Two experiments evaluated the effect of implant number, type, and total steroidal dose on live animal performance and carcass traits in heifers fed for three different days on feed (DOF). In experiment 1, heifers (n = 3,780; 70 heifers/pen and 9 pens/treatment; initial body weight [BW] = 309 kg) were used in a 2 × 3 factorial arrangement of treatments. Factors were as follows: 1) implant (all from Merck Animal Health, De Soto, KS): 200 mg trenbolone acetate (TBA) and 20 mg estradiol-17β (E2) administered on arrival (SINGLE), or 80 mg TBA and 8 mg E2 administered on arrival followed by 200 mg TBA and 20 mg E2 after approximately 90 d (REPEATED) and 2) duration of DOF: harvested after approximately 172, 193, and 214. In experiment 2, heifers (n = 3,719; 65 to 70 heifers/pen and 9 pens/treatment; initial BW = 337 kg) were used with the same factors as experiment 1, except DOF were 150, 171, and 192. No implant × DOF interaction (P ≥ 0.06) was noted for any performance parameters in either experiment. Heifers administered REPEATED had improved (P ≤ 0.05) live gain to feed ratio (G:F) and carcass-adjusted G:F and tended (P = 0.09) to have greater hot carcass weight (HCW) in experiment 1. Increasing DOF resulted in greater (P ≤ 0.01) live and carcass-adjusted final BW and decreased (P = 0.01) live ADG in experiment 1. As DOF increased, HCW, HCW gain, and dressing% (P ≤ 0.01) increased in experiment 1. The mean carcass transfer was 79.6% across the 42 d terminal window in experiment 1. In experiment 2, REPEATED had improved (P = 0.03) carcass-adjusted G:F compared with SINGLE, but HCW was not different (P = 0.36) between treatments. Increased DOF resulted in greater (P ≤ 0.01) final live and carcass-adjusted BW, decreased (P ≤ 0.01) live and carcass-adjusted ADG, and poorer (P ≤ 0.01) live and carcass-adjusted G:F in experiment 2. In experiment 2, dressing percentage was greater (P = 0.02) in REPEATED compared with SINGLE. Heifers given SINGLE had greater (P = 0.01) back fat and estimated empty body fat (EBF), whereas REPEATED had fewer (P = 0.01) Yield Grade 4 carcasses and greater (P = 0.01) longissimus muscle (LM) area. Increased DOF resulted in greater (P ≤ 0.04) HCW, HCW gain, dressing%, back fat, LM area, marbling, EBF%, and United States Department of Agriculture (USDA) Prime-grading carcasses, Yield Grade 4 and 5, and over 454-kg carcasses in experiment 2. Carcass ADG and carcass transfer indicate a 0.70 kg carcass ADG between 150 and 192 DOF, resulting in an average carcass transfer of 72.2% in experiment 2. Although feedlot growth performance and HCW did not differ between the implant regimens tested, increasing DOF resulted in decreased live growth performance while increasing the proportion of USDA prime carcasses and HCW.

Research objectives were to evaluate effects of 2 implant programs for beef heifers fed 3 different durations (days-on-feed; DOF) on carcass weight and composition (primary outcomes) and feedlot performance (secondary outcomes) at commercial feedlots. Data from a randomized trial in Kansas were analyzed separately and also pooled with data from 2 previously published trials conducted in Texas. Heifers were randomly allocated to pens within a block, and pens were randomized to treatments in a 2 × 3 factorial randomized complete block design. Implant programs were IH + 200 – an initial Revalor-IH implant [80 mg trenbolone acetate (TBA) and 8 mg estradiol (E2)] and a re-implant after a mean of 98-d (± 10.8 SD) with Revalor-200 (200 mg TBA and 20 mg E2), or XH – Revalor-XH, a single extended-release implant (200 mg TBA and 20 mg E2). Heifers were fed to a baseline endpoint (BASE; pooled mean 166-d ± 11.9 SD), +21, or +42 additional DOF. A total of 10,583 crossbred heifers with mean initial body weight (BW) 315 kg (± 20.1 SD) were enrolled in 144 pens in 24 blocks (treatment replications) across the 3 trials. General and generalized linear mixed models accounting for clustering of trials, blocks, and pens were used to test for effects of treatments, with significance set at α = 0.05. The only implant program × DOF interaction in pooled analyses was for dry matter intake (DMI; P < 0.01); IH + 200 heifers had lower mean DMI than XH when fed +42 DOF. Gain:feed was higher for IH + 200 compared to XH with dead and removed animals excluded (P < 0.01) or included (P = 0.03). For IH + 200, hot carcass weight (HCW) increased (P < 0.01), USDA Yield Grade (YG) distributions shifted towards lower numerical categories (P < 0.01), and Prime carcasses decreased while Select increased compared to XH (P < 0.01). For each incremental increase in DOF, final BW (P < 0.01) and HCW increased (P < 0.01), while daily gain (P < 0.01) and gain:feed (P < 0.01) decreased. Categories of YG were affected by DOF (P < 0.01); there were fewer YG 1 and 2 and more YG 4 and 5 carcasses for +42 compared to BASE and +21. USDA Quality Grade (QG) distributions differed by DOF (P < 0.01); each incremental increase in DOF resulted in more Prime and fewer Select carcasses. Without meaningful interactions, tested implant programs likely have a consistent effect when heifers are fed to similar DOF, while changes in HCW, QG, and YG may influence marketing decisions when extending DOF.

