Ulrike Weiler

Nutritional Influences on Skatole Formation and Skatole Metabolism in the Pig.

Summary Skatole is a tryptophan metabolite with fecal odor. Skatole and the testicular steroid androstenone are regarded as the main compounds leading to ‘boar taint,’ a sex-specific odor from pork taken from entire males, as elevated concentrations of both substances may be found in adipose boars tissue. High skatole concentrations in adipose tissue are the result of a complex process, which includes microbial formation in the colon, absorption, metabolism and accretion in fat. Several of these steps leading to high skatole concentrations are influenced by feed components and additives. The present paper discusses the mechanisms by which effective feeding strategies and feed additives exert their influence in the prevention of high skatole concentrations in adipose pig tissue.

Serum IgA-Promoting Effects Induced by Feed Loads Containing Isolated Deoxynivalenol (DON) in Growing Piglets

Deoxynivalenol (DON), a Fusarium toxin belonging to the trichothecene group, has been reported to produce a variety of adverse health effects in farm animals, such as inhibition of protein synthesis, reduction of feed intake, and alteration of the immune system. In pigs, the effects of increasing levels of chemically pure DON in a semisynthetic diet on performance, health, and serum immunglobulin A (IgA) levels were examined. A diet, without grain components and trichothecene free (8 main trichothecenes), with doses of 0, 300, 600, and 1200 μg pure DON/kg was fed to 34 female pigs for a period of 8 wk after weaning under standardized conditions. Body weight gain and biochemical and hematological values in the blood and serum, including concentrations of IgA, blood glucose, cortisol, and insulinlike growth factor 1 (IGF-1), were determined. Increasing levels of DON in the feed induced a significant depression of glucose levels. Cortisol and IGF-1 levels were not significantly affected but differed between groups at the end of the experiment. A significant increase of IgA concentration in the serum even at a dosage level of 600 μg DON/kg feed was observed. This is the first report demonstrating in vivo that limited dosages of DON are able to stimulate IgA levels in the serum of growing piglets.

Influence of sex and immunocastration on feed intake behavior, skatole and indole concentrations in adipose tissue of pigs.

Feed intake behavior was studied between 9 weeks of age and slaughter in a total of 36 gilts, 32 immunocastrates, 33 surgically castrated barrows and 33 boars from 36 litters. Consequences for the concentration of substances contributing to off odor of pork (skatole, indole) were evaluated. Animals were kept in groups of 12 pigs of the same sex and treatment and fed ad libitum (13.4 MJ ME, 17% CP, 1.1% lysine). Individual feed intake behavior was recorded continuously by an electronic feeder. Immunocastration was carried out with two injections of Improvac with at least 4 weeks between both injections (1st: 12 to 17 weeks of age, 2nd: 19 to 21 weeks of age). Feed intake/day increased from an average of 0.91 ± 0.02 kg/day up to 3.15 ± 0.04 kg/day before slaughter. This increase was associated with a 50% reduction in the number of meals/day (from 15.8 ± 0.44 to 7.2 ± 0.29 meals/day). The larger meal sizes resulted from an increase in both, the duration of feed intake/meal and the feed intake rate (g/min). In addition, sex and treatment differences were observed: Feed intake in boars was lower than in all other groups due to a reduction in the number of meals/day and in the time spent feeding/day. In females, time spent feeding/day was quite similar to boars, but resulted from a higher number of meals of shorter duration. Barrows had a significantly higher feed intake because of a higher number of meals/day resulting in more time spent feeding/day. The feed intake rate was similar in boars, gilts and barrows and showed an increasing trend during the study, starting from about 15 g/min up to four times the amount. Immunocastration affected feed intake behavior severely, especially the meal size increased dramatically because of higher feed intake rate, which exceeded that of all other groups by 25% at the end of the study. The number of meals/day was not influenced by immunocastration and was almost identical to that of boars. Highest skatole concentrations were measured in fat of boars, whereas indole concentrations were higher in immunocastrates than in all other groups. In gilts and barrows, skatole concentrations were related to growth rate. Additionally, the feeding rate was an important factor explaining the variability in skatole/indole concentrations in adipose tissue. The physiological mechanisms however need further clarification.

