Uptake of colostral immunoglobulins by the compromised newborn farm animal.

Neonatal mortality is very high in farm animals (approximately 10%) and disease resistance is greatly influenced by an adequate passive immunisation just after birth. In piglets, foals, calves and lambs, the intestinal absorption of immunoglobulins from their mother's colostrum occurs mainly by a non-specific endocytosis of macromolecules, but the details of the absorption process, and the mechanisms regulating its cessation after 1-2 days of colostrum exposure, remain poorly understood. In both normal and 'compromised' (premature, growth-retarded, hypoxic, lethargic) newborn farm animals, the intestinal capacity to absorb macromolecules is influenced by both diet- and animal-related factors. Thus, macromolecule uptake is severely reduced in response to premature birth and when macromolecules are to be absorbed from diets other than species-specific colostrum. On the other hand, fetal growth retardation, in vitro embryo production, or a stressful birth process are unlikely to reduce the ability of the intestine to absorb immunoglobulins from colostrum. More knowledge about the diet- and animal-related factors affecting intestinal immunoglobulin uptake will improve the clinical care of 'compromised' newborn farm animals. The present text gives a brief introduction to the process of intestinal immunoglobulin absorption in large farm animals and describe some recent results from the author's own studies in pigs, calves and lambs.

Effects of dietary vitamin E supplementation during late pregnancy on lamb mortality and ewe productivity.

OBJECTIVE: To determine the effect of feeding vitamin E to ewes during late pregnancy on lamb mortality and ewe productivity. DESIGN: Prospective study. ANIMALS: 1,302 mature Rambouillet and Targhee ewes. PROCEDURE: During a 3-year period, approximately 430 ewes/y were randomly allocated to 2 groups; supplement-group ewes were fed additional vitamin E and control-group ewes were not. Beginning approximately 3 weeks before the first expected lambing date, ewes were fed 2.3 kg (5 lb) of alfalfa-grass hay/d and 0.23 kg (0.5 lb) of barley-based pellets/d with or without supplemental vitamin E. Pellets that were supplemented contained 1,450 mg of DL-alpha-tocopherol acetate/kg (658 mg/lb) of feed and provided an additional 330 IU of vitamin E/ewe/d. Selenium was incorporated into a trace mineral salt and fed free choice to all ewes throughout pregnancy. RESULTS: Supplemental vitamin E had no effect on ewe weight, body condition score, fertility, or prolificacy. In ewes that lambed in the early part of the lambing season, vitamin E supplementation significantly reduced lamb mortality, compared with no supplementation (12 vs 17%, respectively). Consequently, supplement-group ewes had significantly greater total body weight of lambs per ewe at the time of weaning, compared with control-group ewes. Differences were not observed between ewe groups in lamb mortality or total body weight of lambs per ewe at the time of weaning when ewes lambed during the late part of the lambing season. CLINICAL IMPLICATIONS: If ewes are fed additional vitamin E3 weeks before parturition, those that lamb in the early part of the lambing season may have low lamb mortality and, thus, higher total body weight of lambs per ewe at the time of weaning.

Effect of cobalt supplementation on serum vitamin B12 levels, weight gain and survival rate in lambs grazing cobalt-deficient pastures.

The effect of cobalt supplementation on serum vitamin B12, growth rate and survival rate was measured in controlled field experiments with Texel twin lambs of the same sex, grazing cobalt-deficient pastures. The non-supplemented lambs had lower serum vitamin B12 concentrations than their supplemented brothers or sisters. During the experiments more lambs died in the non-supplemented than in the supplemented group. At the end of the experiments supplemented lambs weighed (mean live weight) 7.2, 9.5, and 11.0 kg more than non-supplemented lambs in 1991, 1992, and 1993, respectively. Sex-related differences in weight gain and survival rate were observed.

Thrombocytopenic purpura in lambs given bovine colostrum.

Newborn lambs which had been given colostrum from a single cow developed thrombocytopenia and seven died. The clinical signs included purpura, haemoglobinuria, melaena, dullness and lethargy. The lambs died at one to two days old. Post mortem examination revealed widespread haemorrhages throughout the body. Lambs given small amounts of colostrum developed a transient thrombocytopenia but did not die.

Thrombocytopenia in lambs fed with bovine colostrum.

Artificially reared lambs, fed with bovine colostrum, died within 48 hours after birth, showing thrombocytopenia and extensive haemorrhages on autopsy. The mechanism behind was not fully understood, but experimental immunization of young cattle against sheep red blood cells, carried out five years earlier on the same farm, may have played a role.

