Tomato wastes

Tomato pomace, the waste from paste production factories, is a valuable source of protein and energy Use of this by-product can reduce waste as well as decrease contamination from the disposal of resulting products; thus, tomato pomace represents a cheap and suitable resource for poultry feeding (Persia et al., Reference PERSIA, PARSONS, SCHANG and AZCONA2003; Kavitha et al., Reference KAVITHA, RAMANA, RAMA PRASAD, REDDY and REDDY2004). Sogi et al. (Reference SOGI, ARORA, GARG and BAWA2002) estimated the amount of the protein and fat in tomato pomace to be 22 and 10%, respectively, and the authors suggested a possible beneficial use of this by-product as a dietary ingredient for poultry.

Squires et al. (Reference SQUIRES, NABER and TOELLE1992) investigated the effect of processed tomato pomace (which may have been subjected to alkali, heat, water and acid) on the performance of broiler chickens and indicated that the processing of tomato pomace with alkali increased the weight gain of broilers. In research conducted by Jafari et al. (Reference JAFARI, PIRMOHAMMADI and BAMPIDIS2006), chickens fed with alkaline-treated tomato pomace had higher growth performance than those fed urea- and enzyme-treated tomato pomace. Moreover, it was found that tomato pomace can be used in the diet of broiler chickens due to its high amount of minerals, protein and fat (Petrenko and Banina, Reference PETRENKO and BANINA1984).

The effect of tomato pomace on the palatability of the diet and improvement of performance in broiler chickens has been reported in many studies (Persia et al., Reference PERSIA, PARSONS, SCHANG and AZCONA2003; Ayhan and Aktan, Reference AYHAN and AKTAN2004), and researchers have proposed the use of tomato pomace as a nutritious ingredient in broiler diets. These researchers reported that using tomato pomace in broiler diets resulted in a reduction in the percentage of abdominal fat pad, and this was attributed to the high levels of fibre in tomato pomace. In addition, the presence of the powerful antioxidant, lycopene, which is produced from heat treatment in tomato pomace, can be effective in reducing the synthesis of lipids and reducing oxidative damage (Kumar et al., Reference KUMAR, SUDHEESH, USHAKUMARI, KUMAR, VIJAYKUMAR and VIJAYALAKSHMI1997; Kavitha et al., Reference KAVITHA, RAMANA, RAMA PRASAD, REDDY and REDDY2007). Recently, Hosseini Vashan et al. (Reference HOSSEINI VASHAN, YAGHOBFAR and GOLIAN2016) investigated the effect of tomato pomace, canola oil, soybean and animal fat on the performance, carcass constituents and bone parameters of broiler chickens under heat stress conditions. The supplementation with tomato pomace and canola oil improved the weight of spleen, bursa and bone parameters and reduced ventricular fat. The addition of 3 and 5% tomato pomace to the diet increased the percentage of dry matter, outer wall thickness and diameter of the canal of mid-diaphysis (the central shaft of long bones). These researchers linked the positive effect of tomato pomace to the presence of lycopene and its antioxidant properties.

The effects of different levels of dried tomato on performance, egg quality and blood metabolites of laying hens have been investigated. Results showed that total protein, cholesterol, high density lipoproteins (HDL), low density lipoproteins (LDL), albumin, glucose and triglyceride were not significantly affected by different levels of tomato pomace supplementation (Salajegheh et al., Reference SALAJEGHEH, GHAZI, MAHDAVI and MOZAFARI2012). In general, adding tomato waste as an alternative feed up to 19% of diet can be used without a negative effect on egg production and performance (Salajegheh et al., Reference SALAJEGHEH, GHAZI, MAHDAVI and MOZAFARI2012). In research by Jafari et al. (Reference JAFARI, PIRMOHAMMADI and BAMPIDIS2006), the application of 10% tomato pomace in the diet of laying hens reduced the production and weight of eggs compared to a control diet. Further, Asadollahi et al. (Reference ASADOLLAHI, KARIMI and MANSURI2014) used tomato waste at the levels of 0, 5, 10 and 15% in broiler diets and concluded that using up to 10% tomato waste in a broiler diet resulted in the best meat quality.

