The use of dimenhydrinate in conjunction with dexamethasone for induction of parturition in beef cattle

Forty-eight crossbred Chianina cows (3 to 5 years of age), with an expected gestation length of 288 days, were randomly divided into four treatment groups to evaluate the use of dimenhydrinate (an antihistamine agent) in conjunction with dexamethasone (DEX) for inducing parturition in beef cattle. Group (A) received a 20 mg dose of DEX (im) on day 282 of gestation and a carrier vehicle (iv) 24 hours later (day 283); Group (B) was given a carrier vehicle (im) on day 282 and 500 mg of dimenhy-drinate (DMH) diluted in 200 ml of 2.5% dextrose-0.9% saline solution given (iv) on day 283 and Group (C) received 20 mg of DEX (im) on day 282 and 500 mg of DMH in solution (iv) on day 283 of gestation. The remaining 12 cows assigned to Group (D) were not handled and were allowed to calve under natural conditions. The number of cows calving and percent calving within 60 hours after the first injection were: 10(91%), none(0%) and 12(100%) for the DEX, DMH and DEX plus DMH groups, respectively. The mean gestation length of the control cows in Group (D) was 288.6 days. Frequency of dystocia was: 18.2, 8.3, 0 and 0% and retained placentae (>/=24 hours) was: 72.8, 16.6, 33.3 and 0% for DEX, DMH, DEX plus DMH and control groups, respectively. In this study, a 20 mg dose of DEX (im) followed 24 hours later with 500 mg of DMH (iv) was more successful for calving induction than when DEX or DMH was used alone. The combination DEX and DMH treatment induced calving in a shorter interval from treatment (P<.05) and decreased the incidence of retained placentae (P<.01) when compared with those induced following DEX treatment.     

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.     

Effect of corticoid induced parturition on lactation and on prepartum profiles of serum progesterone and the estrogens among cows retaining and not retaining fetal membranes

Twenty-one mature F1 Brahman-Hereford cows were treated with 25 mg of dexamethasone (DEX) on day 279 or 280 of gestation to induce birth prematurely. Eigth cows were untreated (UT). Blood was sampled on day 279 or 280 of gestation just prior to treatment of cows with DEX (0 hr), at least daily thereafter to calving and within 1 hr postpartum. Concentrations of progesterone (P₄), estrone (E₁) and estradiol-17β (Eβ) and -17α (Eα) in blood serum were measured by radioimmunoassay. Among 21 cows treated with DEX, 16 (76%) calved within 78 hr (52±3 hr). Eleven of the 16 cows retained fetal membranes more than 12 hr (RFM) and five cows did not retain fetal membranes (NRFM). Five cows (24%) treated with DEX calved 266±46 hr later (NOR) on day 290±1 of gestation compared to day 286±2 for cows in group UT. No cow in groups NOR or UT had RFM. Failure of group NOR to calve prematurely appeared due to elevated serum P₄ (P<.05), low serum Eβ (P<.10) and other estrogens (P>.10) pretreatment, and to only a 32% decrease in serum P₄ within 72 hr after treatment. Serum estrogens, especially Eβ, were next lowest pretreatment in group RFM. However, in group RFM, all serum estrogens increased (P<.10 to P<.01) within 48 hr after treatment, reached higher concentrations and peaked later in relation to calving than in other groups (NRFM, NOR and UT). Synchronization of placental maturation and parturition may require a longer period of elevated serum estrogens prior to calving than was observed in group RFM. Treatment of cows prepartum with DEX had no effect on gain of calves, milk yield or yields of fat, total protein and total solids in milk during the first 12 weeks of lactation.     

