Field evaluation of a ready-to-use combined Porcine circovirus type 2 and Mycoplasma hyopneumoniae vaccine in Denmark - a historical comparison of productivity parameters in 20 nursery and 23 finishing herds.

BACKGROUND: In practice, field evaluation of vaccine efficacy in individual herds is often based on a historical comparison of productivity data following initiation of vaccination. Being biased by time, this study design highly contrasts the more controlled, parallel-group design used for most initial vaccine efficacy studies but offers the possibility of including a larger number of animals and herds. As an important add-on to previous findings in controlled studies, the objective of this study was to evaluate the field efficacy of the ready-to-use combination vaccine Porcilis® PCV M Hyo (MSD Animal Health) by an observational historical study design using routinely generated herd productivity data. RESULTS: Data on mortality, average daily weight gain and feed conversion rate were collected as yearly averages for one year prior to and one year after implementation of Porcilis® PCV M Hyo vaccination from 20 nursery and 23 finishing herds. When comparing pre- and post-vaccination periods, the average improvements in productivity data amounted to - 0.4 percentage points for mortality (p = 0.014), + 5 g for average daily weight gain (p = 0.555) and - 0.06 feeding units(FU)/kg for feed conversion rate (p = 0.074) in nursery herds and - 0.5 percentage points for mortality (p = 0.012), + 34 g for average daily weight gain (p < 0.001) and - 0.04 FU/kg for feed conversion rate (p = 0.133) in finishing herds. Even though some nursery and finishing herds also previously vaccinated against PCV2 and/or Mycoplasma hyopneumoniae, this did not significantly affect the results. For finishers, these results were obtained when difference in arrival weights between the periods and shared ownership of the herds were additionally taken into account. CONCLUSION: In these 20 nursery and 23 finishing herds, previous findings from parallel-group vaccination studies concerning average daily weight gain for finishers were confirmed. Additionally, a significant effect on mortality for both nursery and finishing herds was demonstrated in this evaluation based on routinely generated herd productivity data.

Comparison of serum pools and oral fluid samples for detection of porcine circovirus type 2 by quantitative real-time PCR in finisher pigs.

BACKGROUND: Porcine circovirus type 2 (PCV2) diagnostics in live pigs often involves pooled serum and/or oral fluid samples for group-level determination of viral load by quantitative real-time polymerase chain reaction (qPCR). The purpose of the study was to compare the PCV2 viral load determined by qPCR of paired samples at the pen level of pools of sera (SP) from 4 to 5 pigs and the collective oral fluid (OF) from around 30 pigs corresponding to one rope put in the same pen. Pigs in pens of 2 finishing herds were sampled by cross-sectional (Herd 1) and cross-sectional with follow-up (Herd 2) study designs. In Herd 1, 50 sample pairs consisting of SP from 4 to 5 pigs and OF from around 23 pigs were collected. In Herd 2, 65 sample pairs consisting of 4 (SP) and around 30 (OF) pigs were collected 4 times at 3-week intervals. RESULTS: A higher proportion of PCV2-positive pens (86% vs. 80% and 100% vs. 91%) and higher viral loads (mean difference: 2.10 and 1.83 log(10) PCV2 copies per ml) were found in OF versus SP in both herds. The OF cut-off value corresponding to a positive SP (>3 log(10) PCV2 copies per ml) was estimated to 6.5 and 7.36 log(10) PCV2 copies per ml for Herds 1 and 2, respectively. Significant correlations between SP and OF results were found in Herd 1 (rho = 0.69) and the first sampling in Herd 2 (rho = 0.39), but not for the subsequent consecutive 3 samplings in Herd 2. CONCLUSIONS: The proportion and viral loads of PCV2 positive pens were higher in collective OF (including up to 30 pigs) compared to SP (including 4-5 pigs) of the same pens. Also, OF seemed to detect the PCV2 infection earlier with OF values just below 6.5 (Herd 1) and 7.36 (Herd 2) log(10) being associated with a negative SP for the same pen. Nevertheless, a statistically significant correlation between SP and OF could not be found for all sampling time points, probably due to a high within-pen variation in individual pig viral load becoming very evident in SP of only four or five pigs. Consequently, the results imply that OF is well suited for detecting presence of PCV2 but less so for determining the specific viral load of pigs in a pen.

Effect of vaccination against sub-clinical Porcine Circovirus type 2 infection in a high-health finishing pig herd: A randomised clinical field trial.

