Sheep Muscle Research Articles

Maternal nutrition induces gene expression changes in fetal muscle and adipose tissues in sheep.

BackgroundMaternal nutrition during different stages of pregnancy can induce significant changes in the structure, physiology, and metabolism of the offspring. These changes could have important implications on food animal production especially if these perturbations impact muscle and adipose tissue development. Here, we evaluated the impact of different maternal isoenergetic diets, alfalfa haylage (HY; fiber), corn (CN; starch), and dried corn distillers grains (DG; fiber plus protein plus fat), on the transcriptome of fetal muscle and adipose tissues in sheep.ResultsPrepartum diets were associated with notable gene expression changes in fetal tissues. In longissimus dorsi muscle, a total of 224 and 823 genes showed differential expression (FDR ≤0.05) in fetuses derived from DG vs. CN and HY vs. CN maternal diets, respectively. Several of these significant genes affected myogenesis and muscle differentiation. In subcutaneous and perirenal adipose tissues, 745 and 208 genes were differentially expressed (FDR ≤0.05), respectively, between CN and DG diets. Many of these genes are involved in adipogenesis, lipogenesis, and adipose tissue development. Pathway analysis revealed that several GO terms and KEGG pathways were enriched (FDR ≤0.05) with differentially expressed genes associated with tissue and organ development, chromatin biology, and different metabolic processes.ConclusionsThese findings provide evidence that maternal nutrition during pregnancy can alter the programming of fetal muscle and fat tissues in sheep. The ramifications of the observed gene expression changes, in terms of postnatal growth, body composition, and meat quality of the offspring, warrant future investigation.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-1034) contains supplementary material, which is available to authorized users.

Periconceptional undernutrition programs changes in insulin-signaling molecules and microRNAs in skeletal muscle in singleton and twin fetal sheep.

Maternal undernutrition around the time of conception is associated with an increased risk of insulin resistance in adulthood. We determined the effect of maternal undernutrition in the periconceptional period (PCUN, i.e., 60 days prior to 6 days after conception) and the preimplantation period (PIUN, i.e., 0-6 days after conception) on mRNA expression and protein abundance of key insulin-signaling molecules as well as the global microRNA expression in quadriceps muscle of singleton and twin fetal sheep in late gestation. In singleton fetuses, exposure to PCUN resulted in lower protein abundance of PIK3CB (P < 0.01), PRKCZ (P < 0.05), and pPRKCZ (Thr410) (P < 0.05) in skeletal muscle compared to controls. In PIUN singletons, there was a higher protein abundance of IRS1 (P < 0.05), PDPK1 (P < 0.05), and SLC2A4 (P < 0.05) compared to controls. In twins, PCUN resulted in higher protein abundance of IRS1 (P < 0.05), AKT2 (P < 0.05), PDPK1 (P < 0.05), and PRKCZ (P < 0.001), while PIUN also resulted in higher protein abundance of IRS1 (P < 0.05), PRKCZ (P < 0.001), and SLC2A4 (P < 0.05) in fetal muscle compared to controls. There were specific patterns of the types and direction of changes in the expression of 22 microRNAs in skeletal muscle after exposure to PCUN or PIUN and clear differences in these patterns between singleton and twin pregnancies. These findings provide evidence that maternal undernutrition around the time of conception induces changes in the expression of microRNAs, which may play a role in altering the abundance of the key insulin-signaling molecules in skeletal muscle and in the association between PCUN undernutrition and insulin resistance in adult life.

Association between DLK1 and IGF-I gene expression and meat quality in sheep.

