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  • Author or Editor: Charles A. Holmberg x
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Abstract

Objective—To evaluate fecal shedding of Giardia duodenalis, Cryptosporidium parvum, Salmonella organisms, and Escherichia coli O157:H7 from llamas in California with respect to host factors and management practices.

Animals—354 llamas from 33 facilities.

Procedure—Fecal specimens were collected and examined for G duodenalis and C parvum by means of immunofluorescent microscopy. Salmonella organisms were cultured by placing feces into selenite enrichment broth followed by selective media. Escherichia coli O157:H7 was cultured by use of modified tryptocase soy broth followed by sorbitol MacConkey agar, with suspect colonies confirmed by means of immunofluorescent microscopy.

Results—12 of 354 fecal specimens (3.4%) had G duodenalis cysts. Younger llamas (crias) were more likely to be shedding cysts, compared with older llamas. Farm-level factors that increased the risk of shedding were large numbers of yearlings on the property (> 10), smaller pen sizes, large numbers of crias born during the previous year (> 10), and large pen or pasture populations (> 20). None of the 354 fecal specimens had C parvum oocysts. Seventy-six (from 7 facilities) and 192 (from 22 facilities) llamas were tested for Salmonella organisms and E coli O157:H7, respectively. All fecal specimens had negative results for these bacteria.

Conclusion and Clinical Relevance—Shedding of G duodenalis was primarily limited to crias 1 to 4 months old. Llamas from properties with large numbers of crias born in the previous year, resulting in large numbers of yearlings in the current year, were at greater risk of infection. In addition, housing llamas in smaller pens or pastures and managing llamas and crias in large groups also increased the risk of G duodenalis shedding. (Am J Vet Res 2001;62:637–642)

Full access
in American Journal of Veterinary Research

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:C4-10 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 C4-10 milk fatty acids or an increase in C12-16 fatty acids that may arise either from increased tissue mobilization, from diet, or from de novo mammary synthesis.

Free access
in American Journal of Veterinary Research

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.

Free access
in American Journal of Veterinary Research

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.

Free access
in American Journal of Veterinary Research

Abstract

Objective—To determine the prevalence of Salmonella spp in wild birds commonly found on California dairies.

Design—Prospective study.

Animals—7 selected species of birds were captured on 9 dairies in Kings and Tulare counties, California.

Procedure—Birds were captured (using traps and nets) and euthanatized, and the entire gastrointestinal tract was removed. Contents of the gastrointestinal tract were subjected to culture for Salmonella spp.

Results—892 birds were captured, and Salmonella spp were isolated from 22 birds. The prevalence by dairy ranged from 0.7 to 16.7%, whereas the prevalence by bird species ranged from 1.2 to 3.2%. Cowbirds and English sparrows had the highest prevalence of Salmonella organisms. Five serotypes of Salmonella organisms were isolated, including Meleagridis, Montevideo, Muenster, Typhimurium, and an untyped serotype.

Conclusions and Clinical Relevance—On the basis of our findings, birds that commonly inhabit California dairies harbor Salmonella organisms. However, because of the low prevalence of Salmonella organisms in birds and the Salmonella serotypes isolated, birds are not important reservoirs of Salmonella organisms on California dairies. (J Am Vet Med Assoc 2002;220:359–362)

Full access
in Journal of the American Veterinary Medical Association