Long-term changes in performance and meat quality of Danish Landrace pigs: a study on a current compared with an unimproved genotype

The color of fresh pork: Consumers expectations, underlying farm-to-fork factors, myoglobin chemistry and contribution of proteomics to decipher the biochemical mechanisms

The color of fresh pork is a crucial quality attribute that significantly influences consumer perception and purchase decisions. This review first explores consumer expectations and discrimination regarding pork color, as well as an overview of the underlying factors that, from farm-to-fork, contribute to its variation. Understanding the husbandry factors, peri- and post-mortem factors and consumer preferences is essential for the pork industry to meet market demands effectively. This review then delves into current knowledge of pork myoglobin chemistry, its modifications and pork discoloration. Pork myoglobin, which has certain peculiarities comparted to other meat species, plays a weak role in determining pork color, and a thorough understanding of the biochemical changes it undergoes is crucial to understand and improve color stability. Furthermore, the growing role of proteomics as a high-throughput approach and its application as a powerful research tool in meat research, mainly to decipher the biochemical mechanisms involved in pork color determination and identify protein biomarkers, are highlighted. Based on an integrative muscle biology approach, the available proteomics studies on pork color have enabled us to provide the first repertoire of pork color biomarkers, to shortlist and propose a list of proteins for evaluation, and to provide valuable insights into the interconnected biochemical processes implicated in pork color determination. By highlighting the contributions of proteomics in elucidating the biochemical mechanisms underlying pork color determination, the knowledge gained hold significant potential for the pork industry to effectively meet market demands, enhance product quality, and ensure consistent and appealing pork color.

The Muscle Fibre Characteristics and the Meat Quality of M. Longissimus Thoracis from Polish Native Złotnicka Spotted Pigs and the Crossbreed Fatteners from the Crossing of Duroc and Polish Large White Boars

The aim of the investigations were to assess the meat raw material of the domestic Złotnicka Spotted swine breed as well as its hybrids with Duroc and Polish Large White breeds with respect to quality, technological usefulness, and muscle fibre composition and structure. The suitability of individual swine genetic groups (Złotnicka Spotted × Złotnicka Spotted, Złotnicka Spotted × Duroc, Złotnicka Spotted × Polish Large White, Złotnicka Spotted × Złotnicka Spotted/Duroc) for the production of heavy fatteners which can be used as slaughter raw material to manufacture raw and raw-ripening meat products was ascertained. Złotnicka Spotted pigs were characterised by a statistically significantly smaller proportion of IIB fibres and a higher share of I and IIA fibres in the longissimus thoracis muscle in comparison to the hybrids of this breed with Duroc and Polish Large White breeds. The diameter of all muscle fibre types in the longissimus thoracis muscle of the Złotnicka Spotted breed was greater than in hybrids. No statistically significant differences were found between the parameters of colour and the free drip and the water absorbability of the loin of the Złotnicka Spotted breed pigs and their hybrids with Duroc and Polish Large White breeds. The examined meat was characterised by a small free drip and good water absorbability. The hybrid pigs (Złotnicka Spotted x Duroc) were characterised by the highest content of intramuscular fat (IMF) in the longissimus thoracis muscle, which resulted in the lowest sheer force of roasted loin and the lowest thermal drip compared to other hybrids. Smoked, raw loin obtained from the longissimus thoracis muscle of the Złotnicka Spotted breed was found to be the most tender, whereas tenderness of the identical loin derived from the longissimus thoracis muscle of the Złotnicka Spotted bred hybrids with the Duroc and Polish Large White breeds was poorer. Due to the small headage of the Złotnicka Spotted breed, the appropriate numbers of fatteners of good meat quality parameters suitable to manufacture raw, ripening meat products can only be secured by the crossing of this breed with other meat breeds. Therefore, it appears that crossing the Złotnicka Spotted pigs with Duroc pigs would be a suitable solution.

Effects of Using Corn Dried Distillers' Grains with Solubles (cDDGS) as a Partial Replacement for Soybean Meal on the Outcomes of Pig Fattening, Pork Slaughter Value and Quality

Simple Summary

Soybean meal is the principal component of the diets for fattener pigs; however, there is a constant need for alternative, inexpensive, preferably non-GMO (genetic modified organisms) protein sources in swine nutrition. Corn dried distillers’ grains with solubles (cDDGS), by-products of ethanol and bioethanol production, are one such alternative. Due to their chemical composition, they cannot completely replace soybean meal; however, even relatively small additions of cDDGS may decrease the cost of feeding and increase profitability of pig production. In this study, the pigs were fed two different diets: control (cereal–soybean meal-based) or cDDGS (with soybean meal partially replaced with cDGGS). The growth performance as well as carcass and meat quality traits of fatteners fed cDGGS-containing diets did not differ from those of their respective controls. However, the addition of even 15% of cDDGS did result in lower production costs and increased the profitability of pig fattening.

Abstract

The present study set out to determine the effects of incorporating cDDGS into starter, grower, and finisher diets (containing 5%, 10%, and 15% of cDDGS, respectively) on growth performance, carcass and meat quality, and cost effectiveness of pig fattening. Sixty-four pigs (mean body weight of 15.0 ± 2.1 kg) were divided into two groups (n = 32) and fed a control diet (cereal–soybean meal-based) or cDGGS-containing diets (with soybean meal partially replaced with cDDGS). Live weights of pigs as well as weight gains/daily weight gains across all fattening phases did not differ between the two groups of fattener pigs studied (p > 0.05). Addition of cDDGS decreased feed intake per pig during the grower (p < 0.05) and finisher (p < 0.01) phases, and, as a result, throughout the entire fattening period (254 vs. 245 kg for control and cDDGS groups, respectively; p < 0.01). The feed conversion ratio (FCR) for the entire fattening period was significantly less for cDDGS-fed fatteners (2.77) than for controls (2.91; p < 0.05). Carcass weights, fat thickness, and meatiness did not vary between the two groups of animals (p > 0.05). Loin depth was greater in the cDDGS group by ~5 mm (p < 0.05). Slaughter value was higher for the cDDGS group (76.1% vs. 77.0%, p < 0.05). The total cost of fattening and total cost of 1 kg of body weight decreased in cDDGS compared with the control subset of fatteners by ~7% and 8% during the grower and finisher phases, respectively (p < 0.01). The simplified direct surplus per pig was approximately 63% higher for the cDDGS group. Our results indicate that even moderate inclusion of cDDGS to concentrate mixtures (or a partial replacement of soybean meal with cDDGS) may improve FCR without any substantial changes in meat and back fat characteristics as well as significantly decrease the cost of feeding and increase the profitability of pig production.

