Detection of estrus in cattle housed in stanchions by constant human observation of behavioral traits.

Five heifers and five lactating dairy cows were locked in adjacent stanchions and monitored continuously by human observation for 18 consecutive nights from 7:00 p.m. to 4:00 a.m. Total standing and lying time, number of position changes, and prevalence of bellowing was recorded. The animals were housed in stanchions for 20 hours each day and in outside lots for four hours each day. Estrus was synchronized by giving prostaglandins on Days 1 and 11. There were 16 documented estrous periods, and an increase (P < 0.05) in standing time occurred in two of 16. Similarly, an increase (P < 0.05) in number of position changes occurred in two of 16 estrous periods. Mean +/- SE standing time (during the nine-hour nightly observation period) for heifers and cows was 148 +/- 6.8 and 278 +/- 9.6 (P < 0.01) minutes, respectively. The prevalence of bellowing was very low and not always associated with estrus. These results indicate that standing time, number of position changes, and bellowing are rather weak indicators of estrus.

Effect of gonadotrophin releasing hormone on conception rate in repeat-breeder dairy cows.

The effect of gonadotrophin releasing hormone (GnRH) on conception rate was studied in 961 repeat-breeder cows in five California dairy farms. Cows were injected with GnRH or saline at the time of the fourth insemination. All breeding was by artificial insemination (AI) using frozen semen from two bulls. Conception rate for GnRH-treated cows was higher than for controls (47.0 vs 37.7%, P < 0.01). There was no significant difference in conception rate between the two bulls or among five AI technicians. How GnRH acts upon fertility in repeat-breeder cattle has not been determined.

Uterine motility in the cow during the estrous cycle. I. Spontaneous activity.

This study describes a method for measuring intrauterine pressure (IUP) changes and uterine motility in cows. Spontaneous uterine motility was recorded during the estrous cycle in stanchioned, nonlactating dairy cows using a pair of miniature pressure transducers mounted 15 cm apart at the distal end of a dacron catheter placed in one uterine horn via the cervix. Clinical examination of ovarian status and determination of the peripheral plasma levels of estradiol-17beta and progesterone were used to determine the stages of the cycle. The pressure sensors recorded variations in muscular resting tension (tone) and the occurrence, spatial distribution, and force of the uterine contractions. Both tone and uterine activity varied significantly during the cycle. They were minimal during diestrus, increased during proestrus, reached maximal values at estrus, and then decreased. The highest synchronized motor activity with presence of peristaltic-antiperistaltic movements occurred during estrus. The prevailing direction of the uterine contractions during late estrus (immediate preovulatory period) was cervico-tubal.

Uterine motility in the cow during the estrous cycle. III. Effects of oxytocin, xylazine, and adrenoceptor blockers.

Intrauterine pressure (IUP) was recorded in nonlactating dairy cows using an intraluminal catheter with two micropressure transducers located 15 cm apart at the distal end. There was a significant increase (P < 0.05) in IUP following administration of xylazine and oxytocin at all four stages of the estrous cycle. The most significant increase in IUP occurred during proestrus for both drugs. The effect of pretreatment with adrenoceptor-blocking agents on IUP changes induced by xylazine and oxytoxin was evaluated. Alpha-1 adrenoceptor blockade (prazosin) had no effect on IUP following xylazine treatment. However, alpha-2 adrenoceptor blockade (yohimbine) resulted in a reduction (P < 0.05) in IUP compared to controls. Neither prazosin or yohimbine affected oxytocin-induced IUP.

Collection and phagocytic evaluation of uterine neutrophilic leukocytes.

The study of phagocytosis in the bovine uterus requires the collection of large numbers of uterine leukocytes. A method of stimulating polymorphonuclear neutrophil (PMN) invasion into the bovine uterus with oyster glycogen was tested. Following glycogen treatment, uterine aspirates contained large numbers (10(6)-10(9)) of viable uterine PMN. In Experiment 1, six cows were treated at one-week intervals by intrauterine infusion with 0.1, 1.0 and 10.0% oyster glycogen, respectively. Uterine lumens were lavaged at 0, 12, 24, 48, 72 and 168 hours post-infusion with each concentration of glycogen. The mean peak response for PMN was at 12 hours post-infusion of glycogen. In Experiment 2, uterine and peripheral blood PMN were collected from each of 12 cows. Phagocytosis was measured as the percent of (32)Phosphorus-labeled Staphylococcus aureus ingested by PMN during a one-hour incubation. Mean (+/- standard deviation) percent phagocytosis was not statistically different between blood (53.6 +/- 11.0%) and uterine (43.8 +/- 13.0%) PMN. This indicates that phagocytic activity was similar for PMN collected either from the uterine lumen or peripheral blood.

