Beef Research News
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Nebraskas initiates Tritrichomonas Import Regulations
In January 2008, the state of Nebraska enacted requirements that all bulls (non-virgin or over 24 months of age) are required to be test negative for Tritrichomonas prior to entering the state. The bulls must have three consecutive negative trichomoniasis culture tests at least one week apart or one negative PCR test within 30 days prior to importation and samples must be collected by an accredited veterinarian and conducted by a laboratory accredited by the AAVLD and the bull must not be used for breeding purposes between the tests and the time the bull(s) is imported into Nebraska. The certificate of veterinary inspection must contain information regarding the Trichomoniasis status of the bull(s). For more specific regulations and exceptions to the testing requirements please review the full order at http://www.agr.ne.gov/division/bai/trich_order_4.pdf
Heat Stress effect on follicular growth
The objective was to determine whether exposure of Gir (Bos indicus) cows to heat-stress (HS) causes immediate and delayed deleterious effect on follicular dynamics, hormonal profile and oocyte competence. The cows were kept in tie-stalls for an adaptive thermoneutral period of 28 days (Phase I, Days −28 to −1). In Phase II (Days 0–28) cows were randomly allocated into control (CG, n=5) and HS (HS, n=5) treatments. The HS cows were placed in an environmental chamber at 38°C and 80% relative humidity (RH) during the day and 30°C, 80% RH during the night for 28 days. The CG group was maintained in shaded tie-stalls (ambient temperature) for 28 days. During Phase III (Days 28–147) animals were placed in tie-stalls (Days 28–42) followed by pasture (Days 42–147) under thermoneutrality. In each phase, weekly ovum pick up (OPU) sessions were to evaluate follicular development, morphology of cumulus–oocyte complexes (COCs), and developmental competence after in vitro maturation, fertilization, and culture. Serum concentrations of progesterone (P4) and cortisol were evaluated by radioimmunoassay. Exposure of Gir cows to HS had no immediate effect on reproductive function, but exerted a delayed deleterious effect on ovarian follicular growth, hormone concentrations, and oocyte competence. Heat-stress increased the diameter of the first and second largest follicles from Days 28 to 49. Indeed, HS increased the number of >9mm follicles (characterized as follicular codominance) during this phase. Cows exposed to HS had longer periods of non-cyclic activity (P4<1ng/mL), as well as shorter estrous cycles. However, HS did not affect cortisol concentration as compared to CG. Although HS had no significant effect on cleavage rate, it reduced blastocyst development during Phase III. In conclusion, long-term exposure of B. indicus cattle to HS had a delayed deleterious effect on ovarian follicular dynamics and oocyte competence.
de S. Torres-Júnior, J. R., M. de F.A. Pires, W.F. de Sá, A. de M. Ferreira, J.H.M. Viana, L.S.A. Camargo, A.A. Ramos, I.M. Folhadella, J. Polisseni, C. de Freitas, C.A.A. Clemente, M.F. de Sá Filho, F.F. Paula-Lopes, P.S. Baruselli. Effect of maternal heat-stress on follicular growth and oocyte competence in Bos indicus cattle Theriogenology Volume 69, Issue 2, Pages 155-166 (15 January 2008)
Prevalence of Tritrichomonas in AL Beef Bulls
The objective of this study was to estimate the prevalence of Tritrichomonas foetus infections in Alabama (USA) beef bulls through prospective and retrospective surveys. The prospective survey included 240 Alabama beef bulls that were sampled between January 2005 and March 2006. Preputial smegma was collected from the 240 bulls with a dry pipette and cultured in an InPouch™ TF T. foetus culture pouch (BioMed Diagnostics; White City, OR, USA). The samples were evaluated microscopically once a day for 6 days for growth resembling T. foetus. To avoid false-positives due to fecal trichomonads, all suspect cultures were sent to both the Alabama Department of Agriculture Veterinary Diagnostic Laboratory in Auburn, AL, USA and the Auburn University College of Veterinary Medicine Parasitology Laboratory (Auburn, AL, USA) for polymerase chain reaction (PCR) confirmatory assays. Of the 240 bulls cultured in the prospective survey, 3 (1.25%) cultures were considered suspect on microscopic evaluation. However, PCR-based assays were negative for T. foetus, suggesting that the samples most likely contained fecal trichomonads. The retrospective analysis included 374 T. foetus cultures performed at the Alabama Department of Agriculture Veterinary Diagnostic Laboratory between October 2002 and March 2005. Of the 374 bulls included in the retrospective analysis, only 1 (0.27%) was confirmed positive by a PCR-based assay.
