Neuroendocrine regulation of growth hormone secretion in sheep. IV. Central and peripheral cholecystokinin

The result of alterations in the levels of CCK, in the blood and in the cerebrospinal fluid, on the functioning of the growth hormone axis has been examined in sheep. Male Coopworth sheep of about 40 kg liveweight were given various doses of CCK either intracerebroventricularly (icv) or intravenously (iv). Other similar sheep were given various doses of a CCK antagonist (loxiglumide) by the same routes. Bolus iv administration of either 35 μg or 200 μg of CCK had no effect on plasma GH levels. When given icv, however, CCK resulted in a marked (P<0.01) prolonged depression in plasma GH levels. The decrease in GH secretion could be partially attenuated by concurrent administration of loxiglumide, but was completely unaffected by concurrent administration of anti-somatostatin serum icv. Loxiglumide alone had no effect on plasma GH levels when given at up to 200 μg icv, but intravenous administration of 8 mg of the CCK antagonist resulted in an increase in plasma GH concentrations (P<0.05). Plasma levels of somatostatin, glucose and cortisol were unaffected by both icv and iv administration of CCK. These results show that CCK can have a strong GH-inhibiting effect in the brain. Furthermore, this effect seems to be independent of hypothalamic somatostatin, suggesting another GH-inhibiting system exists.     

Serum liver enzyme and histopathologic changes in calves with chronic and chronic-delayed Senecio jacobaea toxicosis.

Progressive changes in serum enzyme activity and liver histologic features were monitored in calves fed tansy ragwort (Senecio jacobaea)-contaminated pellets. The experiments were designed to simulate natural intoxicant ingestion conditions in relationship to the dose and duration of exposure to the toxic plant to correlate early laboratory diagnostic changes with the natural progression of the disease, thereby facilitating early diagnosis and intervention by veterinary clinicians. Eight calves were fed tansy ragwort and 4 additional calves served as controls. In group 1, 4 calves were continuously fed dried tansy ragwort mixed in a pelleted feed at a 5% concentration by dry weight until terminal liver disease developed. Serum liver enzyme (alkaline phosphatase, glutamate dehydrogenase, and gamma-glutamyltransferase) activities were monitored at weekly intervals in these calves and in the 2 controls. In group 2, 4 calves were fed the same contaminated feed for only 60 days, with return to normal feed for the duration of the trial. Two additional calves served as controls. Their liver enzyme activities were monitored every other week in conjunction with percutaneous liver biopsies. All 8 calves fed tansy ragwort-contaminated pellets developed terminal hepatopathy in either a chronic pattern (n = 6) or a chronic-delayed pattern (n = 2), with the onset of a moribund state or sudden death at 11 to 17 weeks and 27 to 51 weeks, respectively. The calves were euthanatized when classic terminal signs of hepatic encephalopathy first became evident. The clinicopathologic patterns of chronic and chronic-delayed toxicoses were typical of over 5,000 cases of field tansy toxicosis diagnosed at the diagnostic laboratory. Serum glutamate dehydrogenase was the first enzyme to increase in most animals, with a short-term increase to peak values followed by a rapid return to normal. This enzyme change was followed by increases in alkaline phosphatase and gamma-glutamyltransferase. Serum enzyme changes preceded development of recognizable histologic lesions. Vacuolar changes in hepatocyte nuclei, biliary hyperplasia, and fibrosis sequentially developed in liver biopsy specimens from each animal, whereas megalocytosis was not a predominant feature until necropsy. On the basis of our findings, we suggest that the optimal tests for diagnosis of pyrrolizidine alkaloid intoxication should consist of liver biopsy and determination of concurrent serum liver-enzyme activities.     

Polymorphism of the CD4 and CD5 differentiation antigens in cattle.

Monoclonal antibodies (mAbs) specific for bovine CD4 and CD5 antigens have been found to identify polymorphic determinants on these molecules. In the case of CD5, mAb IL-A67 recognises one allotypic form of the antigen while four other CD5-specific mAbs in the workshop (CC17, CC29, BLT-1 and 8C11) recognise a second allotype. The CD4-specific mAbs submitted to the workshop reacted with the cells of all animals tested. However, a further two mAbs (CC26 and IL-A18) specific for CD4 were found to react with cells only from about 85% of animals tested. Sequential immuno-precipitation experiments together with family studies showed that the allotypes of CD4 and CD5 are both inherited in a simple Mendelian manner and are co-dominantly expressed. One of the CD5 allotypes was not detected in Bos taurus animals while the gene frequency of the second allotype was only about 10% in the B. indicus animals tested. The gene frequency of the CD4 allotype detected by CC26 and IL-A18 was similar in the two sub-species.     

Genetic and physiological aspects of growth, body composition and feed efficiency in mice: a review

A review is presented of the genetic and physiological aspects of growth, body composition and feed efficiency in mice. The genetic parameters considered are: nature and extent of within and between-line genetic variation for body weight and growth rate; direct and correlated responses to selection for body weight, weight gain, feed intake and feed efficiency; direct genetic effects of the offspring (gO); maternal genetic effects (gM); heterosis in the offspring (hO); maternal heterosis (hM), and recombination effects in the offspring (rO). The physiological parameters considered are energy requirements for maintenance and growth. The role of thermoregulatory thermogenesis in relation to the partitioning of metabolizable energy between maintenance and growth requirements of large and small mice is emphasized. The relationship of feed efficiency with other traits is reviewed at length.     

