Untreated Lambs Research Articles

CYTOCHROMES IN BRAIN MITOCHONDRIA FROM LAMBS WITH ENZOOTIC ATAXIA

AbstractMitochondria from the cerebral cortex of untreated lambs from areas in which enzootic ataxia occurred showed a lower content of haem a (from cytochromes a and a 3) than mitochondria from control lambs with adequate copper but the haems of cytochromcs b2 c1 and c were not depleted. Cytochrome oxidase activity was closely correlated with the content of haem a (P<0.001) but there was no correlation with total mitochondrial copper which was always present in molar exccss of haem a. It is concluded that the lowered cytochrome oxidase activity in mitochondria from untreated lambs is immediately attributable to depletion of haem a. In clinically ataxic lambs that showed degradation of myelin in thc spinal cord, brain cytochrome oxidase was depressed by no more t han 60%. Arguments are advanced that this depletion was not sufficiently severe to have led to respiratory constraint

Selenium-responsive unthriftiness of young merino sheep in Central Victoria.

A trial was carried out to determine whether selenium responsive unthriftiness existed on a property in the Strathbogie ranges of Central Victoria where unthriftiness of young sheep has been a problem for 10 to 20 years. White muscle disease had been diagnosed on the property in the previous year and on other properties in the area. Eighty Merino ewes and lambs were allotted to one of 4 groups in a 2 x 2 factorial designed trial in which sodium selenite (0.1 mg/kg) was given orally to ewes and/or lambs at marking time and to treated lambs at 3 monthly intervals thereafter. Selenium treatment of the ewes had no significant effect on subsequent lamb performance. Selenium treatment of the lambs produced significant responses: mortality in treated groups was 0% compared with 17.5% in untreated groups; body weight gains were 1.9 kg higher at both weaning and one year of age in treated than in untreated lambs; mean fleece weight was 14.4% higher in treated lambs and they produced 39% more wool than the surviving untreated lambs.

The effect of natural worm loss on the estimate of anthelmintic activity in an anthelmintic test with Haemonchus contortus.

An anthelmintic test was carried out in lambs against fourth-stage larvae of Haemonchus contortus to determine whether a natural loss of worms from either untreated control animals or from animals treated with anthelmintic affected the estimated activity of the anthelmintic.Thirty-two lambs were each infected with 1500 larvae of H. contortus on 4 consecutive days and divided into 4 groups of 8 animals. Two groups of lambs were treated with anthelmintic on day 7, the first group being slaughtered on day 9 and the second on day 29. An untreated control group was slaughtered 7 days after infection and a second control group was killed 29 days after infection.The numbers of worms recovered indicated that in the untreated control lambs there was an estimated daily loss of about 7% of the parasite population between the first day of infection and day 29, and in the lambs given anthelmintic an estimated daily loss of about 2% of the worm population was indicated between days 9 and 29. If the rate of worm loss is not the same in the untreated control hosts and in the treated animals, the estimate of anthelmintic efficacy will vary according to the time of autopsy. To minimize the possibility of an incorrect result occurring in an anthelmintic trial due to a natural loss of worms, it is recommended that the untreated control and the treated lambs are slaughtered on the same day, and that the autopsy is carried out as soon as possible after anthelmintic therapy.

CONTROL OF NUTRITIONAL MUSCULAR DYSTROPHY IN LAMBS BY VITAMIN E IMPLANTATIONS

An implantation technique utilizing slow-release vitamin E pellets was evaluated as a means of controlling nutritional muscular dystrophy (NMD). Seventy-eight pregnant ewes were fed a dystrophy-producing hay, and implantations were made on 36 ewes at mid-pregnancy with four pellets, each containing 665 mg D-α-tocopherol; the remainder (42 ewes) were kept as control. Twenty-seven lambs from the control ewes and 21 from the implanted ewes were also implanted with two pellets, each containing 665 mg D-α-tocopherol. Several muscles were examined for NMD lesions. Implantation of D-α-tocopherol to the Iambs prevented almost completely the occurrence of NMD. Plasma vitamin E levels in both groups of implanted lambs were significantly higher than in untreated lambs from the untreated ewes during the 4-month period of biweekly blood sampling. Large variability was encountered in the plasma vitamin E levels of implanted lambs. Implantation of the ewes provided only partial protection to the offspring but implantation of lambs was almost completely effective against NMD.

