A clinical field trial to evaluate the efficacy of vaccination in controlling Salmonella infection and the association of Salmonella-shedding and weight gain in pigs

Posted in: Ontario Pork, Pork Insight Articles, Welfare by admin on November 23, 2009 | No Comments

A clinical field trial was performed to determine the effectiveness of an autogenous Salmonella Typhimurium bacterin compared with a commercial live S. Choleraesuis vaccine in pigs. The association between Salmonella shedding and weight gain was also investigated. Nine cohorts of weaned pigs, (330 to 350 pigs per cohort), were randomly assigned to 1 of 3 treatment groups (injection with S. Typhimurium bacterin, vaccination via water with S. Choleraesuis vaccine, or a control group receiving no vaccine). In each cohort, the average daily gain was calculated for a selected pen throughout the production stage. Pen (pooled) fecal samples were collected bi-weekly and cultured. The odds of Salmonella shedding in both vaccinated groups was higher than in the control group (P , 0.05). The prevalence of Salmonella shedding declined overall as pigs aged (P 5 0.04). However, the control pigs showed the smallest decrease in Salmonella shedding over the entire production stage, while prevalence of Salmonella shedding in the vaccinated groups decreased twice as much as the control group over the entire production stage. Salmonella Typhimurium var. Copenhagen DT104, S. Cerro, and S. Agona, which had been isolated on the study farm previously, were recovered from pigs in this study. Shedding of S. Typhimurium var. Copenhagen decreased over time in both vaccine treatment groups. On the other hand, S. Cerro shedding rate was lower in the control pigs compared with vaccinated pigs and S. Agona could be recovered only from the samples collected from S. Choleraesuis vaccinated pigs. The pigs from pens with a higher Salmonella recovery rate experienced slower growth compared with pigs from pens where Salmonella was not isolated. This latter finding indicates that there might be an economic incentive for producers to try to control endemic salmonellosis if effective programs could be developed.

Prevalence of Yersinia enterocolitica shedding and bioserotype distribution in Ontario finisher pig herds in 2001, 2002, and 2004

Posted in: Environment, Ontario Pork, Pork Insight Articles, Welfare by admin on October 10, 2009 | No Comments

We investigated characteristics of Yersinia enterocolitica infection in Ontario finisher pig herds. Our specific objectives were to estimate or test: prevalence of Y. enterocolitica shedding in finisher pigs, bioserotype distribution, agreement between the herd-level tests based on sampling pig and pooled fecal samples, whether bioserotypes cluster by farms, and whether Y. enterocolitica-positive herds cluster spatially. In total, 3747 fecal samples were collected from 100 farms over the years 2001, 2002, and 2004 (250 total herd visits). Fecal samples were tested by culture and positive isolates were biotyped and serotyped. Apparent pig-level prevalence of Y. enterocolitica was 1.8%, 3.2%, and 12.5% in 2001, 2002, and 2004, respectively. Estimated true pig-level prevalence of Y. enterocolitica was 5.1%, 9.1%, and 35.1% in 2001, 2002, and 2004, respectively. Herd-level prevalence was 16.3%, 17.9%, and 37.5% in 2001, 2002, and 2004, respectively. In all years, the most common bioserotype was 4, O:3, followed by bioserotype 2, O:5,27. Kappa between herdlevel status based on pig and pooled samples ranged between 0.51 and 0.68 for biotype 1A and bioserotype 4, O:3, respectively. For 4, O:3, a significant bias in discordant pairs was detected, indicating that pig samples were more sensitive than pooled samples in declaring a herd as positive. Farms tended to be repeatedly positive with the same bioserotype, but positive study farms did not cluster spatially (suggesting lack of between herd transmission and lack of a common geographic risk factor).

Domestic pigs alter their social strategy in response to social group size

Posted in: Welfare by admin on October 2, 2009 | No Comments

In a series of studies, we investigated the concept that domesticated pigs may adopt cost efficient social strategies, in which individuals become less aggressive due to a higher number of potential competitors, in large social groups. Six blocks, each comprising four pens of 18 pigs (small group, SG) and two pens of 108 pigs (large group, LG)were used. Pigs were 11 weeks old at the initial group formation. Weeks 1, 6 and 12 following SG and LG formation, two randomly selected pigs with SG or LG social experience were incorporated into another SG or LG for a period of 2 h and the aggressive behaviour of pigs was observed. Four test combinations were used (SG to SG (SS), SG to LG (SL), LG to SG (LS) and LG to LG (LL)). There was less aggression in the LL compared to SS, SL and LS combinations (1.6% versus 2.5, 2.3, and 2.5% of time, respectively, P = 0.009). Furthermore, 8 weeks following

