This study was conducted to eva‎luate the effects of different proportion of colostrum to body weight and different feeding times on starter intake, body weight, immunity, physical growth and health of calves. A total of 70 calves (male and female) immediately after birth were weighted and assigned to one of the experimental groups. The experimental groups were: 1- control group (11.25% of BW colostrum in 6 hours: 7.5% (2 hours) + 3.75% (4 hours later), 2- 15% of BW colostrum in 14 hours: 7.5% (2 hours) + 7.5% (12 hours later), 3- 15% of BWcolostrum in 14 hours: 10%( 2 hours) + 5% (12 hours later), 4- 15% of BW colostrum by 3 stage in 14 hours: 5% (2 hours) + 5% (6 houre later) + 5% (12 hours later) and 5- ad-libitum colostrum every 6 hours. In the first three days, the calves were fed with colostrum and transition milk. From day 4, the calves were fed with milk and starter, then they weaned at day 65 of age. Intake of starter measured weekly based on difference between supplied and residue. Physical growth was measured on days 4 and 74 of experiment. Blood samples were taken at hours of 0, 12, 24, 48 and day 28 from the jugular vein 3 hours after morning milk. Calves health was eva‎luated for diarrhea, pneumonia, infectios and digestive problems. The results showed that mean of feed intake was not affected during experimental period (P = 0.07). Weaning weight, total daily gain and daily gain before weaning time did not differ between the experimental groups (P> 0.05). Mean of weight at the end of experimental period, as well as daily gain after weaning were lower in groups 4 and 5 compared to other experimental groups (P = 0.001). Physical growth-related traits were not affected by experimental groups at days 4 and 74 (P> 0.05). Serum concentrations of glucose, total protein, albumin, triglyceride, blood urea nitrogen, aspartate aminotransferase and alanine aminotransferase and serum Brix index were not different between experimental groups (P >0.05). Blood cholesterol concentration was higher in group 3 and 5 compared to other experimental groups (P¬ <0.05). The percentage of monocytes, eosinophils, basophils, hematocrit and hemoglobin concentration, as well as red blood cell count was not affected at days 4 and 14 of the experiments (P> 0.05). The count of white blood cells was not affected by the experimental groups (P> 0.05) at day 4, however group 3 had lower WBC compared to other experimental groups (P <0.05) at day 14. The percentage of neutrophils was higher in group 3 compared to the other experimental groups (P <0.05) at day 4. The percentage of neutrophil was lower (P = 0.007), while lymphocyte was higher (P = 0.008) in groups 3 and 5 compared to the other groups at d 14. The incidence of diarrhea, pneumonia, infectious and gastrointestinal problems did not differ between experimental groups (P> 0.05).

ابراهيم قاسمي ،محد خوروش

امير حسين مهدوي

غلامرضا قرباني ،حميد نصير پور