Evaluation of Chinese Brown Rice as an Alternative Energy Source in Pig Diets

A total of six crossbred barrows (Duroc×Landrace×Large White, 44.17±1.94 kg BW) were housed conducted to evaluate apparent fecal digestibilities of Brown Rice (BR) as an alternative energy source in growing pigs. Pigs were housed individually on metabolism crate on the basis of body weight. Four treatments contained: 1) 100% of corn-soybean meal (C100; Control diet), 2) 75% of corn-soybean meal diet plus 25% of corn meal (C25), 3) 100% of brown rice-soybean meal diet (BR100), 4) 75% of brown rice-soybean meal diet plus 25% of brown rice meal (BR25). Brown rice has an excellent gross energy and crude protein composition compared to corn. The BR used had 3,801 kcal of gross energy/kg, 8.0% crude protein, 2.6% of ether extract, 0.035% calcium and 0.35% total phosphorus. The best digestibilities of energy (87.75%), DM (81.71%) and CP (78.57%) were observed in BR 100 group and the worst were found in Corn 25 group. The nutrient digestibility was not significantly different in most nutrients. Through this experiment, BR appeared a good alternative energy source that can replace corn yellow to 100% in growing pigs. Therefore, the price relationship between corn and BR may provide an excellent opportunity for pork producers to use BR in order to reduce feed costs provided that diet has been balanced for digestible amino acids. (Asian-Aust. J. Anim. Sci. 2002. Vol 15, No. 1 : 8993)


INTRODUCTION
An important challenge is to reduce the production cost in animal industry.Feed is the primary factor to increase the production costs in animal production, especially for the monogastric animals.Corn grain is most commonly used carbohydrate or energy source in pig diets because of its availability and good quality.However, high price of corn sometimes limited its utilization in feed industry.
Thus there is a great need to replace corn with alternative carbohydrate sources in the animal diets.Recently, Centre-China Agricultural University found that brown rice (BR), as a nonconventional energy source, which was originated from China, has a relatively high carbohydrate and protein contents.Its protein content is comparable with those of corn grain.
China is the world's largest producer of BR with an annual production of 2.4 million tons (80% of the total rice products.BR's price is relatively low (2/3 of corn), and energy content is high (table 3).But BR also contains approximately 25% straight chain starch and these compounds have been suggested to impart a poorer use in human foods (He et al., 1994).
Precise statements on their nutritional values are limited.It is essential to determine the nutritional values of BR for the use of animal feeds.
Therefore, this experiment was designed to evaluate BR as an alternative energy source in growing pig diets.In this experiment, the availability of proximate nutrients and gross energy were measured.
All digestibility trial, chemical analysis and statistical analysis were conducted in the Ministry of Agricultural Feed Industry Center, College of Agricultural Animal Science and Technology, China Agricultural University in Beijing, China.individual metabolic crates.The barrows were fed at 08:00 h and 20:00 h each day.Fecal samples were collected on day 4, 5, 6 and 7 after 3 days of adaptation period.To measure the nutrient digestibility of the experimental diets, the digestibility coefficient was calculated by total fecal collection method.Experimental diets and water were fed to satiation.Collected excreta were pooled and dried in an airforced drying oven at 60°C for 72 h to gain constant dry weight and were ground with 1 mm mesh Wiley mill for chemical analysis.
Chemical analysis : Analysis of proximate nutrients composition of experimental diets and excreta was conducted according to the methods of AOAC (1990), and amino acids composition was measured using an automatic amino acid analyzer (Pharmacia Biotech, Biochrom 20, England) after 24 h of acid hydrolysis in 6 N HCl.Phosphorus content were measured using the UV-visible spectrophotometer (Hitachi, U-1000, Japan) and gross energy content of feeds and excreta were measured using the Bomb Calorimeter (Parr Instrument Co., Model 1241, USA).Chromium was measured using atomic absorption spectrophotometer (Shimadzu, AA6145F, Japan).The fatty acid compositions of the experimental diets were measured using gas chromatography (HP 5890, Hewlett-Packard Co., USA) according to the method of Lepage and Roy (1986).Blood samples were collected from three pigs of each treatment.The blood samples were centrifuged (3,000/rpm) at 5°C for 15 minuets.The serum was stored at -20°C until the analyses for blood urea nitrogen and total glucose analyzed using commercially available kits.

Statistical analysis
Statistical analysis for the present data was carried out by comparing means according to Duncan's multiple range  test (Duncan, 1955), using General Linear Model (GLM) procedure of SAS (1985) package program.

