Absorption of Escherichia coli endotoxin (lipopolysaccharide) from the uteri of postpartum dairy cows

An experiment was conducted to test the hypothesis that Escherichia coli (E. coli ) endotoxin is readily absorbed from uteri of early postpartum cows and that the absorbed endotoxin provokes systemic relcase of prostaglandins. Eleven postpartum Holstein dairy cows (aged 3 to 7 yr) with normal puerperium were selected and divided into a treatment group (n=7), which received intrauterine infusions of E. coli endotoxin, and a control group (n=4), which received intrauterine infusions of 10 ml of saline on Days 5 and 20 post partum. Blood samples were collected once every 30 min for 6 h starting from the time of infusion. Harvested sera samples were analyzed for concentrations of stable metabolites of prostacyclin (PCM), prostaglandin F(2alpha) (PGFM), and thromboxane A(2) (TXB(2)). Plasma samples were qualitatively tested for the presence of endotoxin. Endotoxin was detected in the plasma samples of cows that received endotoxin on Day 5 post partum 4 h after the infusion. Endotoxin was not detected in any of the samples from control cows on Days 5 and 20 post partum or from treatment group cows on Day 20 post partum. Cows treated on Day 5 post partum showed increases in serum PGFM concentrations from 710 +/-64pg/ml to peak concentrations of 1223 +/- 47 pg/ml within 2 h, followed by a decline to baseline concentrations within 4 h. The amount of PGFM released in treated cows on Day 5 post partum was higher (P < 0.05) than in control cows on Day 5 or in treated and control cows on Day 20 post partum. Serum PCM concentrations increased from 156+/-24 pg/ml to peak concentrations of 1348+/-127 pg/ml within 1 h. The amount of PCM released in treated cows on Day 5 postpartum was higher (P< 0.05) than in control cows on Day 5 or in treated and control cows on Day 20 post partum. The TXB(2) concentrations increased from 315+/-38 pg/ml to peak concentrations of 5043 +/- 242 pg/ml within 1 h and fell to baseline concentrations within 5 h. The amount of TXB(2) concentrations released in treated cows on Day 5 post partum was significant (P < 0.05) compared with those of cows in the other groups. The results support the hypothesis that uteri of early postpartum cows are capable of absorbing endotoxin, and the absorbed endotoxin provokes changes in the serum concentrations of prostanoids.     

Serum progesterone concentration in pyometritic and normal postpartum dairy cows

Two studies were conducted to evaluate the concentration of serum progesterone in pyometritic cows and relate it to palpation of ovarian structures per rectum . In Trial 1, serum samples from 34 pyometritic cows were assayed for progesterone. Mean serum progesterone concentrations were 6.8 +/- 0.7 ng/ml. In Trial 2, each of 54 pyometritic cows was paired with a control cow on the basis of days post partum (18-50 days). Mean concentration of progesterone was 9.7 +/- 1.0 ng/ml for the pyometritic cows and 5.7 +/- 0.8 ng/ml in control cows (P<0.005). Progesterone concentration was greater (P<0.005) in both groups of cows with palpable corpora lutea (CLs). Ninety-six percent of the pyometritic cows had palpable CLs compared to 57% of the control group. Comparing serum progesterone only in cows with a palpable CL, the mean concentration was still greater (P<0.005) in the pyometritic group (10.6 +/- 1.0 ng/ml) than the control group (6.6 +/- 1.0 ng/ml). Compatability of rectal palpation findings and concentrations of serum progesterone were 92.6% for the pyometritic group and 72.2% for the control group. Progesterone concentration increased (P<0.05) by increased days post partum in Trial 2 (n=54) but not in Trial 1 (n=23). In both Trials 1 and 2, uterine size due to pyometra increased (P<0.05) with increased days post partum. No other associations were found.     

