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, Ninh Thi Len and Brian Ogle*

Department of Animal Nutrition, National Institute of Animal Husbandry,
Hanoi, Vietnam
bichngocniah75@hotmail.com
* Department of Animal Nutrition and Management,
Swedish University of Agricultural Sciences, Uppsala, Sweden

Abstract

The present study was conducted to investigate the effects of enzyme supplementation of a high fibre diet on the performance of local (Mong Cai) and exotic (Landrace x Yorkshire) piglets. Twenty four weaned piglets from two breeds (4.2 ± 0.4 kg for Mong Cai and 7.5 ± 0.4 kg for Landrace x Yorkshire), with an equal number of males and females, were used in this experiment. An enzyme mixture added to the high fibre diet included a-amylase, b-glucanase, cellulase and protease. The experiment was done according to a 2 x 2 factorial completely randomized designed, with six replicates.

The results show that in the post-weaning period the enzyme supplement increased average daily gain by 11.6% (P<0.01)  and decreased feed conversion ratio by 12.5% (P<0.05) compared with the diet without enzyme supplementation, whereas enzyme supplementation had no effect in growing pigs (P>0.05). Average daily feed intake was not influenced by enzyme supplementation. The Mong Cai had higher feed and nutrient intake per kg live weight (P<0.01) than Landrace x Yorkshire, but lower average daily gain and feed conversion ratio (P<0.001).  

Keywords: enzyme supplementation, piglets, breed, post-weaning, growing period

Introduction

In Vietnam, pigs are mainly kept on smallholder farms and raised in traditional systems. Typically, smallholder farmers in the Northern provinces keep one to three pigs (Lich and Tuyen, 2001). The main feed ingredients used in diets for pigs are local feedstuffs, which are cheap and available in large amounts. These feeds are suitable for small farmers who cannot afford the inputs for intensive pig production. The main nutritional characteristics of these local feeds are high fibre, and sometimes relatively high protein content. Recently, Len et al (2006) showed that a high fibre content in the diet has negative effects on energy and dietary component digestibility in growing pigs, and also reduces nitrogen retention as a proportion of nitrogen intake. The degradation and absorption of dietary fibre in the small intestine may be limited by a lack of appropriate enzymes. Theoretically, exogenous enzymes can enhance this degradation. Several studies have investigated the performance responses of pigs to enzyme supplements, and most of these have recorded improved daily gain and feed conversion ratios. Recent data reported in a review by Liu and Baidoo (1997) showed that feed conversion and growth rate in response to enzyme supplementation was age related, with improvements on average being 10% for pigs of 8–20 kg, 5.3% for pigs of 20–40 kg and 3% for pigs of 40–60 kg.

There is some evidence that local  and F1 crossbred pigs  are better able to utilize high fibre diets than exotic breeds (Ndindana et al 2002; Qin et al 2002). In studies carried out in Southeast Asia, the Mong Cai breed was shown to digest energy and dietary components more efficiently than improved and exotic pigs (Len et al 2006; Khieu Borin et al 2005).  However, due to the low live weight gain and poor meat quality, as well as the high carcass fat content of some local breeds (such as the Mong Cai) exotic and F1 breeds are normally reared for meat in the rural areas of Northern Vietnam, even in semi-intensive smallholder systems, although nucleus Mong Cai herds are kept to produce breeding stock.

 The present study was carried out to investigate the effects of enzyme supplementation of a high fibre diet on the performance of local (Mong Cai) and exotic (Landrace x Yorkshire) piglets post-weaning.

Material and methods

Location

 The experiment was conducted at the Station of Research and Testing of Animal Feeds, National Institute of Animal Husbandry, Hanoi, Vietnam, between July and October, 2006.

 Animals and management

The animals in the experiment were piglets, weaned at 28 days of age, bought at the Pig Research Center, Hanoi and Quang Ninh Province. The breeds were local Mong Cai (MC) and exotic Landrace x Yorkshire (LY). The mean body weight at 30 days of age was 7.5 ± 0.4 kg for the LY and 4.2 ± 0.4 kg for the MC. Before the start of the experiment, the piglets were vaccinated against Cholera, Pasteurellosis, Pneumonia and Paratyphoid. The piglets were fed ad libitum during the experimental period. The feed was provided in troughs and water was supplied ad libitum by automatic water nipples. The pens and troughs were cleaned every day.

