改进集约化养猪生产环境的措施

为建立和改善养猪生产环境，提高集约化养猪生产水平。综合分析了集约化猪场生产环境中存在的主要问题，介绍了改善和治理养猪生产环境的措施和方法。     

A survey of swine production health problems and health maintenance expenditures

Swine producers in the Missouri Mail-In-Record program provided information on herd health problems, death losses and health maintenance expenditures in their swine herd for the years 1978 and 1979. Swine health problems and death losses dampen profits for swine producers. During the study period approximately one-third of all pigs raised by Missouri Mail-In-Record swine panel producers were affected by health problems. It is important for swine producers to keep health problems under control. Important health problems for swine producers were scours, pneumonia, salmonellosis, TGE, and influenza. Important death causal factors were crushing or trauma, scours, lack of milk, and pneumonia. Health problems and death losses were most severe during the first quarter of the year. The major swine health expenditure was for services which were farmer administered. On a relative basis smaller producers depended more on veterinarians for seervices than did larger producers. Also, producers that had more than one type of production technology (pasture, confinement, etc.) tended to have larger animal health expenditure levels.     

The concentration of swine production. Effects on swine health, productivity, human health, and the environment.

The concern about environmental issues centering around CAFOs is appropriate. The veterinary profession can be an important force in meeting these challenges by broadening its scope of knowledge and practice into the broader environmental field. Although animal agriculture's contribution to environmental concerns is the focus of this article, it is only one of several sectors that contributes to environmental degradation. Crop production, as well as livestock production industries, contribute to pollution. Manufacturing industries, municipalities, private individuals, our consumptive lifestyles, and agriculture all contribute to the degradation of our environment. One must keep in mind the huge importance of our agricultural industry and not single it out to the detriment of its progress. We have an abundance of high-quality foods at the lowest cost to the individual of any industrialized nation. We export over 40 billion dollars in agricultural products yearly. Agriculture sustains our rural economies and provides opportunities for over 2 million private enterprises scattered across the country; however, there is a goal that we have a sustainable agriculture. A big part of that depends on development and enhancement of an agriculture that does not pollute, that sustains its farm operators and workers, and that does not make the area residents ill or degrade their quality of life; however, the current situation is not promising. Much remains to be learned about the actual acute and long-term health consequences of animal agricultural pollution. Many health concerns are speculative, even though based on sound facts. We know that many surface waters have excess N and P that leads to eutrophication and possibly enhanced growth of undesirable organisms such as Pfiesteria piscicida. We know that other animal pathogens, such as cryptosporidia, have caused large community outbreaks. There are other potential pathogens, such as Salmonella sp, for which we do not know the hazard. We know that our soils may become excessively laden with P, Cu, and Zn, which retard plant growth and create toxic conditions for grazing animals. There are concerns about air pollution. Odors have negative sensory and physical health consequences. H2S and dust may cause toxic effects on neighbors. NH3 vaporizing from manure sources may be carried with precipitation to cause eutrophication in lakes or altered ecosystems in natural areas. CH4 escaping from degrading manure contributes to greenhouse gases. Workers in confined livestock structures have high risk for a variety of chronic respiratory conditions. They also are at risk for acute poisoning from H2S in operations where liquid manure is stored in confined spaces. There have been numerous health complaints in recent years from community neighbors of large-scale livestock operations. One study showed adverse altered mood states, and another showed evidence of respiratory illness similar to what workers experience. Although it has not been possible to objectively measure conditions and know toxic levels of substances causing these illnesses, there are so-called extratoxic mechanisms, such as inherent aversion to putrefactive odors and exacerbation of preexisting conditions that lower the tolerance threshold. Environmental concerns regarding livestock production are not new. In the early and mid-1970s, there were many conferences and publications regarding odors and water contamination from livestock operations. Although most of what is known in this area has been known for 20 years, relatively little effective efforts have been made to correct the concerns. In fact, trends over this past decade have increased the concerns. This past decade has seen a tremendous acceleration in the concentration and consolidation of agriculture, capping a slow trend over the past 50 years toward larger, fewer, and more-specialized farms. This trend has gone against the old saying that "dilution is the solution to pollution.     

