A 3-yr study utilized 300 Angus-based, spring-born heifers to evaluate postweaning heifer development systems on gain, reproductive performance, and feed efficiency as a pregnant heifer. Heifers were blocked by BW and randomly assigned to graze corn residue (CR), upland range (RANGE), or were fed 1 of 2 diets in a drylot differing in energy levels: high (DLHI) or low (DLLO). Heifers developed on DLHI and DLLO were managed within the drylot for 166 d in yr 1, 150 d in yr 2, and 162 d in yr 3. Heifers developed on RANGE grazed winter range for an equivalent amount of days each yr as the DLHI and DLLO heifers. Heifers assigned to CR grazed for 103 d in yr 1, 84 d in yr 2, and 97 d in yr 3 before being transported to graze winter range for the remainder of the treatment period. All heifers were managed as a single group following the treatment period. Artificial insemination and natural mating were utilized during breeding. Percent of mature BW prior to the breeding season was greater ( = 0.02) for DLHI (67%) compared with RANGE (59%) and CR (58%). Pregnancy rates to AI were not different ( = 0.51) among treatments (59 ± 6%), and final pregnancy rates were also not different (87 ± 4%, = 0.54). A subset of AI-pregnant heifers from each treatment were placed in a Calan gate feeding system. Heifers were allowed a 20-d acclimation period before beginning the 90 d trial at approximately 170 d in gestation. Heifers were offered ad libitum hay; amount offered was recorded daily and orts collected weekly. Initial BW was not different ( = 0.58) among treatments (459 ± 11 kg). Body weight at the end of the trial (497 ± 17 kg) was also not different ( = 0.41). Intake was not different ( = 0.33), either as DMI (10.00 ± 1.07 kg) or residual feed intake (0.018 ± 0.190). There was no difference in ADG ( = 0.36, 0.42 ± 0.23 kg/d) among treatments. Although the total development cost was not different among treatments ( = 0.99), there was a $41 difference ( < 0.01) between the mean of the most expensive diet (DLHI) and the mean of the two least expensive diets (CR and RANGE). Developing heifers to a greater prebreeding BW did not influence subsequent AI or overall pregnancy rates or feed efficiency as a pregnant heifer.

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greater than 50% of the rub-off coating had been removed from the Estrotect patch and were AI 12 h later. Following the AI period, mature bulls were then placed with heifers at ratios of 1:49 and 1:35 at L2 and L3, respectively, for 19 d to conclude a 25 d breeding season.Heifers were managed on native Sandhills range throughout the summer grazing period. Pregnancy diagnosis was conducted via transrectal palpation approximately 45 d following bull removal and ending BW measured. Non-pregnant heifers were marketed as stocker cattle. During the second production year, heifers (n = 1,667; 706 and 961, for IMP and CON, respectively) retained as replacements were managed in 3 groups and grazed native upland range throughout the year without further treatment. Economic EvaluationWinter grazing cost was estimated to be one-half the grazing costs for a mature cow ($0.46/d) based on heifer BW at weaning. Winter range with supplement was valued at $0.75/d. Summer grazing costs were $0.55/d for upland grass. Additional development costs, including feed delivery costs, breeding costs, and health and veterinarian costs, were charged at $0.36/ head/d. Average heifer purchase and cull prices were based on USDA Agricultural Marketing Service prices reported in Nebraska for each date. Th e total value of cull heifers was subtracted from the total cost of all developed heifers. Total costs were then divided by the number of heifers exposed to determine the total cost of 1 pregnant heifer. Th is value was divided by fi nal pregnancy rate to determine the total net cost of 1 pregnant heifer.to the label, which in general is from 30 to 45 d of age and prior to weaning. Since traditional heifer development programs focus on maximizing reproductive rates, reproductive risk associated with implants not intended for breeding females has been avoided.Th e objective of the present study was to evaluate eff ects of a single stocker implant (Revalor G) on growth and reproductive performance of yearling beef heifers in the Nebraska Sandhills. ProcedureIn 2011, 12 mo old crossbred beef heifers (n = 3,242; 525 ± 4 lb) grazing native Sandhills range at 3 locations were randomly assigned to be implanted with Revalor G (40 mg trenbolone acetate and 8 mg estradiol, IMP) or not implanted (control, CON). Heifers were implanted at the beginning of the grazing period (May 1). At the time of implant, all heifers were vaccinated (Pyramid 5, Boehringer Ingelheim, St. Joseph, MO; and VL5 Staybred, Zoetis, Florham Park, NJ) and treated with a topical endectocide (Ivermax, RXV Products, Westlake, TX). At each location, heifers grazed common upland pastures for 164 ± 4 d.Breeding season began 82 ± 2 d following trial initiation. Heifers at location 1 (L1, n = 942) were synchronized with 2 prostaglandin F 2α (PG) injections administered 17 d apart (5 ml, Lutalyse, Zoetis, Florham Park, NJ) followed by 5 d of estrus detection and AI. Mature bulls were then placed with heifers at a 1:52 bull to heifer ratio for 20 d to conclude the breeding season. At location...