Evaluation of Different Levels of Canola Meal on Performance, Organ Weights, Hepatic Deiodinase Gene Expression and Thyroid Morphology in Broiler Chickens

Abstract

This study was carried out to determine the effects of dietary inclusion level of canola meal (CM) on performance, organ weights and hepatic type I deiodinase gene expression in broilers. A completely randomized design with 4 levels of CM (0, 10, 20 and 30%) as a substitute for soybean meal (SBM) was utilized with 5 replicates of 9 birds each. The results showed that body weight gain (1 to 42 d) decreased linearly (P＜0.01) as the inclusion of CM increased. An increase in dietary level of CM also resulted in a linear (P＜0.05) increase in feed conversion ratio (1 to 42 d). Proportion of thyroids (P＜0.05) and liver (P＜0.01) increased linearly with increased levels of CM. A significant linear increase in right ventricular weight: total ventricular weight ratio (P＜0.01) and heart weight (P＜ 0.05) were observed by substituting CM for SBM. The concentration of plasma triiodothyronine and triiodothyronine: tetraiodothyronine ratio decreased linearly (P＜0.01) with increasing level of CM. Expression of hepatic type I deiodinase gene (D1) decreased linearly (P＜0.01) as inclusion level of CM in diets increased. Moreover, increasing linear (P＜0.01) and quadratic responses (P＜0.05) were observed in follicles number and epithelial thickness in broilers thyroids followed by increased levels of CM. In addition, increases in dietary CM inclusion led to a linear (P ＜0.01) increase in thyroid follicles diameters. In conclusion, the results of this study indicate that feeding increasing CM inclusions from 0 to 30% negatively affect growth performance of broiler chickens. From this study, it can also be concluded that substitution of CM for SBM adversely interferes with thyroid and liver functions and decrease D1 gene expression, likely because of higher dietary concentration of glucosinolates.

Nutritional Impact of Canola Meal on Performance, Blood Constituents and Immune Response of Broilers

“…In this respect, Aljuobori et al (2016) suggested that glucosinolates in CM may destroy cellular T 3 receptors and thus increase the thyroid hormones level in blood. In contrary to our results, Taraz et al (2006); Mikulski et al (2012); Payvastegan et al (2017) indicated that an increasing of inclusion levels of CM was followed by plasma T 3 concentrations reduction. However, Taraz et al (2006); Payvastegan et al (2017) reported no significant differences in plasma T 4 among all experimental groups.…”

“…In contrary to our results, Taraz et al (2006); Mikulski et al (2012); Payvastegan et al (2017) indicated that an increasing of inclusion levels of CM was followed by plasma T 3 concentrations reduction. However, Taraz et al (2006); Payvastegan et al (2017) reported no significant differences in plasma T 4 among all experimental groups. They attributed these discrepancies to differences in glucosinolates content in CM, diet ingredients, composition of gut microorganism besides, the extent of glucosinolates degradation by heat during the oil extraction process (Woyengo et al, 2011).…”

“…In this connection, Mnisi and Mlambo (2018) with quail and El-Medany and El-Reffaei (2015) with growing rabbits attained the same result. In contrary with our results, Payvastegan et al (2017) reported no significant differences in plasma concentrations of cholesterol and HDL cholesterol in broilers receiving diets containing different levels of CM up to 30%. In the same line Payvastegan et al (2013) reported no significant differences in plasma concentrations of cholesterol and HDL in broilers receiving diets containing different levels of solvent extracted CM up to 20%.The higher HDL fraction (P < 0.05) and lower LDL cholesterol (P > 0.05) of CM fed groups compared to the control indicated the positive effect of CM in lowering serum cholesterol content.…”

Partial replacement of soybean products with canola meal in indigenous chicken diets: size of internal organs, carcass characteristics and breast meat quality

“…The function of the liver is to detoxify chemicals and metabolize drugs. It is known that the size of the liver increases in response to higher levels of chemical compounds requiring detoxification (Payvastegan et al, 2017 ). It was expected that higher levels of CM inclusion would induce higher liver activity leading to birds with bigger livers than those reared on the CM0 diet.…”

“…However, the presence of anti-nutritional factors ( ANF ) such as fibre (12%) and glucosinolates (3.8 µmol/g) (Disetlhe et al, 2018 ) in CM could hinder growth by interfering with nutrient digestion and absorption (Wickramasuriya et al, 2015 ) as well as carcass composition and meat quality in indigenous chickens. Indeed, these ANFs have been reported to reduce growth performance in broilers (Payvastegan et al, 2017 ) and quails (Moraes et al, 2015 ). Glucosinolates interfere with thyroid hormone synthesis, causing liver damage and appetite depression (Tripathi and Mishra, 2007 ).…”