Incidence and treatments of postpartum reproductive problems in a dairy herd.

Incidence of assisted births, retained fetal membranes (RFM), and metritis were recorded in one hundred dairy cows from parturition through 14 days post-calving. Manual removal of RFM was not attempted. All RFM were excised inside the vulva and observations of natural RFM expulsion were recorded. Fifteen of 100 cows (15%) had assisted births, 27 (27%) had RFM, 8 (8%) had primary metritis not associated with other postpartum reproductive problems, and 26 (26%) had secondary metritis. Uterine swabs for culture were collected during the study from cows with postpartum reproductive problems. E . coli was the most common organism isolated (69.4%). Sensitivities of all isolates to penicillin, tetracycline, and triple sulfa were 44.0%, 59.5%, and 36.9% respectively. One of two antibiotic treatments were administered to cows with these postpartum reproductive problems. Treated animals received either 5 g. tetracycline powder IU on day 1 of treatment plus 10.5 million units procaine penicillin G IM on days 1, 2, and 3; or 4 Sulfaurea boluses IU on day 1. Despite the antibiotic treatments, 26 of 34 cows having either assisted birth and/or RFM developed metritis (76%). Neither treatment regimen was superior to the other. The poor results of antimicrobial therapy suggested the futility of routine administration of therapeutic agents for postpartum reproductive problems. Treatment failure was attributed to ineffective drugs or inadequate dosage regimens.

Phagocytosis in the uterus: A review.

Phagocytosis is an important non-specific defense mechanism. Uterine phagocytosis is reviewed emphasizing factors which may alter the uterine phagocytic responses including the estrous cycle, pregnancy and the puerperium, and the presence of an intrauterine device. Implications of phagocytosis in therapy of and recovery from intrauterine infections are considered.

Effects of intrauterine challenge with Leptospira interrogans serovar hardjo on fertility in cattle.

The purpose of this study was to determine the effects of Leptospira interrogans serovar hardio on fertility in cattle. Twenty seronegative mature dairy cows were assigned to two groups. Group I (challenged cows) was bred by a seronegative bull followed by intrauterine infusion (within 30 minutes) of Leptospira interrogans serovar hardjo. Group II was bred by the same bull followed by intrauterine infusion of 5 ml of sterile culture medium. Blood samples were collected at two-day intervals to monitor serum antibody titers. Daily blood cultures for 10 days and weekly urine cultures for five weeks were performed to monitor the animals for leptospiremia and leptospiuria. Cows were slaughtered 35 days post-breeding, and their reproductive tracts were examined. All animals remained clinically normal following intrauterine challenge. There was no difference in pregnancy rates (Group I, 7/10; Group II, 6/10). All embryos, reproductive tracts, and kidneys appeared normal. A microscopic agglutination test (MA) showed that 4 of 10 challenged cows developed serum antibody titers between 8 and 20 days after challenge. However, on the basis of the hamster passive protection test, all challenged cows had serum antibodies present. All blood and urine cultures were negative through the experimental period, as were the final kidney and uterine cultures. In a second experiment, six seronegative cows were infused with killed microorganisms immediately after insemination. Results of a microscopic agglutination test and a hamster passive protection test indicated that these cows did not develop humoral antibodies against serovar hardjo. These results indicated that intrauterine inoculation of Leptospira interrogans serovar hardjo (hamster-adapted strain) following breeding did not affect pregnancy rates despite an intrauterine challenge which caused the development of humoral antibodies.

Uterine motility in the cow during the estrous cycle. II. Comparative effects of prostaglandins F(2alpha), E(2), and cloprostenol.

Intrauterine pressure (IUP) changes were recorded in nonlactating, cyclic dairy cows using transcervically placed intraluminal pressure microtransducers. Spontaneous activity was recorded for the first 30 min. Prostaglandins (PG) F(2alpha) (5 mug/kg), E(2) (5 mug/kg), or cloprostenol (0.1 mug/kg) were then injected intravenously (i.v.) at diestrus, proestrus, estrus, and metestrus, and their effects were recorded. The drug administrations did not alter the duration of the estrous cycle of the cows. Single doses of PGF(2alpha) and E(2) significantly increased uterine activity at all stages of the estrous cycle, while cloprostenol had no effect. PGF(2alpha) and PGE(2) increased IUP, frequency, and amplitude during all stages of the estrous cycle. The spontaneous pattern resumed within 20 min postinjection. Partial uterine refractoriness occurred with both PGs. The results indicate that low doses of natural prostaglandins stimulate uterine activity during the estrous cycle in cattle.

