Tomato pomace: A prospective unconventional feed ingredient

Consumption of poultry meat has consistently increased globally over the years. Poultry is also one of the fastest growing segments of the agricultural sector in India today. Such growth in the poultry industry is having a profound effect on the demand for feed and raw materials. With increasing feed costs the poultry sector has to opt for alternative feed resources to conventional feeds, especially agricultural and industrial by-products. The wastes from the fruit and vegetable industry can be a potential source of newer cheap feed resources. Investigations with regard to the nutritional efficiency, growth performance, and carcass characteristics of broilers fed on diets containing different levels of dried tomato pomace (DTP), with or without enzyme supplementation, have resulted in ground-breaking performances. Dried tomato pomace, a by-product of tomato processing, is an excellent source of α-tocopherol (vitamin E), which is used as an antioxidant in broiler meat. In a feeding study on broilers, no significant differences were observed in body weight and feed per gain in chicks given diets with or without tomato pomace. Tomato pomace could be used as a source of α-tocopherol in broiler diets to decrease lipid oxidation (fat deterioration) during heating and long-term frozen storage of dark meat and to prolong shelf life. Because of the fact that tomato by-products contain high levels of unsaturated fatty acids, the pomace must be defatted without losing vitamin E to minimize its oxidation potential.
Heat stress is a major environmental stress, which may have deleterious effects on growth performance, nutrient availability, immunity, and welfare of broiler chickens. High ambient temperatures could increase the production of reactive oxygen substances (ROS), which may cause damage to critical biomolecules including lipids, proteins, and DNA. This, in turn, could have an adverse effect on animal performance, and meat quality, mainly due to tissue damage and bone loss.Several nutritional approaches such as supplementation of diets with antioxidant vitamins and minerals and phytochemicals have been used to attenuate the negative effects of heat stress. Tomato pomace, a by-product of tomato processing, contains antioxidant compounds including lycopene, folate, vitamin C, β-carotene, α-tocopherol, phenolics, and flavonoids. Lycopene is a strong antioxidant among dietary carotenoids and can prevent the production of ROS and its associated undesirable effects. An inverse relationship between lycopene, tomato, or tomato product intake and the levels of oxidative stress biomarkers has been reported. In fact, tomato powder supplementation linearly increased feed intake, weight gain, feed efficiency, serum concentrations of lycopene, and vitamins A, C, and E and linearly decreased the malondialdehyde levels in the serum, liver, and muscles of Japanese quails under heat stress. In a more recent study, supplementation of tomato puree at the rate of 0.5% in the diet, improved feed intake, weight gain, and feed conversion. At the level of 1%, there was an increase in the total antioxidant capacity and reduced malondialdehyde (MDA) concentration in heat-stressed broilers. It has been shown that incorporation of dried tomato pulp in the diet at a level of 5% exerted antioxidant properties on quail breast meat, whereas supplementation at a level of 10% showed a pro-oxidant effect.Evidence suggests depression in the relative weight of the lymphoid organs and antibody production during heat stress conditions.Studies have shown that supplementing tomato puree enhanced titers against Newcastle disease virus (NDV) and infectious bronchitis virus in broilers reared under heat stress conditions. This could provide immunity as well, but still, there is a scope to find the exact role of tomato pomace against these diseases.
The inclusion of dried tomato pomace in broiler diets is possible if taking into account its low energy value in feed formulation. A lower feed intake has occasionally been observed in young animals, which is probably due more to the higher fibre content than to low palatability since older animals can consume diets with high pomace levels. The lycopene content could actually be an advantage, especially in hot climates, due to its antioxidants. It may be emphasized that for optimal performance, dried tomato pomace should be avoided in very young animals. It can be recommended at up to 5-8% of the diet for growers and up to 10-12% for finishers. However, rates as high as 20% can be used after 4 weeks of age, if the feed is well balanced in energy, with reduced growth and feed efficiency. For slow-growing chickens, dried tomato pomace can be a realistic option.
In the last decades, a lot of research has been done to evaluate the roles of using vegetable by-products. But there is no sufficient report in the scientific literature using these by-products as an alternative resource in poultry nutrition because of their juicy nature. It is well known that pomaces, especially dried tomato pomace, was used in poultry nutrition. It was observed that increased dried tomato pomace levels in both starter and finisher broiler chicken diets resulted in lower live weight, thereby stressing the fact that tomato pomace has a better role as an antioxidant supplement, rather than as a feed ingredient. Because of these kinds of inconsistencies, there is a need to investigate the effects of tomato pomace-supplemented diets on meat quality and shelf life.

by Dr. Himani Ravi, GB Pant University