Past orientation of the lunar spin axis.

The orientation of the lunar spin axis is traced from the early history of the earth-moon system to the present day. Tides raised on the earth by the moon have caused an expansion of the lunar orbit. Tides raised on the moon by the earth have de-spun the moon to synchronous rotation and driven its spin axis to a Cassini state-that is, in a coprecessing configuration, coplanar with the lunar orbit normal and the normal to the Laplacian plane (which is at present coincident with the normal to the ecliptic). This combination of events has resulted in a complex history for the lunar spin axis. For much of the period during which its orbital semimajor axis expanded between 30 and 40 earth radii, the obliquity of the moon was of order 25 degrees to 50 degrees . In fact, for a brief period the obliquity periodically attained a value as high as 77 degrees ; that is, the spin axis of the moon was only 13 degrees from lying in its orbit plane.

Large-scale variations in the obliquity of Mars.

Large-scale variations in the obliquity of the planet Mars are produced by a coupling between the motion of its orbit plane due to the gravitational perturbations of the other planets and the precession of its spin axis which results from the solar torque exerted on the equatorial bulge of the planet. The obliquity oscillates on a time scale of approximately 1.2 x 10(5) years. The amplitude of this oscillation itself varies periodically on a time scale of 1.2 X 10(6) years. The present-day obliquity is approximately 25.1 degrees. The maximum possible variation is from about 14.9 to 35.5 degrees. Signtificant climatic effects must be associated with the phenomenon.

Periodic insolation variations on Mars.

Previously unrecognized insolation variations on Mars are a consequence of periodic variations in eccentricity, first established by the theory of Brouwer and Van Woerkom (1950). Such annual insolation variations, characterized by both 95,000-year and 2,000,000-year periodicities, may actually be recorded in newly discovered layered deposits in the polar regions of Mars. An additional north-south variation in seasonal insolation, but not average annual insolation, exists with 51,000-year and 2,000,000-year periodicities.

Alterations in plasma gonadotrophin patterns caused by sodium pentobarbitone in ewes at oestrus and in anoestrous ewes after infusion of oestradiol.

A radioimmunoassay system for the measurement of ovine follicle-stimulating hormone (FSH) was established. After the onset of normal oestrus, there were simultaneous surges of luteinizing hormone (LH) and FSH, and 24 h later, a surge of FSH alone. Administration of sodium pentobarbitone when the dual surge of LH and FSH was expected inhibited the release of LH, but prolonged that of FSH. Development of corpora lutea that took place immediately was normal in ewes treated with sodium pentobarbitone, but after the subsequent oestrus, the life-time of corpora lutea was abnormally short. When sodium pentobarbitone was administered at the time when the second surge of FSH was expected, no effect was observed on the level of LH or FSH. Subsequent development of corpora lutea was similar to that in the non-treated group. Administration of sodium pentobarbitone at the expected time of the dual surges of LH and FSH after infusion of oestradiol to anoestrous ewes blocked the release of both LH and FSH. Administration of sodium pentobarbitone at the expected time of the second surge of FSH after infusion of oestradiol delayed the increase in the level of FSH. In a pilot experiment after combined infusion of androstenedione and oestradiol, sodium pentobarbitone did not completely inhibit the release of FSH, but the release of LH was totally prevented.

Parturition in the goat: plasma concentrations of prostaglandin F and steroid hormones and uterine activity during late pregnancy and parturition.

Changes in plasma concentrations of hormones and uterine activity associated with spontaneous parturition in the goat were examined. No change in oestradiol-17beta concentration was detected during the experimental period, but oestradiol-17alpha consistently increased in concentration 3-4 days before parturition. This was followed by an increase in prostaglandin F two days later, while a pre-partum decline in progesterone concentration occurred 18-20 h after the significant increase in prostaglandin F. The onset of uterine contractions coincided with a significant decline in progesterone concentration and a period of continually rising prostaglandin F and oestradiol-17alpha concentrations. Uterine activity expressed in Montevideo units did not change until 10-8 h before foetal expulsion. These results support the hypothesis that in the goat the elevated prepartum concentration of prostaglandin F brings about luteolysis and a subsequent decline in progesterone concentration.

Opioid involvement in LH release during the negative feedback effects of oestradiol and progesterone in dairy cows.