The aim of the present study was to detect delta-like 1 ho-molog (DLK1) and insulin-like growth factor-I (IGF-I) gene expression in the longissimus dorsi of Hu sheep at different growth stages and study the association between these genes and meat quality. The diameter and density of muscle fibers and tenderness of the longissimus dorsi were measured. Growth stage, but not sex, significantly affected DLK1 and IGF-I expression. DLK1 and IGF-I expression in the sheep longissimus dorsi gradually increased with growth, but also decreased during some periods. These results suggest that different growth stages significantly affect DLK1 and IGF-I gene expression in sheep muscle tissue. The ex-pression of DLK1 and IGF-I genes were positively and significantly (P < 0.01) correlated with muscle fiber diameter and muscle fiber shear stress, and negatively and significantly (P < 0.01) correlated with muscle fiber density. Muscle fiber diameter was positively and significantly (P < 0.01) correlated with muscle fiber shear stress, and negatively and significantly (P < 0.01) correlated with muscle fiber density. In addition, DLK-1 expression was significantly (P < 0.01) and positively correlated with IGF-I expression.

Effect of vitamin E supplementation on growth performance, carcass characteristics and intramuscular fatty acid composition of Longissimus dorsi muscle in Tan sheep

The beneficial effects on meat quality of adding vitamin E to diets have been extensively studied in cattle and lamb. However, how supplemental vit E affects the performance and meat quality of 'Tan' sheep has not been reported. Thirty-five male lambs of 'Tan' sheep (20-30 d after weaning) with similar body weight were randomly divided into five groups of seven each to receive a basal diet plus five levels of vit E supplementation: 0 (control group, CG), 20, 100, 200, and 2000 IU d-1 lamb-1. The results showed: 1) no differences were observed in animal growth performance between CG and vit E treated groups (VG) (P > 0.05); 2) vit E supplementation levels over 200 IU d-1 lamb1 dramatically suppressed subcutaneous fat deposition and similarly that above 100 IU d-1 lamb-1 considerably reduced drip loss and pH 24 h of Longissimus dorsi (LD) muscle in VG lambs compared to those of CG (P 0.05); 3) although vit E supplementation generally did not affect the fatty acid composition of intramuscular lipids in LD muscle, the percentage of n-6 polyunsaturated fatty acids (PUFA) and the ratio of n-6/n-3 PUFA were significantly enhanced (P < 0.05) and an increasing tendency (P < 0.1) for both total PUFA proportion and the ratio of PUFA/saturated fatty acids (SFA) was also observed in 'Tan' sheep lambs treated with vit E. In conclusion, vit E supplementation of male 'Tan' sheep lambs did not influence growth performance, significantly reduced subcutaneous fat deposition, drip loss, pH 24 h and tended to improve fatty acid profile of LD muscle.

Niacin supplementation induces type II to type I muscle fiber transition in skeletal muscle of sheep

BackgroundIt was recently shown that niacin supplementation counteracts the obesity-induced muscle fiber transition from oxidative type I to glycolytic type II and increases the number of type I fibers in skeletal muscle of obese Zucker rats. These effects were likely mediated by the induction of key regulators of fiber transition, PPARδ (encoded by PPARD), PGC-1α (encoded by PPARGC1A) and PGC-1β (encoded by PPARGC1B), leading to type II to type I fiber transition and upregulation of genes involved in oxidative metabolism. The aim of the present study was to investigate whether niacin administration also influences fiber distribution and the metabolic phenotype of different muscles [M. longissimus dorsi (LD), M. semimembranosus (SM), M. semitendinosus (ST)] in sheep as a model for ruminants. For this purpose, 16 male, 11 wk old Rhoen sheep were randomly allocated to two groups of 8 sheep each administered either no (control group) or 1 g niacin per day (niacin group) for 4 wk.ResultsAfter 4 wk, the percentage number of type I fibers in LD, SM and ST muscles was greater in the niacin group, whereas the percentage number of type II fibers was less in niacin group than in the control group (P < 0.05). The mRNA levels of PPARGC1A, PPARGC1B, and PPARD and the relative mRNA levels of genes involved in mitochondrial fatty acid uptake (CPT1B, SLC25A20), tricarboxylic acid cycle (SDHA), mitochondrial respiratory chain (COX5A, COX6A1), and angiogenesis (VEGFA) in LD, SM and ST muscles were greater (P < 0.05) or tended to be greater (P < 0.15) in the niacin group than in the control group.ConclusionsThe study shows that niacin supplementation induces muscle fiber transition from type II to type I, and thereby an oxidative metabolic phenotype of skeletal muscle in sheep as a model for ruminants. The enhanced capacity of skeletal muscle to utilize fatty acids in ruminants might be particularly useful during metabolic states in which fatty acids are excessively mobilized from adipose tissue, such as during the early lactating period in high producing cows.