Experimental feeds

 The diets used were the same as the high fibre diets used in a previous digestibility experiment (Ngoc et al 2007). The diets were based on maize meal, fish meal, soybean meal, soybean oil, rice bran and cassava residue meal, and were calculated to contain 200 g NDF kg^-1 DM in the first period (post-weaning) and 280 g NDF kg^-1 DM in the second period (growing). The diets were formulated to have equal contents of metabolisable energy, crude protein and the most important amino acids. An enzyme mixture was included at a level of 1 g/kg of the diet, as fed. The enzyme mixture was supplied by the Kemin Industries (Asia) Pte Ltd company (Singapore) and included a-amylase (788 units/g), b-glucanase (5602 units/g), cellulase (9007 units/g) and protease (922 units/g).

Maize meal, fish meal, soybean meal, soybean oil and rice bran were bought from the Station of Research and Testing of Animal Feeds, NIAH, Hanoi. Cassava residue was bought in Hoai Duc district, Ha Tay Province, and stored in plastic bags to avoid moisture entering. The diets were mixed every 7 days and put into plastic bags in order to maintain the quality of the feed and avoid mould.

The diets were formulated based on requirements according to NRC (1998) and divided into two periods, from 30 - 60 days of age and from 60 - 120 days of age. The chemical composition of the feed ingredients and diets is shown in Table 1 and 2.

Experimental design

The feeding trial was done according to a 2 x 2 factorial completely randomized design, with two breeds (MC and LY) and a diet with or without enzyme supplementation. A total of 24 weaned piglets from two breeds (12 MC and 12 LY) from 2 litters of each breed, with an equal number of males and females, was used in the experiment. The piglets were allowed two days for adaptation to the new feed before the experiment started, and were randomly allocated into 24 individual pens. The piglets from different litters were distributed equally among the treatments. Each treatment thus consisted of 6 pens, and each pen was a replicate. The experiment lasted 90 days.

Measurements and data collection

Feed offered and feed refusals were recorded daily. The animals were weighed in the morning before feeding at the beginning, at 60 and 90 days of age, and at the end of the experiment. The measurements recorded were as follows:

• Growth rate (g/head/day)

• Daily feed intake (kg/head/day)

• Feed conversion ratio (kg feed/kg weight gain)

Chemical analysis

Samples of feed and refusals were taken weekly and stored in sealed plastic bags, and then mixed together monthly for dry matter analysis.

Diets were analysed for dry matter (DM), crude protein (CP), crude fibre (CF), ether extract (EE) and ash according to standard AOAC methods (AOAC, 1990), and neutral detergent fibre (NDF) was determined by the method of Van Soest et al (1991). 

Statistical analysis

The data were analyzed statistically by using the GLM procedure of Minitab Software, version 13.31 (Minitab, 2000). Treatment means which showed significant differences at the probability level of P<0.05 were compared using Tukey’s pairwise comparison procedures.

     The mathematical model was:

      Y = M + B_i + D_j + (B_i x D_j) + e

      Where:

      Y = Dependent variable

      M = Overall mean

      B_i = Effect of breed i

      D_j = Effect of enzyme mixture j

      (B_i x D_j) = Interaction between breed i and enzyme mixture j

      e = Error

Results

Feed and nutrient intakes are presented in Table 3. Daily DM, CP and NDF intakes in each period and overall were not significantly different between diets (with or without enzymes), and there was no interaction between breed and diet. However, the MC had significantly higher intakes of DM, CP and NDF in both periods and overall (P < 0.01) when expressed as a proportion of metabolic body weight. Mean DM, CP and NDF intakes over the whole experimental period in the MC were 125, 29.5 and 23.5 g/kg BW^0.75/day, respectively, and in the LY were 97.0, 21.5 and 21.0 g/kg BW^0.75/day, respectively.