A simple method for the demonstration of factors in bovine colostrum capable of causing anaemia in lambs reared free from maedi on bovine colostrum

Previous studies demonstrated that the anaemia encountered in lambs reared on bovine colostrum and a milk substitute was associated with the presence of immune complexes on lamb erythrocytes. In the present study the usefulness of a panel of 20 sheep sera for the detection of "anti-sheep" factors in bovine colostrum by double immunodiffusion in agarose was investigated. Utilising this method, 353 batches of bovine colostrum have been examined, 132 of which were declared safe for use in the rearing of lambs. When fed to lambs, only 2 samples (1.5%) caused anaemia as compared with up to 20% before this test was introduced. Experiments designed to determine whether the bovine colostra, declared anaemia-prone, would indeed cause anaemia when fed to lambs, showed our method to fully discriminate between safe and unsafe colostra for the rearing of lambs. In a follow-up collaborative study, set up to cover most of the Netherlands, the general validity of the test system described was demonstrated, using 114 batches of safe colostrum to feed 723 lambs. Further experiments are needed to determine the exact nature of the factor(s) involved in this phenomenon.     

Vaccination of cows with clostridial antigens and passive transfer of clostridial antibodies from bovine colostrum to lambs

Two Friesian cows were used to attempt to produce colostrum containing a high concentration of clostridial antibodies which could be fed to newborn lambs in order to passively transfer immunity to diseases caused by clostridia. One cow was given a commercial multicomponent clostridial sheep vaccine in two successive pregnancies and the second cow in one pregnancy. The first cow produced a low concentration of epsilon antitoxin (Clostridium perfringens, type D) in its blood and colostrum after the first course of three injections of vaccine. A higher concentration was produced by cow 2 after a course of six injections and by cow 1 after a further course of four injections in its next pregnancy. Two hundred ml of colostrum from cow 1 (after the second course of vaccine) was given to 12 newborn colostrum-deprived lambs. All showed a high concentration of antitoxin 48 hours later. The lambs were actively immunised by injections of the same clostridial vaccine at three and nine weeks or six and 12 weeks old and all produced sufficient antitoxin to protect up to slaughter at 24 weeks. It is concluded that colostrum from cows vaccinated with sheep clostridial antigens can be fed to protect lambs passively.     

Anaemia in housed lambs

Anaemia was detected in housed lambs by clinical and haematological investigation. Conjunctival pallor was used as a clinical test for anaemia and the results indicate that this has high specificity (91 per cent to 95 per cent) and low sensitivity (53 per cent to 55 per cent). The haematological results indicated a non-regenerative anaemia with low packed cell volume, red blood cell count and haemoglobin. In a subset of lambs examined biochemically, anaemia was associated with low serum iron concentration and low serum iron binding: cobalt levels were within normal ranges and blood copper levels were slightly raised. At present it is unclear whether this is a primary or secondary iron deficiency.     

Effects of feeding ewe colostrum, cow colostrum or ewe milk replacer on plasma glucose in newborn lambs

The plasma concentration of glucose was monitored for six hours in lambs fed either ewe colostrum, cow colostrum or milk replacer by stomach tube at one hour of age. The feeding of ewe colostrum resulted in an elevation of the mean (+/- se) plasma glucose concentration from 2 . 6 +/- 0 . 3 mmol/litre before feeding to 7 . 3 +/- 0 . 92 mmol/litre three hours after feeding and this elevation was maintained. A similar rise was observed in the lambs fed cow colostrum but this was of shorter duration. A marked hyperglycaemia was observed after the feeding of milk replacer with a maximum value of 23 . 4 +/- 1 . 33 mmol/litre three hours after feeding. The practical implications of these results are discussed.     

