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Canyon, TX, United States

Cleale R.M.,Zoetis Ltd. | Amodie D.,Zoetis Ltd. | Bechtol D.T.,Agri Research Center Inc. | Drouillard J.S.,Kansas State University | And 7 more authors.
Journal of Animal Science

Trials were conducted with beef heifers at 4 sites to evaluate feedlot performance and carcass characteristics in response to implants containing 14 mg estradiol benzoate and 100 mg trenbolone acetate (EB/ TBA; Synovex Choice, Zoetis LLC, New York, NY), 14 mg estradiol benzoate (EB), 100 mg trenbolone acetate (TBA), or a sham-implanted control (SC). The study design at each site was a randomized complete block with 12 blocks and 4 treatments. Blocks of cattle at each site were harvested in commercial abattoirs when masked personnel estimated at least 60% of animals would yield carcasses with USDA quality grades of Choice or Prime. Data were pooled across sites for statistical analysis. Initial BW averaged 374 kg, and days on feed ranged from 98 to 126 d (mean 112 d). Heifers implanted with EB/TBA, EB, and TBA had greater ADG and G:F (P < 0.05) than SC; ADG and G:F were greater for EB/TBA than EB or TBA (P < 0.05). Heifers treated with TBA had greater G:F than EB (P < 0.05). Feed intake was not affected by treatments. Mean HCW and LM area for EB/TBA were greater than for other treatments (P < 0.05). Mean HCW for TBA was greater than SC (P < 0.05) but not different from EB. Mean LM area for EB and TBA were greater than SC (P < 0.05) but not different from each other. There were no treatment differences (P > 0.05) for KPH, 12th-rib fat thickness, or yield grade. Dressing percent was greater for EB/TBA than SC (P < 0.05) but not different from EB or TBA. Marbling score was decreased by EB/TBA (P < 0.05) compared with other treatments, but no other differences were noted. Despite the effect of EB/ TBA on marbling scores, there were no significant (P > 0.05) treatment differences on proportions of carcasses with quality grades ≥ Choice vs. < Choice. With respect to ADG and G:F, implants containing EB, TBA, or EB/TBA produced improved responses over SC. Furthermore, EB/ TBA induced greater ADG and G:F responses than EB and TBA. Results confirmed that EB and TBA have additive effects, as evidenced by the observation that calves implanted with EB/TBA had signifiantly greater ADG and G:F than heifers implanted with either EB or TBA alone or compared with SC heifers. © 2013 American Society of Animal Science. Source

Stromberg B.E.,University of Minnesota | Gasbarre L.C.,Gasbarre Consulting | Waite A.,Agri Research Center Inc. | Bechtol D.T.,Agri Research Center Inc. | And 4 more authors.
Veterinary Parasitology

Cooperia spp. have become the most prevalent parasites in United States cow/calf operations as observed in the USDA NAHMS (National Animal Health Monitoring System) Beef Cow/Calf survey in 2008. This is at least in part due to the widespread use of macrocyclic lactones that have recently been shown to have a reduced activity against these parasites. The effects of Cooperia spp. on cattle productivity are largely unknown. This study was conducted to assess their effect upon cattle housed under conditions found in American feedlots. Two hundred yearling calves (average weight 460lb/209kg) were acquired from northwestern Arkansas and northeastern Oklahoma and were vaccinated and dewormed upon arrival at the feedlot. Animals were comingled and preconditioned for approximately one month, and were fed a standard growing ration throughout the study. Calves were randomly divided into two groups (n=80, infected and control) and each group was further divided into two replicate pens (n=40). Calves from the two infected pens were orally inoculated with a gavage of 1×10 5 and 0.825×10 5 infective larvae of a recent isolate of Cooperia punctata on day 0 and 14, respectively, with the two control pens receiving a similar volume of tap water. Data collected included biweekly fecal egg counts, daily individual feed consumption and weight gain over the 60-day test period. The presence of C. punctata (>99% of recovered worms) was confirmed by necropsy and recovery from the small intestine on days 35 and 60 post infection (PI) in a subset of animals. Egg counts were positive by day 14 PI and remained at numbers similar to values seen in field studies. The control group gained weight 7.5% more rapidly (p=0.02) than infected animals (3.24lb/1.47kg per day vs. 3.0lb/1.36kg per day, respectively). The Cooperia-infected calves also consumed 1.5lb (0.68kg) less dry feed per day than the control animals (p=0.02). These data suggest that C. punctata has a deleterious effect on both appetite and nutrient uptake or utilization. At necropsy (days 35 and 60), the draining mesenteric lymph nodes of infected animals were increased in size and the small intestinal mucosa was thickened and covered with a thick layer of mucus in the infected animals. The most prominent histological changes in the Cooperia- infected animals included a moderate increase in the number of intraepithelial lymphocytes and globule leukocytes, as well as aggregates of eosinophils within the lower lamina propria. The only significant difference was an increase in the goblet cell density at day 60. Anthelmintic sensitivity/resistance of the Cooperia isolate used was determined by treatment of one pen of infected calves with a macrocyclic lactone and the other pen with a benzimidazole at the completion of the study. The macrocyclic lactone treatment (n=40) did not remove the parasites (FECRT=8.8%), while treatment with a benzimidazole was very effective (FECRT=98.1%). This study demonstrated that C. punctata has a significant effect on cattle productivity, both reduced weight gain and decreased feed intake compared to controls. © 2011 Elsevier B.V. Source