To create a clearly defined and uniform feedback phase of oestradiol, 1 mg oestradiol benzoate (OE2) was injected i.m. either 15-43 days post partum in 7 cows (Expt 1), or 12 h after prostaglandin oestrus synchronization of 4 cyclic cows (Expt 2 and 3). An endogenous opioid peptide (EOP) antagonist (250 mg naloxone), an EOP agonist (300 mg morphine), or a combination of the two was given in Expt 1, 2 and 3 respectively as a single i.v. injection in cows 16-18 h after OE2, i.e. in the negative feedback phase and before the expected onset of an induced luteinizing hormone (LH) surge. Blood samples were collected every 15 min for 1 h before and 2 h after each treatment. In Expt 1, naloxone failed to increase LH release when given during the negative feedback phase, but caused excessive release in one cow in which the LH surge had just begun. In all cows in Expt 2, morphine suppressed LH release (P less than 0.05). In Expt 3, naloxone prevented the suppressive effects of morphine for the first hour after treatment; a transient rise in LH occurred in one cow in which treatment was given 1 h before the start of the LH surge. In Expt 4, 250 mg naloxone was injected i.v. into 4 cows that had a plasma progesterone concentration of 1.5-3.1 ng mL-1 in the luteal phase of the oestrous cycle: naloxone failed to increase LH concentrations. It is concluded that LH can be further suppressed by opiates given to cows during the negative feedback phase of oestradiol.(ABSTRACT TRUNCATED AT 250 WORDS)

A mixed-effects time-to-event analysis of the relationship between first-lactation lameness and subsequent lameness in dairy cows in the UK.

Data for 611 second-lactation and 251 third-lactation cows were examined using mixed-effects time-to-event models to determine the shape of the hazard, quantify relative risk and estimate herd- and sire-level variation in time to lameness. The semi-parametric Cox and fully parametric Weibull models were suggested from univariable Kaplan-Meier plots. Time to all-lameness, claw-horn lameness and skin lameness were modelled. Explanatory variables were season of current-lactation calving, age at first calving and first-lactation lameness history (whether all-lameness or claw-horn and skin lameness). In mixed-effects models of lactation-2 lameness, previously lame cows had a significantly increased hazard (hazard ratio (HR)=2.0 for all types of lameness and HR=3.2 for claw-horn lameness) compared to those not previously lame. These relationships were less marked in the third lactation. There was little evidence for an effect of age at first calving, whilst possible differences between calving seasons were observed. The hazard function suggested that the rate of lameness was roughly flat across each lactation. Herd-level variation was more evident for infectious foot diseases. The contribution of the sire increased with parity and might be important for sole ulcer and white-line disease.

Generalised additive models and hierarchical logistic regression of lameness in dairy cows.

We examined the relationship between lameness (defined by locomotion score) and four time-related variables using data collected from a study of cattle lameness conducted in the UK from 1998 to 1992. The data were 19,667 locomotion scores for 1790 cows from 27 dairy herds; the four variables were time-from-calving, time of year, parity and time spent in the study. The shape of the relationships between calving and temporal variables and lameness were assessed using loess smoothed terms in a multivariable logistic generalised additive model (GAM). Polynomial relationships derived from the GAM then were included in a Bayesian hierarchical logistic-regression model incorporating between-herd, between-cow and within-cow random effects. The final hierarchical multivariable model showed that the most important variable influencing the probability of lameness was the time of scoring in the study; but, parity, time of year and time-from-calving also were significant. Between-herd and between-cow effects were of roughly equal importance.

Opioid modulation of the hypothalamo-pituitary-adrenal axis in dairy cows.

Plasma cortisol responses to an intravenous bolus treatment with 250 mg naloxone, 300 mg morphine or a combination, were studied in Holstein-Friesian cows; 4 in early lactation (29-43 d postpartum) and 7 in mid-lactation (90-155 d post-partum). Blood samples were collected every 15 min from 60 min before to 90 min after treatment. Naloxone induced an immediate increase in cortisol concentration, reaching a peak within 30 min. The cortisol response (area under the curve) was positively correlated with pre-naloxone cortisol concentrations (r = 0.7, p < 0.05). The mean increase in cortisol concentration after naloxone appeared to be lower in early lactation (1.8 ng/ml) than in mid-lactation (8.3 ng/ml). In contrast, morphine consistently suppressed mean tonic plasma cortisol concentration by 2.7 ng/ml below baseline for at least 90 min. When given with morphine, naloxone counteracted the suppressive effects; the cortisol response was similar to that after naloxone alone. A cow in mid-lactation, suffering from chronic lameness (joint infection), gave opposite results, i.e., treatment with morphine alone increased cortisol concentration, whereas morphine with naloxone did not result in the expected large increase in plasma cortisol concentration. In conclusion, the hypothalamo-pituitary-adrenal axis of dairy cows appears to be under suppressive opioidergic control. However, the opioidergic system involved in hypothalamo-pituitary-adrenal functions of an animal under chronic stress behaved in an opposite manner.

Comparison of reproductive performance in Belgian dairy and beef cattle.

