The impact of dietary sodium on the incidence of nursing sickness in mink dams and on the average litter biomass of 28 and 42 day old kits was studied. One group (n = 115 including 12 barren females) was given a standard feed mixture with a natural content of 0.53 g NaCl/MJ and another group (n = 115 including 8 barren females) was given the same feed mixture supplemented with NaCl to a final content of 1.00 g/MJ. The average dam weight at weaning was significantly lower (P < 0.001) and the incidence of nursing sickness during the last part of the lactation period 3 times higher in the nonsupplemented group. The average litter biomass at weaning did not differ between the 2 experimental groups. A number of biochemical markers of preclinical nursing sickness, e.g. plasma aldosterone and osmolality, Na+ and Cl concentrations in plasma and urine, were studied during the last part of the lactation period and at weaning in 20 dams of the nonsupplemented group, in 10 dams of the salt supplemented group and, for comparison, in 5 + 5 barren females on the day corresponding to day 34 after parturition in nursing mink. The nonsupplemented group had significantly lower concentrations of sodium and chloride in plasma and urine and a significantly higher concentration of plasma aldosterone as compared to the salt supplemented group. Distinct signs of relative salt deficiency and preclinical nursing sickness thus characterized the nonsupplemented group throughout this period, while more blurred hints of electrolyte imbalances were noticed in the sodium chloride supplemented group at weaning. A beneficial effect of salt supplementation on the incidence of nursing sickness was shown; however, it remains unclear whether salt deficiency can cause nursing sickness or whether salt acts as an appetite stimulant preventing inanition and the development of the disorder.

The productivity and well-being of animals can be substantially affected by stress. This is particularly true in the case of beef calves that are subjected to a multitude of stressors over a short period during the first year of life. Perhaps the most often studied stress-responsive variable has been blood corticosteroid concentrations. Factors such as age, gender, genetics, and degree of prior experience, can influence how an animal perceives and responds to a given stressor. Few studies have tried to control these variables, and accordingly, many conflicting results have been published regarding the impact of various stressors on cortisol response. We measured baseline plasma cortisol concentration over a 44-day study in Bos indicus and Bos taurus calves. Plasma cortisol values in Bos indicus calves were higher (32.60 +/- 0.66 ng/ml) than values in calves of Bos taurus (25.81 +/- 0.76) breeding. A precipitous decrease in cortisol concentration was observed 7 days after transport stress in all calves. Baseline cortisol concentration did not provide any indication of the intensity of the various stressors. However, significant differences were readily observed after ACTH administration. On the basis of cortisol secretion, stresses of transport and weaning were similar and were the most stressful to calves, regardless of genotype.

A survey to detect Streptococcus suis serotype 2 in 1,716 weaned pigs was done in Quebec. Forty-nine sow herds were included in this survey: in 26 herds, S suis serotype 2 had been isolated during the preceding 12 months and in 23 herds (control), the organism had not been detected during a previous study. Swab specimens of the nasal cavity and tonsils of pigs were obtained for bacteriological culture, and S suis serotype 2 was easily detected by the use of brain-heart infusion agar containing a Streptococcus-selective supplement and 5% goat antiserum raised against S suis serotype 2. After measurement of the diameter of the precipitation zone of 539 isolates, a slide agglutination test was performed to identify the S suis serot ype 2 isolates. The mean precipitation zone diameter obtained for group S suis serotype 2 was larger (P less than 0.001) than that for the group designated as "others." With slide agglutination test results as reference and on the basis of discriminant analysis to simulate detection of S suis serotype 2, 93.1% of all isolates were correctly classified, using the precipitation zone diameter as unique classification criterion. Relative specificity was 94.5% and relative sensitivity was 88.7%. Use of the precipitation zone diameter on a quantitative basis led to the proposal of a simple and reliable technique to screen swine herds for S suis serotype 2 in weaned pigs. Nasal and tonsillar swab specimens were obtained and analyzed concurrently for S suis serotype 2. The organism was found in both sites in only 20.4% of 103 carrier pigs. Nasal and tonsillar specimens yielded 55.3 and 65%, respectively, of all S suis serotype 2 isolates. Statistically significant difference was not observed between the numbers of S suis serotype 2 isolated from each site. Both sites permitted the recovery of S suis serotype 2 isolates; it was advantageous to use nasal and tonsillar swab specimens to determine the most reliable evaluation of S suis serotype-2 carrier status in weaned pigs.

