Modification of the technical properties of Lactobacillus johnsonii NCC 533 by supplementing the growth medium with unsaturated fatty acids.

The aim of this study was to investigate the influence of supplementing growth medium with unsaturated fatty acids on the technical properties of the probiotic strain Lactobacillus johnsonii NCC 533, such as heat and acid tolerance, and inhibition of Salmonella enterica serovar Typhimurium infection. Our results showed that the membrane composition and morphology of L. johnsonii NCC 533 were significantly changed by supplementing a minimal Lactobacillus medium with oleic, linoleic, and linolenic acids. The ratio of saturated to unsaturated plus cyclic fatty acids in the bacterial membrane decreased by almost 2-fold when minimal medium was supplemented with unsaturated fatty acids (10 µg/ml). The subsequent acid and heat tolerance of L. johnsonii decreased by 6- and 20-fold when the strain was grown in the presence of linoleic and linolenic acids, respectively, compared with growth in oleic acid (all at 10 µg/ml). Following acid exposure, significantly higher (P < 0.05) oleic acid content was detected in the membrane when growth medium was supplemented with linoleic or linolenic acid, indicating that saturation of the membrane fatty acids occurred during acid stress. Cell integrity was determined in real time during stressed conditions using a fluorescent viability kit in combination with flow cytometric analysis. Following heat shock (at 62.5°C for 5 min), L. johnsonii was unable to form colonies; however, 60% of the bacteria showed no cell integrity loss, which could indicate that the elevated heat inactivated vital processes within the cell, rendering it incapable of replication. Furthermore, L. johnsonii grown in fatty acid-enriched minimal medium had different adhesion properties and caused a 2-fold decrease in S. enterica serovar Typhimurium UK1-lux invasion of HT-29 epithelial cells compared with bacteria grown in minimal medium alone. This could be related to changes in the hydrophobicity and fluidity of the membrane. Our study shows that technical properties underlying probiotic survivability can be affected by nutrient composition of the growth medium.

Reconstitution conditions for dried probiotic powders represent a critical step in determining cell viability.

AIMS: Resuscitation of dried cultures represents a critical control point in obtaining active and effective probiotic strains. This study examined the effects of various rehydration conditions on the viability of Bifidobacterium longum NCC3001 and Lactobacillus johnsonii La1. METHODS AND RESULTS: Reconstitution conditions for these strains were optimized using a multivariate experimental design approach. Furthermore, using flow cytometry, the cell integrity was followed during reconstitution. By adjusting the pH, availability of a metabolizable sugar, reconstitution duration, powder matrix and ratio of powder to reconstitution solution, the recovery of Bif. longum NCC3001 and Lact. johnsonii La1 following reconstitution was increased eight- and two-fold, respectively, over standard reconstitution in maximum recovery diluent. It was shown that pH had a significant effect on the recovery of Bif. longum NCC3001 and Lact. johnsonii La1. CONCLUSIONS: The recovery of dried probiotic cultures is greatly dependent on the reconstitution conditions. The maximum recovery of 11.7 (10)log CFU g(-1) Bif. longum NCC3001 was achieved at 30-min reconstitution at pH 8, in the presence of 2% L-arabinose and a ratio of 1:100 of powder to diluent. Lact. johnsonii La1 showed highest recovery (9.3 (10)log CFU g(-1)) after reconstitution, when mixed with maltodextrin at pH 4. SIGNIFICANCE AND IMPACT OF THE STUDY: To achieve accurate viable probiotic numbers from dried probiotic cultures, the reconstitution conditions should be optimized for the strain used.

Expanding the reach of probiotics through social enterprises.

