Local feed resources as replacement for soybean meal in diets for growing Moo Lath pigs

Bounlerth Sivilai, Duangmany Volachith, Anusin Phompakdee¹, Malavanh Chittavong and T R Preston²

Department of Livestock and Fisheries, Faculty of Agriculture, National University of Laos, Vientiane Capital, Lao PDR
lerth_si@yahoo.com
¹ Technical-vocational school, Division of Livestock and Fishery, Bokeo Province, Laos PDR
² Centro para la Investigación en Sistemas Sostenibles de Producción Agropecuaria (CIPAV, Carrera 25 No 6-62 Cali, Colombia

Abstract

The aim of the research was to investigate available protein sources as replacement for soybean meal in diets of Moo Lath pigs. Sixteen growing Moo Lath pigs with average live weight of 12.3 ± 0.7 kg were housed in individual pens and assigned to four treatments replicated four times, according to a completely randomized design. The treatments were: soybean meal (SBM), rice distillers’ byproduct (RDB), brewers’ grains (BG) and ensiled taro foliage (ETF).

Dry matter intake, live weight gain and feed conversion were similar for RDB and SBM and superior to these traits in pigs fed BG and ETF as sources of protein. It is concluded that RDB can replace soybean meal in diets of growing Moo Lath pigs with no loss in performance

Key words: brewers’ grain, cassava, Colocasia esculenta, import substitution, protein, rice distillers’ byproduct, taro

Introduction

Replacing maize and soybean imports to developing countries is one way of responding to the emergencies of climate change and global loss of biodiversity (LRRD mission 2020). Two issues that have to be considered are: (i) availability of local resources to replace maize and soybean which are the basis of pig feeds globally; and (ii) strategies to make better use of the feed resources that are locally available but which may be of lower nutritional value than maize and soybean. In tropical countries, a potential alternative as an energy source is cassava root; while protein can be sourced locally as byproducts of industrial beer production (brewers’ grains) and locally-produced rice “wine” (rice distillers’ byproduct). Of the vegetative sources of protein, taro (Colocacia esculenta) is high-yielding (Sivilai et al 2016; Hang et al 2018) and highly digestible by Moo lath pigs (Sivilai and Preston 2017) and Mong Cai pigs (Malavanh et al 2006).

Of the issues to be considered in such a strategy, the choice of breed is an important factor. Native pigs in Vietnam (Mong Cai) were shown to be better adapted to diets based on forages than were pigs of the genetically superior “Large White” (Duyet et al 2010; Rodríguez and Preston 1996). The popularity of the indigenous Moo Lath breed by small-scale farmers in Laos is another indication of “superior” adaptation to feeding systems based on local resources (Sivilai et al 2016, 2019)

The following experiment was designed to respond to the above mentioned issues by evaluating locally available protein sources as replacement for soybean meal in diets of growing Moo Lath pigs.

Materials and methods

Experimental design

Sixteen growing Moo Lath pigs with average live weight of 12.3 ± 0.7 kg were housed in individual pens and assigned to four treatments replicated four times, according to a completely randomized design. The treatments were: soybean meal (SBM), rice distillers’ byproduct (RDB), brewers’ grains (BG) and ensiled taro foliage (ETF).They were fed a basal diet of ensiled cassava root (ECR) and different sources of protein: soybean meal (SBM) as control diet, rice distillers’ by products (RDB), brewers’ grains (BG) and ensiled taro foliage (ETF).

Feed resources

Cassava roots were purchased from farmers. They were cleaned and chopped prior to conservation as silage. Rice distillers’ by product was collected from the stallholders’ wine distilleries, located in Xaythany district, Vientiane capital. Brewers’ grain was available in the factory of “Lao beer”. The taro foliage (leaves and petioles) were harvested from waste water lagoons in the outskirts of Vientiane city. They were chopped, wilted under shade for 12 hours and ensiled in plastic sacks. The rice distillers’ by-product and brewers’ grains were also stored in plastic sacks prior to being fed to the pigs.

Feeding and management

The pigs were vaccinated against hog cholera, de-wormed with Ivermectin (1 ml/20 kg LW) and adapted to the new feeds for 12 days prior to collection of data. The daily allowances were prepared immediately prior to feeding at 7:30 am and 4:30 pm, water was freely accessed through nipple drinkers in each pen.