Rahmatnejad et al. (Reference RAHMATNEJAD, BOJARPOUR, MIRZADEH, CHAJI and MOHAMMADABADI2009) investigated the effect of different levels of tomato waste on blood indices of broiler chickens, and the results showed that highest HDL level was found in chickens fed diets containing 16 and 24% tomato wastes. Nikolakakis et al. (Reference NIKOLAKAKIS, BANAKIS, FLOROU-PANERI, DOTAS, GIANNENAS and BOTSOGLOU2004) investigated the effect of tomato pomace (0, 5 and 10%) on the performance and characteristics of quail carcasses. The findings showed that final bodyweight, feed intake and feed conversion ratio were not significantly different when measured at 42 days of age. The colour of the skin of the breast and thigh was darker in quail fed diets containing 5 and 10% of tomato pomace compared with the control diet. Meat colour (without skin) and the level of meat fatty acids were not affected by the treatments. This study demonstrated that tomato pomace could be used at up to 10% of the diet without any adverse effect on performance and carcass characteristics of quail. More recently, Lira et al. (Reference LIRA, RABELLO, MOHAUPT MARQUES LUDKE, FERREIRA, LANA and VALERIO LANA2010) examined the effect of feeding different levels of tomato waste on growth performance and meat production characteristics of broiler chickens in a completely randomised design with five treatments (0, 5, 10, 15 and 20% of tomato waste in the diet). Results showed that using tomato waste in broiler diets during the period 1 to 28 days of age may cause weight loss and lowered feed conversion ratio; however, using 20% of tomato waste in the diet from 29 to 42 days of age improved slaughter weight and feed conversion ratio of the birds without an any adverse effect. Based on the conducted research, tomato by-products can be used as an alternative feedstuff in both meat-type birds (chickens and quail) and layers at inclusion levels of up to 10% without negative effects on productive performance.

Olive wastes

Over 65% pf the world's olives are produced in the Mediterranean. Different technologies are used to extract oil from olives and during this process and a high amount of waste results. This includes olive meal, olive cake, olive water, olive leaf, olive molasses and olive pulp, all of which can be used in poultry nutrition after the removal of stones (Amici et al., Reference AMICI, VERNA and MARTILLOTTI1991; Abo Omar, Reference ABO OMAR2005).

Olive pulp is an important waste from olive cake or the raw material remaining from olive oil extraction, which is used to produce fuel, with the majority of it converted to waste (Abo Omar et al., Reference ABO OMAR, OTTOMAN, ABU BAKER and ZAAZAA2003). The use of the by-products from olive oil extraction represents a cheap feed source for poultry (Sadeghi et al., Reference SADEGHI, TEIMOURI YNSARI and ANSARI-PIRSARAI2009). Olive pulp (high in oil and water content) is rich in energy and fatty acids, oleic acid (62.4%), linolenic acid (18.2%), linoleic acid (1.1%) and palmitoleic acid (2.7%) (El Hachemi et al., Reference EL HACHEMI, EL MECHERFI, BENZINEB and SAIDI2007). The drier and more concentrated olive meal is another by-product and is high in oleic acid (73%), palmitic acid (13%) and linoleic acid (7%), and according to many studies, this olive meal can be successfully used in poultry diets as a suitable, economically-efficient and environmentally-friendly source of nutrition (Ranalli et al., Reference RANALLI, POLLASTRI, CONTENDO, DI LORETO, IANNUCCI, LUCERA and RUSSI2002; Tufarelli et al., Reference TUFARELLI, INTRONA, CAZZATO, MAZZEI and LAUDADIO2013; Cayan and Erener, Reference CAYAN and ERENER2015; Sateri et al., Reference SATERI, SEIDAVI, BOUYEH, NEUMANN, KUTZLER, LAUDADIO, LOPERFIDO and TUFARELLI2017).