Chemical composition
Chemical compositions of corn and brown rice used in this experiment were given in table 3.
Brown rice has an excellent gross energy and crude protein composition compared to corn.The BR used had 3,801 kcal of gross energy/kg, 8.0% crude protein, 2.6% of ether extract, 0.035% calcium and 0.35% total phosphorus.But the corn (2.2%) was almost three times higher in crude fiber than brown rice (0.7%).These data are similar to the results by He et al. (1993).In terms of chemical composition at seems that BR has high potential to be a good feed ingredient for animals.BR also has an excellent fatty acids composition.Out of the energy sources predominantly composed of long-chain fatty acids with chain lengths of 14 or more carbons, corn was relatively high in proportion of unsaturated fatty acids (USFA>40.95%),while the BR was relatively high in proportion of saturated fatty acids (SFA>68.91%).Also, corn was almost one and half times higher in USFA/SFA ratio (0.6936) than BR (0.4512).Usually, feeds containing high levels of USFA produce pork with low oxidative stability (He et al., 1995).The USFA and SFA concentrations of the brown rice meal is better than that of corn meal (He et al., 1995).He et al. (1994) reported that gross energy (GE) and crude protein concentrations of brown rice were 4,003 kcal/kg and 8.8% and corn were 4,006 kcal/kg and 8.6%, respectively.The apparent digestibilities of BR for pigs and poultry have been determined by the fecal methods (He et al., 1994).

Nutrient digestibility
Nutrient digestibility from the present experiment was summarized in table 4 and figure 1.During the overall period, all BR groups showed better digestibility than corn diet group in energy, DM and CP.BR 100 diet showed the best gross energy digestibilities, which was significant higher (p<0.05)than those of pigs fed corn diets.The best digestibilities of energy (87.75%),DM (81.71%) and CP (78.57%) were observed in BR 100 group and the worst were found in Corn 25 group.The nutrient digestibility was not significantly different in most nutrients.Nutrient digestibility had a tendency (not significant) to decrease as the level of corn in the diet was increased.As noted by He et al. (1994), apparent nitrogen digestibility in pigs fed BR (78.71%) in the diet was significantly higher than corn groups (69.17%, p<0.05).The present study suggested similar trends with that result of He et al. (1994).He et al. (1994) reported that apparent crude protein  digestiility and metabolizable rate were 73.71% and 65.03% in brown rice and 69.17%, 59.89% in corn, respectively.
The overall results suggest that BR meal can be replacing 100% corn in diet fed to growing pigs.However, poultry fed BR meal responses to achromia in skin or in eggs and therefore it was suggested to add vitamin A, yellow pigments, alfalfa or pine needle meal when BR was included in the diet (He et al., 1999).

Nutrients excretion
Table 5, figure 3 and figure 4 summarized the effect of different energy sources on the nutrient excretion.It showed that nutrient excretion was obviously affected by energy sources.Dry matter and nitrogen excretion had a tendency to decrease when the level of BR was increased, but no significant difference was found (p>0.05).

Plasma concentrations
The plasma concentration of urea nitrogen and total glucose of pigs were presented in table 6 and figure 3. Blood urea nitrogen (BUN) concentration ranged from 16.5 to 23 mmol/dL in this experiment.There was statistical significance found in BUN concentration among individual treatments and tended to decrease in pigs fed corn 25% and BR 25% diets.Eggum (1970) found an inverse relationship between plasma urea nitrogen and dietary amino acid balance.This relationship has been used to determine amino acid requirements in pigs (Brown and Cline, 1974).In this experiment, BUN concentration was highest in Corn 100 diet but lowest in Corn 25 diet (p<0.001).Total glucose (TG) level was examined and significant difference was detected among treatments (p<0.05).All BR groups showed better BUN and TG than the corn groups.

IMPLICATIONS
BR is a relatively unknown carbohydrate source, which has good amino acids and nutrient composition.Through  .Blood urea nitrogen and total glucose of pigs this experiment, BR appeared a good alternative energy source that can replace corn yellow to 100% in growing pigs.Therefore, the price relationship between corn and BR may provide an excellent opportunity for pork producers to use BR in order to reduce feed costs.However, the reason of the improvement in growth performance and amino acids digestibility was not conducted to determined in this study.Thus more study is required to show the mechanism in which how BR improve the performance of monogastric animals including broilers and hens.
Figure 1.The apparent fecal nutrient digestibility of growing pigs (%)

Table 1 .
Experimental design

Table 3 .
Nutrient composition of corn and brown rice* * Analyzed value.

Table 4 .
Effects of brown rice on apparent fecal nutrient digestibility of growing pigs (%) Values with different superscripts within the same column significantly differ (p<0.05).

Table 5 .
Nutrients excretion of growing pigs (g nutrient excretion/1,000 g feed intake)

Table 6 .
Plasma concentrations of urea nitrogen and total glucose of pigs fed experimental diets