Evaluation of beta-endorphin and naloxone on bovine uterine motility.

Effects of beta-endorphin and naloxone on bovine uterine motility were tested both in vivo and in vitro. Six cyclic Holstein cows were used to study in vivo effects of beta-endorphin and naloxone on uterine motility during estrus and diestrus. Intrauterine pressure changes were recorded by a microtip pressure transducer before and after treatment. Blood samples were taken every 10 min during the recording periods for beta-endorphin assay. The results revealed that beta-endorphin anc naloxone had no effect on intrauterine pressure in vivo. The effects of beta-endorphin and naloxone on myometrial contractility were also examined in vitro. Beta-endorphin and naloxone were added to tissue baths containing estrous and diestrous uterine strips. The results showed no significant effect of beta-endorphin and naloxone on bovine myometrial contractility. The role of beta-endorphin in bovine reproductive physiology is still not clearly understood, and additional studies are needed.

Effects of estradiol cypionate and natural and synthetic prostaglandins on myometrial activity in early postpartum cows.

The objectives of this experiment were to compare the effects of prostaglandin F(2alpha) (PGF(2alpha)) and its synthetic analogue treatment on postpartum bovine myometrial activity with and without estrogen priming. Sixteen multiparous, normal postpartum Holstein cows were randomly assigned to the following four treatment groups: saline PGF(2alpha), cloprostenol and fenprostalene. Myometrial activity was recorded using a catheter containing a miniature pressure transducer placed in the previously gravid horn via the cervix. Spontaneous myometrial activity was recorded at 48 h post partum for 60 min in all cows. Saline (5 ml,i.m.), PGF(2alpha) (25 mg,i.m.), cloprostenol (500 ug,i.m.) or fenprostalene (1 mg, s.c.) was administered to the cows according to the group. Myometrial activity was recorded until it returned to baseline. At the end of myometrial activity recording, 10 mg of estradiol cypionate (ECP) was injected i.m. to each cow. The same treatment schedule was repeated 12 h later. Results from this study indicate that PGF(2alpha) or its analogues, with or without ECP priming, do not increase myometrial activity in the postpartum cow. After ECP administration, both spontaneous and drug-induced myometrial activity increased; however, this increased myometrial activity was not statistically significant.

Demonstration and quantitation of immunoglobulins in bovine serum, follicular fluid, and uterine and vaginal secretions with reference to bovine viral diarrhea and infectious bovine rhinotracheitis.

Immunoglobulin concentrations (IgG, IgM, and IgA) in bovine serum, follicular fluid, and uterine and vaginal secretions were determined. The specificities of IgG, IgM, and IgA for virus-neutralizing antibody against bovine viral diarrhea (BVD) and infectious bovine rhinotracheitis (IBR) viruses were also examined. High concentrations of IgG were present in both serum and follicular fluid. The IgG, IgM, and IgA concentrations were low in uterine and vaginal secretions. There was more IgG in the uterus during estrus than at any other time. Virus-neutralizing antibodies against BVD and IBR in serum of cows were mainly the IgG class. There was positive correlation between serum and follicular fluid virus-neutralizing antibody titers fro BVD and IBR. These antibodies may provide some protection for recently ovulated ova.

Role of blood cells in degradation of progesterone in bovine blood.

The nature of progesterone decline in samples of bovine blood as affected by whole blood incubation time and temperature was investigated in 3 experiments. In 2 experiments, progesterone concentrations were determined in plasma, in hemolyzed (by freezing and thawing) blood, and in washed blood cells and blood cell washes before and after 8 hours of incubation at 22 C to study the effect of RBC on detected progesterone. In the third experiment, the effect of alteration in RBC metabolism on progesterone degradation by these cells was studied by using potassium oxalate-sodium fluoride as anticoagulant. Results of these experiments indicated that (a) progesterone was significantly reduced because of whole blood incubation time and temperature, (b) lost progesterone was not detectable on or in blood cells indicating chemical degradation of progesterone, (c) intact blood cells were needed to obtain the decrease in the progesterone, (d) a small amount of circulating blood progesterone was associated with blood cells, and (e) degradation of bovine blood progesterone by blood cells was dependent on the glycolytic process. Potassium oxalate-sodium fluoride anticoagulant and refrigeration provided the best progesterone results when blood samples were not processed immediately after collection.

