Impacts of economic factors influencing net returns of beef feedlot heifers administered two implant programs and fed for differing days-on-feed from pooled randomized controlled trials.

The objective of this research was to evaluate the effects of two implant programs and differing days-on-feed (DOF) on net returns of beef feedlot heifers using sensitivity analyses of key economic factors. Crossbred beef heifers [ = 10,583; initial weight 315 kg (± 20.1 SD)] were enrolled across three trials (one Kansas, two Texas feedlot trials).

Mineral composition of serially slaughtered Holstein steers supplemented with zilpaterol hydrochloride.

Calf-fed Holstein steers (n = 115; 449 ± 20 kg) were utilized in a serial harvest experiment. A baseline group of five steers was harvested after 226 d on feed (DOF), which was designated day 0. The remaining cattle were assigned randomly to 11 harvest groups, with slaughter every 28 d.

A randomized trial and multisite pooled trial analyses comparing effects of two hormonal implant programs and differing days-on-feed on carcass characteristics and feedlot performance of beef heifers.

Research objectives were to evaluate effects of two implant programs for beef heifers fed three 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 two 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.

Comparison of a traditional bovine respiratory disease control regimen with a targeted program based upon individualized risk predictions generated by the Whisper On Arrival technology.

The study objective was to determine if cattle health and performance comparing a targeted bovine respiratory disease (BRD) control program based on individualized risk prediction generated by a novel technology (Whisper On Arrival) was superior to a negative control (no metaphylaxis) yet no different than a positive control (conventional BRD control; 100% application). Across four study sites, auction market-derived beef calves were randomly allocated to one of four BRD control treatment groups: 1) Negative control (Saline), 2) Positive control (Tildipirosin [TIL] to 100% of the group), 3) Whisper-high (±TIL based on conservative algorithm threshold), and 4) Whisper-low (±TIL based on aggressive algorithm threshold). Within either Whisper On Arrival group, only calves predicted to be above the algorithm threshold by the technology (determined a priori) were administered TIL leaving the remainder untreated.

Innate and acquired immune responses of colostrum-fed neonatal Holstein calves following intranasal vaccination with two commercially available modified-live virus vaccines.

Objective: To compare immune responses induced by 2 commercially available vaccines with a bovine herpesvirus type 1 (BHV1) component following intranasal (IN) administration to colostrum-fed calves.

Animals: 90 male Holstein calves (ages, 5 to 14 days).

Procedures: In a randomized complete block design, each calf received 2 mL (1 mL/nostril) of vaccine A (n = 30), vaccine B (30), or saline (0.

A pooled analysis of six large-pen feedlot studies: effects of a noncoated initial and terminal implant compared with a single initial and delayed-release implant on arrival in feedlot heifers.

Randomized complete block design experiments ( = 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 (E) initial implant (Revalor-IH) and reimplanted with 200 mg TBA and 20 mg E (Revalor-200; REPEATED) to a single 80 mg TBA and 8 mg E uncoated; 120 mg TBA and 12 mg E 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 body weight = 333 kg SEM (4.

Effects of a single initial and delayed release implant on arrival compared with a non-coated initial implant and a non-coated terminal implant in heifers fed across various days on feed.

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 ( = 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 (E) administered on arrival (SINGLE), or 80 mg TBA and 8 mg E administered on arrival followed by 200 mg TBA and 20 mg E after approximately 90 d (REPEATED) and 2) duration of DOF: harvested after approximately 172, 193, and 214.

Zilpaterol hydrochloride lowers marbling score by dilution of marbling and depression of intramuscular adipocyte volume in M. longissimus dorsi of beef steers.

We hypothesized that zilpaterol hydrochloride (ZH) depresses marbling scores in beef cattle by dilution of the intramuscular (i.m.) adipose tissue in the longissimus thoracis (LT) by increased muscle cross-sectional area.

Acute immunologic and metabolic responses of beef heifers following topical administration of flunixin meglumine at various times relative to bovine herpesvirus 1 and challenges.