Farm investigations of anaemia in lambs caused by feeding cow colostrum.

The deaths on nine farms of lambs which had been fed cow colostrum as a substitute for ewe colostrum were investigated. Of 105 lambs which received cow colostrum, 65 (61.9 per cent) showed clinical signs of anaemia and 42 (40 per cent) died. The signs of anaemia usually appeared when the lambs were between eight and 12 days old. The most significant post mortem finding was the appearance of the bone marrow which was cream or grey rather than the normal bright red. The types of treatment which were given are summarised. Whey from samples of the colostrum fed to the lambs was tested for its effect on sheep red blood cells. Haemolysis or agglutination of the red cells occurred with some, though not all, of the samples which caused anaemia.

Heliotropium europaeum poisoning of sheep with low liver copper concentrations and the preventive efficacy of cobalt and antimethanogen.

In a field experiment in the Mallee district of Victoria, Merlno xBorder Leicester ewes and wethers grazed Heliotropium europaeum (heliotrope) over periods of 3 to 4 months in 4 successive years. By the end of the second year 12% (14 of 120) of the sheep had died; after 4 years the loss attributable to heliotrope was between 18% and 35%. Mortality was not affected by intraruminal treatment with cobalt or antimethanogen. At the end of the experiment the highest concentration of copper in the liver was 1.95 mmol/kg wet weight (approximately 413 micrograms/g dry weight). The relatively low mortality from primary heliotrope poisoning and the low concentration of copper in the liver of sheep grazing the plant are discussed in relation to the contrasting situation that prevails in the Riverina area of New South Wales. The importance of local environmental factors in the management of heliotrope grazing by sheep is emphasised, particularly in relation to the number of seasons in which the plant may be a major component of the diet.

Effects of management system, legume feeding and anthelmintic treatment on the performance of lambs in north Sumatra.

Sixty-four lambs in North Sumatra were used in a factorial experiment comprising two systems of management (grazing and stall-feeding), four levels of legume supplementation (0, 250, 500 and 1,000 g/d Pueraria javanica) and two anthelmintic treatments (none and albendazole every four weeks). The experiment lasted five months. The mortality rate for lambs not given anthelmintic was 28%, significantly higher (P less than 0.05) than for animals given anthelmintic which had zero mortality. Anthelmintic treatment increased growth rate from only 2 g/d to 29 g/d (P less than 0.05) and reduced faecal egg count from 1,700 epg to 270 epg. When not given anthelmintic grazing lambs had a higher mortality rate (38%) than stall-fed lambs (19%) but this difference was not significant. When given anthelmintic grazing lambs has a slightly higher growth rate (32 g/d) than stall-fed lambs (26 g/d). System of management had no apparent effect on egg count. Legume supplementation reduced the egg count of lambs not given anthelmintic but had no significant effect on mortality or growth rate.

Pyrrolizidine alkaloid poisoning of sheep in New South Wales.

Pyrrolizidine alkaloid poisoning of sheep in New South Wales was reviewed, based on the records of the New South Wales Department of Agriculture's Regional Veterinary Laboratories. The plant species causing significant mortalities were Echium plantagineum and Heliotropium europaeum. The syndrome of hepatogenous chronic copper poisoning was more frequently diagnosed than primary pyrrolizidine alkaloid poisoning, particularly when grazing E. plantagineum. The data indicated that adult crossbred ewes were the most commonly affected class of sheep.

Passive transfer of colostral immunoglobulins from ewe to lamb and its influence on neonatal lamb mortality.

The transfer of immunoglobulin G (IgG) and immunoglobulin M (IgM) from ewe to lamb was quantitated to determine the occurrence of failure in passive transfer. Concentrations of IgG and IgM in ewe serum did not correlate with those in the colostrum. Colostrum from all ewes contained abundant amounts of immunoglobulins when compared with serum values, with IgG being selectively concentrated over IgM. Absorption through the intestinal tract of the lamb appeared to be a nonselective process, lacking predilection for IgG and IgM. All lambs tested 24 hours after birth absorbed colostral immunoglobulins to some extent; however, 13 (14%) of 91 clinically normal lambs demonstrated some failure of passive transfer. In contrast, failure of passive transfer was found in 27 (46%) of 59 lambs dying of natural causes between 24 hours and 5 weeks of age. Evidence presented emphasizes the importance of absorption of adequate amounts of immunoglobulins to enable the newborn lamb to survive the first few weeks of life.

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.