Survival of classical swine fever virus at various temperatures in faeces and urine derived from experimentally infected pigs

Posted in: Welfare by admin on January 1, 2008 | No Comments

Indirect transmission of classical swine fever virus (CSFV) can occur through contact with mechanical vectors, like clothing and footwear or transport vehicles, contaminated with the secretions or excretions of infected pigs. A prerequisite for indirect transmission is survival of the virus on the mechanical vector. Consequently, to obtain more insight into these transmission routes, it is important to know how long the virus remains viable outside the host. In this study we examined the survival of classical swine fever virus in faeces and urine derived from pigs intranasally inoculated with a highly or moderately virulent CSFV strain. Faeces and urine were collected between days 5 and 36 post-inoculation, and stored at 5, 12, 20, and 30 8C. Next, the virus titres were determined in the samples by virus titration, and a random selection of these samples was also analyzed by quantitative real-time reverse transcription polymerase chain reaction (qRRT-PCR) to determine the viral RNA decay. Survival curves were generated, and it was shown that the inactivation rate was inversely related to the storage temperature. Average halflife values were between 2 and 4 days at 5 8C, and between 1 and 3 h at 30 8C. Significant differences were observed in survival between virus strains in faeces, however, not in urine. The reduction in viral RNA during the entire study period was limited. This
study provided detailed information on survival of CSFV in excretions of infected pigs, which can be used to improve control measures or risk-analysis models.

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

Relationship between serum acute phase protein concentrations and lesions in finishing pigs

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To establish the relationship between serum levels of three acute phase proteins, haptoglobin (Hp), C-reactive protein (CRP) and serum amyloid A (SAA), and the occurrence and severity of lesions at slaughter, a study was carried out using 70 fattening pigs from a finishing unit. It was found that serum levels of CRP, SAA and Hp were significantly higher in pigs with clinical signs of disease than in apparently healthy animals. Additionally, in apparently healthy pigs, serum levels of Hp and CRP were significantly higher in animals with lesions than those without lesions. The extent and severity of lung lesions were related to serum levels of Hp.

For more information the full article can be found at  http://www.sciencedirect.com/science/journal/10900233

Effect of out-of-feed events and diet particle size on pig performance and welfare

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There appear to be three major causes for out-of-feed events in grower-finisher facilities. Human errors are generally associated with empty bins. This occurs when feed is not ordered, prepared, or delivered in a timely manner. The second cause of out-of-feed events is bridging of ground feed in feed storage devices. In this case, issues associated with flowability prevent feed from flowing out of the storage device into the feed delivery system. The final cause of out-of-feed events is equipment malfunction, this generally increases as facilities age. The consequences to the pig are the same regardless of the cause of an out-of-feed event. Considerable anecdotal evidence suggests that when pigs are given access to feed following a period of deprivation, an increase in fighting and aggressive behaviors occurs, and it is likely that this will adversely affect the welfare of all pigs within that pen. Irregular availability of feed during two daily 2-hour periods has been used as a stressor in a study examining acute-phase protein levels as biomarkers for evaluation of distress in growing pigs. Short-term feed deprivation (24 hours) has been clearly shown to cause ulcers in growing pigs. Periodic feed interruptions would likely create a similar effect in pigs fed ad libitum. While most ulcers had been repaired within 28 days in pigs fed a diet with particle size 750 microns, stomach ulceration continued in pigs either remaining on a finely ground diet (550 microns) or continuing to experience weekly feed deprivations. Interruptions in feeding such as occur with out-of-feed events may be inciting factors for hemorrhagic bowel syndrome. Over-eating, especially after a period of feed deprivation, has been implicated as a cause of porcine intestinal hemorrhage syndrome. The following experiments were designed to examine the impact of repeated out-of-feed events on pig performance, carcass composition, and incidence of tail biting and skin lesions. In each of two experiments, out-of-feed events of 20-hour duration were created by closing the feeder delivery devices from noon until 8:00 am the following morning. In Experiment One, the treatments were never or weekly out-of-feed events for a 16-week period, and 1266-micron versus 1019-micron mash feed-particle size. In Experiment Two, the treatments were zero, one, two, or three out-of-feed events on random days every 2-week period in the 16-week study. In each experiment, there were four pens per treatment combination or treatment and 15 pigs per pen. Weekly events resulted in a 68-g per day lower daily gain for the first 8 weeks, and 35-g per day lower gain over the entire trial, compared to the never out-of-feed treatment, with no impact on feed conversion. Feed conversion was better when feed particle size was 1019 microns versus 1266 microns. In Experiment Two, there was a linear decrease in daily gain with increasing numbers of out-of-feed events during the first 8-week period, with no impact during the second 8-week period. There was no effect of treatments on feed conversion. It was concluded that repeated out-of-feed events had a bigger impact on growing pigs than on finishing pigs, with the impact expressed as lower weight gain with no effect on feed conversion.

