Search Results

You are looking at 1 - 10 of 2,718 items for :

  • Refine by Access: All Content x
Clear All

more often affected by MT than calm calves, 11 and cattle have been reported to have MT after a fall. 11 Rolling cattle to correct left displaced abomasum, 8 , 16 , 17 reducing uterine torsion using the plank-in-the-flank technique 18 and cesarean

Open access
in Journal of the American Veterinary Medical Association

time of first pull for BRD. Risk factors associated with BRD morbidity and mortality have been well researched. 6 Weight of incoming cattle to a feedyard, distance transported, time of the year, and more have been well-established markers for BRD

Open access
in American Journal of Veterinary Research

Feedlot cattle are frequently exposed to high environmental THIs during the summer months within cattle feeding regions of North America. Cattle performance is adversely affected by high temperatures. Cattle housed in unshaded areas have poor dry

Full access
in American Journal of Veterinary Research

Introduction Right heart failure (RHF) related deaths continue to be problematic for feeding operations and cattle owners due to unclear cause and insufficient ability to identify high risk individuals or cohorts. Historically RHF were only

Full access
in Journal of the American Veterinary Medical Association

Bovine respiratory disease represents substantial financial and animal health challenges for cattle producers. 1 It is a multifactorial disease complex caused by multiple viral and bacterial pathogens as well as environmental factors such as

Full access
in American Journal of Veterinary Research

Objective

To investigate the route of transmission of Neospora sp in a herd of dairy cattle in which sporadic abortions had been observed since the establishment of the farm in 1980.

Design

Serum samples were screened for antibodies to Neospora sp, and records from an artificial insemination program were analyzed.

Animals

58 female cattle.

Procedure

An ELISA was used to screen serum samples for antibodies to Neospora sp. Fertility, calf mortality, and relationships between specific cattle were investigated. Statistical analysis was performed on the fertility data.

Results

Antibodies were detected in 17 of 58 (29%) tested cattle. All seropositive cattle were descendants of 2 cows purchased in 1980. Cattle that were descendants of those 2 cows were compared with their herdmates, but significant differences were not detected in the number of inseminations per confirmed pregnancy or in the number of cattle that required more than 1 insemination/pregnancy. Since 1980, there were 323 confirmed pregnancies in the herd, and calf mortality (prenatal and perinatal mortality) was 24 of 323 (7%).

Clinical implications

Congenital transmission of Neospora organisms together with the apparent lack of horizontal transmission observed in the herd reported here indicated that Neospora sp has the ability to be transmitted from dam to offspring for several generations. This mode of transmission would explain the maintenance of infection in a population of cattle despite the lack of a definitive host for the parasite. (J Am Vet Med Assoc 1996;208:1441-1444)

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective

To compare muscle fluid with serum samples for detection of antibodies to Salmonella lipopolysaccharide.

Sample Population

Muscle fluid and serum samples from 2 cattle populations: 1 from the island of Bornholm with no history of salmonellosis (n = 39), and the other from the S dublin-enzootic areas of Jutland (n = 144).

Procedure

Salmonella dublin (O:1,9,12), S typhimu-rium (O:1,4,5,12), and Salmonella O:9-blocking ELISA were used for testing the samples.

Results

In the S dublin ELISA, all serum and muscle fluid samples from cattle on the island of Bornholm had OD450 values well below the cutoff value (0.5). For samples obtained from cattle in the enzootic areas of Jutland, high correlation was found between serum and muscle fluid samples (r s = 0.89, P < 0.001). In addition, 19% (28/144) of the cattle had ELISA-positive muscle fluid and serum samples; 2% (3/144) had positive results for muscle fluid only, whereas 1 animal had positive results for serum only (κ = 0.91, P < 0.0001; sensitivity and specificity of 97%). The same samples had similar significant correlation in the S typhimurium ELISA (r s = 0.88, P < 0.001, κ = 0.7, P < 0.001; sensitivity of 73% and specificity of 98%) and the O:9-blocking ELISA (r s = 0.49, P < 0.001).

Conclusion and Clinical Relevance

Muscle fluid samples taken at slaughter can be used as a practical alternative to serum samples for surveillance of Salmonella infections in cattle. (Am J Vet Res I997;58;334-337)

Free access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the efficacy of coumaphos, an organophosphate (OP) acaricide, at concentrations up to 2 times higher than the highest concentration required by the US Eradication Program against all stages of an OP-resistant strain of Boophilus microplusin experimentally infested cattle.

