Comparison of Nutritional Value of Tomato Pomace and Brewer’s Grain for Ruminants Using in vitro Gas Production Technique
The aim of present study was to determine the chemical composition and estimate the nutritive value of tomato pomace and brewers’ grain using in vitro gas production technique in sheep. Tomato pomace samples were collected from 4 tomato processing factories in East Azerbaijan, Iran and brewers’ grain samples were obtained from Behnoush Food Industrial Company, Karaj, Iran. Feed samples (200 mg from each ) were incubated with rumen liquor taken from 3 fistulated rams at 2, 4, 6, 8, 12, 16, 24, 36 and 48 h. The results showed that the Organic Matter (OM), Neutral Detergent Fiber (NDF) and Non Fibrous Carbohydrates (NFC) in brewers’ grain were significantly higher than that of tomato pomace (p<0.05), while Crude Protein (CP), Ether Extract (EE) and Acid Detergent Fiber (ADF) in tomato pomace were significantly greater than that of brewers’ grain (p<0.05). There were significant differences in Organic Matter Digestibility (OMD), Short Chain Fatty Acids (SCFA) and Metabolizable Energy (ME) contents between the two food industrial by-products (p<0.05). Gas productions at 24 h for tomato pomace and brewers grain were 38.99 and 31.14 mL, respectively. In an overall conclusion it seems that, the nutritive value of tomato pomace was higher than that of brewers’ grain for ruminants.
to cite this article:
A. Aghajanzadeh-Golshani, N. Maheri-Sis, A. Mirzaei-Aghsaghali and A. Baradaran-Hasanzadeh, 2010. Comparison of Nutritional Value of Tomato Pomace and Brewer’s Grain for Ruminants Using in vitro Gas Production Technique. Asian Journal of Animal and Veterinary Advances, 5: 43-51.
Developing food industrial factories consequently produced large amount of
wastes and by-products. Dumping or burning wastes or agro-industrial by-products
causes potential air and water pollution problems. High-moisture wastes are
also difficult to burn. Many by-products have a substantial potential value
as animal feedstuffs. Ruminants, especially, have the unique capacity to utilize
fiber, because of their rumen microbes. This means that cereals can be largely
replaced by these by-products. Consequently the competition between human and
animal nutrition can be decreased. Nevertheless, there is an increased cereal
supply owing to genetic and management improvement. The utilization of agro-industrial
by-products may be economically worthwhile, since conventional feedstuffs are
often expensive. However, livestock have historically utilized large amounts
of well-known and widely-available traditional by-products such as oil meals,
bran, middling, brewers grains, distillers grains, beet pulp and molasses (Boucque
and Fiems, 1988 ). But less conventional by-products have become available,
such as vegetable-and fruit- processing residues. The extent of by-products
utilization as a feed ingredient depends on the costs of the conventional feedstuffs,
the safety for animal health and the attractiveness of alternative uses. As
some raw materials can be used for different production processes, the available
amount to the various by-products is difficult to estimate and it is even more
difficult to assess the quantity used as animal feed (Boucque
and Fiems, 1988). Therefore, the nutritional value of regional by-products
should be the evaluated, as feed value of feedstuffs may differ greatly from
one location to another.
Tomato (Lycopersicon esculentum Mill.) is one of the most widely cultivated
vegetable crops in Mediterranean Countries. Significant amounts are consumed
in the form of processed products such as tomato juice, paste, puree, ketchup
and sauce. During tomato processing a by-product, known as tomato pomace, is
generated. This by-product represents, at most, 4% of the fruit weight (Del
Valle et al., 2006). Dried tomato pomace contains 22.6-24.1% protein,
14.5-15.7% fat and 20.8-30.5% fiber. This by- product is a good source of vitamin
B1 and a reasonable source of vitamins A and B2 (El-Boushy
and Vander-Poel, 1994). Bordowski and Geisman (1980)
reported that tomato pomace seeds protein contains approximately 13% more lysine
than soy protein. In Iran, production of tomato pomace exceeds 150,000 tons
year-1 (Besharati et al., 2008). The
potential use of these wastes in ruminant ration should participate in reducing
the shortage of feedstuffs and subsequently increase milk and meat production
in Iran. However, little is known about their fermentation pattern in the rumen
and a better understanding of their digestion and products of fermentation is
necessary in order to properly balance their introduction into the diets and
the knowledge about their potential feeding value is insufficient (Besharati
et al., 2008).
Brewers grains are the most important by-product of brewery industry.
