Mauricio J. Giuliodori

Metritis in dairy cows: Risk factors and reproductive performance

The objectives of this study were to assess the risk factors for metritis, its effects on milk yield and on reproductive performance, and the efficacy of ceftiofur therapy in Holstein dairy cows. Cows (n=303) from a commercial dairy herd in Argentina were studied. Cows were scored for body condition, and blood samples were collected on d -14, 7, 21, 31, 41, and 50 relative to parturition. Cows having a watery, purulent, or brown, and fetid vaginal discharge (VD) and rectal temperature ≤ 39.2°C were diagnosed as having clinical metritis, and those having a similar VD and rectal temperature >39.2°C were diagnosed as having puerperal metritis. Both clinical and puerperal metritis cows were randomly assigned to control (no treatment) or ceftiofur group (2.2mg/kg×3 consecutive days). Cure was declared if clear VD was observed at 21 d in milk (DIM). Blood samples were analyzed for nonesterified fatty acids, β-hydroxybutyrate, and blood urea nitrogen using commercial kits, and for insulin-like growth factor-1, insulin, and leptin by RIA. Data were analyzed with PROC MIXED, GENMOD, PHREG, and LIFETEST from SAS (SAS Institute Inc., Cary, NC). The risk for metritis increased with dystocia, retained fetal membranes, and dead calf [AOR (adjusted odds ratio)=2.58, 95% CI: 1.189-5.559], and as prepartum nonesterified fatty acids levels increased (AOR=1.001, 95% CI: 0.999-1.002). Conversely, risk decreased as prepartum insulin-like growth factor-1 increased (AOR=0.65, 95% CI: 0.349-1.219). Cows having either clinical or puerperal metritis produced less milk by 90 DIM than did healthy cows (2,236 ± 172 vs. 2,367 ± 77 vs. 2,647 ± 82 kg, respectively). Cows with puerperal metritis had lower risk for pregnancy by 100 DIM (AOR=0.189, 95% CI: 0.070-0.479) and a lower hazard rate for pregnancy by 150 DIM (hazard rate: 0.753, 95% CI: 0.621-0.911), and took longer to get pregnant (129 vs. 111 vs. 109 d, for puerperal metritis, clinical metritis, and healthy cows, respectively). Ceftiofur treatment was not associated with cure rate or milk yield but was related to increased risk for pregnancy at timed artificial insemination (AOR=2.688, 95% CI: 0.687-10.832), and for lower risk of reproductive cull (AOR=0.121, 95% CI: 0.014-1.066). In conclusion, abnormal calving and negative energy balance are associated with increased risk for metritis. Metritis, especially puerperal metritis, correlates with reduced milk production and poor reproductive performance. Finally, the likelihood for having a normal VD (indicative of cure) increased 2.6% for every day of increase in postpartum time and was 2 times higher for cows with clinical metritis than for those with puerperal metritis.

The relationship between endometrial cytology during estrous cycle and cutoff points for the diagnosis of subclinical endometritis in grazing dairy cows