Induction of parturition in Zebu-cross recipients carrying in vitro-produced Bos indicus embryos

Induction of parturition has been used as a management tool in cattle in several countries, but not commonly in Zebu breeds in tropical production systems. When timed according to the stage of gestation, most induction protocols employing a combination of PGF2alpha and a potent, short-acting corticosteroid, resulted in a predictable interval from induction to calving, with no detrimental effects on calf viability; however, the incidence of placental retention was usually elevated. Pretreatment with a long-acting corticosteroid induced placental maturation and greatly reduced the incidence of placental retention following induction with PGF2alpha and a short-acting corticosteroid. Recently, Brazilian cattle breeders have faced a new challenge with a large number of in vitro-produced embryos. Without a reliable method of cryopreservation, large numbers of embryos have been transferred fresh, creating a new demand for protocols for synchronizing recipients and managing their calving. A parturition-induction protocol, efficacious in Bos taurus cattle, was modified for use in Bos indicus cattle (which generally have a longer gestation than B. taurus cattle). Zebu-cross recipients carrying Nelore in vitro-produced embryos were pretreated with 1 mg/60 kg triamcinolone acetonide on Day 280 of gestation, followed by treatment with 500 microg of cloprostenol and 25 mg of dexamethasone on Day 287. The interval from treatment to calving was predictable and the incidence of retained placenta was low, similar to that described previously for B. taurus cattle, demonstrating that this treatment protocol could be used for induction of parturition in Zebu cattle in Brazil.     

Selective induction of parturition in cattle

Sixty pregnant beef cows 2 to 10 yrs of age were assigned to a control or treated group. Treated cows received 3.5 mg of flumethasone at 1600 hrs on each consecutive Monday, beginning 20 to 2 days prior to expected term and continuing until parturition occurred. Cows were successfully induced with 1, 2 or 3 treatments of flumethasone. Cows requiring 2 or more treatments (7 days apart) to induce parturition had parturition limited to only 2 days a week. Induction treatments resulted in: shorter gestations (P=.001); no reduction in birth weights; no increase in calving difficulty; improved calf vigor (P=.058) and increased incidence of retained placenta (P=.024).     

Prevention of the retained fetal membrane syndrome (retained placenta) during induced calving in dairy cattle

Sixty-six dairy cattle were induced to calve with dexamethasone treatment at 5 d prior to expected time of calving. Each animal was assigned randomly to one of two treatments, saline (2 ml) or PGF(2)alpha (10 mg), which were administered within 1 h postpartum. With the saline treatment, 90.5 % of the animals had placental retention, whereas only 8.8 % of the PGF(2)alpha-treated animals had placental retention. The PGF(2)alpha-treated cows released the fetal membranes in 7.4 +/- 1.35 h postpartum, whereas the saline-treated cows released the membranes in 98.3 +/- 10.93 h postpartum. These data demonstrate that treatment with PGF(2)alpha within the immediate postpartum period is effective (P < 0.001) in the prevention of placental retention in the dairy cow induced to calve with dexamethasone.     

Synchronization of parturition in beef cattle with prostaglandin and dexamethasone

The effectiveness of dexamethasone and prostaglandin in combination for induction and synchronization of parturition in cattle was evaluated in 100 pregnant Angus, Hereford, Charolais and Simmental cows. Cows were distributed equally by breed, day of gestation and cow age to one of three treatments: 1) Control, 2) Dexamethasone (25 mg) plus prostaglandin F(2alpha) (25 mg) or 3) Dexamethasone (25 mg) plus fenprostalene (1 mg). Hormones were administered simultaneously from 275 to 283 d of gestation. Gestation length at calving for control cows differed significantly (P < 0.01) among breeds: Angus, 278.5 +/- 0.9; Hereford, 283.1 +/- 1.1; Charolais, 283.2 +/- 1.5; and Simmental, 285.4 +/- 1.2 d. For hormone-treated cows, 80% of the calves were born between 30 and 46 h after the hormone injections; overall mean was 37.6 +/- 1.1 h. Calving response did not differ (P >0.1) between cows treated with prostaglandin F(2alpha) versus fenprostalene (36.5 +/- 1.6 vs 38.6 +/- 1.6 h) or among cow age, day of gestation, or breed. Also, duration of labor, calving difficulty and calf viability did not differ between calves born at an induced or spontaneous parturition. The incidence of placenta retained for >24 h was higher for induced than spontaneous parturition (21.0 vs 0.0%), but it did not differ (P >0.1) between cows treated with prostaglandin F(2alpha) or fenprostalene (19.2 vs 22.6%). An acceptable degree of synchrony of parturition was attained by the administration of prostaglandin F(2alpha) or fenprostalene in combination with dexamethasone. The higher incidence of retained placenta in treated than control cows did not affect subsequent fertility. The longer biological half-life for fenprostalene than for prostaglandin F(2alpha) provided no improvement in increasing synchrony of parturition or decreasing frequency of retained placenta.     

