Adult Beef Research Articles

Tuberculosis in adult beef cattle of Mexican origin shipped direct-to-slaughter into Texas

Objective To evaluate differences in prevalence of tuberculosis (TB) in adult beef cattle that originated from different states in Mexico and were shipped direct-to-slaughter into Texas in 1995. Design Epidemiologic survey. Animals Approximately 65,000 adult beef cattle. Procedures Postmortem examinations of carcasses for detection of Mycobacterium bovis infection were conducted at slaughter plants in Texas. Specimens were collected from cattle with granulomatous lesions, stored in neutral-buffered 10% formalin or saturated sodium borate solution, and processed for histologic and bacteriologic diagnosis. Prevalence and 95% confidence intervals were estimated by state of origin. Difference between prevalences for different states was tested for significance (P< 0.05), using the proportion test. Results Overall prevalence of TB at slaughter in adult beef cattle that originated from Mexico was approximately 0.5/1,000 (34/65,233). Prevalence of TB in cattle that originated from Chihuahua (0.07) was significantly lower than that in cattle from Coahuila (0.80), Nuevo Leon (1.27), and Tamaulipas (1.81). Clinical Implications Prevalence of M bovis infection in adult beef cattle may be significantly different between states in the northern border region of Mexico. On the basis of disease prevalence and numbers of exported cattle and provided safeguards such as TB testing are continued, cattle from Chihuahua may pose a lower risk of TB transmission to Texas cattle than do cattle from Coahuila, Nuevo Leon, and Tamaulipas. To allow interstate/international movement of cattle from northern border states of Mexico, TB testing requirements should be continued. In the context of international trade, southern border states of the United States should continue collaborating with northern border states of Mexico to control and eradicate this disease. (J Am Vet Med Assoc 1998; 212:557-559)

アスコルビン酸-2-リン酸はウシ腎臓脂肪組織から調製した間質血管系細胞群の脂肪細胞への分化を促進する

Stromal vascular cells isolated from perirenal adipose tissue of adult beef cattle were cultured, and the actions of L-ascorbic acid-2-phosphate (Asc-P) on the adipocyte differentiation of these cells were investigated. The addition of Asc-P into culture medium increased adipogenic marker enzyme (glycerol-3-phosphate dehydrogenase) activity of the cells as well as the number of lipid-laden cells countable under microscopic observation, at concentrations of 50 and 500μM. Cytosolic protein content was unaffected by the Asc-P treatments. In conclusion, Asc -P enhances adipocyte differentiation of bovine preadipocytes in vitro. The results raise the possibility that adipose tissue growth in beef or dairy cattle could be manipulated by controlling blood levels of vitamin C.

Isoform-independent heart rate-related variation in cardiac myofibrillar Ca(2+)-activated Mg(2+)-ATPase activity.

In the present study, we compared the activities of the cardiac myofibrillar Ca(2+)-activated Mg(2+)-ATPase and the content of cardiac muscle mitochondrial ATPase inhibitor protein (IF1) of several mammalian species covering broad ranges of body mass and heart rate, i.e., from beef cattle to mouse. The cardiac myofibrillar ATPase from each species was assayed over a range of pCa values at pH 7.4. While the cardiac myofibrillar ATPase from all species examined showed essentially identical Ca2+ concentration dependencies with the ATPase in each species activating steeply between pCa 6.5 and 5.5, the maximal ATPase specific activity reached varied considerably from species to species, and this variation was largely independent of the predominant cardiac myosin ATPase isoform present. Thus, while adult beef cattle, pig, dog, and rabbit all contain predominantly the slow cardiac myosin ATPase isoform the cardiac myofibrillar ATPase specific activities of these four species varied over approximately a fourfold range. Moreover, there was a fairly smooth curvilinear relationship between maximum Ca(2+)-activated myofibrillar ATPase activity and median conscious heart rate for the slow cardiac myosin ATPase-possessing species examined. This smooth continuum also extended to include two species possessing the fast cardiac myosin ATPase isoform, rat and mouse. This relationship between myofibrillar ATPase activity and heart rate that appears to be applicable to a broad range of species suggests that the myofibrillar ATPase is specifically modeled or fine-tuned to the kinetic (heart rate) demand of each species and, within slow and fast heart rate ranges, is essentially independent of myosin ATPase isoform per se. Only hearts containing predominantly the slow myosin ATPase isoform contained functional levels of IF1. Finally, while it has been reported that the ratio of myosin Ca(2+)-ATPase to actomyosin Mg(2+)-ATPase activity is a good index of the percent of the fast myosin ATPase in rabbit myofibrillar preparations, we found that this relationship may be applicable to only some species.

