Inferring the Skeletal Muscle Developmental Changes of Grazing and Barn-Fed Goats from Gene Expression Data.

Thirty-six Xiangdong black goats were used to investigate age-related mRNA and protein expression levels of some genes related to skeletal muscle structural proteins, MRFs and MEF2 family, and skeletal muscle fiber type and composition during skeletal muscle growth under grazing (G) and barn-fed (BF) feeding systems. Goats were slaughtered at six time points selected to reflect developmental changes of skeletal muscle during nonrumination (days 0, 7, and 14), transition (day 42), and rumination phases (days 56 and 70). It was observed that the number of type IIx in the longissimus dorsi was increased quickly while numbers of type IIa and IIb decreased slightly, indicating that these genes were coordinated during the rapid growth and development stages of skeletal muscle. No gene expression was affected (P > 0.05) by feeding system except Myf5 and Myf6. Protein expressions of MYOZ3 and MEF2C were affected (P < 0.05) by age, whereas PGC-1α was linearly decreased in the G group, and only MYOZ3 protein was affected (P < 0.001) by feeding system. Moreover, it was found that PGC-1α and MEF2C proteins may interact with each other in promoting muscle growth. The current results indicate that (1) skeletal muscle growth during days 0-70 after birth is mainly myofiber hypertrophy and differentiation, (2) weaning affects the expression of relevant genes of skeletal muscle structural proteins, skeletal muscle growth, and skeletal muscle fiber type and composition, and (3) nutrition or feeding regimen mainly influences the expression of skeletal muscle growth genes.

Effects of three methane mitigation agents on parameters of kinetics of total and hydrogen gas production, ruminal fermentation and hydrogen balance using in vitro technique.

Methane (CH4 ) can be mitigated through directly inhibiting methanogen activity and starving methanogens by hydrogen (H2 ) sink. Three types of mechanism (i.e. bromoethanesulphonate (BES), nitrate and emodin) and doses of CH4 mitigation agents were employed to investigate their pathways of CH4 inhibition. Results indicated that both BES and emodin inhibited CH4 production and altered H2 balance, which could be accompanied by decreased dry matter disappearance (DMD), fractional rate of gH2 formation, volatile fatty acid (VFA) production, ability to produce and use reducing equivalences and molecular H2 , and increased final asymptotic gH2 production, time to the peak of gH2 , discrete lag time of gH2 production and fermentation efficiency. However, emodin decreased gas volume produced by rapidly fermentable components of substrate and the rate of fermentation at early stage of incubation, while BES supplementation inhibited gas volume produced by both rapidly and slowly fermentable components of substrate and the rate of fermentation at middle or late stage of incubation. The nitrate supplementation inhibited CH4 production without affecting VFA profile, because of its dual role as H2 sink and being toxic to methanogens. Nitrate supplementation had more complicated pattern of fermentation, VFA production and profile and H2 balance in comparison to BES and emodin supplementation.

[Accuracy of predicting in vitro ruminal methane production in goats using volatile fatty acids stoichiometric models].

This study was conducted to investigate the accuracy of predicting in vitro ruminal methane (CH4) production using volatile fatty acids (VFA) stoichiometric models [CH4 = 0.5Ace-0.25Pro + 0.5But-0.25Val] (model 1), where CH4, Ace, Pro, But and Val are the production amounts of CH4, acetate, propionate, butyrate and valerate, respectively. Ten common feedstuffs, including four concentrates and six roughages with a wide range of chemical composition were incubated in serum bottles, and VFAs and CH4 production at 72 h were determined. The differences between the predicted and measured CH4 production were quantified using the model accuracy analysis. The results showed that the predicted CH4 production amounts were generally greater than the measured values obtained using the model 1, and the bias, slope and random error were 62.6%, 11.7% and 25.7%, respectively, indicating that fixed error exceeded 70%. By assuming 80% of total hydrogen being used for CH4 synthesis, the VFA stoichiometric model could be re-expressed as [CH4 = 0.8 (0.5Ace-0.25Pro + 0.5But-0.25Val)] (model 2). The root mean square prediction error (rMSPE = 0.18) for model 2 was less than for model 1 (rMSPE = 0.60). In addition, the bias, slope and random error of the model 2 were 2.1%, 5.7%, 92.3%, respectively, indicating that fixed error was less than 10%. In model 1, hydrogen formation resulting from VFA production were assumed to be totally consumed by methanogens for CH4 synthesis, without considering other pathways of hydrogen metabolism, which was the main factor resulting in the higher predicted values than the measured values.