Induction of parturition in conjunction with antibiotic treatments

Parturicion was induced in pregnant beef cows and heifers with 15 mg of flumethasone to test: 1) the effects of an orally active antibiotic on flumethasone induction of parturition success rate and incidence of retained placenta and 2) the effects of injectable long acting and orally active antibiotics on subsequent fertility and offspring performance. Gestation length and birth weight were not significantly changed. There were no significant differences among calving ease scores even though induction significantly improved vigor. Induction caused a significant increase in the incidence of retained placental membranes. Pregnancy rate (P<.01) and conceptions per service (P<.05) were lower for those animals affected with retained placentas. There were no significant differences among actual weaning weights for the three treatment groups or between adjusted weaning weights for the control and the orally active antibiotic groups, however, the adjusted weaning weights of calves from cows receiving an orally active antibiotic were significantly greater than those receiving an injectable long acting antibiotic (P<.10).     

Synchronization of parturition in beef cattle using delay as well as induction

Two methods for synchronization of parturition in beef cattle were examined. In the first experiment, four groups of cows and heifers were used: untreated (C, n=9), 10 mg flumethasone on day 281 of gestation (F, n=9), 100 mg progesterone daily from days 276 through 283 and 50 mg progesterone on day 284 (P, n=6), and (P + F on day 284, n=7). Variances in gestation lengths (C, 26.01; F, 0.77; P, 11.97; P + F, 1.93) and proportions of cows and heifers with retained placentas (C, 0 9 ; F, 4 9 ; P, 1 6 ; P + E, 0 7 ) differed significantly among groups. Differences among groups in calving difficulty scores and proportions of dead calves were not significant. Four of the thirteen cows and heifers treated with progesterone required assistance in calving and all four delivered dead calves. Pulling of these calves was not accompanied by uterine contractions. Conversely, the difficult calvings in the control- and flumetha-sone-treated cows and heifers were accompanied by uterine contractions. In the second experiment, two groups of cows were used: 1) a single injection of 20 mg dexamethasone on either day 276, 277 or 278 followed by injections of saline every 12 h for 2.5 additional days (n=6), and 2) repeated injections of 20 mg dexamethasone every 12 h for 3 days beginning on day 276, 277 or 278 (n=8). The interval from time of first treatment to calving was not different between groups (43.6 and 43.0 h, respectively). Differences between calving difficulty scores, proportions of dead calves and incidence of retained placentas were not significant. Induction very close to the expected calving date could reduce the problems of retained placenta; however, methods must be identified to safely delay parturition.     

Incidence of retained placenta following induction of parturition with corticoids or prostaglandins

Three trials involving 214 cows were conducted to 1) compare the timing of events during normal parturition with parturition induced with a corticoid or a prostaglandin; 2) determine if synchrony could be improved by injection of steroids either concurrently or after injection of a corticoid or a prostaglandin; 3) determine if the incidence of retained placenta could be reduced; and 4) explore methods of treating retained placenta. The timing of events following induction of parturition was compared with that following a normal parturition in 76 heifers. The time from onset of labor to appearance of the placenta, abdominal press, appearance of feet and expulsion of the fetus did not differ between normal and induced parturition. The time from onset of labor to calf standing was increased from 2.3 +/- 2.0 hours in normal parturition to 5.8 +/- 5.5 hours in cows receiving 10 mg of flumethazone (P<0.05). The interval from onset of labor to calf nursing also tended to be longer (P>0.05<0.01). All control cows expelled fetal membranes by 48 hours after onset of labor, but the proportion expelled by the treatment groups varied from 24 to 76%. None of the treatments used in this study significantly increased placental expulsion over that noted when flumethazone or prostaglandins were used alone. No difference in placental expulsion time was noted in cows douched with nolvasan or injected with 30 cc oxytetracycline. None of the treatments used in the three trials reported in this study improved synchrony of parturition over that noted in the cows receiving only an injection of flumethazone or prostaglandins.     