Use of enzyme-linked immunoassays for antibody to types C and D botulinum toxins for investigations of botulism in cattle.

The development of specific enzyme-linked immunosorbent assays (ELISA) for antibody to types C and D Clostridium botulinum toxins for investigation of botulism in cattle is described. Partially purified type C and D toxins were used as antigens to develop these ELISAs. Specificity of the ELISAs was evaluated on sera from 333 adult beef and dairy cattle from areas with no history or evidence of botulism in animals or water birds. The test was also evaluated on sera from 41 herds that included herds vaccinated against botulism, confirmed botulism cases and herds from areas where the disease is considered endemic. The ELISAs detected the presence of antibody to botulinum toxins in samples from vaccinated cattle and both convalescent and clinically normal animals from unvaccinated herds with outbreaks of botulism. Antibody was also found in unvaccinated animals from herds in which there had been no diagnosed botulism cases in areas where botulism was considered endemic. Sera from some unvaccinated cattle with high ELISA reactivity was shown to be protective for mice in botulinum toxin neutralisation tests. The use of these tests in investigations of botulism in cattle is discussed.

Effect of breed, intake, and carcass composition on the status of several macro and trace minerals of adult beef cattle.

The objective was to determine the association between breed, intake, and carcass composition and the status of liver Cu, Zn, and Fe, and serum Cu, Zn, Ca, and Mg of 118 mature cows representing nine breeds of cattle. Breeds used were Angus, Braunvieh, Charolais, Gelbvieh, Hereford, Limousin, Red Poll, Pinzgauer, and Simmental. The cows were fed one of four levels of DMI: 58, 76, 93, and 111 g of DMI.wt-75.d-1. A ground alfalfa, corn, and corn silage diet was fed for up to 5 yr. There was no relationship between liver and serum concentrations of Cu, a negative correlation (P < .05) existed between liver and serum concentrations of Zn and a positive correlation (P < .01) existed between liver concentrations of Cu and Zn. Concentrations of serum Ca were positively correlated (Cu and Zn, P < .01; Mg, P < .05) with serum concentrations of Cu, Zn, and Mg, but negatively correlated (P < .01) with liver Fe. Liver Cu was higher (P < .05) for the Limousin breed than all others, except Angus. Liver Zn concentrations were higher (P < .05) for Limousin than for Pinzgauer, but no other breed differences were observed. Liver Cu concentration was not affected by daily intake, but liver Zn concentration increased (P < .05) with increased daily intake. Liver Fe concentration decreased (P < .01) in a curvilinear manner with increased daily intake. No breed differences in serum concentrations of Cu or Zn were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

An epidemiological study of Cryptosporidium parvum in two herds of adult beef cattle

Prevalences of Cryptosporidium parvum oocysts in faeces and of isotype-specific anti- C. parvum antibodies in serum of apparently healthy adult cattle on two farms were determined. On Farm 1 cryptosporidial diarrhoea had been recorded in more than 80% of calves born over the previous 5 years, whereas on Farm 2 cryptosporidiosis had never been reported. No differences were demonstrated in oocyst excretion or presence of antibodies between the two farms. C. parvum oocysts were detected in 62.4% of faecal smears collected from a total of 553 apparently healthy adult cattle. Sucrose flotation was performed on a proportion of the faecal samples. This proved a more sensitive technique, detecting oocysts in 92% of the samples tested, and highlighting the insensitivity of direct smears for detecting oocysts. More than 90% of the cattle had specific anti- C. parvum IgG, IgG 1, IgG 2 and IgM antibodies and 58% specific anti- C. parvum IgA antibodies. Results suggest that asymptomatic adults may play an important role in the epidemiology of cryptosporidiosis in calves.