Data collection and proximate analysis

Feeds offered and refused were recorded daily and samples retained at -18°C until the end of the experiment when they were bulked on an individual animal basis for determination of DM, crude protein, crude fiber and ash according to AOAC (1990) procedures. The pigs were weighed every 14 days during the experiment. Average daily weight gain was determined by linear regression of weight (Y=kg) on time (X=days).

Statistical analysis

The data (feed intake, live weight change and feed conversion) were analyzed by the GLM option in the ANOVA program of the Minitab software (Minitab 2016). Sources of variation in the model were sources of protein, replicates and error.

Results

Chemical composition of basal diets (% DM basis)

Levels of protein were similar in the rice distillers’ byproduct and brewers’ grain, but much lower in the ensiled taro foliage. The crude fiber was higher in the brewers’ grain and ensiled taro foliage than in soybean meal with RDB having the lowest fiber level (Table 1).

Feed intake, weight gain and feed conversion

The intake of dry matter was higher in diets having the protein supplied by soybean meal or RDB (Table 3; Figure 1)). This was reflected in better growth (Figure 2) and feed conversion (Figure 3) in pigs fed RDB or soybean meal as the protein supplement. Poorest performance was when ensiled taro foliage was the protein source.

Figure 1. Dry matter intake of Moo Lath pigs fed different sources of protein	Figure 2. Live weight gain of Moo Lath pigs fed different sources of protein
Figure 3. Feed conversion of Moo Lath pigs fed different sources of protein

Discussion

Brewers’ grains (BG) and RDB supported similar increases in growth rate in Moo Lath pigs when fed at low levels of 4% of the diet (Sivilai et al 2017, 2018). However, when fed as the main source of protein, as in the present experiment, the RDB was plainly superior and led to improved growth performance. Due to RDB “Hem” mentioned in a high value of crude protein and abundant in amino acid (Manh et al 2009). At low levels it is hypothesized that both brewers’ grain and RDB function as sources of “prebiotic” (Sivilai et al 2019), derived from the beta glucan known to be present in the cell wall of barley (the case of brewers’ grains) and of yeast (the case of RDB). Identifying the respective roles of brewers’ grain and of RDB as prebiotics in the present experiment is not possible as it would have required the measurement of typical responses to prebiotics such as lowered pH in the cecum and the presence in this organ of short chain volatile fatty acids, acetic and butyric acids products of the fermentation of beta-glucan and related cell carbohydrates that are not digested by intestinal enzymes (García-Curbelo 2020).

RDB differs from brewers’ grain in that it is made exclusively from polished rice, containing only 2.8% protein in DM ( Feedipedia.org) thus the greater part of the protein in RDB must be derived from the yeast used in the fermentation. In contrast, brewers’ grain is usually made from barley having 11.3% protein (feedipedia.org). The conclusion from this comparison is that the balance of essential amino acids will be better in RDB than in brewers’ grain. The other characteristic of both RDB and brewers’ grains is that both appear to act as ”prebiotics” (Sivilai et al 2017). However, for this effect to be manifested the concentrations needed of both additives are only 4% of the diet (Sivilai et al 2018). It is not known if the “prebiotic” benefits from these supplements are still manifested when these feeds are included at the much higher levels (>50%) as in the present experiment.

On the basis of present knowledge, it would appear that the benefits of RDB over brewers’ grain in diets of growing pigs, are mainly due to the superior protein quality, coupled with the lower level of crude fiber in the RDB.

Conclusion

• The dry matter intake was higher, which was reflected in better growth and also improved feed conversion in pigs fed protein supplied by SBM or RDB.
  
  
• Performance was poorest when ensiled taro foliage was the protein source.
  
  
• RDB can replace soybean meal in diets of growing Moo Lath pigs with no loss in performance

Acknowledgement

The authors acknowledge support for this research from the Faculty of Agriculture (FAG), National University of Laos (NUoL) for co-research funds. Special thanks are given to Animal Science Students for their practical help, field work and laboratory assistance during experiment.

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