Objective—To determine the effect of split nursing
(ie, removal of the larger pigs in a litter from the dam
for a short period within 24 hours after birth to allow
the smaller pigs in the litter uninhibited access to the
dam) on variation in growth from birth to weaning
Animals—1,193 pigs in 118 litters.
Procedure—Litters were randomly assigned to 1 of 3
treatment groups: control group (pigs were not split
nursed), group 1 (heaviest 50% of pigs in the litter
were removed from the sow for 2 hours), or group 2
(heaviest 50% of pigs were removed from the sow
for 2 hours and, after the heaviest pigs were returned
to the sow, the lightest 50% of pigs were removed
for 2 hours). Birth weights and weaning weights were
Results—Significant differences in average daily gain
(ADG), weaning weight, or serum IgG concentration
among groups were not detected. However, significant
linear improvements in the SD and coefficient of
variation of the ADG were detected, but only for litters
with ≥ 9 pigs born alive. Percentages of pigs from
split-nursed litters that weighed < 3.6 kg (8 lb) at
weaning (1.3 and 1.6% for groups 1 and 2, respectively)
were lower than percentage of control pigs that
Conclusion and Clinical Relevance—Results suggest
that split nursing will decrease variation in ADG
of pigs from birth to weaning but only for pigs from litters
with ≥ 9 pigs born alive. (J Am Vet Med Assoc
Objective—To evaluate effect of various regimens
for administration of antimicrobials in feed on growth
rate and feed efficiency (feed/gain) of pigs in multisite
Animals—24,099 growing pigs in 3 multisite production
Procedure—10 trials involving various regimens for
administration of antimicrobials in feed were evaluated.
Trial 1 compared effects of 2 antimicrobial regimens
on finishing pig performance. Trials 2 through
10 compared growth rate and feed efficiency of nursery
and finishing pigs given antimicrobials in feed
with values for control pigs not given antimicrobials.
Results—In trial 1, no significant differences were
observed between the 2 antimicrobial regimens. In
the remaining trials, growth rate of nursery pigs fed
antimicrobials was significantly improved, compared
with growth rate of control pigs. However, growth
rate of finishing pigs and feed efficiency of nursery
and finishing pigs were not significantly improved by
adding antimicrobials to the feed.
Conclusions and Clinical Relevance—Results suggest
that use of antimicrobials in the feed to promote
growth should be limited to the nursery phase in multisite
pig production systems. Use of antimicrobials in
the feed of finishing pigs should be limited to therapeutic
applications in which a diagnosis of bacterial
infection susceptible to the antimicrobial to be used
has been confirmed. (J Am Vet Med Assoc
Objective—To determine the pharmacokinetic parameters of xylazine, ketamine, and butorphanol (XKB) administered IM and sodium salicylate (SAL) administered PO to calves and to compare drug effects on biomarkers of pain and distress following sham and actual castration and dehorning.
Animals—40 Holstein bull calves from 3 farms.
Procedures—Calves weighing 108 to 235 kg (n = 10 calves/group) received one of the following treatments prior to sham (period 1) and actual (period 2) castration and dehorning: saline (0.9% NaCl) solution IM (placebo); SAL administered PO through drinking water at concentrations from 2.5 to 5 mg/mL from 24 hours prior to period 1 to 48 hours after period 2; butorphanol (0.025 mg/kg), xylazine (0.05 mg/kg), and ketamine (0.1 mg/kg) coadministered IM immediately prior to both periods; and a combination of SAL and XKB (SAL+XKB). Plasma drug concentrations, average daily gain (ADG), chute exit velocity, serum cortisol concentrations, and electrodermal activity were evaluated.
Results—ADG (days 0 to 13) was significantly greater in the SAL and SAL+XKB groups than in the other 2 groups. Calves receiving XKB had reduced chute exit velocity in both periods. Serum cortisol concentrations increased in all groups from period 1 to period 2. However, XKB attenuated the cortisol response for the first hour after castration and dehorning and oral SAL administration reduced the response from 1 to 6 hours. Administration of XKB decreased electrodermal activity scores in both periods.
