J. G. Powell

Effects of on-arrival versus delayed clostridial or modified live respiratory vaccinations on health, performance, bovine viral diarrhea virus type I titers, and stress and immune measures of newly received beef calves.

Stress, commonly associated with weaning, marketing, and shipment of feeder cattle, can compromise immune function, and vaccine administration during immunosuppression may reduce vaccine efficacy and calf growth. Four treatments were compared in a 2 x 2 factorial arrangement to evaluate the effect of on-arrival (d 0) vs. delayed (d 14) administration of clostridial (CLOS) and respiratory (RESP) vaccines on health, performance, bovine viral diarrhea virus (BVDV) antibody titers, and physiological immune measurements of high-risk, newly received calves. Crossbred bull and steer calves (n = 263) were weighed (239 +/- 1.2 kg), stratified by sex, and randomly assigned to vaccination treatment: 1) arrival CLOS, arrival RESP (ACAR); 2) arrival CLOS, delayed RESP (ACDR); 3) delayed CLOS, arrival RESP (DCAR); and 4) delayed CLOS, delayed RESP (DCDR). Body weight and blood samples were collected on d 0, 14, 28, 42, and 56. Average daily gain did not differ (P > or = 0.34), averaging 0.98, 0.93, 0.95, and 0.91 kg/d for ACAR, ACDR, DCAR, and DCDR, respectively, for the entire 56-d trial. Vaccination timing did not affect morbidity (P > or = 0.23); however, there tended to be a CLOS timing effect (P = 0.07) and RESP timing effect (P = 0.09) on days to initial bovine respiratory disease (BRD) treatment. Average days to initial BRD treatment were less for ACAR (6 +/- 0.8 d) compared with DCDR (8 +/- 0.8 d; P = 0.01). Greater white blood cell counts were observed for DCDR than ACDR (P = 0.01), with ACAR and DCAR being intermediate. Serum cortisol concentrations were greater on d 0 than d 14 (P < 0.01) or d 28 (P = 0.01) but no treatment x day interaction (P = 0.21) was observed. Timing of RESP administration affected (P = 0.001) serum BVDV type I titers, with greater (P < 0.01) levels in calves receiving RESP vaccine on arrival. Delaying CLOS or RESP vaccination did not affect BW gain or morbidity in high risk, newly received stocker calves. Calves administered RESP vaccine on d 0 developed antibody titers to BVDV type I earlier than delayed RESP treatments. Total white blood cell count was greatest when RESP and CLOS vaccination were delayed (DCDR).

Effect of surgical castration with or without oral meloxicam on the acute inflammatory response in yearling beef bulls.

Pain management and welfare are increasingly prevalent concerns within animal agriculture. Analgesics may alleviate pain and inflammation associated with castration of beef cattle. This study was conducted to elucidate the effects of surgical castration on the acute inflammatory response and immunomodulation and whether concurrent oral administration of meloxicam (1 mg/kg BW) would alter these responses. On d -1, crossbred bull calves ( = 30; initial BW = 227.4 ± 10.3 kg) were fitted with indwelling jugular catheters and rectal temperature (RT) recording devices, placed into individual stanchions, and randomly assigned to 1 of 3 treatments. Treatment application occurred at h 0 and consisted of 1) intact bull calves treated with sham castration (CON), 2) bulls surgically castrated without meloxicam administration (CAS), and 3) bulls surgically castrated with oral meloxicam (1 mg/kg BW) administration (MEL). Blood samples were collected at 0.5-h intervals from h -2 to 4, 1.0-h intervals from h 4 to 8, and 12-h intervals from h 12 to 72. Serum was analyzed for cortisol and haptoglobin (Hp) concentrations using ELISA. Whole blood was analyzed for complete blood counts at -2, 0, 2, 4, 6, 8, 12, 24, 36, 48, 60, and 72 h, and RT was recorded in 5-min intervals. Postcastration RT was greatest for MEL (39.04), intermediate for CAS (38.99), and least for CON (38.93°C; ≤ 0.01). Serum cortisol was increased ( < 0.001) for CAS (12.3) and MEL (11.3) compared with CON (6.7 ng/mL) during the postcastration period. At 0.5 and 1.5 h, cortisol concentration was greater in CAS and MEL than CON, whereas at 2 and 2.5 h, cortisol concentration was greatest for CAS, intermediate for MEL, and least for CON (treatment × time, < 0.001). Total white blood cell ( ≤ 0.04), lymphocyte ( ≤ 0.02), and monocyte ( ≤ 0.002) counts were greatest for CAS, intermediate for MEL, and least for CON. Administration of MEL reduced ( ≤ 0.002) eosinophil counts during the postcastration period when compared with CON and CAS. The change in serum Hp, relative to baseline values, was reduced for MEL at 36 ( < 0.01) and 60 h ( ≤ 0.03), and the overall Hp concentration was least for MEL ( < 0.001). Oral administration of meloxicam at the time of castration reduced the acute inflammatory response in castrates, as evidenced by a reduction in Hp and certain leukocyte concentrations; it also caused a delayed increase in RT. Further research is needed to determine if this reduced acute inflammatory response would equate to improved health and/or performance after castration.