Greater liver PNPLA3 protein abundance in vivo and in vitro supports lower triglyceride accumulation in dairy cows

Fatty liver syndrome is a prevalent metabolic disorder in peripartum dairy cows that unfavorably impacts lactation performance and health. Patatin-like phospholipase domain-containing protein 3 (PNPLA3) is a lipase that plays a central role in human non-alcoholic fatty liver disease etiology but has received limited attention in bovine fatty liver research. Thus, we investigated the relationship between tissue PNPLA3 expression and liver triglyceride accumulation in vivo via a ketosis induction protocol in multiparous dairy cows peripartum, as well as in vitro via small interfering RNA knockdown of PNPLA3 mRNA expression in bovine primary hepatocytes. Results demonstrated a negative association (P = 0.04) between liver PNPLA3 protein abundance and liver triglyceride content in peripartum dairy cows, while adipose PNPLA3 protein abundance was not associated with liver triglyceride content or blood fatty acid concentration. Knockdown of PNPLA3 mRNA resulted in reduced PNPLA3 protein abundance (P < 0.01) and greater liver triglyceride content (P < 0.01). Together, these results suggest greater liver PNPLA3 protein abundance may directly limit liver triglyceride accumulation peripartum, potentially preventing bovine fatty liver or accelerating recovery from fatty liver syndrome.

Quality characteristics of fresh loin and cooked ham muscles as affected by genetic background of commercial pigs

This study was performed to investigate meat quality traits of loin and ham of commercial pigs as affected by genetic differences in carcass and growth traits of the parent lines. Three hybrid sow lines were crossbred with two types of Belgian Piétrain with different breeding goals (BP_growth and BP_carcass emphasizing daily growth and carcass conformation, respectively). Pig live performance and carcass quality of 270 offspring were measured, and meat quality of the loin and (cooked) ham was evaluated on 216 animals. Despite the differences in pig live performance and carcass quality for sow line, little effect on meat quality was observed. Only a lower (p < 0.05) intramuscular fat content of ham and a tendency (p < 0.1) toward lower cooking yield was observed in offspring of the sow line with the highest versus the lowest carcass lean content. Loin traits were only weakly associated with fresh and cooked ham quality traits.

Meat Texture Profile and Cutting Strength Analyses of Pork Depending on Breed and Age

The chemical composition and culinary meat tenderness belong to the most important characteristics determining meat quality and value. The aim of this work was to compare texture profiles and shear force of pork loin (m. longissimus dorsi) and of pork ham (m. semimembranosus) from fatteners of Polish Landrace (PL), Polish Large White (PLW), Duroc, Pietrain and Puławska pig breeds slaughtered at 60, 90, 120, 150, 180 and 210 d of breeding. Meat was roasted at 180°C to inner temperature of 78°C. The intramuscular fat (IMF) content in loin was growing with fattener age (from 1.17% at 60 d to 1.84% at 180 d of life). Between breeds IMF ranged from 0.82% in PLW to 2.29% in Puławska breed. The shear force for loin muscle ranged from 3.42 kG/cm2 at 60 d to 6.54 kG/cm2 at 210 d of life while for and ham muscle 4.4 kG/cm2 at 60 d to 6.78 kG/cm2 at 210 d of life. The hardness (TPA) ranged from 72.29 N at 90 d of life to 109.46 N at 210 d of life. The shear force of loin and ham meat was increasing with age of fatteners and some texture parameters – hardness and chewiness. Nevertheless it seems that the age of 150 days is the time when meat of fatteners is characterized by the highest technological properties. However, the final decision regarding slaughter age should be made taking into account the technological destination of the carcasses. No significant interactions between the animal breed and their age were found for the parameters analysed.

Myosin Heavy Chain Composition, Rate of Dystrophin and Integrin Degradation and Meat Quality of Pig Longissimus thoracis and psoas major Muscles During Postmortem Aging

This study evaluated myosin heavy chain composition and the effect of aging time (45 min, 24 h, 96 h and 168 h) on meat quality parameters and dystrophin and integrin degradation pattern in longissimus thoracis and psoas major muscles of 24 Polish Landrace fatteners slaughtered at 100 kg body weight. It was found that m. longissimus thoracis had a greater percentage of MyHC-IIB (P≤0.05) and a significantly lower percentage of type I and IIA/IIX (P≤0.05) compared with the m. psoas major. Moreover, psoas major muscle had significantly higher (P≤0.05) pH45, pH24 and lower drip loss values for 45 min to 24 h, 45 min to 96 h and 45 min to 168 h than m. longissimus thoracis. Muscle type also had a significant effect on the rate of dystrophin and integrin degradation postmortem, which were significantly (P≤0.05) more rapidly degraded in the m. longissimus thoracis compared to the m. psoas major. It is concluded from the obtained results that the muscles with a greater percentage of MyHC-IIB show lower pH values, which translates into more rapid rate of integrin and dystrophin degradation. Ultimately, this may contribute to higher drip loss values during refrigerated storage.

Glucose metabolism is differentially altered by choline and methionine in bovine neonatal hepatocytes

Choline and methionine serve essential roles in the liver that may interact with glucose metabolism. Our objectives were to quantify glucose export, cellular glycogen, and expression of genes controlling oxidation and gluconeogenesis in primary bovine neonatal hepatocytes exposed to increasing concentrations of choline chloride (CC) and D,L-methionine (DLM) with or without fatty acids (FA). Primary hepatocytes isolated from 3 Holstein calves were maintained as monolayer cultures for 24 h before treatment with CC (61, 128, 2028, 4528 μmol/L) and DLM (16, 30, 100, 300 μmol/L) with or without a 1 mmol/L FA cocktail in a factorial design. After 24 h, media was harvested to quantify glucose, β-hydroxybutyrate (BHB), and cells harvested to quantify glycogen, DNA, and gene expression. No interactions between CC and DLM were detected. The potential two-way interaction between CC or DLM and FA was partitioned into three contrasts when P ≤ 0.20: linear without FA, linear with FA, difference of slope. Fatty acids did not affect glucose or cellular glycogen but increased pyruvate carboxylase (PC), cytosolic and mitochondrial phosphoenolpyruvate carboxykinase (PEPCKc, PEPCKm), and glucose-6-phosphatase (G6PC) expression. Increasing CC decreased glucose but increased cellular glycogen. Expression of PC and PEPCKc was increased by CC during FA treatment. Increasing DLM did not affect metabolites or PC expression, although PEPCKc was marginally decreased. Methionine did not affect G6PC, while CC had a marginal quadratic effect on G6PC. Oxidative and gluconeogenic enzymes appear to respond to FA in primary bovine neonatal hepatocytes. Increased PC and PEPCKc by CC during FA treatment suggest increased gluconeogenic capacity. Changes in G6PC may have shifted glucose-6-phosphate towards cellular glycogen; however, subsequent examination of G6PC protein is needed. Unaltered PC and marginally decreased PEPCKc suggest increased oxidative capacity with DLM, although BHB export was unaltered. The differential regulation supports unique effects of CC and DLM within bovine hepatocytes.

