Immunogenicity of porcine circovirus type 2 capsid protein targeting to different subcellular compartments

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

Porcine circovirus type 2 (PCV2) is known to be associated with post-weaning multisystemic wasting syndrome (PMWS), an emerging disease in swine. The development of effective vaccines against PCV2 infection has been accepted as an important strategy in the prophylaxis of PMWS, and a DNA vaccine expressing the major immunogenic capsid (Cap) protein of PCV2 is considered to be a promising candidate. However, recent studies have revealed that interferons (IFNs), especially IFN-, can enhance the replication of PCV2, indicating that the high levels of IFN- induced by DNA vaccination seem to have potential deleterious effect on protective immunity. Strategies to improve the  neutralizing antibody response and simultaneously decrease the IFN- response will facilitate the clinical application of DNA vaccines against PCV2. In the present study, four different DNA vaccine constructs encoding cytoplasmic (Cy-ORF2), secreted (Sc-ORF2), membrane-anchored (M-ORF2) or authentic nuclear-targeted (pc-ORF2) Cap protein were generated to evaluate the neutralizing antibody and IFN- responses in a mouse model. Although all four DNA constructs could elicit PCV2-specific humoral immune responses, mice inoculated with Sc-ORF2 developed a significantly higher level of neutralizing antibodies than those that received M-ORF2, pc-ORF2 or Cy-ORF2. Furthermore, mice immunized with Sc-ORF2 or M-ORF2 showed a significantly decreased or enhanced IFN- level, respectively, compared with those inoculated with pc-ORF2.With respect to neutralizing antibody and IFN- levels, Sc-ORF2 is a good candidate for DNA vaccination, and the secreted Cap protein appears to be an ideal antigen for use in development of vaccines against PCV2.

For more information the full article can be found at http://www.sciencedirect.com/science/journal/01615890

The effect of varying lengths of straw bedding on the behaviour of growing pigs

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Since January 2003, the provision of appropriate environmental enrichment to pigs of all ages has been a legal requirement in the EU. The Directive states that: ‘To enable proper investigation and manipulation activities, all pigs must have permanent access to a sufficient quantity of material such as straw, hay, wood, sawdust, mushroom compost, peat or a mixture of such which does not adversely affect the health of the animals’. European animal welfare legislation is built on the principle that all animals have intrinsic value. Animals should therefore be able to express species-specific behaviour. The pig has a propensity to express nosing, rooting and chewing behaviours as a result of both exploratory and feeding motivation (Fraser et al., 1991; Day et al., 1995, 1996b. When individuals are not able to express these behaviours in barren housing environments, the activity may be channeled towards inappropriate stimuli such as pen-mates (Lawrence et al., 1993). Straw has been reported to improve the welfare of pigs housed in barren environments, because it can be used as a recreational substrate, as a nutritional substrate and as a bedding material (Fraser et al., 1991; Arey and Bruce, 1993; Lyons et al., 1995; Van de Weerd et al., 2005b; Tuyttens, 2005). However, it is still not really clear how straw functions to modify behaviour and what it exactly is about straw that makes it so effective in occupying a pig (Van de Weerd, 2005a). Therefore it is important to gain knowledge about the properties of straw that are behaviourally rewarding for pigs (Day et al., 2001b). The acquisition of such knowledge can then be applied to facilitate the construction of environmental enrichment devices which meet the behavioural needs of pigs, whilst also being compatible with partly and fully slatted housing systems (Van de Weerd et al., 2003). The present study explored the efficacy of providing pigs with small quantities of chopped straw, as opposed to full-length straw, since the former material could be used in partly and fully slatted systems with less risk of blockage of the liquid slurry handling facilities. To investigate this, groups of growing pigs were exposed to treatments where the provision and length of straw varied. Twenty-four groups of growing pigs were exposed to one of four treatments (no straw bedding, full-length straw, half chopped straw, and fully chopped straw). Both pen-mate- and straw directed behaviours were recorded using ad libitum sampling. It was found that the length of straw affected both the quantity and quality of straw-directed behaviours. The provision of straw of any length reduced the occurrence of behaviours such as nosing other pigs, aggression and tail-biting compared with when straw was absent. Chopped straw increased the prevalence of behaviours such as licking and decreased the prevalence of behaviours such as picking, suggesting that pigs were not able to manipulate the chopped straw in the same way as full-length or half chopped straw. In addition, levels of tail-biting were higher in groups that were provided with chopped straw than in groups with full-length or half chopped straw. It is concluded that the use of chopped straw in growing/finishing housing systems, whilst better than no enrichment, is inadvisable because of the possibility that levels of adverse pen mate directed behaviours will increase.

