Introduction

In recent years, the pig production in the Mekong delta has been reducing because of the increases in animal feed costs that have caused lower economic returns for smallholder farmers. Many feed factories in the towns offer expensive concentrates for pigs in the remote areas. This has contributed to the development of unsuitable feeding systems for pigs in the region. The development of feeding systems has to be based on locally available and cheap feed resources.

Rice distillers’ by-product is the waste when rice is fermented and then distilled to produce alcohol in an artisan production system.  Rice is cooked and yeast is added to the cooked rice for fermentation. The alcohol is distilled from the fermentation liquor, after which the waste “hem” is used as a wet feed for pigs. Rice distillers’ by-product (hem) is produced in large amounts in some places in the Mekong delta. This by-product is cheap, very palatable for pigs and available all year round. Using “hem” for fattening pigs is a way for the farmers to get better economic returns. Typical diets for growing pigs are based on rice bran or concentrate, “hem” and vegetables. Sometimes the farmers exclude “hem” from the diet, which results in environmental pollution because the “hem” is dumped in the river.

The rice distillers by-product ”Hem” is palatable and has a fairly high protein content (20% crude protein in dry matter) of good quality with approximately 3.9 g lysine/16 g N (Manh Huu Luu et al 2000)). In addition it is a good source of B-vitamins.

The aim of the research reported in this paper was to determine the optimum level of  rice distillers by-product ”Hem” in diets for growing-finishing pigs.
 

Materials and Methods

The study was conducted at the experimental farm of the Animal Science Department, Cantho University. 

Animals and treatments

Thirty growing Yorkshire pigs of 20 ± 1 kg live weight were allocated according to a completely randomized design into five different diets (levels of "Hem"). The treatments were: Basal diet (control), and 4 experimental diets in which "Hem" replaced 25, 50, 75 or 100% of the protein provided by fish meal in the basal diet (details of ingredients and diets are in Tables 1, 2 and 3). In a parallel experiment, thirty finishing pigs (59± 2 kg) were used in a similar design to measure effects of "Hem" on carcass quality.  All animals were individually housed. They were de-wormed and vaccinated before starting the experiments.

Feeds and diets

"Hem" was purchased every day from a local rice wine producer.  Fish meal, rice bran and broken rice were purchased at the same time from a local feed company. The control diets were formulated to contain 17% of crude protein in DM in the growing and 15% in the finishing stage. The daily allowance was set at 4% of live weight given in two feeds at 9:00 and 14:00 h.  Refusals were recorded every meal to measure feed intake. Water was available throughout the experiment.

Measurements

The pigs were weighed every 3 weeks and two pigs of each treatment (finishing phase) were slaughtered to measure carcass quality at the end of the trial. Feed ingredients and diets were analysed for proximate composition by AOAC (1984) procedures. 

Chemical analysis

Feed samples were analysed in duplicate for dry matter (DM), crude protein (CP), ash, ether extract (EE) according to the standard procedures (AOAC 1984).  

Statistical analysis

All data were analysed by analysis of variance using the General Linear Model option of the Minitab software (version 13).The model used was the following:

Xi = μ + Ti + e     where,

Xi is the individual observation, μ the overall mean, Ti treatment effect (i=1 - 4) and e is residual error. If the treatment effect was significant (P<0.05), differences between means were tested with the Tukey procedure of the Minitab software.

Results and discussion

There were no differences in any of the performance parameters between the diets (Table 5).

The results indicate that the protein quality of  "Hem" is comparable with that of the local fish meal, and that it can therefore replace completely the fishmeal in diets for growing / fattening pigs. However, the quality of Hem is quite good,  as the mean lysine content was found to be 3.91g/16g N (Manh Huu Luu et al 2000). Some studies have been carried out  by Harmon (1974, 1975) and Cromwell et al 1993) indicating that distiller’s dried grain with solubles (DDGS) was a good source of lysine for swine. The fact that local farmers use rice bran supplemented with "Hem" as the sole diet for pigs also indicates that the protein quality of "Hem" is high.

There were no apparent differences in carcass traits for pigs receiving the different levels of "Hem" (Table 6), which is is line with the good results for the performance traits.