A review of 126 Caesarean sections by blood gas and the acid-base status of newborn calves

Blood gas and acid-base status was determined in 126 Caesarean-derived calves. The newborn calves were assigned by venous blood pH value at birth to three groups as follows: Group 1 (normal): pH above 7.2; Group 2 (slight acidosis): pH 7.2 to 7.0; and Group 3 (severe acidosis): pH below 7.0. Following Caesarean section births 80 (63.5%) calves had normal acid-base values, while 30 (23.8%) had a slight acidosis, and 16 (12.7%) had severe acidosis. The degree of hypoxia was similar in each group. Six calves (37.5%) in Group 3 died within 48 h of birth. The blood gas and acid-base status of Caesarean-derived. calves was not significantly influenced by any examined parameters with the exception of sex in Groups 1 and 2. The occurrence of meconium-stained calves was 9.1% (n = 11), and only two calves were slightly or severely acidotic immediately after birth.     

The effect of irregular feeding times on the behaviour and growth of dairy calves

The objective of this study was to examine the effects of predictable vs. unpredictable management routines on the behaviour, production and health of dairy calves. Three different feeding schedules for milk-fed dairy calves were compared. All calves received milk twice a day, and had free access to concentrate, hay and water. Three groups of 12 calves (divided on two trials) were exposed to one of the following treatments from the age of 5 days to 9 weeks: group C (control) received milk at the same time every day, at 0700 and 1400. Group OD (occasional deviation) received the milk at the same time every day except on treatment days, one in week 5 and one in week 8, where they were fed 3 h later. Group IR (irregular schedule) received milk at irregular times throughout the experimental period. The first daily feeding took place between 0600 and 1300 and the second one between 1300 and 2100. When the calves were 5 and 8 weeks old, the behaviour of eight calves from each group was videorecorded for two days (48 h). The following behaviour was recorded: frequency and duration of lying bouts and frequency of comfort behaviour (defined as licking or scratching own body), eating, drinking, other oral behaviour and extending the head through the feeding barrier (HTB). The milk and concentrate consumption of the calves was measured and the calves were weighed weekly. Diseases were recorded.The results showed that at the age of 5 weeks, the calves in group IR differed from the control group C by performing more eating behaviour both on the control day (27.5 vs. 15.5; p<0.05) and the treatment day (28.8 vs. 18.3; p<0.05). At the age of 8 weeks, no differences were found in the behaviour between groups IR and C. When the OD calves were 5 weeks old, they responded to the delayed feeding by increasing drinking behaviour (14.5 vs. 9.0; p<0.05). When they were 8 weeks old, they showed increased frequency of comfort (195 vs. 122; p<.05), eating (37.5 vs. 27.9; p<0.05) and HTB behaviour (19.8 vs. 7.4; p<0.001) on the treatment day compared to the control day. The IR group did not respond to the same treatment except for a slight increase in drinking behaviour (9.6 vs. 6.5; p<0.05) at the age of 8 weeks. No differences were observed in the frequency or length of lying bouts, nor health or production parameters between the three groups.It is concluded that a predictable feeding schedule may not be very important for milk-fed dairy calves. However, when the calves are customised to predictable feeding times, occasional deviations from that schedule may cause frustration when their expectations are not fulfilled.     

Comparison of three commercial vaccines for preventing persistent infection with bovine viral diarrhea virus

Eighty crossbred beef heifers were randomly allocated to four groups to evaluate the efficacy of vaccination in preventing development of calves persistently infected with bovine viral diarrhea virus (BVDV). Group 1 (n = 11) was non-vaccinated controls, whereas three groups were vaccinated with commercially available multivalent BVDV vaccines at weaning (∼7 mo of age), 28 d post-weaning, ∼1 y of age, and 28 d later. Groups 2 (n = 23) and 3 (n = 23) were given a modified-live BVDV vaccine, whereas Group 4 was given an inactivated BVDV vaccine. Heifers were bred by AI and subsequently exposed to two bulls. At 61 d after AI, 70 heifers were pregnant (n = 10 for Group 1 and n = 20/group for Groups 2, 3, and 4). Three cattle persistently infected with BVDV were commingled with the pregnant heifers (in an isolated pasture) from 68 to 126 d after AI. Thereafter, viremias were detected in pregnant heifers from Groups 1, 3, and 4 (10/10, 1/20, and 10/20, respectively), but not in pregnant heifers from Group 2 (0/20). Resulting calves were assessed for persistent infection using serum PCR, ear notch antigen capture-ELISA, and immunohistochemistry. Persistently infected calves were only produced in Group 1 (10/10) and Group 4 (2/18). In conclusion, commercial vaccines provided effective fetal protection despite prolonged natural exposure to BVDV. Given that viremias were detected in 11 vaccinated heifers after BVDV exposure, and two vaccinated heifers gave birth to persistently infected calves, there is continued need for biosecurity and diagnostic surveillance, in addition to vaccination, to ensure effective BVDV control.     

