The piglet as a model for B cell and immune system development.

The ability to identify factors responsible for disease in all species depends on the ability to separate those factors which are environmental from those that are intrinsic. This is particularly important for studies on the development of the adaptive immune response of neonates. Studies on laboratory rodents or primates have been ambiguous because neither the effect of environmental nor maternal factors on the newborn can be controlled in mammals that: (i) transmit potential maternal immunoregulatory factors in utero and (ii) are altricial and cannot be reared after birth without their mothers. Employing the newborn piglet model can address each of these concerns. However, it comes at the price of having first to characterize the immune system of swine and its development. This review focuses on the porcine B cell system, especially on the methods used for its characterization in fetal studies and neonatal piglets. Understanding these procedures is important in the interpretation of the data obtained. Studies on neonatal piglets have (a) provided valuable information on the development of the adaptive immune system, (b) lead to important advances in evolutionary biology, (c) aided our understanding of passive immunity and (d) provided opportunities to use swine to address specific issues in veterinary and biomedical research and immunotherapy. This review summarizes the history of the development of the piglet as a model for antibody repertoire development, thus providing a framework to guide future investigators.

Effects of graded levels of Fusarium toxin contaminated wheat in diets for fattening pigs on growth performance, nutrient digestibility, deoxynivalenol balance and clinical serum characteristics.

A dose response study was carried out with pigs in order to examine the effects of increasing dietary deoxynivalenol (DON)-concentrations on performance, clinical serum characteristics, nutrient digestibility and DON-metabolism. For this purpose, wheat contaminated naturally with Fusarium toxins was incorporated into pig diets at increasing proportions to give calculated dietary DON-concentrations of 0, 2.3 and 4.6 mg/kg during the starter period of phase 1 (14 d) of the experiment, and 0/0, 1.2/1.4, 2.3/3.7 mg/kg starter/grower diet during phase 3 (56 d) of the experiment. Each diet was tested on 16 pigs of both sexes with an initial average live weight of approximately 28 kg. A recovery phase (phase 2, 21 d) was intercalated between phase 1 and 3 of the growth experiment where all groups were fed with the uncontaminated control diet since some pigs exposed to the highest dietary DON-concentration during phase 1 nearly completely refused the offered feed. Affected pigs completely recovered during this phase. In phase 3, when diets with lower DON-concentrations were fed, no differences in performance could be detected. Serum clinical characteristics (enzymes indicating liver damage, total protein, immunoglobulins) did not respond to increasing DON-concentration in the diets. DON-concentration in serum increased in a dose-response-related manner as dietary DON-concentration increased. However, this parameter was not or only weakly correlated to any of the examined performance parameters or serum characteristics. Also, nutrient digestibility of the diets and N-retention were not affected by treatments with the exception of crude fat digestibility which was not consistently influenced. Concentration of DON and its metabolite de-epoxy-DON increased in urine with increasing dietary DON-concentration in a strongly linearly related fashion. The proportion of the excretion of de-epoxy-DON of the total urinary excretion of DON plus de-epoxy-DON rose linearly up to approximately 4%. Total recovery of DON plus de-epoxy-DON as percentage of DON-intake varied between 45 and 57% and was not influenced by dietary DON-concentration. Only a very small fraction of approximately 0.1% of ingested DON was recovered in faeces.

Effects of graded levels of Fusarium toxin contaminated maize in diets for female weaned piglets.