Effect of tea catechins on regulation of antioxidant enzyme expression in H2O2-induced skeletal muscle cells of goat in vitro.

Skeletal muscle cells (SMCs) of goats were stress induced with 1 mM H(2)O(2) in the absence or presence of 0.5, 5, and 50 µg/mL tea catechins (TCs) incubation. Cells were harvested at 48 h postincubation with TCs to investigate the effects of TCs on cell proliferation, cell membrane integrity, antioxidant enzyme activities, and antioxidant enzyme genes and protein expression levels. Results showed that H(2)O(2) induction inhibited cell proliferation with or without TC incubation; moreover, the inhibition effect was enhanced in the presence of TCs (P < 0.001). H(2)O(2)-induced stress increased the lactate dehydrogenase (LDH) activity in the absence or presence of TC incubation, but concentrations of TCs, less than 5 µg/mL, showed protective functions against LDH leakage than in other H(2)O(2)-induced treatments. The catalase (CAT) activity increased when SMCs were stress induced with H(2)O(2) in the absence or presence of TC incubation (P < 0.001). H(2)O(2)-induced stress decreased CuZn superoxide dismutase (CuZn-SOD) and glutathione peroxidase (GPx) activities, whereas this effect was prevented by incubation with TCs in a concentration-dependent manner. H(2)O(2)-induced stress with or without TC incubation had significant effects on mRNA and protein expression levels of CAT, CuZn-SOD, and GPx (P < 0.001). CAT and CuZn-SOD mRNA expression levels were increased by different concentrations of TC incubation, and this tendency was basically consistent with corresponding protein expression levels. The GPx mRNA expression level increased with a low concentration of TCs but decreased with concentrations greater than 5 µg/mL of TCs, whereas GPx protein expression in all TC-incubated groups was lower than in the control treatment. The current findings imply that TCs had an inhibitory effect on cell proliferation and enhanced damage to the cell membrane integrity, but TCs affected antioxidant status in SMCs by modulating antioxidant enzyme activities at mRNA and protein expression levels.

Effects of rice straw particle size on digesta particle size distribution, nitrogen metabolism, blood biochemical parameters, microbial amino acid composition and intestinal amino acid digestibility in goats.

Effects of rice straw particle size and physically effective neutral detergent fiber (peNDF) on particle size distribution of different digestive tract, nitrogen (N) metabolism, blood biochemical parameters, microbial amino acid (AA) composition and intestinal AA digestibility in goats were investigated. A 4 × 4 Latin square design was employed using four mature Liuyang black goats fitted with permanent ruminal, duodenal, and terminal ileal fistulae. During each of the four periods, goats were offered one of four diets that were similar in chemical composition, but varied in particle sizes and peNDF through alteration of the theoretical cut length of rice straw (10, 20, 40 and 80 mm, respectively). Dietary peNDF contents of four diets were 17.4, 20.9, 22.5 and 25.4%, respectively. Results showed that increasing particle size of rice straw and dietary peNDF significantly affected the particle size distributions of digesta in rumen, duodenum and ileum, except feces. However, increasing particle size of rice straw and peNDF did not affected N metabolism in goats, except the increased apparent N digestibility in rumen and large intestine, and the decreased apparent N digestibility in small intestine. Furthermore, increasing particle size of rice straw and peNDF showed little influence on the profile of blood biochemical parameters, microbial AA composition and intestinal AA digestibility in goats.

Determination of endogenous faecal phosphorus loss in goats.

Four black Liuyang wether goats were fed with corn stover and concentrate formulated to contain four levels of dietary phosphorus (P), including 0.129, 0.140, 0.162 and 0.180% of P. In a 4 x 4 Latin square experiment the endogenous faecal P loss was determined by the regression technique and the substitution method. Treatment effects on faecal and urinary P output, apparent P digestibility and P retention, and saliva P secretion were not significant. A linear relationship was observed between apparent faecal digestible P (Y, g/kg DMI) and P intake (X, g/kg DMI), which was described by the equation: Y = 0.4799 X -0.9209, r2 = 0.9869, (p < 0.05). The true P digestibility determined by the regression technique and the substitution method amounted to 48.0 and 48.9%, respectively; the recorded endogenous faecal P losses were 0.92 and 0.93 g/kg DMI, respectively. The study demonstrated the potential of the regression method as well as the substitution method for estimation of true P digestibility and endogenous faecal P losses in goats.