Metabolism of vitamin E in sheep.

1. The metabolism of tritium-labelled tocopherol was investigated in thirty-six wethers and forty-two ewes fed on hay known to produce nutritional muscular dystrophy (NMD).2. In one experiment, the effect of selenium or vitamin E or both on the metabolism of tritium-labelled tocopherol was studied. No difference was found in the incorporation rate of radioactivity in tissues due to the addition of either of these components.3. In a second experiment, significantly more radioactivity was found in the tissues of sheep dosed intramuscularly than of those dosed by stomach tube into the rumen. Excretion of radioactivity was rapid when labelled tocopherol was given into the rumen.4. In a third experiment, the efficiency of vitamin E in preventing NMD in lambs was tested. Supplementation with vitamin E of the diet consisting of NMD-producing hay and given to ewes was ineffective as a prophylactic treatment. Direct administration of vitamin E to the lambs completely prevented the occurrence of NMD. Plasma vitamin E concentrations in the treated lambs were significantly higher than in untreated lambs at weekly sampling over a 4-month period regardless of whether the lambs were born from ewes treated with the vitamin or not.

The effect of diethylstilbestrol on nitrogen excretion in sheep.

Administration of 2 mg of diethylstilbestrol (DES) daily to lambs reduced total urinary nitrogen excretion, urea excretion, plasma urea concentrations, and liver arginase activity. The percent of filtered urea reabsorbed was greater in untreated lambs, thus suggesting that the increased nitrogen conservation observed following DES administration to ruminants is not the result of a direct effect of DES on tubular reabsorption of urea but on nitrogen metabolism.

The Effect of Corticosteroid on the Pathogenicity and Development of Fasciola Hepatica in Lambs

The development and pathogenicity of Fasciola hepatica was compared in corticosteroid-treated and untreated groups of lambs. Accelerated growth of the flukes in the treated lambs was associated with extensive hepatic haemorrhage and marked clinical signs. Splenomegaly and hepatic fibrosis in the untreated lambs was absent from the treated group. Comparaison du développement et du caractère pathogène de la Fasciola hepatica entre un groupe d’agneaux traités au corticostéroide et un groupe non traité. La croissance plus rapide des douves chez les agneaux traités a été associée à d’abondantes hémorragies hépatiques et des symptomes cliniques marqués. La splénomégalie et la dégénérescence fibreuse du foie qui se sont vérifiées chez les agneaux non traités ne se sont pas produites dans le groupe n’ayant pas reçu le traitement. Die pathogene Virulenz und die Entwicklung von Fasciola hepatica bei Lämmern, die mit Korticosteroiden behandelt worden waren, und bei einer unbehandelten Kontrollgruppe wurden verglichen. Die in der behandelten Gruppe auftretenden Leberhämatome und ausgeprägten klinischen Krankheitszeichen wurden mit dem beschleunigten Wachstum der Leberegel in Verbindung gebracht. Die bei unbehandelten Lämmern beobachtete Milzvergrösserung und Leberfibrose trat bei behandelten Lämmern nicht auf. Se comparó el desarrollo y la patogenicidad de la Fasciola hepática en grupos de corderos tratados con corticosteroide y grupos no tratados. El desarrollo acelerado de los trematodos en los corderos tratados iba acompañado de extensa hemorragia hepática y marcados indicios clínicos. La esplenomegalia y la fibrosis hepática de los corderos no tratados estaba ausente en el grupo tratado.

Vitamin B12, in the blood of grazing cobalt-deficient sheep

Abstract Ewes grazing cobalt-deficient pastures were given cobaltic oxide pellets (cobalt “bullets”) 23 weeks before lambing commenced. At intervals, blood samples, for vitamin B12 assay, were taken from groups of untreated and treated ewes, and later, from groups or subgroups of untreated lambs from treated or untreated ewes, and from sub-groups of lambs given cobalt bullets directly. Also, livers and kidneys of lambs that died at or near to birth were assayed for vitamin B12. Cobalt treatment of ewes resulted in markedly increased vitamin B12 concentrations in the livers and kidneys of newborn lambs. However, although cobalt treatment of the ewes ameliorated, or delayed, the onset of cobalt deficiency disease in their lambs, the disease among the latter developed five weeks before weaning, that is, by the time the lambs were three to four months old. Treatment with cobalt bullets greatly increased vitamin B12 concentrations in the sera of ewes and lambs. At what appeared to be incipient stages of cobalt...