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

Social discrimination of familiar conspecifics by juvenile pigs, Sus scrofa: Development of a non-invasive method to study the transmission of unimodal and bimodal cues between live stimuli

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A non-invasive method was developed to study the transmission of cues that are used in social
discrimination by pigs, Sus scrofa. We investigated the ability of juvenile pigs to discriminate between
pairs of familiar, similar-aged conspecifics in a Y-maze learning task, using either single or paired visual,
olfactory and auditory cues. The stimulus pigs (n = 12) were littermates that were familiar but unrelated to
the test pigs (n = 12). For the bimodal task, test pigs (four per treatment) were presented with cues of two
modalities: olfaction and vision (OV), vision and audition (AV), or audition and olfaction (AO).
Approaches to a pre-determined correct stimulus were rewarded with food in daily sessions, each of
10 consecutive trials. Three consecutive successful sessions of 8/10 correct choices (P = 0.00016)
fulfilled the criterion for starting the unimodal task, during which test pigs were given either olfactory,
visual or auditory cues only using the same success criterion. Eight pigs learnt the bimodal task (OV: 4,AV:
2,AO: 2) ofwhich six pigs subsequently completed the unimodal task successfully (O: 3,V: 2, A: 1). These
findings indicate that juvenile pigs have the cognitive capacity to discriminate between same-sex
littermates that are also familiar group-members in the absence of either visual, olfactory or auditory cues, and that some can use just one of these modalities. A larger-scale study is needed to determine the sensory hierarchy of social discrimination in pigs.

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

Do citizens and farmers interpret the concept of farm animal welfare differently?

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This study provides a quantification of the similarities and differences between aspects relating to farm animal welfare as valued by farmers and citizens and tries to explain the findings based on differences in values, interests, knowledge, norms and convictions, constituting the frame of reference of the perception towards farm animal welfare. The interpretation of the complex and multi-dimensional concept of farm animal welfare has proven to be quite compatible from a citizen and farmer perspective. The main differences are found in the importance attached to animals’ ability to engage in natural behaviour and in aspects which require some basic understanding about production conditions and the way livestock is reared. Furthermore, citizens evaluated the current state of farm animal welfare rather negative with mean evaluative belief scores for almost all aspects below the mid-point of the scale, while a much more positive image was present among farmers. Discordance between citizen and farmer perception appeared to be the highest for aspects related to natural behaviour, pain, stress and availability of space.

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

The effect of microbial phytase on true and apparent ileal amino acid digestibilities in growing-finishing pigs

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In this study ten 56 day old barrows were surgically fitted with a postvalvular T-cecum cannula to evaluate the effect of microbial phytase on apparent and true ileal amino acid (AA) digestibility and nitrogen (N) utilization. It was found that the addition of phytase to a semipurified soybean meal-based diet did not affect the apparent ileal digestibility of several amino acids. Also, difference between the basal and homoarginine (HA) diets in nitrogen digestibilities indicated that the guanidination may limit the use of the HA method in determining endogenous proten losses

Effect of soluble and insoluble fiber on energy digestibility, nitrogen retention, and fiber digestibility of diets fed to gestating sows

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This research paper determines how soluble (SF) and insoluble fibre (ISF) effects energy digestibility, Nitrogen balance, and digestibility. It was concluded that increased intake of insoluble firbre decreased energy digestibility, whereas increasing soluble fibre improved energy digestibility. The diet had not effect on nitrogen retention. Insoluble fiber digestiblity improved when SF intake increased, which suggests that knowledge of specific dietary fiber components is necessary to predict effeects of dietary firbew on digestibility.

Genetic associations of sow longevity with age at first farrowing, number of piglets weaned, and wean to insemination interval in the Finnish Landrace swine population

