Search Results

Summary

Goats from 28 states were tested for antibodies to caprine arthritis-encephalitis virus. Of 3,790 goats, 1,175 (31%) tested positive, and of 196 herds tested, 143 (73%) had 1 or more seropositive members. This prevalence, based on serum samples from all goats in the participating herds, was lower than most rates reported in other studies. Such studies were based on fewer samples, incomplete sampling of herds, or smaller geographic base. Prevalence was highest in western Pacific and northern plains regions, increased with age to 3 years, was highest among goats on family-owned farms, and was lowest in the Angora breed. Differences in prevalence were not related to gender or size of herd.

Summary

Ovine progressive pneumonia (opp) is a lentivirus-induced disease of sheep in the United States that is similar, if not identical, to maedi/visna in many other countries. Prevalence estimates of seropositivity to this virus in sheep in the United States have been confined to limited groups or flocks of sheep and have varied from 1 to 90%. In this study of detection of antibodies against opp virus, we found a lower general prevalence of antibodies to opp virus in sheep than was previously reported. Of 16,827 sheep from 29 states in the United States, 26% were seropositive and 48% of 164 flocks that were tested had 1 or more seropositive sheep. Seropositivity to opp virus for sheep within special categories was determined, although nonrandom samples that were available may have biased the results. Within regions of the United States, prevalence was highest in the Rocky Mountain region at 49% and lowest in the northern Atlantic region at 9%. Seropositive sheep were not evenly distributed among flocks, but were clustered in a few flocks of sheep. A high number of flocks had no or few seropositive sheep. Prevalence increased with age from 4% at < 1 year to a plateau of 34% at 4 years. Seropositivity was variable among breeds and was not associated with sex, wool class, or place of origin of ancestors.

Summary

An epizootic of subclinical and clinical mastitis caused by Serratia marcescens was investigated in a 1,000-cow dairy farm in California. Serratia marcescens was isolated from 13 to 18% of composite milk samples obtained from lactating dairy cows. During monthly milk sampling performed during a 4-month period, S marcescens was isolated from 38.8 to 62.3% of composite milk samples obtained from cows from which S marcescens was previously isolated. Few cows infected with S marcescens had evidence of clinical mastitis. Somatic cell count value was associated with isolation of S marcescens. Cows with somatic cell counts > 500,000 were 5.48 times as likely to have intramammary infections with S marcescens, compared with cows with somatic cell count ≤ 500,000. Lactation number also was associated with S marcescens intramammary infection. After adjusting for the effect of lactation number, cows with high somatic cell count values were 2.98 times as likely to have intramammary infection with S marcescens, compared with cows with low somatic cell counts. Infection with S marcescens was independent of days in lactation, production string, and daily milk production. Eleven months after the beginning of the epizootic, S marcescens was isolated from organic bedding samples obtained from the dairy. Despite numerous attempts, other sources of S marcescens could not be identified on this dairy.

Summary

Body condition scoring (using a 5-point scale with quarter-point divisions) was performed on 66 Holstein dairy cows that began their second or later lactation in August, September, or October 1988. Body condition was scored, beginning on postpartum day 4(± 1) and subsequently at postpartum days (± 1) 18, 32, 46, 60, 73, and 87. Blood samples were obtained on the same dates. Kilograms of milk produced per cow was measured daily. Body condition score and changes in body condition score were evaluated in relation to daily milk production, cumulative 80- day milk yield, and serum urea nitrogen and cholesterol concentrations.

Average daily milk production during week 1 was indicative of cumulative 80-day production, but not of 305- day milk yields. Cows that calved with body condition score ≥ 3.50 did not differ in average daily milk production, cumulative 80-day milk yield, or 305-day milk yield, compared with cows that calved with body condition score < 3.50. Cows that calved with body condition score ≥ 3.50 lost more condition than did cows that calved with body condition score < 3.50. Body condition score at calving and amount of body condition loss interacted with the rate of change in daily milk production.

Serum urea nitrogen concentration did not differ for cows grouped by cumulative 80-day milk production or for cows grouped by amount of condition loss. Serum cholesterol values were higher than previously reported values and increased directly with milk production. Serum cholesterol values were inversely related to condition loss, but changes in cholesterol concentration were not related to condition loss.

Summary

Body condition scoring (using a 5-point scale with quarterpoint divisions) was performed on 66 Holstein dairy cows that began their second or later lactation in August, September, or October 1988. Cows’ body condition was scored beginning on postpartum day 4 (± 1) and subsequently at postpartum days (± 1) 18, 32, 46, 60, 73 and 87. Blood samples were obtained on the same dates. Reproductive health examinations were conducted by 1 of 2 veterinarians beginning at postpartum day 21. Reproductive performance was evaluated in relation to body condition score and serum urea nitrogen and cholesterol concentrations.

