Role of endothelin receptor activation in secondary pulmonary hypertension in awake swine after myocardial infarction

Posted in: Welfare by admin on January 1, 2006 | No Comments

Influence of rearing conditions on performance, behavioral, and physiological responses of pigs to preslaughter handling, carcass traits, and meat quality

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Societal concerns about conventional pig production have been increasing for a number of years in Europe. The conventional production system is generally thought to be associated with a negative environmental impact (pollution, offensive odors), and poor animal welfare due to high animal densities and bad housing conditions, and is perceived to result in reduced meat quality (Rainelli, 2001; Ngapo et al., 2003). Thus, in the near future, the pork industry has to propose pig production systems that satisfy consumer and citizen demands for lower environmental impact, improved animal welfare, and better meat quality. In this study a total of 120 crossbred [synthetic line × (Large White × Landrace)] pigs (castrated males and females) were used to evaluate the influence of rearing conditions for growing-finishing pigs on growth performance, carcass, stress reactions at slaughter, and meat eating quality. At approximately 35 kg of live weight (LW), littermates were allocated to either a conventional (fully slatted floor, 0.65 m²/pig, considered as control, CON) or an alternative (sawdust bedding with free access to an outdoor area, 2.4m²/pig, OUT) system, until slaughter at approximately 110 kg of LW. Pigs had free access to standard growing and finishing diets. The trials were conducted in spring, summer, and winter, with each season involving 2 pens of 10 pigs in each system. Compared with the CON, the OUT pigs exhibited a greater growth rate due to their greater feed intake, resulting in a greater body weight at slaughter. The OUT pigs had thicker backfat and lower lean meat content than the CON pigs. The OUT system did not influence the behavioral activities of pigs during lairage at the slaughterhouse, or the urinary levels of catecholamines and cortisol, and plasma levels of ACTH, cortisol, lactate, creatine kinase, and FFA immediately after slaughter. The OUT pigs had similar pH values 30 min postmortem in the lean meat, biceps femoris and semimembranosus muscles, but lower ultimate pH in semimembranosus muscles and in the backfat. Despite nonsignificant effects of production system on stress reactions at slaughter, assessed by urine and plasma indicators and muscle metabolism at 30 min postmortem, meat from OUT pigs had more lean meat drip loss after 2 and 4 days than did meat from the CON pigs. The OUT system slightly increased meat yellowness in the lean meat back fat, and semimembranosus muscles, whereas redness and lightness of the 3 muscles were unaffected. Also, intramuscular fat content was greater in the lean meat, backfat and semimembranosus muscles of the OUT pigs. It was also concluded that outdoor rearing during summer and winter improved meat juiciness, whereas odor, flavor, and tenderness were unaffected. Influence of rearing conditions on all the other traits studied did not depend on the season.

Phenotypic, Genetic and Epigenetic Variation of Immune Response and Disease Resistance Traits of Pigs

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The immune system is composed of integrated, genetically and environmentally regulated sets of cells and molecules that control the response to external and internal stimuli, including pathogenic microorganisms. In terms of infectious organisms, the response of the host largely reflects the relationship or adaptation between the host and agent. The variation in host response is influenced through genotype by environment interactions. Epigenetic effects are also highly sensitive to environmental influence and thus can rapidly alter individual phenotype. These are non-sequence alterations to DNA that cause changes in DNA structure that affect its availability for transcription. Consequently, disease is largely the product of incompatible gene by environmental interactions that include both genetic and epigenetic effects. These interactions vary at both the individual and population level. It is therefore particularly relevant to understand host-pathogen relationships and adaptations under various stress and management conditions. Improved understanding of the biology and genetic relationships between the host and pathogen, particularly those that affect the immune system during periods of production stress, should facilitate implementation of non-traditional approaches to improve the health of intensively reared livestock. This paper will briefly describe some of the genetic and environmental variation documented in immune response and performance traits of pigs, mainly using examples from experiments performed by the authors over the last two decades of research. Integrating quantitative and molecular genetic strategies to enhance the immune performance and improve inherent disease resistance of pigs, as well as other livestock species, has been the focus of much research. The data collected demonstrates that considerable phenotypic variation exists in immune response traits of pigs and that a substantial portion of that variation is due to additive genetic variance allowing for selective breeding of pigs with higher immune responsiveness. The underlying principle being that optimal disease resistance should be a function of optimal resistance-mediating defense mechanisms. Genes that underlie high or low immune responses and disease resistance are beginning to be understood, such as those within the MHC; however, selective breeding for complex disease traits should still be based on estimated breeding values of superior heritable phenotypes. The next step will be to evaluate high and low immune responsiveness and it’s influence on health and production traits in several commercial breeding nucleus herds.