Biological markers of boar fertility

The semen evaluation techniques used in most commercial artificial insemination centers, which includes sperm motility and morphology measurements, provides a very conservative estimate of the relative fertility of individual boars. As well, differences in relative boar fertility are masked by the widespread use of pooled semen for commercial artificial insemination (AI) in many countries. Furthermore, the relatively high sperm numbers used in commercial AI practice usually compensate for reduced fertility, as can be seen in some boars when lower numbers of sperm are used for AI. The increased efficiency of pork production should involve enhanced use of boars with strong reproductive efficiency and the highest genetic merit for important production traits. Given that the current measures of semen quality are not always indicative of fertility and reproductive performance in boars, accurate and predictive genetic and protein markers are still needed. Recently, significant efforts have been made to identify reliable markers that allow for the identification and exclusion of sires with reduced reproductive efficiency. This paper reviews the current status of proteomic and genomic markers of fertility in boars in relation to other livestock species.     

Using genetic markers for disease resistance to improve production under constant infection pressure

Animals will show reduced production when exposed to a constant infection pressure unless they are fully resistant, the size of the reduction depending on the degree of resistance and the severity of infection. In this article, the use of QTL for disease resistance for improving productivity under constant infection pressure is investigated using stochastic simulation. A previously published model was used with two thresholds for resistance: a threshold below which production is not possible and a threshold above which production is not affected by the infection. Between thresholds, observed production under constant infection is a multiplicative function of underlying potential production and level of resistance. Some simplifications of reality were adopted in the model, such as no genetic correlation between potential production and resistance, the absence of influence of lack of resistance on reproductive capacity, and the availability of phenotypes in both sexes. Marker-assisted selection was incorporated by assuming a proportion of the genetic variance to be explained by the QTL, which thus is defined as a continuous trait. Phenotypes were available for production, not for resistance. The infection pressure may vary across time. Results were compared to mass selection on production under constant as well as intermittent infection pressure, where the infection pressure varied between but not within years. Selection started in a population with a very poor level of resistance. Incorporation of QTL information is valuable (i.e., the increase in observed production relative to mass selection) when a large proportion of the additive genetic variance is explained by the QTL (50% genetic variance explained) and when the heritability for resistance is low (h2R = 0.1). Under constant infection pressure, incorporating QTL information does not increase selection responses in observed production when the QTL effect explains less than 25% of the genetic variance. Under intermittent selection pressure, the use of QTL information gives a slightly greater increase in observed production in early generations, relative to mass selection on observed production, but still only when the QTL effect is large or the heritability for resistance is low. The additional advantage of incorporating QTL information is that use of (preventive) medical treatment is possible, or animals may be evaluated in uninfected environments.     

Design and standards for genetic evaluation of swine seedstock populations

The purpose of this article is to describe a program for evaluation of seedstock populations in the swine industry. Differences among seedstock populations for economically important traits must be identified in order for pork producers to efficiently use available genetic resources. National genetic evaluation programs have the potential to identify the important differences among populations and to increase the rate of genetic improvement in a population. Program results provide performance benchmarks that stimulate testing and selection procedures by seedstock suppliers that further increase the rate of genetic improvement. A Terminal Sire Line Genetic Evaluation Program was designed and conducted in the United States by the National Pork Producers Council (Des Moines, IA) to compare seedstock populations for use in crossbreeding systems. High levels of statistical accuracy for program results were established; the ability to detect differences of 0.25 SD per trait, a power of test of 75%, and a 5% significance level were selected. Pure breeds and breeding company sire lines were nominated for the program. Semen was collected from nominated boars and distributed to cooperating commercial producers during eight 1-wk breeding periods. Pigs were produced in 136 commercial herds and transported to testing facilities at 8 to 23 d of age. Nine of the 11 sire lines originally entered in the program completed the sampling requirements for statistical analysis. High levels of statistical accuracy and a large, representative sample of boars with restrictions on genetic relationships ensured that the program results included unbiased, highly accurate sire line data for growth, carcass, meat quality, and eating quality traits of economic importance. This program has shown commercial producers that they have several choices of sire lines for changing their crossbreeding programs in desired trait areas. Commercial product evaluation must be an ongoing process, and this program serves as a model for future testing and evaluation of diverse genetic seedstock populations.     