For more information the full article can be found at http://www.aasv.org/shap/issues/v16n2/v16n2p72.htm

Molecular detection of norovirus in sheep and pigs in New Zealand farms

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Human norovirus (NoV) is reportedly the major cause of non-bacterial gastroenteritis outbreaks worldwide and is commonly associated with water- and food-borne transmission via the faecal–oral route. Aside from humans, norovirus has been detected in pigs, cattle and mice. The close relatedness of some human and animal noroviruses has raised concerns about potential zoonotic transmission. Our laboratory recently reported the development of a multiplex real-time RT-PCR for the detection and genotyping of norovirus of genogroups I–III.  Here we report a study of 56 faecal specimens from pigs and sheep that were collected and screened for noroviruses using this assay. Norovirus was found in 2/23 (9%) of porcine specimens (all were genogroup II) and in 8/33 (24%) of ovine specimens (all were genogroup III). Samples tested positive for norovirus were verified by conventional RT-PCR with different primer sets. Genomes of representative porcine and ovine norovirus strains underwent partial sequence analysis (343 and 2045 bases, respectively). This is the first report describing norovirus in sheep.

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

Isolated weaning technology: Humane benefits and concerns in the production of pork

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The age at which piglets are separated from the sow has been identified as an animal welfare risk in current swine production systems. Animal welfare gains of a minimal disease state must be objectively balanced against the welfare costs of early weaning. Veterinary practitioners should continue to participate in the development and validation of humane animal production methods.

Effect of dietary soybean oil and soybean protein concentration on the concentration of digestible amino acids in soybean products fed to growing pigs

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The apparent ileal digestibility (AID) of amino acids by growing pigs is increased if oil is added to the diet (Li and Sauer, 1994; Albin et al., 2001). Standardized ileal digestibility values (SID) for crude protein and amino acids take into account the amino acid contributions of endogenous origins, and values for SID are more accurate estimates of the digestibility of amino acids in a feed ingredient compared with values for AID (Stein et al., 2007). However, there is limited information about the effect of dietary oil on the SID of amino acids in soybean products fed to pigs. It has been suggested (NRC, 1998) that the digestibility of amino acids in full-fat soybeans (FFSB) is less than in soybean meal (SBM) and soy protein concentrate (SPC). This is surprising because full-fat soybeans contain more oil than SBM and SPC (Cromwell, 2000; Zarkadas and Wiseman, 2005), and it would, therefore, be expected that the digestibility of amino acids in FFSB is greater than in defatted soybean products. Because increased protein concentration in soybeans is often accompanied by a reduced concentration of oil (Yaklich, 2001), the digestibility of amino acids in high-protein soybean varieties may be different from the digestibility in conventional varieties. The objective of this experiment was to measure the effect of oil addition to SBM and SPC on AID and SID of crude protein and amino acids by growing pigs and to compare these values to the AID and SID for crude protein and amino acids in FFSB. The second objective was to compare the digestibility of amino acids and the concentration of digestible amino acids in a new high-protein variety of FFSB (FFSB-HP) to values obtained in conventional sources of FFSB (FFSB-CV), SBM, and SPC. Four diets were prepared using each soybean product as the sole source of crude protein and amino acids in 1 diet. Two additional diets were formulated by adding soybean oil (7.55 and 7.35%, respectively) to the diets containing SBM and SPC. A nitrogen-free diet was also used to measure basal endogenous losses of crude protein and amino acids. The 2 sources of FFSB were extruded at 150°C before being used in the experiment. Seven growing barrows (initial BW = 26.2 kg) were prepared with a T-cannula in the distal ileum and allotted to a 7 × 7 Latin square design. Ileal digesta were collected from the pigs on day 6 and 7 of each period. All digesta samples were lyophilized and analyzed for DM, crude protein, amino acids, and chromium, and values for AID and SID of crude protein and amino acids were calculated. The addition of oil improved (P < 0.05) the SID of most indispensable amino acids in SBM and SPC. The SID for 6 of the indispensable amino acids in FFSB-HP were greater than in FFSB-CV, and the SID for all indispensable amino acids except Met was greater in FFSB-HP than in SBM. However, the SID for most amino acids in FFSB-HP was similar to SBM with oil and SPC, but these values were lower than in SPC with oil. In conclusion, the addition of oil improved the SID of most amino acids in SBM and SPC fed to growing pigs, and the SID of amino acids in FFSB-HP were greater than in SBM and similar to the SID of amino acids in SBM with oil and in SPC.

For more information the full article can be found at http://jas.fass.org/

Comparing fogging strategies for pig rearing using simulations to determine apparent heat-stress indices

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Strategies to reduce the apparent heat-stress indices inside a growing pig building were compared. Two fogging strategies were studied, fogging with the necessary water evaporating to give the same: (i) duration of heat-stress, ‘FDuration’, and (ii) intensity of heat-stress, ‘FIntensity’, as when using evaporative pads, ‘EPads’. For the whole 5-month period (May–September) under Greek summer conditions strategy ‘FIntensity’ was significantly better than strategy ‘FDuration’ in terms of heat-stress duration (Po0.05; reduction 45.1%) and heat-stress intensity (Po0.01; reduction 70.7%). Also, during the hottest day (Julian 176) it resulted in: (i) a lower daily average inside temperature (28.5 vs. 31.8 1C; reduction 10.4%), (ii) a smaller daily inside dry-bulb temperature variation (8.7 vs. 10.3 1C; reduction 15.5%)
and (iii) a higher reduction of peak outside temperature (36.8 1C at 14:00 h), namely 2.9 vs. 0.2 1C, respectively. For both strategies and heat-stress indices July was the most stressful month and May the mildest. In areas characterised by high outside temperatures and scarce water resources strategy ‘FIntensity’ should be implemented with caution as larger water quantities, in comparison to strategy ‘FDuration’, need to evaporate.