Animals—16 tick-naïve 200-kg female Hereford calves.

Procedure—Four groups of cattle (4 calves/group) were all infested with Boophilus ticks 3 times before treatment. Each group was treated with coumaphos as follows: group 1, at 0.165% active ingredient (AI); group 2, at 0.299% AI; group 3, at 0.566% AI; and group 4, not treated. Following treatment, ticks were collected for 21 days. Ticks collected 1 to 7, 8 to 14, and 15 to 21 days after treatment were considered adults, nymphs, and larvae, respectively, at time of treatment.

Results—Overall control at 0.165, 0.299, and 0.566% AI was 52.9, 75.8, and 89.7%, respectively. Control of adults ranged from 4.3% at 0.165% AI to 73.5% at 0.566% AI. Control of nymphs ranged from 60.6% at 0.165% AI to 97.3% at 0.566% AI. Control of larvae was > 98% at all coumaphos concentrations.

Conclusions and Clinical Relevance—All coumaphos concentrations failed to provide acceptable control for use in the US Eradication Program against OPresistant ticks. Treatment was least effective against adults and most effective against larvae. Even at 0.566% AI (2 times higher than required by the US Eradication Program), ticks were not eradicated, placing the United States at risk from dispersing cattle harboring viable ticks to uninfested areas. (Am J Vet Res 2003;64:684–689)

Full access
in American Journal of Veterinary Research

Summary

The Cooper isolate of bovine herpesvirus-1, which causes abortion in cattle, was used to construct a thymidine kinase- negative (tk- ) deletion mutant virus. Twelve heifers were inoculated iv at 25 to 29 weeks of pregnancy with either tk- or thymidine kinase-positive (tk+ ) Cooper virus. All heifers developed fevers of 1 to 2 C during the first week after inoculation. Temperatures of tk+ inoculates were slightly higher and remained above normal a few days longer than in tk- inoculates. Viremia was detected in 5 of 6 tk+ inoculates and in all 6 tk- inoculates. More virus isolations were made from nasal and vaginal swab specimens of tk+ inoculates than from swab specimens of tk- inoculates. All heifers developed virus neutralizing antibody within 14 days after inoculation and antibody titers were similar between the 2 groups. None of the tk- inoculated heifers aborted and their calves did not have neutralizing antibody at birth. Abortion occurred in 5 of 6 heifers given tk+ virus. All aborted fetuses were infected with bovine herpesvirus-1, as demonstrated by virus isolation or detection of viral antigen in fetal tissues. These results indicate that inactivation of the tk gene reduces abortifacient activity of bovine herpesvirus-1.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine efficacy of vaccines incorporating QuilA, alum, dextran combined with mineral oil, or Freund adjuvant for immunization of feedlot cattle against Streptococcus bovis and Lactobacillus spp.

Animals—24 steers housed under feedlot conditions.

Procedure—Steers were randomly assigned to 4 experimental groups and a control group. Animals in experimental groups were inoculated on days 0 and 26 with vaccines containing Freund adjuvant (FCA), QuilA, dextran combined with mineral oil (Dex), or alum as adjuvant. Serum anti-S bovis and anti- Lactobacillus IgG concentrations were measured, along with fecal pH, ruminal fluid pH, and number of S bovis and Lactobacillus spp in ruminal fluid.

Results—Throughout the study, serum anti-S bovis and anti-Lactobacillus IgG concentrations for animals in the Dex, QuilA, and alum groups were similar to or significantly higher than concentrations for animals in the FCA group. Serum anti-S bovis and anti-Lactobacillus IgG concentrations were significantly increased on days 26 through 75 in all 4 experimental groups, and there was a linear relationship between anti-S bovis and anti-Lactobacillus IgG concentrations. For animals in the QuilA and Dex groups, mean pH of feces throughout the period of experiment were significantly higher and numbers of S bovis and Lactobacillus spp in ruminal fluid on day 47 were significantly lower than values for control cattle.

Conclusions and Clinical Relevance—Results suggest that immunization of feedlot steers against S bovis and Lactobacillus spp with vaccines incorporating Freund adjuvant, QuilA, dextran, or alum as an adjuvant effectively induced high, long-lasting serum anti-S bovis and anti-Lactobacillus IgG concentrations. Of the adjuvants tested, dextran may be the most effective. (Am J Vet Res 2000;61;839–843)

Full access
in American Journal of Veterinary Research