Objective: To quantify acute immunologic and metabolic responses of beef heifers following topical administration of transdermal flunixin meglumine (TDFM) at various times relative to bovine herpesvirus 1 (BHV1) and challenges.

Animals: 32 beef heifers (mean body weight, 170 kg).

Procedures: Heifers were assigned to 1 of 4 groups.

Carcass fabrication yields of beef steers supplemented zilpaterol hydrochloride and offered ad libitum or maintenance energy intake.

An experiment was conducted to evaluate the fabrication yields of carcasses from beef steers supplemented zilpaterol hydrochloride (ZH) and fed at maintenance (MA) or ad libitum (AB) intake levels. Beef steers (n = 56) from a common sire were blocked (n = 28 per block) by terminal growth implant and sorted into pairs by BW. Four pairs (n = 8) were harvested on day 0; the remaining 24 pairs (n = 48) were assigned to a dietary intake level (MA or AB) and days on feed (28 or 56 d).

The effect of zilpaterol hydrochloride on beef producer and processor revenue of calf-fed Holstein steers.

A serial harvest was conducted every 28 d from 254 to 534 days on feed (DOF) to quantify changes in growth and composition of calf-fed Holstein steers (n = 110, initial BW = 449.2 ± 19.9 kg).

Live growth performance, carcass grading characteristics, and harvest yields of beef steers supplemented zilpaterol hydrochloride and offered ad libitum or maintenance energy intake.

A trial was conducted to examine live growth efficiency, harvest yields, and carcass grading performance of steers fed at maintenance (M) or at ad libitum (A) level of intake during zilpaterol hydrochloride (Z) supplementation. Single-sired, beef steers (n = 56; start of trial BW 590 ± 36 kg) blocked (n = 2) by weight and terminal implant were sorted into pairs (n = 14 per block) by weight. Pairs of steers were initially assigned to 0, 28, or 56 d of feeding.

Evaluation of coated steroidal implants containing trenbolone acetate and estradiol-17β on live performance, carcass traits, and sera metabolites in finishing steers.

Crossbred beef steers (n = 240; 12 pens/treatment; initial BW = 305 ± 17.7 kg) were used in a randomized block design feedlot study to evaluate the influence of coated trenbolone acetate (TBA) and estradiol-17β (E2) implants (Merck Animal Health, Madison, NJ) on gain performance, carcass traits, and sera metabolites. The five treatments were no implant (NI), Revalor-XR on d 0 [200 mg TBA + 20 mg E2 (coated); XR], Revalor-XS on d 0 [200 mg TBA + 40 mg E2 (total): 80 mg TBA + 16 mg E2 (noncoated) and 120 mg TBA + 24 mg E2 (coated); XS], Revalor-200 on d 0 [200 mg TBA + 20 mg E2 (noncoated); E200], or Revalor-200 on d 70 (D200).

Influence of beta-agonists (ractopamine HCl and zilpaterol HCl) on fecal shedding of Escherichia coli O157:H7 in feedlot cattle.

Ractopamine HCl and zilpaterol HCl, beta-agonists recently approved for use in feedlot cattle to improve performance traits and carcass leanness, were examined for their effects on fecal shedding of Escherichia coli O157:H7 in feedlot cattle. Fecal samples (n = 2,454) were obtained from four experiments (one ractopamine HCl, three zilpaterol HCl) over the course of a 3-year period, either by rectal palpation (ractopamine HCl experiment) or from pen-floor fecal pats. Samples were cultured quantitatively and qualitatively for E.

Comparison of single vaccination versus revaccination with a modified-live virus vaccine containing bovine herpesvirus-1, bovine viral diarrhea virus (types 1a and 2a), parainfluenza type 3 virus, and bovine respiratory syncytial virus in the prevention of bovine respiratory disease in cattle.

Objective-To compare effects of administration of a modified-live respiratory virus vaccine once with administration of the same vaccine twice on the health and performance of cattle. Design-Randomized, controlled trial. Animals-612 mixed-breed male cattle with unknown health histories.