Document Type : Research Articles
Authors
Department of Animal Science, University of Mohaghegh Ardabili, Ardabil, Iran
Abstract
Introduction: In recent years, feed shortages have become a serious concern in animal nutrition, especially in developing countries. As a result, alternative feed resources have gained increasing attention. Among these, crop residues and fruit or vegetable processing by-products are widely considered. Using these materials can significantly reduce feed costs and improve overall economic efficiency. Additionally, their use helps address environmental concerns by reducing the accumulation of organic waste. Tomato pomace is a by-product of tomato paste and sauce production. It serves as a valuable protein supplement due to its suitable protein content and can also be used as an energy source in ruminant diets. Studies show that dry tomato pomace contains 20-25% crude protein, 9-12% crude fat, and 57-67% neutral detergent fiber. It also provides essential vitamins such as B1, B2, and A. Moreover, tomato pomace is rich in carotenoids, particularly lycopene, as well as vitamins C and E, which contribute to its antioxidant properties when used in animal feed. Enzyme supplement preparations, which contain Taninase enzyme is commonly employed in the food industry. These enzyme can be used in research to enhance the digestibility of feed ingredients, including tomato pomace, by addressing its nutritional limitations.
Materials and Methods: To conduct this experiment, 30 Moghani male lambs with an average age of 5 months and an average body weight of 24 ± 0.6 kg were used. The animals were randomly assigned to five treatment groups, each with six replicates. Dry matter intake was calculated based on the difference between the offered and refused feed. The dry matter content of both the distributed and residual feed was taken into account. Lambs in each group were individually weighed every two weeks using a digital scale. Body weight gain was calculated based on the difference between the initial and final weights recorded during each weighing period. The feed conversion ratio (FCR) was calculated periodically by dividing feed intake (kg) by body weight gain (kg). Blood samples were collected on days 30 and 60 to measure biochemical and enzymatic parameters. These included glucose, cholesterol, triglycerides, total protein, HDL, BUN, and MDA, as well as liver enzymes such as alanine aminotransferase (ALT), alkaline phosphatase (ALP), and aspartate aminotransferase (AST), along with total antioxidant capacity (TAS). All measurements were performed using an automated biochemical analyzer andstatistical analysis of the experimental data was performed using SAS software (version 9.1)
Results and Discussion:The treatments had no significant effect on weight gain, feed intake, or feed conversion ratio, although the highest FCR was observed in Treatment 4 (7.5% tomato pomace + enzyme). However, the sampling period significantly influenced all performance traits measured. The improved feed conversion ratio in Treatment 4 (7.5% tomato pomace + enzyme) is likely due to enzymatic breakdown of the cell wall, enhancing nutrient availability, including protein. Tomato cell walls contain cellulose, hemicellulose, and pectin, which can reduce digestibility and increase feed intake while limiting weight gain. Nutrient digestibility was influenced by the experimental treatments. Variations in the reported nutritional value of tomato pomace across studies may be attributed to differences in its chemical composition, processing methods, and incubation techniques. Feeding varying levels of tomato pomace, with or without enzyme supplementation, had no significant effect on serum glucose, cholesterol, triglycerides, HDL, BUN, or malondialdehyde (MDA) concentrations. Overall, limited studies have investigated the effects of tomato pomace, alone or in combination with enzymes, on blood parameters in animals. The lack of significant differences in blood indices may be attributed to increased ruminal ammonia and reduced microbial protein synthesis following higher tomato pomace intake, which can lead to elevated blood urea nitrogen (BUN) and potential weight loss. Tomato pomace, with or without enzyme supplementation, had no significant effect on liver enzymes (ALT, ALP, AST), although a slight increase in ALP activity was observed in response to enzyme-treated diets. The lack of significant effects on liver enzyme activity following the consumption of tomato pomace, with or without enzyme, likely indicates the absence of anti-nutritional factors in tomato pomace. This suggests that liver function remained unaffected, with enzyme levels comparable to those of the control group.
Conclusion: The results of this study indicate that feeding tomato pomace at the experimental levels did not negatively affect the parameters measured in fattening lambs. Furthermore, the addition of enzymes to the diet improved certain functional parameters, such as feed conversion ratio and weight gain.
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