Reproductive performance of dairy cows following treatment with fenprostalene, dinoprost, or cloprostenol between 24 and 31 Days post partum: a field trial

Three hundred and one Holstein cows (n=301), calving at a commercial free-stall dairy farm, were randomly assigned to 1 of 3 prostaglandin treatment groups or a placebo group. The placebos were packaged 3 ways to mimic the 3 commercial prostaglandin preparations. Group 1 received 1 mg fenprostalene and 1.6 mg oxytetracycline; Group 2 received the fenprostalene placebo (2 ml polyethylene glycol and 1.6 mg oxytetracycline); while Group 3 was given 25 mg dinoprost. Group 4, the dinoprost placebo received 5 ml saline; Group 5 received 500 ug cloprostenol; and Group 6 the cloprostenol placebo received 2 ml saline. The treatments were administered between Days 24 and 31 post partum. Double blind techniques were used in administering treatments and in assessing the response to treatment. There were no significant differences among treatment groups with respect to incidence of retained fetal membranes, endometritis, pyometra, anestrus, number of services per pregnancy, calving-to-first estrus interval, services per conception, number of prostaglandin treatments other than those administered between Days 24 and 31 post partum, the percentage culled for reproductive reasons and all factors combined. Cows receiving fenprostalene, dinoprost or cloprostenol had a decreased calving-to-conception interval compared with that of the controls (P = 0.05). It is concluded that, in the herd studied, treatment with any of the 3 commercially available prostaglandin products between Days 24 and 31 post partum was beneficial for reproductive performance.     

Use of plasma concentrations of 13,14-dihydro,15-keto-PGF2 alpha (PGFM) in the diagnosis of sub-clinical endometritis and its relationship to fertility in the postpartum dairy cow

The objective of this study was to determine the value of using plasma concentrations of PGFM to diagnose subclinical endometritis in the dairy cow, and its relationship to subsequent fertility. A total of 274 cows between 24 to 29 d post partum was divided into 4 groups on the basis of clinical features of the uterus and ovary. Cows in Group 1 (n = 74) had a normal, involuting uterus and a CL on the ovary; cows in Group 2 (n = 51) had a normal, involuting uterus but no CL on the ovary; cows in Group 3 (n = 83) did not have a normal, involuting uterus but had a CL on the ovary; and cows in Group 4 (n = 66) did not have a normal, involuting uterus or a CL on the ovary. A blood sample was obtained from each cow on the day they were placed on the study, and plasma concentrations of PGFM and P4 were determined using RIA. Cows were artificially inseminated (AI) at the first observed estrus after Day 60 post partum, and pregnancy was determined by palpation of the uterus per rectum between 45 and 50 d postAI. Reproductive responses evaluated were conception rate to first service, days open, and percentage of cows pregnant by 90, 120, 150 and 180 d post partum. Data were analyzed using GLM procedures of SAS and a 2 x 2 factorial with contrast procedures. Polynomial regression analysis was used to determine the shape of the PGFM, P4 and fertility curves. There was no difference among mean PGFM concentrations of cows in each group. The rate of decline of plasma PGFM concentrations was lower in cows with an abnormal uterus and a CL on the ovary compared with those without a CL. A lower percentage of cows with abnormal uteri was pregnant by 90 d post partum compared with cows with normal uteri. From the results of this study, it was concluded that plasma PGFM concentrations between Days 24 to 29 post partum were not effective in identifying cows with subclinical endometritis.     

Retained fetal membranes in cows: Manual removal versus nonremoval and its effect on reproductive performance

Sixteen primiparous Holstein cows with retained fetal membranes (RFM) were studied for postpartum prostaglandin release, uterine infection and resumption of estrous cyclicity after manual removal of RFM (eight cows) versus leaving the RFM untreated (eight cows). The RFM were results of induced parturition on Day 274 of gestation. Seventeen non-RFM primiparous cows were controls. The 15-keto-13, 14-dihydro-metabolite of prostaglandin F(2alpha) (PGFM) was measured in daily blood samples. Aerobic and anaerobic bacteria were cultured from weekly uterine swabs from Week 3 until results were negative. Resumption of estrous cyclicity was determined by milk progesterone three times weekly. Manual removal caused an immediate and large but short-lived increase in PGFM, probably due to the physical damage of uterine tissue. No sustained difference in postpartum PGFM release between cows with RFM manually removed and cows with RFM left untreated was detected. Non-RFM controls had lowest PGFM concentrations. Uterine infections were more frequent and more severe after manual removal of RFM. Untreated RFM-cows and controls were similarly affected. Most infections involved Actinomyces (formerly Corynebacterium ) pyogenes and/or Fusobacterium necrophorum . Actinomyces pyogenes was isolated in the third week postpartum in 5 8 cows with RFM manually removed versus 2 8 cows with RFM left intact and in 2 17 controls. Manual removal prolonged the interval from calving to first functional corpus luteum by 20 d. This study, using RFM resulting from induced parturition, shows that manual removal of RFM can delay the postpartum return to normal reproductive status without altering PGFM profiles.     