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The objective of the study was to estimate
genetic parameters for length of productive life
(LPL), and determine its genetic correlation with age
at first farrowing (AFF), number of piglets weaned at
first farrowing (NW), and first wean-to-insemination
interval (W2I) in the Finnish Landrace swine population.
Data from the Finnish national litter recording
scheme were utilized to estimate the genetics of LPL,
and genetic associations between LPL, AFF, NW, and
W2I. Data from the Finnish Landrace sow records were
utilized from farms that farrowed more than 20 gilts
annually from 2000 through 2005. The data set included
information from 11,222 sows, all of which had AFF
and NW information available. The sows producing the
records evaluated were daughters of 1,267 sires, and
there were 3,684 animals in the pedigree when all of
the sires were traced back to founder animals. All data
were obtained from FABA Breeding (Vantaa, Finland).
Multivariate Bayesian analysis of Gaussian, right censored
Gaussian, and categorical traits was utilized to
estimate (co)variance parameters of LPL, AFF, NW,
and W2I of the sow. From these traits, AFF and NW
were treated as Gaussian, LPL as right-censored Gaussian,
and W2I as categorical traits. Estimated posterior
means of heritabilities were 0.22, 0.16, 0.09, and 0.08
for LPL, AFF, NW, and W2I, respectively. A relatively
large proportion of variance due to farm-year interaction
was observed (posterior means of f2 ranged between
0.03 and 0.26). The LPL was moderately genetically
correlated with NW and AFF (posterior means
were –0.20 and 0.36, respectively), whereas no clear
association was found between W2I and LPL. Favorable
genetic correlations between AFF and W2I and
between NW and W2I were also observed. Additionally,
an unfavorable genetic correlation between AFF
and NW was observed in the present data set. Because
LPL is genetically associated with other economically
important prolificacy traits, it should be included in a
multiple trait swine breeding value estimation system.

Use of phytogenic products as feed additives for swine and poultry

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Phytogenic feed additives are plant-derived products used in animal feeding to improve the performance of agricultural livestock. This class of feed additives has recently gained increasing interest, especially for use in swine and poultry, as can be derived from a significant increase in the number of scientific publications since 2000. This appears to be strongly driven by the ban on most of the antibiotic feed additives within the European
Union in 1999, a complete ban enforced in 2006, and ongoing discussions to restrict their use outside the European Union because of speculated risk for generating antibiotic resistance in pathogenic microbiota. In this context, phytogenic feed additives are discussed possibly to add to the set of nonantibiotic growth promoters, such as organic acids and probiotics, which are already well established in animal nutrition. Phytogenics, however, are a relatively new class of feed additives and our knowledge is still rather limited regarding their modes of action and aspects of their application. Further complications arise because phytogenic feed additives may vary widely with respect to botanical origin, processing, and composition. Most studies investigate blends of various active compounds and report the effects on production performance rather than the physiological impacts. This article summarizes the experimental knowledge on efficacy, possible modes of action, and aspects of application of phytogenic products as feed additives for swine and poultry. Phytogenic feed additives comprise a wide variety of herbs, spices, and products derived thereof, and are mainly essential oils. The assumption that phytogenic compounds might improve the palatability of feed has not yet been confirmed by choice-feeding studies. Although numerous studies have demonstrated antioxidative and antimicrobial efficacy in vitro, respective experimental in vitro evidence is still quite limited. The same applies to the supposition that phytogenic compounds may specifically enhance activities of digestive enzymes and nutrient absorption. Nevertheless, a limited number of experimental comparisons of phytogenic feed additives with antibiotics and organic acids have suggested similar effects on the gut, such as reduced bacterial colony counts, fewer fermentation products (including ammonia and biogenic amines), less activity of the gut-associated lymphatic system, and a greater prececal nutrient digestion, probably reflecting an overall improved gut equilibrium. In addition, some phytogenic compounds seem to promote intestinal mucus production. Such effects may explain a considerable number of practical studies with swine and poultry reporting improved production performance after providing phytogenic feed additives. In total, available evidence indicates that phytogenic feed additives may add to the set of nonantibiotic growth promoters for use in livestock, such as organic acids and probiotics. However, a systematic approach toward the efficacy and safety of phytogenic compounds used as feed additives for swine and poultry is still missing.

Effect of common antinutritive factors and fibrous feedstuffs in pig diets on amino acid digestibilities with special emphasis on threonine

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The objective of this experiment was to determine the apparent ileal digestibilities (AID) of ammino acids of 6 ANF-enriched diets to estimate endogenous protein loss associated with these ingredients in diets for young pigs. It was concluded that the data suggested that hemicellulose fiber, at typical concentrations, reduces AID of amino acids by increasing endogenous losses.

Genetic (co)variances and breeding value estimation of Gompertz growth curve parameters in Finnish Yorkshire boars, gilts and barrows

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This paper’s objectives were to estimate the genetic (co)variance components
of the Gompertz growth curve parameters and to evaluate the
relationship of estimated breeding values (EBV) based on average daily
gain (ADG) and Gompertz growth curves. It was found that the growth curves differ significantly between individuals and this information could be used for selection purposes when selecting for improved growth rate.