Associations of somatic cell count with milk yield and reproductive performance in grazing dairy cows.

Poor udder health status can have a detrimental effect on milk yield and reproductive performance, leading to reductions in the dairy farm profit. The objective of this retrospective longitudinal study was to assess the associations of somatic cell count (SCC) with daily milk yield and reproductive performance. A database with 1,930,376 lactations from 867 Argentinean grazing dairy herds records collected for 14 years was used. The association of the evolution of SCC (healthy vs. new case vs. cured vs. chronic; with 150,000 SCC/mL as threshold) and of the severity of SCC [mild (150,000--400,000 SCC/mL) vs. moderate (400,000-1,000,000 SCC/mL) vs. severe (>1,000,000 SCC/mL)] with the odds for conception were estimated. Finally, the associations of the linear score of SCC (LS-SCC) with daily milk yield were estimated depending on parity and milk production quartile. The odds ratios (CI 95%) for conception at first service were 0.921 (0.902-0.941), 0.866 (0.848-0.884), and 0.842 (0.826-0.859) for the new case, cured, and chronic cows compared with healthy cows, respectively. Also, the odds ratios (CI 95%) for conception were 0.902 (0.881-0.925), 0.837 (0.808-0.866) and 0.709 (0.683-0.736) for mild, moderate and severe cases compared with healthy cows, respectively. An increase of one point of LS-SCC was associated with decreases of 0.349, 0.539, and 0.676 kg in daily milk yield for first-, second-, and third-lactation cows, respectively. In conclusion, SCC is negatively associated with the risk for conception and with daily milk yield in grazing dairy cows. This negative relationship with conception is higher when SCC increase occurs after the service date and it is influenced by severity of mastitis, and in the case of milk yield, the negative association is influenced by parity, milk production quartile, and severity of mastitis.

Detection of nonpregnant cows and potential embryo losses by color Doppler ultrasound and interferon-stimulated gene expression in grazing dairy cows.

Many studies have been conducted to estimate pregnancy losses between 19 and 34 d after artificial insemination (AI) in dairy cows managed under confinement-based systems, but few studies have examined embryo mortality during this interval in dairy cows managed under gazing systems. The objectives of this prospective cohort study were (1) to assess the diagnostic value of the corpus luteum (CL) blood perfusion (BP) evaluation by Doppler ultrasound (US) to detect nonpregnant cows at 19 to 20 d post-AI, and (2) to assess the rate of potential embryo mortality between 19 to 34 d post-AI. The CL-BP of all cows included in the study (n = 131) was examined on farm by power and color mode of Doppler US and later using an image processing software by a second evaluator. The endometrium thickness and echotexture were evaluated by B-mode US at the same visit to assess if the nonpregnancy diagnosis could be improved at 19 to 20 d post-AI by this additional diagnostic tool. Blood samples were obtained at 19 to 20 d post-AI for progesterone (P4) measurement by chemiluminescence and to determine the mRNA expression of ISG by real-time PCR. Pregnancy diagnosis based on embryo visualization was performed at 33 to 34 d post-AI by US B-mode. In parallel interpretation, ISG15 and MX2 mRNA expression in leukocytes [sensitivity (Se), 100%] were regarded as suitable biomarkers for early pregnancy and were selected for molecular characterization of pregnancy at 19 to 20 d post-AI. At 19 to 20 d post-AI, 61.1% of the cows had positive CL-BP by Doppler US (Se, 98.0%), 62.7% had ISG mRNA expression in leukocytes over the cutoff point (Se, 95.7%), and 50.8% were positive, based on the combination of ISG mRNA expression, CL-BP by Doppler US, and P4 concentration (Se, 100%), and were considered as possible pregnant. At 33 to 34 d, the pregnancy rate was 37.4% diagnosed by the B-mode US. Based on the expression of the selected biomarkers in cows with active CL, we found that 28.1% of the cows could have potentially lost their pregnancy between 19 and 34 d post-AI. The Doppler US color mode showed similar accuracy and a higher negative predictive value than the genes selected as biomarkers. The additional B-mode ultrasound evaluation of the uterine stratum vasculare and the endometrium thickness improved the diagnostic accuracy. Therefore, assessing the CL-BP by Doppler US allowed early detection of nonpregnant cows at 19 to 20 d post-AI. The combination of early CL-BP by Doppler US (d 19 to 20) with early embryo detection by B-mode US (d 33-34) could be used to facilitate earlier rebreeding of dairy cows.