Effect of induction of parturition on immunoglobulin content of colostrum and calf serum

Thirty-four pregnant crossbred beef cows were injected with prostaglandin F(2) alpha (PGF group, n = 11), dexamethasone (DEX group, n = 11), or saline (control group, n = 12) on Day 270 of gestation. Immediately after calving, all colostrum was milked from each cow. A sample was taken, and the remainder was fed to that cow's calf within one hour of birth. Serum was collected from each calf at 0 and 24 h of age. Immunoglobulin G (IgG) content of colostrum and serum was determined with commercial radial immunodiffusion plates. The data from four PGF cows that did not calve until after 140 h post injection were excluded from the results. Mean (+/- SD) volumes (ml) of colostrum were 2086 (+/-1148.4) for the PGF group, 1336 (+/-583.7) for the DEX group, and 2404 (+/-1140.7) for the control group. Mean (+/- SD) concentrations (mg/dl) of IgG in colostrum were 6017 (+/-3351.2) for PGF, 10285 (+/-5370.7) for DEX and 10766 (+/-5098.3) for the control group. Mean (+/- SD) total quantities of IgG (g) in colostrum were 133.9 (+/-120.03) for PGF, 134.1 (+/-96.67) for DEX and 235.6 (+/-147.22) for the control. IgG concentrations were very low or were not detectable in serum of all calves prior to administration of colostrum. Mean (+/- SD) concentrations (mg/dl) of IgG in serum of calves at 24 h of age were 1469 (+/-905.8) for calves from PGF cows, 1819 (+/-1289.8) for calves from DEX cows, and 3317 (+/-1888.2) for calves from control cows. Calves from control cows had significantly more IgG at 24 h than calves from PGF cows or DEX cows (p<0.05). Calves born to cows induced to calve early may be at an increased risk of failure of passive transfer and so should be monitored for IgG concentrations.     

Effects of cloprostenol sodium and clenbuterol HCl on reproductive performance in postpartum anestrous cows

Two experiments were conducted to study effects of cloprostenol sodium (cloprostenol) and clenbuterol HCl (clenbuterol) during postpartum anestrus on subsequent reproductive performance in cows. In Experiment I, 96 cows received either 0.5 mg cloprostenol (PGF, n = 25), 364 mg clenbuterol (CLEN, n = 24), 0.5 mg cloprostenol and 364 mg clenbuterol (CLEN+PGF, n = 21) or no treatment (Control, n = 26) on Day 20 post partum. Treatments failed to influence postpartum interval, pregnancy rate or the incidence of short estrous cycles preceding the first normal estrous cycle. In Experiment II, anestrous cows were administered cloprostenol (0.5 mg) on either Day 20 (PGF20, n = 27) or Day 35 post partum (PGF35, n = 25), or served as untreated controls (Control, n = 26). Neither postpartum interval nor pregnancy rate were affected by cloprostenol treatment. In conclusion, treatment of postpartum cows with PGF did not alter the resumption of normal estrous cycles following parturition.     

Postpartum oxytocin treatment for prevention of retained placentas

Some dairymen are attempting to reduce the incidence of retained placentas in their herds by routinely injecting oxytocin following parturition. Since there was little or no experimental evidence to support such a practice, a study was designed to test the influence of early postpartum oxytocin injection on the incidence of retained placentas. The study was designed so that every other cow in the University of Illinois dairy herd would receive an intramuscular injection of 100 IU oxytocin within three to six hours following calving. If the animal expelled the membranes before three hours she was placed in the control group. Two hundred cows calved during the one year study. In the 100 cow control group, twelve cows retained their fetal membranes whereas in the 100 cow treated group eight retained the placenta.     

