Utilization of by-product from Soya bean for growing pigs

Tran Thi Thu Hong, Vo Thi Kim Thanh, Dao Thi Phuong,
Phung Thi Luu and E R Ørskov*

 Hue College of Agriculture and Forestry,
* International Feed Resource Unit, Macaulay Land Use Research Institute, Scotland, UK

 
Abstract

An experiment was carried out to determine the chemical and nutritive value of Soya bean residue (SBR), and effects on performance of growing crossbred (Large White × Mong Cai) pigs. The replacement levels were 0, 33, 66 and 99% of the fish meal. The experimental design was a 4*4 Latin square with periods of 10 days, 5 for adaptation and 5 for collection of faeces and urine.

The apparent digestibility coefficients for DM, OM and crude protein decreased slightly as the level of SBR in the diets increased with a significant reduction from the 66 to 99% fish meal replacement level. N retention showed a different trend with increases up to the 66% fish meal replacement, followed by lower values at the 99% replacement level, which did not differ from the N retention  observed on the control and 33% fish meal replacement level.

In an on-farm trial with 24 fattening pigs,  performance with 66% replacement of the fish meal by the Soya bean by-product was similar to that on the control diet, but with  superior economic returns.

Key words: Pigs, Soya bean residue, fish meal, crude protein, digestibility, growth, conversion
 

Introduction

The people in peri-urban Hue City commonly keep pigs, using cassava root meal and by-product and low value rice.These feed sources have a low content of protein. Potential protein supplements in the area are groundnut cake and fish meal, but these are all relatively expensive. There are many by-products and food-processing residues that are cheaper and not used and they cause pollution to the city environment. Soya bean residue is a by-product from the processing of soya beans. It has a crude protein content of 19% C and is thus a potentially cheap protein source for growing pigs.

The present study was carried out to determine the chemical composition and nutrient value of Soya bean by-product for growing pigs, by measuring digestibility coefficients and N retention with graded levels of the by-product replacing fish meal. The optimum level according to the results of this test were evaluated in an on-farm comparison with the traditional diet.

Materials and methods

Location

The research was carried out at the Hue University of Agriculture and Forestry, Hue City and in an on-farm experiment in Vy Da hamlet, which is situated in the East of Hue City. The region has a range of  mean maximum and minimum air temperatures of 29.8 ºC and 18.6ºC with relative humidity in the range of 94 and 72%, respectively.

 On-station research

Animals

Four crossbred (Large White x Mong Cai) castrated male pigs from the same litter, with an average live weight of 40 kg at the beginning of the study were used. The pigs were housed individually in metabolic pens that allowed separation of urine and faeces. All animals were de-wormed and vaccinated before conducting the experiment. The daily feed intake was restricted to 4% (DM basis) of mean body weight and all animals were fed daily at 9:00 and 16:00 h. Water was available from automatic drinkers. 

Experimental design and treatments

The basal diet was cassava root meal and fish meal to provide 12.6% crude protein (DM basis). The treatments were four levels of soya bean by-product (SBR) replacing 0, 33, 66 or 99% of the fish meal protein (Table 1). The SBR was boiled before feeding to the pigs to reduce the levels of anti-nutritional factors contained in the raw bean (Table 2).

 

 

Table 2. Composition of diet ingredients
Parameters	Raw SBR	Boiled SBR	Fish meal	Cassava meal
Air-dry basis, %
Dry matter	16.4	8.5	81.5	86.4
DM basis, %
Crude protein	19.1	19.3	55.7	2.9
Crude fiber	15.3	15.2	-	1.7
Total ash	6.2	6.2	23	0.8

 

The design was a 4*4 Latin square arrangement with 4 pigs, 4 diets and 4 periods, which consisted of  5 days for adaptation and 5 days for collection of urine and faeces. Faeces were collected and sampled twice a day and the samples kept in a freezer at +4^oC until analysed. Prior to analysis, faeces were homogenized, sub-sampled and dried at 60ºC and ground to pass a 1 mm screen. The urine was preserved by adding 100 ml of 10% H₂SO₄ to the collection jar and stored at -20ºC.  Feeds offered and refused and faeces were analysed for dry matter, crude protein, crude fiber and total ash. Urine was analyzed for crude protein.  

Chemical analysis

DM was determined by oven drying at 105ºC over-night. Crude protein, ash and fibre were analysed  according to AOAC (1984).

Statistical analysis

The descriptive statistics of Minitab (Version 12) were used to compare the chemical composition data.  Digestibility and N balance measurements were analysed using the General Linear Model, the sources of variation being treatments, animals, periods and error.