Specific immunoglobulins in serum of newborn lambs fed with a single dose of colostrum containing anti-peroxidase IgG

The apparent efficiency of absorption and the decrease of specific colostral IgG after its passage into the blood stream were determined in newborn lambs fed with a single dose of colostrum containing anti-peroxidase IgG at 30 minutes, 12 hours and 24 hours after birth. When colostrum was given at 30 minutes after birth, a value of 16.9+/-4.0 per cent of anti-peroxidase IgG ingested appeared in lamb circulation. This percentage was reduced to 9.8+/-0.8 per cent when the feeding was done at 12 hours after birth and no specific IgG was detected in lambs fed at 24 hours after birth. The concentration of anti-peroxidase IgG in lambs' serum declined quickly within 96 hours of age to about 48 per cent of the initial value, and afterwards the level decreased slowly reaching a value of 10 per cent at 32 days of age. This behaviour probably reflects the protein distribution and use of absorbed antiperoxidase IgG.     

Passive protection of calves against experimental infection with Salmonella typhimurium

Cows were vaccinated with formalin-killed Salmonella typhimurium approximately seven weeks and two weeks before parturition to investigate whether passive immunity could protect their calves against experimental S typhimurium infection. After birth the calves were left with their dam for 48 hours and then separated and fed cold, stored colostrum from their own dam for a further eight days. Oral challenge five days after birth with 10(8) S typhimurium did not result in the death of these calves even when they had absorbed little colostrum. Mortality was reduced to 22 per cent in calves which sucked from vaccinated dams and were then fed colostrum from unvaccinated cows and to 50 per cent in calves born to unvaccinated cows and later fed colostrum from vaccinated animals. Calves which sucked from a vaccinated dam and then received stored colostrum from the same cow excreted salmonellas for significantly shorter periods after challenge and were less often infected at necropsy 28 days after inoculation. Protection was not correlated with the levels of O or H agglutinating antibodies in serum, which were at a maximum 24 hours after sucking and then slowly declined. There was no evidence of an active antibody response in the serum. Measurement of the O and H response of cows after vaccination indicated that the vaccination schedule could be improved. The highest levels of agglutinating antibody were measured between two and three weeks after the first vaccination and there was only a minimal response to the second vaccination before parturition.(ABSTRACT TRUNCATED AT 250 WORDS)     

Colostral transmission of maedi visna virus: sites of viral entry in lambs born from experimentally infected ewes

Maedi visna virus (MVV) vertical transmission in sheep via infected colostrums is a very important route of infection in lambs. To verify colostral transmission and to study early viral entry in lambs, colostrum samples, and small intestine and mesenteric lymph nodes of lambs born from experimentally infected ewes were examined by histopathology, immunohistochemistry (IHC) and in situ hybridisation (ISH) studies. In particular, newborn lambs were naturally fed maternal colostrum and humanely killed at 10, 24, 48, 72, 96 h and 7 and 10 days after birth; two caesarian-derived lambs served as uninfected controls. No lesions suggestive of MVV infection were found, but marked immunoreactions for MVV capsid antigen (CA, p28) were detected in lambs fed maternal colostrum and in macrophages cultured from colostrum. IHC results in lambs suggest an initial viral absorption by intestinal epithelial cells at the tip of the villi, passage to mononuclear cells in the lamina propria and involvement of ileum Peyers' patches and mesenteric lymph nodes, with different staining patterns depending on infection times. ISH on intestinal sections of the 72 h lamb revealed the presence of proviral DNA in epithelial cells at the tip of the villi, suggesting a role for these cells in early MVV replication. The results contribute to knowledge about the pathogenesis of ovine lentivirus infection suggesting that the small intestine and mesenteric nodes are the sites of entry and propagation of MVV in lambs fed colostrums from infected ewes.     