Reproductive performance of lactating dairy cows treated with gonadotrophin-releasing hormone (GnRH) and/or prostaglandin F2a (PGF2a) for synchronization of estrus and ovulation

The objective of this study was to determine the reproductive performance of lactating dairy cows treated with GnRH and/or PGF2a for synchronization of estrus and ovulation. Between Days 43 and 57 post partum, a total of 374 dairy cows was divided into 4 groups. Cows in Group 1 (n = 62) were treated with 25 mg, i.m. PGF2a on Days 43 and 57; cows in Group 2 (n = 65) were not treated at this time; cows in Group 3 (n = 118) were treated with 100 ug, i.m. GnRH on Day 50, 25 mg, i.m. PGF2a on Day 57, 100 ug, i.m. GnRH on Day 59, and time-inseminated 16 h later; cows in Group 4 (n = 129) were treated with 25 mg, i.m. PGF2a once on Day 57. Cows in Groups 1 and 4 were inseminated at an induced estrus within 7 d after the last PGF2a treatment, and cows in Group 2 were inseminated at a noninduced estrus within a corresponding period of time. Conception rate, estrus detection rate and pregnancy rate were analyzed using logistic regression, and controlled for lactation number, body condition score and time of year. Days from calving to conception were analyzed using the GLM procedures of SAS, and the model included group, body condition score, lactation number, time of year, and their interactions. Cows in Group 3 had a significantly higher pregnancy rate than cows in Groups 1, 2 and 4. Orthogonal contrasts of mean days from calving to conception showed that cows in Group 3 had significantly (P < 0.01) less days from calving to conception than cows in Group 1 and Group 4. There was a significant effect of time of year on pregnancy rate and days from calving to conception, but there was no interaction between time of year and these reproductive characteristics. There was no effect of body condition score and lactation number on the reproductive characteristics evaluated. From the results of this study, it was concluded that better reproductive performance was observed in cows inseminated at a synchronized ovulation than in those inseminated at a synchronized estrous period.     

Increased incidence of retained placenta associated with heat stress in dairy cows

A dairy herd experienced an increased incidence of retained placenta and postpartum metritis during late spring and summer of 1977 and 1978. The incidence of retained placenta and postpartum metritis was 24.05% during the period of May through September compared to 12.24% the rest of the year. The gestation period of cows having retained placenta and postpartum metritis was an average of 5.25 days shorter than that of cows not exhibiting these symptoms. The gestation period of cows calving during the warm season was an average of 2.82 days shorter than that of the cows calving during the cool season. Heat stress resulting in early parturition was the probable cause of this increased incidence of retained placenta and postpartum metritis. The number of days open was influenced both by abnormal postpartum period and season of calving. Cows having retained placenta and metritis were open an average of 31.69 days longer than cows with normal postpartum periods. Cows that calved during the warm season were open an average of 24.42 days longer than those calving during the cool season.     

Dexamethasone and estradiol benzoate induced parturition in dairy cattle

Fifteen 2-year-old Holstein cows and 21 mature Holstein cows were assigned to one of three groups. Cows in Group I calved spontaneously. Cows in Groups II and III received single intramuscular injections of 20 mg dexamethasone and 25 mg estradiol benzoate to induce parturition prematurely. In addition, cows in Group III received a single intramuscular injection of 12.5 mg estradiol benzoate 48 hr prior to dexamethasone and estradiol benzoate. The objective of the experiment was to determine the effectiveness of estradiol benzoate in combination with dexamethasone on traits at parturition and on productive and reproductive characteristics following parturition. Induction of parturition shortened gestation length and increased the incidence of retained placentas (both P < .01). All induced cows calved between 21 and 59 hr postinjection with less (P < .05) udder edema when compared to control cows. Mean plasma estrogen concentrations, using an assay system which does not measure estradiol benzoate, were not different among groups following injections of estradiol benzoate. Mean estradiol-17β concentrations in induced cows, however, using an assay system which does recognize estradiol benzoate (70.8% crossreactivity), were higher (P < .01) following estradiol benzoate injection, tended to be higher through parturition, and remained elevated (P < .01) at 12 and 24 hr following parturition when compared to cows calving spontaneously. Mean monthly milk production and the 2x, 305-ME records for milk, fat and FCM were not different among groups.     

