DIETARY EFFECTS OF CHROMIUM PICOLINATE WITH OR WITHOUT VITAMIN C SUPPLEMENTATION ON DOMESTIC CHICKENS IN THE TROPICAL ENVIRONMENT

Abstract

This study evaluated the effects of dietary chromium picolinate (CrPic) supplemented with or without vitamin C on the physiologic, reproductive and growth responses of broiler chickens, layers and Cocks under high ambient temperature. A total of 640 day-old Cobb 500 broiler chickens, 216 point-of lay Noiler pullets and two-breed sexually matured Cocks (Noiler and White leghorn) of 96 birds each were purchased from a reputable farm. The birds in the phases were assigned to 8 treatments in a completely randomized design (CRD) using a 2 × 4 factorial arrangement (2 levels of vitamin C and 4 levels of CrPic) for phases1 and 2 while those in phase 3 was 2 x 2 x 4 factorial arrangement (2 breeds of Cocks, 2 levels of vitamin C and 4 levels of CrPic). A basal diet was formulated, divided into eight equal portions. Diets 1 to 4 were supplemented with 0.00, 0.40, 0.80 and 1.20 mg/kg CrPic while diets 5 to 8 were supplemented with 200 mg/kg vitamin C, 0.40 mg/kg CrPic and 200 mg/kg vitamin C, 0.80 mg/kg CrPic and 200 mg/kg vitamin C, and 1.20 mg/kg CrPic and 200 mg/kg Vitamin C, respectively. The feeding trial lasted 6 weeks for phase one and 16 weeks for phases two and three. All data collected in the three phases were subjected to statistical analysis using SAS (version 9.2). Results showed that CrPic at 0.80 mg/kg level of supplementation improved significantly (P<0.05) the final body weight (FBW), feed conversion ratio, slaughter weight and antioxidant enzyme status in broilers. Also vitamin C supplementation at 200 mg/kg improved significantly (P<0.05) the FBW. The haematological indices for the broiler birds were stable (P<0.05) across the diets. Dietary supplementation of vitamin C at 200 mg/kg significantly (P<0.05) reduced the aspartate aminotransferase and alanine aminotransferase while 1.20 mg/kg CrPic supplementation produced marked inflammation on the liver and kidney. The result of the laying birds revealed that mean cell volume, mean cell haemoglobin and white blood cells were significantly (P<0.05) increased by the CrPic and there was a significant (P<0.05) reduction in the blood concentration of glucose and cholesterol at 1.20 mg/kg CrPic. With reference to the Cocks, the results revealed significant (P<0.05) breed differences in the brain Acetylcholesterase (AChE) and Total Protein (TP) levels. Diets containing CrPic without vitamin C significantly (P<0.05) elevated the AChE activities in all the brain regions while the TP was significantly (P<0.05) reduced. Supplementation of CrPic above 0.40mg/kg diet negatively (P<0.05) affected the brain parameters studied while vitamin C played a neuro- protective role against the CrPic-induced cognitive effects. Furthermore, the interactions of 0.40 mg/kg CrPic with or without vitamin C significantly (P<0.05) influenced the gonadal and extra-gonadal weights, and semen characteristics, with Cocks fed diets with vitamin C showed higher values. It could be concluded that 0.40 mg CrPic/kg diet with or without vitamin C alleviated the effects of heat stress on domestic chickens raised under high ambient temperature without negatively impacting on their normal growth performance, physiologic, reproductive and general health status.