We attempted to determine whether weaning is required for induction of diarrhea in pigs with postweaning enterotoxigenic Escherichia coli infection. Three-week-old newly weaned pigs and their suckling littermates were inoculated with the K88+ enterotoxigenic E coli strain M1823B. Fourteen of 21 weaned and 12 of 20 suckling pigs were genetically resistant to intestinal adhesion by the K88+ strain of E coli; they remained healthy, and gained weight at similar rates. Both groups of K88-resistant pigs gained weight faster, and shed fewer bacteria of strain M1823B in their feces, than did their K88-susceptible counterparts. Diarrhea developed in K88-susceptible pigs in the weaned (6 of 7 pigs) and suckling (4 of 8 pigs) groups, and 1 of the 4 affected suckling pigs died from complications resulting from diarrhea. The incidences of diarrhea, weight gain rates, and the numbers of strain M1823B shed in feces of susceptible weaned and suckling pigs were not significantly (P > 0.05) different. Diarrhea scores of susceptible weaned pigs were significantly (P < 0.02) higher than those of susceptible suckling pigs on the second day after inoculation. In this experimental model, it was concluded that weaning is not required for induction of diarrhea, but may modestly increase its severity.

Objective—To determine whether selection for the homozygous A136R171 genotype that confers resistance to classic scrapie infection negatively affects production traits in sheep. Animals—996 commercial lambs obtained from 2 flocks at separate locations across 3 consecutive years. Procedures—Genotyping at codon 136 and 171 was performed by use of commercially available testing or a single-nucleotide polymorphism assay. Carcass data were collected without knowledge of genotype approximately 24 hours after slaughter by an experienced grader. The model to analyze associations between prion protein (PRNP) genotype and production traits was based on genotype, breed, or both as fixed effects and days on feed as a covariate. Results—Average daily gain was significantly associated with only combined codons 136 and 171. In flock 1, weaning average daily gain was significantly greater in AA136 sheep than heterozygotes; the difference between QR171 and RR171 sheep, compared with QQ171 sheep, were not significant although QR171 and RR171 sheep had higher values. However, in flock 2, average daily gain was significantly greater in AV136 sheep than AA136 sheep and in QR171 sheep than QQ171 sheep. Conclusions and Clinical Relevance—Findings suggest there is an advantage for average daily gain in lambs with an arginine allele at codon 171, but there were no other genotype effects on production traits. Thus, selection for the resistant arginine allele at codon 171 to comply with USDA scrapie eradication guidelines should not be detrimental to lamb production in commercial flocks. Effects of codon 136 on average daily gain were ambiguous.

We quantified the effect of passive immune status on pre- and postweaning health and growth performance of calves raised in a beef production environment. Blood samples were collected at postpartum hour 24 from 263 crossbred calves for determination of plasma protein (PP) and serum IgG concentrations. Serum IgG concentration was classified as adequate (> 1,600 mg/dl), marginal (800 to 1,600 mg/dl), or inadequate (< 800 mg/dl). Plasma protein concentration was classified as adequate (greater than or equal to 4.8 g/dl) or inadequate (< 4.8 g/dl). Morbidity and mortality events in the study population were monitored from birth to weaning, and after weaning throughout the feeding period. The lowest concentrations of serum IgG and PP were observed among calves that experienced morbidity or mortality prior to weaning. Calves that experienced morbidity in the feedlot had lower 24-hour PP values, but had IgG concentration similar to that in calves that were not observed to be ill during the feeding period. Calves classified as having inadequate IgG concentration were at greater risk of preweaning mortality (odds ratio [OR] = 5.4), neonatal morbidity (OR = 6.4), and preweaning morbidity (OR = 3.2), compared with calves classified as having adequate IgG concentration at 24 hours. Calves classified as having inadequate PP concentration at 24 hours had a greater risk of morbidity (OR = 3.0) and respiratory tract morbidity (OR = 3.1) while in the feedlot, compared with calves classified as having adequate PP concentration. The effects of 24-hour passive immune status on calf growth were indirect through effects on morbidity outcomes. Morbidity during the first 28 days of life was associated with a 16-kg lower expected weaning weight. Respiratory morbidity in the feedlot resulted in a 0.04-kg lower expected mean daily gain. Thus, passive immune status at postpartum hour 24 was an important determinant of health before and after weaning, and was indirectly associated with calf growth during the same periods.