Muscle characteristics in chicks challenged with Salmonella Enteritidis and the effect of preventive application of the probiotic Enterococcus faecium

The present study was conducted to assess the effects of the probiotic Enterococcus faecium AL41 (EF) and of the enteric pathogen Salmonella Enteritidis PT4 (SE) on the development of posthatch pectoralis major muscle (PM) of broiler chicks. The four experimental groups were control (CON), EF, SE, and EF+SE (EFSE). EF and SE were given per os from days 1 to 7 and at day 4 posthatch, respectively. Muscle samples from 6 chicks per group were taken at day 8 (D8) and day 11 (D11) to evaluate PM myofiber growth, capillarization, DNA, RNA, and protein content, as well as enzyme activities (isocitrate dehydrogenase, lactate dehydrogenase, creatine kinase). PM growth rate was 7.45 ± 2.7 g/d in non-SE groups (CON, EF) and 5.10 ± 1.82 g/d in SE-infected groups (P < 0.02). Compared with group CON, application of bacteria (groups EF and SE) reduced the fiber cross-sectional area (246 and 262 vs. 347 ± 19 μm2) and the number of myonuclei per fiber (0.66 and 0.64 vs. 0.79 ± 0.03). At D11, hypertrophic myofiber growth normalized in the EF group, but negative effects persisted in SE and EFSE birds contributing to lower daily PM gain. In addition, SE infection strongly disturbed PM capillarization. Negative effects on capillary cross-sectional area and on the area (%) covered by capillaries persisted until D11 in the SE group, whereas pre-feeding of EF restored capillarization in the EFSE group to control levels. We conclude that supplementation of the probiotic bacteria EF AL41 had positive effects on PM capillarization and, thus, on delivery of O2, supply of nutrients, and removal of metabolites. Supplementation of probiotic bacteria might therefore reduce energetic stress and improve muscle health and meat quality during SE infection.

Supplementation of sows with L-Arginine during gestating and lactation affects muscle traits of offspring related with postnatal growth and meat quality: From conception to consumption

This study investigated the effect of dietary inclusion of 25 g/day of _L-Arginine (n = 7) or iso‑nitrogenous amounts of alanine (n = 6) from d 30 of gestation to d 28 of lactation of sows on performance, muscle traits and meat quality in offspring. From each litter, heaviest and smallest littermate of both sexes were reared from d 28 and slaughtered at d 140 in accordance with a 2³factorial design. A response to _L-Arginine were obtained on small females where _L-Arginine increased birth weight, however this effect disappeared at weaning. _L-Arginine increased daily gain by 7% and increased the cross-sectional area of the M. semitendinosus in small females by 14%, suggesting an increased lean ratio. Mechanistic studies showed firstly, that small female littermates had increased number of muscle fibres (myogenesis) after _L-Arginine treatment (11%) and secondly increased total DNA (12%) as a consequence of satellite cell proliferation. Traits describing tenderness seem to be affected by _L-Arginine but further studies are needed.

Bone mineralisation, mechanical properties and body phosphorus content in growing gilts as affected by protein or feed intake during depletion-repletion periods

The influence of feed or protein depletion-repletion on phosphorus balance, and bone characteristics was studied on 70 growing pigs from 90 to 168 d of age. During depletion period (90-118 d of age), C pigs were fed semi ad libitum (95% ad libitum intake) on control diet; FR pigs (feed-restricted group) consumed 40% less of control diet compared to C pigs; PR pigs (protein-restricted group) were fed semi ad libitum a low-protein diet containing 40% less protein than control diet. During repletion period (119-168 d of age), daily allowances for C pigs were equal of 95% ad libitum intake. Remaining pigs consumed a control diet at the same amount as C pigs. Pigs were slaughtered at 90 d of age ("zero" animals, n = 7), following seven animals from each group at d 118, 146 and 168  of age. At 118 d of age, phosphorus content in the body was lower (p < 0.001) in FR than C and PR pigs. Lower phosphorus deposition and utilisation was observed in FR animals. Humerus in FR pigs was lighter, had lower mineral content and density, but had greater stiffness than in PR and C pigs. During repletion period, FR pigs deposited more phosphorus and had better phosphorus utilisation than C and PR pigs. Humerus mineral density was greater in FR and PR than in C pigs. Humerus strength was the highest in PR pigs, and the lowest in FR pigs. Humerus stiffness was greater in PR than in C and FR pigs. In conclusion, during depletion period feed restriction affects bone growth more than protein restriction, and bone strength is less sensitive, than other bone characteristics, to feed restriction. Reductions in measured bone indices observed after lower feed intake can be fully compensated during the repletion period and resulted mainly from better utilisation of minerals.

Voluntary locomotor activity promotes myogenic growth potential in domestic pigs

Self-determined physical activity is an essential behavioural need and can vary considerably between individuals of a given species. Although locomotion is suggested as a prerequisite for adequate function of skeletal muscle, domestic pigs are usually reared under limited space allowance. The aim of our study was to investigate if a different voluntary locomotor activity leads to altered properties in the muscle structure, biochemistry and mRNA expression of selected genes involved in myogenesis and skeletal muscle metabolism. Based on a video tracking method, we assigned pigs to three categories according to their total distances walked over five observed time points: long distance, medium distance, and short distance. The microstructure and biochemistry parameters of the M. semitendinosus were unaffected by the distance categories. However, we found distance-dependent differences in the mRNA expression of the genes encoding growth (IGF2, EGF, MSTN) and transcription factors (MRF4, MYOD). In particular, the IGF2/MSTN ratio appears to be a sensitive indicator, at the molecular level, for the locomotor activity of individuals. Our results indicate that the myogenic growth potential of pigs under standard rearing conditions is triggered by their displayed voluntary locomotor activity, but the covered distances are insufficient to induce adaptive changes at the tissue level.

TRIENNIAL GROWTH AND DEVELOPMENT SYMPOSIUM: Genetics and breeding for intramuscular fat and oleic acid content in pigs

The intramuscular fat (IMF) and oleic acid (OL) content have been favorably related to pork quality and human health. This influences the purchasing behavior of consumers and, therefore, also shifts the attention of breeding companies toward whether these traits are included into the breeding goal of the lines producing for high-valued markets. Because IMF and OL are unfavorably associated with lean content, a key economic trait, the real challenge for the industry is not simply to increase IMF and OL, but rather to come up with the right trade-off between them and lean content. In this paper we review the efforts performed to genetically improve IMF and OL, with particular reference to the research we conducted in a Duroc line aimed at producing high quality fresh and dry-cured pork products. Based on this research, we conclude that there are selection strategies that lead to response scenarios where IMF, OL, and lean content can be simultaneously improved. Such scenarios involve regular recording of IMF and OL, so that developing a cost-efficient phenotyping system for these traits is paramount. With the economic benefits of genomic selection needing further assessment in pigs, selection on a combination of pedigree-connected phenotypes and genotypes from a panel of selected genetic markers is presented as a suitable alternative. Evidence is provided supporting that at least a polymorphism in the leptin receptor and another in the stearoyl-CoA desaturase genes should be in that panel. Selection for IMF and OL results in an opportunity cost on lean growth. The extent to which it is affordable relies on the consumers' willingness to pay for premium products and on the cost to benefit ratio of alternative management strategies, such as specific dietary manipulations. How the genotype can influence the effect of the diet on IMF and OL remains a topic for further research.