Conclusions and Clinical Relevance—SAL administered PO through drinking water decreased cortisol concentrations and reduced the decrease in ADG associated with castration and dehorning in calves.
Objective—To determine the relationship between
ambient temperature and mean body surface temperature
(MBST) measured by use of infrared thermography
(IRT) and to evaluate the ability of IRT to
detect febrile responses in pigs following inoculation
with Actinobacillus pleuropneumoniae.
Animals—28 crossbred barrows.
Procedures—Pigs (n = 4) were subjected to ambient
temperatures ranging from 10 to 32 C in an environmental
chamber. Infrared thermographs were
obtained, and regression analysis was used to determine
the relationship between ambient temperature
and MBST. The remaining pigs were assigned to
groups in an unbalanced randomized complete block
design (6 A pleuropneumoniae-inoculated febrile pigs
[increase in rectal temperature ≥ 1.67 C], 6 A pleuropneumoniae-inoculated nonfebrile pigs [increase in rectal
temperature < 1.67 C], and 12 noninoculated pigs).
Infrared thermographs and rectal temperatures were
obtained for the period from 2 hours before to 18
hours after inoculation, and results were analyzed by
use of repeated-measures ANOVA.
Results—A significant linear relationship was
observed between ambient temperature and MBST
(slope, 0.40 C). For inoculated febrile pigs, a treatment
X method interaction was evident for rectal temperature
and MBST, whereas inoculated nonfebrile pigs
only had increased rectal temperatures, compared
with noninoculated pigs. A method X time interaction
resulted from the longer interval after inoculation until
detection of an increase in MBST by use of IRT.
Conclusions and Clinical Relevance—Infrared thermography
can be adjusted to account for ambient
temperature and used to detect changes in MBST
and radiant heat production attributable to a febrile
response in pigs. (Am J Vet Res 2001;62:676–681)
Procedures—Pigs (10 pigs/treatment) were fed a corn–soybean meal basal (control) diet or the basal diet supplemented with additional minerals (copper and manganese or silicon), amino acids (proline and glycine; a combination of leucine, isoleucine, and valine; or methionine and threonine), or fatty acids (provided by fish oil) for 84 days. Pigs were then slaughtered and the distal portion of the left femur was collected for determination of osteochondrosis lesions at the femoral condyle. After evaluation of external joint surfaces, the distal portion of the femur was sectioned to evaluate lesions in the growth plate and articular cartilage. Additionally, a cartilage specimen was obtained from the patella for analysis.
Results—Pigs fed diets containing high amounts of methionine and threonine or the diet containing all additional ingredients had significantly lower total severity scores, compared with scores for pigs fed the control diet or a diet supplemented with fish oil. Pigs fed diets containing additional proline and glycine, copper and manganese, methionine and threonine, or all additional ingredients had significantly lower overall scores, compared with scores for pigs fed the control diet or a diet supplemented with fish oil.
Conclusions and Clinical Relevance—Dietary manipulation decreased the severity of osteochondrosis lesions, compared with results for pigs fed a control diet. However, additional research on optimal concentrations and combinations of dietary components is needed.
Objective—To evaluate the use of serum biomarkers of cartilage and bone metabolism to predict the occurrence and severity of osteochondrosis (OC) lesions in the distal portion of the femur in growing swine.
Procedures—At an abattoir, serum samples for analysis of 10 biomarkers indicative of cartilage and bone metabolism were obtained prior to processing of the pigs. The distal portion of each pig's left femur was directly examined and cut into longitudinal sections to evaluate the number and severity of abnormalities on the external surface, articular cartilage, and growth plate. Each specimen was categorized as with (n = 56) or without (15) OC, and an overall OC severity score was assigned to affected pigs. Logistic and linear regression analyses were performed to predict odds of OC on the basis of biomarker concentrations and predict the severity of OC values in affected pigs, respectively.