Neonatal exposure to progesterone and estradiol alters uterine morphology and luminal protein content in adult beef heifers

Exposure of the developing urogenital tract to steroids can affect structure and function of adult tissues and compromise reproductive performance. This study was conducted to determine 1) if exposure of neonatal heifer calves to progesterone (P) and estradiol benzoate (E), delivered from a commercial growth-promoting implant, would affect adult uterine morphology or uterine luminal protein content; and 2) whether such effects would be related to neonatal age at the first exposure. At birth (Day 0), 20 crossbred beef heifers were assigned to 1 of 4 treatment groups (n = 5 per group), defined by age at implant placement. Heifers either received an implant on Days 0, 21 or 45, or served as untreated controls. The heifers were maintained together and slaughtered at 15 mo of age, during the luteal phase of an induced estrous cycle, when reproductive tracts and blood samples were obtained. Peripheral plasma P concentrations were determined by RIA. Uterocervical wet weights were recorded, and uterine luminal flushings (ULF) were assayed for total protein. Cross-sections of uterine tissues were evaluated histomorphometrically to determine myometrial and endometrial areas and relative endometrial gland density. Treatment did not affect plasma P concentrations (3.2 ± 0.5 ng/ml). Regardless of age at treatment, neonatal PE exposure reduced uterocervical wet weight by 35% (112.8 < 173.9 ± 13.9 g; P < 0.01), myometrial area by 23% (125.3 < 162.8 ± 8.5 mm 2; P < 0.02), and endometrial area by 27% (33.3 < 45.4 ± 2.7 mm 2; P < 0.09) compared with the untreated controls. Endometrial gland density was reduced (P < 0.01) by 40% in treated heifers. This effect was related to age at implant placement. Uterine gland density was reduced (P < 0.01) by 65% in heifers treated at birth, while reductions of 22 and 33% were observed for heifers treated on neonatal Day 21 or 45, respectively. Consistently, ULF protein content was lower (P < 0.01) in the treated heifers (2.67 < 4.98 ±. 72 mg/ULF). Thus, exposure of newborn calves to PE can have profound effects on adult uterine morphology and environment, the extent of which may depend upon the developmental period when exposure occurs. The potential of such alterations to affect reproductive performance in adult beef heifers remains to be investigated.

Multiple releases of stable flies ( Stomoxys calcitrans L.) and behaviour of grazing beef cattle

A change-over statistical design with complete balance for first residual effects was used with a tethered grazing technique to evaluate the effects of arthropod ectoparasites on the behaviour of adult Angus beef cows ( Bos taurus L.; body-weight (BW), 465±30 kg) grazing vegetative tall fescue ( Festuca arundinacea Schreb. cv Kentucky 31) in screened enclosures (5 m × 5 m × 2 m). Starved laboratory-reared stable files ( Stomoxys calcitrans L.) were released into each enclosure at 15-min intervals during 1 h grazing meals. Alighted flies were counted on body surfaces and rates of fly-induced movements recorded every 15 min. Treatments were: T 1, 4×0 stable flies; T 2, 4×125 stable flies; T 3, 4×250 stable flies. Herbage dry matter (DM) mass (more than 5 cm) of the 25 cm tall sward was 3499±259 kg ha −1 and the herbage DM allowance (more than 5 cm) was 1.19±0.13 kg (100 kg BW) −1 h −1 when grazing started. Surfaces of cows assigned to T 3 supported 42 alighted flies in the first quarter and their numbers increased linearly to 53 in the last quarter of grazing meals. Front legs supported 24 alighted flies in the first quarter and their numbers rose linearly to 35 flies in the last quarter. Nine flies alighted on hind-leg surfaces in the first quarter and their numbers increased linearly to 13 in the last. Alighted flies on the trunk declined linearly from seven in the first to five in the last quarter. Few flies alighted on cows' heads. Rates of movement of heads, ears, tails, and front and hind legs, and skin twitches increased ( P<0.05) as more flies were released (T 1–T 3). Fly-induced movement rates of tail, hind-leg and skin twitches did not vary ( P>0.05) throughout grazing meals. Front-leg movement rates increased linearly ( P<0.05) as grazing meals progressed, whereas head and ear movement rates increased markedly ( P<0.05) during the last quarter of grazing meals. Rates of biting in grazing cows declined linearly ( P<0.05) as more flies were released and as grazing meals progressed. Stable flies also caused a linear decline ( P<0.01) in the time spent at grazing stations, and the number of bites and DM mass of bites taken at each feeding station. Stable flies became more disruptive of grazing processes as grazing meals progressed; increasing numbers of alighted flies, especially on the front legs, caused head and front-leg movements that interfered with prehension and biting. Herbage DM intake rates were 0.49 kg (100 kg BW) −1 h −1 and were not significantly ( P>0.05) affected by treatments, possibly because declining rates of biting were associated with increasing bite mass.