Effects of management at weaning on behaviour and weight gain of farmed red deer calves

Two studies were performed to determine whether there were behavioural or productive differences arising from two contrasting weaning practices for red deer; proximate vs. distant separation of dams and calves. In Experiment 1, 80 calves across two replicates were used. For each replicate, calves were separated from their mothers, weighed and allocated to one of two treatments (n=20 calves), either confinement in an unfamiliar paddock 100 m from their mothers for 2 weeks following weaning (treatment N), or transportation 2 km to a different farm (treatment F). Groups were observed during the following 6 days and weighed 14 days after weaning. In Experiment 2, the same procedure was performed out on two commercial farms, but using 40 calves per treatment group, without replication or weight recording. In Experiment 1 running, fenceline pacing and vocalising declined following weaning, with steeper declines for F than N calves for running and vocalising (P<0.01). Similar trends, with an indication of less vocalising and movement overall, were seen in Experiment 2. In contrast, mean post-weaning weight gains for N calves were higher than for F calves (3.0 compared with 2.4 kg, SED 0.48 kg; P<0.05). Weather variables (cloud, temperature and wind) were associated with behaviour in both studies (P<0.05), with a trend for pacing, calling and running to increase as conditions deteriorated (cloud cover and wind speed increased, and temperature decreased). It was concluded that distant separation appeared beneficial to the calves but more research was required to determine optimal weaning management. The study supported previous evidence that weaning should be carried out in good weather.     

Induction of twinning in crossbred heifers by ipsilateral frozen embryo transfer

Induction of twinning by means of nonsurgical ipsilateral transfer of two frozen embryos or of demi-embryos was attempted in 297 virgin crossbred dairy heifers that were kept at the following locations: in stables at our breeding station (Group 1), in a mountain field (Group 2) and at a private farm (Group 3). Of these, 187 heifers (63%) were diagnosed pregnant at 25 d after embryo transfer and 134 heifers (45%) were diagnosed pregnant at 60 d after transfer by ultrasonic echography or by palpation per rectum. At calving, 118 heifers produced 46 sets of twins and 72 single calves, for a total of 164 calves sixteen pregnant heifers aborted fetuses between 2 and 7 mo. The pregnancy rate of Group 1 (39%) was lower than that of Group 2 (48%) or Group 3 (50%). Abortion and mortality rates for Group 3 (8% and 8%, respectively) were significantly lower (P<0.05) than for Group 1 (16% and 12%) or Group 2 (13% and 18%). Twin calves had lower birth weights (P<0.05) than singles, but at 270 to 330 d of age, there was no significant difference between the weights of single and twin calves. Dystocia or difficult delivery was not observed heifers producing twins. Retention of the placenta was observed in twin calving heifers, with placenta retention levels the highest in Group 2 (33%) than followed by Group 1 (14%) and Group 3 (10%). When gestation periods were compared between single and twin calves in Groups 1 and 2, the gestation period of single calves was 5.0 to 7.0 d shorter than that of twin calves. No significant difference was observed between the gestation periods of single and twin births in Group 3.     