Decline in assayable progesterone in bovine plasma: effect of time, temperature, anticoagulant, and presence of blood cells.

Jugular vein blood samples collected from 5 Holstein-Friesian cows during the luteal phase of the estrous cycle were incubated at 4 C, 22 C, and 37 C for 0, 0.5, 1, 2, 4, 6, 8, 12, and 24 hours. Blood samples were centrifugated after each incubation period, and plasma was frozen for later progesterone assay. Mean progesterone concentration in blood samples incubated at 4 C, 22 C, and 37 C decreased from 5.7 ng/ml at 0 hour to minimum concentrations of 3.5 ng/ml at 12 hours, 0.9 ng/ml at 12 hours, and 1.0 ng/ml at 8 hours, respectively. The first progesterone concentration which was significantly different from the initial value (0 hour) was at the 8-hour incubation period for blood samples incubated at 4 C and at the 1-hour incubation period for blood samples incubated at 22 C and 37 C. Progesterone concentration decreased similarly when blood samples were collected into heparinized tubes or EDTA tubes and incubated at 22 C for 0, 6, and 12 hours. Incubating harvested plasma or serum for 0 to 6 hours at 37 C had no effect on progesterone concentrations (7.9 and 8.2 ng/ml for plasma, and 6.9 and 6.6 ng/ml for serum.

Effect of chlorpyrifos on Holstein steers and testosterone-treated Holstein bulls.

The effect of chlorpyrifos application was studied in a high-testosterone (testosterone-treated bulls) and a low-testosterone group (corn oil-treated steers). Frequent sampling of blood before and after 2 chlorpyrifos applications was used to monitor plasma testosterone concentrations and blood cholinesterase activities. Bulls had significantly higher testosterone concentrations (P less than 0.01) than did the steers, before and after the 1st and 2nd chlorpyrifos applications. Bulls had higher cholinesterase activities (P less than 0.01) than did steers before the 1st chlorpyrifos application. However, cholinesterase activity decreased more in bulls when compared with that in steers (P less than 0.01) after the 1st and 2nd chlorpyrifos application. Abnormal clinical signs were not observed in the steers, but 2 of 4 bulls had severe clinical signs of organophosphorus insecticide toxicosis after the 2nd application. Seemingly, chlorpyrifos is more toxic for testosterone-treated bulls than for corn oil-treated steers of similar age and weight.

Endotoxin-induced bovine mastitis: immunoglobulins, phagocytosis, and effect of flunixin meglumine.

Milk whey immunoglobulins (Ig) and phagocytosis of staphylococci by milk polymorphonuclear neutrophilic leukocytes (PMN) were measured in 12 cows (allotted to 6 pairs) during acute bovine mastitis induced by intramammary inoculation of endotoxin. Six of these cows (or 1 in each pair) were treated with flunixin meglumine and were compared with the others (given only saline solution). The endotoxin inoculation comprised 10 micrograms of Escherichia coli O26:B6 lipopolysaccharide injected into one of the rear quarters (mammae). Flunixin meglumine was administered parenterally at a dosage of 1.1 mg/kg every 8 hours (total of 7 doses) beginning at 2 hours after endotoxin was injected. Milk samples were obtained, and whey samples were prepared from each quarter of each cow 3 times before inoculation and at 2, 4, 8, 12, 24, 48, 72, 96, 120, 144, 168, and 336 hours after endotoxin was inoculated. Significant increases (P less than 0.05) in milk whey IgG1, IgG2, IgM, and IgA concentrations were observed in whey samples from endotoxin-inoculated quarters. Greatest relative increase was seen for IgG2. Increased whey Ig concentrations were not observed in quarters which were not inoculated with endotoxin. Concentrations of whey IgG1 and IgM in endotoxin-inoculated quarters were significantly (P less than 0.05) decreased in flunixin meglumine-treated cows, compared with those in saline solution-treated cows. Significant increases in phagocytosis of staphylococci by milk PMN were observed in whey samples from endotoxin-inoculated quarters. Significant differences in PMN phagocytosis were not found in whey samples from cows given flunixin meglumine when compared with whey samples from cows given saline solution.