SG and LG formation, a total of 200 pigs were regrouped for 2 h in groups of four in a neutral test arena to assess the effect of prior social experience (SG vs. LG) on aggressive behaviour. Pigs were regrouped with their own group members (familiar), or with unfamiliar non-group members either from SG or LG. Five test combinations were used (four pigs from the same SG (S), four pigs from the same LG (L), two pigs from a SG and two pigs from a LG (SL), two pigs each from two different LG (LL) and two pigs each from two different SG (SS)). Pigs derived from SG fought aggressively (duration, s) with unfamiliar pigs, compared to those derived from LG (4.9, 6.7, 16.1, 12.1 and 9.5 s for S, L, SS, SL and LL test combinations respectively, P < 0.001). In addition, the latency to initiate first aggressive interaction was shorter (duration, s) in SS than LL treatment combination (23.3, 22.5, 10.8, 11.8 and 19.2 s for S, L, SS, SL and LL test combinations respectively, P = 0.008). Taken together, our results suggest that pigs become less aggressive and may shift to a low-aggressive social strategy in large social groups. This may provide potential benefits for welfare of pigs under commercial production situations.

Characterization of triple reassortant H1N1 influenza A viruses from swine in Ohio

Posted in: Welfare by admin on July 30, 2009 | No Comments

An H1N1 influenza A virus, A/swine/Ohio/24366/07, was isolated from pigs in an Ohio county fair. Twenty-six people who came in contact with the infected pigs develop respiratory disease and two of these people were laboratory confirmed as H1N1 by the Centers for Disease Control and Prevention (CDC). The A/swine/Ohio/24366/07 virus we isolated from swine was shown at the CDC to have 100% identical genome sequence to the human virus associated with the county fair. This prompted us to characterize three swine and two human origin H1N1 influenza A viruses isolated at different time points in the State of Ohio. The three swine viruses were shown to be triple reassortant viruses harboring genes of human (PB1), swine (HA, NA, NP, M, and NS), and avian (PB2 and PA) lineage viruses. Although viruses evaluated in this study were isolated during a short time interval (3 years), genetic drift was observed within the HA and NA genes, including changes at the receptor binding and antigenic sites of HA1 protein. Nevertheless, all viruses exhibited antigenic similarity as evaluated with hemagglutination inhibition and virus neutralizing tests. Internal genes were similar to other reassortant viruses of various subtypes currently circulating in the United States. Interestingly, two of the swine viruses including the 2007 isolate replicated well in human airway epithelial cells, however, another virus isolated in 2006 showed very little replication.

For more information the full article can be found at http://www.sciencedirect.com/science/journal/03781135

Alternative Value Chains: Jones Feed Mills Case Study

Posted in: Pork Insight Articles, Production, Welfare by admin on April 1, 2009 | No Comments

In the Breton Family development of niche market products, Jones Feed Mills partnered with the duBreton for a 3 site production that is Certified Humane®. The Certified Humane® program feeds wholesome, nutritious feed with no mammalian protein, antibiotics, or growth promoters, and feeders must allow easy access to feed. Average weaning age must by 28 days or more, and creep feed needs to be supplied from day 10 on. Water must be clean and accessible, building specifications need to be recorded, and a comfortable lying space must be provided. Specific space allowances need to be followed, pigs must have freedom of movement, and confinement is only allowed under certain circumstances. Traditional farrowing crates are not allowed, sows must be given nesting material, and sows must be kept in the farrowing area for 28 days after farrowing. Environmental enrichment must be given, isolation is only allowed for quarantine/treatment, and abnormal behaviours (ex. tail biting) should be documented and steps taken to eliminate the behaviour. Finally, units must have an Animal Health Plan, sick animals need to be treated, and the only physical alterations allowed are needle teeth clipping, castration before 7 days, and boar tusk trimming. Ear notching and routine tail docking are not allowed.

Aggression in replacement grower and finisher gilts fed a short-term high-tryptophan diet and the effect of long-term human–animal interaction

Posted in: Pork Insight Articles, Welfare by admin on January 16, 2009 | No Comments