A dose response study was carried out with piglets to examine the effects of increasing amounts of Fusarium toxins in the diet on performance, clinical serum characteristics, organ weights and residues of zearalenone (ZON) and deoxynivalenol (DON) and their metabolites in body fluids and tissues. For this purpose, Fusarium toxin contaminated maize (1.2 mg ZON and 8.6 mg DON per kg maize) was incorporated into a maize based diet for piglets at 0, 6, 12.5, 25 and 50% at the expense of control maize. The experimental diets were tested on 100 female piglets allotted to 20 boxes (five animals per box) covering a body weight range of 12.4 +/- 2.2 kg to 32.5 +/- 5.6 kg. Voluntary feed intake and, consequently, body weight gain of the animals receiving the highest proportion of Fusarium toxin contaminated maize were significantly decreased while the feed conversion ratio was not affected by the treatment. The mean weight of the uterus related to the body weight of the animals of the same group was increased by almost 100% as compared to the control. For this group, significantly decreased values of total serum protein were determined, while the serum activity of the liver enzyme glutamate dehydrogenase and the serum concentration of the follicle stimulating hormone were decreased for all treatment groups receiving 6% contaminated maize or more in the diet. Serum concentrations of immuneglobulins were not consistently altered by the treatment. Corresponding to the dietary exposure, increasing concentrations of ZON and alpha-zearalenol were detected in the bile fluid, liver and in pooled urine samples. The metabolite beta-zearalenol was detected only in bile fluid. The total concentration of ZON plus its metabolites in bile fluid correlated well with the diet contamination (r = 0.844). DON was found in serum, bile fluid and pooled urine samples while de-epoxy-DON was detected only in urine. The serum concentration of DON correlated well with the respective toxin intake 3-4 h prior to slaughtering (r = 0.957). For all mentioned analyses of residues it has to be noted that toxin residues were detectable even if negligible concentrations were present in the diet.

[ACTH stimulation test for the determination of salivary cortisol and of cortisol responses as markers of the training status/fitness of warm-blooded sports horses]. / ACTH Stimulationstest und Bestimmung von Cortisol im Blut und Speichel zur Bewertung des Trainingszustands/der Kondition beim Warmblutpferd.

Previous work (Marc et al., 2000) suggested that plasma cortisol responses to treadmill exercise or ACTH injection are a reliable marker for performance evaluation in warmblood horses. For practical purposes blood sample collections and treadmill exercise tests are somewhat troublesome and time consuming. The goal of this study was thus to evaluate the use of saliva for cortisol determination (by direct EIA) as a marker for performance and to investigate the reliability and repeatability of plasma cortisol responses to a single i.v. injection of ACTH (50 micrograms or 250 micrograms). Furthermore, the effect of training horses for 8 weeks 3 times per week covering the same distance (increasing from 3.5 km during the first week to 8 km during the last week) either by trotting (approximately 240 m/min) or by cantering (375 m/min) was investigated. For this purpose initially ten four-year-old Hannovarian geldings, all reared in the same State stud, were used. Mean overall correlation between salivary cortisol and plasma cortisol concentrations was 0.64 when samples of various points of time were used. However, in spite of attempts to standardize saliva sample collection, correlation between salivary cortisol levels and plasma cortisol levels at distinct points of time in different tests were low and significant (r = 0.85, p < 0.02) only in one test. Thus, salivary cortisol measurements for diagnostic purposes are not reliable or useful. The repeatability of plasma cortisol responses to ACTH for untrained and trained horses were r = 0.86 and r = 0.8 respectively (p < or = 0.01 and p < or = 0.05 respectively). Training horses either by trotting or cantering did not affect the cortisol response either to treadmill exercise or to stimulation by ACTH. It is concluded that the relationship between salivary cortisol levels and plasma cortisol levels is not close enough to allow the use of salivary cortisol determination as marker of the training status/fitness of horses. The repeatability of the cortisol response to ACTH is similar to the cortisol response to treadmill exercise. Based on plasma cortisol responses to ACTH or treadmill exercise training horses by cantering at low speed is not superior to training by trotting for the fitness of horses.

Deoxynivalenol in pigs: An exclusive effect on the appetite?