The effects of perphenazine and bromocriptine on follicular dynamics and endocrine profiles in anestrous pony mares

Nineteen anestrous pony mares were used in a project designed to determine the effects of altered prolactin concentrations on follicular dynamics and endocrine profiles during spring transition. The dopamine antagonist, perphenazine, was administered daily to mares (0.375 mg/kg body weight) in Group A (n = 6), while Group B mares (n = 7) received 0.08 mg/kg metabolic weight (kg75) dopamine agonist, 2-bromo-ergocriptine, intramuscularly twice daily. Mares in Group C (n = 6) received 0.08 mg/kg75, i.m., saline twice daily. Treatment began January 20, 1994, and continued until ovulation occurred. Mares were teased 3 times weakly with an intact stallion. The ovaries of the ponies were palpated and imaged weekly using an ultrasonic B-mode unit with a 5 Mhz intrarectal transducer until they either exhibited estrual behavior and had at least a 20-mm follicle, or had at least a 25-mm follicle with no signs of estrus. At this time, ovaries were palpated and imaged 4 times weekly. Blood samples were obtained immediately prior to ultrasonic imaging for measurement of prolactin, FSH and estradiol-17 beta. Perphenazine treatment advanced the spring transitional period and subsequent ovulation by approximately 30 d. Group A exhibited the onset of estrual behavior earlier (P < 0.01) than control mares. In addition, Group A mares developed large follicles (> 30 mm) earlier (P < 0.01) than Group B mares, with least square means for Groups A and B of 47.0 +/- 8.8 vs 88.1 +/- 8.2 d, respectively. Control mares developed 30-mm follicles intermediate to Groups A and B at 67.3 +/- 8.8 d. Bromocriptine decreased (P < 0.05) plasma prolactin levels throughout the study, while perphenazine had no significant overall effect. However, perphenazine treatment did increase (P < 0.05) mean plasma prolactin concentrations from Day 31 to 60 of treatment. There were no differences in mean plasma FSH or estradiol-17 beta between treatment groups. We concluded that daily perphenazine treatment hastened the growth of follicles and subsequent ovulation while bromocriptine treatment appeared to delay the growth of preovulatory size follicles without affecting the time of ovulation.     

The presence of the dam during handling prevents the socialization of young calves to humans

The effect of handling and hand-feeding of calves with or without their dams present on the calves’ subsequent response to humans was investigated using 5 groups of 10 Danish Friesian calves, each of which received a different treatment. The treatments were: calf separated from its dam immediately after birth, housed in a single pen and handled (group SH) or not handled (group S) calf adjacent to cow and handled (group CH) or not handled (C) for the first 4 days after calving. The fifth group was housed together with their dams for the first 4 days of life and then moved to single pens and handled there for the next 4 days (group C-SH). The handling treatment was carried out three times daily for 4 days and consisted of 6 min of hand-feeding with milk from a teat-bucket and patting, stroking and talking to the calf. After separation, all calves were housed in single pens. Human contact was minimised except during the treatment periods.

The approach behaviour of each calf to an unknown person was tested at days 20, 40 and 55 in their home pen. Flight distance was determined at day 55. The test at day 55 was carried out in a large single pen where the calves had been housed for 24 h prior to the test. The latency to interact (in seconds) with the person was significantly shorter (P<0.001) in all three tests for SH (13±5, 29±7 and 44±8, at days 20, 40 and 55, respectively) and C-SH (28±6, 47±17 and 70±17) compared to S (240±25, 238±33 and 173±5), C (240±28, 202±36 and 167±13) and CH (233±36, 271±29 and 128±19). The results of the latter three groups did not differ significantly. Treatment also affected the position and the orientation of the calf in the pen during the tests. Calves in SH and C-SH stood at the front of the pen and faced the person more often than calves in S, C and CH. Again, there were no significant differences between the results of the latter three groups.

The results indicate that the presence of the dam limits the effect of the handling treatment on young calves’ motivation to interact with humans. It is likely that primary socialization occurs with the dam, preventing a secondary socialization developing with humans, until the calf is isolated from the dam.     

Occurrence of a non-cellular suprazonary layer in embryos collected from prepuberal calves

