Abstract
The aim of this study was to compare the effect of different dietary supplements (bee pollen, BP; propolis, Pro; and mannan oligosaccharides, MOS) administered continuous or intermittent on productive performance and physiological traits of broiler chickens. A total of 324 unsexed 1-d-old Arbor Acres broiler chickens were divided among 9 dietary treatments with 6 replicate cages per treatment and 6 broiler chickens per cage, assigning experimental units to treatments randomly. Broiler chickens were assigned to the following starter and grower dietary treatments: basal control with no supplementation or basal control diets supplemented with 300 mg BP (BP), 300 mg Pro (Pro), 300 mg BP and 300 mg Pro (BP+Pro), and 0.5 g MOS/kg. Each treatment group was divided into 2, in which the additives were administrated continuous or intermittent. The broiler chickens were vaccinated at d 7, 10, 14, and 21 of age. In the continuous treatment groups, supplementations were given from d 0 to 35, whereas in the intermittent treatment groups, the administration protocol was the following: 3 consecutive days before the day of vaccination (4,5 and 6; 7,8 and 9; 11,12 and 13; and 18,19 and 20 d of age); on the day of vaccinations and 1 d after each vaccination (d 8, 11, 15 and 22 d of age). Thus, supplements were administered for 17 days as 7, 8 and 11 d of age were overlapped because of the vaccination on 7 and 10 d of age. All the supplements administered continuously or intermittently increased (P < 0.05) body weight gain (average 1856 vs. 1641 g) and improved (P < 0.01) feed conversion ratio (average 1.88 vs. 2.24) during the entire period of the study in comparison to the un-supplemented control treatment. Also, dressing percentage was increased (P < 0.05) in all the supplemented treatments compared with the control treatment (an average 70.9% vs. 68.9%). There was no synergistic effect of BP and Pro on growth performance, indicating that either of them is adequate. In general, the natural growth promoters increased red blood cells and hemoglobin (P < 0.012) and decreased triglycerides, cholesterol, urea-N, and creatinine (P < 0.008) as well as aspartate aminotransferase (P=0.047) in broiler chickens. Supplementing BP, Pro, or MOS continuously or intermittently was equally effective in increasing growth performance and dressing percent of broiler chickens. (C) 2014 Elsevier B.V. All rights reserved.