A feeding-trial was conducted to determine the effects of a deoxynivalenol (DON)-contaminated diet in growing pigs. DON was added as either the purified toxin or as naturally contaminated wheat. Growth performance, biochemical and hematological parameters and DON-transformation through intestinal bacteria were monitored throughout the study. Epithelial tissues along the gastro-intestinal tract were also examined for pathological changes and selected enzyme activities (oxoglutarat dehydrogenase, alanine-amino-transferase). There were no differences among the dietary treatments in all parameters measured except for feed intake and weight gain in the naturally contaminated diets fed ad libitum. Effectsin vivo could not be explained exclusively by cytotoxicity of DON foundin vitro. These observations may reflect the presence of other unidentified (toxic) compounds in the naturally contaminated grain or the influence of further factors. In future studies synergistic/additive interactions with substances promoting appetite should be taken into consideration.

Comparison of freezing and lyophilizing for preservation of colostrum as a source of immunoglobulins for calves.

Lyophilizing was compared to freezing as a method of colostrum storage. Eight lots of colostrum from the first milking were divided into two equal parts; one was frozen, and the other was lyophilized. Twenty-two newborn calves were divided into two groups and fed either 2 L of frozen and thawed colostrum or 2 L of reconstituted lyophilized colostrum. The calves were bled at 12, 18, 24, and 72 h after feeding, and levels of the immunoglobulins IgG1, IgG2, IgM, and IgA were determined with a radial immunodiffusion assay, in colostrum and sera. The mean concentration of individual immunoglobulin isotypes in the sera of calves fed either frozen or lyophilized colostrum did not differ significantly. Calves fed from the same lots of colostrum had similar immunoglobulin concentrations in their sera, irrespective of the method of storage. All immunoglobulin isotypes were absorbed with equal efficiency from frozen and lyophilized colostrum as determined by calculation of the absorption coefficient.

Electron spectroscopic imaging of antigens by reaction with boronated antibodies.

Two small homogeneous markers for electron spectroscopic imaging (ESI) containing eight dodecaborane cages linked to a poly-alpha, epsilon-L-lysine dendrimer were synthesized; one of these was made water soluble by the attachment of a polyether. The markers were coupled to the sulfhydryl group of (monovalent) antibody fragments (Fab') by a homobifunctional cross-linker. While the coupling ratios of the poorly water-soluble compound did not exceed 20%, the polyether-containing variant reacted quantitatively. Its suitability for immunolabelling was tested in a study of the mechanism of the transcellular transport of an administered heterologous protein (bovine serum albumin, BSA) through ileal enterocytes of newborn piglets by endocytotic vesicles in comparison to conventional immunogold reagents. The post-embedding technique was employed. The boronated Fab' gave rise to considerably higher tagging frequencies than seen with immunogold, as could be expected from its form- and size-related physical advantages and the dense packing of BSA in the vesicles. The new probe, carrying the antigen-combining cleft at one end and the boron clusters at the opposite end of the oval-shaped conjugate, add to the potential of ESI-based immunocytochemistry.

Immunocytochemistry by electron spectroscopic imaging using a homogeneously boronated peptide.

A linear all-L-oligopeptide containing five carboranyl amino acids (corresponding to 50 boron atoms) was synthesized and specifically attached to the free thiol group of monovalent antibody fragments F(ab)'. The boronated immunoreagent was used for the direct post-embedding detection of somatotrophic hormone in ultrathin sections of porcine pituitary embedded in Spurr resin. The specific boron-labelling of secretory vesicles in somatotrophs was detected by electron spectroscopic imaging and confirmed by conventional immunogold labelling run in parallel. In comparison with immunogold, boron-labelled F(ab)'-fragments showed higher tagging frequencies, as was expected; the small uncharged immunoreagents have an elongated shape and carry the antigen-combining structure and the detection tag at opposite ends, thus allowing for high spatial resolution in electron spectroscopic imaging.

[The quantitative passage of immunoglobulins from the intestine into the blood vessels in newborn lambs]. / Untersuchungen zum quantitativen Ubergang von Immunoglobulinen aus dem Darm in die Blutbahn neugeborener Lämmer.