Effect of milk production on reproductive performance in dairy herds.

The objective of the present study was to assess the relationship between individual cow milk yield and fertility, accounting for the contextual effect of the herd. A data set including 657,968 lactations from 677 dairy herds in Argentina from 2001 to 2012 was used. The odds of pregnancy by 100 d in milk (DIM) were assessed by a multilevel logistic model (with cow as the first and herd as the second hierarchical level), and time to pregnancy was assessed by a proportional hazards regression model. Multilevel logistic models included the fixed effects of milk yield by 80 DIM, parity, year, and calving season at cow level and quartiles of herd milk yield by 80 DIM as a contextual effect. The proportional hazards model included the effect of daily cow-level milk yield as time-dependent variable, with milk yield at herd level as the stratification variable. Cows producing 1 standard deviation over the mean milk yield of their herd had 1.3 percentage point lower pregnancy by 100 DIM (from 31.4 to 30.1%; odds ratio = 0.942) when in herds in the top quartile of milk yield, whereas they increased 0.5 percentage points (from 27.9 to 28.4%) when in herds in the lowest quartile of milk yield. Only 4% of the observed variation in pregnancy by 100 DIM was explained by the random effect of the herd. Similarly, cows producing 1 standard deviation (8 kg/d) greater than the herd mean daily milk had 1.3% lower hazard of pregnancy (hazard ratio = 0.987) at 63 DIM in herds in the top quartile of milk yield, whereas they had 14.8% higher hazard (hazard ratio = 1.148) in herds in the lowest quartile of milk yield. The magnitude of the negative association between the cow's daily milk yield and the hazard of pregnancy increased with DIM. In conclusion, the relationship between milk yield and reproductive performance is statistically significant, but the effect size is practically small and is modulated by herd production level.

Vaginal isolation of beta-haemolytic Streptococcus from bitches with and without neonatal deaths in the litters.

The aim of the study was to identify beta-haemolytic streptococci in the vagina of bitches who had delivered healthy litters and bitches who had delivered litters in which neonatal deaths occurred. Fifty-one bitches divided into two groups were used. Group 1 (G1) included 28 bitches that had delivered healthy litters and group 2 (G2) included 23 bitches that had delivered puppies who died in the neonatal period. Two vaginal samples were taken, one in proestrus and the other at the end of gestation (EG). Beta-haemolytic Streptococcus (BS) was isolated from 16 bitches (57%) in G1 and from 21 bitches (91%) in G2. The bacteriological cultures, serological tests (Streptex® ) and PCR assay allowed identification of Streptococcus canis and Streptococcus dysgalactiae in G1 and G2. Ultramicroscopic studies allowed the observation of M Protein and capsules in strains of S. dysgalactiae and S. canis in G1 and G2. The S. canis strains isolated from G2 showed thicker capsules than S. canis strains isolated from G1 (234 ± 24.2 vs 151.23 ± 28.93 nm; p < .001.). No differences were observed in capsule thickness between strains of S. dysgalactiae isolated from G1 and G2 (210 ± 13.54 vs 211.66 ± 19.67 nm; p > .70). All strains of beta-haemolytic Streptococcus isolated were penicillin sensitive. Penicillin was administered from EG to 5 days post-partum in 10 G2 females with isolation of BS (G2A). Saline solution was administered in eleven G2 females with isolation of BS (G2B). Ninety per cent of the puppies survived in G2A and 25% survived in G2B. Our results suggest BS is involved in canine neonatal deaths.

Purulent vaginal discharge in grazing dairy cows: Risk factors, reproductive performance, and prostaglandin F2α treatment.