Circulating PgF2alpha and nutritional parameters at parturition in dairy cows with and without retained placenta: Relation to prepartum diet

Reproductive and biochemical parameters were studied at parturition in multiparous single-carrying Holstein cows. These were compared in animals with (n=14) and without (n=40) a retained placenta and then according to 2 prepartum diets (corn silage/concentrate, n=44; grass silage/concentrate, n=10) in cows with and without retained placentas. Cows with retained placentas had a 4-day shorter gestation period and gave birth to 5 kg-lighter calves than cows without retained placentas. Furthermore, their plasma PGFM -PgF2alpha main metabolite- (3325 vs 5675 pg/ml; P<0.01) and glucose (79.2 vs 95.2 mg/100ml; P<0.05) levels were lower and their protein concentration was higher (85.7 vs 76.5 g/l; P<0.05) than those of cows without retained placentas. Retained placenta incidence in cows fed grass-silage was higher than in cows fed corn-silage (60% vs 18.2%; P<0.05). Cows with retained placentas and fed corn silage had shorter gestation lengths, gave birth to lighter calves, and had less circulating glucose at calving (77.6 vs 96.5 mg/100ml; P<0.05) than cows without retained placentas and fed the same forage. Cows with retained placentas and fed grass silage had less PGFM (2172 vs 4530 pg/ml; P<0.05) than cows without retained placentas and fed the same forage. Calving number, sex ratio and preceeding milk yield were not different between the two groups of cows whatever their prepartum diet. In the dairy cow, retained placenta could be due to a PgF2alpha or an energy deficiency at calving. Roles of the dietary polyunsaturated fatty acids toward the Pg synthesis and of the energy supply before calving in relation to retained placenta are discussed here.     

The role of endogenous estrogens in the maturation process of the bovine placenta

The plasma estrogen and progesterone concentrations of 19 pregnant cows (average duration of pregnancy 266.0 +/- 2.3 d at the start of the study) were determined daily from Day 6 pre partum to Day 1 post partum. Parturition was induced in all cows by administration of 10 mg i.m. flumethasone. Values were centered around the delivery date (Day 0) following either induced normal calving (n = 3) or surgical delivery (n = 16). In animals showing spontaneous expulsion of the fetal membranes (Group 1, n = 6) the average total estrogen concentration increased significantly from Day 6 until Day 1 before parturition (1329.2 +/- 317.9 to 3719.8 +/- 951.2 pg/ml in total estrogens). A marked decrease was observed on Day 1 post partum (459.4 +/- 344.2 pg/ml). In comparison with Group 1, animals showing either a delayed or partial expulsion of the fetal membranes, or in which the placenta could be withdrawn 16 h after calving (Group 2, n = 5), had consistently lower total estrogen concentrations between Day 6 (595.4 +/- 174.8 pg/ml) and Day 1 (1884.3 +/- 565.1 pg/ml) before parturition. The estrogen values of the cows with retained placenta (Group 3, n = 8) from Days 6 to 0 pre partum were significantly lower than those of Group 2. Total estrogen concentrations of the three groups 1 d post partum did not differ significantly. It is generally recognized that estrogens play an important role in the maturation process of the placentomes. Our investigation demonstrates that not only is the magnitude of the prepartum rise in estrogens of great influence of the maturation process but the duration of this rise is likewise important. These two factors are vital for a normal expulsion of the fetal membranes.     