Twenty Angus calves between 4 and 7 months of age were randomly assigned to one of two superovulation treatment groups. Group I consisted of ten calves which were injected intramuscularly with 50 mg of progesterone 4 and 2 days before injection with 1200 I.U. of PMSG followed 72 hrs later by 50 mg of LH given intravenously. Group II consisted of ten calves which were not injected with progesterone before receiving PMSG and LH as in Group I. Both groups of calves were inseminated by the rectal fixation method with two straws of frozen semen 72 hrs after PMSG injection and at subsequent 12 hr intervals for a total of four inseminations. All semen was extended from a single ejaculate from one bull. Embryos were recovered by surgery or slaughter 48 to 72 hrs following the last insemination. A total of 80 and 70 ovulations were recorded from treatment Group I and II, respectively. Recovery and fertilization rates were 66 and 57% following progesterone treatment and 67 and 51% in calves without progesterone pretreatment. Seventy-seven percent ($\text{23}\text{30}$) of the fertilized embryos recovered in treatment Group I exhibited a suprazonary layer. This suprazonary layer appeared to be non-cellular on the basis of eosin-hematoxylin staining and ranged in thickness from 3 to 24 μm. All fertilized embryos in treatment Group II and unfertilized eggs in treatment Groups I and II, possessed completely smooth zonae pellucidae with no evidence of a suprazonary layer. These observations suggest that the conditions of the progesterone treated prepuberal tract, coupled with the process of sperm penetration of the oocyte, result in the formation of a non-cellular layer which surrounds the zona pellucida to varying degrees of thickness. The influence of this suprazonary layer on embryo viability in prepuberal calves remains to be determined.     

Ovariectomy as a means of abortion and control of estrus in feedlot heifers

Three hundred and six heifers were randomly assigned to treatment groups in a three by six factorial design. Treatments were ovariectomy, melengestrol acetate (MGA), manual abortion, intramuscular estradiol cypionate (ECP) or Prostaglandin F2alpha and untreated controls. The Average Daily Gain (ADG) of the Ovariectomized Group was less (p < .01) during the first 24 days and not different (p > .05) for the total feeding period. Feed intake of the Ovariectomized Group was less (p < .05) than Manual Abortion, Prostaglandin or Control Groups during the first 24 days but essentially the same (p > .05) for the total period. The Prostaglandin Group required fewer days to reach slaughter condition than the Ovariectomy or MGA Groups (p < .05). The only difference in the cost/benefit analysis was in the direct cost of the treatments. Factors other than the various treatments interrupted many pregnancies. The effects of treatments varied with 100% of pregnancies terminated only in the Prostaglandin F2alpha Group.     

Field trial evaluating the influence of prophylactic and therapeutic antimicrobial administration on antimicrobial resistance of fecal Escherichia coli in dairy calves

The objective of this study was to describe the influence of in-feed and therapeutic antimicrobials on resistance in commensal fecal Escherichia coli isolated from preweaned calves. Four groups of 30, day-old calf-ranch calves were enrolled and raised until 4 weeks of age. Groups 1 to 3 were raised without antimicrobials in the feed. Group 1 was isolated from the other groups and received no antimicrobial therapy. Group 2 was housed on the calf ranch and did not receive antimicrobial therapy, whereas groups 3 and 4 could be treated with antimicrobials. Group 4 was fed neomycin and tetracycline HCl in the milk replacer. Fecal samples were collected from calves on days 1, 14, and 28. Three E. coli isolates per sample were evaluated for susceptibility to 12 antimicrobials. Cluster analysis was used to group isolates having similar susceptibility patterns. Cumulative logistic regression was used to evaluate factors associated with increasing levels of multiple antimicrobial resistance. In-feed antimicrobials were associated with higher levels of multiple antimicrobial resistance in fecal E. coli.f In calves not receiving in-feed antimicrobials, older calves had higher levels of resistance compared to day-old calves. Individual antimicrobial therapy increased resistance in these calves but appeared to be transient. There was no environmental influence on resistance in E. coli populations among study groups.     

Assessment of behavioral changes associated with oral meloxicam administration at time of dehorning in calves using a remote triangulation device and accelerometers

ABSTRACT: BACKGROUND: Dehorning is common in the cattle industry, and there is a need for research evaluating pain mitigation techniques. The objective of this study was to determine the effects of oral meloxicam, a non-steroidal anti-inflammatory, on cattle behavior post-dehorning by monitoring the percent of time spent standing, walking, and lying in specific locations within the pen using accelerometers and a remote triangulation device. Twelve calves approximately ten weeks of age were randomized into 2 treatment groups (meloxicam or control) in a complete block design by body weight. Six calves were orally administered 0.5 mg/kg meloxicam at the time of dehorning and six calves served as negative controls. All calves were dehorned using thermocautery and behavior of each calf was continuously monitored for 7 days after dehorning using accelerometers and a remote triangulation device. Accelerometers monitored lying behavior and the remote triangulation device was used to monitor each calf's movement within the pen. RESULTS: Analysis of behavioral data revealed significant interactions between treatment (meloxicam vs. control) and the number of days post dehorning. Calves that received meloxicam spent more time at the grain bunk on trial days 2 and 6 post-dehorning; spent more time lying down on days 1, 2, 3, and 4; and less time at the hay feeder on days 0 and 1 compared to the control group. Meloxicam calves tended to walk more at the beginning and end of the trial compared to the control group. By day 5, the meloxicam and control group exhibited similar behaviors. CONCLUSIONS: The noted behavioral changes provide evidence of differences associated with meloxicam administration. More studies need to be performed to evaluate the relationship of behavior monitoring and post-operative pain. To our knowledge this is the first published report demonstrating behavioral changes following dehorning using a remote triangulation device in conjunction with accelerometers.     