The objectives of this study were to assess the association of a 4-point scale of vaginal discharge score (VDS) with time to pregnancy to define criteria for a practical case of purulent vaginal discharge (PVD) in dairy cows, to test the risk factors for PVD, and, finally, the effect of a dose of PGF2α on cure and reproductive performance. In experiment 1, grazing Holstein cows (n = 2,414) had their vaginal discharge scored at ∼32 d in milk (DIM) on a 4-point scale, the effect of VDS on the hazard of pregnancy by 300 DIM was then assessed to derive a case definition of PVD. Risk factors for PVD and self-cure were also assessed. In experiment 2, grazing Holstein cows (n = 6,326) from 5 herds were checked for PVD at ∼30 DIM. Cows with PVD were assigned to receive one dose of 500 µg of PGF2α analog (Cloprostenol; Ciclase, Syntex SA, Buenos Aires, Argentina) per cow (odd ear tag number) or to remain untreated (even tag number). Cure was declared if cows presented clear normal vaginal discharge (VDS-0) at visit 2 (∼62 DIM). Data were analyzed with Cox's regression and mixed logistic models. In experiment 1, cows with VDS ≥1 had lower hazard of pregnancy and longer calving to pregnancy interval than cows with VDS-0. This finding was not affected by the time at which the diagnosis was performed. Therefore, a cow ≥21 DIM and having VDS ≥1 was used to define a case of PVD. The odds of PVD were greater in primiparous cows compared with multiparous, in cows with abnormal calving compared with those with normal calving, and in those losing BCS peripartum. In experiment 2, PGF2α treatment tended to slightly increase the hazard of pregnancy (adjusted hazard ratio = 1.13). Conversely, PGF2α had no effect on the odds of cure of PVD [adjusted odds ratio (AOR) = 1.19], pregnancy at first service (AOR = 1.03), or pregnancy by 100 DIM (AOR = 0.89) or 200 DIM (AOR = 1.27). In conclusion, cows with VDS ≥1 can be considered to have PVD because of their lower hazard of pregnancy and longer calving to pregnancy interval (up to 48 d). Important risk factors are parity, calving, and body condition score loss peripartum. Optimal time of diagnosis is ≥28 to 35 DIM because cows experience a high self-cure rate. Self-cure is also affected by parity, prepartum BCS, and VDS. Finally, as treatment with one dose of PGF2α had a small effect on the hazard of pregnancy and no effect on clinical cure, its therapeutic use in grazing dairy cows with PVD is not recommended.

Short communication: Repeat breeder cows with fluid in the uterine lumen had poorer fertility.

The objective of the present study was to test the association between the presence of fluid in uterine lumen and the fertility of repeat breeder cows (RBC). Grazing Holstein cows that were clinically normal and were not pregnant after at least 3 consecutive inseminations were defined as RBC and included in the study (n = 358). A cut-point ≥2 mm of uterine lumen visible by ultrasonography was used as indicative of the presence of fluid in the uterus. The effect of this fluid on the fertility of RBC was assessed by mixed logistic regression. Twenty percent of the RBC had ≥2 mm of fluid in their uterus, and this finding was associated with a marked reduction in the odds of conception (odds ratio = 0.46). Additional intrauterine sampling revealed that 24.0% of RBC showed signs of subclinical endometritis [≥5% neutrophils in endometrial cytology (SCE)]. However, we found no agreement between the finding of uterine fluid and the diagnosis of SCE (kappa coefficient = 0.03, 95% confidence interval = -0.07 to 0.14). In conclusion, the presence of fluid (≥2 mm) in uterine lumen, detected by ultrasonography, was associated with lower fertility in RBC, but was not related to the diagnosis of SCE. Thus, ultrasonographic evaluation is an important tool to assist in assessment of RBC.

Application of a bacteriological on-farm test to reduce antimicrobial usage in dairy cows with purulent vaginal discharge.