Moderate high or low maternal protein diets change gene expression but not the phenotype of skeletal muscle from porcine fetuses

The aim of our study was to characterize the immediate phenotypic and adaptive regulatory responses of fetuses to different in utero conditions reflecting inadequate maternal protein supply during gestation. The gilts fed high- (250% above control) or low- (50% under control) protein diets isoenergetically adjusted at the expense of carbohydrates from the day of insemination until the fetuses were collected at day 64 or 94 of gestation. We analyzed body composition, histomorphology, biochemistry, and messenger RNA (mRNA) expression of fetal skeletal muscle. Both diets had only marginal effects on body composition and muscular cellularity of fetuses including an unchanged total number of myofibers. However, mRNA expression of myogenic regulatory factors (MYOG, MRF4, P ≤ 0.1), IGF system (IGF1, IGF1R, P ≤ 0.05) and myostatin antagonist FST (P = 0.6, in males only) was reduced in the fetal muscle exposed to a maternal low-protein diet. As a result of excess protein, MYOD, MYOG, IGF1R, and IGFBP5 mRNA expression (P ≤ 0.05) was upregulated in fetal muscle. Differences in muscular mRNA expression indicate in utero regulatory adaptive responses to maternal diet. Modulation of gene expression immediately contributes to the maintenance of an appropriate fetal phenotype that would be similar to that observed in the control fetuses. Moreover, we suggest that the modified gene expression in fetal skeletal muscle can be viewed as the origin of developmental muscular plasticity involved in the concept of fetal programming.

Genetic Marker Discovery in Complex Traits: A Field Example on Fat Content and Composition in Pigs

Among the large number of attributes that define pork quality, fat content and composition have attracted the attention of breeders in the recent years due to their interaction with human health and technological and sensorial properties of meat. In livestock species, fat accumulates in different depots following a temporal pattern that is also recognized in humans. Intramuscular fat deposition rate and fatty acid composition change with life. Despite indication that it might be possible to select for intramuscular fat without affecting other fat depots, to date only one depot-specific genetic marker (PCK1 c.2456C>A) has been reported. In contrast, identification of polymorphisms related to fat composition has been more successful. For instance, our group has described a variant in the stearoyl-coA desaturase (SCD) gene that improves the desaturation index of fat without affecting overall fatness or growth. Identification of mutations in candidate genes can be a tedious and costly process. Genome-wide association studies can help in narrowing down the number of candidate genes by highlighting those which contribute most to the genetic variation of the trait. Results from our group and others indicate that fat content and composition are highly polygenic and that very few genes explain more than 5% of the variance of the trait. Moreover, as the complexity of the genome emerges, the role of non-coding genes and regulatory elements cannot be disregarded. Prediction of breeding values from genomic data is discussed in comparison with conventional best linear predictors of breeding values. An example based on real data is given, and the implications in phenotype prediction are discussed in detail. The benefits and limitations of using large SNP sets versus a few very informative markers as predictors of genetic merit of breeding candidates are evaluated using field data as an example.

Compensatory growth response in pigs, muscle protein turn-over and meat texture: effects of restriction/realimentation period

The present experiment was designed to evaluate the effect of different time spans of ad libitum feeding of pigs prior to slaughter after a period of restricted feeding on performance and texture characteristics of the meat. Te n litters of five pigs (Duroc ✕ Landrace ✕ Large White crosses) were allocated to five feeding treatments (AA, R28A42, R43A27, R52A18 and R60A10) at the age of 70 days. AA-pigs were given ad libitum a concentrate diet from day 70 to slaughter at day 140 (approx. 100 kg live weight). R28A42, R43A27, R52A18 and R60A10 pigs were given food at a restricted level (0·6 of ad libitum) for 28, 43, 52 and 60 days, respectively, followed by ad libitum feeding for 42, 27, 18 and 10 days, respectively, until slaughter at day 140. All pigs that had been given food at a restricted level for a period (R28A42, R43A27, R52A18 and R60A10) showed a compensatory growth response in the subsequent ad libitum period. However, only pigs on ad libitum for a minimum of 27 days prior to slaughter (R28A42 and R43A27) had carcass weights and muscle mass similar to that of the control pigs (AA) at slaughter. The restricted feeding increased meat proportion, whereas the feeding strategies had no effect on technological meat quality traits (pH24, drip loss and CIE-colour traits: L*, a* and b*). During compensatory growth, protein turn-over was increased and positively related to the length of the ad libitum period as indicated by the concentration of elongation factor-2 (eEF-2) (P < 0·10), the activity of µ-calpain (P < 0·01) and the myofibrillar fragmentation index (MFI) 1 day post mortem in m. longissimus dorsi (P < 0·08) and the solubility of collagen (P < 0·01). Although not significant, the shear force at day 1 followed the same pattern of improvement as the MFI. The concentration of eEF-2 increased at a faster rate following transition to ad libitum feeding than did the activity of µ-calpain. This suggests that muscle protein synthesis increases at a faster rate after change to ad libitum feeding and reaches the same level as in the control pigs (AA) before muscle protein degradation. This time lag between the increase in protein synthesis and degradation could explain the compensatory growth response and it also suggests that in order to use the compensatory growth mechanism to improve tenderness, the optimal time of slaughter may not coincide with the period of highest growth rates, but may occur at a later stage, when muscle protein degradation is maximal. For pigs slaughtered at 100 kg live weight, we expect muscle protein degradation to be maximal some time beyond 42 days of ad libitum feeding prior to slaughter.