A trial with 69 lambs examined the effect of the feeding regime on the transfer of colostral immunoglobulins from the intestinal lumen to the circulating blood. The lambs received 125 ml of bovine colostral milk per kg birth weight at each feeding in the first 24 hours after birth. There were four experimental groups. Feeding intervals were either 2 or 6 hours and the milk was administered with or without doubling the fluid volume by addition of tap water. Serum concentrations of IgG1, IgG2, IgM and IgA were measured during the experimental period and the transport efficiency index for each isotype was calculated. The transport efficiency index represents the relationship between the amount of immunoglobulin administered in colostral milk and the concentration measured in the blood. Feeding in 2 hour intervals produced maximum immunoglobulin concentrations at 30 hours, while 6 hour feeding intervals achieved the same maximal levels at 24 hours. The relative proportions of the four immunoglobulin isotypes measured in the blood were unaffected by the feeding interval. Doubling the fluid volume administered while holding the absolute amount of colostral milk constant, resulted in a disproportionate increase in blood IgG1 concentration as compared to the other isotypes. Concentrations for IgG2, IgM and IgA remained essentially the same as those achieved with undiluted colostral milk. The feeding regimes tested did not affect endogenous immunoglobulin synthesis, growth rate or the health of the lambs.

[The "waiting period" for follow-up administration of bovine colostrum to newborn lambs]. / Untersuchungen über "Wartezeiten" mit anschliessender Verabreichung von Rinderkolostralmilch bei neugeborenen Lämmern.

Extent and duration of the permeability of the small intestine of newborn lambs for intact proteins from cow's colostrum was analyzed in five groups of animals. Cow's colostrum in quantities of 200 ml/kg birth weight, was offered in 3-hr intervals for 24 hrs, beginning either immediately after birth or after fasting, for 12 and 24 hrs respectively. In two groups each either 5% glucose solution or saline was offered to the fasting animals. The following results were obtained: 1. All lambs fed immediately after birth drank eagerly. The intake in all fasting groups dropped between 12 and 24 hrs of the feeding period. 2. While the duration of the permeation of the small intestine for intact proteins remained unaffected by the various regimens, fasting with or without supplementation decreased the maxima. 3. The decrease in protein permeation was class-depending as demonstrated by the lower levels of bovine IgM in the sera of fasting lambs. 4. The permeability of the small intestine for proteins was substantially reduced by 5% glucose. The difference between fasting lambs or lambs with saline substitution was minimal. 5. All lambs fed immediately after birth survived. The losses in the other groups amounted to 29% after 12 hrs of starving, 33% after 24 hrs of starving, 30% after starving with glucose supplementation and 50% after saline solution. 6. The surviving animals showed no differences in weight gain.

Passage of a heterologous protein through ileal enterocytes of newborn piglets: immunolabelling of bovine serum albumin at the light- and electron microscopic level.

The passage of bovine serum albumin through ileum enterocytes of neonatal pigs was studied by light microscopy with indirect immunoperoxidase and by electron microscopy with post-embedding direct immunogold methods. Vacuoles filled with the heterologous protein were seen as early as 10 min after the administration of either bovine serum or solutions of bovine serum albumin by gavage. The sizes of vacuoles increased with time, their electron densities and immunoreactivities were at variance. The formation of albumin-containing vacuoles was independent of the concentration of the solutions fed, ranging from 1 to 7%. Bovine serum albumin becomes discernible in the capillaries at 4 h after feeding. By then, the intact albumin transported through enterocytes amounted to more than 10% of the circulating plasma proteins. Of several thousand enterocytes screened in the whole study only one--from the piglet 4 h after feeding--contained lysosomes.

[Necessary care of newborn lambs using ovine colostrum. 2. Duration of administration]. / Erforderliche Versorgung neugeborener Lämmer mit Schafskolostralmilch. 2. Mitteilung: Verabreichungsdauer.