For more information the full article can be found at  http://www.sciencedirect.com/science/journal/15375110

A comparison of the effects of dietary spray-dried bovine colostrum and animal plasma on growth and intestinal histology in weaner pigs

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This study was undertaken to evaluate the effects of dietary spray-dried plasma from two species (bovine and porcine) alongside spray-dried bovine colostrum in pigs weaned at 21 days of age, investigating the effect of these ingredients on small intestine histology, morphology and some indices of intestinal inflammation. It was found that compared to results from the control treatment, dietary spray-dried bovine colostrum reduced small intestine villus height at the site 25% along the small intestine, but increased it at the 75% site, whereas spray-dried bovine plasma increased villus height in the 25% and 75% sites, and spray-dried porcine plasma had no effect on villus height in any sampled region of the small intestine. Further research is needed to determine whether they are indeed functional alternatives, and where their similarities and differences may lie.

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

Entire male pigs in farrow-to-finish pens—Effects on animal welfare

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Castration performed without anaesthesia in piglets is a painful operation and it represents a potential animal welfare issue (Prunier et al., 2006). In an attempt to improve animal welfare, the Norwegian Parliament has passed a law banning the castration of piglets from 2009. Cessation of castration will relieve the animals from pain during and after surgery, but the rearing of entire males poses other welfare issues as entire male pigs are more aggressive and sexually active than castrates (Ellis et al., 1983; Giersing, 1998; Cronin et al., 2003). This could result in another animal welfare problem where high rank male pigs badger their pen mates of lower rank with biting, chasing and head knocks. Sexual behaviour (mounting of both gilts and boars) has also been reported as problematic, and can occasionally result in a high frequency of serious leg injuries to pen-mates (Rydhmer et al., 2004). It is important to recognise these problems and to find alternative rearing methods, which might ensure better animal welfare. Mixing of unacquainted pigs is usually followed by fighting (especially during the initial hours) until a new rank order is established in the group (Petherick and Blackshaw, 1987; Moore et al., 1994). The fighting behaviour tends to be more prolonged and serious when the weight differences between pigs are small (Rushen, 1987; Moore et al., 1994; Andersen et al., 2000; Schmolke et al., 2003). Mixing pigs is a very common practice in Norwegian pig production (and in many other countries also) both after weaning and when transferred to the fattening unit. The intention of the mixing is to reduce and balance the weight differences between pigs within the pens and to make the most out of available space. According to previous reports (Fredriksen et al., 2004), this practice can exacerbate sexual maturation of entire male pigs compared to when rearing them in sibling groups, in farrow-to-finish pens. Moreover, aggressive and sexual behaviour increases during puberty while mixing and moving animals. Furthermore reestablishment of the hierarchy among the pigs in the pen provokes aggressive and sexual behaviour. The hypothesis for the present study was that by keeping littermates together in stable groups, this process might be avoided and the onset of puberty delayed, thus resulting in a lower frequency of unwanted behaviour, lower skin lesion scores and consequently improved animal welfare. The frequencies of aggressive and sexual behaviour among finishing pigs were recorded in three different groups in one herd; farrow to finish-group (entires + gilts, siblings), mix-group (entires + gilts, mixed) and castrate-group (castrates + gilts, siblings). Frequencies of skin wounds were recorded in this herd and in an additional herd (only farrow to finish-group and mix-group) shortly before the animals were sent to slaughter. Higher skin lesion scores in the entire male pig groups were in accordance with the behaviour data. Rearing entire male pigs in sibling groups reduces aggressive behaviour, though the frequency of the aggressive behaviour bouts was still higher than it was in the castrate-group. The frequency of skin wounds in the farrow to finish-group was reduced to similar levels as in the castrate-group. The findings suggest that rearing entire males in sibling groups may be an appropriate management strategy for improving animal welfare in entire male pig production.

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

Social isolation elicits deficits in the ability of newly weaned female piglets to recognise conspecifics

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The goal of this study was to assess the ability of newly weaned female piglets to recognise familiar non-related
conspecifics and to examine how this was affected by weaning age and/or acute social isolation. It was found that neither weaning age nor social isolation affected the duration of social investigation in piglets exposed to unfamiliar conspecifics. However, when piglets weaned at day 11 were exposed to familiar conspecifics they investigated more than non-isolated pigs weaned on day 11, isolated piglets weaned on day 22 and non isolated pigs weaned at day 22. In conclusion, it may indicate that social recognition can be disrupted by 15 min of social isolation in piglets weaned on Day 11, but not in piglets weaned at Day 22.

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