The objectives of this study were to assess the effect of the stage of estrous cycle on the percentage of endometrial polymorphonuclear cells (PMN) obtained by cytobrush to determine cutoff values for the diagnosis of subclinical endometritis under pastoral conditions, to measure the prevalence of subclinical endometritis 21 to 62d in milk (DIM), and to evaluate the effect of subclinical endometritis on reproductive performance in grazing dairy cows. The first experiment was conducted on a commercial dairy farm in Buenos Aires province (Argentina), where 17 postpartum cyclic dairy cows without clinical endometritis were selected and synchronized by Ovsynch protocol. Endometrial cytology (cytobrush technique) and blood (tail vessels) samples were obtained on d0, 4, 11, and 18 of the estrous cycle (corresponding to estrus, metestrus, diestrus, and proestrus, respectively) and used for measuring percentage of PMN and P4 concentration, respectively. The percentage of PMN was determined 3times by blinded count by 2 operators. Data were analyzed with PROC MIXED, PROC GENMOD, and PROC FREQ from SAS 9.1. The percentage of PMN did not vary with the stage of the estrous cycle. In addition, PMN counts were below any of the reported thresholds in this study (4%) for most of the cows. Therefore, the risk for false positive test results as a consequence of physiological changes in the counts of PMN during estrous cycle is low. The second experiment was conducted on 4 commercial dairy farms in Buenos Aires province (Argentina), where lactating Holstein dairy cows (n=418) 21 to 62 DIM without clinical endometritis were studied. Samples of endometrial cytology were collected with the cytobrush technique. Data were analyzed with receiver operator characteristic curves with Sigmaplot 10.0, and with PROC GLIMMIX, PROC PHREG, and PROC LIFETEST from SAS 9.1. Cutoff values for the diagnosis of subclinical endometritis in grazing dairy cows are 8% PMN for 21 to 33 DIM, 6% PMN for 34 to 47 DIM, 4% PMN for 48 to 62 DIM, and overall 5% PMN for 21 to 62 DIM; the prevalence of subclinical endometritis 21 to 62 DIM was 17%. Finally, subclinical endometritis diagnosed at 21 to 62 DIM decreases the hazard for pregnancy (hazard ratio=0.668; 95% confidence interval=0.492-0.909) and increases the calving to conception interval by d30 compared with normal cows (median 95% confidence interval=133 vs. 93, respectively).

Endometrial cytology, biopsy, and bacteriology for the diagnosis of subclinical endometritis in grazing dairy cows

The objectives of this study were to assess the agreement between endometrial cytology and uterine biopsy for the diagnosis of subclinical endometritis (SEND) in grazing dairy cows, the interobserver agreement of the biopsys readings, and the bacterial population isolated from the uterus of cows having SEND. In experiment 1, lactating Holstein cows (n=44) 31 to 59 d in milk (DIM) at sampling were enrolled. Clinical endometritis was diagnosed by direct evaluation of vaginal discharge and SEND by endometrial cytology evaluation. Two hundred cells per smear were counted to determine the percentage of polymorphonuclear neutrophilic leukocytes (PMNL). Cut-off values used were ≥8% PMNL at ≤33 DIM, ≥6% PMNL at 34 to 47 DIM, and ≥4% PMNL at ≥48 DIM. Biopsies were assessed blindly by 2 observers who categorized them into 4 groups according to their inflammatory changes: none, minimal, moderate, and severe inflammatory changes. Data were analyzed using the kappa coefficient and logistic regression. In experiment 2, lactating Holstein cows (n=60) 21 to 62 DIM were enrolled. Clinical endometritis and SEND were diagnosed as previously described. Samples were cultured for aerobic and anaerobic bacteria by routine methods of bacteriological testing. Data were analyzed with logistic regression. In experiment 1, little agreement was observed between cytology and biopsy outputs (kappa=0.151), and strong agreement between the 2 operators (kappa=0.854). The likelihood of having a normal biopsy (no inflammatory change) was greater for healthy cows than for those having SEND (odds ratio=13.145). The probability for getting normal uterine tissue decreased 2.1% for every increasing percentage point in PMNL. In experiment 2, no bacteria were isolated from cows with SEND, coagulase-negative staphylococci were commonly isolated from healthy cows, and Trueperella pyogenes was frequently isolated from cows with clinical endometritis. The likelihood of isolating T. pyogenes from uterine samples increased with the percentage of PMNL (odds ratio=1.100). In conclusion, biopsy showed low agreement with cytology for the diagnosis of SEND. Nevertheless, fertility trials using uterine biopsies to predict pregnancy outcomes are needed to determine its diagnostic usefulness. Finally, bacteriology would not be recommended as a diagnostic tool because no bacteria were isolated from cows with SEND.