Influence of growth rate and muscle type on muscle fibre type characteristics, protein synthesis capacity and activity of the calpain system in Friesian calves

The objective of this study was to determine the effect of growth rate on muscle fibre characteristics, concentration of nucleic acids (RNA and DNA) as indicators of muscle protein synthesis capacity and activity of the calpain system at time of slaughter in m. longissimus lumborum (LL) and m. supraspinatus (SS) from calves, in order to elucidate the effect of growth rate on muscle protein turn-over at time of slaughter. Twenty-four Friesian heifer calves were allocated to two different feeding regimens that allowed for a moderate/moderate (MM) or high/high (HH) growth rate from 5 days of age to 90 kg body weight (BW) (period I) and from 90 kg BW to slaughter at 250 kg BW (period II), respectively. The growth rates in the two periods and the weight of LL and SS at slaughter were recorded. Within 30 min after exsanguination, samples were removed from LL and SS, snap-frozen, and later analysed for muscle fibre type frequency and cross-sectional area, DNA and RNA concentration and the activity of the calpain system. High growth rate (i.e. 895 g/day and 1204 g/day in periods I and II, respectively), compared with moderate growth rate (678 g/day and 770 g/day in periods I and II, respectively) had a marked effect on muscle weight and muscle characteristics. High compared with moderate growth rate resulted in hypertrophic growth of type I, IIA and IIB fibres in LL and of type IIA and type IIB fibres in SS, but had no effect on the muscle fibre type frequency in either of the muscles. High growth rate increased total DNA and RNA content and the RNA: DNA ratio in LL, indicating a greater potential for protein synthesis in this muscle, whereas the effect of growth rate was smaller in SS. The activity of µ-calpain, m-calpain and calpastatin was higher in the red SS muscle compared with the whiter LL muscle. However, these enzyme activities were not affected by growth rate, and thus, did not indicate a higher myofibrillar proteolysis in vivo in calves exhibiting high growth rate compared with moderate growth rate. Overall the results showed that different types of muscles react differently to high versus moderate growth rate. High growth rate induced muscle hypertrophy and increased protein synthesis capacity especially in LL and less in SS, but the activities of the enzymes in the calpain system did not show any concomitant increase in muscle protein degradation that would be in favour of improved meat tenderness.

Exogenous genistein in late gestation: effects on fetal development and sow and piglet performance

Due to their functional similarity to estradiol, phytoestrogens could prove to be beneficial in late gestating sows. The goal of this study was to determine the impact of providing the phytoestrogen genistein during late pregnancy on the performance of sows and their litters. In total, 56 gilts were equally divided into the two following groups on day 90 of gestation: (1) controls (CTL); and (2) two daily i.m. injections of 220 mg of genistein (GEN). Treatments were carried out until farrowing. Jugular blood samples were collected from 16 gilts/treatment on days 89 and 110 of gestation, and on days 3 and 21 of lactation. Milk samples were also obtained from those sows on day 3 of lactation. A male piglet from 16 CTL and 15 GEN litters was slaughtered at 24 h postpartum and a blood sample was obtained. The liver, heart and visceral organs were weighed and the semitendinosus (ST) muscle was collected and carcass composition was determined. The treatment increased (P0.1) on weight or backfat loss of sows during lactation, milk composition or weights of piglets. The pre-weaning mortality rate of piglets was very low (0.1). However, carcasses from GEN litters contained more fat than those from CTL litters (9.63% v. 8.34%, P0.1). In conclusion, injecting gilts with 440 mg/day of genistein in late gestation increased IGF1 concentrations in gilts and carcass fat in neonatal piglets, but had minimal effect on muscle development of piglets at birth and on the performance of lactating sows and their litters.

Compensatory growth feeding strategy does not overcome negative effects on growth and carcass composition of low birth weight pigs

The aim of this study was to evaluate whether the compensatory growth feeding strategy could be a suitable solution for overcoming the negative effects on growth, carcass composition and meat quality of low birth weight pigs. Forty-two Swiss Large White barrows from 21 litters were selected at weaning and categorized into either being light (L; >0.8 and <1.3 kg) or heavy (H; >1.7 kg) birth weight pigs. From 27.8 kg BW, pigs were assigned within birth weight group to one of three feeding groups: AA: ad libitum access to the grower and finisher diet, RR: restricted access to the grower and finisher diet or RA: restricted access to the grower diet and ad libitum access to the finisher diet. At slaughter, the longissimus (LM) and semitendinosus (STM) muscles were removed from the right side of the carcass. Weight, girth and length of the STM and the LM area were determined after muscle excision. Carcass characteristics and meat quality traits were assessed. Using mATPase histochemistry, myofibre size and myofibre type distribution were determined in the LM and STM. Because of longer days on feed, total feed intake was greater (P<0.01) and feed efficiency was lower (P<0.01) in L than H barrows. Regardless of the birth weight group, AA and RA barrows grew faster (P<0.05) than RR barrows. During the compensatory growth period, RA barrows grew faster (P<0.05) than AA or RR barrows. Growth efficiency did not differ between RA and RR barrows but was greater (P<0.05) compared with AA barrows. Carcasses of L barrows were fatter as indicated by the lower (P⩽≤0.05) lean meat and greater (P⩽0.02) omental and subcutaneous fat percentage. Lean meat percentage was lower (P⩽0.05) in AA and RA than RR barrows. These differences caused by ad libitum feed access tended to be greater (feeding regime × birth weight group interaction; P<0.08) in L than H barrows. In L barrows, slow oxidative, fast oxidative glycolytic and overall average myofibre size of the LM and the fast glycolytic myofibres and overall average myofibre size of the dark portion of the STM were larger (P⩽0.03) than in H barrows. The study revealed that the compensatory growth feeding strategy was inadequate in overcoming the disadvantages of low birth weight.

Genetic parameters for haemoglobin levels in pigs and iron content in pork

Genetic parameters were obtained for iron content in m. longissimus dorsi (2255 records) and haemoglobin levels recorded at 5 (4974 records) and 21 (2405 records) weeks of age in two sire lines from September 2009 until January 2011. The measure of iron in pork was the mean of two replicates. Genetic associations of haematological traits with meat quality traits (2255 records), as well as growth rate and backfat (close to 60 000 records), were estimated. Analyses were based on an animal model using residual maximum likelihood procedures. Iron content in pork was moderately heritable (0.34 ± 0.07) and genetic correlations with haemoglobin measures ranged from 0.39 ± 0.24 to 0.58 ± 0.13, indicating their potential use as selection criteria for increasing iron levels in pork. However, heritabilities for haemoglobin levels were low, ranging from 0.04 ± 0.2 to 0.18 ± 0.04. Procedures to measure haemoglobin on farm may require refinement. Redness of pork, quantified by a* value, had high genetic correlations with iron content (0.90 ± 0.04 to 0.94 ± 0.03) and moderate genetic correlations with haemoglobin levels (0.31 ± 0.22 to 0.55 ± 0.15). Iron content had significant genetic associations with L* measures (-0.61 ± 0.14 to -0.54 ± 0.23), b* value (0.60 ± 0.14 for dorsal b* measure, 0.50 ± 0.15 for average of dorsal and ventral b* measures) and pH at 45 min post mortem (-0.42 ± 0.14). These high genetic correlations between colour measurements and iron content in pork provide further avenues for selection strategies to improve iron content in pork. Current selection practices are not expected to affect iron content in pork, as no significant genetic correlations between performance and haematological traits were found.