The objective of this study was to assess the effect of a selective antibiotic treatment strategy based on a quick bacteriological on-farm test (Petrifilm, 3M Corp., St. Paul, MN) compared with the conventional antibiotic treatment of all cows having clinical endometritis (CE) defined by the presence of purulent vaginal discharge on both clinical cure rate and reproductive performance. The study was simultaneously conducted with dairy cows reared under a highly supplemented rotational grazing system in Argentina and in a freestall system in Slovakia. Cows having an abnormal vaginal discharge (VD, indicative of clinical endometritis) on 21 to 35 d in milk (DIM) were randomly allocated to 1 of 2 study groups: selective treatment (ST) or conventional treatment (CT). All cows in the CT group (n = 174) received a single intrauterine administration of 500 mg of cephapirin. In the ST group (n = 178), treatment decision was made according to the results of the bacteriological on-farm test. For this test, we collected intrauterine samples with the cytobrush technique and stroke the brushes onto 2 different Petrifilm plates, one for aerobic count and another for Enterobacteriaceae count, incubated the plates, and counted the number of colonies after 24 h. Positive cows (≥5 colonies in one or both plates) received a single intrauterine treatment with 500 mg of cephapirin, whereas negative cows (<5 colonies) remained untreated. Clinical cure rate was assessed by direct vaginal inspection at 14 d after treatment (VD-0). The odds for conception at first artificial insemination, artificial insemination by 80 DIM, pregnancy by 100 DIM, and for nonpregnancy by 200 DIM were estimated with mixed logistic regression models. The hazard of conception was also assessed with proportional hazard regression model. The selective antibiotic treatment strategy based on the outcome of Petrifilm test reduced the number of required treatments (57%) and maintained similar efficacy in terms of clinical cure and reproductive performance as the conventional antibiotic treatment of all endometritic cows.

Prostaglandin synthesis enzymes' gene transcription in bitches with endometritis.

Endometritis is a major cause of infertility in many domestic species. However, until now the pathogenesis of the endometritis in the bitch is unclear. The aim of this study was to evaluate the gene transcription pattern of prostaglandin (PG) synthesis enzymes (cyclooxygenase [COX2], PTGES-1 and PGFS) in the endometrium of bitches with or without endometritis. Thirty mixed breed bitches in dioestrus, aged between 1 and 5 years, and weighing between 10 and 30 kg were used. After ovariohysterectomy (OVX), uterine biopsy samples were collected from the middle part of both horns. Then, endometrial epithelium was collected using the cytobrush method and mRNA analysis was performed by real-time RT-PCR. Data were analysed with Kruskal-Wallis anova using the sas® software. Uterine condition was identified by endometrial biopsies (normal endometria [n = 11; NE], acute endometritis [n = 10; AE] and chronic endometritis [n = 9; CE]). The COX2, PTGES-1 and PGFS/AKR1C3 mRNA expression in bitches with and without endometritis was similar. Except for PGFS/AKR1C3, gene transcription of COX2 and PTGES-1 was significantly increased in AE compared with CE. In addition, COX2 gene transcription was significantly increased in AE compared with NE. In contrast, no differences were found for COX2, PTGES-1 and PGFS/AKR1C3 mRNA expression in the samples of NE compared with CE.

Prolactin, Androstenedione and IGF1 Serum Concentrations During Induced Follicular Growth by eCG Administration in the Bitch.

The oestrus cycle in the domestic bitch, a monoestrous species, differs considerably from that of other veterinary domestic animals species. In the bitch the combined use of eCG and hCG is effective to induce oestrus predictably and safely (Stornelli et al., Theriogenology, 78, 2012 and 1056). Although several studies were done to describe the hormonal changes during the canine oestrus cycle, to our knowledge none was done to describe the hormonal changes during induced follicular growth after the administration of eCG. The aim of this work was to study prolactin (PRL), insulin-like growth factor (IGF1) and androstenedione (ANDR) serum concentrations during follicular growth induced by a single dose of eCG administered to late anoestrous bitches. PRL and ANDR concentrations were lower before than after eCG TRT (before eCG vs pro-oestrus, oestrus and dioestrus; 4.3 ± 1.8 ng/ml vs 6.5 ± 1.6 ng/ml, p < 0.05; 0.08 ± 0.2 ng/ml vs 0.42 ± 0.16 ng/ml, p < 0.05). Conversely, IGF1 concentrations were similar before and after eCG TRT (286.0 ng/ml ±32.2, p > 0.53). Additionally, PRL concentrations were similar before oestrus compared to during oestrus and dioestrus (6.9 ± 1.7 ng/ml, p > 0.19). Furthermore, IGF1 concentrations were higher before and during oestrus compared to first day of dioestrus (286.1 ± 29.8vs 200.4 ± 29.2 ng/ml, p < 0.01). On the contrary, ANDR concentrations were lower before and during oestrus compared to first day of diestrum (0.35 ± 0.17 ng/ml and 0.38 ± 0.15 vs 0.68 ± 0.17 ng/ml, p < 0.05). These results show that treatment with a single injection of 50 IU/kg of eCG in late anoestrous bitches successfully induced changes in follicular growth which were paralleled with changes in PRL, IGF1 and ANDR serum concentration similar to those occurring during a normally occurring oestrous cycle. In addition, our results suggest that IGF1 in the bitch could play an important role in ovarian folliculogenesis.