Miosite eosinofílica em bovinos abatidos para consumo humano

Miosite eosinofílica é uma condição inflamatória relativamente rara que afeta os músculos estriados de bovinos e ovinos. A lesão é usualmente associada a cistos degenerados de Sarcocystis spp., principalmente S. cruzi embora esse protozoário ocorra associado às miofibras de praticamente qualquer bovino, sem provocar, na grande maioria das vezes, reação inflamatória. Esse artigo relata os achados macro e microscópicos da miosite eosinofílica em três bovinos abatidos para produção de carne para consumo humano. Macroscopicamente, as lesões consistiam de manchas ou linhas amarelo-pálidas, ocasionalmente esverdeadas, de 2-6mm no miocárdio de três bovinos e no músculo masseter de um deles. Microscopicamente, as lesões consistiam de acúmulos inflamatórios granulomatosos circundando um centro constituído por eosinófilos mortos e degenerados e ocasionais fragmentos de Sarcocystis sp. A imuno-histoquímica realizada no miocárdio de um dos bovinos com um anticorpo policlonal anti-Neospora caninum marcou cistos intactos em miofibras normais e fragmentos de cistos em meio a áreas de intensa reação inflamatória. Esse último achado corrobora a opinião dos que apontam Sarcocystis sp. como tendo participação na causa da miosite eosinofílica.

Development of a Taenia ovis transmission model and an assessment of control strategies

The metacestode stage of the tapeworm, Taenia ovis, causes cystic lesions in the skeletal and cardiac muscle of sheep, which can result in the condemnation of the entire carcass. In recent years, Canadian farms have seen a marked increase in the number of condemnations due to T. ovis. Mathematical transmission models provide a useful tool for predicting parasite transmission and for evaluating the efficacy of potential control options. To date, no model has been developed exclusively for T. ovis. In the work described here, a compartmental, deterministic transmission model was developed to better understand the transmission dynamics of T. ovis on Canadian sheep farms. The model was intended to be practical, and represent the transmission of infection burdens in lambs that result in carcass condemnation, or transmission to canids. All transmission parameters were obtained from the literature or, when unavailable, expert opinion. The model incorporated each stage of the parasite lifecycle using the most probable transmission route on Canadian sheep farms; including definitive host (guard dogs), intermediate host (pastured lambs), and environment. Based on literature, the model performed as expected, and provided a reasonable estimate of parasite prevalence in lambs. In addition, modeling allowed the efficacy of potential control options to be evaluated and compared. Model simulations suggested that infection risk in market lambs could be eliminated through the regular treatment of guardian dogs every fifth week with an appropriate cestocide, or through eliminating carcass consumption by guardian dogs.

Variation of amino acid content in Longissimus dorsi and Triceps brachii muscles in Karakul sheep according to age and muscle region

Variation of amino acid content in Longissimus dorsi and Triceps brachii muscles in Karakul sheep according to age and muscle region

Effects of dietary vitamin E on muscle vitamin E and fatty acid content in Aohan fine-wool sheep.