Effect of breed on performance and meat quality of first parity sows in a seasonal organic rearing system

BACKGROUND

The objective was to compare the performance and meat quality of two different pig breeds: the modern crossbred Landrace × Yorkshire (LY) and the traditional Danish Black-Spotted (BS) breed. The LY gilts and four of the BS gilts were inseminated with semen from Duroc (D) boars; the remaining BS gilts were served by BS boars. The experiment was performed on 26 gilts over 2 years.

RESULTS

The BS breed in general had smaller litter sizes and weaned on average in terms of kg piglet 35% less than the modern breed combination. Crossbred piglets of BS × D had growth rates from birth to weaning comparable with piglets of LY × D. BS first parity sows were significantly fatter and less meaty, and the meat was significantly redder and darker compared to LY. The sensory profiling revealed increased sweetness, crumbliness and tenderness in BS. Further, the fat of the BS breed seemed to be characterized by a special nutty taste.

CONCLUSION

The traditional breed has lower productivity and thereby higher costs of production compared to the modern genotypes. On the other hand, the meat and fat of the traditional purebred have special characteristics that might trigger a market premium.

Effects of limited and excess protein intakes of pregnant gilts on carcass quality and cellular properties of skeletal muscle and subcutaneous adipose tissue in fattening pigs

The aim of this study was to investigate whether dietary protein intake of gilts during gestation below (50%) or above (250%) recommendations affects body composition, carcass and meat quality, and properties of skeletal muscle and subcutaneous adipose tissue (SCAT) in offspring at d 83 and 188 of age. German Landrace gilts were fed isoenergetic gestation diets (~13.7 MJ of ME/kg) containing a low (LP, 6.5%; n = 18), an adequate (AP, 12.1%; n = 20), or a high (HP, 30%; n = 16) protein content from mating until farrowing. Within 48 h of birth, offspring were cross-fostered to sows fed a standard diet. On d 83 of age, no effects of the LP diet on BW and body composition were detected, whereas HP pigs showed a slight growth delay (P = 0.06) associated with increased relative weights of small intestine (P < 0.01) and brain (P = 0.08), and reduced relative thymus weight (P < 0.01). On d 188 of age, BW was not different among the dietary groups. However, the carcass of LP pigs contained less (P = 0.01) lean and more (P = 0.07) fat compared with AP and HP pigs, which was only pronounced in pigs originating from large litters (P < 0.05). Like skeletal muscles (P = 0.06), the heart muscle weighed less (P = 0.02) in LP than AP pigs. Compared with AP pigs, LP pigs exhibited a fewer (P = 0.09) total number of myofibers in semitendinosus muscle plus LM both at d 83 and 188 of age, whereas total muscular DNA was less (P = 0.02) at d 188 only. The mRNA abundance of IGF2 measured on d 188 was reduced in SCAT (P = 0.03) and LM (P = 0.07) of LP compared with AP pigs. No changes in muscular fiber type frequency, capillary density, or creatine kinase activity, as well as SCAT adipocyte size and number, were observed at either stages of age. Meat quality characteristics remained unchanged at d 83, whereas Warner-Bratzler shear force value in LM was decreased (P = 0.03) in LP compared with AP pigs on d 188 of age. The results suggest that the maternal LP diet impairs prenatal myofiber formation, reduces the potential of postnatal lean growth related to reduced IGF2 mRNA expression and myonuclear accumulation, and consequently changes carcass quality toward reduced lean proportion and improved tenderness at market weight. In contrast, except for a slight transient growth delay, excess dietary protein during gestation seems to have little effect on the fetal programming of postnatal muscle and adipose tissue phenotype of the progeny.

Limited and excess protein intake of pregnant gilts differently affects body composition and cellularity of skeletal muscle and subcutaneous adipose tissue of newborn and weanling piglets

AIM

This study investigated whether dietary protein intake less (50%) or greater (250%) than requirements throughout gestation differently affects offspring body composition and cellular properties of skeletal muscle and subcutaneous adipose tissue (SCAT).

METHODS

Primiparous gilts were fed iso-energetic diets containing adequate (22 AP), high (21 HP), or low (19 LP) protein contents. Newborn (n = 166) and weanling piglets cross-fostered to sows fed a standard diet (day 28; n = 83) were examined by morphological, biochemical, histological, and molecular analyses of the body, SCAT, and semitendinosus, longissimus, biceps femoris muscles.

RESULTS

Lowered birth weight (BW) in response to the HP and LP diets (p < 0.01) resulted from decreases in all body constituents in LP, and mainly from reduced body fat in HP piglets (p < 0.05). In the light BW class within litters, HP piglets exhibited a greater percentage of muscle tissue (p < 0.05) than LP piglets. Less SCAT mass in HP and LP piglets resulted from reduced (p < 0.05) number, but not the size of adipocytes. The LP diet adversely affected myogenesis and muscular differentiation derived from less (p < 0.01) primary and secondary myofibers, lower creatine kinase activity (p < 0.05), less IGF2 mRNA (p < 0.10), and greater expression of the embryonic myosin heavy chain isoform (p < 0.01). Catch-up growth of LP but not HP pigs until day 28 increased body fat (p = 0.01). Despite compensated muscle growth in LP piglets, the deficit in myofiber number remained.

CONCLUSION

Poor intrauterine environment by limited and excess protein supply retards fetal growth, but only limited protein supply impairs myogenesis, persistently restricts muscle growth potential, and favors obesity at infancy.

Genes with expression levels correlating to drip loss prove association of their polymorphism with water holding capacity of pork

Six genes that were known to exhibit expression levels that are correlated to drip loss BVES, SLC3A2, ZDHHC5, CS, COQ9, and EGFR have been for candidate gene analysis. Based on in silico analysis SNPs were detected, confirmed by sequencing, and used for genotyping. The SNPs were genotyped in about 1,800 animals from six pig populations including commercial herds of Pietrain (PI) and German Landrace (DL), different commercial herds of Pietrain×(German Large White×German Landrace) (PIF1(a/b/c)), and one experimental F2-population Duroc×Pietrain (DUPI). Comparative and genetic mapping established the location of BVES on SSC1, of SLC3A2 and ZDHHC5 on SSC2, of CS on SSC5, of COQ9 on SSC6 and of EGFR on SSC9, respectively, coinciding with QTL regions for carcass and meat quality traits. BVES, SLC3A2, and CS revealed association at least with drip loss and with several other measures of water holding capacity (WHC). Moreover, COQ9 and EGFR were associated with several meat quality traits such as meat color and/or thawing loss. This study reveals statistic evidence in addition to the functional relationship of these genes to WHC previously evidenced by expression analysis. This study reveals positional and genetic statistical evidence for a link of genetic variation at these loci or close to them and promotes those six candidate genes as functional and/or positional candidate genes for meat quality traits.