Spontaneous uterine infections are associated with elevated prostaglandin F(2)alpha metabolite concentrations in postpartum dairy cows

Postpartum Holstein (n=21) and Jersey (n=4) cows were used to determine if uterine infections are associated with elevated plasma concentrations of 13,14-dihydro-15-keto-prostaglandin F(2)alpha (PGFM). Based upon clinical examinations and bacterial content of intrauterine fluid samples, cows detected with uterine infections between 21 and 28 d post partum were used (infected; n=14). These cows were matched with herdmates that were free of infection (control; n=11). Beginning on the day the cows were assigned to the experiment (Day 1), blood samples were collected on alternate days for the next 14 to 15 d. Plasma samples were stored at -20 degrees C until assayed. From Day 1 until the end of the experiment, uterine fluid samples were collected transcervically twice weekly for aerobic bacterial culture. Endometrial biopsies were collected between Days 6 and 8 and Days 13 and 15. Control cows did not show signs of uterine infection throughout the trial, and bacterial cultures indicated that there were no significant bacterial populations in the uteri of the control cows. The uteri of infected cows harbored numerous microbes. Actinomyces pyogenes was most prominent. Various species of Streptococcus and Pasteurella were also prevalent in the infected cows. Escherichia coli was present in the uterus of both infected and control cows. Biopsies showed that infected cows had more (P<0.05) neutrophils, plasma cells and lymphocytes in the endometrium than did the control cows. As determined by plasma progesterone concentrations, 83% of the control and 50% of the infected cows had functional luteal tissue during the 2-wk sampling period. Plasma PGFM profiles were linear (P<0.03) and did not differ between treatment groups (P>0.01). However, average plasma PGFM concentrations were greater (P<0.0001) in infected than in control cows. These data indicate that plasma PGFM concentrations are greater in postpartum cows with spontaneous uterine infections then in herdmates free of infection.     

Effect of repeated administration of PGF2alpha in the early post partum period on the prevalence of clinical endometritis and probability of pregnancy at first insemination in lactating dairy cows

Two experiments were performed to determine the effects of repeated administration of PGF2alpha in the immediate post partum period on the prevalence of clinical endometritis at 22 and 58 days post partum, and the probability of pregnancy at first insemination, in post partum dairy cows. In Experiment 1, 228 cows on day 7 post partum were used. Cows in Group 1 (n = 114) were treated twice with PGF2alpha (25 mg, im) 8 h apart on days 7 and 14 post partum, and only once on days 22 and 35 post partum. Cows in Group 2 (n = 114) served as untreated controls. Vaginoscopy and transrectal palpation of the genital tract were done on days 22 and 58 post partum. Cows in both groups were inseminated at estrus after a voluntary waiting period of 100 days. Pregnancy was determined by transrectal palpation between 45 and 50 days after insemination. Repeated administration of PGF2alpha in the immediate post partum period did not reduce the prevalence of clinical endometritis on days 22 or 58 post partum (65 versus 62% on day 22 and 28.3 versus 35.2% on day 58 in Groups 1 and 2, respectively). There was no significant difference in the probability of pregnancy at first insemination between cows in both groups. In Experiment 2, 418 cows on day 7 post partum were used. Cows in Group 1 (n = 209) were treated twice with PGF2alpha (25 mg, im) 8h apart on days 7 and 14 post partum, and only once on days 22 and 35 post partum. Cows in Group 2 (n = 209) served as untreated controls. Cows in both groups were subjected to the Presynch and Ovsynch protocols on days 49 and 75 post partum, respectively. Pregnancy was determined by transrectal ultrasonography between days 29 and 32 after timed insemination. There was no significant difference in the probability of pregnancy at first insemination between cows in both groups. In conclusion, repeated administration of PGF2alpha to cows in this herd had no effect on the prevalence of clinical endometritis at 22 and 58 days post partum, and that there was no effect on the probability of pregnancy after insemination at estrus among cows with a voluntary waiting period of > 100 days, or at timed AI at 85 days in milk when Presynch was employed.     

Use of cow-side progesterone tests to improve reproductive performance of high-producing dairy cows

