Using chitosan microparticles to treat metritis in lactating dairy cows

摘要

The main objective of this study was to evaluatethe efficacy of intrauterine administration of chitosanmicroparticles (CM) in curing metritis in dairy cows.A secondary objective was to evaluate the effects ofmetritis treatments on milk yield, survival, and reproductiveperformance. Cows with a fetid, watery,red-brownish vaginal discharge were diagnosed withmetritis. Holstein cows (n = 826) with metritis from3 dairies located in northern Florida were blocked byparity (primiparous or multiparous) and, within eachblock, randomly assigned to one of 3 treatments: CM (n= 276) = intrauterine infusion of 24 g of CM dissolvedin 40 mL of sterile distilled water at the time of metritisdiagnosis (d 0), 2 (d 2), and 4 (d 4) d later; ceftiofur(CEF; n = 275) = subcutaneous injection of 6.6 mg/kg ceftiofur crystalline-free acid in the base of the earat d 0 and d 3; Control (CON; n = 275) = no treatmentapplied at metritis diagnosis. All groups couldreceive escape therapy if condition worsened. Cure wasconsidered when vaginal discharge became mucoid andnot fetid. A group of nonmetritic (NMET; n = 2,436)cows was used for comparison. Data were analyzed bygeneralized linear mixed and Cox’s proportional hazardmodels. Cows in CM and CON had lesser risk of metritiscure on d 12 than cows in CEF (58.6 ± 5.0 vs.61.9 ± 4.9% vs. 77.9 ± 3.9, respectively). The proportionof cows culled within 60 days in milk (DIM) wasgreater for cows in CM than for cows in CEF and CON(21.5 ± 2.7 vs. 9.7 ± 1.9 vs. 11.3 ± 2.0%, respectively).Treatment did not affect rectal temperature or plasmanonesterified fatty acids, β-hydroxybutyrate, and haptoglobinconcentrations. Milk yield in the first 60 DIMdiffered for all treatments, and it was lowest for CM(35.8 ± 0.3 kg/d), followed by CON (36.8 ± 0.3 kg/d)and CEF (37.9 ± 0.3 kg/d). The hazard of pregnancyup to 300 DIM was lesser for CM than CEF (hazardratio = 0.62; 95% CI: 0.50–0.76), for CM than CON(hazard ratio = 0.77; 95% CI: 0.62–0.95) and for CONthan CEF (hazard ratio = 0.80; 95% CI: 0.65–0.99).Culling was greater, and milk yield and fertility werelesser for CEF than NMET. In summary, CM did notimprove the cure of metritis, and was detrimental tomilk yield, survival, and fertility compared with CON.In contrast, CEF increased the cure of metritis, milkyield, and fertility compared with CM and CON. Finally,the negative effects of metritis on milk yield cullingand fertility could not be completely reversed by CEF.