Cattle hypocuprosis in Argentina associated with periodically flooded soils

Abstract Although it has been known for a long time that hypocuprosis affects cattle in the province of Buenos Aires (Argentine), mostly during the spring, there has been no attempt to estimate the occurrence of this deficiency. A survey involving more than 200 farms was carried out in five districts of the Salado river basin, where hypocuprosis is endemic. A total of 4750 plasma samples were obtained during 1993 to 1996, and the Cu content was analyzed by atomic absorption spectrophotometry. Fifty-six per cent of cattle population in the five districts was hypocupremic (plasma Cu −1 ), while 14% was severely hypocupremic ( −1 ). The highest incidence was during 1994, when 71% of cattle was hypocupremic and 26% was severely hypocupremic. During the spring a maximum of 37% of cattle was severely hypocupremic, which agrees with previous findings. The causes of hypocuprosis have been defined for the area, as low forage Cu with high S and Fe mainly during the autumn. A positive association between the occurrence of hypocuprosis and excesses of rainfall was found, that explain the seasonal pattern of hypocuprosis and the influence of floodings on hypocuprosis.

Student interaction characteristics during collaborative group testing

We used collaborative testing in a veterinary physiology course (65 students) to answer the following questions: 1) do students with individual correct responses or students with individual incorrect responses change their answers during group testing? and 2) do high-performing students make the decisions, that is, are low-performing students carried by high-performing peers? To address these questions, students first completed the exam in the traditional format as individuals. After completing the exam as individuals, students completed the same exam in groups of two. Finally, the same questions were discussed by the instructor and students (instructor feedback). We found that students with individual incorrect responses changed their answers during group testing more often than students with individual correct responses (odds ratio: 7.58, P < 0.01). Furthermore, student feedback was more beneficial when group members had different individual answers than when they had same individual answers (P < 0.05). In addition, when group members had different individual answers, more answers were changed to correct responses than to incorrect responses (77% vs. 23%, P < 0.01). It was more important to have the correct answer than to be the high-performing student, because the student with the correct response (being either the high- or low-performing student) generally prevailed ( approximately 80% of the time, P = 0.5). Finally, the positive effects of group testing (77% of total effects, P < 0.05) were due to students who changed their individual answer to the correct response after discussion with peers with the correct response and also with the incorrect individual response.

Clinical endometritis in an Argentinean herd of dairy cows: Risk factors and reproductive efficiency

The objectives of this study were to assess the clinical and metabolic risk factors for clinical endometritis, the likelihood for having a normal vaginal discharge during postpartum, and the effects of endometritis on milk yield, reproductive efficiency, and metabolic status in Holstein cows. The study was conducted in a commercial dairy herd (Cordoba, Argentina) where 303 Holstein cows were enrolled. Cows were body condition scored (1 to 5) and tail bled on -14, 7, 21, 31, 41, and 50 d relative to parturition. Cows having a vaginal discharge with presence of pus between 21 and 41 d postpartum (dpp) were diagnosed as having clinical endometritis. Plasma blood samples were analyzed for nonesterified fatty acids (NEFA), β-hydroxybutyrate (BHBA), and blood urea nitrogen using commercial kits and insulin-like growth factor 1, insulin, and leptin by RIA. Data were analyzed with PROC MIXED, PROC GENMOD, and PROC PHREG of SAS (SAS Institute Inc., Cary, NC). Abnormal calving and puerperal metritis increased the risk for endometritis [adjusted odds ratio (AOR)=2.21 for both]. High prepartum NEFA and high postpartum BHBA increased the risk for endometritis (AOR=1.003 and 1.001, respectively), whereas high prepartum blood urea nitrogen reduced it (AOR=0.853). Cut-offs of 456.6 μM NEFA and 402.5 μM BHBA had sensitivities of 0.69 and 0.58, and specificities of 0.88 and 0.86, respectively. The likelihood for having normal vaginal discharge increased with time (∼1% × dpp) and with normal calving. Cows with endometritis had higher milk yield than normal herdmates (27.8±0.9 vs. 25.7±0.4 kg/d), lower risk for pregnancy by 100 dpp (AOR=0.10), higher nonpregnancy risk by 200 dpp (AOR=2.87), and higher risk for culling than normal cows (AOR=2.28). Cows with endometritis had a lower hazard rate (0.44) for pregnancy and had approximately 70 d longer calving-to-conception intervals. Finally, endometritis had no effect on metabolic hormones. In conclusion, the risk for clinical endometritis increases with abnormal calving and puerperal metritis, as prepartum NEFA and postpartum BHBA concentrations increase. Prepartum NEFA and postpartum BHBA could be useful for the prediction of endometritis. Last, clinical endometritis has detrimental effects on reproductive efficiency, as affected cows take longer to get pregnant and are at higher risk for culling.