Every 100 L of beer accounts for an average 20 kg of brewers grains (Mussatto
et al., 2006). Brewers grains are often used as a livestock
feed. Because they provide protein, fiber and energy, are used in a variety
of diets. Protein in Brewers grains can meet a significant portion of
supplemental protein requirements; in addition, they provide fiber and needed
bulk in the diets of ruminants. On DM basis, it contains a range of 220 to 280
g kg-1 CP and 2.5 Mcal ME kg-1 DM (NRC,
2001). Brew residues can be in the form of either dried brewers grains
or wet brewers grains, which can be marketed directly. Moisture content
in wet brewers grains ranges between 650-800 g kg-1 (Aguilera-Soto
et al., 2007). The dried brewers grains are easy to store
because of its low moisture content. Brewers grains are suitable as forage
source especially at the farms located near breweries (Younker
et al., 1998; Aguilera-Soto et al., 2007).
Several methods such as in vivo, in situ and in vitro
techniques have been used in order to evaluate the nutritive value of feedstuffs
(Maheri-Sis et al., 2008). The in vitro
gas production technique has proved to be a potentially useful technique for
feed evaluation (Menke and Steingass, 1988 ; Getachew
et al., 2004) as it is capable of measuring rate and extent of nutrient
degradation. In addition, in vitro gas production technique is less expensive,
easily to determine (Getachew et al., 2004) and
suitable for use in developing countries (Chumpawadee et
al., 2005; Maheri-Sis et al., 2007 ,
2008). This method also predicts feed intake, digestibility,
microbial nitrogen supply and amount of short chain fatty acids, carbon dioxides
and metabolizable energy of ruminants feed (Babayemi, 2007;
Maheri-Sis et al., 2008). When planning diet
formulation, cost, chemical composition and digestibility of the energy of the
feed source should be fully taken into account. Numerous varieties of energy
feeds are available in tropical zones. However, there is insufficient information
available regarding the effect of feed used on kinetics of gas production (Chumpawadee
et al., 2007).
The aim of this study was to determine chemical composition and estimate the
nutritive value of tomato pomace and brewers grain using in vitro
gas production technique.
MATERIALS AND METHODS
Animals and Feeds
Three fistulated Gezel rams were used for rumen liquor collection for application
in gas production technique. The experimental samples were Tomato Pomace (TP)
and Brewers Grain (BG). The TP samples were collected from four tomato
processing factories in East Azerbaijan, Iran and BG samples were obtained from
Behnoush Food Industrial Company, Karaj, Iran. The collected samples were dried,
mixed and milled through a 1 mm sieve in Animal Nutrition Laboratory of Tabriz
University, Tabriz, Iran.
Collected samples were milled through a 1 mm sieve for chemical analysis
and in vitro gas production procedure. Dry Matter (DM) was determined
by drying the samples at 105°C overnight and ash by igniting the samples
in muffle furnace at 525°C for 8 h. Nitrogen (N) content was measured by
the Kjeldahl method. Crude Protein (CP) was calculated as N*6.25 (AOAC,
1990). Neutral Detergent Fiber (NDF) was determined by procedures outlined
by Van Soest et al. (1991); sulfite was omitted
from NDF analysis. All of chemical analyses were performed in the Laboratory
of Animal Nutrition, Islamic Azad University, Shabestar Branch, Shabestar, Iran
(Mar. 2008 to Aug., 2008).
In vitro Gas Production
Rumen fluid was obtained from three fistulated Gezel rams fed twice daily
at the maintenance level with a diet containing alfalfa hay (60%) and concentrate
(40%). The samples were incubated in vitro with rumen fluid in calibrated
glass syringes following the procedures of Menke et al.
(1979). Two hundred miligram samples were weighed in triplicate into calibrated
glass syringes of 100 mL. The syringes were prewarmed at 39°C before the
injection of 30 mL rumen fluid-buffer mixture into each syringe followed by
incubation in a water bath at 39°C. Readings of gas production were recorded
before incubation 0 and 2, 4, 6, 8, 12, 16, 24, 36 and 48 h after incubation.
Total gas values were corrected for blank incubation. Cumulative gas production
data were fitted to the model of Orskov (1979):
Y = a + b (1-e-ct)
||The gas production from the immediately soluble fraction (mL)
||The gas production from the insoluble fraction (mL)
||The gas production rate constant for the insoluble fraction (b)
|a + b
||Potential gas production (mL)
||Incubation time (h)
|| Neperian value (2.718282)
|| Gas produced at time (t)
The Non Fibrous Carbohydrates (NFC), Short Chain Fatty Acids (SCFA), Digestible
Organic Matter (DOM) and Metabilizable Energy (ME) values in experimental by-products
were calculated using equations as below:
NFC =100-(NDF +CP +EE +Ash) (NRC, 2001)
SCFA = 0.0222 Gas 0.00425 (Makkar, 2005)
DOM = 0.9991 Gas + 0. 595 CP + 0.181 CA + 9 (Menke and Steingass,
ME = 0.157 Gas + 0.084 CP + 0.22 EE 0.081 CA + 1.06 (Menke
and Steingass, 1988 )
where, Gas is gas production at 24 h incubation (mL 200 mg-1 DM);
a, b, c are gas production parameters described by Orskov
(1979) and NDF, CP, EE, CA are neutral detergent fiber, crude protein, ether
extract, crude ash (% DM) , respectively. Gas production test was carried out
in the Laboratory of Animal Nutrition, Tabriz University, Tabriz, Iran (Aug,
All of the data were analyzed by using software of SPSS
(2002) and means of two sample groups were separated by independent-samples
t-test (Steel and Torrie, 1980).
