Browsing by Person "Weiler, Ulrike"

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Exogenous influences on skatole formation in the pig
(2015) Wesoly, Raffael; Weiler, Ulrike
Castration of male piglets without anesthesia and analgesia has been an ancient and traditional practice in several European countries to prevent problems with boar taint. The commencement of the National Protection of Animals Act on 13th July 2013 intends to end castration without anesthesia in Germany by 2019. In Europe, the goal is to end castration of piglets by raising entire male pigs only from 2018 onwards. This, however, is a challenge for the entire supply chain of the pig production industry, since sufficient consumer protection from tainted boar meat cannot be guaranteed so far. Off-odors in boar meat are caused by the testicular steroid androstenone and the tryptophane metabolite skatole. Exogenous and endogenous factors which favor the formation of both boar taint substances, but especially of skatole, have so far been only partially identified. Thus the aim of the present thesis was to determine exogenous influences on skatole formation and deduce measures to reduce the amount of tainted carcasses. In the first part of the thesis (Chapter 3), the current state of research on the impact of feeding strategies on skatole physiology was summarized. The mechanisms of different feeding strategies and feed additives were described in their effect on formation, metabolism and fat deposition of skatole. Based on a deduced formation cascade of skatole, different feeding strategies aiming to reduce skatole can be evaluated in a simplified manner. It could be shown that promising feeding strategies to reduce skatole have to be effective on more than one level of the formation cascade at the same time. In the second part of this thesis (Chapter 4), the reasons for varying androstenone and skatole concentrations found at slaughter plants in animals from the same origin were investigated. In order to identify the reasons leading to said differences, a study with 169 boars from three different farms was conducted. Each farm delivered animals, split into two groups, to two different slaughter plants with a time interval of one day. The duration of transport as well as the duration of pre-unloading and the time spent on the vehicle before unloading were recorded. During the slaughter process, samples of blood, feces and urine were collected for hormone analysis. Carcasses were scored visually for lesions in cold storage after slaughter, and adipose tissue was removed for boar taint analysis. Even in animals of the same origin, the same genotype as well as the same feeding regimen, significant differences in androstenone and skatole concentrations in fat could be measured, which could be traced back to the different transport and pre-unloading times. In contrast to androstenone, skatole in the fat of the animals was influenced predominately by the pre-unloading time and increased by more than 20 ng/g with every hour of pre-unloading time. In addition, animals with higher lesion scores had higher skatole concentrations in fat. Transport time, on the other hand, had an effect on androstenone concentrations in fat, which increased by about 0.1 µg/g per hour transport. Skatole concentrations, however, were only slightly affected by transport time. Positive correlations could be found between cortisol and testosterone in various substrates with deposition of boar taint substances in fat. However, further research is required to clarify the mechanisms of these effects in detail. Minimizing transport and pre-unloading times before the slaughter process, however, seems mandatory to reduce the amount of tainted carcasses. The third part of this thesis (Chapter 5) investigated the impact of management factors on variability of skatole concentrations in blood and fat. Modern breeding companies take fat biopsy samples to estimate the breeding value for the trait boar taint in AI boars. However, it is not yet known to which extent repeated biopsies or different sampling locations may themselves affect skatole levels. Furthermore, the influence skin contamination of animals and of transdermal skatole diffusion have been matters of heated discussion for decades. The published results, however, are in part contradictory and it is not clear to which extent skatole can diffuse through the skin and to which degree this source may contribute to the concentrations in the carcass. As a consequence, the clarification of these complex relationships was the subject of the third study. The results show that skatole concentrations reveal a low variability in samples from the dorsal part of the carcass, although 20% higher concentrations were measured in the ventral area. The transdermal diffusion of skatole was confirmed in this study, but it was also shown that this diffusion is local and that skatole levels of the carcass in general were not increased. Repeated biopsies under total anesthesia temporarily increased skatole levels in blood and were accompanied by a similar course of cortisol concentrations in blood. Punch biopsies in conscious animals had no effect on the course of skatole or cortisol in blood. The present thesis illustrates that, besides nutrition, stress is an important factor for off-odors in boar carcasses. The results from the experimental studies suggest that an improvement of animal welfare can reduce the risk of off-odor in entire male pig production and thus contribute to consumer protection. However, the results also show that any success of the farmer in the reduction of boar taint can be partially undone on the way to slaughter.