Mortes súbitas em bovinos associadas à carência de cobre

An outbreak of sudden death was observed in cattle in southern Brazil. No significant gross or microscopic lesions were found in 10 cattle at post-mortem examination. To test if the sudden deaths were caused by a toxic plant, 13 weeds were collected and given to rabbits at a total of 440 to 600 g per kg body weight within 7 days. Results were negative. Mean copper levels of the liver in 10 cattle were very low (3.6±1.6 ppm-dry matter) suggesting Cu deficiency as the cause of the disease. Five samples of pasture collected during the outbreak had normal levels of Cu (8.4±0.8 ppm-d.m.) and S (0.2%±0.03-d.m.), but high levels of Fe (522±122 ppm-d.m.). One group of 10 heifers was supplemented with Cu subcutaneously. This group and a similar control group were maintained in the same area where the outbreak occurred. Serum levels of Cu, S, Fe, Mo and ceruloplasmin were determined bimonthly in both groups during one year. Mean serum levels of Cu (1.76±1.06 to 10.34±3.1 µmol/l for the control group and 3.86±1.53 to 10.61±1.34 µmol/l for the treated group) and ceruloplasmin (6.59±3.93 to 18.61±4.14 mg/l for the control group and 10.31±5.48 to 32.49±6.05 mg/l for the treated group) were significantly higher in the supplemented group (P=0.0046 for Cu and P=0.0001 for ceruloplasmin), but they were below normal levels in most samples of both groups. Serum levels of Cu and ceruloplasmin were correlated (r=0.67; P=00.5). In both groups serum levels of Fe (40.09±5.25 to 78.48±28.23 µmol/l) were higher than normal levels. Samples of forage were collected bimonthly for determination of Cu, Mo, S, Fe and protein in 7 points of the paddock where the outbreak occurred. Levels of Cu (1.36±0.56 to 4.76±1.15 ppm-d.m.) were below the normal ranges. The concentration of Mo (0.17±0.06 to 0.96±0.47 ppm-d.m.) was within normal ranges. Levels of S (0.21±0.04% to 0.5±0.17%) and Fe (172.92±62.64 to 437.24±205.44 ppm-d.m.) were occasionally within toxic level. Levels of protein varied from 7.77±2.6% to 13.16±3.02%. Six samples of water and six of submersed pastures were collected at the end of the experiment when the paddock was flooded. High levels of iron (169.23±83.49 ppm-d.m. ) and S (0.06±0.03%) were found in the water. Levels of Fe and S in the submerse pasture were of 469.3±218.28 ppm and 0.19±0.05%, respectively. The results obtained suggest that the sudden deaths are due to Cu deficiency. Three factors seem to be responsible for the Cu deficiency: 1) high levels of iron in pastures and water; 2) occasionally low levels of copper in the pastures; and 3) the ingestion of S above the requirements due to the levels occasionally high in pastures and high in water. The outbreak reported is similar to other outbreaks of sudden deaths associated with low liver copper previously reported during winter in the same region of southern Brazil. This area is characterized by acid sandy soils with frequent flooding during this season. In periodically flooded acid soils iron is solubilized and absorbed by the plants, decreasing the Cu content and increasing the Fe content of forage. This seems to be the main reason for Cu deficiency in the region.