RESULTS AND DISCUSSION
The Organic Matter (OM), Neutral Detergent Fiber (NDF) and non Fibrous Carbohydrates
(NFC) in brewers grain were significantly higher than that of tomato pomace
(p<0.05) (Table 1) while Crude Protein (CP), Ether Extract
(EE) and Acid Detergent Fiber (ADF) in tomato pomace were significantly greater
than that of brewers grain (p<0.05). The NDF content of brewers
grain was lower than that obtained by Pereira et al.
(1998) but higher than that obtained by Madrid et
al. (2002), in line with the findings of DePeters
et al. (1997), Batajoo and Shaver (1998)
and Afrozieh and Pirmohammadi (2007). The ADF content
of brewers grain was higher than the findings of DePeters
et al. (1997), Pereira et al. (1998)
and Madrid et al. (2002) and in line with Afrozieh
and Pirmohammadi (2007). The OM content of brewers grain was in agreement
with several researches findings (Alawa et al., 1988;
DePeters et al., 1997; Batajoo
and Shaver, 1998; Pereira et al., 1998).
The CP content of brewers grain were lower than those reported by DePeters
et al. (1997), Batajoo and Shaver (1998),
Pereira et al. (1998), Madrid
et al. (2002) and Afrozieh and Pirmohammadi (2007)
and in line with Alawa et al. (1988) and Mussatto
et al. (2006). The NDF content of tomato pomace was lower than Weiss
et al. (1997), Denek and Can (2006), Besharati
et al., 2008 and Taghizadeh et al. (2008)
and in line with Chumpawadee et al. (2007) and
Chumpawadee and Pimpa (2008). The ADF content of tomato
pomace was lower than those of Weiss et al. (1997),
Denek and Can (2006), Chumpawadee
et al. (2007), Besharati et al., 2008,
Chumpawadee and Pimpa (2008) and Taghizadeh et al.
(2008). The OM content of tomato pomace was lower than those Weiss
et al. (1997), Ayhan and Aktan (2004), Del
Valle et al. (2006) and Denek and Can (2006)
but higher than those Besharati et al. (2008)
and Chumpawadee and Pimpa (2008) and in agreement with
several researches (Boucque and Fiems, 1988; Chumpawadee
et al., 2007).
||Chemical composition of tomato pomace and brewers grain on
dry matter basis (%)
|NS: Non significant; *p<0.05, Data presented as Mean±SD
The CP content of tomato pomace was lower than those reported by Boucque
and Fiems (1988) and Chumpawadee et al. (2007)
but higher than those National Academy of Science (1983),
Weiss et al. (1997), Ayhan
and Aktan (2004), Del Valle et al. (2006),
Denek and Can (2006) and Chumpawadee
and Pimpa (2008) and in line with Besharati et al.,
2008 and Taghizadeh et al. (2008).
The wide range of variation in chemical composition of experimental by-products
between several researches can be due to different original materials, growing
conditions (geographic, seasonal variations, climatic conditions and soil characteristics),
extent of foreign materials, impurities and different processing and measuring
methods (Maheri-Sis et al., 2008). Different
chemical composition leads to different nutritive value, because chemical composition
is one of the most important indices of nutritive value of feeds. Variation
in chemical components of feeds such as starch, NFC, OM, CP, NDF, ADF and soluble
sugars contents can be resulted in variation of in vitro gas production
extent (Getachew et al., 2004; Maheri-Sis
et al., 2008).
Gas production volumes (mL 200 mg-1 DM) in different incubation
times are presented in Table 2 gas production parameters (a,
b, c) and calculated amounts of SCFA, OMD and ME of tomato pomace and brewers
grain are shown in Table 3.
The gas volumes for tomato pomace in different incubation times (except of
2 h incubation) were significantly higher than that of brewers grain (p<0.05).