Sheep colostrum, pooled from 0-12 h milkings, was fed to 38 newborn lambs for either 6, 12, 18 or 24 hrs after birth. The influence of the duration of feeding periods on the transintestinal passage of immunoglobulins, the growth performance, the loss rate and the onset of immunoglobulin synthesis were investigated by monitoring the serum concentrations of IgG1, IgG2, IgM and IgA during months 1 through 9 of life. Feeding of 3 portions of 100 ml at 2 h intervals resulted in lower serum levels of Ig's than the extension of the feeding to 12 x 100 ml every second hour. There was, however, no difference in the onset of endogenous Ig production between both groups. Growth performance and the loss rate were also identical.

[Necessary provision of newborn lambs with sheep colostrum]. / Erforderliche Versorgung neugeborener Lämmer mit Schafskolostralmilch. 1. Mitteilung: Verabreichungsintervall.

Twenty new-born lambs of each of the breeds Schwarzkopf, Texel and Finnish were fed with 600 ml of pooled colostrum (0-12 h) on the first day of life. The total allocation was fed in portions ranging from 25 to 150 ml at intervals of 1, 2, 3, or 6 hours. The effect of the different intervals and portion volumes on the transintestinal passage of immunoglobulins, the onset of endogenous synthesis, the growth performance of the lambs and the mortality rate was investigated. The concentrations of IgG1, IgG2, IgM and IgA in the sera were analyzed over the course of a nine-week period. 1. The extent of passive immunization by transintestinal passage remained essentially unaffected by different feeding schedules. 2. There was also no effect on the onset of endogenous Ig synthesis. 3. Growth performance and mortality rate likewise showed no discernible differences.

[The absorption of colostral immunoglobulins in newborn piglets. III. Influence of the duration of colostrum administration]. / Untersuchungen über die Absorption der kolostralen Immunglobuline bei neugeborenen Ferkeln. III. Mitteilung: Einfluss der Verabreichungsdauer der Kolostralmilch.

The gastrointestinal tract of newborn piglets is permeable for intact immunoglobulins ingested with the colostrum. The duration of this passage was investigated by administering hourly rations of 25 ml of either porcine or bovine colostrum for 6, 12, 18 or 24 hrs after birth. The plasma concentrations of the subclasses porcine IgG, IgM and IgA or bovine IgG1, IgG2, IgM and IgA were determined at 12, 18 and 24 hrs after birth and on days 3 and 6. Feeding periods of 6 hrs resulted in plasma Ig levels of the same order of magnitude as observed in natural rearing. These levels were not substantially increased after prolonged feeding. The 6% gain from 6 to 12 feedings seen with porcine colostrum as compared with a gain of 24% for bovine colostrum points at an earlier closure of the intestinal wall for the species-specific proteins. There was no further increase of Ig permeation after 12 hourly feedings. Growth performances and losses were identical in all groups.

[The absorption of colostral immunoglobulins in newborn piglets. II. Effect of water or glucose solutions on the permeability of the newborn intestine]. / Untersuchungen über die Absorption der kolostralen Immunoglobuline bei neugeborenen Ferkeln. II. Mitteilung: Einfluss von Wasser oder von Glukoselösung auf die Durchlässigkeit des neugeborenendarmes.

The extent and the duration of the passage of intact proteins from the intestinal lumen into the bloodstream of newborn piglets was investigated. A total of 48 piglets from 4 litters were used in groups of 6 animals per experiment. The piglets were removed from the sow immediately after birth and placed in individual boxes of an automatic feeding device. Liquids were offered in trays, access to which was controlled by electronically operated gates. Volumes of 25 ml were allotted in hourly intervals. Porcine colostrum (6 x 25 ml) or bovine colostrum (24 x 25 ml) were either offered immediately, or after a 24 h fasting period without or with access to tap water. Two groups received 24 hourly rations of a 13 % glucose solution prior to the onset of feeding with porcine and bovine colostrum, respectively. The plasma levels of immunoglobulins were assessed by radial diffusion in blood samples drawn from a subcutaneous abdominal vein. The passage of intact proteins ceases between 12-18 hrs after the onset of feeding. Both the time course of the passage and the maximal levels achieved are unaffected after previous fasting or after tap water allowances only for 24 hrs. Previously fed glucose solution--in contrast--closes the gut barrier to subsequently ingested proteins. There was no difference in the postexperimental weight developments between groups.

