Abstract #M153

# M153
Effect of different times of super-conditioning in pelleted starter on nutrient digestibility and performance of pre-weaned calves.
E. Soltani1, A. Naserian1, R. Valizadeh1, A. Tahmasebi1, M. Malekkhahi2, B. Kim*3, A. Rahimi1, 1Animal Science Department, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran, 2Dordaneh Razavi, Mashhad, Iran, 3College of Animal Life Sciences, Kangwon National University, Chuncheon, Republic of Korea.

The objective of this study was to investigate the effects of conditioning time during pelleting process on performance, apparent digestibility, rumen fermentation, and blood metabolites of pre-weaned calves fed with pelleted starter diet. Thirty-six 3-d-old Holstein dairy calves (41 ± 0.5 kg of BW) were randomly assigned to one of 3 experimental diets: T1) starter without super- conditioning (Control); T2) starter with super-conditioning at 85°C for 2 min; and T3) starter with super-conditioning at 85°C for 4 min. All calves were weaned on age 56 d and remained in the study until d 70 of experiment. Data were analyzed by GLM procedure of SAS (P < 0.05) using a completely randomized design with 12 replications for every treatment. Starter intake, feed efficiency and fecal score were not affected (P > 0.05) by super-conditioning time during the pre- or post-weaning periods, but average daily gain (ADG) significantly increased (P < 0.05) in calves fed with T3 during the post-weaning period (0.92, 0.98 and 1.16 kg/d in T1, T2 and T3, respectively). The pH, ammonia nitrogen, total VFA and the molar proportions of acetate, propionate and butyrate were not different (P > 0.05) among treatments, but ammonia nitrogen (6.76, 5.81 and 5.44 mg/dL in T1, T2 and T3, respectively) and molar proportions of propionate (33.81, 36.12 and 39.72 mol/100 mol total VFA in T1, T2 and T3, respectively) were shown high tendency (P = 0.085) in calves fed with T3 during the post-weaning period. Body measurements were not affected (P > 0.05) by the treatments. The concentration of blood glucose and insulin was higher (P < 0.05) in calves fed with T3. Apparent digestibility of dry matter, starch, crude protein, NDF and ADF were not different (P > 0.05) among treatments during the pre-weaning period, but starch and dry matter digestibility during the post-weaning period were significantly increased (P < 0.05) in starter T3 (76.44, 78.83 and 79.59% for dry mater and 94.71, 96.63 and 97.4% for starch digestibility in T1, T2 and T3, respectively). Results of the present study indicated that enhancing of super-conditioning time from 2 to 4 min during pelleting process improved ADG and apparent nutrient digestibility in post-weaning period of dairy calves.

Key Words: performance of calf, nutrient digestibility, super-conditioning time