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 biopsy's 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.

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, ß-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).

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), ß-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.

Efficacy of cloprostenol or aglepristone at 21-22 and 35-38 days of gestation for pregnancy termination in queens.

The objective of this study was to evaluate the efficacy of cloprostenol (CLO) or aglepristone (ALI) for pregnancy termination in queens at 21-22 and 35-38 days of gestation. Two experiments (EXP) were carried out to accomplish this aim. Thirty-seven 12- to 14-month-old mixed breed queens were used in a randomized design. At oestrus, queens were housed for mating with a tom, and pregnancy was confirmed by transabdominal ultrasonographic examination (US). On days 21-22 of pregnancy (EXP1) or 35-38 of pregnancy (EXP2), queens were divided into three groups (G). Queens in G1 received ALI (10 mg/kg, sc; EXP1, n = 6; EXP2, n = 6) on two consecutive days. Queens in G2 received CLO (5 µg/kg, sc; EXP1, n = 6; EXP2 = 7) on three consecutive days. Queens in G3 received 1 ml of saline solution (PLA, sc; EXP1, n = 6; EXP2 = 6). After treatment, females were monitored daily by US during for 10 days and weekly until the end of gestation. In EXP1, pregnancy was terminated in (6/6, 100%), (0/6, 0%) and (0/6, 0%), for the ALI, CLO and PLA groups, respectively (p < 0.001). In EXP2, pregnancy was terminated in (6/6, 100%), (1/7, 14%) and (0/6, 0%) for the ALI, CLO and PLA groups, respectively (p < 0.001). In both EXP, after CLO administration, animals vomited and were depressed for 30 min; but no side effects were observed in the animals in the ALI group. In conclusion, the results from this study indicate that three injections of CLO are not effective, but two injections of ALI are effective to induce abortion in queens at 21-22 or 35-38 days of pregnancy.

Effect of natural photoperiod on epididymal sperm quality and testosterone serum concentration in domestic cat (Felis silvestris catus).

The aim of this study was to assess epididymal sperm characteristics and serum testosterone concentration in cats under natural photoperiod. The hypothesis was that natural photoperiod induces seasonal changes in spermatozoal quality and serum testosterone concentration. Mixed breed tomcats (n = 43) that underwent bilateral orchiectomy at a municipal public pet shelter were used in the study. Epididymides were divided into two groups according to time of castration. In Group I, toms were castrated during increasing light (IL; [winter and spring; n = 24]), and group II, during decreasing light (DL; [summer and fall; n = 19]). Only mature toms castrated in the two lasts weeks of each season were included in this study. Sperm samples were obtained by cutting the cauda epididymis in Tris solution and tested for motility (MOT,% motile), velocity (VEL, 0-5), total sperm cells (TS, 10(6) ), acrosome integrity (ACR,% intact; FITC-PSA), plasma membrane integrity (MI,%intact; CFDA-PI) and sperm morphology (SM,% normal). Before orchiectomy, blood samples were taken to measure serum concentrations of testosterone (T2) by a solid-phase RIA. Data were analysed with the mixed procedure of SAS. Toms castrated during IL had higher sperm plasma membrane integrity and better sperm morphology compared to toms castrated during DL (69.0 ± 2.7 vs 60.6 ± 2.1, p < 0.01; 45.9 ± 2.5 vs 35.9 ± 3.4; p < 0.02; respectively) and tended to have higher sperm motility and total number of sperm cells compared to toms castrated during DL (56.3 ± 2.8 vs 47.3 ± 3.7, p < 0.06; 13.8 ± 1.4 vs 10.0 ± 1.8, p < 0.09). However, velocity, acrosome integrity and serum testosterone concentrations were similar between both groups (3.5 ± 0.1 vs 3.4 ± 0.1, p > 0.6; 45.8 ± 3.3 vs 44.0 ± 4.0, p > 0.72; 0.76 ± 0.15 vs 0.59 ± 0.19, p > 0.51; respectively). In conclusion, natural photoperiod induces seasonal changes in sperm quality with a moderate variation in serum testosterone concentrations.