Effect of castration timing and oral meloxicam administration on growth performance, inflammation, behavior, and carcass quality of beef calves.

Beef bull calves (n = 62) were assigned randomly, within sire breed, to 1 of 4 treatments at birth. Treatments were 1) surgical castration near birth, 2) surgical castration near birth with oral administration of meloxicam (1 mg/kg BW), 3) surgical castration at weaning (WNG), or 4) surgical castration at weaning with oral administration of meloxicam (1 mg/kg BW; WMX). A subset of calves (n = 7/treatment group) were selected randomly near birth for blood collection, behavioral analyses, and rectal temperature (RT) records for a 7-d postcastration period on d 0 (birth), 1, 3, and 7, and on d 214 (weaning), 214 + 6 h, 215, 217, 221, and 228. Calf standing and lying activity were monitored from the same subsets by recording x- and y-axis positions of an accelerometer attached to the right metatarsus for 7 d postcastration. Calf BW was recorded throughout the entire production cycle, and carcass data were collected at slaughter. For statistical analyses, bulls left intact at birth were considered a positive control (BUL) for observations that occurred before their treatment application at weaning; likewise, bulls castrated at birth were considered a negative control (STR) during postweaning observations. No difference (P > 0.88) occurred in ADG between treatments throughout the preweaning period (d 0 to 214); however, 56-d postweaning ADG was greatest ( P= 0.02) in STR, intermediate in WMX, and least in WNG. At weaning, haptoglobin (Hp) was greater (P ≤ 0.005) for WNG and WMX compared to STR on d 214+6 h, 215, and 217, and Hp was greater (P = 0.05) in WNG compared to WMX on d 217. Neutrophils increased (P < 0.001) and red blood cells decreased (P ≤ 0.03) for WNG and WMX on d 214+6 h and 217, respectively. Postweaning behavior observations indicated that STR calves spent the least proportion of time standing (P = 0.002) when compared to WNG and WMX. Furthermore, WMX calves exhibited a greater proportion of time spent standing (P = 0.03) compared to WNG. Grazing and finishing phase ADG and carcass measurements did not differ (P ≥ 0.24) across treatments. In this study, surgical castration at weaning, but not near birth, altered the acute phase response, behavior, and growth performance. Oral meloxicam reduced serum Hp and improved ADG briefly when administered to calves castrated at weaning. Oral administration of meloxicam may be efficacious for mitigating some of the stress and inflammation associated with castration of weaning-age bull calves.

Weaning management of newly received beef calves with or without continuous exposure to a persistently infected bovine viral diarrhea virus pen mate: Effects on health, performance, bovine viral diarrhea virus titers, and peripheral blood leukocytes1

ABSTRACT Exposure to animals persistently infected (PI) with bovine viral diarrhea virus (BVDV) results in immunomodulation of cohorts that may have health and growth consequences; however, effects may differ in low-risk, preconditioned (PC) vs. high-risk, auction market (AM) beef cattle. Our objective was to compare health and performance of PC or AM management systems with (PI) or without (CON) presence of a PI-BVDV pen mate using a 2 × 2 factorial arrangement. Four shipment blocks of crossbred PC steers (n = 236) from 3 ranch-origins were weaned, dewormed, vaccinated, tested for PI-BVDV, and kept on the ranch for ≥42 d. Subsequently, PC steers were transported to a stocker receiving unit (RU), weighed (251 ± 2 kg), blood sampled, stratified by d −1 BW, and assigned randomly to treatment (PCPI or PCCON) with no additional processing. Simultaneously, 4 blocks of crossbred AM calves (n = 292) were assembled from regional auction markets and transported to the RU ± 36 h from PC arrival. The AM calves were weighed (245 ± 1.3 kg), stratified by gender and d −1 BW, processed under the same regimen used for PC steers at their origin ranch except bull calves were castrated, and then assigned randomly to treatment (AMPI or AMCON). Treatment pens (0.45 ha) were arranged spatially such that PI did not have fence-line or water source contact with CON. Calves were fed identically and followed the same antibiotic treatment protocol. Daily BW gain for the entire 42-d receiving trial was greater (P < 0.001) for PC (1.2 kg) compared with AM (0.85 kg). There was an exposure effect (P = 0.002) on ADG from d 28 to 42; CON gained 1.12 kg vs. 0.90 kg BW for PI cohort. Morbidity was markedly greater (P < 0.001) in AM (70%) vs. PC (7%), resulting in (P < 0.001) an antibiotic treatment cost of

Association of hematologic variables and castration status at the time of arrival at a research facility with the risk of bovine respiratory disease in beef calves

20.52 and

Fecal egg count reduction and control trial determinations of anthelmintic efficacies for several parasiticides utilizing a single set of naturally infected calves.