[The absorption of colostral immunoglobulins in newborn piglets. I. Effect of time from birth to the first feeding]. / Untersuchungen über die Absorption der kolostralen Immunglobuline bei neugeborenen Ferkeln. I. Mitteilung: Einfluss der Zeit von der Geburt bis zur ersten Nahrungsaufnahme.

The effects of a delayed onset of feeding on the absorption of intact immunoglobulins from the small intestines was investigated in newborn piglets by using an automatic device ("artificial sow"). Fasting periods extended to a maximum of 24 hours and were followed by 12 hourly allotments of 25 ml of sow colostrum. The concentrations of immunoglobulins G, A and M were analyzed in plasma samples drawn before and after the onset of feeding. The capacity for Ig-absorption was not impaired by the fasting. The same plasma levels of 12 and 18 hours after the onset of feeding were obtained in piglets fed immediately after birth as observed with individual variations in all experimental groups, for which we could find no explanation. Our results indicate, that the absorptive ability of the intestinal epithelia for immunoglobulins is not timed from birth but rather from the onset of feeding.

Maternal-neonatal immunoregulation: suppression of de novo synthesis of IgG and IgA, but not IgM, in neonatal pigs by bovine colostrum, is lost upon storage.

Fifty-four neonatal pigs were allotted to 4 groups and reared in an electrically controlled automatic feeding device (autosow). Each group was reared on a different pool of bovine colostrum: fresh, stored 1 month, stored 6 months, and stored 8 years. Bovine and porcine immunoglobulins in the sera of these pigs, and in a group of conventionally reared pigs, were measured periodically during the first 42 days after birth. The maximal concentration of absorbed bovine immunoglobulin was reached between 12 and 18 hours and equaled or exceeded the amount of porcine immunoglobulin absorbed by the conventionally reared pigs. Large differences in the concentrations of the bovine immunoglobulin isotypes among the various pools of colostrum were positively correlated with concentration of these isotypes in the sera of the neonatal pigs fed these pools. Relative to their concentrations in colostrum, approximately 41% of the IgG1, 55% of the IgG2, 29% of the IgM, and 67% of the IgA was absorbed. The IgA was absorbed the best and IgM was least absorbed. Significant trends or differences in absorption were not observed among groups. Neonatal pigs given fresh colostrum, which had a higher fat content, had significantly more weight gain (P less than 0.05). This occurred, despite the fact that the fresh colostrum had the lowest concentration of bovine immunoglobulin. Serum half-lives for bovine IgG1 and IgG2 were significantly less than for porcine IgG (P less than 0.05), whereas the half-lives for bovine and porcine IgM and IgA were similar. De novo-synthesized immunoglobulins were detectable in serum after 6 days; IgM concentrations reached a maximum at 15 days in neonatal pigs given stored, but not fresh, colostrum.(ABSTRACT TRUNCATED AT 250 WORDS)

[Variations in the concentrations of the immunoglobulins IgG1, IgG2, IgM and IgA in sheep. 2. Changes in the blood of lambs of different breeds and crossbreeds during the course of the rearing period]. / Variationen in den Konzentrationen der Immunglobuline IgG1, IgG2, IgM und IgA beim Schaf. 2. Mitteilung: Veränderungen im Blut der Lämmer verschiedener Rassen und Rassekreuzungen im Verlauf der Aufzuchtperiode.