In a recent study, Sateri et al. (Reference SATERI, SEIDAVI, BOUYEH, NEUMANN, KUTZLER, LAUDADIO, LOPERFIDO and TUFARELLI2017) examined the effects of different levels of olive meal (0, 2, 4, 6 and 8%) and enzymatic supplements (mixture of β-glucanase, phytase and hemicellulase) in the diet of broiler chickens. Their results showed that, at the end of a 42-day feeding period, there were no significant differences among treatments in terms of carcass yield, bodyweight, feed intake, and feed conversion ratio. However, antibody titres, after vaccination against infectious bronchitis virus (IBV) and Gumboro disease, were higher in birds fed the diet with 4% of olive meal. In addition, the application of enzyme supplements was not necessary to achieve higher performance from the olive meal-containing diet. Sayehban et al. (Reference SAYEHBAN, SEIDAVI, DADASHBEIKI, GHORBANI, ARAÚJO and ALBINO2015) investigated the effect of olive meal and enzyme supplements on the gastrointestinal tract, immunology and haematological response of broiler chickens. They showed that adding 10% of olive meal to the diet increased the relative weight and length of the jejunum. Furthermore, enzyme-processed olive meal reduced jejunum and caecum length, serum triglycerides and cholesterol. The use of olive pulp improved the size of gastrointestinal tract, while processing olive pulp with enzyme reduced the gastrointestinal size and serum lipid levels. In a recent trial, Sayehban et al. (Reference SAYEHBAN, SEIDAVI, DADASHBEIKI, GHORBANI, ARAÚJO and ALBINO2016) studied the effect of two levels of olive meal (5 and 10%), two types of olive meal processing (with and without enzymes) on performance and economic parameters of broiler chickens. The results showed no significant effect between the diet treatments and the unsupplemented control, with different levels of olive meal for all evaluated traits. Enzyme-processed olive pulp improved feed efficiency in broilers, but, overall, enzyme application had no significant effect. Studies by Cayan and Erener (Reference CAYAN and ERENER2015) assessed the effect of feeding olive leaf powder on some productive characteristics of laying hens. In this study, levels of 0, 1, 2 and 3% olive leaf powder were included in diet for eight weeks. Results showed that olive leaf powder had no significant effect on feed intake, egg weight, egg performance and feed conversion ratio, but the consumption of olive leaf powder caused an increase in carcass weight. Supplementation resulted in a darker yolk colour without affecting its quality, and yolk cholesterol content decreased by 15%.

Afsari et al. (Reference AFSARI, MOHEBBIFAR and TORKI2014) studied the effect of olive pulp (higher in water content) supplemented with probiotics on performance, egg quality and blood parameters of native laying hens. Their findings showed no significant difference among the treatments, including olive pulp compared to the control, in regard to egg production, egg size, whereas feed intake and feed conversion ratio were improved by experimental treatments. In addition, the olive pulp diet significantly reduced blood cholesterol and HDL, whereas no significant differences on the count of blood cells and monocyte percentage were observed. In general, it was found that using 16% of olive pulp in laying hens diet did not have negative effect on performance and resulting in a reduction of feeding costs.

Jafari et al. (Reference JAFARI, CHAJI, BOUJARPOUR, MOHAMMADABADI and SALARI2012) investigated the effect of different levels of olive pulp and enzyme mixture on digestibility and performance of broiler chickens. In their study, 0, 5, 10 and 15% olive pulp were used. Results showed that adding olive pulp to broiler diets significantly increased feed intake and body weight of birds, and chickens fed a diet including 10% of olive pulp had the best performance. Rabayaa et al. (Reference RABAYAA, ABO OMAR and OTHMAN2001) examined the application of olive pulp in broiler diets, and their results demonstrated that including olive pulp up to 7.5% of diet increased the body weight of chickens, feed intake and feed conversion ratio, but increasing olive pulp level above 7.5% had a negative effect on the mentioned traits. In a study by Abo Omar (Reference ABO OMAR2000), the use of olive pulp numerically increased dry matter feed intake and digestibility in broiler chickens, but this increase was not statistically significant. Furthermore, Abo Omar et al. (Reference ABO OMAR, OTTOMAN, ABU BAKER and ZAAZAA2003) showed that the use of antibiotics in feed significantly increased the positive effects of olive pulp in broiler diets, and the weight and feed intake of chickens fed antibiotic-treated diets were more favourable than the control.

More recently, Zangeneh and Torki (Reference ZANGENEH and TORKI2011) reported that feeding different levels of olive pulp (0.0, 4.5 and 9%) and β-mannanase enzyme (0 and 0.05%) gave similar feed conversion ratio and feed intakes in laying hens. Hens fed a diet containing 9% olive pulp plus the mannanase enzyme produced heavier eggs than the other groups. The researchers concluded that the use of 9% olive pulp in laying hens diet had positive effects on egg production.

In general, olive wastes can be added to broiler (at levels of 10%) and laying hen (at levels of 9%) diets with no adverse effect on the bird's performance. Dietary inclusion of olive by-products can have beneficial effect on laying hens' performance in terms of egg weight, yolk index, blood triglycerides and egg-yolk cholesterol.