Cleale R.M.,Pfizer | Bechtol D.T.,Agri Research Center Inc. | Drouillard J.S.,Kansas State University | Edmonds J.D.,Johnson Research | And 6 more authors.
Journal of Animal Science

Synovex Plus (SP) is a product that delivers 28 mg of estradiol benzoate (EB) and 200 mg of trenbolone acetate (TBA). We studied the impact of a polymeric, porous coating on SP implants (CSP) to prolong release of EB and TBA, and stimulate feedlot performance of feedlot cattle for an extended period. In an explant study, 30 steers were implanted with SP in one ear and CSP in the contralateral ear. Cattle (n = 6/d) were necropsied 40, 81, 120, 160, and 200 d after treatment, and remaining EB and TBA were quantified. Linear regression of EB and TBA remaining as a function of time for each treatment were computed. Rates of EB and TBA depletion from SP were -0.1980 (r2 = 0.9994) and -1.7073 mg/d (r2 = 0.9644), respectively, and for CSP rates of EB and TBA depletion were -0.1049 (r2 = 0.9123) and -0.9466 mg/d (r2 = 0.9297), respectively. The effect of treatment on depletion rates of each analyte were significant (P < 0.05). Data also showed EB and TBA were delivered from CSP at least 200 d but were delivered from SP about 120 d. Multisite trials with beef-type steers (4 sites) and heifers (4 sites) evaluated feedlot performance and carcass characteristics in response to a CSP implant or when sham implanted (SC). A randomized complete block design with 9 blocks and 2 treatments was used per site within animal gender. Across sites, steers (n = 342, BW = 297 kg) were fed finishing rations for 190 to 202 d (mean 198 d) and heifers (n = 342, BW = 289 kg) were fed finishing rations for 191 to 201 d (mean 198 d). Cattle were harvested and carcasses evaluated. Data were pooled across sites within gender for statistical analysis. Steers and heifers treated with CSP yielded greater (P ≤ 0.003) ADG, DMI, and G:F than SC steers and heifers. Mean BW differences between CSP and SC continued to increase throughout the study, indicating CSP stimulated growth of steers and heifers for 198 d. Mean carcass weights of CSP steers (P = 0.005) and heifers (P = 0.004) were greater than those of SP steers and heifers by 26.2 and 20.6 kg, respectively. The LM area was larger (P < 0.001) in CSP steers and heifers than SC cattle. Marbling decreased with CSP treatment (P ≤ 0.031), which caused reductions (P ≤ 0.006) in proportions of carcasses grading Prime or Choice. Evidence from these studies showed that a single administration of CSP increased feedlot cattle performance for at least 198 d, compared with SC, and may reduce the need to reimplant cattle. © 2012 American Society of Animal Science. All rights reserved. Source

McLaughlin C.L.,Pfizer | Bechtol D.T.,Agri Research Center Inc. | Lawrence T.E.,West Texas A&M University | Lechtenberg K.,Midwest Veterinary Services | And 4 more authors.
Professional Animal Scientist

Two studies were conducted with beef steers to compare the effects of long-acting implants Synovex One (SYN-ONE) and Revalor-XS with each other and with the shorter-acting implant Synovex Plus (SYN-PLUS) on growth performance and carcass quality. Steers (n = 240, initial BW = 384 ± 4.0 kg) in Nebraska were administered SYN-ONE, SYN-PLUS, or Revalor-XS 161 d before slaughter. Steers (n = 300, initial BW = 262 ± 3.6 kg) in Texas were administered the same implants 200 d before slaughter. Each experiment was conducted according to a randomized complete block design with 10 blocks of 3 treatments and pen as the experimental unit. Blocking was based on pretreatment BW, and treatments within a block were assigned to contiguous pens. On d 0, steers were weighed and received assigned implants. Steers were fed finishing diets and were weighed twice more during each experiment and on 2 consecutive days before slaughter in commercial facilities for carcass evaluation. Statistical-analysis models included the fixed effect of treatment and random effects of block and block by treatment interaction and residual; BW and ADG were analyzed as repeated measures. Overall growth performance did not differ (P > 0.05) among implant groups in either location. However, there were differences (P < 0.05) in BW, ADG, and G:F between treatments during some intermediate intervals, i.e., SYN-PLUS was greater than SYN-ONE during the first interval and SYN-ONE was greater than SYN-PLUS during some of the later intervals. Carcass characteristics did not differ (P > 0.05) among implant groups. It was concluded that the 3 implants were equally efficacious. © 2013 American Registry of Professional Animal Scientists. Source

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