Hooke's law: applications of a recurring principle

Students generally approach topics in physiology as a series of unrelated phenomena that share few underlying principles. However, if students recognized that the same underlying principles can be used to explain many physiological phenomena, they may gain a more unified understanding of physiological systems. To address this concern, we developed a simple, inexpensive, and easy to build model to demonstrate the underlying principles regarding Starlings Law of the Heart as well as lung and arterial elastic recoil. A model was chosen because models significantly enhance student understanding. Working with models also encourages research-oriented learning and helps our students understand complex ideas. Students are drawn into discussion by the power of learning that is associated with manipulating and thinking about objects. Recognizing that the same underlying principles can be used to explain many physiological phenomena may help students gain a more complete understanding of physiological systems.

Characterization of cattle copper deficiency in the Magdalena district

Abstract A field survey involving 13 farms was carried out during the spring of 1994 in the Magdalena district to elucidate the causes of cattle hypocuprosis, that has been previously detected as a widespread condition in the area. From each farm, 30 blood samples and representative forage samples were obtained. Liver samples (N: 40) were obtained at a local slaughterhouse. Plasma and liver Cu, and forage Cu, Fe, Mo and S contents were analyzed. Plasma Cu concentrations were below 60 μg/dl in 78.6%, 37.6% and 61.9% of samples from calves, heifers and cows, respectively, in a total of 390 samples. Liver Cu concentration was below 75 ppm DM in 77.5% of the samples. The forage Cu concentration in 44 samples averaged 6.0 ppm DM, and was below the recommended level of 8 ppm in 84% of the samples. Molybdenum and S concentrations averaged 0.65 ppm DM and 0.28% DM, respectively. It is concluded that the widespread hypocuprosis develops as a simple deficiency, complicated by the high levels of S in the forages. This contrasts the Mo toxicity problems reported for other districts within the same basin.

Dynamics of bacteriologic and cytologic changes in the uterus of postpartum dairy cows

The objectives of this study were to characterize clinical, intrauterine, bacteriologic and cytologic changes during the first month after parturition in healthy dairy cows and in cows with subclinical endometritis (SE) or clinical endometritis (CE). Furthermore, risk factors related to clinical bacteriologic and cytologic findings were determined. A total of 170 calvings were enrolled, and intrauterine samples were collected on Days 0, 3, 9, 15, 21, and 28 postpartum using the cytobrush technique. The presence of Escherichia coli and Trueperella pyogenes was determined by Fourier transform infrared spectroscopy. The cows were categorized according to their uterine health status (UHS) on Day 21 as healthy (clear or absent vaginal discharge and <5% polymorphonuclear cells [PMN] in the cytologic sample), SE (clear or absent vaginal discharge and ≥5% PMN), or CE (vaginal mucus containing any signs of pus). The prevalence of SE and CE on Day 21 was 27.9% and 58.4%, respectively. Generally, samples from cows with SE and CE showed a greater bacterial growth density (BGD) than those from healthy cows. The BGD tended to be affected by the interaction of time by UHS (P = 0.057). Differences between healthy, SE, and CE cows were found from Day 3 to the last sampling day. Furthermore, the percentage of PMN differed between healthy, SE, and CE cows and was affected by time in a cubic way (decrease/increase/decrease). Overall, E coli was found in 25.4% of the samples, and T pyogenes was identified in 30.2% of the samples. The risk for CE was increased by BGD and the presence of T pyogenes. Conversely, the presence of E coli had no effect on the risk of CE or the risk of SE. The risk for an infection with T pyogenes was greater in the first-parity cows and in cows with assisted calving. In conclusion, changes in BGD and proportion of PMN varied with the UHS (healthy, SE, and CE), which was affected by the presence of T pyogenes but not E coli.