Passive immunity stimulated by vaccination of dry cows with a Salmonella bacterial extract.

BACKGROUND: Diarrhea because of Salmonella infection is a cause of neonatal calf diarrhea. The stimulation of passive immunity in the calf by vaccinating the dam for Salmonella has shown some success in previous studies; however, there are no data on the use of currently licensed vaccines in the United States. OBJECTIVE: To determine whether vaccinating cows at dry-off with a commercially available Salmonella bacterial extract would stimulate Salmonella-specific antibodies in the colostrum of cows at calving and whether these antibodies would be transferred to the calf. ANIMALS: Sixty Holstein cattle and 59 calves from a herd presumed to be naïve to Salmonella. METHODS: Prospective clinical trial. Thirty cows were vaccinated at dry-off with a Salmonella enterica serovar Newport bacterial extract and again 4 weeks later. An additional 30 cows received only saline. Calves fed fresh colostrum from their dam within 4 hours of birth had blood collected 24 hours later. RESULTS: Vaccinated cattle had increased Salmonella Newport antibody titers at calving in blood (P = .01) and colostrum (P = .011). Calves that received colostrum from vaccinated cattle also had significant increase in Salmonella antibodies (1.04 ± 0.03) as compared to calves born to unvaccinated cows (0.30 ± 0.02). CONCLUSIONS AND CLINICAL IMPORTANCE: The results indicate that the use of a commercially available Salmonella vaccine can stimulate antibodies that are passed on to the calf via colostral transfer. Further studies need to be done to determine whether these antibodies will offer protection against Salmonella challenge.

Escherichia coli O157:H7 shedding in vaccinated beef calves born to cows vaccinated prepartum with Escherichia coli O157:H7 SRP vaccine.

Extensive research, intervention equipment, money, and media coverage have been directed at controlling Escherichia coli O157:H7 in beef cattle. However, much of the focus has been on controlling this pathogen postcolonization. This study was conducted to examine the performance, health, and shedding characteristics of beef calves that were vaccinated with an E. coli O157:H7 SRP bacterial extract. These calves had been born to cows vaccinated prepartum with the same vaccine. Cows and calves were assigned randomly to one of four treatments: (i) neither cows nor calves vaccinated with E. coli O157:H7 SRP (CON), (ii) cows vaccinated with E. coli O157:H7 SRP prepartum but calves not vaccinated (COWVAC), (iii) calves vaccinated with E. coli O157:H7 SRP but born to cows not vaccinated (CALFVAC), (iv) cows vaccinated with E. coli O157:H7 SRP prepartum and calves also vaccinated (BOTH). Calves born to vaccinated cows had significantly higher titers of anti-E. coli O157:H7 SRP antibodies (SRPAb) in circulation at branding time (P < 0.001). Upon entry to the feedlot, overall fecal E. coli O157:H7 prevalence was 23 % among calves, with 25 % in the CON treatment group, 19 % in the CALFVAC group, 32 % in the COWVAC group, and 15 % in the BOTH group (P > 0.05). Fecal shedding of E. coli O157 on arrival to the feedlot was not correlated with fecal shedding at slaughter (Spearman's rho = -0.02; P = 0.91). No significant effects of cow or calf E. coli O157:H7 SRP vaccination treatment were found on feedlot calf health or performance (P > 0.05), prevalence of lung lesions or liver abscess (P > 0.05), or morbidity, retreatment, or mortality numbers (P > 0.05). The findings of this study indicate that the timing of vaccination of calves against E. coli O157:H7 may be an important consideration for maximizing the field efficacy of this vaccine.

Analysis of modern technologies commonly used in beef cattle production: conventional beef production versus nonconventional production using meta-analysis.

Conventional feeding systems use pharmaceutical products not allowed in natural or organic systems for finishing cattle. This review of data compares the performance effects (ADG, G:F, DMI) of technologies used in conventional feeding programs that are prohibited in organic programs, natural programs, or both. The technologies evaluated were steroid implants, monensin, tylosin, endectocides, and metaphylaxis with any antimicrobial. For inclusion in this analysis, studies were conducted in North America, reported randomization to treatment group, used beef cattle, contained an untreated control group, and were sourced from peer-reviewed journals. Forest plots were used to examine the data visually for trends toward a uniform effect of the technology on the outcomes of interest (ADG, DMI, G:F). Technologies that displayed a uniform response on the forest plot compared with negative controls were then analyzed using mixed models. Examination of forest plots for endectocides, steroid implants, monensin, and metaphylaxis technologies appeared to show performance advantages for treated cattle relative to cattle in negative control groups. An insufficient number of studies met the inclusion criteria to conduct meta-analyses comparing endectocides, monensin, or tylosin with negative controls. Average daily gain in feeder cattle given metaphylaxis on arrival was 0.11 kg/d (P < 0.01) greater relative to cattle that did not receive metaphylaxis on arrival. Implanting heifers increased ADG by 0.08 kg/d compared with nonimplanted controls (P = 0.09). Implants had no effect on G:F (P = 0.14) in heifers or on DMI (P = 0.44) relative to nonimplanted control heifers. Implanting steers was associated with greater ADG, by 0.25 kg/d (P < 0.01), and DMI, by 0.53 kg/d (P < 0.01), relative to nonimplanted control steers. Implants also improved G:F in steers relative to nonimplanted steers, by 0.02 (0.17 vs. 0.15; implanted vs. controls, P < 0.01; n = 21 studies). When average estimated differences in ADG and G:F for implanted and nonimplanted steers were incorporated into a breakeven model, implanted steers had a $77/animal lower cost of production than nonimplanted steers and a $349/animal lower cost of production than organically raised steers. These data illustrate the importance of capturing premiums when operating natural and organic production systems to maintain economic viability.