Effect of refractoriness to long photoperiod on sperm production and quality in tomcats.

The aim of this study was to assess whether refractoriness to long photoperiod (LP) could be reversed by subjecting tomcats to a period of short days. Our hypothesis was that photoperiod changes can avoid refractoriness and restore sperm quality and production to that before refractoriness. Tomcats (n = 6) were housed in a conditioned room with LP (12L: 12D) for 45 days of acclimation and then maintained under LP for 18 month. Then, tomcats were changed to a period of decreasing light at a rate of 8 min/day for 1 month. Tomcats stayed for 1 month with short photoperiod (SP; 8L: 16D) and then were switched back to a period of increasing light at a rate of 8 min/day for 1 month. The experiment was completed after tomcats remained in LP for 2 months. Toms were anaesthetized and semen samples were collected by electroejaculation every 2 weeks. Sperm parameters were evaluated in all ejaculates, and data were analysed by anova. Motility, velocity, volume, sperm concentration, total sperm count, viability, acrosome integrity, plasma membrane integrity and sperm morphology were higher during LP compared with a refractory LP (p < 0.01). Likewise, velocity, viability, acrosome integrity, plasma membrane integrity and sperm morphology were higher in a LP compared with a SP (p < 0.05). On the other hand, motility, volume, concentration and total sperm count were similar between LP and SP (p > 0.20).Whereas motility, velocity, viability, acrosome integrity and plasma membrane integrity were similar in a refractory LP compared with SP (p > 0.05), volume, sperm concentration, total sperm count and sperm morphology were lower in a refractory LP compared with SP (p < 0.05). In conclusion, refractoriness and reduced sperm production and quality induced by a prolonged LP of 18 month can be restored after placing tomcats to a SP.

Effect of storage media and storage time on histological and ultrastructural changes in cat epididymal cells.

The aim of this study was to assess the histological and ultrastructural changes in cat epididymides (n = 22) stored at 4 °C in two different media [saline solution (SAL) or tris-egg yolk (TEY)]. Our hypothesis was that epididymides stored in TEY would have delayed epithelial cell autolysis. Four epididymides were fixed and processed immediately, and the remaining 18 epididymides were stored at 4 °C in SAL or TEY for 24, 48 or 72 h. In histological sections, the nuclear features and stereocilia morphology were scored from 0 to 3. Ultrastructurally, nuclear chromatin and stereocilia morphology were scored from 0 to 3. In addition, using transmission electron microscopy nuclear number, nuclear area, mitochondrial number and mitochondrial area were recorded. In the histological study, parameters changed with time and media (p < 0.01). A significant effect of time was observed (p < 0.01), and the morphological changes were greatest when the storage time increased. Morphological changes were higher in SAL compared with TEY (p < 0.01). In the ultrastructural study, nuclear chromatin and stereocilia morphology decreased with time and media as in the histological study (p < 0.01). In addition, nuclear number and nuclear area changed with time (p < 0.004; p < 0.001) but not with media. Conversely, mitochondrial number and mitochondrial area did not change with media or time (p > 0.05). In conclusion, these results show that TEY preserved epididymal epithelial cells better than SAL; this finding could help improve sperm quality of stored epididymides.

Heat stress and sperm production in the domestic cat.