The rapid rise in microbiome and probiotic science has led to estimates of product creation and sales exceeding $50 billion within five years. However, many people do not have access to affordable products, and regulatory agencies have stifled progress. The objective of a discussion group at the 2017 meeting of the International Scientific Association for Probiotics and Prebiotics was to identify mechanisms to confer the benefits of probiotics to a larger portion of the world's population. Three initiatives, built around fermented food, were discussed with different methods of targeting populations that face enormous challenges of malnutrition, infectious disease, poverty and violent conflict. As new candidate probiotic strains emerge, and the market diversifies towards more personalised interventions, manufacturing processes will need to evolve. Information dissemination through scientific channels and social media is projected to provide consumers and healthcare providers with rapid access to clinical results, and to identify the nearest location of sites making new and affordable probiotic food and supplements. This rapid translation of science to individual well-being will not only expand the beneficiaries of probiotics, but also fuel new social enterprises and economic business models.

Use of spermatozoa for artificial insemination. I. Fertilizing capacity of fresh and frozen spermatozoa in sows on 36 farms.

A field trial was conducted on 36 farms in the Netherlands to compare the fertilizing capacity of fresh and frozen-thawed boar spermatozoa. Four-hundred and fifty-one sows were artificially inseminated with semen than that had been frozen and thawed according to the Beltsville Method or diluted in Kiev extender and inseminated on the day of collection. Twelve boars of the Dutch Landrace and Dutch Large White breeds were used. Farrowing rates, total number of pigs per litter and number of live pigs per litter were higher (P less than .0001) for sows inseminated with fresh semen than for sows inseminated with frozen-thawed semen (79.1%, 10.6 and 9.9 vs 47.0%, 7.4 and 7.1, respectively). Farrowing rates for sows inseminated with frozen-thawed semen were higher when semen from Dutch Large White boars was used than when semen from Dutch Landrace boars was used (58.6 vs 40.9%); the pattern reversed for insemination with fresh semen (76.5 vs 81%). Boar differences based on farrowing rate ranged from 62 to 92% for fresh semen and from 29 to 72% from frozen semen. There was no inseminator effect or farm effect on farrowing rate. On the basis of these results, frozen semen used for artificial insemination under practical circumstances can be expected to result in a farrowing rate about 30 percentage points lower and a litter size about three pigs smaller than does fresh semen.

Methods of predicting pale, soft, exudative pork and their application in breeding programmes-A review.

The condition of pale, soft, exudative (PSE) pork has long been considered to be mainly a post mortem phenomenon. There is now substantial evidence that such pigs are suffering from a kind of myopathy, which predisposes them to an abnormal post mortem metabolism. Genetic studies on PSE muscle indicate a moderate heritability for various post mortem muscle quality traits. Reliable methods for determining the abnormal condition in the live animal would make it possible to select more effectively and economically against stress and PSE-susceptibility. Three possible methods are: (1) Analysis of blood serum for CPK, aldolase, GOT or other enzyme activities with and without preceding exercise; and for blood groups. (2) Muscle biopsy analysis for glucose-6-phosphate, lactate or energy-rich phosphates. (3) Non-destructive testing of young pigs for sensitivity to the Malignant Hyperthermia Syndrome by allowing them to inhale the anaesthetic halothane (fluothane) for a 5 min period. The development of muscular rigidity and stiffness indicates a susceptibility to stress and a potential for PSE meat. The relationships of the various methods to ultimate muscle and carcass quality, as well as the problems inherent to each method, are discussed. It is concluded that the third test seems to be the most promising for application in the breeding of pigs for optimal stress resistance and muscle quality.

Effects of feed withdrawal before delivery on pork quality and carcass yield.