Effect of colostrum treated by heat on immunological parameters in newborn lambs

Seventeen newborn lambs were fed with untreated colostrum (group A) and 18 lambs were fed with colostrum treated by heat (56 °C, 30 min) (group B). Blood samples were obtained at seven time points from day 0 to 38 of life. Clinical status and body weight were recorded and serum protein fractions and IgG levels were determined in blood. Phagocytosis of neutrophils from the lambs and opsonic capacity of their serum were examined using a flow cytometry method. As an indicator of in vivo cellular immunity, reactions to intradermal injection of phytohemagglutinin (PHA) were examined at 8 and 16 days of age. There were no clinical signs of disease and no significant differences in body weight between groups. Lambs from group B had lower total protein initially and lower γ-globulin and IgG levels until day 32 compared to lambs from group A (P < 0.01). Heat treatment of colostrum had no significant effect on serum opsonic capacity or phagocytosis by neutrophils and these functions increased with age. However, responses to PHA in lambs from group B were lower (P < 0.01) than group A at day 8 of life, but not at day 16, suggesting that cellular immunity was affected by the treatment of colostrum. These results showed that colostrum treated by heat impaired cellular and IgG levels in lambs, but not phagocytic function. However, these changes did not affect the health or performance of the lambs.     

Role of thiamine status in sulphur induced polioencephalomalacia in sheep.

The effects of excess dietary sulphur were studied in sheep supplemented and unsupplemented with thiamine. The diets contained either 0.19 per cent sulphur (LS) or 0.63 per cent sulphur (HS) in combinations with 14 mg kg-1 thiamine (LB1) or 243 mg kg-1 thiamine (HB1). A total of 56 two-month-old lambs were used. Groups consisting of nine, nine, 22 and 16 lambs were fed LS-LB1, LS-HB1, HS-LB1 and HS-HB1 diets, respectively for 14 weeks. Out of 22 lambs fed the HS-LB1 diet, seven lambs developed neurological signs between the third and eighth week of the trial. Two of these lambs died, three that were in extremis were euthanased, and two recovered completely. All clinically affected animals had extensive malacic lesions in the cerebral cortex, midbrain and brainstem. None of the lambs from the LS groups or HS-HB1 group developed clinical signs. Several clinically normal lambs from the HS-LB1 group had necrotic lesions in their brains at gross and microscopic examination. Supplementation with dietary thiamine prevented development of clinical signs, but did not totally prevent development of microscopic brain lesions. Brain thiamine concentration, transketolase activity and thiamine pyrophosphate (TPP) effect were not different (P greater than 0.05) among groups. There was a strong effect (P less than 0.0001) of dietary thiamine supplementation on blood thiamine concentration and TPP effect. Blood thiamine concentration was higher whereas TPP effect was lower in the thiamine supplemented sheep. Blood and tissue thiamine concentrations in sheep exposed to high dietary sulphur did not indicate either systemic or local thiamine deficiency per se. Increased TPP effect in sheep fed the HS-LB1 diet indicated mild to moderate metabolic thiamine deficiency. Thiamine inadequacy may be an effect of an increased requirement for thiamine in animals exposed to excess dietary sulphur.     

Effects of maternal nutrition on the availability of energy in the body reserves of fetuses at term and in colostrum from Scottish Blackface ewes with twin lambs

Ewes carrying twin fetuses were maintained during late pregnancy on a uniformly high plane (n = 22), a uniformly low plane (LP) (n = 24) or a low plane increasing to a high plane (n = 14) of nutrition. Seven ewes at each nutritional level were killed at 142 days of gestation and the liver and muscle glycogen and body lipid concentrations of the fetuses were determined. The rest of the ewes lambed naturally at about 145 days and the colostrum yields were obtained by hand milking after oxytocin injections during the first 18 hours after birth. The lactose, lipid and protein concentrations of colostrum were determined. Undernutrition in the LP group did not apparently affect the body concentrations of available glycogen, reduced available body lipid by about 47 per cent and reduced the lactose, lipid and protein available in colostrum during the first 18 hours by about 50 per cent. Refeeding previously underfed ewes to a high plane during the last five to 10 days of pregnancy did not improve the available reserves of glycogen or lipid in the lambs but did increase the yields of colostral constituents by about 30 per cent. The relative contributions of body reserves and colostral constituents to the maintenance of high, medium and low metabolic rates in lambs from different groups was assessed. It was concluded that under normal field conditions refeeding undernourished ewes during the last weeks of pregnancy would improve only marginally the survival potential of the lambs and that most lambs would be compelled to draw on their body glycogen reserves in order to maintain heat production during the first 18 hours after birth, even when they consumed all the available colostrum.     