Quantitative trait loci for meat quality traits in pigs considering imprinting and epistatic effects

The aim of the research was to gain a better understanding of the genomic regulation of meat quality by investigating individual and epistatic QTL in a three-generation full-sib population (Pietrain x crossbred dam line). In total, 386 animals were genotyped for 96 markers. Analysed traits included pH, reflectance value, conductivity, and meat colour. Thirteen significant individual QTL were identified. The most significant QTL were detected on SSC1 and SSC9 for pH, on SSC4 for meat colour, and on SSC8 for conductivity, accounting for 3.4% to 4.7% of the phenotypic variance. Nine significant epistatic QTL pairs were detected accounting for between 5.7% and 10.9% of the phenotypic variance. Epistatic QTL pairs showing the largest effects were for reflectance value between two locations of SSC4, and for pH between SSC10 and SSC13, explaining 9.5% and 10.9% of the phenotypic variance, respectively. This study indicates that meat quality traits are influenced by numerous QTL as well as a complex network of interactions.

Increased fat mass, decreased myofiber size, and a shift to glycolytic muscle metabolism in adolescent male transgenic mice overexpressing IGFBP-2

To elucidate the functional role of insulin-like growth factor (IGF)-binding protein-2 (IGFBP-2) for in vivo skeletal muscle growth and function, skeletal muscle cellularity and metabolism, expression of signal molecules, and body growth and composition were studied in a transgenic mouse model overexpressing IGFBP-2. Postnatal growth rate of transgenic mice was reduced from day 21 of age by 6-8% compared with nontransgenic controls. At 10 wk of age body lean protein and moisture percentages were lower, whereas fat percentage was higher in IGFBP-2 transgenic mice. Muscle weights were reduced (-13% on day 30 of age, -14% on day 72), which resulted from slower growth of myofibers in size but not from decreases in myofiber number. The reduction in muscle mass was associated with lower total DNA, RNA, and protein contents as well as greater DNA/RNA and protein/RNA ratios. The percentage of proliferating (Ki-67-positive) nuclei within myofibers was reduced (3.4 vs. 5.8%) in 30-day-old transgenic mice. These changes were accompanied by slight reductions in specific p44/42 MAPK activity (-18% on day 72) and, surprisingly, by increased levels of phosphorylated Akt (Ser(473)) (+25% on day 30, +66% on day 72). The proportion of white glycolytic fibers (55.9 vs. 53.5%) and the activity of lactate dehydrogenase (+8%) were elevated in 72-day-old transgenic mice. Most of the differences observed between transgenic and nontransgenic mice were more pronounced in males. The results suggest that IGFBP-2 significantly inhibits postnatal skeletal myofiber growth by decreasing myogenic proliferation and protein accretion and enhances glycolytic muscle metabolism.

Metabolic profiling of heat or anoxic stress in mouse C2C12 myotubes using multinuclear magnetic resonance spectroscopy

In the present study, the metabolic effects of heat and anoxic stress in myotubes from the mouse cell line C2C12 were investigated by using a combination of (13)C, (1)H, and (31)P nuclear magnetic resonance (NMR) spectroscopy and enrichment with [(13)C]-glucose. Both the (13)C and the (1)H NMR spectra showed reduced levels of the amino acids alanine, glutamate, and aspartate after heat or anoxic stress. The decreases were smallest at 42 degrees C, larger at 45 degrees C, and most pronounced after anoxic conditions. In addition, in both the (1)H and the (31)P NMR spectra, decreases in the high-energy phosphate compounds adenosine triphosphate and phosphocreatine with increasing severity of stress were identified. At anoxic conditions, an increase in (13)C-labeled lactate and appearance of glycerol-3-phosphate were observed. Accumulation of lactate and glycerol-3-phosphate is in agreement with a shift to anaerobic metabolism due to inhibition of the aerobic pathway in the mitochondria. Conversely, lower levels of unlabeled ((12)C) lactate were apparent at increasing severity of stress, which indicate that lactate is released from the myotubes to the medium. In conclusion, the metabolites identified in the present study may be useful markers for identifying severity of stress in muscles.

Risk assessment of DFD meat due to pre-slaughter conditions in pigs

A polychotomous logistic regression model was used to identify and assess the risk factors for pork becoming dark, firm and dry meat (DFD). A total of 116 deliveries, comprising 3075 commercial pigs delivered from different farms to five commercial Spanish pig abattoirs were surveyed. The DFD condition was described as an ordinal response variable (normal, moderate and serious) based on measurements of pH(24) in the Semimembranosus muscle. The abattoir, the floor of the lorry, the season, the gender, and the stocking density during transportation influenced the risk of DFD, as well as on-farm fasting time, lairage time and estimated carcass lean content. No effect of the RYR1 gene in the risk of DFD was found. Abattoirs should be especially careful with females slaughtered in winter, where the risk of serious DFD is 4.6% higher than with males slaughtered in summer. The risk of DFD increased with high stocking density and lairage time, and with on-farm fasting times longer than 22h. Our results revealed that lowering the stocking density from 0.37 to 0.50m(2) per 100kg pig during transport would increase the risk of DFD pork by 11%.

Creatine-induced activation of antioxidative defence in myotube cultures revealed by explorative NMR-based metabonomics and proteomics

Background

Creatine is a key intermediate in energy metabolism and supplementation of creatine has been used for increasing muscle mass, strength and endurance. Creatine supplementation has also been reported to trigger the skeletal muscle expression of insulin like growth factor I, to increase the fat-free mass and improve cognition in elderly, and more explorative approaches like transcriptomics has revealed additional information. The aim of the present study was to reveal additional insight into the biochemical effects of creatine supplementation at the protein and metabolite level by integrating the explorative techniques, proteomics and NMR metabonomics, in a systems biology approach.

Methods

Differentiated mouse myotube cultures (C2C12) were exposed to 5 mM creatine monohydrate (CMH) for 24 hours. For proteomics studies, lysed myotubes were analyzed in single 2-DGE gels where the first dimension of protein separation was pI 5-8 and second dimension was a 12.5% Criterion gel. Differentially expressed protein spots of significance were excised from the gel, desalted and identified by peptide mass fingerprinting using MALDI-TOF MS. For NMR metabonomic studies, chloroform/methanol extractions of the myotubes were subjected to one-dimensional ¹H NMR spectroscopy and the intracellular oxidative status of myotubes was assessed by intracellular DCFH₂ oxidation after 24 h pre-incubation with CMH.