Field Trial Evaluating the Influence of Prophylactic and Therapeutic Antimicrobial Administration on Antimicrobial Resistance of Fecal Escherichia coli in Dairy Calves

The objective of this study was to describe the influence of in-feed and therapeutic antimicrobials on resistance in commensal fecal Escherichia coli isolated from preweaned calves. Four groups of 30, day-old calf-ranch calves were enrolled and raised until 4 weeks of age. Groups 1 to 3 were raised without antimicrobials in the feed. Group 1 was isolated from the other groups and received no antimicrobial therapy. Group 2 was housed on the calf ranch and did not receive antimicrobial therapy, whereas groups 3 and 4 could be treated with antimicrobials. Group 4 was fed neomycin and tetracycline HCl in the milk replacer. Fecal samples were collected from calves on days 1, 14, and 28. Three E. coli isolates per sample were evaluated for susceptibility to 12 antimicrobials. Cluster analysis was used to group isolates having similar susceptibility patterns. Cumulative logistic regression was used to evaluate factors associated with increasing levels of multiple antimicrobial resistance. In-feed antimicrobials were associated with higher levels of multiple antimicrobial resistance in fecal E. coli.f In calves not receiving in-feed antimicrobials, older calves had higher levels of resistance compared to day-old calves. Individual antimicrobial therapy increased resistance in these calves but appeared to be transient. There was no environmental influence on resistance in E. coli populations among study groups.     

Effect of relaxin on facilitation of parturition in dairy heifers

Purified pig relaxin (3000 U/mg) was injected i.m. into pregnant Holstein dairy heifers on Day 276 or 277 to determine its effect on parturition and sequential measurements of the pelvic area, cervical dilatation, and peripheral blood-plasma concentrations of progesterone and relaxin. Treatments included phosphate-buffer saline (2 ml, Group C, N = 7), relaxin once (1 mg, Group 1R, N = 7), and twice (2 mg, 12 h apart; Group 2R, N = 7). Intervals (mean +/- s.e.) between the first injection of relaxin or PBS and calving were 64 +/- 17, 80 +/- 19 and 125 +/- 34 h for Groups 2R, 1R and C, respectively. The calving intervals were reduced in Groups 2R (P less than 0.01) and 1R (P less than 0.05) compared with Group C. The incidence of dystocia was 29% (2 of 7) in Group 2R and 43% (3 of 7) in Group 1R compared with 57% (4 of 7) in Group C (P less than 0.01). Body weights and ratios of males to females of the calves were similar (P greater than 0.05) between groups. Progesterone plasma concentrations decreased (P less than 0.01) earlier in Groups 1R and 2R compared with Group C, and this acute decrease began within 6 h of treatment. At 24 h after relaxin or PBS injection, progesterone concentrations were 2.7 +/- 1.1 ng/ml for Group 2R, 3.5 +/- 0.9 ng/ml for Group 1R, and 6.0 +/- 0.1 ng/ml for Group C. Relaxin reached peak blood-plasma levels of 19 +/- 2.2 ng/ml 1 h after injection of relaxin, but remained unchanged, 0.3 +/- 0.01 ng/ml, in Group C. Pelvic area was increased 26%, 22% and 14% and cervical dilatation was increased 109%, 76% and 53% 48 h after injection in Groups 2R, 1R and C, respectively, but these responses were similar among groups at the time of parturition. We conclude that two i.m. injections of relaxin facilitated earlier calving, acutely decreased progesterone secretion, increased cervical dilatation and pelvic area expansion, and decreased the incidence of dystocia in dairy heifers.     