Physiologische und genetische Einflüsse auf die Qualität von Schweinefleisch aus baden-württembergischen Gebrauchskreuzungen
(2012) Fecke, Anna; Weiler, Ulrike
What genotypes, basing on the genetic lines supplied by German Genetic, guarantees both a high-value carcass and excellent pork quality and high eating quality and also how the criteria of fertility, weight development and yield at slaughter, relate to the criteria of pork quality. 10 genotypes were studied. Therefore the sows crossbred represent typically genotypes in Baden-Württemberg as well as the Leicoma hybrid sows. These sows were bred at the LSZ Boxberg with Pietrain and Duroc boars. The sows of the LW*(LC*DL) had the highest fertility rate. The boar lines showed no influence on either the birth weight or fertility parameters. The boar line, however, did reflect a highly significant influence on the daily gain in all further production periods (Duroc vs. Pietrain: suckling +8%; rearing +3,8%; fattening +6,5%).The offspring from the sows LW*(LC*DL) had the greatest daily gain in the suckling period and had a higher weaning weight (+6%, p<0.05) than the offspring from the LW*(SH*DL), which achieved the lowest overall weaning weight. On analyzing the relationship between the development weights in the various production periods and the birth weight, it was obvious that the birth weight provides a significant positive influence on the performance in every production period, except for rearing. Indeed, in the rearing period the animals with a high birth weight tended to show low daily gains, whereas the piglets with a low birth weight were able to partially compensate for the early growth deficit during this period. The Pietrain offspring had more lean meat content than the Duroc offspring. The dissection in Trial #2 shows that the Pietrain offspring had 3.3% more ham content and 4.0% more of the valuable cuts. The Duroc offspring had less lean meat content in the belly (-4.2%, Gruber Formula), more back fat (+13.7%), more leaf fat (+14.6%), and 12.5% more corrected fat area than the Pietrain offspring. The offspring of the sows LC*LW had a significantly shorter carcass than the offspring of the other sows. The offspring from the 50% Leicoma sows showed the greatest corrected fat area. The offspring from the sows LW*(LC*DL) had 17.1% less corrected fat area. The correlation analysis resulted in the established relationships. Especially of a practical interest, is the close relationship between lean meat content (FOM) and the pork underbelly (Gruber Formula) (r=0.92; n=240; p<0.001). For nearly every parameter the results of the pork quality grading under practical conditions (Trial #1) tended toward improved values for the pigs with Duroc genes, which showed a significantly lower drip loss. The influence of the sows on pork quality parameters was negligible. Besides these parameters, some carcasses were also characterized with PSE qualities (pH1<5.8; conductivity 24hr p.m.>8.0mS/cm). In Trial #1, based on the pH-readings at the slaughterhouse, almost no carcasses (0.15%) were identified with PSE, whereas the conductivity measurements in ham, 5.79% of the carcasses were identified as PSE. In Trial #2, 15.0% of the animals were PSE based on pH1 or conductivity measurements in the loin and ham. There were 5 carcasses which have PSE after both measurements in loin and ham. In the histochemical analysis of the muscle fiber classification the only difference between the boar lines was found in the percentage of red fibers. The eating quality tests revealed an influence from the boar line. In general, all genotypes produced a high quality lean meat content according to the market requirements. As to expectation the improved pork quality of the Duroc breed was justified by the best eating quality, an improved water-holding capacity and a higher intramuscular fat content. An acceptable overall pork quality can be achieved by pairing the offspring from the Pietrain*LW*(LC*DL). The offspring with some Schwäbisch-Hall genes have an opportunity to establish a regional market. However, their performance was not convincing because in fertility, in daily gain, and even in pork quality they attained below average values. Nevertheless, an optimal pork quality can be achieved more efficiently with other genotypes. On establishing predicting criteria, the percentage of PSE of the pork carcasses is quite positive. The superiority of the 24hr p.m. conductivity value for the drip loss predict is evident here. The measurement of the conductivity subsume the effects of slaughtering and cooling and is more appropriate than the pH1 value, especially, for the incoming inspection in the deboning area as well as for quality assurance.
Wachstum und Wachstumsregulation beim Schwein
(1995) Weiler, Ulrike; Claus, Rolf
The endocrine regulation of growth was studied in wild and domestic pigs by systematic measurements of growth hormone (GH), IGF-I (Insulin-like growth factor-I), insulin and steroid hormones. In some of the studies measurements of osteocalcin were included to monitor the anabolic activity of osteoblasts under different physiological situations. The following results were obtained. Age dependent changes in the secretion of GH- und IGF-I were studied in growing boars, barrows and gilts and compared to growth parameters. IGF-I reflected age dependent changes in the growth potential and were closely correlated with daily gain and protein accretion. Osteocalcin concentrations were always correlated to IGF-I, the age dependent decrease, however, was more pronounced for osteocalcin than for IGF-I, reflecting the allometric predominance of skeletal growth in very young pigs. Osteocalcin concentrations were always correlated to IGF-I, the age dependent decrease was more pronounced for osteocalcin than for IGF-I, reflecting the allometric predominance of bone growth in very young pigs. Additionally a clear rhythm of IGF-I secretion was obvious with a period length of two to three weeks. This rhythm was similarly found for cortisol secretion and peripheral osteocalcin and might be related to allometric growth phenomena, as described for skeletal growth in other species. Regulation of GH-secretion includes interactions with hormones involved in the regulation of reproduction. At the pituitary level such interactions were demonstrated for Gn-RH and GH-RH. Gonadal steroids directly influence the release of GH and IGF-I secretion. The analysis of physiological situations as well as application studies revealed that testosterone had only a minor effect on both hormones. In contrast, low concentrations of estradiol clearly stimulated GH- and IGF-I secretion as well. Further increasing estradiol concentrations were still stimulatory for IGF-I but inhibited GH-secretion. Progesterone tended to lower both, GH and IGF-I secretion. Additionally Large White, Meishan and European wild boar were studied for differences in growth performance and the endocrine regulation during the first year of life. The studies revealed, that the high growth potential of LW is related both, to high levels of anabolic IGF-I and concomitantly low levels of catabolic cortisol. In Meishan and wild boars cortisol levels were high, but in Meishan boars additionally high concentrations of gonadal steroids were measured, which may explain the higher growth rate in MS when compared to wild boars. IGF-I concentrations were even higher in wild boars than in LW. Thus it is assumed that selection for growth potential led to a concomitant change in the level of catabolic glucocorticoids. The influence of the season and photoperiod on endocrine parameter, food intake and growth was investigated in wild and domestic boars. A seasonal influence on IFG-I secretion was obvious in wild and LW boars, but not in Meishan boars. It was further proven by the application of a reverse light programme that the pattern is mainly due to the influence of the photoperiod. In the wild boar three distinct metabolic periods were obvious, which were also found in domestic pigs, but less pronounced. In addition to the photoperiod food intake and food composition modulate GH and IGF-I secretion in the pig. Several experiments revealed, that IGF-I secretion is predominantly influenced by the energy supply and only to a lower extend by protein and tryptophane content of the ration.