Pre-slaughter conditions influence skatole and androstenone in adipose tissue of boars

Boar taint in carcasses may vary between farms and abattoirs, although the underlying mechanisms are not yet fully understood. In the present study, 169 boars from three farms were split into two groups and slaughtered at two abattoirs. Duration of transport and the time between arrival at the abattoir and unloading (pre-unloading time) were recorded. During slaughter, blood, feces, and urine were collected to measure testosterone and cortisol levels. Carcasses were classified according to the number of skin lesions, and fat samples were taken to determine skatole, indole and androstenone levels. Androstenone in fat and testosterone in blood, feces, and urine were mainly influenced by the duration of transport. Skatole and indole concentrations were increased by both pre-unloading time and duration of transport, but were also related to skin lesions. Thus it is concluded that androstenone and skatole concentrations in fat are significantly modified by pre-slaughter conditions.

Influence of sampling procedure, sampling location and skin contamination on skatole and indole concentrations in adipose tissue of pigs.

Skatole leads to off-odor in pork and is influenced by several factors such as sex and management conditions of pigs, but the causal relationships have not yet been clarified. In the present study, physiological skatole concentrations along the carcass were monitored and the transdermal diffusion of skatole was experimentally studied with skatole-spiked feces. Additionally, the impact of different biopsy techniques on skatole in fat and blood was studied. Monitoring of skatole along the carcass revealed higher skatole concentrations in the belly than in dorsal cuts. Topical application of spiked feces increased skatole in fat strictly at the application site. In contrast to punch biopsies, surgical biopsies significantly affected skatole and cortisol levels in blood, but not in fat. We conclude that biopsies for skatole measurements should be taken without anesthesia from the dorsal side of the animals. Fecal contaminations on the ventral side are not likely to influence overall concentrations.

Influence of Different Housing Systems on Distribution, Function and Mitogen-Response of Leukocytes in Pregnant Sows

Simple Summary The European Union imposes housing of pregnant sows in social groups since 2013 for animal welfare reasons. Nevertheless, the consequences of different housing conditions for the immune system of pregnant sows remain poorly investigated. We therefore analyzed important aspects of blood cellular immunity and cortisol concentrations of sows either housed in individual crates or in a group during gestation. The results show that individually housed sows had lower T cell numbers, but higher cortisol concentrations. Obviously, common housing conditions can differentially affect key elements of the adaptive immune system and hormonal indicators of stress in pregnant sows. Abstract In pig production, pregnant sows are either housed in individual crates or in groups, the latter being mandatory in the EU since 2013. The consequences of different housing conditions on the immune system are however poorly investigated, although immunological alterations may have severe consequences for the animal’s health, performance, and welfare. This study assessed measures of blood celluar immunity with special emphasis on T cells in pregnant German Landrace sows either housed in individual crates or in a social group. Blood samples were taken at four samplings pre partum to evaluate numbers of lymphocyte subpopulations, mitogen-induced lymphocyte proliferation and cytokine-producing T cells. Plasma cortisol concentrations were evaluated as an indicator of stress. We found lower blood lymphocyte numbers (p < 0.01) in individually housed as opposed to group-housed sows, an effect due to lower numbers of cytotoxic T cells, naive TH cells, and CD8+ γδ-T cells. Individually housed sows showed higher cortisol concentrations (p < 0.01), whereas lymphocyte functionality did not differ between sows of both housing systems. Possible implications and underlying mechanisms for the endocrine and immunological differences are discussed. We favor the hypothesis that differences in the stressfulness of the environment contributed to the effects, with crate-housing being a more stressful environment—at least under conditions of this study.

Diurnal rhythms in peripheral blood immune cell numbers of domestic pigs

ABSTRACT Diurnal rhythms within the immune system are considered important for immune competence. Until now, they were mostly studied in humans and rodents. However, as the domestic pig is regarded as suitable animal model and due to its importance in agriculture, this study aimed to characterize diurnal rhythmicity in porcine circulating leukocyte numbers. Eighteen pigs were studied over periods of up to 50 h. Cosinor analyses revealed diurnal rhythms in cell numbers of most investigated immune cell populations in blood. Whereas T cell, dendritic cell, and eosinophil counts peaked during nighttime, NK cell and neutrophil counts peaked during daytime. Relative amplitudes of cell numbers in blood differed in T helper cell subtypes with distinctive differentiation states. Mixed model analyses revealed that plasma cortisol concentration was negatively associated with cell numbers of most leukocyte types, except for NK cells and neutrophils. The observed rhythms mainly resemble those found in humans and rodents. HighlightsDomestic pigs exhibit diurnal rhythms in peripheral blood immune cell numbers.Immune cell rhythms in pigs mainly resemble those found in humans and rodents.Relative amplitudes and peak times differ among certain porcine immune cell types.Porcine immune cell counts were associated with plasma cortisol concentration.