Conception rates in dairy cows after timed-insemination and simultaneous treatment with gonadotrophin releasing hormone and/or prostaglandin F2 alpha

This study was designed to determine conception rates in dairy cows after timed-insemination and simultaneous treatment with gonadotrophin releasing hormone (GnRH) and/or prostaglandin F2 alpha (PGF2alpha). A total of 2352 cows was randomly assigned to six groups. Cows in Groups 1 to 5 were palpated per rectum to determine the presence of a corpus luteum (CL) on the ovary, and blood samples were obtained for the determination of plasma progesterone (P4) concentrations. Cows with a CL and P4 concentrations >1 ng/ml were treated (Day 0) with PGF2alpha (25 mg, i.m.) and were observed for estrus. Cows in estrus prior to 72 hours after treatment (Group 5, n = 106) were bred, but were not treated. Cows not observed in estrus by 72 hours were divided into four remaining groups, were bred between 72 and 80 hours and were assigned as follows: Cows in Group 1 (n = 203) were not treated; Cows in Group 2 (n = 200) were treated with GnRH (100 ug, i.m.); Cows in Group 3 (n = 201) were treated with PGF2alpha (25 mg, i.m.); and cows in Group 4 (n = 202) were treated with both GnRH and PGF2alpha. Cows in Group 6 (n = 1440) were not treated with PGF2alpha on Day 0 and were estrual cows that were bred on days when cows in Groups 1 to 5 were time-inseminated. The percentage of cows in all groups pregnant at 45 to 50 days after one insemination was compared using analysis of variance (P<0.05). The conception rate of cows in Group 2 was significantly higher than that of cows in Groups 1 to 4. There was a significant group-by-season interaction. Cows treated with GnRH during the spring had a higher conception rate than at other times of the year. Conception rates of cows in Groups 1 to 4 that were inseminated during the summer were low and not significantly different from each other. Conception rates of cows in Groups 5 and 6 inseminated during the summer were not significantly different from each other, but were significantly higher than that of cows in Groups 1 to 4 that were inseminated during the summer.     

Spectrum of in vivo and in vitro cell-mediated immune responses in coccidioidomycosis.

The cell-mediated immune responses of 12 healthy, coccidioidin skin-test positive subjects (Group I) were compared with those of 15 healthy, coccidioidin skin-test positive persons who had primary asymptomatic coccidiodomycosis, (Group II), 12 patients with active, pulmonary coccidioidomycosis (Group III), four patients with disseminated disease (Group IV), and five patients who had been in clinical remission for 1 year or longer (Group V). Lymphocytes from healthy subjects in Groups I and II responded in vitro to Coccidioides immitis antigen by undergoing an increased DNA synthesis (lymphocyte transformation) and/or by producing macrophage migration inhibitory factor (MIF). In contrast, patients in Groups III and IV failed to respond to Coccidioides antigens in vivo (skin tests) or in vitro (lymphocyte transformation and production of MIF). The responses of subjects in Group V with inactive disease fell in between those of healthy donors in Groups I and II and patients in Groups III and IV. The cellular immune defect, in terms of antigen recognition, appeared to be specific for C. immitis in all but one patient.     

The social environment influences the behavioural responses of beef cattle to handling

In cattle, a gregarious species, the social group influences individual stress responses to fear-eliciting situations. As handling can be stressful for farm animals, it can be hypothesised that social partners modify individual responses to handling. The present experiment investigated the effect of the presence or absence of social partners on behavioural reactions of beef calves in a handling test. At the age of 10 months, 38 calves from two breeds (Salers and Limousine) were individually subjected to the docility test, once while in visual contact with four familiar peers, and once in the absence of peers, following a crossover design. The docility test procedure included physical separation from peers (30 s; period 1), exposition to a stationary human (30 s; period 2), and handling by human (30 s-2.5 min, according to the success in handling; period 3). In absence of human (period 1), calves in visual contact with their peers spent more time motionless than when peers were totally absent (P<0.001). The social environment also influenced the duration of handling (period 3); the human required more time to successfully handle calves when peers were present (P<0.05). In conclusion, the presence of peers affects individual calves' reactions to the docility test.     