A computerized program was written to collect, evaluate and compare reproductive performance data of 2004 beef (Belgian Blue breed) and 1649 dairy (Friesian Holstein and German Red) cattle in 35 Belgian herds (6 suckler beef herds, 9 milked beef herds and 20 dairy herds). Reproduction data were collected at monthly herd health visits. No difference in age at first calving was observed. Significant differences were observed among the 3 kinds of herds, and the best results were obtained in dairy herds for the calving interval, interval from calving to the first estrus, interval from calving to the first service and average number of days open. Concerning these parameters, first calvers had lower results than multiparous cows, mainly in suckler and milked beef herds. Significant differences were noted in the number of services per pregnancy. Heifers that had never calved presented the highest fertility. Primiparous beef cows had higher fertility than pluriparous cows. In dairy herds, pluriparous cows had higher fertility than primiparous cows. Estrus detection was better in milked beef herds than in suckled beef and dairy herds. Suckled beef herds had the lowest incidence of metritis and ovarian cysts of the three types of herds. Rates of abortion, overall culling and retained fetal membranes were similar in all the herds. The percentage of animals removed for infertility was highest in milked beef herds and lowest in dairy herds. Because 90% of the 1159 calvings recorded in the beef herds required a caesarean section, the reproductive performance of beef cattle represent results after caesarean section.

Histopathological and morphometric studies on the hooves of dairy and beef cattle in relation to overgrown sole and laminitis.

In dairy cattle, histopathology of the outer hind claws with overgrown sole revealed arteriosclerosis of blood vessels at the ulcer site in the sole. The laminae did not show any hyperplasia of the epidermis and thrombi were not seen in the blood vessels. Partial or complete disappearance of onychogenic substance was observed in the sole as well as in the wall epidermis. In beef animals, typical changes suggestive of chronic laminitis were seen: these included hyperplasia of the epidermis of the laminae, thrombus formation, arteriosclerosis in the corium of the sole, the abaxial wall and the coronary corium. Morphometric analysis quantified measurements of hooves of normal, beef and dairy cattle. It may be concluded that the changes associated with overgrowth of the sole in dairy cattle are localized to the sole without involvement of the laminae and that the term laminitis is not appropriate in the condition seen in dairy cattle.

Gross and histopathological study of endotoxin-induced hoof lesions in cattle.

In young cattle infusion of Escherichia coli endotoxin resulted in sole and wall haemorrhages that were more severe in the hind than in the fore feet. Histopathological examination of biopsies taken 5 days after infusion showed separation at the tips of the laminae, changes in the vascularity of the dermal papillae and laminae, lightly stained material in the sole horn and degeneration of the epidermal cells of the laminae and papillae. Later, densely stained material in the tubules of the sole, arteriosclerosis in all parts of the corium and proliferative changes in the laminae were seen. It is concluded that endotoxin can induce diffuse aseptic pododermatitis in cattle, characterized by initial degenerative changes in the papillae and laminae followed by proliferative changes in the laminae and arteriosclerosis in all parts of the corium.

Is stress really all that important?

There is growing concern in many parts of the world that fertility of dairy cattle is reducing as milk yields increase. Stress could be one important cause. As an example, fertility is lower after caesarian operations. Delayed uterine involution after dystocia is associated with abnormal ovarian cyclicity and prolonged intervals to the next pregnancy. There is a greater reduction in fertility as the clinical conditions of lameness, milk fever or mastitis worsen. Changes in social groupings greatly increase the number of inseminations required per pregnancy. Transport reduces the number of CL after superovulation, and can interfere with pregnancy rates after estrous synchronization. Embryos collected from heat-stressed donors are less viable and have delayed trophoblast function. Human-animal interactions influence stress-responses in cattle--the behavior of stockman and embryo transfer personnel could affect success. Putting aside financial aspects, exposure of an animal to avoidable stress compromises welfare, whether application of biotechnology is involved or not. The fact that stressors can be deleterious to such an important function as reproduction, emphasizes that stress is very important and should be minimized whenever possible.

Relationship between an increase in plasma cortisol during transport-induced stress and failure of oestradiol to induce a luteinising hormone surge in dairy cows.

This study investigated whether the stress associated with a 30-minute journey in a truck could distort the oestradiol-induced surge of luteinising hormone (LH) in dairy cows. Altogether 20 journeys were monitored, 16 to 18 hours after intramuscular administration of 1 mg oestradiol benzoate (OE2). Plasma cortisol concentration was elevated (P less than 0.001) within 30 minutes of the start of each journey, even when the journey was repeated at about weekly intervals, indicating a lack of habituation. The LH surge in response to 11 OE2 treatments in nine non-cycling cows within 30 days after calving was either absent (one cow) or significantly delayed, of shorter duration or of lesser amplitude following transport, compared with untransported OE2-treated controls. However, in six cycling cows, 58 days or more after calving, transport affected the LH surge only once. Even in these cows, the LH surge did not start until the cortisol concentration returned to normal, which may suggest a transient postponement of the LH surge by transport. In conclusion, transport impaired the LH surge in early post partum cows with little or no effect after ovarian cyclicity was resumed. It is hypothesised that endocrine events leading to the onset of the LH surge are more vulnerable to stressors in early post partum cows and in the natural situation this might be responsible for the occurrence of anovulation and cystic ovarian disease.