BackgroundIncreasing the polyunsaturated fatty acid (PUFA) content and decreasing the saturated fatty acid (SFA) content of mutton can help to improve its nutritional value for consumers. Several laboratories have evaluated the effects of vitamin E on the fatty acid (FA) composition of muscle in sheep. However, little information is available on wool sheep, even though wool sheep breeds are an important source of mutton, especially in northern China where sheep are extensively farmed. The present study was designed to address the effects of vitamin E on muscle FA composition in male Aohan fine-wool sheep.MethodsForty-two male Aohan fine-wool lambs (5 mo old) with similar initial body weight were randomly divided into seven groups and fed diets supplemented with 0 (control group), 20, 100, 200, 1,000, 2,000, or 2,400 IU/sheep/d vitamin E for 12 mo. Three lambs from each group were slaughtered to measure vitamin E and FA content in the longissimus lumborum (LL) and gluteus medius (GM) muscles.ResultsVitamin E concentrations in the LL and GM increased significantly after 12 mo of vitamin E supplementation (P < 0.05). However, this increase did not occur in a dose-dependent manner because the muscle vitamin E concentration was highest in the 200 IU/sheep/d group. Dietary vitamin E supplementation also caused a significant reduction in SFA content and an increase in monounsaturated FA (MUFA) content in the LL and GM (P < 0.05). All six doses of vitamin E significantly increased cis9 trans11-conjugated linoleic acid (c9t11-CLA) content in the LL compared with the control group (P < 0.05).ConclusionsDietary supplementation with vitamin E increased muscle vitamin E content and improved the nutritional value of mutton by decreasing SFA content and increasing MUFA and c9t11-CLA contents in Aohan fine-wool sheep. These effects were greatest in sheep fed a diet containing 200 IU/sheep/d vitamin E.

Effects of liquorice extract on the pH value, temperature, drip loss, and meat color during aging of Longissimus dorsi muscle in Tan sheep

The experiment was to investigate the effect of liquorice extract (LE) as an antioxidant supplement in sheep diet on meat physical quality. Fifty-four-month-old Tan male sheep were randomly allocated among five dietary groups with LE supplementation at levels of 0mg/kg, 1000mg/kg, 2000mg/kg, 3000mg/kg and 4000mg/kg feed. After 120 days of feeding, the muscle was sampled at slaughter and the samples were conditioned for 0, 2, 4, 6 and 8 days in a chiller (4°C). The results showed that supplementation with LE decreased (P<0.05) temperature, drip loss, metmyoglobin (MetMb) concentration and percentage, whereas it increased (P<0.05) myoglobin (Mb) concentration. As aging progressed after postmortem, temperature, drip loss and Mb concentration decreased (P<0.05), but MetMb concentration and percentage increased (P<0.05). The results demonstrate that LE supplementation can improve the physical quality of fresh meat, and the data suggest the optimal dose is between 3000mg/kg and 4000mg/kg feed.

Effects of cortisol and dexamethasone on insulin signalling pathways in skeletal muscle of the ovine fetus during late gestation.

Before birth, glucocorticoids retard growth, although the extent to which this is mediated by changes in insulin signalling pathways in the skeletal muscle of the fetus is unknown. The current study determined the effects of endogenous and synthetic glucocorticoid exposure on insulin signalling proteins in skeletal muscle of fetal sheep during late gestation. Experimental manipulation of fetal plasma glucocorticoid concentration was achieved by fetal cortisol infusion and maternal dexamethasone treatment. Cortisol infusion significantly increased muscle protein levels of Akt2 and phosphorylated Akt at Ser473, and decreased protein levels of phosphorylated forms of mTOR at Ser2448 and S6K at Thr389. Muscle GLUT4 protein expression was significantly higher in fetuses whose mothers were treated with dexamethasone compared to those treated with saline. There were no significant effects of glucocorticoid exposure on muscle protein abundance of IR-β, IGF-1R, PKCζ, Akt1, calpastatin or muscle glycogen content. The present study demonstrated that components of the insulin signalling pathway in skeletal muscle of the ovine fetus are influenced differentially by naturally occurring and synthetic glucocorticoids. These findings may provide a mechanism by which elevated concentrations of endogenous glucocorticoids retard fetal growth.