2.48/animal, respectively. Treatment with a third antibiotic occurred more often (P = 0.04) for PI cohort, and the percentage of chronically ill cattle was greatest (P = 0.06) for AMPI. Upon arrival, BVDV type 1a, 1b, and 2a titers were greater for PC (treatment × day, P < 0.001), and the percentage seropositive to BVDV type 1a on d 0 was 100% for PC vs. 23% in AM. Platelets increased transiently (P < 0.001) with greater platelets observed in AM (P < 0.001). Results indicate that PC calves gain faster and require fewer antibiotic treatments during the receiving period. Exposure to PI reduced BW gain from d 28 to 42, increased the number of calves treated thrice, and increased chronically ill cattle for AM.

Control trial and fecal egg count reduction test determinations of nematocidal efficacies of moxidectin and generic ivermectin in recently weaned, naturally infected calves

OBJECTIVE To determine the association of CBC variables and castration status at the time of arrival at a research facility with the risk of development of bovine respiratory disease (BRD). DESIGN Retrospective cohort study. ANIMALS 1,179 crossbred beef bull (n = 588) and steer (591) calves included in 4 experiments at 2 University of Arkansas research facilities. PROCEDURES Calves underwent processing and treatments in accordance with the experiment in which they were enrolled. Castration status and values of CBC variables were determined at the time of arrival at the facilities. Calves were monitored to detect signs of BRD during a 42-day period. RESULTS The areas under the receiving operator characteristic curves for CBC variables with significant contrast test results ranged from 0.51 (neutrophil count) to 0.67 (eosinophil count), indicating they were limited predictors of BRD in calves. The only CBC variables that had significant associations with BRD in calves as determined via multivariable logistic regression analysis were eosinophil and RBC counts. The odds of BRD for bulls were 3.32 times the odds of BRD for steers. CONCLUSIONS AND CLINICAL RELEVANCE Results of this study indicated that low eosinophil and high RBC counts in blood samples may be useful for identification of calves with a high risk for development of BRD. Further research may be warranted to validate these variables for prediction of BRD in calves. Calves that were bulls at the time of arrival had a higher risk of BRD, versus calves that were steers at that time.

Effect of growth implant regimen on health, performance, and immunity of high-risk, newly received stocker cattle

In this study, a single set of naturally infected calves was used for the conduct of a fecal egg count reduction test (FECRT) immediately followed by a control trial; all, to evaluate the efficacies of several commonly used, non-generic anthelmintics. Ten animals were allocated into each of the five treatment groups; untreated control (UTC), injectable 1% moxidectin given at 0.2 mg kg(-1)BW (MXD), injectable 1% ivermectin given at 0.2 mg kg(-1)BW (IVM), 9.06% oxfendazole given orally at 4.5 mg kg(-1)BW (OXF), and 10.0% fenbendazole given orally at 5.0 mg kg(-1)BW (FBZ). Confinement of animals to clean, concrete-floored pens was initiated on day -7 and continued until animal necropsy (2 animals were necropsied per treatment group per day on days 35-39 for nematode collections). All treatments were given on day 0, and the FECRT was conducted on all animals until necropsy. From days 2 to 14, FECR %s for the combined strongyle egg counts were >or=90% for all anthelmintic groups. At the time of necropsy, FECRT %s for the combined strongyle egg counts continued to be >or=90% for all treatments with the exception of IVM (84%). After adjustment of the strongyle egg counts in accordance with coproculture larvae percentages, FECRT %s at the time of necropsy for Haemonchus, Ostertagia and Cooperia were found to be >or=94% for MXD and OXF, but <90% for FBZ (Ostertagia) and IVM (Haemonchus and Cooperia). At necropsy, more than six of the ten untreated animals were infected with Ostertagia ostertagi (adults, EL(4) and LL(4)), and adult Haemonchus placei, Trichostrongylus axei, Cooperia oncophora, C. surnabada and C. punctata. Based on geometric means: all of the above populations were removed by >or=96% by MXD; were removed by >or=90% by IVM except for O. ostertagi LL(4) (81.9%), C. oncophora and C. surnabada adults (77.4%) and C. punctata adults (84.8%); were removed by >or=90% by OXF except for O. ostertagi adults, EL(4) and LL(4) (89.9, 70.2 and 48.1%, respectively); and were removed by >or=90% by FBZ except for O. ostertagi adults, EL(4) and LL(4) (72.5, 0.0 and 21.9%, respectively). Judging from the above data, FECR and control trial results can be extremely similar given the proper experimentation and, despite varied degrees of nematode resistance, targeted nematode burdens commonly carried by Midwestern beef cattle are effectively removed by the parasiticides that are available today.