A total of 270 pigs from a Yorkshire/Duroc/Landrace 3-way cross, reared under an ad libitum feed regimen, were delivered for slaughter after fasting (with access to water) for 24 and 0 h (Exp. 1), 16 and 0 h (Exp. 2) and 24, 16 and 0 h (Exp. 3). The interval between delivery and slaughter was 4-5 h. Feeding until delivery resulted in a lower pH at 45 min post mortem in the longissimus muscle. Ultimate pH values of longissimus and semimembranosus muscles were higher after feed restriction for 24 h. However, the incidence of dark, firm and dry (DFD) (pH > 6·2) was also increased after fasting in Exp. 1. Assessment of meat quality in samples taken from the longissimus at 20 h post mortem showed that, in comparison with feeding until delivery. Hunter L(∗) (Lightness)-values and drip loss decreased and firmness improved by prolonged fasting (24 h). Fasting for 16 h did not reduce drip loss, but colour was improved (lower Hunter L(∗)-values) in Exp. 3, although not in Exp. 2. Feeding until delivery resulted in better meat quality in Exp. 2 than in Exp. 1 and 3. A significant reduction in dressing percentage as a result of fasting was only found in Exp. 1. There appears no economic disadvantage in restricting feed for 16 h prior to delivery. Although the incidence of DFD may also increase, a fasting period of 16-24 h is recommended to reduce pale, soft and exudative (PSE) muscle, while losses in carcass yield are minimized. Other advantages of fasting are discussed.

Is colour brightness (L-value) a reliable indicator of water-holding capacity in porcine muscle?

A total of 265 pork carcasses representing a broad variation in quality was used to examine the relationship between colour (L-value) and water-holding capacity (WHC) in the longissimus thoracis et lumborum. Thirty-four samples appeared to possess 'normal' reddish pink colour (L-value 52·0-58·0) but had 'unacceptable' WHC (>5·0% drip loss). Conversely, 25 samples were pale in colour (L-value >58·0) but were 'acceptable' in WHC. When muscles were dark (L-value 52·0) the WHC was always acceptable. Some samples were subjected to further analysis. Variations in iron content, haematin content, sarcomere length and degree of soluble protein denaturation failed to explain why brightness and WHC were not more closely related. When L-value and WHC were compared to pH(45) (pH, 45 min post mortem), WHC exhibited a biphasic relationship to pH(45) whereas L-value did not. These results indicate that WHC and brightness are determined by independent pre-rigor biological phenomena, strengthening the argument that brightness is not necessarily a reliable predictor of WHC. Researchers selecting pork for specific investigations, or commercial companies using fresh pork for either further processing or for retail, should not rely on colour brightness alone to insure that other quality properties such as WHC and firmness will also be acceptable.

The effectiveness of examining early post-mortem musculature to predict ultimate pork quality.

Variations in pork quality reflect value differentials. However, only when they can be easily, accurately, rapidly and cost-effectively detected, can swine producers expect to eliminate poor quality from their herds through genetic selection, and can the industry be expected to take the necessary environmental precautions to prevent poor quality. This study was designed to assess the effectiveness of various techniques thought to predict ultimate pork quality through the examination of the physical and chemical properties of early post-mortem (PM) musculature. Based on stiffness and pH 30, 285 carcasses were selected. This selection procedure ensured a wide variation in ultimate quality. Using 12 instruments simultaneously, temperature, stiffness, electrical properties, lightness properties, and pH 45 of the early PM longissimus thoracis et lumborum were recorded to predict ultimate quality. Based on post-rigor light reflection and water-holding capacity (WHC), quality was assigned to one of five arbitrary groups. Of all techniques tested, the only one with any potential for adequate prediction of quality categories was pH 45. Combination of different techniques did not significantly increase predictive values. For predicting quality of single carcasses, pH 45 should not be considered satisfactory. However, based on our success in selecting carcasses representing quality variation for this study and the results obtained from the study, using pH 45 and muscle stiffness to select groups of carcasses is feasible. We conclude that the techniques used early post mortem are not appropriate for predicting ultimate pork quality for single carcasses. At present we recommend that only post-rigor muscle be considered, and that ultimate pH, light reflection and a measure of WHC should be used.

Highly cited article published in the Veterinary Quarterly in 1991.