This study evaluated the effectiveness of the cow-side ELISA milk progesterone test in improving postpartum reproductive performance in the Dordt College dairy herd. Cows that produced more than 18,500 lb of milk per lactation were assigned to the high production group (40 cows), while cows that produced less than 18,500 lb of milk (42 cows) were assigned to the low production group. Twenty-one cows in the high production group and 19 cows in the low production group received no ELISA testing (untreated controls), while the remaining cows in each group were evaluated by ELISA test every 7 d beginning on Day 27 post partum (treated cows). A sequence of 2 high progesterone tests and 1 low test indicated the cows were cycling normally. Cows that had low milk progesterone levels (<5 ng/ml) for 3 consecutive tests were assumed to have follicular cysts and were treated with 2 ml GnRH (Cystorelin, 50 mug/ml). Cows that had 3 consecutive high tests (>5 ng/ml) were assumed to have persistent corpora lutea (CL) and were treated with 5 ml PGF(2)alpha (Lutalyse, 5 mg/ml). In both the high and low production groups, treated cows had higher (P < 0.08) pregnancy rates by Day 210 than the untreated controls (63.2 vs 38.1% and 56.5 vs 42.1%, respectively). The days open were reduced (P < 0.05) for the treated animals by 41.6 d compared with the controls. The treated cows produced a net savings of $70.42 (US) per cow assuming a $3.00 savings/day open.     

Relationship between endotoxin and prostaglandin (PGE2 and PGFM) concentrations and ovarian function in dairy cows with puerperal endometritis

Blood concentrations of progesterone, 13,14-dihydro-15-keto-prostaglandin F2alpha (PGFM) and endotoxin, and uterine fluid concentrations of prostaglandin E(2) (PGE(2)), PGFM and endotoxin were evaluated in 14 dairy cows with puerperal endometritis (mild (n=6) and heavy (n=8)). Endotoxin was measured using a quantitative kinetic assay. Cows with heavy endometritis had significantly higher concentrations of plasma PGFM (P<0.01) and uterine fluid PGE(2) and endotoxin (P<0.05) than cows with mild endometritis. Concentrations of PGFM in plasma and uterine fluid, of PGFM and PGE(2), and PGE(2) and endotoxin in uterine fluid were positively and significantly (P<0.05) correlated. The presence of endotoxin in plasma was detected in one out of six mild and in eight out of eight heavy endometritis cows. Peak plasma endotoxin concentrations (0.08-9.14 endotoxin units/ml (EU/ml) were observed between 1 and 12 days postpartum (pp) and thereafter amounts generally remained below 0.1 EU/ml (last day of detection: Day 27 pp). Abnormal ovarian function was observed in six cows (four with prolonged anoestrus and two with long luteal phase after the first postpartum ovulation). Plasma endotoxin concentrations were detected in the anoestric cows. The results suggest that: (i) concentrations of uterine fluid endotoxin and PGE(2) and of plasma PGFM are related to the degree of endometritis; (ii) absorption of endotoxin from the uterus to the bloodstream occurs, mainly in heavy endometritis cows; and (iii) there is a relationship between uterine infection, endotoxin production and resumption of pp ovarian activity.     

Postpartum adrenocortical function in dairy cows with dystocia submitted to cesarean section

The effects of the stress of dystocia on the adrenocortical function post partum in cows (n = 6) requiring a cesarean section were assessed by an adrenocorticotropic hormone (ACTH) stimulation test. Nine cows that calved normally were used as controls. The plasma glucocorticoid levels, before and 60 min after an intramuscular injection of 25 IU ACTH, were 4.4 +/- 0.5 (mean +/- SD) and 21.5 +/- 2.4 ng/ml 1 d post partum, 1.9 +/- 0.3 and 18.4 +/- 2.9 ng/ml 4 d post partum and 2.7 +/- 1.1 and 14.6 +/- 3.3 ng/ml 8 d post partum, respectively. Corresponding values of glucocorticoids in cows with normal calving were 4.5 +/- 3.6 and 18.1 +/- 5.2 ng/ml 1 d post partum, 1.7 +/- 1.3 and 13.2 +/- 5.5 ng/ml 4 d post partum and 1.9 +/- 1.7 and 14.6 +/- 3.3 ng/ml 8 d post partum. There were no statistically significant differences of the values between cows with dystocia requiring a cesarean section and cows with normal calving. The results indicate that dystocia requiring a cesarean section like normal calving does not lead to significant depression of the adrenocortical function post partum.     