Disease prevention in swine production

First, it is mentioned that the health status of the population of Swiss swines is very good in comparison to other nations due to the activity of the pig health service (PHS) and that in many places the conditions for a reduction of the use of antimicrobials are already there. Then, the activity of the PHS is described. Its success is base on the obstinate implementation of the eradication programs which are already widely used at the present time in several regions of Switzerland and which have attracted interested specialized practitioners. How the renouncement of the use of antimicrobial growth promoters will affect PHS and non PHS herds remains to be determined. A special paragraph lists the reasons why practitioners often have only little access to swine herds. One reason is the lack of competence. This problem should be solved by an intensification of the graduate and postgraduate education. Finally, the argument for a valorization of an applied and problem-oriented research at the faculties should be put forward.     

Antimicrobial resistance in swine production

Large amounts of antimicrobial agents are still being used in modern swine production in many countries around the world. This facilitates the emergence and development of antimicrobial resistance. Bacteria causing infections in swine have in several cases acquired resistance to a number of the agents most commonly used for treatment, making it difficult to predict the efficacy of different antimicrobial agents without prior susceptibility testing. This review gives an overview of recent susceptibility data from different parts of the world and discusses the importance of the development of resistance not only in the treatment of infections in swine but also taking into account the human health implications of antimicrobial resistance.     

Selection for placental efficiency in swine: genetic parameters and trends

The objectives of this study were to estimate response to divergent selection for an index of placental efficiency in swine, and to evaluate the effect of placental efficiency on litter size. The selection index (SI) included total born (TB), birth weight (BRWT), and placental weight (PW), and was designed to increase in the high line (H) or decrease in the low line (L) the efficiency of the placental function (PE), defined as the ratio BRWT:PW. (Co)variance components were estimated for direct and maternal additive effects by using an animal model with MTDFREML procedures. Estimated breeding values were calculated by using records on individual BRWT (n = 2,111), PW (n = 2,006), PE (n = 1,677), and SI (n = 1,677). Litter traits were evaluated using records on 193 litters. The model included the fixed effects of contemporary group for all traits, with the addition of sex for individual traits and parity for litter traits. Litter was fitted as an uncorrelated random effect for all traits, and TB was used as a linear and quadratic covariate for BRWT, PW, and PE. Direct heritability estimates from single-trait models were 0.03, 0.25, 0.18, 0.11, and 0.08 for BRWT, PW, PE, SI, and TB, respectively. Estimated breeding values were compared between lines by using a model including generation, line within generation, and replicate within line as the error term. Estimates of genetic divergence were 20.7 +/- 2.7 g, 0.24 +/- 0.03, 0.11 +/- 0.02, and 0.07 +/- 0.02 per generation for PW, PE, SI, and TB, respectively (P < 0.01), but divergence was not significant for BRWT. At Generation 4, direct EBV was higher in L than in H for PW (55.9 +/- 8.7 vs. -24.2 +/- 9.5 g, respectively; P < 0.01) and higher in H than in L for PE (0.58 +/- 0.10 vs. -0.35 +/- 0.09 g, respectively; P < 0.01). However, EBV was not different for BRWT, SI, or TB. These results indicate that PW and PE are susceptible to change by genetic selection; however, the correlated response in TB was an unexpected genetic trend toward a higher TB in L of 0.05 +/- 0.01 piglets per generation (P < 0.01).     

Biochemical markers of bone metabolism in animals: uses and limitations

Routine assessment of the skeleton's response to disease and injury traditionally has consisted of plain-film radiography supplemented with advanced imaging techniques, such as computed tomography, magnetic resonance imaging, nuclear scintigraphy, and bone densitometry. Although these techniques provide increased sensitivity as compared with radiography, they still are limited by the fact that they can only document the net results of past skeletal activity. In contrast, serum and urinary biomarkers of bone formation and resorption provide near real-time information about bone cell activity. In this review, I describe the scientific rationale behind the use of these markers in humans and detail the efforts that have been made to adapt this technology to veterinary medicine and animal research. Commercial assay kits that are applicable to different animal species are described, and the potential limitations of the technology are discussed. The goal of this review is to provide clinical pathologists and researchers with the information needed to decide whether the use of bone markers is likely to be helpful and to select the most appropriate marker (or panel of markers) to answer a particular question.     

半胱胺在养猪生产中的应用

半胱胺(CS)是动物体内的生物活性物质。大量研究表明,半胱胺具有不同程度的促生长作用,且能提高饲料报酬,改善胴体品质,提高母猪的繁殖性能。本文就半胱胺的作用机制及其在养猪生产中的应用作一综述。