Results

The identified differentially expressed proteins included vimentin, malate dehydrogenase, peroxiredoxin, thioredoxin dependent peroxide reductase, and 75 kDa and 78 kDa glucose regulated protein precursors. After CMH exposure, up-regulated proteomic spots correlated positively with the NMR signals from creatine, while down-regulated proteomic spots were negatively correlated with these NMR signals. The identified differentially regulated proteins were related to energy metabolism, glucose regulated stress, cellular structure and the antioxidative defence system. The suggested improvement of the antioxidative defence was confirmed by a reduced intracellular DCFH₂ oxidation with increasing concentrations of CMH in the 24 h pre-incubation medium.

Conclusions

The explorative approach of this study combined with the determination of a decreased intracellular DCFH₂ oxidation revealed an additional stimulation of cellular antioxidative mechanisms when myotubes were exposed to CMH. This may contribute to an increased exercise performance mediated by increased ability to cope with training-induced increases in oxidative stress.

Increased sow nutrition during midgestation affects muscle fiber development and meat quality, with no consequences on growth performance

Pregnant sow nutrition has potential effects on the muscle fiber development of progeny in utero. A total of 199 Landrace x Large White sows from parities 0 to 6 and their offspring were used to evaluate the effects of increasing the feeding amount during midpregnancy on the muscle tissue, growth performance, and meat quality of the progeny. The experiment was divided into 2 study replicates, and in each replicate, sows were assigned to 1 of the 2 treatments: 1) sows in the control group (C sows) were fed 2.5 to 3.0 kg/d (feed: 12.1 MJ of ME/kg and 0.62% lysine) throughout gestation; and 2) sows in the high group (H sows) received an extra feed allowance of 1.5 kg/d for gilts and 2.0 kg/d for multiparous sows above the C amount from d 45 to 85 of gestation (period of secondary muscle fiber formation). Sow backfat was recorded on d 40 and 85 of gestation. Sow performance (litter size and piglet BW) at farrowing and on d 18 of lactation was measured. At weaning, pigs were divided into 5 BW groups/treatment, and progeny growth performance was measured during the nursery (n = 958) and the growing-finishing (n = 636) periods. At slaughter, carcass and meat quality traits (lean content, main cut weight, pH, Minolta color, and drip loss) were recorded from the second lightest group at weaning (BW group 4; n = 90), and samples from the longissimus thoracis muscle were taken to study muscle fiber characteristics (n = 70). The extra nutrition from d 45 to 85 of gestation did not lead to differences in litter size or piglet BW at farrowing and on d 18 of lactation. Pigs born to H mothers had fewer muscle fibers and fewer estimated primary and secondary fibers than did pigs born to C mothers (P < 0.05). However, postnatal growth performance was not consistently affected by the maternal treatment. The smaller number of muscle fibers found in the H group of pigs was associated with fewer type IIB fibers (P < 0.05) with greater cross-sectional areas (P < 0.10), which might be related to the significantly greater meat pH at 24 h postmortem and the smaller L* (lightness) values recorded in the H group of pigs. Results from the present study confirm the existence of effects of maternal nutrition on fetal development, at least in terms of muscle tissue development and meat quality, although with no beneficial effects were found for the postnatal growth performance of the progeny.

The polyacetylenes falcarinol and falcarindiol affect stress responses in myotube cultures in a biphasic manner

The effects of the bioactive polyacetylenes, falcarinol and falcarindiol, present in carrots, celery, celeriac and other umbelliferous vegetables, on the stress responses in primary myotube cultures, were studied. Biphasic responses on cellular stress responses in myotube cultures were investigated by exposing them to various concentrations of falcarinol and falcarindiol for 24 h before testing effects of 100 microM H(2)O(2) on the intracellular formation of reactive oxygen species (ROS), transcription of the antioxidative enzyme cytosolic glutathione peroxidase (cGPx), and the heat shock proteins (HSP) HSP70 and HO1. At low concentrations (1.6 to 25 microM) polyacetylenes caused a slightly accelerated intra-cellular ROS formation, increased cGPx transcription and decreased HSP70 and HO1 transcription. The increased cGPx transcription may be interpreted as an adaptive response to the increased ROS formation and may have caused a reduced demand for the protective functions of the HSPs. ROS formation, however, was substantially decreased after pre-incubation with both polyacetylenes at 50 and 100 microM, the cGPx transcription was reduced and the HSP70 and HO1 transcription increased, indicating a need for the protective and repairing functions of the HSPs. In conclusion, pre-incubation with low concentrations of both polyacetylenes prior to H(2)O(2) exposure induced a cytoprotective effect whereas higher concentrations had adverse effects.

Carcass composition, bone mechanical properties, and meat quality traits in relation to growth rate in rabbits

The objective of this study was to characterize correlated responses in carcass composition, bone mechanical properties, and meat quality indicators to divergent selection for growth rate. Rabbits from low (LOW) or high (HIGH) lines divergently selected over five generations on 63-d BW and a control group (CONT) were used. Rabbits were slaughtered at an average BW of 2,306 +/- 65 g, corresponding to 63, 58, or 52 d of age in LOW (n = 41), CONT (n = 43), and HIGH (n = 44) groups, respectively. Postweaning ADG and G:F increased (P < 0.001) in the order LOW < CONT < HIGH groups. The lengths of the tibia and femur in rabbit legs decreased (P < 0.001) with increasing growth rate. Tibia and femur bone intrinsic stiffness, as assessed by a three-point flexure test, followed the order (P < 0.001) of HIGH < CONT < LOW groups. At the same BW, HIGH rabbits and CONT rabbits showed many similarities for dressing percent, carcass composition, and color and chemical composition of muscles or meat parts. In contrast, carcass yield and the relative proportion of hind part were 3% greater (P < 0.01) in LOW rabbits than in CONT and HIGH rabbits. The meat-to-bone ratio in the hind leg was 11% greater (P < 0.001) in the LOW group compared with the CONT and HIGH groups. Yellow color index and moisture content in LM, a fast-twitch glycolytic muscle, were lower (P < 0.05) in LOW rabbits than in HIGH rabbits, but ultimate pH, WHC, and cooking loss did not differ between the two growth-selected lines. Ultimate pH in semitendinosus, a mixed slow- and fast-twitch oxidoglycolytic muscle, was less (P < 0.001) in HIGH rabbits than in CONT and LOW rabbits. However, lactate dehydrogenase and isocitrate dehydrogenase activities in this muscle (n = 21 per group), assessed at the time of slaughter as markers of glycolytic and oxidative capacities, respectively, did not differ among groups. Growth rate did not modify mean cross-sectional area and type frequency of myofibers in semitendinosus muscle. Finally, Warner-Bratzler shear force and total energy needed to achieve rupture did not differ among groups in semitendinosus muscle (n = 21 per group), whereas they were the least (P < 0.001) in LM (n = 128) from HIGH rabbits. Results from this study indicate that improvement of growth rate by selection has little effect in rabbit carcass and meat quality traits.