Effect of feeding 5 per cent glucose solution or milk replacer to newborn piglets on intestinal permeability to macromolecules

Newborn piglets were fed either a 5 per cent glucose/electrolyte solution or a commercial milk replacer for 24 or 36 hours before they were given colostrum, or they were given colostrum after birth. The effects of these treatments on their ability to absorb macromolecules was assessed by measuring the uptake of 125I-polyvinylpyrrolidone (125I-PVP) and the increases in the concentrations of total proteins and immunoglobulins in serum. The piglets which received colostrum at birth absorbed 50 per cent of a test dose of 125I-PVP within six hours, and there was a rapid increase in the concentration of immunoglobulins in their blood. The piglets which received the 5 per cent glucose/electrolyte solution absorbed 40 per cent of the test dose of 125I-PVP administered 24 or 36 hours after birth and nearly normal quantities of immunoglobulins, but the piglets given the milk replacer absorbed only 10 per cent of the test dose of 125I-PVP, and virtually no immunoglobulins.     

Effects of gestational plane of nutrition and selenium supplementation on mammary development and colostrum quality in pregnant ewe lambs

To examine effects of nutritional plane and Se supplementation on colostrum quality and mammary development, individually fed, pregnant Rambouillet ewe lambs were allotted randomly to 1 of 6 treatments in a 2 x 3 factorial arrangement. Main effects included dietary Se level, which began at breeding (d = 0) [adequate Se (9.5 mug/kg of BW) vs. high Se (81.8 mug/kg of BW)], and plane of nutrition, which began at d 50 of gestation [60% (RES), 100% (CON), and 140% (HIGH) of requirements]. Upon parturition, lambs were immediately separated from dams and weighed. Three hours after lambing, colostrum yield was determined, and samples were obtained for components and immunoglobulin G (IgG) analysis. Ewes were slaughtered within 24 h of parturition, and mammary tissues were collected for determination of alveolar secretory epithelial cell proliferation index and luminal area. Gestation length was reduced (P < 0.01) in HIGH ewes compared with RES and CON ewes. Although birth weights were reduced (P < 0.01) in RES and HIGH compared with CON ewes, there was little effect of diet on placental size. Mammary gland weight was reduced (P /= 0.15) on mammary gland weight, colostrum quantity, or IgG concentration in pregnant ewe lambs. Improper nutrition from mid to late pregnancy in ewe lambs altered colostrum quality and quantity and reduced offspring birth weight, which may have negative implications for lamb health and survival during the early postnatal period.     

Differentiation of dogs with regenerative and non-regenerative anaemia on the basis of their red cell distribution width and mean corpuscular volume

The red blood cell distribution width (RDW), which provides a quantitative measure of the heterogeneity of the red cell population (anisocytosis) in the peripheral blood, the mean corpuscular volume (MCV) and a regression model combining both variables were used to assess their predictive accuracy in differentiating 51 dogs with regenerative anaemia from 92 dogs with non-regenerative anaemia, which had been diagnosed on the basis of the corrected reticulocyte count A classification tree analysis was constructed to generate an optimum set of diagnostic rules to differentiate between the two types of anaemia. Seventy-four dogs with a normal haemogram were used as controls. An increase of 1 per cent in the RDW and of 1 fl in the MCV increased the odds of an anaemic dog suffering from regenerative anaemia by factors of 1.3 and 1.14, respectively. By the classification tree, 78 per cent of anaemic dogs with a RDW of 16.25 per cent or less would be expected to have non-regenerative anaemia. With a RDW over 16.25 per cent, an MCV of 68.2 fl was the cut-off between dogs expected to have regenerative (71 per cent) or non-regenerative (75 per cent) anaemia. The RDW and MCV are measured by most automatic haematology analysers and may give the first indication of the bone marrow response of an anaemic dog. However, different electronic counters give different normal values of the RDW and MCV.     