In early 1991, the Dutch pig industry was struck by the so-called mystery swine disease. Large-scale laboratory investigations were undertaken to search for the aetiological agent. We focused on isolating viruses and mycoplasmas, and we tested paired sera of affected sows for antibodies against ten known pig viruses. The mycoplasmas M. hysonoviae, M. hyopneumoniae, and Acheloplasma laidlawii, and the viruses encephalomyocarditis virus and porcine enterovirus types 2 and 7 were isolated from individual pigs. An unknown agent however, was isolated from 16 of 20 piglets and from 41 of 63 sows. This agent was characterized as a virus and designated Lelystad virus. No relationship between this virus and other viruses has yet been established. Of 165 sows reportedly affected by the disease, 123 (75 per cent) seroconverted to Lelystad virus, whereas less than 10 per cent seroconverted to any of the other virus isolates or to known viral pathogens. Antibodies directed against Lelystad virus were also found in pigs with mystery swine disease in England, Germany, and the United States. We conclude that infection with Lelystad virus is the likely cause of mystery swine disease.

[Pigs as source animals for humans]. / Varkens als brondieren voor de mens.

This article reviews the current status of animal-to-human organ transplantation (xenotransplantion). In addition to immunological problems and the risk of disease, ethical issues with regard to both donor animals and humans make this technique not yet practicable. From further progress of this essentially veterinary development veterinary medicine and research will benefit.

[Transport of live-stock and process of slaughter (author's transl)]. / Diervervoer en slachtproces

The introduction on the transport of live-stock and the process of slaughter is mainly confined to transport and stunning as part of the processing of pigs as this presents a fair picture of the problems which also arise in the case of other animals. The study was promoted by problems of welfare both in the animals and in the people involved as well as by the need for modernization. The problems are due particularly to the advent of scale economies in slaughter-houses, the law failing to adjust itselt with sufficient rapidity. These problems will be solved most effectively by a good understanding between and interplay of research institutes and, for instance, the various executive veterinary services.

[Fractures of the scapula in pigs intended for slaughter (author's transl)]. / slachtvarkens

Fractures may be observed in the scapulae of those pigs intended for slaughter, which have undergone electrical stunning. These fractures may be classified into three types. That type in which the fracture is localized in the glenoid cavity is the most injurious one as it is accompanied by haemorrhage and therefore will result in loss of meat. This is liable to cause injuries to the employees engaged in boning out. It was concluded from an inquiry as well as from experimental exposure to stress that fractures of the shoulder are due to the marked tonic contractions of mainly antagonistic muscles, resulting in excessive strain on the shoulder blade and its joints. It is a striking fact that fractures of the shoulder were not observed in pigs stunned electrically while they were in a restraining apparatus.

[Electrical stunning of pigs intended for slaughter(author's transl)]. / Elektrisch beldwelmen val slachtvarkens

The present situation in electrical stunning of pigs intended for slaughter is described. The methods permitted by law are reviewed. In addition, the current situation which is marked by many imperfections, is discussed. These imperfections are due to inadequate awareness of the fact that the condition of the animal to be slaughtered is an important factor but also to matters closely related to the increasing economics of scale which are being adopted in pig slaughter-houses. Methods of restraining pigs at the time of stunning, the stunning apparatus (which often receives scant attention) and the interval between stunning and sticking are discussed. Studies in progress or being initiated in the Netherlands are reviewed; as a result of these studies, legal requirements may acquire that significance which they can be expected to have.

Application of probiotics in food products--challenges and new approaches.

The probiotic research conducted over the past 20 years has resulted in a valuable source of data related to health beneficial effects of probiotics. Nevertheless, documentation of probiotic benefits remains challenging, especially in functional foods that are designed for the generally healthy population that, however, regularly experiences episodes of 'suboptimal' health. In addition, in view of today's application of probiotics in an increasing variety of food matrixes, process optimization and product design need to take into account cell viability and probiotic function altogether. To meet this challenge, medium to high-throughput bioassays - based on the identification of active compounds and their mechanism of action - have to be developed and their predictive value established. Together with validated biomarkers for health and disease, this should help rationalize probiotic product development and associated health claim substantiation in human studies.