0.80 kg were housed in metabolism cages during the whole trial (48 days).

Data collection

Samples of feeds offered, refusals, urine and feces were collected every day and 5% of the amount  was stored at -4⁰C until the end of each collection period of 5 days. A representative sample obtained from every treatment were mixed thoroughly by hand and then homogenized in a grinder for analysis of DM, OM, CP and CF. Urine was collected in a plastic bucket to which sulphuric acid was added to maintain the pH below 4.0 (20ml of concentrated H₂SO₄). The volume of urine was measured every day and 5% of the volume stored at -4⁰C until the end of each period, when a sample was taken for analysis of N.

Chemical analyses

The DM content was determined by micro-wave radiation (Undersander et al 1993);  ash, CP (N*6.25) and CF were determined according to AOAC (1990). All analyses were performed in duplicate and were presented on a DM basis.

Statistical analyses

Analysis of variance was performed according to a double 4*4 Latin-square design using the general linear models of Minitab software (Minitab 2010). Sources of variation were enzyme, grade of rice bran, interaction between enzyme*grade of rice bran, animal, period and error. The model used was:

Y_ijkl= μ + E_i + L_j + E_i*L_j + A_k + P_{l +} e_ijkl

where Y = Dependent variable

μ = Overall mean

E_i = Enzyme effect

L_{j =} Rice bran grade

E_i*L_j = Interaction enzyme*rice bran grade

A_k = Animal effect

P_l = Period effect

e_ijkl = Random error

Results and discussion

Chemical composition

The fine rice bran was higher in CP and lower in CF than the coarse bran (Table 3). The chemical composition of the two grades of rice bran was similar to that reported by Chhay Ty et al (2009) who sieved rice bran by passing it through a plastic net with holes of 1 mm, to separate the fine and coarse particles.  The CP content of ensiled taro foliage was similar to that reported by Chhay Ty et al (2010).

Feed intake

The ensiled taro foliage accounted for about 50% of the diet DM (Table 4).

There were interactions between grades of rice bran and enzyme supplementation on intake (Table 5). Intake of DM, taro foliage and CP were increased by enzyme supplementation on the coarse bran diet but there was no effect in the diets with fine bran. However, overall intakes were higher for fine than for coarse bran diets.

Fecal characteristics in pigs

The feces from the coarse rice bran diets were higher in DM and fiber and lower in nitrogen compared with those from the fine rice bran diets (Table 6). The concentration of nitrogen was lower in feces from the enzyme supplemented diets. The excretion of DM and water per unit DM intake was higher for coarse bran diets, and with tendencies to be higher in diets without enzyme supplement.

Digestibility coefficients

The apparent digestibilities of DM, OM, crude protein and crude fibre were higher in fine rice bran diets compared with coarse rice bran (Table 7). These effects of dietary fiber level are well documented (Ndindana et al 2002; Giang et al 2003; Len et al 2007; Tran Thi Bich Ngoc et al 2007).

Enzyme supplementation did not affect apparent digestibility of DM)  but increased that of crude protein and crude fiber.  This result is similar to those reported by Medel et al (2002), Jensen et al (1998) and Högberg and Lindberg (2004).

There were interactions between type of rice bran and enzyme supplementation (Table 8). On the coarse bran diet enzyme supplementation increased the digestibiliity of DM, OM, crude protein and crude fibre but had no effect in the diets based on fine rice bran. 

N balance

N retention was increased by enzyme supplementation and using fine compared with coarse rice bran (Table 9).  There were no interactions among the treatments 

Conclusions

• There were interactions between fibre level in the diet and the effect of adding a commercial mixed enzyme preparation (contained amylase, protease, xylanase and celulase); on coarse bran diets, the enzyme supplement increased feed intake, and apparent digestibility coefficients but had no effect on these parameters in diets based on fine bran. 

• Feed intake, digestibility coefficients and N retention were always better in pigs fed fine rather than coarse bran in the diet.

• N retention was higher in pigs fed fine rather than coarse rice bran and was always better when the mixed enzyme was added to the diet.

Acknowledgements

The authors would like to express their gratitude to the MEKARN project financed by Sida and to the Center for Livestock and Agriculture Development (CelAgrid), for providing resources for conducting this experiment.

References

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Received 11 March 2013; Accepted 10 March 2014; Published 5 April 2014

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