Influence of the estrous cycle on selected biochemical and cytologic characteristics of milk of cows with subclinical mastitis.

The purpose in this experiment was to determine the relationship between subclinical mastitis and the estrous cycle. Subclinical mastitis was defined as a quarter in which milk had a somatic cell concentration greater than 500,000/ml and was bacteriologic culture-positive on 2 consecutive examinations. Normal quarters were defined as quarters from which milk had a somatic cell concentration less than 500,000/ml and was bacteriologic culture-negative on 2 consecutive examinations. Selected biochemical and cytologic characteristics of milk from 10 cows with subclinical mastitis were measured at 5-day intervals during the estrous cycle. Milk and blood progesterone concentrations were determined. Analysis of variance of dependent variables was performed, using a model with the following factors: cows, treatments, days of estrous cycle, and interaction of treatment with day of the estrous cycle. Treatment consisted of comparison of normal and subclinically mastitic quarters. Clinical signs of mastitis tended to occur more often during estrus (days 0 and 20) than during diestrus (day 10). Day of the estrous cycle was a significant source of variation for bovine serum albumin concentrations in milk. Somatic cell concentrations, electrical conductivity, milk bacterial concentrations, and log10 milk bacterial concentrations did not vary significantly during days of the estrous cycle. A significant treatment-by-day interaction occurred for milk progesterone concentrations; blood progesterone concentrations were not similarly affected. Milk progesterone concentrations for mastitic and normal quarters were similar at estrus (days 0 and 20) and metestrus (day 5). Milk progesterone concentrations for mastitic quarters were significantly decreased on day 15 of the estrous cycle, compared with values from normal quarters.

Effects of endometrial biopsy, uterine culture, and cervical dilatation on the equine estrous cycle.

In 10 mares, lysis of the corpus luteum was induced by endometrial biopsy and culture on day 4 after estrus, as evidenced by a sharp decline in serum progesterone concentration and a shortened interestrous interval. Estrus following the manipulations was prolonged. Endometrial biopsy and culture on days 1 and 3 after estrus or manually dilating the cervix on day 4 after estrus also decreased the serum progesterone concentration (within 24--48 hr after manipulation), shortened diestrus, and prolonged the subsequent estrus. In a 2nd experiment, endometrial biopsy on day 4 after estrus shortened the estrous cycle and diestrous period and prolonged the subsequent estrus. It was postulated that these manipulations stimulated corpus luteum regression, followed by estrus and ovulation in the mare.

Uterine tube abnormalities in cattle.

A total of 250 reproductive tracts from nonpregnant cows were obtained from a slaughterhouse. Uterine tubes were tested for patency by infusing methylene blue solution, and gross lesions were recorded. Of the 500 uterine tubes, 24 were occluded (unilateral in 20 tracts and bilateral in 2 tracts), and 26 had gross lesions (unilateral in 16 tracts and bilateral in 5 tracts). Approximately one-half of the occluded tubes were not associated with gross lesions. Approximately one half of the tubes with gross lesions were patent.

Greater participation by veterinarians in the reproductive management of dairy cattle.

A program involving greater veterinary participation in detection of estrus and artificial insemination of cattle was evaluated in a 700-cow dairy herd from January 1987 through August 1988. Previous reproductive performance was below normal. First-service pregnancy rate from artificial insemination was 42%, and mean number of nonpregnant days for the cows was 120. Between postpartum days 55 and 62, all cows with functional corpus luteum assessed by rectal palpation were administered prostaglandin each Monday morning. Return visits were made to the herd each Thursday and Friday to observe cows and to inseminate those in estrus. On the other 5 days of the week, the owner or his employees inseminated all cows in estrus. The first-service pregnancy rate for 842 cows observed in estrus and inseminated by the veterinarian was 59%. The pregnancy rate for cows inseminated by the owner and his employees increased from 42% to 50%. The mean number of nonpregnant days for all 700 cows decreased from 120 to 98 days, resulting in approximately $46,000 of increased income for the dairyman or approximately a 4 to 1 return on investment in veterinary service. Results indicate that veterinarians could improve herd reproductive performance and solve chronic herd breeding problems by more actively participating with their clients in estrus detection and artificial insemination programs in cattle. The program allows practicing veterinarians an opportunity to observe cows for estrous behavior, establish their own pregnancy rate data, demonstrate to owners the importance of observing primary signs of estrus, and teach expert artificial insemination techniques.