INTRODUCTION Advances in research and rigorous genetic selection over the last 3 decades have successfully led to signifi- cant increases in the overall posthatch performance of broiler chickens. Unfortunately, these accomplishments have been associated with concomitant musculoskeletal imbalances largely as a result of the development of bones in these birds that are more porous and that are less organized and dense (Bennett, 2008). These birds are, therefore, more vulnerable to various bone-related conditions such as lameness, crooked toes, twisted legs, tibial dyschondroplasia, vertebral deformities, proximal femur osteoporosis, and femoral head necrosis, among others (Oviedo-Rondon et al., 2006). Subsequent to these bone-related conditions, the reduced ability of broilers to access feed and water, which can lead to reduced feed intake and dehydration, may culminate in reduced performance and increased mortality (Ben- nett, 2008). Kim et al. (2011) also pointed out that the stimulation of bone development and strength during the early growth period is an effective strategy to pre- vent leg and skeletal abnormalities in broilers. Although 1,25-dihydroxycholecalciferol is the most active metabolite of vitamin D 3 , the comparatively higher stability and lower toxicity of 25-hydroxylchole- calciferol [25(OH)D 3 ] makes it the more desirable sup- plement (Soares et al., 1995). Ward (1995) pointed out that the use of 25(OH)D 3 has been generally recognized as safe (GRAS) for inclusion in commercial broiler diets. As a preendocrine compound in avian species, 25(OH) D 3 is a metabolite of vitamin D, which is required for calcium mobilization, mineral regulation, and eggshell and bone mineralization. The supplementation of broil- er diets with 25(OH)D 3 has been reported to decrease feed consumption and to subsequently improve feed ef- Effects of the commercial in ovo injection of 25-hydroxycholecalciferol on broiler posthatch performance and carcass characteristics 1,2 A. Bello,* W. Zhai,* P. D. Gerard,† and E. D. Peebles* 3 *Department of Poultry Science, Mississippi State University, Mississippi State 39762; and †Department of Mathematical Sciences, Clemson University, Clemson, SC 29634 ABSTRACT In ovo injection of 25-hydroxycholecalcif- erol [25(OH)D 3 ] has been shown to improve hatchability of injected broiler eggs. Effects of the in ovo injection of commercial diluent containing various levels of 25(OH) D 3 on broiler posthatch performance and carcass char- acteristics were investigated in 2 trials. On each of 10 tray levels of a single-stage incubator, all treatment groups were randomly represented with each contain- ing 21 and 40 eggs in trials 1 and 2, respectively. Treat- ments included noninjected and diluent-injected (100 μL commercial diluent-injected) controls, and those that received 0.15, 0.30, 0.60, or 1.20 μg of 25(OH)D 3 in trial 1 and 0.20, 0.60, 1.80, or 5.4 μg of 25(OH)D 3 in trial 2, in 100 μL of commercial diluent using a com- mercial multi-egg injector on d 18 of incubation. On d 21 of incubation, chicks from each treatment replicate group were placed in corresponding floor pens. Feed intake, BW gain, and feed conversion were determined for the weekly and cumulative 0 to 21 d age intervals in trial 1 and for the weekly and cumulative 0 to 48 d age intervals in trial 2. In trial 2, 2 birds from each sex were selected from each treatment replicate group for determination of processing carcass characteristics on d 49 posthatch. Feed intake in the 0 to 7, 7 to 14, and 14 to 21 d age intervals and BW gain in the 0 to 7 and 14 to 21 d age intervals were affected by treatment in trial 2. The in ovo injection of up to 1.20 and 0.60 μg of 25(OH)D 3 in trials 1 and 2, respectively, did not affect the BW gain of birds during the 0 to 7, 7 to 14, and 14 to 21 d age intervals compared with the noninjected and diluent-injected control groups. It was concluded that the in ovo injection of up to 1.20 μg of 25(OH)D 3 into the amnion has no detrimental effect on the overall posthatch performance of broilers. Key words: 25-hydroxycholecalciferol, carcass, in ovo injection, performance, posthatch 2014 Poultry Science 93:155–162 http://dx.doi.org/10.3382/ps.2013-03389 PHYSIOLOGY, ENDOCRINOLOGY, AND REPRODUCTION 155 Received June 7, 2013. Accepted October 12, 2013. 1 This is journal article number J-12334 from the Mississippi Agri- cultural and Forestry Experiment Station supported by MIS-322270. 2 Use of trade names in this publication does not imply endorsement by Mississippi Agricultural and Forestry Experiment Station of these products, nor similar ones not mentioned. 3 Corresponding author: dpeebles@poultry.msstate.edu ©2014 Poultry Science Association Inc. Downloaded from https://academic.oup.com/ps/article-abstract/93/1/155/1537976 by guest on 29 July 2018