Abstract: This study was conducted to evaluate of tomato wastes (fresh or silage), cucumber wastes (fresh or silage) as alternative feeds for ruminants using in vitro gas production technique. Rumen liquor was obtained from four Naimey sheep fed on barely and alfalfa hay (slaughter house). The mixtures of rumen fluid with buffer 1: 2 v/v, 30 mL were placed into each syringe, containing the samples. The incubation procedure was repeated three times. The gas production was recorded after 3, 6, 9, 12, 24, 48 and 72 h of incubation. Potential degradability (a+b) and gas production rate (c) were measured. Metabolizable Energy (ME), Net Energy (NE), Organic Matter Digestibility (OMD) and Microbial Protein (MP) were also estimated. Tomato silage had the highest crude protein followed by tomato fresh, cucumber fresh and cucumber silage. There were no significant differences (p>0.05) among forms of wastes in potential degradability (a+b) except cucumber silage had the lowest a+b. The OMD was highest in tomato fresh and lowest in cucumber silage. There were no significant differences between tomato fresh, tomato silage and cucumber fresh but the lowest value of ME recorded with cucumber silage. There were no significant differences (p>0.05) among four forms in NE except in cucumber silage. The present study suggest that tomato waste could be used in the fresh form as alternative feeds for ruminants followed by tomato silage, cucumber fresh and cucumber silage.
INTRODUCTION
In Saudi Arabia, there is now big challenge concerning animal farmers, because a high price of animal feed and ground water is limited for forage cultivation. On the other hand, the increasing consumer demand for animal products, make us to search for other alternatives of feeds. In the Kingdom of Saudi Arabia there are usually significant amounts of by-products from food industry that have either limited or no value as human feed and it is a feasible solution to minimize the problem of feed shortage and can be used as feedstuffs for ruminant animals.
Agriculture by-products that can be used for animal feed as alternative feeds such as tomatoes and cucumbers produced from the greenhouses after harvested either in its fresh form or in the form of silage.
Peel and seeds mixture of tomato by-products called tomato pulp (Alicata et al., 1988). Tomato by-products have high nutritional value particularly in crude protein (Bartocci et al., 1980; NRC, 1984; Mikail, 1997; Soltan, 2002). FAO (1991) reported that tomato by-products from world production after processing are about 2-4 million ton year-1. Fresh tomato waste contained high moisture content approximately 80-84% (El-Hassan, 1999). In fact, there are many type of vegetables by products such as cucumber, carrot, potato, cabbage and etc. can used as alternative feeds for ruminants. Therefore, the objective of the current study was conducted to evaluate tomato and cucumber wastes (fresh or silage) as alternative feeds for ruminants using gas production technique.
MATERIALS AND METHODS
Silage tomato and cucumber wastes procedure: Tomato and cucumber waste were collected from greenhouses after harvested the main yield of tomato and cucumber. Collected vegetable wastes were cleaned to remove any foreign substances and cut to 5-10 cm pieces and then mixed with 5% palm molasses (v/w). The mixtures of Tomato or cucumbers waste with palm molasses were placed in three liter plastic bucket by hand, firmly compressed, closed and strapped to prevent air ingress. Each group was prepared as three replicates and plastic bucket were left for fermentation at room temperature for 30 days. Samples of vegetable wastes silage were opened after fermentation and used for determining of pH, further analyses.
In vitro trial: In vitro gas production technique was conducted according to Menke and Steingass (1988). Rumen liquor was obtained from four sheep fed on barley and alfalfa hay (slaughter house). Buffer solution was prepared according to Onodera and Henderson (1980) and placed in a shaker water bath at 39°C under continuous flushing with CO2. Approximately 200 mg air dry of fresh or silages of tomato and cucumber waste samples were placed into syringe (100 mL, three syringes per sample). The mixture of rumen fluid with buffer 1: 2 v/v, 30 mL were placed into each syringe, containing the samples according to Blummel and Orskov (1993). The incubation procedure was repeated three times. The gas production was recorded after 3, 6, 9, 12, 24, 48 and 72 h of incubation. Cumulative gas production values was fitted to the potential equation, Gas (Y) = a+b (1-exp-ct), where, a is the gas production from the immediately soluble fraction, b is the gas production from the insoluble fraction, a+b is potential degradability, c is the gas production rate constant for the insoluble fraction (b), t is incubation time, according to the model of Orskov and McDonald (1979).