Breeding Room: Body Condition, Feeding and Heat Detection

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Genetic selection in the past has maximized lean growth, which is a problem for reproduction. Strict nutritional programs must be followed in order to ensure proper body conditioning of the sow to maintain a quality reproductive life. Gestation feeding must be done to have the best possible body condition for farrowing, lactation, weaning, and return to estrus (all of which will be reduced by a too-fat sow). Sows that are too skinny will be more susceptible to injury. Each sow should be fed to individual requirements (a body score of 3 should be target). Modern feeders typically allow for examination and adjustment of each sows daily feed amount. Conditioning should be done at breeding, 30, 50, and 80 days of pregnancy. Feed increase in the 3rd trimester should be avoided unless absolutely necessary for the sow. An efficient breeding barn requires an understanding of the pigs’ estrus cycle, signs of pro-estrus, signs of heat, and heat detection. A cycle lasts from heat to heat (~ 21 days) and the sow can only be bred during heat. During the time before heat (pro-estrus) the vulva gets red and swollen and animal riding may occur. There are many signs of heat, but the most prominent is the standing heat reflex, where the sow permits breeding. Heat checking should be done nose to nose so the boar can stimulate the sow with sound and pheromones. Boars should be housed away from the sows in order to avoid the sows getting used to them and avoid an unknown refractory period.

Opportunities in Utilizing Crystalline Amino Acids in Swine

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Amino acid nutrition of monogastrics has been investigated using individual amino acids since the discovery of threonine by W. C. Rose in 1935. With commercial availability of synthetic methionine and crystalline lysine in the early 1960s, and because these two amino acids are typically first limiting in poultry and swine, there has been a plethora of research estimating their required needs. As additional crystalline amino acids became commercially available, tryptophan and threonine, and isoleucine and valine, research on their estimated requirements and ratios relative to lysine has expanded our understanding on how to formulate diets to minimize amino acid excesses while meeting the nutritional needs of the animal. Because of the increased availability of crystalline amino acids and the continual need to improve the utilization of nutrients to reduce the impact of livestock production on the environment, there is always a need to more fully understand amino acid nutrition of non-ruminants. In addition, characterization of ingredients or diets (total, apparent, standardized, or true, etc.), and method of data analysis, still present a difficult task of summarizing published data into a concise data set for ultimate use in feed formulation. Lastly, determination of nutrient requirement estimates in older or heavier animals is costly and inherently variable such that substantial progress in refining their nutrient needs has been difficult. However, progress in understanding nutrient needs of these animals is vitally important since consumption of feed is greatest, and conversion efficiency into edible product is lowest, at these heavier weights.

Weaning pig performance and faecal microbiota with and without in-feed addition of rare earth elements

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Two 6-week feeding trials were conducted on a total of 112 newly weaned piglets to examine the recently reported growth promoting effects of dietary rare earth elements (REE) in European pig production. Rare earth element-diets were supplemented with a REE-citrate premix of lanthanum and the light lanthanoides cerium, praseodymium and neodymium at 200 mg/kg for 6 weeks after weaning. Overall for both trials, growth performance of REE-citrate and control fed piglets did not differ significantly (p > 0.05). An early enhancive tendency for REE-citrate in trial 1 (feed conversion ratio, FCR )3%, p ¼ 0.15) proved irreproducible in trial 2. In the late period of trial 1, in-feed addition of REE-citrate significantly impaired piglet performance (FCR + 8%, p ¼ 0.01). A cultivation-independent molecular approach, polymerase chain reaction-denaturing gradient gel electrophoresis was further applied to assess REE induced alterations in the predominant faecal microbiota from weaning pigs. Calculation of various ecological characteristics does not indicate (p > 0.05) an often discussed selective effect on local microbial composition of dietary REE.