Aggression can be a major problem for swine production as it negatively impacts the pigs’ health and welfare. Increasing tryptophan (TRP) intake to raise brain serotonin (5-HT)—key for aggression control, and long-term positive social handling can reduce stress in pigs. Objective was to feed a short-term high-TRP diet to grower (3 months) and finisher (6 months) maternal gilts that were either socially handled or not and measure their behavioural activity and aggressiveness. Eight pens of six unrelated gilts were split into two blocks balanced for litter, social handling (non- vs. handled) and dietary treatment (control vs. high-TRP). Social-handling was applied three times per week, from day 45 until 6 months of age. At 3 months, two handled and two non-handled pens were assigned to control while the other four pens were assigned to the high-TRP diet fed ad libitum for 7 days (days 1–7). At 6 months of age, pen assignment to dietary treatments was swapped. Body weights and blood were taken at days 1 (pre-feeding) and 7. Blood samples were analyzed for TRP and 5-HT concentrations using high pressure liquid chromatography. Behaviour was recorded from days 1 to 5 and scan-sampling used to determine time-budget behaviours and postures in a 12-h period each day (06:00–18:00 h). Aggression evaluation in the home pen focused on counts of agonistic interactions, bites and head-knocks per interaction during three, 30-min intervals (08:00, 12:00, and 16:00 h) from days 1 to 5. Resident–intruder (R–I) test was carried out for a maximum of 300 s at days 6 and 7 to measure aggressiveness, predicted by the latency to the first attack and attack outcomes. A 2 × 2 factorial arrangement of dietary treatment and social handling within age was analyzed by repeated measures of mixed models and Tukey adjustments. The TRP-added diet raised blood TRP concentration of 3- and 6-month-old gilts by 180.7% and 85.2% respectively (P < 0.05), reduced behavioural activity and time spent standing, while increasing lying behaviour, mostly in grower gilts (P < 0.05). High-TRP diet reduced the number of agonistic interactions, and aggressiveness in 3-month-old gilts, which took longer to attack the intruder pig, and displayed fewer attacks on the first day of testing (P < 0.05). Long-term positive social handling improved growth performance and had a slight effect on behaviour (P < 0.05). Provision of enhanced TRP diet reduced behavioural activity and aggressiveness of grower gilts, and these results are likely mediated by activation of brain serotonergic system. Short-term high-TRP dietary supplementation may be used to reduce aggression at mixing in young pigs.

For more information the full article can be found at http://journals.elsevierhealth.com/periodicals/applan/issues

Porcine circovirus type 2 in muscle and bone marrow is infectious and transmissible to naïve pigs by oral consumption

Posted in: Welfare by admin on January 1, 2009 | No Comments

The objectives of this study were to determine if pork products from PCV2-infected pigs contain PCV2 DNA/antigen and to determine if the PCV2 present in the tissues is infectious by performing in vitro and in vivo studies. Results from this study indicate that uncooked PCV2 DNA positive lymphoid tissues, bone marrow, and skeletal muscle from PCV2 viremic pigs contain sufficient amount of infectious PCV2 to infect naïve pigs by the oral route.

For more information the full article can be found at http://www.sciencedirect.com/science/journal/03781135

Reliability of temperament tests on finishing pigs in group-housing and comparison to social tests

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This study focused on temperament tests in group-housed finishing pigs, with the objective of validating measures that are readily applicable in commercial settings and potentially related to individual differences in stress response. At 24 weeks of age, animals were subjected to three tests of fear in the home pen: the human approach test (HAT), novel object test (NOT) and open door test(ODT). It was found that latency to perform all three fear tests decreased significantly over time. Comparisons between group fear tests and social tests showed that pigs which readily approach a human tended to have higher lesion scores and fewer feeding bouts in the feed competition trial. While test latencies decrease with repetition, the HAT and ODT show individual consistency over time, which suggests that these tests describe behavioural tendencies and may be useful for predicting fearful responses at slaughter.

For the full text please subscribe to the Journal of Applied Animal Behaviour Science

Epidemiological Evaluation of Pain in Swine Herds

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Pain is an important cause for compromised welfare in swine herds. However,painful processing procedures have  become part of routine farm management, and this incongruity has been the focus of many nonhuman animal welfare
arguments. Processing procedures are 1-time events compared with the ever present susceptibility to painful diseases. Despite the widespread impacts, pain associated with diseases (lameness, Mastitis-Metritus-Agalactia Syndrome, pleuritis, and the like) is seldom addressed in animal welfare discussion; the focus, when discussed, often is on the painful processing procedures. Pain persists for longer than the clinical signs, may remain invisible, and may lead to hyperalgesia. The problem with diseases as a threat to welfare is that despite a herd-level prevalence, often diseases are dealt with on an individual basis. In reality, it may have higher impacts on herd-level welfare than usually ascribed, and providing evidence to this situation is an epidemiological challenge. Translating individual level assessments for herd-level relevance needs consideration of severity, duration, and prevalence. Often, only the severity of the disease at the individual level alone is assessed—which is clearly insufficient. A low-intensity pain but for a long duration may be of different significance to an individual animal within a herd

Societal concern related to stocking density, pen size and group size in farm animal production

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In this study available survey data from Flemish citizens, collected by the researchers during the period 2000–2006, in different waves and with different purposes, are explored in order to gain insights in the societal concern and perception of space allowance as an animal welfare issue. It was found that found that the societal concern of both stocking density and pen size is imperative within the full picture of farm animal welfare. In comparison with other animal welfare related aspects, both stocking density and pen size rank high in terms of perceived importance and receive relatively low evaluative belief scores. The perceived importance for group size is considerably lower as compared to stocking density and pen size, and citizen judgments are milder towards this aspect.

For more information the full article can be found at http://www.journals.elsevierhealth.com/periodicals/livsci