Energy and microbial protein estimation: The energy values of fresh and silages of tomato and cucumber wastes were calculated from the amount of gas produced at 24 h of incubation with supplementary analysis of crude protein, ash, crud fibre and ether extract (Menke et al., 1979; Menke and Steingass, 1988):
ME (MJ kg-1 DM) = 2.2+0.136GP+0.057CP+0.0029CF
OMD (%) = 14.88+0.889 GP+0.45CP+0.0651XA
where, ME is the metabolizable energy, OMD is organic matter digestibility, GP is 24 h net gas production (mL/200 mg DM), CP is crude protein (%DM), CF is crude fibre (%DM), XA is ash (%DM):
where, Gas is 24 h net gas production (mL g-1 DM), CP is crude protein (%DM); EE is Ether extract (%DM), then net energy unit converted to be MJ kg-1 DM.
Microbial Protein (MP) was calculated as g kg-1 OMD according to Czerkawski (1986).
pH measurement: Seventy mililiter of distilled water were added to 35 g of each sample (fresh or silage) in glass conical flask soaked at 4°C. The fresh and silage extracts were filtered through 2 layers of gauze and filter paper. The filtrate was stored at -20°C prior to chemical analysis (Shao et al., 2007) as described by Li et al. (2012). pH values were measured using a digital pH-meter.
Chemical analysis: The fresh and silage samples of tomato and cucumber wastes were analyzed for Dry Matter (DM), Crude Protein (CP), Ether Extract (EE) and ash according to AOAC (1995). Neutral Detergent Fiber (NDF) and Acid Detergent Fiber (ADF) were determined according to Van Soest et al. (1991).
Statistical analysis: All data were analyzed using SPSS packet software was used (SPSS, 2002).
RESULTS AND DISCUSSION
The chemical composition, fiber fractions and pH of tomato and cucumber wastes in two forms fresh and silage are shown in Table 1. Tomato silage had the highest crude protein followed by tomato fresh, cucumber fresh and cucumber silage, the values were 16.69, 14.08, 13.57 and 9.83% for tomato silage, tomato fresh, cucumber fresh and cucumber silage, respectively. The increase of crude protein in tomato silage compared to tomato fresh probably due to the decrease in crude fiber, NFE, NDF and ADF (Table 1). The lower NDF and ADF in ensiled tomato waste was probably due to cell wall degradation by cellulolytic clostridia or acid hydrolysis (McDonald et al., 1991; Baytok et al., 2005). The decrease of crude protein in cucumber silage comparing with cucumber fresh may be due to some crude protein in cucumber silage was converted into ammonia during ensiling (Abarghoei et al., 2011). The increase of crude fiber and cell walls of cucumber silage probably due to the increasing of lignin which protected the fiber degradation by cellulolytic clostridia in ensiling (Abarghoei et al., 2011).
| Table 1: | Chemical composition (% of DM basis), fiber fractions and pH of tomato and cucumber wastes |
| NDF: Neutral detergent fiber, ADF: Acid detergent fiber, NFE: Nitrogen free extract | |
| Table 2: | Cumulative gas produced (mL/200 mg DM) at different incubation times of tomato and cucumber wastes (Mean±SD) |
| *Rumen liquor was collected from four animals three times | |
| Table 3: | Parameters of gas production produced from tomato and cucumber wastes during 72 h incubation (Mean±SD) |
| Cumulative gas production data were fitted to the model of Orskov and McDonald (1979), Gas (Y) = a+b (1-exp-ct), where, a: The gas production from the immediately soluble fraction, b: The gas production from the insoluble fraction, a+b: Potential degradability, c: The gas production rate constant for the insoluble fraction (b), t: Incubation time, a,b,c: Means within a column bearing different superscripts differ (p<0.05) | |
pH values decreased in silage form in both of tomato and cucumber wastes (Table 1). Ensiling of either tomato or cucumber wastes caused decrease the pH due to the lactic acid and volatile fatty acids produced (McDonald et al., 1991; Abarghoei et al., 2011).