Three-week-old weaned and colostrum-deprived neonatal (< 1 day old) pigs were inoculated to determine the pathogenicity of 2 enterotoxigenic Escherichia coli isolates that do not express K88, K99, F41, or 987P adhesins (strains 2134 and 2171). Strains 2134 and 2171 were isolated from pigs that had diarrhea after weaning attributable to enterotoxigenic E coli infection. We found that both strains of E coli adhered in the ileum and caused diarrhea in pigs of both age groups. In control experiments, adherent bacteria were not seen in the ileum of pigs < 1 day old or 3 weeks old that were noninoculated or inoculated with a nonpathogenic strain of E coli. These control pigs did not develop diarrhea. Antisera raised against strains 2134 and 2171 and absorbed with the autologous strain, grown at 18 C, were used for bacterial-agglutination and colony-immunoblot assays. Both absorbed antisera reacted with strains 2134 and 2171, but not with strains that express K99, F41, or 987P adhesins. A cross-reaction was observed with 2 wild-type K88 strains, but not with a K12 strain that expresses K88 pili. Indirect immunofluorescence with these absorbed antisera revealed adherent bacteria in frozen sections of ileum from pigs infected with either strain. We concluded that these strains are pathogenic and express a common surface antigen that may be a novel adhesin in E coli strains that cause diarrhea in weaned pigs.

Small intestinal explants from weaned pigs were cultured under a variety of conditions. Explants maintained villus-to-crypt ratio between 1:1 and 1.5:1 for 48 hours. The mucosal epithelium remained well preserved and retained good cellular morphologic features, as determined by light and electron microscopy. Between 48 and 72 hours, considerable mucosal degeneration was evident. Best results were obtained when the explants were cultured on a rocking platform placed in an atmosphere of 95% O2 and 5% CO2, using supplemented RPMI 1640 cell culture medium.

Experiments were conducted to evaluate the effect of restricted feeding of a starter diet to suckling pigs (creep feeding) in a model of postweaning colibacillosis. The hypothesis that restricted creep feeding primes an intestinal allergic reaction to starter diet ingested after weaning was tested. Twenty-eight suckling pigs were fed a starter diet for 3 h/d on days 7, 8, and 9 after birth (creep-fed). Twenty-six suckling pigs were not fed the diet until 3 weeks of age (not creep-fed), when all pigs were weaned and given the starter diet. One day after weaning, 24 creep-fed and 22 not creep-fed pigs were inoculated with K88+ enterotoxigenic Escherichia coli, and 4 pigs in each group were kept as noninoculated controls. Among inoculated pigs (principals), 10 creep-fed and 12 not creep-fed pigs were found to be genetically resistant to K88+ E coli and remained healthy during the 6-day postinoculation period, as did the noninoculated controls. Eighteen (10 creep-fed and 8 not creep-fed) of the 24 genetically susceptible principals developed diarrhea after inoculation. There were no significant differences in the incidence and severity of diarrhea, amount of body weight loss, and mortality between creep-fed and not creep-fed susceptible principal pigs. Histologic examination of intestine from control pigs and principals that survived for 6 days after infection did not reveal any substantial morphologic difference between creep-fed and not creep-fed groups. In conclusion, creep feeding was not required for the production of diarrhea in this model. Creep feeding did not induce morphologic changes characteristic of an allergic reaction in the small intestine.

Sarcoptes scabiei var. suis, ivermectin, single treatment of infected sows before farrowing eliminated scabies from sows and prevented its transmission to their offspring, offspring remained uninfected throughout study regardless of whether they were treated with ivermectin at weaning, infection (epizootic) in growing pigs could be controlled by single treatment of all in-contact pigs but routine treatment of all pigs at weaning does not seem justified