Lack of LH response to oestradiol treatment in cows with cystic ovarian disease and effect of progesterone treatment or manual rupture.

The luteinising hormone (LH) surge in response to 1 mg oestradiol benzoate intramuscular injection was studied on 67 occasions in 45 cows with cystic ovarian disease 20 to 150 days post partum. Cows diagnosed as having luteal cysts were given 500 micrograms cloprostenol intramuscularly 24 hours before oestradiol, to induce luteolysis. Oestradiol benzoate was also given to eight post partum acyclic and eight cyclic cows and in all these cases a control LH response was characterised for comparison. Eight of 17 cows with luteal cysts (47 per cent), and 10 of 21 cows with follicular cysts (48 per cent), released LH in response to oestradiol. Some cows with cysts were given one of two treatments. Seven cows with follicular cysts were treated with a progesterone-releasing device (PRID) for seven days: all responded to a second oestradiol treatment given 24 hours after removal of the PRID. Luteal cysts in three cows and follicular cysts in nine cows were ruptured manually: only one cow (a luteal case) responded to the second oestradiol treatment given 24 hours after manual rupture. In eight cows initially diagnosed with luteal cysts, cloprostenol was not given and plasma progesterone concentration at the time of oestradiol treatment was high (over 0.9 ng ml-1): none released LH in response to oestradiol. As manual rupture did not improve the LH response to oestradiol, it is concluded that the defective LH response to oestradiol in cows with cystic ovarian disease was not influenced in the short-term by cyst fluid contents.(ABSTRACT TRUNCATED AT 250 WORDS)

A systematic compilation and classification of the literature on lameness in cattle.

This paper presents the first systematic review of the literature on lameness in cattle. It identifies, tabulates and classifies relevant published work and was conducted using electronic reference databases (BIDS ISI, BIOSIS, MEDLINE and the CAB Abstracts CD-ROM). A total of 1373 unique references were obtained from 1981 to 2000, of which 914 were written in the English language. A written search protocol was designed to ensure transparency and repeatability. Pilot studies were undertaken to create search terms that minimised bias and ensured relevance. Electronic files of the search terms allow the database to be updated in future. A further 93 references were included from the most recent international conference on lameness giving a total of 1007 English language references. The systematic review process is described, including a method of classifying papers according to their study design and statistical analysis, and it is hoped that other veterinary researchers will conduct similar reviews in their fields. The compiled and classified references are available as a searchable database through the web-sitehttp://cattle-lameness.dhs.org/. The review may be used in several ways; to identify practical interventions to reduce lameness in dairy cows and to use the resultant web-site as the basis of a decision support system for farmers, veterinarians and advisors.

Experiences of University of Liverpool veterinary students during the 2001 epidemic of foot-and-mouth disease.

The 2001 epidemic of foot-and-mouth disease disrupted the teaching of practical farm animal work for much of that year. Many students in their clinical years in the Faculty of Veterinary Science at the University of Liverpool, went to help to control the disease, both in place of some normal term-time activities and as part of their extramural studies out of term time. This paper, which is based on a questionnaire survey of the students, describes their experiences, the types of work they did, the skills they acquired and their views on the effects of the epidemic on their studies. The vast majority of students felt they had benefited from their experiences and had contributed to combating the epidemic.

Welfare implications of modern artificial breeding techniques for dairy cattle and sheep.

The legislation which protects animals from cruelty and poor welfare is described, from both a European and British perspective. Using well-established definitions of welfare, it can be seen that certain current practices related to farm animal breeding may constitute poor welfare particularly for dairy cattle. Taking only scientific measures of welfare as criteria for acceptable practice may not completely satisfy public concern over some biotechnical innovations in animal breeding. A reassessment of attitudes towards manipulation of animals for human use may be necessary.

Development of a microcomputer system for recording veterinary visits, preparing accounts, and as an aid to herd fertility and herd health schemes.

A computerised method of recording clinical information from farm animal practice visits and using it for herd fertility visits, herd health schemes, the investigation of disease outbreaks and as a source of data for epidemiological studies was developed in the University of Liverpool farm animal practice. The system stores clinical and reproductive information in a data base from which data can be readily extracted and analysed, and monthly bills produced.