Rodninga,S.P., D.F. Wolfe, R.L. Carson, J.C. Wright, H.D. Stockdale, M.E. Pacoli, H.C. Busby, S.E. Rowe. Prevalence of Tritrichomonas foetus in several subpopulations of Alabama beef bulls. Theriogenology. 2008 Vol 69, Issue 2: 212-217.
MLV vaccine timing effect on newly-received calves
Stress commonly associated with weaning, marketing, and shipment of feeder cattle can temporarily compromise immune function; thereby, reducing the effective response to vaccination intended to control bovine respiratory disease (BRD). Two vaccination timing treatments were used to evaluate the effect of timing of a multivalent modified live virus (MLV) BRD vaccine on health, performance, and infectious bovine rhinotracheitis (IBR) antibody titers of newly-received stocker cattle. Crossbred bull and steer calves (n = 528) were weighed (197 ± 2.4 kg) and randomly assigned to MLV vaccination treatment: 1) MLV vaccination upon arrival (AMLV), or 2) delayed (14 d) MLV vaccination (DMLV). All cattle were processed similarly according to routine procedures with the exception of initial MLV vaccination timing. Subsequently, BW were recorded on d 14, 28, and 42. Blood samples were collected on d 0, 14, 28, and 42 to determine serum IBR titers, comparisons were made between treatments on a receiving-day basis and an equivalent post-vaccination day basis. Daily BW gains were greater (P 0.05) for DMLV calves from d 0 to 14 (0.88 vs. 1.16 ± 0.22 kg/d) and from d 0 to 42 (0.65 vs. 0.75 ± 0.09 kg/d). Days to first treatment, total treatment cost, percentage death loss, and pasture ADG after the 42-d receiving period did not differ (P 0.15). Morbidity rates for BRD were high for both AMLV and DMLV (71.5 and 63.5%, respectively) and did not differ (P = 0.12). Positive IBR titer seroconversion were greater (P 0.03) for DMLV calves on d 42 of the study, and 28 d and 42 d equivalent post-vaccination basis. Delaying vaccination 14 d may increase ADG during the receiving period compared to vaccinating upon arrival; and seroconversion to IBR was greater in DMLV calves, indicating a possible improvement in acquired immune response when MLV vaccination is delayed.
Richeson, J. T. , P. A. Beck, M. S. Gadberry, S. A. Gunter, T. W. Hess, D. S. Hubbell III, C. Jones Effects of on-arrival versus delayed modified-live virus vaccination on health, performance, and serum infectious bovine rhinotracheitis titers of newly-received beef calves J. Anim Sci., doi: 10.2527/jas.2007-0593 Published online first on January 11, 2008
Distillers byproducts in beef feeding industry
The ethanol industry is expanding rapidly. This expansion in production of renewable energy also increases production of byproducts. These byproducts, primarily distillers grains plus solubles (DGS), are utilized very efficiently by ruminants. When the starch in corn is fermented to produce ethanol, the remaining nutrients (protein, fat, fiber) are concentrated about 3 fold. While DGS is an excellent protein source for ruminants, the large supply and the price relative to corn make DGS an attractive energy source as well. This is especially important with reduced availability and higher price of corn because of demand by the ethanol industry. A meta-analysis of 9 experiments, where various levels of wet DGS were fed to feedlot cattle, shows that wet DGS produced higher ADG and G:F compared to cattle fed corn-based diets without DGS. A similar analysis with dry DGS showed similar type of responses but with less apparent feeding value for dry DGS compared to wet DGS. Metabolism studies suggest the fat in DGS may be partially protected from ruminal degradation leading to greater proportion of unsaturated fatty acids at the duodenum and greater total tract fat digestibility. Both the fat and the undegradable protein in DGS appear to explain some but not all of the greater feeding value of DGS compared to corn. Lower quality roughages may be used in feedlot diets containing wet DGS because of the protein, moisture, and physical characteristics the DGS contains. The feeding value of DGS is greater than dry rolled corn or high moisture corn; however, the feeding value of DGS appears to be less when fed in finishing diets based on steam-flaked corn than in those based on dry-rolled or high-moisture corn.
Klopfenstein, T.J., G. E. Erickson, V. R. Bremer. BOARD-INVITED REVIEW: Use of distillers byproducts in the beef cattle feeding industry J. Anim Sci., doi: 10.2527/jas.2007-0550 Published online first on December 21, 2007
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