Recent Developments in Net Energy Research for Swine

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The cost of feed is the most important cost of pig meat production (~60%) and the energy component represents the greatest proportion of the feed. Therefore, it is important to estimate precisely the energy value of feeds, either for least-cost formulation purposes or for adapting feed supply to energy requirements of animals. In addition, energy supply has an important impact on performance of animals. Evaluation of energy content of pig feeds is firstly and most commonly based on their Digestible Energy (DE) or Metabolizable Energy (ME) contents. However, the closest estimate of the “true” energy value of a feed should be its Net Energy (NE) content, which takes into account differences in metabolic utilization of ME between nutrients. In addition, NE is the only system in which energy requirements and diet energy values are expressed on a same basis, which should theoretically be independent of the feed characteristics. The objectives of this paper is to present the available energy systems for pig feeds with emphasis given to NE systems and to evaluate their ability for predicting pig performance. Energy value of pig feeds can be measured according to different criteria (DE, ME or NE). The most advanced and practically applicable energy evaluation system appears to be the NE system proposed by Noblet et al. (1994) for which energy values of most ingredients used in pig diets are available (Sauvant et al., 2004). In addition, these authors have proposed energy values that are different for growing and adult pigs. This system has been widely used in Europe and internationally in many major feed companies. The relative energy density or the hierarchy between ingredients depends on the energy system with considerable variations between ingredients or compound feeds when either fat or crude protein contents deviate from values in standard diets. Even if it has not been considered in detail in this review, the change from DE or ME systems to a NE system is usually associated with a shift in diet composition with lower crude protein contents and slightly higher fat levels. From that point of view, formulating according to a NE concept produces more environmentally friendly diets. Significant improvements in prediction of energy value of pig feeds will come from an improved knowledge of energy and nutrients digestibility, which depends on chemical characteristics of the feed, (bio)technological treatments and animal factors. Unfortunately, current information is insufficient to take this systematically into consideration and it should be a promising area for future research. Finally, for least cost formulation purposes, reliable (i.e., related to animal performance) nutritional values must be used. It is then highly suggested to combine efficient protein – digestible amino acids – and energy – net energy – systems. Under such circumstances, the feed cost of production should be minimized.

Effect of incorporating biogas slurry (BGS) on the growth performance and carcass traits of growing pigs

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Component and Factor Analysis of Pork Farm Odour using Structural Learning with the Forgetting Method

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In pig farming, odour measurement and reduction are necessary for a cleaner environment, lower health risks to humans, and higher quality of pig production. There have been many studies on the modelling of pork farm odour by analysing the chemical components in odorous air. It is suggested that the component analysis approach should be extended to factors such as temperature, relative humidity, and airflow speed. However, previous component and factor analysis did not examine which components or factors contribute significantly to a complex odour. A relative contribution analysis of potential odour components and factors to the perception of odour would allow identification of significant odour components and major contributing factors. Odour reduction practice for pork farms could then be directed towards the significant components and factors, thus improving the efficiency in developing odour measurement and reduction technologies. It is generally accepted that neural networks have several advantages over conventional techniques, for instance, their ability to automatically learn the relationship between the inputs and outputs without any previous
knowledge of the system being studied, their powerful generalisation ability, and their capability of handling non-linear interactions. However, typical neural network models suffer from the so-called ‘black box’ problem, i.e. it offers no information about the system other than the input/output relationship. In this paper, existing methods for odour strength prediction were reviewed, and a neural network based multi-component multi-factor odour model was developed. To reveal the relative contribution of the inputs, the neural network was trained using an algorithm called structural learning with forgetting. By applying the structural learning with forgetting based algorithm, unnecessary neural connections faded away and a skeletal network emerged. The resulted skeletal network enabled an analysis of the contribution of components and factors. The effectiveness of the proposed approach was demonstrated by simulation and comparison studies.

An Overview of Danish Pork Industry Integration and Structure

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In the beginning of the 1970s there were 40 to 50 cooperative slaughterhouses in Denmark, and in 2005 the number has decreased to 2. Today, Denmark processes 22 million pigs equalling 1.9 million tons of pork. Danish Crown is the biggest pig processor in the European Union, accounting for 8% of the pigs slaughtered. The Danish pork industry is highly export oriented (85% exported). The cooperative structure of the Danish pork industry is considered a very important factor in the success of the industry on a global basis because they can develop a very high level of food safety and traceability. The Danish pork industry has built its reputation on the capabilities of supplying requested volumes and quality of pork to processors all over the world. Denmark has implemented a system for full traceability of the individual animal from farm to slaughterhouse. Denmark has strong research capacities within primary production and processing of pigs. Environmental regulations and scarcity of land have put a limit on future expansion of pig production. In the future, pork trade will increase particularly in Japan, China, and South East Asia, each of which Denmark already exports to. Increased competitiveness must come from economies of scale, flexibility, proximity to the market, and increased internationalization.