Effects of calcium salts of fatty acids and calcium salt of methionine hydroxy analogue on plasma prostaglandin F2alpha metabolite and milk fatty acid profiles in late lactation Holstein-Friesian cows

Effects of a dietary lipid supplement containing calcium salts of fatty acids and methionine hydroxy analogue on plasma prostaglandin F2alpha (PGF2alpha) metabolite (PGFM) and milk fatty acid profiles were examined in 40 late lactation, nonpregnant, Holstein-Friesian cows for a period of 70 days. Effects on milk production, milk composition, and blood metabolites were also examined. Cows were paired on the basis of lactation number (first lactation, n = 8; second lactation, n = 32) and randomly assigned from within pairs to one of two dietary treatments: unsupplemented control (C) or 400 g per cow per day of the lipid supplement (S). Cows receiving the supplement had higher (P < 0.05) total milk production, total fat production (kg), and total lactose production (kg). Plasma cholesterol was significantly higher (P < 0.01) after 30 days of treatment in cows receiving the supplement. Cows receiving the supplement had lower (P < 0.01) concentrations of short chain milk fatty acids (C4:0 to C14:1) and higher concentrations of long chain fatty acids (C18:1 and C18:2; P < 0.01) than control animals. Oxytocin-induced prostaglandin release on Day 16 postovulation was increased (P < 0.01) in cows receiving the supplement. In conclusion, supplementation with calcium salts of fatty acids and methionine hydroxy analogue significantly increased milk yield and plasma PGFM.     

Serum cholesterol and triglycerides in postpartum beef cows and their relationship to the resumption of ovulation

The variations in lipid metabolism according to the physiological stage and their relationship to the resumption of postpartum ovarian cyclicity were assessed in Limousine beef cows fed a grass diet over 3 yr. Weekly blood samples were collected from 59 cows beginning 10 wk before to 20 wk after calving to evaluate serum cholesterol and triglyceride concentrations and electrophoretic lipoprotein fractions. After parturition, progesterone concentrations were also measured at weekly intervals to determine time of resumption of ovulation. Cows were categorized by resumption of postpartum ovarian cyclicity into 3 groups: early (4 to 6 wk post partum, n = 36); mid (7 to 10 wk post partum, n = 46) and late (after 11 wk post partum, n = 38). Higher serum triglyceride values (P<0.05) were observed during the last 10 wk of pregnancy (0.36+/-0.15 g/L) than during the first 20 wk of suckling (0.29+/-0.09 g/L). Cholesterol values decreased significantly (P<0.05) at the end of pregnancy, were minimal (1.01+/-0.03 g/L) at parturition, and increased again up to 9 wk post calving. Increased cholesterolemia and low serum triglyceride values after calving could be linked to the increased bovine alpha-lipoprotein fraction and decreased beta fraction. Serum triglyceride concentrations were not related to the resumption of postpartum ovarian cyclicity. Higher serum cholesterol values were observed from 2 wk before to 4 wk after calving in cows with early rather than mid and late resumption of ovarian cyclicity. Therefore, modifications in lipid metabolism during the puerperium seem to be related to resumption of cyclicity during the early postpartum period.     

Embryonic mortality and the uterine environment in first-service lactating dairy cows

Embryos were collected non-surgically from the tip of one uterine horn of 23 lactating dairy cows on Day 7 of pregnancy. Embryos were classified on the basis of morphological criteria as normal (n = 12) or abnormal (n = 13). Abnormal embryos were further classified as cleavage stage (n = 9) or morula/blastocyst (n = 4). Cows producing an abnormal embryo did not differ in days post partum at oestrus, age or parity from cows producing a normal embryo. Cows with an abnormal morula/blastocyst also did not differ with respect to days post partum at oestrus from cows with abnormal cleavage-stage embryos but cows with an abnormal morula/blastocyst were significantly older and of greater parity than cows with an abnormal cleavage-stage embryo. Hepes-saline-PVP solution (30 ml) was initially infused into the uterine tip, mixed and then withdrawn with a syringe. Analysis of this fluid revealed that the concentrations of glucose, total protein, calcium, magnesium and potassium were significantly higher in the flushings from the uterus of cows with abnormal embryos than from cows with normal embryos and zinc and phosphorus tended to be higher in the uterine flushings of cows with abnormal embryos. Phosphorus, total protein, calcium and magnesium tended to be higher in the flushings from cows with abnormal morulae/blastocysts than from cows with abnormal cleavage-stage embryos. Plasma progesterone did not differ between cows with normal or abnormal embryos or in cows with abnormal morulae/blastocysts or abnormal cleavage-stage embryos. Most embryonic mortality therefore occurred before Day 5 (during cleavage) in these cows.(ABSTRACT TRUNCATED AT 250 WORDS)     

