PERFORMANCE AND PHYSIOLOGICAL ASPECTS OF BROILER CHICKS FED DIETS CONTAINING VARIOUS LEVELS OF CANOLA MEAL

One hundred and fifty day–old Hubbard broiler chicks were used to investigate the effect of including low canola meal (Brassica campestris cv. Pactol) into broiler diets on their performance, internal organs relative weights and histology of liver and thyroid gland and economical efficiency throughout different growth stages. Birds were fed three periodical diets; starter, grower and finisher, based on corn- soybean meal. Canola meal (CM) was included into diets with levels of 0 (control), 10%, 12.5%, 15%, and 20%. The results indicated that, feed intake values were not affected by including canola meal into diets at different intervals (0-21, 22-32; 33-42 day), however feed consumption of chicks fed 20% canola was significantly lower for the entire experimental period. Body weight gain of chicks fed 20% canola meal were significantly lower than control ,while including canola meal up to 15% has no effect on body weight. Feed conversion ratio was not affected by 5% inclusion of canola meal, however, a negative but insignificant effect was observed with level of 10%. The relatives weight of each of dressing carcass, abdominal fat, liver, and spleen were not affected by including canola meal into diets. Thyroid gland percentage significantly increased due to incorporating canola meal into diets. Histological examination of liver and thyroid gland sections showed slight changes in the hepatocytes and thyroid follicles coincident with the level of canola meal inclusion level. In spit of included graded levels of canola meal into diets reduced total feed cost, the net revenue value of high inclusion level 20% (4.66LE) was lower than the control (4.9LE). As well, European efficiency factor and Performance index showed better values for control than canola meal feeding groups. It is concluded that 15% of CM in broiler diet is sufficient to obtain good performance and economical benefits without adverse effects on physiological status of birds.