The objectives of this study were to examine the growth, DMI, and feeding behaviors of Angus and Hereford bulls; identify the relationships between feeding behaviors and variation in DMI and residual feed intake (RFI); and determine the value of feeding behaviors in predicting DMI. Individual DMI was measured in Angus bulls (n=189; initial BW=427±3.4 kg) and Hereford bulls (n=146; initial BW=411±4.1 kg) fed a grower ration for 71 d in 2009, 78 d in 2010, and 74 d in 2011 using a GrowSafe intake monitoring system. Feeding frequency (FF, meals/d), head down duration (HDD, s/d), head down duration per meal (HDDM, HDD/FF, s/meal), average meal size [AMS, kg/(meal·d)], and feeding rate (FR, g/s) were also measured or calculated using behavior data collected by the GrowSafe system. Ultrasound measures of 12th-rib fat thickness (UFT), longissimus muscle area (ULMA), and intramuscular fat (IMF) were determined during the midtest-weight event of every trial. The data from 3 yr were pooled to generate mean differences between the breeds. Residual feed intake was calculated using a linear regression of DMI on ADG and midtest BW0.75 (MMWT). Animals were classified into 3 RFI groups based on their RFI score as Low (>0.5 SD below the mean), Average (±0.5 SD from the mean), or High RFI (>0.5 SD above the mean). Angus bulls in the Low RFI group consumed 17% (P<0.0001) less DM than the bulls in the High RFI group, while in the Hereford bulls there was a 14% (P<0.0001) difference in DMI between Low and High RFI groups. Significant phenotypic correlations were observed between RFI and DMI (0.83, 0.77), G:F (-0.65, -0.51), HDD (0.41, 0.59), HDDM (0.40, 0.53), AMS (0.52, 0.36), and FR (-0.31, -0.51) in Angus and Hereford bulls, respectively. The HDD, HDDM, and FR were significantly correlated with DMI. The feeding behavior traits, HDD, HDDM, and FR when added to the RFI base model, explained 18, 17, and 13%, respectively, of the variation in DMI not explained by ADG and MMWT in Angus bulls. Similarly, in Hereford bulls, HDD, HDDM, and FR explained 35, 26, and 24%, respectively, of the variation in DMI not explained by ADG and MMWT. These data suggest that feeding behaviors are related to DMI of growing Angus and Hereford bulls.

Objectives were to evaluate the effects of temperament at feedlot arrival and breed type on productivity, feed efficiency, feeding behavior, and carcass quality traits in finishing beef heifers, and to examine interactions between temperament and breed type. Heifers (Angus, Braford, Brangus, and Simbrah, N = 411, BW = 280 kg) were fed a high-grain diet (ME = 3.0 Mcal/kg DM) in pens equipped with electronic feed bunks. Quality grade (QG), yield grade (YG), and Warner-Bratzler shear (WBS) force values (day

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Abstract Randomized complete block design experiments (n = 6 experiments) evaluating steroidal implants (all from Merck Animal Health, Madison, NJ) were conducted in large-pen feedlot research facilities between 2015 and 2018 comparing an 80 mg trenbolone acetate (TBA) and 8 mg estradiol-17β (E2) initial implant (Revalor-IH) and re-implanted with 200 mg TBA and 20 mg E2 (Revalor-200; REPEATED) to a single 80 mg TBA and 8 mg E2 uncoated; 120 mg TBA and 12 mg E2 coated implant (Revalor-XH) at arrival (SINGLE) on growth and carcass responses in finishing heifers. Experiments occurred in Nebraska, Oklahoma, Washington, and Texas. Similar arrival processing was used across experiments where 17,675 heifers [initial BW = 333 kg SEM (4.1)] were enrolled into 180 pens (90 pens/treatment with 65 to 240 heifers/pen) and fed for 145 to 222 d. Only REPEATED heifers were removed from their pen at re-implant. Diets contained monensin and tylosin, consisted of ingredients common to each region, and contained greater than 90% concentrate. Ractopamine hydrochloride was fed for a minimum of 28 d prior to harvest. Linear mixed-models were used for all analyses; model-adjusted means for each implant group and the corresponding SEM were generated. Distributions of USDA quality (QG) and yield grade (YG) were analyzed as ordinal outcomes. No differences (P ≥ 0.11) were detected for any performance parameters except DMI, where SINGLE had greater (P = 0.02) DMI (9.48 vs. 9.38 ± 0.127 kg) compared with REPEATED. Heifers implanted with REPEATED had greater (P ≤ 0.02) HCW (384 vs. 382 ± 2.8 kg), dressing percentage (64.54 vs. 64.22 ± 0.120%), and ribeye area (91.87 vs. 89.55 ± 0.839 cm2), but less (P ≤ 0.01) rib fat (1.78 vs. 1.83 ± 0.025 cm) and calculated YG (2.82 vs. 2.97 ± 0.040), and similar (P = 0.74) marbling scores (503 vs. 505 ± 5.2) compared with SINGLE heifers. Distributions of USDA YG and QG were impacted (P ≤ 0.03) by treatment such that, REPEATED had fewer USDA Prime and YG 4 and 5 carcasses. Heifer growth performance did not differ between implant regimens, but HCW and muscling did; perhaps indicating that REPEATED may be suited for grid-based marketing, and SINGLE might be suited for heifers sold on a live basis depending upon market conditions and value-based grid premiums and discounts. However, these decisions are operational dependent, and also may be influenced by factors including animal and employee safety, stress on animals, processing facilities, time of year, labor availability, and marketing strategies.

the value of using CUSUM procedures to monitor feeding behavior patterns to more accurately detect BRD prior to clinical symptoms in feedlot cattle.

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