Nutritional regulation of body condition score at the initiation of the transition period in primiparous and multiparous dairy cows under grazing conditions: milk production, resumption of post-partum ovarian cyclicity and metabolic parameters

The objective of this study was to investigate the effect of different body condition score (BCS) at 30 days before calving (-30 days) induced by a differential nutritional management from -100 days until -30 days on productive parameters, the interval to first ovulation and blood parameters in primiparous and multiparous Holstein cows under grazing conditions until 60 days post partum. The experimental arrangement was a randomized complete block design, where cows were blocked according to BW and expected calving date and then randomly assigned to different nutritional treatments from -100 to -30 days relative to calving to induce different BCS. As the assignment of cows to treatments was random, cows had to lose, maintain or gain BCS; thus, different planes of nutrition were offered with approximately 7, 14 or 20 kg dry matter per day. The BCS score was assessed every 15 days and animals were reassigned in order to achieve the desired BCS at -30 days. Only animals that responded to nutritional treatment were considered and this was defined as follows: primiparous and multiparous high cows (PH and MH) had to gain 0.5 points of BCS, primiparous low (PL) had to lose 0.5 points of BCS and multiparous low (ML) had to maintain BCS at least in two subsequent observations from -100 to -30 days. From -30 days to calving, primiparous and multiparous cows (P and M cows) were managed separately and cows were offered a diet once a day. From calving to 60 days post partum, cows of different groups grazed in separate plots a second year pasture. Cows were also supplemented individually with whole-plant maize silage and commercial concentrate. Cows had similar BCS at -100 days and differed after the nutritional treatment; however, all groups presented similar BCS at 21 days post partum. The daily milk production and milk yield at 60 days post partum was higher in M than P cows. The percentage of milk fat was higher in PH cows compared with PL cows. Concentrations of non-esterified fatty acids (NEFA) were affected by the BCS at -30 days within parity, and in PH cows the concentration of NEFA was higher than in PL cows. The concentrations of total protein were higher in M cows. A lower probability of cycling was found in PL than in PH cows (P < 0.05) and in ML than in MH cows (P < 0.05). Treatment affected various endocrine/metabolic profiles according to parity, suggesting that the metabolic reserves signal the productive/reproductive axis so as to induce a differential nutrient partitioning in adult v. first-calving cows.     

Effect of Actinomyces pyogenes and gram-negative anaerobic bacteria on the development of bovine pyometra

Fifteen lactating Holstein cows were used in a trial designed to evaluate the effectiveness of intrauterine inoculation (challenge) of Actinomyces pyogenes (A) alone or in combination with Fusobacterium necrophorum (F) and Bacteroides melaninogenicus (B) to induce pyometra. Cows were assigned to one of five groups: A (n = 3), AB (n = 3), AF (n = 3), ABF (n = 3) or C (control, broth medium alone; n = 3). All cows exhibited estrus 12 or 13 d prior to challenge (Day 0=first day of challenge). During the prechallenge period, the reproductive tract of each cow was palpated per rectum and uterine fluid aspirates for culture and uterine biopsies were also obtained. All cows received an intravenous injection of 5,000 IU of human chorionic gonadotropin (hCG; Day 5) and an intrauterine infusion of 40 ml of 0.7% iodine solution (Day 1). Cows were then inoculated on Days 0, 1 and 2 of the experiment. Sequential palpations of the reproductive tracts, samples of uterine fluid for culture and uterine biopsies were performed for a total of 30 d after the first inoculation. A cow was diagnosed as having pyometra when purulent uterine fluid and a corpus luteum were detected by palpation per rectum. The number of cows that developed pyometra in Group A was 2 of 3, in Group AB 3 of 3, in Group AF 3 of 3, in Group ABF 3 of 3 and in Group C 0 of 3. Cows with pyometra did not exhibit estrus. In 7 of 11 cows, pyometra persisted for more than 21 d. In cows that developed pyometra, the same species of bacteria infused into the uterus were usually recovered one or more times during the postchallenge period. When clinical pyometra was diagnosed, histologic endometritis was invariably present. Histologic endometritis and concurrent isolation of A . pyogenes alone or A . pyogenes with gram-negative anaerobic bacteria occurred in 91.7% of samples during the postchallenge period. Regardless of bacterial treatment, gram-negative anaerobic bacteria were frequently isolated with A . pyogenes during this period.     