Gas volume at 24 h incubation (for 200 mg dry samples), soluble fraction (a),
insoluble but fermentable fraction (b), for tomato pomace was 38.99, -5.22 and
50.25 and for brewers grain were 31.14, 0.043 and 42.69 mL, respectively
(Table 2 and 3). The negative (a) value
for tomato pomace due to delay in onset of fermentation and microbial attachment
was in agreement with Chumpawadee et al. (2007).
Rate of gas production expressed in mL h-1 (c) in tomato pomace (0.1143)
was significantly (p<0.05) greater than brewers grain (0.0614). The
gas volume after 24 h incubation in current study for tomato pomace was higher
than what was reported by Chumpawadee et al. (2007)
(38.99 vs. 24.60 mL) and almost in line with Besharati et
al. (2008) findings (38.99 vs. 34.48 mL).
||Comulative gas production volume (mL 200 mg-1 DM)
at different incubation times for experimental by-products
|NS: Non significant; *p<0.05, Data presented as Mean±SD
||The gas production parameters, organic matter digestibility
(OMD), short chain fatty acids (SCFA) and metabolizable energy (ME) contents
of experimental by- products
|a: The gas production from the immediately soluble fraction
(mL), b: The gas production from the insoluble fraction (mL) c: The gas
production rate constant for the insoluble fraction, (b) NS: Non significant,
*p<0.05. Data presented as Mean±SD
The gas volume after 24 h incubation for brewers grain was lower than
Getachew et al. (2002) findings. They are reported
that gas production volume at 24 h incubation time for brewers grain was
different between laboratories (35.3-41.5 mL). Different gas production in these
studies can be due to different chemical constituents of by-products, animal
types and breeds and quality of inoculums source (Menke
et al., 1979; Getachew et al., 2004).
There was a positive correlation between NFC content of feeds and gas production,
but feed CP, NH3-N and NDF levels were negatively correlated with gas production
(Getachew et al., 2004; Maheri-Sis
et al., 2008). As presented in our data, the volume of gas production
had a negative correlation with NDF levels of experimental by products. Different
gas volume and estimated values (ME, SCFA and OMD) could be due to different
EE content of by products. Therefore, tomato pomace with low NDF and high EE,
should have greater gas volume, ME, SCFA and OMD than brewers grain.
The ME, SCFA and OMD of tomato pomace were significantly higher than that of
brewers grain (p<0.05). The ME content of tomato pomace and brewers
grain in this experiment were 11.77 and 9.05 MJ kg-1 DM, respectively.
The ME value of tomato pomace was greater than those reported by Chedly
and Lee (1999), Chumpawadee et al. (2007)
and Besharati et al. (2008). The ME content of
brewers grain was higher than that reported by Chedly
and Lee (1999), while lower than those findings of Alawa
et al. (1988), Board (2002) and Getachew
et al. (2002) . Difference of energetic value of feedstuffs between
several researchers may be due to different chemical content and measuring method
and also variation inter and intra laboratories (Getachew
et al., 2002). Organic matter digestibility of tomato pomace (62.41%)
was higher than those reported by Chumpawadee et al.
(2007), Besharati et al., 2008 and Mirzaei-Aghsaghali
and Maheri-Sis (2008). Organic matter digestibility of brewers grain
(52.72%) was lower than those fined by Alawa et al.
(1988), Boucque and Fiems (1988). The SCFA production
of tomato pomace (0.8613 mmol) was higher than that reported by Besharati
et al., 2008. The SCFA value of brewers grain in this study
was 0.6870 mmol. Vlaeminck et al. (2004) reported
that total VFA obtained from in vitro rumen fermentation of brewers
grain was 1949 μmol.
The reason that, why energy content and organic matter digestibility of tomato
pomace were higher than that of brewers grain could be due to difference
in chemical composition (especially soluble carbohydrates, CP, NFC, EE, ADF
and NDF) and volume of gas production (Menke and Steingass,
1988 ; Getachew et al., 2004). Blummel
et al. (1999) reported that the gas volume in the bicarbonate buffered
Hohenheim in vitro gas production test reflect SCFA production very closely.
Gas volumes were produced quantitatively and qualitatively as a result of SCFA
production (the amount of fermentative CO2 and CH4 could
be accurately calculated from the amount and proportion of acetate, propionate
and butyrate present in the incubation medium). Thus increasing amount of SCFA
was lead to increase in gas production, which is resulted in high digestibility
and energetic value.
In an overall conclusion the nutritive value (chemical composition, gas production
characteristics, organic matter digestibility, metabolizable energy content
and short chain fatty acids production) of tomato pomace were better than that
of brewers grain. However, both by- products economically can be used as potential
fibrous, energy and protein sources in ruminant nutrition.
This study was carried out as a research project in Animal Sciences in Islamic
Azad University, Shabestar Branch. Authors thanks from Animal Science Laboratories
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