Aversion learning techniques to evaluate dairy cattle handling practices

Fear of humans is a source of stress for Holstein dairy cattle and can result when animals are handled aversively. We used aversion learning techniques to determine which handling practices cattle find most aversive. In an aversion race, the cows are repeatedly walked down a race and treatments applied when they reached the end; the time and force required for cows to walk down the race are measured. The animal learns to associate walking down the race with the treatment received; if the treatment is aversive, the animal will take more time and require more force to reach the end of the race than if the treatment is positive. In experiment 1, 54 cows were assigned to four treatments (hit/shout, brushing, control, and food). Treatments of 2-min duration were applied three times a day for 4 days. Cows on the hit/shout treatment took more time and required more force to walk through the race than cows on other treatments, while brushed cows took longer to move through the race than cows given food. In experiment 2, 60 cows were assigned to five treatments (electric prod, shouting, hitting, tail twist, and control). Treatments of 1-min duration were applied three times a day for 3 days. Cows on the shout and electric prod treatments took more time and required more force to walk down the race than cows on the control treatment. In experiment 3, thirty-six 1-1.5-year-old heifers were assigned to three treatments (hand feeding, gentling, or control) applied as in experiment 2. Treatments did not affect the time or force required to walk down the race. The aversion race successfully discriminated between handling treatments that differ greatly in aversiveness but lacked sensitivity to distinguish between treatments that were similar. Although many procedural factors must be considered, aversion learning techniques are an effective method to determine which handling practices cattle find aversive or rewarding.     

Induction and synchronization of ovulations of nulliparous and multiparous sows with an injection of gonadotropin-releasing hormone agonist (Receptal)

The objective of this study was to determine if administration of a set dose (10 μg) of a gonadotropin-releasing hormone agonist, buserelin (Receptal; Rc), at set times after altrenogest (Regumate; RU) treatment or after weaning was able to induce and synchronize ovulation in female swine (gilts and sows). The pubertal (n = 187) gilts were allocated to four groups, all synchronized with RU. Group 1 (RU) was inseminated twice at detected estrus, Group 2 (RU+Rc120) and Group 4 (RU+Rc104) received 10 μg Rc at 120 or 104 h after the end of RU treatment, respectively, and Group 3 (RU+eCG+Rc104) was treated with 800 IU equine chorionic gonadotropin (eCG) at 24 h and Rc 104 h after the end of RU treatment, respectively. Gilts were inseminated twice at predetermined times, namely 144 and 168 h (Group 2), 128 and 144 h (Group 3), and 144 and 152 h (Group 4) after the end of RU treatment, respectively. Pregnant gilts were slaughtered at 30 d. Administration of Rc 104 h after the end of RU feeding synchronized ovulation over a 24-h time window in 97.9% and 100% of the gilts of Groups 3 and 4, respectively, whereas Rc administration at 120 h (Group 2) only successfully synchronized 88.9% of the gilts over 24 h. Ovulation rates of gilts of Groups 2 and 4 were similar to that of the control group. Pregnancy rates were numerically higher in Groups 2 and 3 (92% and 96%, respectively) compared with those of Groups 1 and 4 (84% and 81%, respectively). Combination of eCG with Rc administration at 104 h (Group 3) increased ovulation rate (+4 CL) but decreased embryo survival to 62% at Day 30. The weaned sow experiment involved 61 sows of a range of parities (2.7 ± 0.9), allocated to two control groups (Control 104 group and Control 94 group) and two treated groups (Rc104 group and Rc94 group), which received 10 μg Rc at 104 and 94 h after weaning, respectively. The females were inseminated at detected estrus. All pregnant sows farrowed. After treatment with Rc 94 h after weaning, 100% of sows ovulated over a 24-h time window versus only 68.7% of controls. Farrowing rate and litter size of the sows treated with Rc at that time were unaffected compared with that of control sows. In contrast, Rc administration at 104 h after weaning may have been too late; only 66.7% of the treated sows ovulated during a 24-h period. This proportion was numerically lower but not significantly different than that for control sows. Farrowing rate and litter size of treated sows were not significantly different than that of controls. Administration of Rc at the dose and times selected in this study tightened synchrony of ovulation in gilts and in sows after weaning. It remains to be established if such a synchrony is suitable to obtain good fertility after a single artificial insemination at a predetermined time.     