Postpartum subestrus in dairy cows: comparison of treatment with prostaglandin F2 alpha or GnRH + prostaglandin F2 alpha + GnRH

Two experiments (Experiment 1, 185 cows in 1996/97; Experiment 2, 168 cows in 1997/98) were conducted with Prim Holstein dairy cattle in the Mayenne region of France to investigate subestrus. Cows which had not been observed in estrus since calving were allocated alternately to treatment groups between 60 and 90 d post partum as follows: Experiment 1-Group 1: GnRH (Day 0, 100 micrograms i.m.), PGF2 alpha (Day 7, 25 mg i.m.), GnRH (Day 9, 100 micrograms i.m.) and AI (Day 10); Group 2: PGF2 alpha (Day 0, 25 mg i.m.), AI at estrus, or, if estrus was not observed, a second PGF2 alpha injection on Day 13, and AI on Day 16 and Day 17. Treatments in Experiment 2 were as follows: Group 1: as Experiment 1-Group 1 but AI at the observed estrus after Day 0, or at Day 10 if estrus was not observed; Group 2: as Experiment 1--Group 2, however, if a second PGF2 alpha injection was given on Day 13, AI at the observed estrus. Progesterone was measured in serum at Day 0 and in milk at AI. Pregnancy diagnosis was performed by measuring bovine pregnancy-specific protein B (bPSPB; Day 50 +/- 3) and confirmed by ultrasonography when the result was doubtful. In Experiment 1, farmers observed 47/101 (46.9%) Group 1 cows in estrus, 33/91 cows on Day 10 and 10 cows before Day 10. The progesterone concentrations were compatible with estrus in 69/86 (80%) cows on Day 10. In Group 2, 36/83 (43.4%) cows were inseminated after the first PGF2 alpha injection. After the second PGF2 alpha injection, only 29/43 (67%) cows had a low progesterone concentration at AI. Pregnancy rates were 36.1 and 32.5% for Groups 1 and 2, respectively. In Experiment 2, estrus was observed in 31/93 (33.7%) Group 1 cows. In Group 2, 51/75 (66%) cows were inseminated after the first injection of PGF2 alpha, 13/75 (17.3%) cows after the second injection, while 11/75 (14.7%) were not observed in estrus. Pregnancy rates were 53.7 and 53.3% in Groups 1 and 2, respectively. In conclusion, it is recommended that subestrus be treated with PGF2 alpha followed by AI at the observed estrus when estrus detection is good, while the use of GnRH + PGF2 alpha + GnRH is recommended when estrus detection is poor.     