Combined effects of stocking rate and supplemental feeding level on adult beef cows grazing native rangeland in Texas.

A grazing study was conducted over 4 yr to determine the effects of stocking rate and supplemental feeding levels on intake, and BW and body condition changes by adult beef cows. Stocking rates were 12.3, 16.5, and 24.7 animal units/(100 ha.yr). Supplemental feed treatments included a negative control (NC) and 300 g/(cow.d) of CP with either 2 (L), 4 (M), or 8 (H) Mcal/(cow.d) of DE from early December to late March. Groups fed supplements (L, M, and H) lost less BW from fall to spring (P < .01) and reciprocally gained less BW from spring to weaning (P < .01) than NC cows. The L cows tended (P = .14) to lose less BW between fall and spring than M and H cows. Treatment effects on condition score were similar to those for BW change. Forage intake, estimated by measurements of fecal output, was greater by supplemented cows (P = .02); L was greater than M and H (P = .004). Increased stocking rate correlated with increased fall-to-spring BW losses (P < .002), spring-to-weaning BW gains (P < .0001), and decreased winter forage intake (P < .005). These data provide quantitative bases for the effects of stocking rate and supplemental feeding on BW and condition dynamics. Low-level feeding of a high-protein supplement can increase intake of dormant range forage, thereby increasing nutrient intake. High-level feeding of low-protein supplements seems to increase nutrient status primarily by providing supplemental nutrients. Increasing stocking rate to the reported extremes decreased forage intake and resulted in unfavorable BW and condition changes.

Face flies ( Musca autumnalis De Geer) and the behavior of grazing beef cattle

Ectoparasites, at or above certain levels, usually reduce productivity of infested livestock, however the causative processes are often poorly defined. Irritation from non-biting flies may, for example, interfere with grazing behavior and reduce herbage intake while increasing the energy diverted to support fly-induced behavior. Zero, 400 or 800 laboratory-reared adult face flies ( Musca autumnalis De Geer), which had been deprived of nutrients and water for 12 h, were released in large (5 m×5 m×2 m) screened enclosures each containing one tethered adult Angus beef cow ( Bos taurus) grazing tall fescue ( Festuca arundinacea Schreb. cultivar ‘Johnstone’). At the start of grazing, the herbage dry matter (DM) mass of the vegetative sward was 3861 kg ha −1, sward surface was at 21 cm and the pseudostem surface plane was at 6 cm. The herbage DM allowance was 1.4 kg (100 kg) −1 h −1. Surfaces of the heads of grazing cows supported about 30 alighted face flies. In addition, 20 and 30 flies alighted on the backs of cows grazing in the presence of 400 and 800 face flies per enclosure, respectively. Few face flies were present on other body surfaces. Heads of cows moved 0.0, 1.0 and 0.7 min −1 in response to the activity of 0, 400 and 800 face flies per cow, respectively. Ear movements were initiated 0.1, 22.2 and 14.3 min −1 per cow exposed to 0, 400 and 800 face flies, respectively. Panniculus reflexes (on one side of the cow's body) were triggered 0.3, 3.5 and 4.1 min −1 per cow when exposed to 0, 400 and 800 face flies, respectively. Face flies (0, 400 and 800 per cow) activated cow tail movements 0.4, 3.2 and 10.1 min −1, but did not induce movements of the front or hind legs. Rates of herbage DM intake increased linearly from 1.69 to 2.91 kg per cow h −1 (0.37–0.59 kg (100 kg) −1 h −1) as the numbers of face flies increased up to 800 per cow, largely because herbage DM intakes per bite increased from 0.74 to 1.36 g. Rates of biting in grazing cows (37 bites min −1) and the time spent at feeding stations (19 s per station) were not significantly affected by face flies. It appears that cows grazed deeper into the sward in an attempt to dislodge face flies from the muzzle and this resulted in heavier bites and, consequently, higher rates of herbage intake.