Effect of Calpastatin Gene Polymorphism on Lamb Growth and Muscling

Effect of Calpastatin Gene Polymorphism on Lamb Growth and MusclingThe calpain-calpastatin system plays a key role in skeletal muscle growth and development processes. It is known that calpastatin activity correlates highly with muscle growth rate, which implies that skeletal muscle growth is likely to result from reduced protein degradation due to compromised activity of calpains or substantial increase of calpastatin activity. The objective of the present research was to identify polymorphic forms in intron 12 of the ovine calpastatin gene in sheep of synthetic lines BCP and SCP, followed by determination of the correlation between each polymorphic form of CAST gene and chosen traits characterizing lamb growth and muscling. The present study's results suggest that lambs carrying the "b" and "e" alleles and the "ae" genotype could be preferred when selecting for growth rate. The breeding efforts to obtain substantial increases in sheep muscle mass could focus on animals carrying the "ac" genotype. No statistically significant relationship was observed in any of the analysed cases between values of the traits and the CAST genotype. However, a highly significant effect of the study year on the analysed traits was found. The results should be regarded as preliminary. The research should be continued on a larger group of animals to ensure the adequate number of each genotype. The trends mentioned and discussed above may also serve as an indicator showing the future direction of further studies in this area.

Rotator Cuff Muscles Lose Responsiveness to Anabolic Steroids After Tendon Tear and Musculotendinous Retraction

Background: Long-standing rotator cuff tendon tearing is associated with retraction, loss of work capacity, irreversible fatty infiltration, and atrophy of the rotator cuff muscles. Although continuous musculotendinous relengthening can experimentally restore muscular architecture, restoration of atrophy and fatty infiltration is hitherto impossible. Hypothesis: Continuous relengthening with pharmacological stimulation of muscle growth using an anabolic steroid or insulin-like growth factor (IGF) can reverse atrophy and fatty infiltration as well as improve the work capacity of chronically retracted rotator cuff muscles in sheep. Study Design: Controlled laboratory study. Methods: Sixteen weeks after tenotomy of the infraspinatus (ISP) tendon, atrophy and fatty infiltration had developed in the retracted ISP muscle. The musculotendinous unit was continuously relengthened in 14 sheep during 6 weeks: Four sheep were treated without pharmacological stimulation, 4 with intramuscular administration of an anabolic steroid, and 6 with IGF before final repair and rehabilitation (12 weeks). Changes were documented by intraoperative measurements of muscle work capacity, histology, and computed tomography/magnetic resonance imaging. Results: Musculotendinous relengthening by continuous traction resulted in gains of length ranging from 0.7 cm in the IGF group to 1.3 cm in the control group. Fatty infiltration progressed in all groups, and the muscle’s cross-sectional area ranged from 71% to 74% of the contralateral side at sacrifice and did not show any differences between groups in weight, volume, histological composition, or work capability of the muscle. The contralateral muscles in the anabolic steroid group, however, showed significantly higher (mean ± standard deviation) muscle work capacity of 10 ± 0.9 N·m than the contralateral muscles of the control group (6.8 ± 2.4 N·m) (P < .05). This was accompanied by an increased mean muscle fiber area as well as by an unusual gain in the animals’ weight after injection of the anabolic steroid. Conclusion: Subcutaneous continuous relengthening of a chronically retracted musculotendinous unit is feasible and advances the retracted musculotendinous junction toward its original position. This does not change the muscle work capacity. Whereas anabolic steroids have been shown to be effective in preventing classic degenerative muscle changes after tendon tears, neither an anabolic steroid nor IGF contributes to regeneration of the muscle once degenerative changes are established. Clinical Relevance: The findings demonstrate that muscle cells lose reactiveness to an anabolic steroid and IGF once retraction has led to fatty infiltration and atrophy of the muscle. Retraction of the muscle after tendon tears must be avoided by early repair, particularly in an athlete, as no regeneration can be achieved by mechanical or pharmacological means at this time.