Data characterizing diurnal rhythms in the number of peripheral CD8α− and CD8α+ γδ T cells in domestic pigs

This data article is related to the original research article “Diurnal rhythms in peripheral blood immune cell numbers of domestic pigs” of Engert et al. [1] and describes diurnal rhythms in the number of CD8α− and CD8α+ γδ T cells in peripheral blood of domestic pigs. Blood samples were taken from 18 animals over periods of up to 50 h and immune cell subtypes were determined by flow cytometry. Diurnal rhythmicity of cell numbers of γδ T cell subtypes was analyzed with cosinor analysis and different properties of rhythmicity (mesor, amplitude, and peak time) were calculated. In addition, associations between cell numbers of the investigated cell types in porcine blood with plasma cortisol concentration, hematocrit, and experimental conditions were identified with linear mixed model analysis.

Penile Injuries in Wild and Domestic Pigs

Simple Summary Male pigs raised for pork production on experimental and commercial farms were evaluated for scars, fresh wounds and severe injuries of the penis. A high incidence of penile injuries (64.0%–94.9% of the animals/farm) was found in boars but not in barrows (castrated males) with even severe wounds in 5.2% to 9.3% of the boars. A similar evaluation of 15 free-ranging wild boars also revealed a considerable proportion of animals with penile injuries. Thus, penis biting is a highly relevant and severe welfare problem in boars which is not limited to intensive production systems. Abstract In boars, sexually motivated mounting can not only cause problems such as lameness, but penile injuries are also reported. The relevance of penis biting in boars is discussed controversially, but reliable data is missing. In the present study, boars (n = 385) and barrows (n = 85) from experimental farms were therefore evaluated for scars, fresh wounds and severe injuries of the penis. Similarly, 321 boars from 11 farms specializing in pork production with boars, and 15 sexually mature wild boars from the hunting season of 2015/16 were included in the study. In domestic boars, a high incidence of penile injuries was obvious (76.6%–91.3% of animals with scars and/or wounds at experimental farms, 64.0%–94.9% at commercial farms). The number of boars with severe injuries was in a similar range in both groups (5.2% vs. 9.3%). At commercial farms, the number of scars but not that of fresh wounds increased per animal with age by 0.3 per week. Moreover, raising boars in mixed groups led to about a 1.5 times higher number of scars than in single-sex groups. In wild boars, a considerable proportion of animals (40%) revealed penile injuries, which were even severe in three animals. We therefore conclude that penis biting is a highly relevant and severe welfare problem in the male pig population, but this phenomenon is not limited to intensive production systems.

Attitudes of Serbian food technology students towards surgical and immunocastration of boars and their sensitivity to androstenone and skatole

Various European Union pork chain actors and stakeholders agreed in 2010 on a road map to voluntarily abandon piglet castration by 1 January 2018. Because currently in Serbia, male piglets are surgically castrated and consumers are not used to the boar taint odour and flavour, the introduction of boar meat may modify the acceptability of pork. The objective of the study was to investigate the attitudes, awareness and opinions of future Serbian food technologist towards surgical castration of boars and its alternatives, and to test their sensitivity to androstenone and skatole. We found that they were concerned about the animal welfare issues and that they were willing to pay a little more for meat from animals treated with dignity. This was more so if they were females and less so if they had had a rural upbringing. They strongly believed that surgical castration is painful for the animals, but at the same time agreed that meat from castrated pigs is of better quality. Their ambiguous attitudes regarding efficacy and quality of alternatives to surgical castration clearly indicated the knowledge gap that must be filled by appropriate modifications of the curriculum. Students demonstrated average sensitivity to both androstenone and skatole. Females exhibited higher intensities of difference in both cases.