Eradication of ovine pulmonary adenocarcinoma by motherless rearing of lambs

The principles of maedi-visna eradication programmes were applied to a field trial for the eradication of ovine pulmonary adenocarcinoma (OPA). In two maternal flocks the prevalence of gross and histological lesions in slaughtered animals was 18.3 per cent and 29.8 per cent, respectively. The lambing period was supervised for three consecutive years from 1999 to 2001, during which the lambs were taken away from their mothers at birth, deprived of maternal colostrum, and hand-reared away from other sheep. Over the three-year period, 322 hand-reared animals, mainly male lambs between 10 and 14 months old, were slaughtered; their lungs were examined grossly, 52.5 per cent of them were examined histologically, and 105 samples of caudal mediastinal lymph nodes were examined by PCR. No OPA tumours were detected in the slaughter specimens from the derived flock, but one lamb had histological lesions in one lung location; intrauterine transmission was ruled out in this case. No clinical OPA has subsequently been observed in the hand-reared flock. Bronchoalveolar lavage samples from the breeding stock were examined by PCR in order to rule out further subclinical cases of OPA. No Jaagsiekte retrovirus was detected in any of the 488 samples.     

Colostrum intake by dairy calves

AIMS: To determine which clinical parameters could be used to identify calves with low serum immunoglobulin levels and to examine the influence of cow and calf behaviour on colostrum intake. METHODS: Blood samples were taken from 74 dairy calves after they were separated from their dams, and analysed for serum gamma glutamyltransferase (GGT) activity. Physical and behavioural measurements were taken for 57 of these calves at this time. The behaviour of 2 1 dairy cows and their calves was observed between birth and the time the calves were separated when a blood sample was taken from 17 of them and analysed for GGT. RESULTS: Low serum GGT activities (below 200 U/l GGT), indicating low serum immunoglobulin levels, were found in 45% of the group of 74 calves. The calves which had not received colostrum were not easy to distinguish from those that had on the basis of physical or behavioural features. The amount of time that the 2 1 calves spent with their dams before being separated ranged from 1.2 to 24.9 hours. Thirty-three per cent of these calves had not sucked within this time. Of the calves that did suck, 79% did so within 6 hours of birth. CONCLUSIONS: About one half of New Zealand dairy calves may not receive colostrum from their dams even when they are together for up to 24 hours. Most calves that are going to suck of their own accord will do so within 6 hours of birth. CLINICAL SIGNIFICANCE: Dairy calves should be removed from their dams after 6 hours and fed colostrum to guarantee that they receive sufficient immunoglobulins.     

Abomasal size and emptying time in healthy lambs and in lambs affected by watery mouth

Contrast radiography (barium sulphate suspension fed by stomach tube) was used to assess abomasal profile area (a reflection of tone in the abomasal wall) and the rate of abomasal emptying in healthy lambs aged four to 144 hours and in lambs affected by watery mouth. In healthy lambs abomasal profile area increased from 15.1 +/- 0.56 cm2/kg at four hours of age to 23.1 +/- 1.07 cm2/kg at 24 to 48 hours (P less than 0.001). There was no change up to 48 to 72 hours but after this age there was a substantial decrease to 12.8 +/- 0.76 cm2/kg at 120 to 144 hours (P less than 0.001). The rate of abomasal emptying decreased as abomasal profile area increased. Complete emptying of the abomasum was observed within three hours of feeding in the majority of lambs aged four hours (seven out of eight) and 120 to 144 hours (13 out of 16) but only in a minority of lambs aged 24 to 48 hours (one out of 11). In lambs affected by watery mouth (mean age [+/- se] 33 +/- 2.8 hours, n = 34) abomasal profile area was greater and the rate of abomasal emptying was slower than in healthy lambs aged 24 to 48 hours. These findings confirm the previous suspicion that watery mouth is associated with an impairment of gut motility. Abomasal emptying time was prolonged in lambs aged four hours when either ewe or cow colostrum was included with the contrast medium. A similar effect was observed in lambs aged 24 to 48 hours when cow colostrum was included. The castration of lambs aged four hours with rubber rings immediately before the administration of contrast medium had no effect on the rate of abomasal emptying.     