Stable flies ( Stomoxys calcitrans L.) and the behavior of grazing beef cattle

A change-over design with complete balance for first residual effects was used with a tethered grazing technique to evaluate the effects of arthropod ectoparasites on the behavior of adult Angus beef cows ( Bos taurus) (body weight (BW), 465 ± 30 kg) grazing vegetative tall fescue ( Festuca arundinacea Schreb. cultivar ‘Kentucky 31’). The three treatments were: T 1, open grazing plots with exposure to natural ectoparasite populations; T 2, grazing plots with exclosures (5 m × 5 m × 2 m) to minimize natural ectoparasite populations; T 3, similar enclosures containing 2500 laboratory-reared adult stable flies ( Stomoxys calcitrans L.). At the start of grazing, herbage dry matter (DM) mass (> 5 cm) of the 25 cm sward was 2882 kg ha −1 and the herbage DM allowance (> 5 cm) was 1.0 kg (100 kg BW) −1 h −1. Nine flies alighted on cows in open plots (T 1), very few (< 1) on cows grazing in the exclosures (T 2) and 108 stable flies alighted on cows in the enclosures (T 3). Of the latter, there were 67 on front legs, 30 on hind legs and seven on the trunk. Stable fly populations on the body surfaces of cows declined logarithmically during grazing meals. During the first part of grazing meals, stable flies induced cows (in T 3) to move their heads (8 times per minute), and to lift their front legs (8 times per minute) and hind legs (3 times per minute). Stable flies also induced ear movements (12 per minute), tail movements (69 per minute) and skin twitches (25 per minute). Rates of stable fly-induced behavior declined logarithmically during grazing meals. Cows in T 1, T 2 and T 3 visited 4.2, 3.9 and 3.1 feeding stations per minute, respectively, but rates of herbage DM intake were not affected by the presence of stable flies ( P > 0.05) and averaged 0.35 kg (100 kg BW) −1 h −1. In the absence of stable flies (T 2), rates of biting of cows declined logarithmically from 46 to 30 bites min −1. Cows subjected to stable flies (T 3), however, started grazing at 19 bites min −1 and ended grazing meals at 26 bites min −1. Mean herbage DM intakes per bite were 833, 694 and 1011 mg for T 1, T 2 and T 3, respectively.

Protein-Energy Malnutrition in Ruminants

Protein-energy malnutrition occurs when feed is provided to ruminant livestock in insufficient quantity, quality, or both. The clinical syndrome that results from protein-energy malnutrition is not difficult to recognize, but it may be difficult to convince owners of the diagnosis. Development of clinical signs, such as recumbency and hypothermia, may occur rapidly owing to the sudden failure of homeostatic mechanisms that maintain the supply of cellular fuels. The ruminant is unique in its response to malnutrition because ruminal microorganisms become malnourished just as their host does. Ruminal maldigestion hastens the onset of clinical signs and makes recovery very difficult and prolonged. Clinical signs of PEM are similar in adult beef cattle, dairy cattle, sheep, and goats; however, the typical history of affected animals varies for each of these species. Neonatal ruminants may also be severely affected with PEM if they do not receive sufficient colostrum and milk. Definitive diagnosis of primary PEM requires necropsy of an affected animal. Diagnosis of PEM in an individual animal usually indicates a herd or flock problem that requires immediate attention. If the affected individual is already recumbent, then treatment will likely be difficult and unsuccessful. Changes in management of the herd or flock that involve ensuring adequate feed intake, minimizing cold and social stress, and meeting the animal's specific nutritional requirements will prevent PEM and maximize production.