Supplemental trace minerals (zinc, copper, and manganese) as sulfates, organic amino acid complexes, or hydroxy trace-mineral sources for shipping-stressed calves

An anthelmintic efficacy study was performed with young, naturally infected beef-type calves obtained at local farms. Presumably, the study calves had been recently weaned and had not been treated with a parasiticide prior to study acquisition. After blocking the 24 study calves in accordance with calculated Cooperia spp EPG counts, the calves were randomly allocated within each block to one of four treatment groups, resulting in 6 animals per treatment group (untreated controls, topical ivermectin at the rate of 500 mcg/kg BW [Noromectin Pour-On(®) Norbrook], topical moxidectin at the rate of 500 mcg/kg BW [Cydectin Pour-On(®) Boehringer Ingelheim Vetmedica (BIVM)] and injectable moxidectin at the rate of 200 mcg/kg BW [Cydectin(®) BIVM]. After treatment, the animals were penned by treatment group until necropsy. Fecal, strongyle egg count reduction percentages at 2 days post-treatment were 13, 52, 81 and 93 for control, topical ivermectin, topical moxidectin and injectable moxidectin treatment groups, respectively. In the same order as above, egg count reduction percentages at necropsy (15-18 days post-treatment) were -14, 91, 94 and 97. Based on geometric means for worm burdens quantified at necropsy, anthelmintic efficacies ranged from 96 to 100% for adult Oesophagostomum radiatum, Ostertagia ostertagi, Haemonchus placei and Trichostrongylus axei. Against adult Nematodirus helvetianus, percent efficacies based on geometric means were 56.7, 98.3 and 82.2 for topical ivermectin, topical moxidectin and injectable moxidectin, respectively; an observation that is guarded, as only 5 control animals were infected with adult N. helvetianus. Respective anthelmintic efficacies (%s) against adult Cooperia oncophora and C. punctata were 93.0 and 73.4 (topical ivermectin), 99.3 and 99.9 (topical moxidectin) and 46.1 and 93.6 (injectable moxidectin). Judging from these data, it appears that treatment of calves soon after weaning with topical moxidectin is effective (>90% efficacy) for all common nematodes in cattle, but injectable moxidectin and topical ivermectin have limited effectiveness against Cooperia spp. With Cooperia spp and H. placei infections, the fecal egg count reduction test and the control trial determinations of anthelmintic effectiveness were in disagreement regarding injectable moxidectin and topical ivermectin.

Weaning management of newly received beef calves with or without continuous exposure to a persistently infected bovine viral diarrhea virus pen mate: effects on rectal temperature and serum proinflammatory cytokine and haptoglobin concentrations.

Growth implant efficacy may be affected when administered to nutritionally stressed calves, whereas the procedure may alter health or the humoral immune response to respiratory vaccination. The study objective was to determine the effect of different administration times (d 0, 14, or 28) of a growth implant containing 200 mg progesterone and 20 mg estradiol benzoate on health, performance, and metabolic and immunologic variables in high-risk, newly received beef calves used in a 120-d receiving/grazing stocker system. Crossbred bull and steer calves ( = 203) were weighed (initial BW = 203 ± 2.7 kg), stratified by castrate status on arrival, and randomly assigned to experimental treatments consisting of 1) negative control (no growth implant administered), 2) growth implant administered on d 0, 3) growth implant administered on d 14, and 4) growth implant administered on d 28. There were no differences ( ≥ 0.16) in BW or ADG during the 42-d receiving period. However, ADG during the subsequent grazing period and overall was greater ( ≤ 0.01) for implanted calves versus the negative control. Growth implant timing did not affect the rate of clinical bovine respiratory disease morbidity ( = 0.52; 94% morbidity overall) or bovine viral diarrhea virus type 1a antibody titer concentration ( = 0.61). Indicative of an overall negative energy balance on arrival, NEFA decreased sharply subsequent to d 0 (day effect, < 0.001), but was not affected ( = 0.47) by the timing of growth implantation. Blood urea N concentrations increased transiently (day effect, < 0.001); however, no treatment effect was observed ( = 0.72). Therefore, under conditions of this study, the timing of growth implant administration did not affect growth implant efficacy, health, or metabolic or immunologic variables in newly received, high-risk beef stocker calves. Overall, our observations suggest that there is not a clear benefit to delaying growth implantation and that a growth implant does not affect health or vaccine response in newly received beef calves.