Zearalenone intoxication of pigs

Mycotoxicosis due to ingestion of zearalenone was detected on 2 pig farms on the Atherton Tableland in northern Queensland. In one herd of 200 pigs, this resulted from feeding maize which had been stored with a high moisture content. In the other herd of 1400 pigs, it resulted from feeding sorghum grain which was rain affected before harvest. Concentrations of zearalenone in the feeds ranged up to 8 mg/kg. Most prepubertal gilts in the herds displayed enlarged teats and signs of oestrus such as having red, swollen vulvas. In several cases both rectal and vaginal prolapses occurred. On one of the farms, 25 pigs died as a direct result of prolapses. Autopsy of a 3-month-old gilt revealed apparently enlarged ovaries and uterine horns. Sows and boars seemed to be unaffected. Four gilts failed to conceive following mating during the period of zearalenone ingestion, but apart from this and the deaths from prolapses, production of the herds appeared to be unaffected.     

Pitfalls in immunofluorescence testing in dermatology. III. Pemphigus-like antibodies in the horse and direct immunofluorescence testing in equine dermatophilosis

Indirect immunofluorescence testing for pemphigus-like antibodies was performed on 79 horses: 28 horses with various nonpemphigus dermatologic diseases, 21 horses with various nondermatologic diseases, and 30 normal horses. Pemphigus-like antibodies were detected in 6 horses: 3 normal horses with titers of 1:40, 2 horses with dermatophilosis at titers of 1:10 and 1:80, and 1 horse with lymphosarcoma at a titer of 1:320. It was concluded that equine pemphigus-like antibodies are a potential source of misinterpretation and misdiagnosis in indirect immunofluorescence testing. Direct immunofluorescence testing for whole immunoglobulin, IgG, IgM, and IgA was performed on skin lesions from 2 horses with dermatophilosis. Diffuse intercellular deposition of whole immunoglobulin and IgG was found in both horses. It was concluded that equine dermatophilosis is a potential source of misinterpretation and misdiagnosis in direct immunofluorescence testing.     

Prevalence of gastrointestinal parasitism in Oklahoma swine

The prevalence of swine gastrointestinal parasites was determined from all listed large swine operations (28) and a geographically representative sample (70) of the population of small hog farm operations in Oklahoma. Fecal samples (n = 975) were collected from 98 farms. From the 98 farms, parasites were recovered in pig feces as follows: Ascaris, 53.0%, strongyles, 53.1%, Trichuris, 35.7%, spirurids, 6.1%, Strongyloides, 19.4%, coccidia, 57.1%, and Balantidium, 55.1%. A higher percentage (16.5%) of hogs maintained on cement floors were positive for Ascaris than were those on either dirt lots (11.9%) or slatted floors (9.9%), but pigs on dirt lots were more often positive with a higher percentage of coccidia (21.0%) than those on either cement or slatted floors (8.5% and 6.0%, respectively). Prevalence of Trichuris was essentially the same (6.8% to 11.3%) in hogs from all 3 management practices.     

Antagonism of xylazine sedation in steers by doxapram and 4-aminopyridine

Five groups of 6 fasted crossbred steers were injected IM with standard dosages of xylazine hydrochloride (0.3 to 0.5 mg/kg). At maximal sedation, the steers were injected IV with the antagonists' doxapram (1.0 mg/kg), doxapram + yohimbine (0.125 mg of yohimbine/kg), doxapram + 4-aminopyridine (4-AP; 0.3 mg of 4-AP/kg), or 4-AP + yohimbine. One group was given 1.0 ml of saline solution IV instead of antagonists. Doxapram, doxapram + yohimbine, doxapram + 4-AP, and 4-AP + yohimbine decreased mean standing time (time from antagonist injection until animal could stand unaided) to 17.0, 4.3, 3.3, and 4.5 minutes, respectively--significantly (P less than 0.05) down from a control value of 49.8 minutes. Mean total recovery time (time from xylazine injection until animal resumed eating) was decreased to 78 minutes by doxapram and 81.6 minutes by doxapram + 4-AP--significantly (P less than 0.05) down from the control value of 142.9 minutes. Respiratory character was improved (depth of respiration was increased) only by doxapram + 4-AP. Relapses to recumbency and marked sedation were not seen in steers given doxapram + 4-AP or the saline solution. One steer given doxapram, 2 given doxapram + yohimbine, and 1 given 4-AP + yohimbine relapsed to recumbency and sedation. Recovery was relatively smooth in steers given doxapram + 4-AP or 4-AP + yohimbine. Animals given doxapram or doxapram + yohimbine had difficult recoveries.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects on the oestrous cycle of dairy cows of the administration of colostrum in the mid-luteal phase

A group of 13 cows were dosed orally nine or 10 days after a normal oestrous cycle; six animals received colostrum, five animals received milk containing varying amounts of oestrone sulphate, and two cows were given milk containing a low level of oestrone sulphate. Measurements of milk progesterone levels after dosing showed that colostrum had an apparent luteolytic effect, milk containing oestrone sulphate at a level of 2000 pg/ml had a less marked effect on milk progesterone and those animals receiving milk showed no reduction in milk progesterone. These results show that there is a physiological basis for the practice of inducing overt oestrus in cows showing no visible oestrus, by dosing them with colostrum.