During the last decade, the clinical manifestation of Porcine Circovirus type 2 (PCV2) infections has mostly changed from postweaning multisystemic wasting syndrome and high mortality to sub-clinical infections manifested only through impaired production parameters. However, co-infection with other respiratory pathogens often results in a larger effect on production, sometimes with clinical signs. Little is known about the impact of a moderate level PCV2 infection without co-infections, particularly in terms of feed conversion ratio and antimicrobial consumption. The purpose of the study was to evaluate the effect of vaccination against PCV2 in a sub-clinically infected, high-health finishing herd in terms of viral load in serum, feed conversion ratio and antimicrobial treatments. The study was conducted as a randomised clinical field trial with a parallel group design. Vaccination against PCV2 significantly (p<0.001) reduced the prevalence of PCV2-positive serum pools, from 91% in the control group to 6% in the vaccinated group, as well as the viral load for positive pools from 5.79 to 3.99 log(10) copies per ml serum. Despite this, feed conversion ratio for the two groups were not significantly different with an average of 2.75 and 2.76 feeding units/kg gain for vaccinated and control pigs, respectively (p=0.598). The proportion of pigs treated by injection with an antimicrobial was lower in the vaccinated group (4.4%) compared to the non-vaccinated group (5.6%), but the difference was not significant (p=0.125). In conclusion, in this herd without respiratory co-infections and with moderate viral loads of PCV2, vaccination significantly reduced the prevalence and viral load of PCV2-positive pigs, but had no significant impact on feed conversion ratio or antimicrobial consumption.

Comparison of recording of pericarditis and lung disorders at routine meat inspection with findings at systematic health monitoring in Danish finisher pigs.

BACKGROUND: The use of secondary data is widespread in a range of surveillance and monitoring applications because of the low cost and high availability associated with this form of data. However, as they are often collected for quite unrelated purposes, they are not necessarily fit for the new purpose that is required of them. Routine meat inspection data were originally collected with the purpose of safeguarding food, but have been re-tasked to also include animal welfare assessment. The objective of the present study was to compare the recording of pericarditis, pleuritis and lungs with lesions at routine meat inspection (RMI) with those performed at systematic health monitoring (SHM) in Danish pigs at slaughter, in order to assess the usefulness of RMI for monitoring the prevalence of these diseases. Data originating from 165 Danish pig herds were collected in the period September 2011 to November 2013. From each herd, a batch consisting of all pigs slaughtered on a specific day from a specific farm were included as the RMI data, while lungs and hearts sampled from the batches were used for the SHM. The RMI data and SHM data included recordings related to a) chronic pericarditis, b) chronic pleuritis and c) lung lesions. The proportion of carcases with a specific disease recording was estimated for each batch of pigs, and linear regression was used to relate the RMI-proportion to the SHM-proportion for the conditions mentioned above. RESULTS: The coefficients of determination (R(2)) were estimated as R(2),pericarditis = 0.16; R(2),pleuritis = 0.67; R(2),lungs with lesions = 0.40. R(2),pericarditis changed to 0.42 when the regression analysis included inspection type at the abattoir (with purely visual inspection of the hearts versus traditional inspection including an incision into the heart). CONCLUSIONS: Overall, the results suggest that the correlation between findings at RMI and SHM was moderate for pleuritis and lungs with lesions, but poor for pericarditis. The latter could partly be explained by the type of meat inspection conducted at the abattoir. We conclude that caution should be used whenever RMI data are used for purposes other than those for which they were originally intended.

Prevalence of nematodes in Danish industrialized sow farms with loose housed sows in dynamic groups.

The aim of this study was to investigate the prevalence of nematodes in sows and gilts in modern pig herds which practiced loose housing of sows and gilts. Seventy hundred and ninety fecal samples were examined from seventy-nine farms. Oesophagostomum spp. was found in 15% of farms and Ascaris suum was found in 76% of the farms. Trichuris suis was found in a very few instances. No other nematodes were found. The prevalence of Oesophagostomum spp. within an infected farm was approximately 50% and the prevalence of Ascaris suis within an infected farm was approximately 30%. Housing procedure, farm size and the degree of contact with feces could not be correlated to prevalence on a farm level. It was concluded that in modern sow farms with loose housing systems A. suum and Oesophagostomum spp. are sufficiently prevalent to be considered a threat to productivity.