Distribution of, and risk factors associated with, sheep carcass condemnations due to Cysticercus ovis infection on Canadian sheep farms

Cysticercus ovis, the intermediate stage of a canine tapeworm, Taenia ovis, produces cystic lesions in the skeletal and cardiac muscle of sheep which, if numerous, will result in the condemnation of an entire carcass. In 2007 and 2008, the number of carcass condemnations due to C. ovis rose dramatically across Canada, suggesting that the prevalence of this infection on sheep farms was increasing. Trace-back of 237 carcasses condemned at Ontario provincially inspected abattoirs, between March 2009 and March 2011, revealed they originated from 133 farms across Canada.A case–control study was performed (n=40 cases, 56 controls) to identify farm-level risk factors associated with carcass condemnations due to C. ovis. Participating farms, located in Alberta, Saskatchewan, Manitoba and Ontario, were asked to answer a short questionnaire which collected information about each farm's geographic location and management practices. A multivariable logistic regression model revealed that farm dogs scavenging deadstock (OR=4.04; 95% CI: 1.16–14.04) and failing to dispose of deadstock (OR=11.78; 95% CI: 2.93–47.40) were significantly associated with condemnations (p≤0.05).

Postnatal expression of myostain (MSTN) and myogenin (MYoG) genes in Hu sheep of China

The study of candidate genes is an important tool to identify genes associated with economic traits. Skeletal muscle development is an important physiological process in meat animals, and it directly affects meat production. The expression of myostain ( MSTN ) and myogenin ( MYoG ) genes in longissimus dorsi, during the early growth stage of Hu sheep, was studied by semi-quantitative Reverse transcription polymerase chain reaction (RT-PCR). The results demonstrate that age and gender were playing a very important role in the expression of sheep muscle. MSTN and MYOG genes showed similar variation pattern for the male and female. The expression level of the MSTN and MYoG genes all showed a positive correlation with live weight, carcass weight and meat percentage, but only showed a significant relationship with meat percentage. MSTN gene showed an extreme significant positive relationship with MYoG . Key words : Sheep, myostain ( MSTN ), myogenin ( MYoG ), gene expression, muscle trait.

Development of a sensitive and robust liquid chromatography coupled with tandem mass spectrometry and a pressurized liquid extraction for the determination of aflatoxins and ochratoxin A in animal derived foods

A liquid chromatography–tandem mass spectrometry (LC–MS/MS) with a pressurized liquid extraction (PLE) was developed for the simultaneous determination of aflatoxins B1, B2, G1, G2, M1 and M2, and ochratoxin A in the muscle, liver, kidney and fat of swine, bovine and sheep, muscle and liver of chicken, muscle and skin of fish, as well as in hen eggs and dairy milk. Samples were extracted with PLE and cleaned-up with solid phase extraction (SPE) on HLB cartridges. The optimum extraction conditions were obtained as a 11ml ASE cell, acetonitrile/hexane as the extraction solvent, 1500psi, 100°C, a 5min static time and a 60% flush volume. A cheaper and widely used SPE column (Oasis HLB) was applied during clean up. The detection and quantification of the 7 mycotoxins were performed by a reversed-phase liquid chromatography coupled with electrospray ionization triple quadrupole mass spectrometry (LC/ESI-MS/MS). The limits of detection defined as CCα varied from 0.07μg/kg to 0.59μg/kg. The recoveries of spiked samples from 0.25μg/kg to 1μg/kg ranged from 68.3% to 105.7% with the relative standard deviations of less than 17.6%. Performances of the whole analytical procedure met the criteria established by the European Commission for mass spectrometric detection.

Effect of maternal under-nutrition in late gestation on muscle and bone development in fetal sheep.

Effect of maternal under-nutrition in late gestation on muscle and bone development in fetal sheep.