Short-term effect of rate control on plasma endothelin levels of patients with tachyarrhythmias

Radiofrequency catheter ablation or modification of the atrio-ventricular junction is an effective therapy of drug refractory supraventricular tachyarrhythmias (ST). Higher endothelin (ET) levels were observed during nonsustained STs. We aimed to examine the effect of sustained STs and the applied rate-control therapy on plasma ET levels. Twenty-two patients (12 men; mean age, 64.4 +/- 13.2 years; ejection fraction, 41.8 +/- 11.2%; New York Heart Association (NYHA) class I: 3 cases, NYHA II: 11 cases, and NYHA III: 8 cases) suffering of atrial fibrillation (n = 11), atrial flutter (n = 7), atrial paroxysmal tachycardia (n = 3), or sinus tachycardia (n = 1) were studied, having coronary artery disease (n = 8), dilative cardiomyopathy (n = 5), or no underlying diseases (n = 9). All groups went under catheter ablation (same protocol, duration: 35 +/- 10.3 mins; rate before ablation, 100-170/min in every case; after ablation, 70-80/min in Groups I and II and 70-90/min in Group III). A pacemaker (PM) was implanted 2 months before ablation in Group I (n = 9) and during ablation in Group II (n = 7). No PM was implanted in Group III (n = 6). A control group (n = 13; 7 men; mean age, 66.15 +/- 6.7 years) with sinus rhythm got a PM without ST and ablation. Blood samples were collected from the cubital vein immediately before (control), and 5 mins and 24 hrs after ablation. Plasma ET-1 and big ET-1 levels were measured after immunoprecipitation with Western blot analysis. There were no differences between plasma ET-1 levels in the ST groups and the control group (Groups I, II, and III vs. control group: 0.66 +/- 0.04 fmol/ml, 0.93 +/- 0.12 fmol/ml, and 0.68 +/- 0.05 fmol/ml vs. 0.50 +/- 0.05 fmol/ml, respectively; P < 0.05). Comparing the control, 5-min, and 24-hr samples, ET-1 levels decreased significantly after supraventricular tachycardia ablation in Groups I and III (control vs. Group I, 5 mins and 24 hrs: 0.66 +/- 0.04 fmol/ml vs. 0.50 +/- 0.04 fmol/ml and 0.29 +/- 0.05 fmol/ml; control vs. Group III, 24 hrs: 0.68 +/- 0.05 vs. 0.34 +/- 0.05 fmol/ml; P < 0.05). No plasma big ET-1 changes were measured in any of the groups. The rapid decrease of ET levels after catheter ablation suggests that a high ventricular rate can be a trigger of ET production. PM implantation procedure seems to interfere with the ET decrease in ST patients.     

Combined administration of gonadotropin-releasing hormone, progesterone, and meloxicam is an effective treatment for the repeat-breeder cow

In practice, the etiologic treatment of the repeat-breeder cow is nearly infeasible. In this study, we tested the hypothesis that a combined treatment would benefit the conception rate of repeat-breeder cows. The components of this regimen target ovulation defects, late progesterone (P4) rise, and premature luteolysis. In a 5-year period, 402 repeat-breeder cows were divided in five groups, and treatment regimens consisted of the following: gonadotropin-releasing hormone (GnRH; Group 1, n = 115, 0.012 mg buserelin im 4 to 6 h before artificial insemination); P4 (Group 2, n = 51, 100 mg P4 intravaginally, on Days 5 to 7); meloxicam (Group 3, n = 31, 0.5 mg kg⁻¹, 24 h⁻¹ melοxicam sc, on Days 16 to 18); GnRH + P4 + meloxicam (Group 4, n = 98); and no treatment (Group 5, control, n = 107). Artificial insemination was conducted only after overt estrus; thereafter, the duration of the estrous cycle was assessed in all cows that were detected to return to heat. The conception and pregnancy rate was compared among groups. The proportion of cows that returned to estrus after artificial insemination did not differ among groups; the duration of estrous cycle was the shortest in Group 1 and the longest in Group 4. In Group 4, pregnancy rate was higher (P < 0.05) than that of Groups 1 and 5 (35.71% vs. 20.00% and 17.76% for Groups 4, 1, and 5, respectively), but though numerically higher, it did not differ statistically from that of Groups 2 (27.45%) and 3 (22.58%). Our results imply that a multifaceted protocol has to be applied for the successful treatment of the repeat-breeder cow.