No effect of copper dosing on the growth and vitamin B12 status of grazing cobalt-deficient and cobalt-dosed lambs.

Abstract Extract Although copper deficiency disease causing ataxia in lambs has been of common occurrence in this and other countries, there is not, to the writers' knowledge, any incontrovertible published evidence that copper supplements will improve the growth rates of copper-deficient sheep. However, some New Zealand experience has suggested that copper might have a beneficial effect on the growth of lambs that are cobalt-deficient. Thus, on a farm near Apiti (Pohangina County), G. F. Sommerville (pers. comm.) obtained a marked statistically-significant liveweight response to cobalt “bullets”, and a small though non-significant difference in favour of copper-injected as compared with untreated lambs. Analysis of pasture and liver samples from two small areas were suggestive of a dual deficiency of copper and cobalt at Pakipaki, Hawke's Bay, in the North Island (Cunningham and Laing, 1957), and at Waikari, North Canterbury, in the South Island (I. J. Cunningham, pers. comm.). Ataxia in lambs was not a ...

A comparison of vitamin B12concentrations in livers and kidneys from cobalt-treated and mildly cobalt-deficient lambs

Abstract Vitamin B12 concentrations were determined in the livers and kidneys of (1) lambs treated with cobaltic oxide pellets and (2) untreated lambs grazing cobalt-deficient pastures. Vitamin B12 concentrations in livers and in kidnevs of cobalt-treated lambs ranged from 0.44 to 1.6 µg;/g (mean 0.84 µg/g) and from 0.25 to 0.75 µg/g (mean 0.52 µg/g) respectively. In livers and kidneys of presumed mildly cobalt-deficient lambs concentrations ranzed from 0.09 to 0.16 µg/g (mean 0.12 µg/g) and from 0.19 to 0.26 µg/g (mean 0.23 µg/g) respectively. For cobalt-sufficient lambs liver/kidney vitamin B12 ratios were all greater than one. For cobalt-deficient lambs ratios were all less than one. Factors that may limit the diagnostic value of vitamin B12 concentrations, particularly in kidney, are discussed.

Further studies of hexoestrol implantation of Blackface wether lambs

1. In the summer of 1958, 15 mg. of hexoestrol was administered to Blackface wether lambs in one of the following ways; 5 mg. before weaning followed by two 5 mg. tablets at weaning, three 5 mg. tablets at weaning, and thirdly a single 15 mg. tablet at weaning. In a further series of experiments in 1959 the effect of both raising the pre-weaning implantation to 10 mg., and the total hexoestrol dosage to 20 mg. was studied.2. Suckled lambs implanted with 5 mg. of hexoestrol at the milk clip gained significantly more in live-weight (18%) up to weaning in 1958 than did untreated lambs; in 1959 the difference was only 11%.3. Between weaning and the end of the trial all treatments with the exception of that in which hexoestrol dosage was raised to 20 mg. showed a very highly significant increase in live-weight gain over untreated lambs, the increases ranging from 26 % to 54%.4. In neither year was the overall gain in live-weight from pre-weaning to the end of the trial significantly increased by implanting part of the hexoestrol dose prior to weaning.5. Live-weight gain of the lambs was not significantly increased when three 5 mg. tablets of hexoestrol replaced a single 15 mg. tablet.6. The implanting of lambs with 20 mg. hexoestrol failed to give a response superior to that obtained with 15 mg. hexoestrol.7. Each group of lambs receiving hexoestrol treatment showed an increased average carcass weight.

Hexoestrol implantation of Blackface wether lambs

1. Sixty-four Blackface wether lambs, weaned some 8 days previously from the hill were divided into two similar groups. One group of lambs was implanted with 15 mg. hexoestrol.2. The treated lambs had gained an average of 2·32 lb., and 3·88 lb. live-weight more than the control group, after 4 and 7 weeks respectively.3. The mean carcass weight of 23 hexoestrol-implanted lambs was 1·5 lb. greater than that of the same number of untreated lambs.4. Carcass grading provided no evidence of a deterioration in quality as the result of hexoestrol implantation.5. Light lambs responded at least as well as heavy lambs to the hormone.