Table 2 shows the cumulative gas produced at different incubation times of tomato and cucumber wastes. The values of gas production extent at 72 h were 32.67, 32.00, 31.83 and 28.17 mL for tomato fresh, tomato silage, cucumber fresh and cucumber silage, respectively. There were no significant differences (p>0.05) among forms of wastes in potential degradability (a+b) except cucumber silage had the lowest a+b (Table 3). The values were 31.30, 33.04, 32.96 and 29.91 mL for tomato fresh, tomato silage, cucumber fresh and cucumber silage, respectively. The gas production rate (c) of wastes in four forms is presented in Table 3. The highest value was recorded with tomato fresh followed by tomato silage, cucumber fresh and cucumber silage and the values were 0.09, 0.05, 0.04 and 0.04 mL h-1, for tomato fresh, tomato silage, cucumber fresh and cucumber silage, respectively. The lowest value of potential degradability (a+b) and gas production rate (c) of cucumber silage might be due to the high content of ash, crude fiber and cell walls and its low content of crude protein. There was no significant difference (p>0.05) between tomato fresh and tomato silage in a+b and c and the tomato of two forms (silage and fresh) better than cucumber (silage and fresh). Gas production technique has been widely used to assess the nutritive value of feedstuff, the types of wastes (vegetables, fruits or crops) and tropical plants (El-Waziry et al., 2005, 2007; El-Waziry, 2007; Razligi et al., 2011; Getachew et al., 1998).
The predicted metabolizable energy (ME, MJ kg-1 DM), net energy (NE, MJ kg-1 DM), organic matter digestibility (OMD%) from gas production and microbial protein (MP, g kg-1 OMD) are presented in Table 4. The OMD was highest in tomato fresh and lowest in cucumber silage.
| Table 4: | Predicted of metabolizable energy (ME), net energy (NE), organic matter digestibility (OMD) and microbial protein (MP) in vitro from tomato and cucumber wastes during 72 h incubation (Mean±SD) |
| a-d: Means within a column bearing different superscripts differ (p<0.05), *Calculated according to Czerkawski (1986) | |
The values were 43.94, 40.05, 39.81 and 34.14% for tomato fresh, cucumber fresh, tomato silage and cucumber silage, respectively (Table 4) and there was no significant difference between tomato fresh and cucumber fresh. The predicted ME which calculated from gas production at 24 h incubation were 6.21, 5.76, 5.69 and 2.86 MJ kg-1 DM for tomato fresh, tomato silage, cucumber fresh and cucumber silage, respectively. There were no significant differences between tomato fresh, tomato silage and cucumber fresh but the lowest value of ME recorded with cucumber silage. The same manner was found in OMD and MP (Table 4). There were no significant differences among four forms in NE except in cucumber silage (Table 4). ME and OMD in tomato fresh is agreement with the results of Rashwan (2010) which used artichoke by-products silage and hay.
CONCLUSION
The results of this study seems that tomato wastes in both forms fresh or silage better than that of cucumber fresh or silage in chemical composition, cumulative gas production in vitro , potential degradability, gas production rate, ME, OMD and MP. There was no significant difference between tomato fresh and silage, Therefore the present study suggest that tomato waste could be used in the fresh form as alternative feeds for ruminants followed by tomato silage, cucumber fresh and cucumber silage.
ACKNOWLEDGMENT
The Authors extend their appreciation to the Deanship of Scientific Research at King Saud University for funding the work through the research group project No. RGP-VPP-134.