The impact of uterine infection on a dairy cow's performance

The aim of this study was to assess the predisposing factors leading to uterine infection in dairy cows and evaluate its impact on the cow's performance. Performance indicators included feed intake, milk fat and protein composition, milk yield, fertility and culling. Data were studied from 2914 completed lactations from the Holstein Friesian Langhill Dairy herd between January 1990 and August 2005. There were 402 cases of uterine infection (from 321 cows) in the Langhill herd, a level of 13.8% during the study period. Calving assistance was highly associated with the incidence of uterine infection (chi(2)=106.63, P<0.001). Failure to conceive (chi(2)=3.89, P<0.05; chi(2)=11.20, P<0.001) and culling (chi(2)=13.66, P<0.001, chi(2)=8.55, P<0.01) were also implicated with calving assistance and uterine infection, respectively. The main predisposing factors related to an incidence of uterine infection were calving assistance, twin births, malpresented calves, and retained placenta. First-time calvers and cows with a shorter gestation length were associated with more cases of uterine infections. Additionally, lower daily dry matter intakes and milk yields during the first 100 days in milk (DIM) were associated with higher incidence levels of uterine infection. Also, a higher incidence level of uterine infection was related to lower milk protein composition from 1 to 21 DIM and a poorer body condition from 101 to 300 DIM. Cows with poorer drying off body condition scores and longer lactation lengths were associated with a higher incidence level of uterine infection. Calving assistance was associated with male and twin births, first-time calvers and cows with oversized calves. Cows with an assisted calving were also associated with an increased number of days from calving to first service. The predisposing factors influencing the occurrence of calving assistance can be influenced by suitable management to reduce the chances of oversized calves, the detrimental effects of twin births (such as calving assistance and retained placentas) and prenatal knowledge of the calf's sex. The occurrence of uterine infection can be reduced by minimising the need for assistance at calving. Assistance should only be carried out when necessary and appropriate hygiene should be used to decrease the incidence of uterine infections from intervention and involuntary culling due to cows failing to conceive.     

Factors related to the etiology of retained placenta in dairy cattle

Birth records of 369 288 calvings of 160 188 Meuse-Rhine-Yssel cows were analysed to assess the influence of factors associated with retained placenta. Special emphasis was placed on the analysis of a subset containing data on births involving a single live calf and an easy or normal calving process. The overall rate of incidence of retained placenta was 6.6%. The rate increased during the years studied. Abortion, stillbirth and multiple birth caused a marked increase in rate, as did difficult calving, caesarean section and fetotomy. After adjusting for these factors, analysis of the corrected subset showed that the rate of incidence increased with age of the dam. Gestation length prior to retention and birth weight were also associated with higher rates. The combination of short gestation length (<270 days) and low birth weight (⩽37 kg) was associated with the highest risk of retained placenta. High birth weights mainly caused higher rates when related to dystocia. The incidence rate in cows delivering a male calf was only slightly higher than in cows delivering a female calf. Cows having retained placenta for a first or second time were three and six times, respectively, as likely to do so again at a subsequent parturition when compared with cows which had not had retained placenta previously.     

Postpartum uterine motility measurements in dairy cows retaining their fetal membranes

Postpartum uterine contraction variables were measured in 15 parturient Holstein dairy cows and heifers: 8 assigned to dexamethasone (DEX) treatment and 7 to control (CON) treatment. The DEX animals were induced to calve early with an injection of dexamethasone and estradiol benzoate, administered on days 270 to 274 of gestation. At this time, the CON animals were injected with sterile saline and allowed to calve at term. Six of the eight DEX animals and one of the seven CON animals retained their fetal membranes longer than 12 hours postpartum. The uterine contraction variables determined were: the number of contractions over a 10 minute period (C 10 ), the average amplitude of contractions (AMP), the average duration of contractions (DUR), Montevideo units (MONT) and Alexandria units (ALEX). Recordings were taken at 1 hour, 6 hours and 48 hours postpartum, for a period of 20 minutes each. The contraction variables were measured using a catheter which was fluid-filled and inserted into the pregnant horn and connected to a pressure transducer, amplifier and recorder. The data were analyzed in terms of DEX vs. CON animals and animals with retained fetal membranes (RET) vs. animals with a normal release (NRET). Treatment with dexamethasone and estradiol benzoate resulted in an increase in C 10 at 48 hours (P < .05). The AMP, MONT and ALEX variables were also higher in the DEX animals, as compared to controls at that time. Significant differences (P < .01) were observed at 48 hours postpartum between the RET and NRET animals in terms of AMP, MONT and ALEX variables, and at that time the RET animals had a higher rate of uterine contractility than the NRET animals. No significant differences in the amount of uterine work between either the DEX and CON animals or the RET and NRET animals were observed, at 1 and 6 hours postpartum. The treatment with dexamethasone and estradiol benzoate prolonged uterine motility up to 48 hours postpartum, and the retention of the fetal membranes was not a result of the lack of uterine contractility during the early stages postpartum.