This study aimed to assess 1) the effect of high environmental temperatures on sperm production and 2) the effectiveness of a temperature-humidity index (THI) to predict the degree of thermal stress in a cat model. Semen collection was performed by electroejaculation for 18 mo in 20 tomcats maintained under controlled photoperiod. Still, temperature and humidity were not experimentally manipulated to describe the effect of natural climate conditions on seminal samples. Ejaculates (n = 512) were then grouped according to temperature records of the sampling day and compared by temperature and THI index. Significant lower sperm parameters and increase sperm tail abnormalities were observed during warm environments (temperature and THI). Concentration and total sperm count were the most affected parameters. Environmental temperatures of 28.5 °C with 54% relative humidity (THI = 77.07) and 27.9 °C with 66% humidity (THI = 77.84) were upper thresholds of moderate thermal stress. Moreover, days with relative humidity near 90% led to severe thermal stress with temperatures as low as 26.6 °C (THI = 78.88). The current study demonstrates the detrimental effect of high environmental temperatures on sperm quality in the domestic cat. This effect is observed at lower temperatures when high relative humidity is present. In this sense, the THI was a reliable predictor of the magnitude of thermal stress experienced by cats. Thus, cats from reproductive programs should be maintained under controlled photoperiod cycles with temperatures around 20 °C and humidity around 70% to avoid semen detrimental effects.

Prevalence of clinical endometritis and its impact on reproductive performance in grazing dairy cattle in Argentina.

The objective of this study was to evaluate the prevalence of clinical endometritis and its impact on reproductive performance in grazing dairy cattle in Argentina to compare data with previous reports from herds kept in confinement housing systems. A total of 243 Holstein dairy cows from three commercial dairy farms in Buenos Aires Province (Argentina) were examined for the signs of clinical endometritis 18-38 days postpartum (dpp) by external inspection and manual vaginal examination. Vaginal discharge was scored into the categories VDS 0 (transparent, clear mucus), VDS 1 (mucupurulent discharge), VDS 2 (purulent discharge) and VDS 3 (purulent discharge with fetid odour). Cows diagnosed with VDS 1 to VDS 3 were regarded as affected with clinical endometritis and cows with VDS 0 as free of clinical endometritis. All cows were re-examined 14 days later following the same examination protocol. Prevalence of clinical endometritis 18-38 dpp was 35% and decreased to 18% at re-examination. Cows with no palpable ovarian structures or periparturient disorders were at higher risk for clinical endometritis. Hazard for pregnancy was significantly lower in cows with purulent or fetid odour discharge compared with reference cows with no discharge (HR=0.49; p=0.01), resulting in a lower proportion of cows pregnant by 360 dpp (66% vs 78%). Furthermore, the number of services per pregnancy was higher for cows with clinical endometritis than for cows without clinical endometritis (4.4 vs 3.1; p=0.04). Cows with clinical endometritis were 1.6 times as likely to be culled as cows with no signs of clinical endometritis. In conclusion, the prevalence and the impact of clinical endometritis in a pasture-based, extensive dairy production system in Argentina were similar to previously published data from dairy farms with confinement production systems.

Effect of cat seminal plasma and purified llama ovulation-inducing factor (ß-NGF) on ovarian function in queens.

The present study aimed to determine the effect of cat seminal plasma and purified llama ovulation-inducing factor (ß-NGF) on ovarian activity in queens. Queens (n = 6) were used for all the treatments in a crossover design with an interval time between treatments of three interestrus intervals. Forty-eight hours after the detection of an estrus vaginal cytology, queens were given cat seminal plasma (subcutaneous or intramuscular), purified llama ovulation-inducing factor (15 or 35 µg), hCG (75 UI), saline, or were mated with a male. A total of 192 estrous cycles were observed. Estrus length and serum estradiol concentration were 6 ± 1 days (range 2-10 d) and 38 pg/mL (range 10-75 pg/mL), respectively. Queens mated and given hCG showed higher serum progesterone concentration and longer interestrus interval (47 ± 5 d) than that of controls (10 ± 3 d). Sixty-seven percent of queens (4/6) treated with subcutaneous cat seminal plasma, and 17% of those treated with purified llama ß-NGF showed high serum progesterone concentrations along with prolonged interestrus. However, intramuscular administration of cat seminal plasma produced interestrus intervals similar to controls (15 ± 5 d) and basal serum progesterone concentration (<0.50 ng/mL). This study demonstrates that the subcutaneous administration of cat seminal plasma induced ovulation in queens. Therefore, molecules present in cat seminal plasma, contribute to the induction of ovulation in queens. Identifying those molecules will improve the knowledge of queen's reproductive physiology. Also, it could offer a physiologic alternative to induce ovulation in queens when reproductive biotechnologies are used.