Effect of genetic merit, milk yield, body condition and lactation number on in vitro oocyte development in dairy cows

The effects of milk yield, body condition score (BCS) and lactation number on the number of oocytes recovered and blastocysts formed were studied following in vitro maturation, fertilization and culture of bovine oocytes collected from 48 high and 46 medium genetic merit dairy cows in their first and third lactation. The cows were slaughtered between 125 and 229 d post partum. Ovaries were recovered, and 2- to 10-mm follicles were aspirated. Cleavage rate and number of blastocysts were determined at 44 h and 7 d after insemination, respectively. Oocytes from high genetic merit cows formed fewer blastocysts and had lower cleavage and blastocyst formation rates than those from medium genetic merit cows (0.36 +/- 0.19, 70.4 and 6.8% vs 0.85 +/- 0.22, 77.4 and 11.4%, respectively). The effect of milk production was tested by grouping cows in their third lactation into high and low groups. There was no difference in number of oocytes recovered and subsequent development into blastocysts between the cows in the high milk production group (4559 to 5114 kg, n = 20) and cows in the low yield (3162 to 3972 kg, n = 20) group (6.9 +/- 1.34 vs 8.9 +/- 1.32, respectively). The effect of BCS was tested by grouping cows in their first or third lactation into high and low groups. Cleavage and blastocyst formation rates were greater for oocytes from cows with a high BCS (3.3 to 4.0, n = 20) than a low BCS (1.5 to 2.5, n = 20) (75.7 vs 61.9% and 9.9 vs 3.0%, respectively). Cows in the first lactation yielded fewer oocytes (5.7 +/- 1.24) than cows in the third lactation (7.8 +/- 0.79). Thus, the quality of oocytes probably contributes to reduced fertility, often evident in high genetic merit dairy cows.     

Postpartum uterine flora following normal and abnormal puerperium in cows

Uterine swabs were taken from the uteri of three groups of cows (n = 5 each) on Days 1 and 2 and then at 3-d intervals up to 32 d post partum. Group I cows had a normal delivery, Group II cows had dexamethasone-induced parturition, and Group III cows were subjected to a Caesarian section. All cows in Group III and two cows in Group II retained their fetal membranes. A total of 230 bacterial isolates were made, and the most frequently isolated bacteria were Escherichia coli , streptococci, Proteus spp. , and clostridia. The highest number of bacterial isolates and the longest mean time to complete uterine involution were in the Group III cows.     

Progesterone profiles in postpartum Holstein dairy cows as an aid in the study of retained fetal membranes, pyometra and anestrus

This study was carried out to investigate the utility of enzymeimmunoassay (EIA) - derived progesterone profiles in the investigation of postpartum reproductive abnormalities and the effect of their use on reproductive performance in Holstein cows. Whole milk samples, collected twice weekly from parturition until confirmation of pregnancy or removal from the herd, were assayed for progesterone (P4) concentration using a commercially available microtitre plate EIA. The sensitivity, specificity, precision and accuracy were satisfactory to distinguish cyclic changes of P4 reflecting ovarian activity. The P4 profiles indicated that retained fetal membranes and anestrus were associated with increased mean intervals to first ovulation and first estrus (P < 0.05). The first luteal phase of cows with pyometra was prolonged compared with that of normal herdmates (P < 0.05). Anestrus cows had an increased number of ovulations before first service and before pregnancy (3.9 and 5.9) in comparison with normal herdmates (2.1 and 3.5; P < 0.05). Calving to pregnancy interval was increased above normal (74.8) for pyometra (125.0) and anestrus (152.7) (P < 0.05). Pregnancy rate for anestrus cows (82%) was lower than for normal cows (100%) and more anestrous cows were culled (27%) than normal cows (5%) (P < 0.5). The P4 profiles indicated that the major problem in the herd studied, anestrus (32% incidence rate), was most likely due to the failure to observe estrus rather than acyclicity.