Number of days to first recorded signs of estrus and first breeding were not related to body condition score at calving, amount of condition loss, cumulative 80-day milk yield, or 305-day fat corrected milk yield. Cows that calved with body condition score ≥ 3.50 required more days to conceive. Cows losing > 0.75 points of condition had longer days of conception. Body condition score at calving and amount of condition lost were not related to services per conception or diagnosis of follicular cyst.

Cumulative 80-day milk yield was not related to days to conception or services per conception. Cows that produced = the mean 305-day milk yield required more services and had longer days to conception than cows that produced < the mean 305-day milk yield. Cows with diagnosis of ovarian follicular cysts had greater cumulative 80- and 305-day milk yields than did cows that were not diagnosed with follicular cysts.

Cows conceiving with ≤ 2 services did not differ in average daily milk production, body condition score, or serum urea nitrogen concentration from cows conceiving with > 2 services, but cows that conceived with ≤ 2 services had higher serum cholesterol values than did cows requiring more services.

Summary

Metabolic and production responses are reported for 72 cows treated with bovine somatotropin (bst) for 30 days starting at day 70 of lactation. Of these 72 cows, 48 had been exposed in the preceding lactation to long-term treatment with bst at 3 dosages and 24 (controls) had not been given bst. Approximately half of the cows in each group were parity-2 cows, the rest were older. Comparisons between groups were made separately for parity-2, and older cows.

Analyses, using pretreatment values of each variable as a covariate, indicated that older cows, but not parity-2 cows, significantly (P < 0.05) increased milk production during treatment. Parity-2 cows, however, had a significantly higher milk fat percentage than controls following treatment. Cows treated with 51.6 or 86 mg bst/d in both parity groups had significantly higher serum-free fatty acids than controls. Estimated net energy balances were significantly lower for older treated cows, but did not significantly differ from controls for parity-2 treated cows. Older cows in the 86 mg of bst/d group tended to have higher concentrations of blood glucose than did older control-group cows. Treatment with bst did not significantly increase serum ketone concentrations in any group of animals, and none of the cows developed clinical ketosis during this period.

Estimated net energy balance (eneb) during treatment was a significant (P < 0.05) covariate for free fatty acid concentrations in older cows and for milk fat percentage in parity-2 cows. Covariate adjusted analyses, using eneb during treatment as a covariate, indicated that lipolytic stimuli already acting may be enhanced by treatment with bst, but a negative energy balance was not a necessary precondition for free fatty acid concentrations to increase following somatotropin treatment. Similarly, milk fat percentages for parity-2 treated cows were significantly (P < 0.05) higher during treatment than controls when eneb during treatment was used as a covariate.

Increased milk fat concentrations in parity-2 treated cows were not associated with significant increases in the ratio of C₁₈:C_4-10 milk fatty acids, indicating that increased milk fat resulted from either an increase in incorporation of C₁₈ fatty acids into milk fat coupled with an increase in de novo mammary synthesis of C_4-10 milk fatty acids or an increase in C_12-16 fatty acids that may arise either from increased tissue mobilization, from diet, or from de novo mammary synthesis.

Abstract

Objective—To test the life-sparing and therapeutic effect of a parenterally administered virus-specific antiviral phosphorodiamidate morpholino oligomer (PMO) for treating kittens during outbreaks of severe viral disease.

Animals—112 kittens of various sex and age in 4 trials involving 3 outbreaks of naturally developing caliciviral disease.

Procedures—Each trial provided an opportunity to investigate the disease. A calicivirus isolated from the liver of a cat that died with hemorrhage and hepatitis was sequenced, and a PMO that had sequence specificity complementary to a 5' region was synthesized. In vitro efficacy of the PMO was tested against the isolate, followed by 3 trials in outbreaks of severe caliciviral disease. The PMO was administered starting on day 1 of disease onset (0.7 to 5.0 mg/kg, SC, q 24 h) and continuing for up to 7 days. Survival time, clinical recovery, and caliciviral shedding were compared by use of various antiviral dosages. In a fourth trial involving nonfatal disease, a control treatment was administered for comparison.

Results—In vitro blockage of caliciviral replication by the PMO was dose dependent. In trials 1 to 3 in which survival was the endpoint, 47 of 59 cats receiving PMO survived but only 3 of 31 survived without PMO treatment. Antiviral treatment reduced viral shedding and hastened clinical recovery, as measured by weight gains and clinical condition.

Conclusions and Clinical Relevance—These data provided evidence that virus-specific PMOs were effective in treating kittens with severe Vesivirus disease and suggested a broader application for other viruses and species, including humans.