Treatment of flaxseed to reduce biohydrogenation of α-linolenic acid by ruminal microbes in sheep and cattle, and increase n-3 fatty acid concentrations in red meat1,2

The objective of the study was to determine if flaxseed treated with a formaldehyde-free process could increase n-3 fatty acid (FA) concentrations in lamb and steer muscle. Twenty-four lambs (initial BW 43.8 ± 4.4 kg) were randomly divided into 4 groups for a 90-d trial. One treatment group (FLX) was fed 136 g/d of nontreated ground flaxseed; another treatment group (FLXT1) was fed 136 g/d of flaxseed treated to protect a-linolenic acid (ALA) from microbial hydrogenation; a third treatment group (FLXT2) was fed 136 g/d of a second treated flaxseed; and a fourth treatment group (CNTL) was fed corn and soybean meal with similar CP and DE levels as the other treatments. Intake of treated flaxseed raised plasma triacylglycerol concentrations of ALA more (P < 0.01) than intake of nontreated flaxseed did, but there was no difference (P = 0.65) in ALA increase between FLXT1 and FLXT2. Intake of treated flaxseed increased (P ≤ 0.05) muscle phospholipid ALA and eicosapentaenoic acid concentrations more than nontreated flaxseed did. There were no differences in muscle phospholipid n-3 concentrations between FLXT1 and FLXT2. Ten yearling steers (initial BW 437 ± 18 kg) were randomly divided into 2 groups. One group was fed ground flaxseed (0.05% of steer BW/d; FLX; n = 5) and a second group was fed treated flaxseed at the same rate (FLXT; n = 5). The 175-d trial was divided into 2 periods: high roughage, low concentrate period followed by high concentrate, low roughage period. Steers were fed rations that were formulated to be isonitrogenous, isocaloric, and isolipidic. There was no difference (P = 0.37) in increase of ALA in blood plasma of FLX and FLXT groups by the end of the first period. However, FLXT had 16% greater (P = 0.003) concentration of ALA in their plasma during the second period. Muscle phospholipid n-3 FA were not greater (P ≥ 0.55) for steers in the FLXT group. Intake of treated flaxseed raised n-3 concentrations in blood and muscle of sheep, and in blood of cattle but did not raise n-3 FA concentrations in muscle of steers. Supplementing the diets of forage-fed lambs with flaxseed treated to reduce hydrogenation of ALA by ruminal microbes can increase concentrations of n-3 FA in the muscle of lambs.

The critical role of myostatin in differentiation of sheep myoblasts

Myostatin [MSTN, also known as growth differentiation factor 8 (GDF8)], is an inhibitor of skeletal muscle growth. Blockade of MSTN function has been reported to result in increased muscle mass in mice. However, its role in myoblast differentiation in farm animals has not been determined. In the present study, we sought to determine the role of MSTN in the differentiation of primary sheep myoblasts. We found that ectopic overexpression of MSTN resulted in lower fusion index in sheep myoblasts, which indicated the repression of myoblast differentiation. This phenotypic change was reversed by shRNA knockdown of the ectopically expressed MSTN in the cells. In contrast, shRNA knockdown of the endogenous MSTN resulted in induction of myogenic differentiation. Additional studies revealed that the induction of differentiation by knocking down the ectopically or endogenously expressed MSTN was accompanied by up-regulation of MyoD and myogenin, and down-regulation of Smad3. Our results demonstrate that MSTN plays critical role in myoblast differentiation in sheep, analogous to that in mice. This study also suggests that shRNA knockdown of MSTN could be a potentially promising approach to improve sheep muscle growth, so as to increase meat productivity.

Effect of lead in water on the absorption of copper, iron, manganese and zinc by sheep (Ovis aries) infected with sheep tapeworm (Moniezia expansa)

The sheep tapeworm (Moniezia expansa) and its host Ovis aries were analyzed by inductively coupled plasma optical emission spectrometry (ICP-OES) for their copper, iron, manganese, zinc and lead levels. Element concentrations in cestode parasites were compared to those in various organs (liver, kidney, and muscle) of sheep. Tapeworms in the small intestine of sheep that were administered 2g of Pb(CH3COO)2 per os daily (7days) had significantly higher lead concentrations than sheep tissues. Cu levels significantly increased after Pb administration in sheep muscle and sheep tapeworms. Contrarily, Zn content significantly decreased in sheep muscle, but significantly increased in sheep tapeworms. However, Mn content significantly decreased after Pb administration in sheep tapeworms. Furthermore, Fe content significantly decreased after Pb administration in sheep liver and kidneys.