On farm research

Twenty four pigs were divided in two groups, which were fed the traditional diet and the experimental diet based on the 66% fish meal replacement rate, that was found to be optimal in the on-station trial. The diet composition (Table 3) was calculated from literature values (NIAH 1995; McDonald et al 1998). The pigs were weighed every month and the total feed consumed was recorded.

 

Table 3. Dietary ingredients and calculated amounts of crude protein, dry matter (DM) and energy (ME) intakes during the growing (25-50 kg) and the finishing (50-70 kg) period.
	25-50 Trad.	25-50 Exp.	50-70 Trad.	50-70 Exp.
Ingredients, %DM
Rice	66.7	40.4	66.7	48.8
Fish meal	23.2	10.4	18.1	3.6
SBR	-	49.2	-	47.6
Sweet potato vine	10.1	-	15.2	-
Total	100	100	100	100
Chemical comp.
CP, %	20.5	19	18.4	15.7
ME, MJ/Kg	15.6	13	14.9	13.1

 

 

Results and discussion

On-Station research

There were no differences in the composition of SBR after boiling compared with the raw form (Table 2), but the boiled product had a more attractive smell for the pigs and boiling would have decreased the concentration of  anti-nutritional factors contained in the raw bean (Sarria and Preston 1992). The CP and CF contents of the SBR were lower than reported by NIAH (1995) (27.9 and 17.3% in DM, respectively), but total ash was slightly higher (6.2 compared to 4.3% in DM).

 

Total tract dry matter, organic matter and crude protein digestibility decreased with increasing level of SBR, with the major difference between the 6 and 99% replacement level (Table 4 and Figure 1). Crude protein digestibility was depressed more severely than the other nutrients. The decrease in digestibility was probably due to the increasing fibre content of the diet (from 1.4% in the control diet to 9.7% in the SBR₉₉ diet).  (9.7% compared with 1.4 and 4.2 % respectively). These results are similar to those reported in earlier studies with fibre-rich forages carried out in Vietnam (Du Thanh Hang et al 2000; Bui Huy Nhu Phuc 2000). 

 

Table 4.  Mean values for apparent digestibility indices (%)
	Level of replacement of fish meal protein by SBR
	0	33	66	99	SEM	Prob.
Dry matter	93.5c	91.0abc	91.0abc	87.8a	0.9	0.010
Organic matter	95.0cd	93.2bc	91.8b	87.7a	0.8	0.001
Crude protein	89.1c	83.4b	79.6b	71.7a	1.8	0.001
abcd Means in the same row without letter in common differ at P<0.05

 

 

Figure 1. Effect of level of inclusion of soybean residues (SBR) on nutrient digestibility, %

 

Table 5. Effect of levels of replacement of protein from SBR on N retention
	Level of replacement of protein from SBR(%)
	0	33	66	99	SEM	Prob.
N balance, g/day
Intake	15.4	15.5	15.7	15.9
Faeces	1.7a	2.6b	3.2b	4.5c	0.3	0.001
Urine	7.7b	6.4b	4.5a	4.5a	0.5	0.002
Retention	6.0	6.6	8.0	6.9	0.6	0.120
Retention % of digested	43.7a	50.8a	64.3b	60.2b	3.9	0.013
Retention % of intake	39.0	42.5	51.1	43.2	3.6	0.160

 

 

Total N retained tended to be highest on the SBR₆₆ diet and was significantly higher when expressed as percentage of N digested (Table 5). This appeared to be  due to lower urinary N losses on the SBR₆₆ diet compared to the SBR₀ and SBR₃₃ diets. In turn the  lower urinary N losses on the SBR₆₆ diet could have  been due to the superior amino acid balance in this diet as a result of optimum relative proportions of SBR and fish meal.  

Growth trial on-farm

The growth performance of the pigs was not affected by replacing the fishmeal and sweet potato vines with SBR (Table 6). However, the economic benefits were much higher when the fish meal was replaced with the soybean residue due it's much lower cost.

 

Table 6. Effect of replacing fishmeal with SBR on growth performance of fattening pigs (90 day trial; 12 pigs per treatment)
	Traditional	Experiment	SEM/Prob.
Initial LW (kg)	25.8	26.3	0.9/0.738
Final LW (kg)	68.7	70.5	2.2/0.559
Daily gain (g/day)	476	492	16.2/0.502
Feed cost/ kg gain (VND)	6.159	4.190

 

Conclusions

• The replacement of 66% of the fish meal in traditional diets by soybean residues reduced only slightly the nutrient digestibilities, but resulted in improved N retention as a percentage of the N digested.

• Compared to a traditional diet, replacing  sweet potato vines and 66% of the fish meal by soybean residue resulted in similar growth performance and far superior economic returns.

• It can be recommended that pig producers utilize high levels of soybean residue that would otherwise be wasted.

 

Acknowledgements

This research was partially financed by the bilateral SAREC project 2000-2002.

References