Relative contribution of colostrum from Maedi-Visna virus (MVV) infected ewes to MVV-seroprevalence in lambs

Maedi-visna virus (MVV) seroprevalence associated with consumption of colostrum from seropositive ewes was investigated in 276 housed lambs from birth to 300 days-old. At birth, lambs were allocated to five experimental groups according to the maternal MVV-serological status, source and mode of feeding colostrum (bovine or ovine and bottle fed or suckled from the dam) and type of horizontal MVV-exposure (raised with the dam or separately with other lambs). The risk of being seropositive at 300 days-old was associated with feeding ovine colostrum from seropositive ewes and increased with intake of bottle-fed ovine colostrum and was higher in lambs separated from their dams and raised with other experimental lambs compared to lambs raised with their dams. Approximately 75-87% of ELISA-positive results in lambs that had ovine colostrum was attributable to colostrum itself. However, approximately only 16% of naturally raised and 29-61% of bottle-fed ovine colostrum lambs were ELISA-positive as a result feeding ovine colostrum. These results confirm that ovine colostrum from seropositive ewes can be a major source of MVV but its overall contribution to seroprevalence in natural conditions is relatively low, and shows that horizontal MVV transmission can be an important source of infection in new-born lambs.     

Immunoglobulin derived from bovine plasma as a replacement for colostrum in newborn lambs

Newborn lambs (n = 45) at the Agricultural Research Institute of Northern Ireland were fed either 50 grams of commercial lamb milk replacer or 50 grams of commercial colostrum replacer (bovine origin) in 200 ml of water four times during the first 24 hours of life or were given ad libitum access to the ewe. Total plasma protein at 24 hours of age was highest in lambs allowed to suckle the ewe (76.9 g/L). However, by 14 days of age, there were no differences in plasma protein levels among the three treatments. Bovine IgG was measured in lambs fed colostrum replacer and ovine IgG was measured in other lambs. Mean plasma IgG concentrations at 24 hours of age were 0.7 (milk replacer), 18.0 (colostrum replacer), and 26.6 (dam's milk) g/L. Bovine IgG administered orally to newborn lambs was adequately absorbed, and circulating IgG concentrations were sufficiently maintained throughout this study.     

Diarrhoea in dairy calves reduced by feeding colostrum from cows vaccinated with rotavirus

Forty-two dairy calves remained with their dams for two days after birth, and then were removed to a calf rearing shed. Calves were allocated to three groups for the next 14 days, and received twice daily either whole milk, whole milk with a 10 per cent supplement of pooled normal bovine colostrum or whole milk with 10 per cent supplement of colostrum from cows vaccinated with rotavirus. A natural outbreak of diarrhoea occurred, affecting 28 of the 42 calves. Feeding immune colostrum delayed the onset of diarrhoea, and reduced its incidence, duration and severity. Live weight gains were consequently improved. The group fed normal colostrum had diarrhoea intermediate in severity between that of control calves and those fed immune colostrum. The aetiology of the diarrhoea was complex, with calves excreting rotavirus, enteropathogenic Escherichia coli and cryptosporidia.     

The immunoprophylaxis of of rotavirus infections in lambs.

The effect of colostrum or serum feeding on subsequent rotavirus infections was investigated in neonatal gnotobiotic lambs. Immunity after feeding colostrum did not depend on absorption of passively acquired antibody into the circulation. Protection against clinical disease depended on the volume of colostrum ingested. The protection afforded by feeding serum was specific, since serum free of rotavirus antibody failed to confer protection. Immune serum fed at a rate of 2.5 ml per kg twice daily protected against rotavirus infection. Also, it was shown by intraperitoneal inoculation of immune serum that protection could occur in the absence of ingested antibody, presumably by transfer of antibody into the gut. The implications of these findings for immunoprophylaxis of rotavirus diarrhoea in lambs and calves are discussed.