Results—Compared with values in unaffected pigs, serum concentrations of C-propeptide of type II collagen (CPII) and cartilage oligomeric matrix protein were significantly increased and concentrations of carboxy-terminal telopeptide of type II collagen 3/4-length fragment (C2C) and pyridinoline cross-links were significantly decreased in affected pigs. A 2-fold increase in CPII concentration increased the odds of pigs having OC by a factor of 97 (95% confidence interval, 6 to infinity). Changes in serum C2C concentration accounted for 49% of the variation in overall OC severity score.
Conclusions and Clinical Relevance—Assessment of serum biomarker concentrations may be useful in the diagnosis of OC and aid in reduction of lameness in swine herds.
Objective—To evaluate, under field conditions, the effects of a commercial porcine circovirus type 2 (PCV2) vaccine on mortality rate and growth performance in a herd infected with PCV2 that had a history of porcine circovirus disease.
Design—Randomized controlled clinical trial.
Animals—485 commercial, cross-bred, growing pigs.
Procedures—Prior to weaning, pigs were randomly assigned within litter to a vaccination or unvaccinated control group. Pigs in the vaccination group were given a commercial PCV2 vaccine at weaning and 3 weeks later. Mortality rate was recorded, and pigs were weighed prior to vaccination, when moved from the nursery, and prior to marketing. Infection status was assessed by serologic testing and detection of viral DNA in serum.
Results—Compared with control pigs, pigs vaccinated against PCV2 had a significantly lower mortality rate during the finishing phase, significantly higher average daily gain during the finishing phase, and significantly lower likelihood of being lightweight at the time of marketing. For vaccinated pigs, overall mortality rate was reduced by 50% and average daily gain during the finishing period was increased by 9.3%. At the time of marketing, vaccinated pigs weighed an average of 8.8 kg (19.4 lb) more than control pigs, without any difference in days to marketing. Serum PCV2 antibody titers increased in control pigs, and PCV2 DNA was detected, indicating active PCV2 infection.
Conclusions and Clinical Relevance—Results suggested that vaccination against PCV2 was effective at reducing mortality rate and improving growth performance among pigs in a herd infected with PCV2.
OBJECTIVE To determine the minimum infectious dose of porcine epidemic diarrhea virus (PEDV) in virus-inoculated feed.
ANIMALS 30 crossbred 10-day-old pigs.
PROCEDURES Tissue culture PEDV was diluted to form 8 serial 10-fold dilutions. An aliquot of stock virus (5.6 × 105 TCID50/mL) and each serial PEDV dilution were mixed into 4.5-kg batches of feed to create 9 PEDV-inoculated feed doses; 1 virus-negative dose of culture medium in feed was also created. Pigs were challenge exposed via oral administration of PEDV-inoculated feed, and fecal swab specimens were collected. All pigs were euthanized 7 days after challenge exposure; fresh tissues were collected and used for PCR assay, histologic examination, and immunohistochemical analysis.
RESULTS The PCR cycle threshold (Ct) decreased by approximately 10 when PEDV was added to feed, compared with results for equivalent PEDV diluted in tissue culture medium. Pigs became infected with PEDV when challenge exposed with the 4 highest concentrations (lowest concentration to cause infection, 5.6 × 101 TCID50/g; Ct = 27 in tissue culture medium and 37 in feed).
CONCLUSIONS AND CLINICAL RELEVANCE In this study, PEDV in feed with detectable Ct values of 27 to 37 was infective. The Ct was 37 for the lowest infective PEDV dose in feed, which may be above the limit of detection established for PEDV PCR assays used by some diagnostic laboratories. Overall, results indicated 5.6 × 101 TCID50/g was the minimum PEDV dose in feed that can lead to infection in 10-day-old pigs under the conditions of this study.