The sera of 188 lambs from seven breed groups were analyzed for the concentrations of IgG1, IgG2, IgM and IgA by radial immunodiffusion using monospecific antibodies. From each lamb, 14 blood samples were drawn before and 5 samples after weaning. The following results were obtained: 1. Immunoglobulins could not be detected in sera drawn before the first intake of colostrum. 2. In normally suckling lambs, the peak concentrations of maternal immunoglobulins are attained at 0-18 hrs after birth. They can be assessed in a single blood sample drawn between 18 and 24 hrs. 3. The half-life times of maternal immunoglobulin in lamb sera are 11 days for IgG1, 7 days for IgG2, 6 days for IgM and 18 hours for IgA. 4. The absolute peak heights relate to the amounts of colostrum ingested before 12-18 hrs after birth. 5. The decline of maternal immunoglobulins in lamb sera over-laps with the onset of lamb immunoglobulin synthesis. Renewed rises of concentrations are observed for IgG2 after week 2, for IgM after week 3 and for IgG1 after week 7. The concentrations of IgA remain at the low levels characteristic for the serum of grown sheep. 6. The role of immunoglobulin synthesis in suckling lambs is only briefly and to a small extent reduced after weaning.

[Variations in the concentrations of the immunoglobulins IgG1, IgG2, IgM and IgA in sheep. 1. Changes in the blood serum and in the milk of sheep of different breeds and cross-breeds during lactation]. / Variationen in den Konzentrationen der Immunglobuline IgG1, IgG2, IgM und IgA beim Schaf. 1. Mitteilung: Veränderungen im Blutserum und in der Milch der Schafe verschiedener Rassen und Rassekreuzungen im Verlauf der Laktation.

A total of 103 ewes from the breeds Black mutt., Texel, Finn. L., Heidschnucke and the crossbreeds Texel x Finn. L. and Black. mutt. x Finn. L. was studied. Blood samples were drawn at days 1, 7, 21 and 42 and milk samples at the 4th, 12th, 24th and 72nd hour after the onset of lactation and subsequently on days 7, 21 and 42. The concentrations of the immunoglobulins IgG1, IgG2, IgM and IgA were assayed in serum and milk. The following results were obtained: 1. The total immunoglobulin contents in the serum was not significantly different between breeds. 2. All ewes showed a rise in serum immunoglobulin concentrations by about one third over the first six weeks of lactation. Between 50-60% of this increase were on the account of IgG1. 3. The serum concentration of IgG1 and IgG1 rose as of the third day, those of IgM as of day 21 after lambing. 4. The rise in serum immunoglobulin concentration continued after the weaning of the lambs. 5. The ratio of IgG1 to IgG1 in ewe serum was 2:1. 6. The immunoglobulin concentration in milk dropped sharply on the first day of lactation, followed by a continuous, more gradual decrease over the entire course of lactation. A terminal rise, as observed in sows, could not be detected. 7. The ratio of IgG1:IgG2 : IgM : IgA in the whey changed from 85 : 1 : 12 : 2 on day one to 70 : 7 : 12 : 11 on the last day of lactation. 8. While characteristic trends in immunoglobulin patterns in the sera of ewes over the course of lactation are clearly discernible, it is not possible to denote "normal" values.

Composition of sow milk during lactation.

The composition of sow colostrum and milk was quantitated in 25 sows at 14 time points throughout lactation. All animals belonged to the same experimental herd of German Landrace, farrowed within 4 d, and were of various lactation numbers and various litter sizes. In the first 6 h of lactation colostrum total solids (TS) and protein contents were higher, while fat and lactose contents were lower than in mature milk. Decreased total protein and whey protein contents and concomitantly increased fat and lactose content, with nearly unchanged TS levels, indicate transition from colostrum to mature milk. The high protein content of colostrum was largely due to immunoglobulin (Ig). During the first 6 h, IgG accounts for nearly all the protein in colostrum but plays a decreasing role in sow milk as lactation proceeds. After 2 wk, IgA levels begin to increase and at the end of lactation, IgA constitutes 40% of the total whey protein. No influences of lactation number and litter size on milk composition could be ascertained in this study.