Expression of troponin T in atria and ventricles of avian and mammalian hearts

The expression of troponin T in atria and ventricles of adult chicken, rabbit and beef hearts has been studied by two dimensional electrophoresis of soluble extracts from these tissues. The monoclonal antibody, T1/61, has been used to detect the presence of troponin T in the chicken samples. In the chicken only one form of troponin T has been found which is resolved into two spots that probably are due to phosphorylated and non phosphorylated forms. The gels of chicken atria and ventricles are identical with the same patterns, not only of troponin T but also of tropomyosin and myosin light chains. In rabbit and beef the position of troponin T can be located by comparison with the chicken. In the beef it is possible that two forms are present but in the rabbit there appears to be only one. The gels of atria and ventricles of rabbit and beef hearts show differences only in the myosin light chains whereas the expression of tropomyosin is the same. In beef, beta-tropomyosin is found in both tissues. On the evidence of these gels there are no differences in the expression of troponin T or tropomyosin between the atria and ventricles of any of the hearts studied.

Energy requirements for the penetration of heads of domestic stock and the development of a multiple projectile.

The forces and kinetic energy required to penetrate the isolated heads of calves, adult beef cattle, sheep and red deer with a metal probe the same diameter as the bore of an experimental pistol were determined. Approximately 16 and 127 Joules were required to penetrate the heads of adult sheep and cattle, respectively. Using these data a 10 g projectile, consisting of 49 lead pellets and a lead disc in a polyethylene sleeve, was constructed. This projectile, when fired by a charge sufficient to produce a muzzle velocity of 165 m/second, had sufficient kinetic energy to penetrate the heads and brains of cattle, sheep, horses and deer. The projectile was fired from a new design of humane killer with a spring loaded barrel and fitted with a silencer. After penetration of the frontal bones the projectile fragmented and the kinetic energy of its individual particles were insufficient for them to penetrate the opposite side of the head of any of the animals, including one-week-old calves. Fragmentation also caused more brain damage and inhibition of spinal reflexes than a solid free bullet or captive bolt. It is suggested that the use of such a projectile for the emergency slaughter of animals is less hazardous than a solid free bullet and is easier to use and more effective than either a solid free bullet or captive bolt. The projectile was not suitable for killing adult pigs because of problems associated with the frontal sinus.

Isolation and characterization of a cDNA clone for bovine cytochrome c oxidase subunit IV.

We have isolated a cDNA clone for the precursor to subunit IV of bovine cytochrome c oxidase (ferrocytochrome c:oxygen oxidoreductase, EC 1.9.3.1). A cDNA library was constructed from poly(A)+ RNA of adult beef liver by insertion of cDNA into the plasmid vector pBR322. Transformants were screened by colony hybridization with two mixtures of [32P]-labeled synthetic oligodeoxyribonucleotides. We screened 20,000 transformants with a mixture of heptadecamers complementary to all 16 possible sequences encoding amino acids 98-103 and obtained two cDNA clones encoding subunit IV amino acid sequences. We determined the DNA sequence of the larger (416 base-pair) insert, which contains the coding sequence for amino acids 1-107 of the mature protein and an NH2-terminal extension (presequence). The deduced amino acid sequence of the mature protein is identical with the previously determined protein sequence: the sequence of the NH2-terminal extension contains a potential initiator methionine at amino acid -22 from the NH2-terminus of the processed protein. The presequence is quite basic and contains several arginines, including one at the processing site. No hydrophobic region analogous to that found in bacterial and eukaryotic signal peptides is present, but there are homologies with other mitochondrial protein presequences, which may include a common signal for their destination and processing.

Serum pepsinogen levels andOstertagia ostertagipopulations in clinically normal adult beef cattle

Serum pepsinogen levels and Ostertagia ostertagi populations in clinically normal grass-fed bullocks were investigated in three groups of 10 prime cattle aged between 2.5 and 2.75 years slaughtered in late summer (February), early autumn (March) and late autumn (May) respectively. Apart from occasional foci of mucosal hyperplasia abomasa were grossly normal. Serum pepsinogen levels ranged between 0.2 and 2.5 i.u./l with group means of 1.4, l.5 and 1.3 i.u./l. O. ostertagi counts ranged between 0 and 5,194 with group means of 734,630 and 701 worms. The composition of the worm populations varied with a higher proportion of adults recovered in February and very few worms from most cattle in March, suggesting the termination of a parasite generation. An increase in numbers of early fourth-stage larvae in May indicated exposure to a new generation. These changes were not reflected in the pepsinogen levels. The findings are discussed in relation to the adequacy of the pepsinogen assay as a diagnostic aid in field infections, animal age, and correlations between pepsinogen levels and parasite populations.