Date wastes

Dates (Phoenix doctylifera) are a valuable source of vitamins (mainly vitamin A and B groupings) and minerals (K, Ca and I). Researchers demonstrated that the waste (dried pulp and pits of dates) can be used as poultry feed (Kamel et al., Reference KAMEL, DIAB, ILIAU and SALMAN1981; Salarmoini and Fooladi, Reference SALARMOINI and FOOLADI2006). Hiti and Rous (Reference HITI and ROUS1978) investigated the effect of applying date waste without stones in a corn-based diet. In this study, including 5 to 15% waste dates in broiler diets improved the growth traits, especially increasing feed intake. Kamel et al. (Reference KAMEL, DIAB, ILIAU and SALMAN1981) used 0, 5, 10 and 15% of date wastes in broiler diets and indicated that using date wastes in replacement for corn did not significantly affect the growth of chickens. Looking at higher levels of inclusion, Zaghari et al. (Reference ZAGHARI, TAHERKHANI, GHASEMI and SHIVAZAD2009) used 0, 10, 20 and 30% of date pits with a multi-enzyme in broiler diets and showed that this supplementation did not have a significant effect on final bodyweight. Feed conversion ratio of chickens fed 10% date pits in the diet was better than the other treatments. In the same study, gizzard weight was higher in birds fed date pits and cholesterol and triglycerides in blood were decreased with increasing dietary levels.

Hussein and Alhadrami (Reference HUSSEIN and ALHADRAMI2003) examined the effect of a diet containing date pits on the growth and feed intake of broiler chickens in two different experiments. The first trial was performed on Hubbard broiler chickens fed three types of diet: control, 10% uncooked date pits or 10% cooked date pits. Body weight of chickens fed 10% raw date pits significantly increased compared to the control-fed birds. In the second experiment, four levels of raw date pits (0, 10 15% and 20% of diet) were fed to broilers. The results showed that different levels of date pits did not significantly affect bodyweight, feed intake and feed conversion ratio during the starter and grower periods of broilers. Including date waste in broiler diets during the final growing period at levels of 10% increased weight gain and feed intake of chickens (Hussein et al., Reference HUSSEIN, ALHADRAMI and KHALIL1998).

Sundu et al. (Reference SUNDU, KUMAR and DINGLE2006) investigated the effect of date pit powder (dehydrated form) in broiler diets. Supplying date pit powder at levels up to 40% of the diet had no negative effect on growth and feed intake of chickens, although digestion was reduced due to the high fibre content of diet. In this study, the immune response of chickens was improved compared to the control. Moreover, the number of pathogenic bacteria decreased and the number of beneficial bacteria increased in the gut of birds fed diets with date pit powder. The authors suggested that the use of date pit powder in broiler diets was beneficial in reducing the environmental problems associated with the disposal of these materials and can reduce the cost of poultry feed. Broiler trials have been reported by Zanu et al. (Reference ZANU, ABANGIBA, ARTHUR-BADOO, AKPARIBO and SAM2012) using different levels of date wastes in the diet, at 0, 5, 10 and 15%. Feeding 15% of date pit cake caused major weight loss compared to controls, while using 5 and 10% date pit cake resulted in 8.6 and 13.6% weight losses compared to control, respectively. The use of date pits cake had no effect on the birds’ haematological parameters, except for changes in haemoglobin concentration. Another group of researchers reported that using 40% date pit powder with added methionine and lysine in the diet had beneficial effects in broilers (Panigrahi and Powell, Reference PANIGRAHI and POWELL1991).

Recently, Tareen et al. (Reference TAREEN, WAGAN, SIYAL, BABAZADEH, BHUTTO, ARAIN and SAEED2017) examined the influence of different levels of date pits on the growth performance of broiler chickens. In this study, diets with 0, 1%, 2, 3, and 4% date pits were used for six weeks. The highest feed and water intakes were seen in birds fed the control-diet compared to date pits treatments. The best feed conversion ratio was observed in broilers fed 3 and 4% of date pits; moreover, and these diets resulted in highest carcass weight.

The date palm, as well as providing oil production from the kernel for human use, results in waste from the pressings, resulting in meal available for animal feed use. Alshelmani et al. (Reference ALSHELMANI, LOHA, FOOD, SAZILIA and LAUFA2016) evaluated the effects of different levels (0, 5, 10 and 15%) of palm kernel cake fermented with Paenibacillus polymyxa ATCC842 in broiler diets and concluded that using up to 15% palm kernel cake had no negative effects on digestibility in the diet and could be effective in reducing poultry feed costs.