The effects of inbreeding on four families of Peppin Merinos. III. The influence of crude pituitary extract on inbred lambs

Treatment of inbred lambs with crude pituitary extract produced a highly significant increase in griwth rate over the first 10 weeks when compared with untreated inbred lambs. Continued treatment from 10 to 23 weeks of age did not cause any further change in growth rate. Differences between treated and untreated lambs in body weight and size were maintained long after cessation of treatment. Wool production was significantly increased during, but not after, the treatment period. At 12 months of age (7 months' fleece), treated and untreated groups did not differ significantly in wool production, mean fibre weight, mean fibre length, or total fibre number. The ratio of secondary to primary follicles did not differ significantly at any stage. Similar treatment produced no detectable response in non-inbred lambs. It is suggested that the effect of inbreeding is partially derived from a reduction in pituitary activity. Treatment of inbred lambs caused a decrease in the variances of body weight and size and an increase in the variance of wool production. This may be explained by differences between different tissues in their hormone requirements for maximum response, and would suggest that the effects of inbreeding on the variance of any character depend on the physiological paths through which the effect is produced.

The actions and interactions of a number of factors on the response of the growing lamb to oestrogen implants

A multifactorial experiment using 576 lambs is described, designed to determine the potential value of oestrogen implants in the Australian fat lamb industry. Actions and interactions of age at implantation (5 or 9 weeks), type of oestrogen (hexoestrol or stilboestrol), dose (15 or 30mg), crossbreed (Border Leicester x Merino or Dorset Horn x Corriedale), sex (ewe or wether), and type of birth (single or twin) were examined. Owing to drought conditions nutrition was only moderate. Sixty-three lambs were lost. Mortality tended to be concentrated on 30mg-oestrogen, Dorset Horn x Corriedale, male lambs (P < 0.05). Oestrogen-treated lambs (15 and 30 mg) reached 75 lb liveweight 2.5 and 1.9 weeks earlier than untreated lambs (P < 0.001). Wether lambs grew faster than females (P < 0.01). Treatment reduced dressing percentage and carcass weight by 1.8 per cent. and 1.1 lb respectively (P < 0-001). The dose of oestrogen was unimportant but the deleterious effect of stilboestrol was greater than that of hexoestrol. Treated carcasses were downgraded (P < 0.001) and there was a highly significant interaction between sex and treatment (P < 0.001). Carcasses of ewe lambs were more seriously affected than those of wethers. Treated carcasses were longer in the leg (P < 0.05) and thinner in the loin and flank than untreated carcasses (P < 0-001). The general effect was seriously to delay maturity and market quality, with a reduction in weight of carcasses despite increased liveweight gains. It is concluded that oestrogen implantation is unlikely to have wide commercial application in fat lamb production in Australia.

The Effect of Stilbestrol upon Lamb Performance in the Feedlot

Subcutaneous implantation of a 15 mg. pellet of stilbestrol at the beginning of the feeding period increased significantly the rate of gain in lambs being fattened on various Kansas rations. Lambs given a second implant after 70 days of feeding did not gain any faster than those given only one implant. Carcass grades and dressing percentages were slightly lower in the treated lambs than in the untreated ones. Twelve lambs were lost (of 517 in the experimental tests at Garden City) from prolapse of the rectum and from excessive swelling and inflammation in the rectal or perineal region, or showing symptoms similar to those produced by urinary calculi. All 12 lambs dying from these causes had each received two implants of 15 mg. of stilbestrol. Virtually all the treated lambs, both those receiving one pellet and those receiving two, had preputial swelling and indicated distress during urination. Many of the treated lambs showed visible swelling in the perineal region. Measurements taken of the uro-genital systems of treated and untreated lambs revealed enlarged seminal vesicles, bladder, ampullae, urethra, prostate gland, and bulbo-urethral glands in the treated lambs. The most noticeable changes were seen in the Cowper's glands where in severe cases, a cul-de-sac filled with urine was developed. A possible explanation of the symptoms of urinary calculi and rectal prolapse in the treated lamb is offered.