Collagen type distribution in the mammalian left ventricle during growth and aging.

Left ventricular collagen of rats aged 1,4,8, and 24 months, as well as young and adult pigs and beef, was successively extracted with neutral salt and dilute acid solutions and limited pepsin digestion. The distribution of type I and III collagen molecules in pepsin-solubilized collagen was analyzed with sodium dodecyl sulphate polyacrylamide gel electrophoresis in the presence of 3.6 M urea, under nonreducing and reducing conditions. Yields of dilute-acid-soluble collagen ad neutral-salt-soluble collagen were extremely low (0.3-0.8%, and less than 0.3% of total starting collagen, respectively), indicating the presence of an extensive interchain and intermolecular cross-linking network in left ventricular tissue of young and mature mammals. Comparison of protein patterns in electrophoresis gels indicated that myocardial collagen consists primarily of type I collagen molecules. The components of type III collagen also occurred in all investigated preparations, in varying and consistently lower proportions. The ratio of type III to type I collagen changed during postnatal growth and aging.

Johne’s Disease: A Retrospective Study of Vaccinated Herds in Great Britain

SUMMARY The use of Johne’s disease vaccine in cattle in Great Britain since its introduction in 1964 is briefly reviewed. In 1975 the vaccine was being used in 462 herds of which 68 (14·8%) were beef herds, 381 (82·5%) dairy and 13 (2·7%) were mixed dairy and beef herds. This represented a vaccination rate of three herds per 1000 herds containing adult dairy or beef cattle in Great Britain. The vaccine has been used in herds with relatively high rates of disease and particularly in dairy herds. A retrospective study of disease incidence in 231 cattle herds, in which all calves had been vaccinated over a period of at least four years and which had remained closed with no changes in breed or herd type, indicated that freedom from disease was achieved after an average of four years. Clinical cases occurred in 9·7% of herds in the tenth year following the start of vaccination. The number of years to freedom from disease was apparently influenced by management practices; provision of piped water supplies and the culling of offspring of clinical cases being beneficial. The incidence of disease prevaccination, herd size and breed were not found to affect the time for herds to become free of clinical disease.

Species- and age-dependent changes in the relative amounts of cardiac myosin isoenzymes in mammals

In mice, rabbits, and pigs, two basic types of cardiac myosin isoenzymes were found by electrophoresis of native molecules: a fast-migrating form with high Ca 2+-dependent ATPase activity and a slow-migrating form with low activity. According to the nomenclature of J. F. Y. Hoh, P. A. McGrath, and P. T. Hale (1978, J. Mol. Cell. Cardiol. 10, 1053–1076) these forms are called, respectively, V1 and V3. In all species, myosin was essentially V3 during fetal life, while V1 appeared around the time of birth. There were species differences in adults: mice remained V1, while rabbits and pigs returned to V3 after 3 weeks of age. Adult dog, beef, and human myosins were also composed of the V3 form only.

Lysosomal hydrolases in neuronal, astroglial, and olidodendroglial enriched fractions of rabbit and beef brain.

Arylsulfatases A, B, and C, beta-galactosidase, and acid phosphatase were assayed in neuronal, astroglial, and oligodendroglial fractions isolated from adult rabbit and beef brains. The specific activities of all acid hydrolases were lower in beef cells compared to rabbit cells. The lysosomal enzymes of the rabbit neuronal fraction showed 10--25 time higher activities than the oligodendroglial fraction and 5-fold higher activities than the astroglial fraction. In beef brain, the specific activities of these enzymes were similar in oligodendroglia and astrocytes but 4--10 times lower than in neurons. The low activity of arylsulfatase A and beta-galactosidase in oligodendroglial cells may suggest that the low turnover of cerebroside and sulfatide in myelin may be regulated in part by the enzymes that catalyze their degradation.