The inclusion of palm kernel meal in the diet can be maximised, provided the diet is balanced, particularly in amino acids and metabolisable energy. As research has shown that its supplementation up to 40% did not have negative effects on the bodyweight of broilers, this may encourage poultry farmers, especially in palm kernel meal producing countries, to use more of this ingredient in commercial rations due to its cost effectiveness and possibility of reducing environmental pollution. However, its fibre content needs to be taken into account to prevent nutrient dilution.

Sunflower meal

Sunflower meal is a by-product of sunflower seed oil extraction, which is mainly used as a protein and fibre source in poultry diets (Laudadio et al., Reference LAUDADIO, BASTONI, INTRONA and TUFARELLI2013; Reference LAUDADIO, CECI, LASTELLA and TUFARELLI2014a; Reference LAUDADIO, INTRONA, LASTELLA and TUFARELLI2014b; Baghban-Kanani et al., Reference BAGHBAN-KANANI, HOSSEINTABAR-GHASEMABAD, AZIMI-YOUVALARI, SEIDAVI, AYAŞAN, LAUDADIO and TUFARELLI2018). It has relatively high levels of fibre, including insoluble fibre from non-starch polysaccharides, and is deficient in certain essential amino acids, which must be added to feed to compensate. Musharaf (Reference MUSHARAF1991) used six different levels (0, 5, 10, 15, 20 and 25%) of sunflower seed meal in diets supplemented with lysine and methionine, for broilers. The results of this study showed that a diet containing 25% sunflower seed meal, along with lysine and methionine, could be successfully used without reducing performance of chickens. Araújo et al. (Reference ARAÚJO, DA SILVA ARAÚJO, PETROLI, DE LAURENTIZ, DE ALBUQUERQUE and DE TRINDADE NETO2011) assessed the effect of adding sunflower meal in a diet formulated based on total digestible amino acids, on broilers from 22-42 days of age. The findings showed that the addition of 15% sunflower meal in the diet reduced the feed conversion ratio in birds. Further, the inclusion of sunflower meal did not have any adverse effect on carcass traits of chickens, but did increase digesta viscosity, which needs to be addressed via the use of a suitable feed enzyme.

Ibrahim and Zubeir (Reference IBRAHIM and ZUBEIR1991) investigated the effect of different levels of sunflower seed meal in feed (0, 10, 20 and 30%) for broiler chickens. The authors showed that there was no significant difference among treatments in terms of bodyweight, feed intake, feed conversion ratio and relative weight of the liver and spleen. The high content of fibre in sunflower seed meal did not have any negative effect on feed intake, and the researchers stated that adding sunflower seed meal at up to 30% of diet had no adverse effect on broilers. Accordingly, Shi et al. (Reference SHI, LU, TONG, ZOU and WANG2012) reported that the use of sunflower meal in poultry diets did not have a negative impact on bodyweight, feed intake, egg production or feed conversion ratio. Results from trials run by Khan et al. (Reference KHAN, SARDAR and SIDDQUE2006) demonstrated that adding sunflower meal to poultry diets resulted in an increase of the length of jejunum and ileum villi, most likely due to the higher fibre in the feed.

Araújo et al. (Reference ARAÚJO, ALBINO, ROSTAGNO, HANNAS, PESSOA, MESSIAS, LELIS and RIBEIRO2014) evaluated the effect of different levels (0, 8, 16 and 24%) of sunflower meal in broiler diets from 21 to 42 days of age. They found that that adding sunflower meal to the diet up to 8% increased the weight of broilers but using higher levels (16 and 24%) had an adverse effect on performance traits. Tavernari et al. (Reference TAVERNARI, ALBINO and MORATA2008) reported that sunflower meal inclusion did not affect the performance and carcass yield in broiler chickens. More recently, Sangsoponjit et al. (Reference SANGSOPONJIT, SUPHALUCKSANA and SRIKIJKASEMWAT2017) found that the dietary inclusion of different levels of sunflower meal (0, 4, 8 and 12%) did not have a significant effect on the productive performance of broiler chickens. The differences among treatments were not statistically significant in terms of bodyweight traits, feed intake, conversion ratio, mortality, European production efficiency factor or carcass yield. Based on these findings, it can be concluded that sunflower meal can be successfully included in layer and broiler diets to replace up to 30% of soybean meal, depending on the sunflower meal nutritional profile (especially crude fibre level), type of diet, nature of the other ingredients and exogenous enzymes supplementation.