Modulation of feed digestibility, nitrogen metabolism, energy utilisation and serum biochemical indices by dietary Ligularia virgaurea supplementation in Tibetan sheep.

Ligularia virgaurea is the most widely functional native herbage in the alpine meadow pastures of the Qinghai-Tibet Plateau (QTP) and has multiple pharmacological and biological activities. The effect of L. virgaurea as a dietary component on the digestion and metabolism of sheep was evaluated by conducting feeding trials in metabolic cages. Thirty-two Tibetan yearling rams (29 ± 1.56 kg BW) were randomly allotted to four groups included in a completely randomised design with eight animals per treatment. Sheep were fed a basal diet (freshly native pasture) without the addition of L. virgaurea (control) or with the addition of L. virgaurea (100, 200, or 300 mg/kg BW per day) for 45 days. Addition of L. virgaurea to the diet of Tibetan sheep was found to influence the average daily gain (quadratic [Q], P < 0.001), feed conversion ratio (Q, P = 0.002), CH4 emissions (linear [L], P = 0.029), DM (Q, P = 0.012), neutral detergent fibre (Q, P = 0.017), acid detergent fibre (ADF) (Q, P = 0.027), and ether extract (EE) intake (Q, P = 0.026). Apparently, different levels of L. virgaurea affected the digestibility coefficients of DM, ADF, and EE (L, P > 0.05; Q, P < 0.05). The nitrogen (N) intake (Q, P = 0.001), retained nitrogen (Q, P < 0.001), and N utilisation efficiency (L, P > 0.05; Q, P ≤ 0.001) were also affected by the dietary inclusion of L. virgaurea. Effects of L. virgaurea feeding were also witnessed on methane energy (CH4-E) (L, P = 0.029), gross energy (GE) (Q, P = 0.013), digestible energy (DE) (Q, P = 0.015), and metabolisable energy (ME) intake (Q, P = 0.015). Energy utilisation efficiency expressed as a proportion of GE intake (DE/GE intake, ME/GE intake, ME/DE intake, FE/GE intake, and CH4-E/GE intake) manifested quadratic changes (P < 0.05) with the increase in the L. virgaurea supplementation level. The addition of L. virgaurea increased the activity of superoxide dismutase (Q, P = 0.026) and glutathione peroxidase activity (Q, P = 0.039) in the serum. Overall, the greatest improvement of feed digestibility, N retention, energy utilisation, and antioxidant capacity of Tibetan sheep was yielded by the inclusion of 200 mg/kg BW per day of L. virgaurea. Therefore, the addition of an appropriate amount of L. virgaurea to the diet of Tibetan sheep is safe and natural, and may enhance the sustainability of small ruminant production systems in QTP areas.

Ecological thresholds of toxic plants for sheep production and ecosystem multifunctionality and their trade-off in an alpine meadow.

Toxic plants are a natural component of alpine meadow which co-evolved with Tibetan sheep for thousands of years. One challenge for indigenous herders is to know the ecological thresholds of toxic plants and maintain their vital functions in ways that are compatible with economic income and ecological conservation. To achieve this, field trials with Tibetan sheep grazing in alpine meadow were conducted to examine the ecological thresholds of toxic plants for sheep production and ecosystem functions and their trade-offs. Our results demonstrated that the changing point values of biomass proportion of toxic plants for dry matter intake and liveweight gain of sheep were 17% and 22%, respectively. The changing point value of biomass (richness) proportion of toxic plants for soil carbon accumulation index was 31% (59%), for soil nutrient cycling index was 38% (42%), and for ecosystem multifunctionality index was 28% (50%). The trade-off between liveweight gain of sheep and ecosystem multifunctionality first decreased and then increased along the gradient of biomass proportion of toxic plants (the value of changing point was 37%), and had a significant negative correlation with richness of toxic plants. In addition, structural equation modeling indicated that toxic plants can affect the trade-off between liveweight gain of sheep and ecosystem multifunctionality though increasing acid detergent fiber of plant and decreasing plant species richness, belowground biomass and soil total phosphorus. Consequently, opinions towards toxic plants should shift from the conventional view that they are serious threat to grassland ecosystem health to an inclusive understanding that they are beneficial to livestock and ecosystem functions under certain ecological thresholds.

Selenium Yeast Dietary Supplement Affects Rumen Bacterial Population Dynamics and Fermentation Parameters of Tibetan Sheep (Ovis aries) in Alpine Meadow.

Selenium (Se) deficiency is a widespread and seasonally chronic phenomenon observed in Tibetan sheep (Ovis aries) traditionally grazed on the Qinghai-Tibet Plateau (QTP). Effects of the dietary addition of Se-enriched yeast (SeY) on the bacterial community in sheep rumen and rumen fermentation were evaluated with the aim of gaining a better understanding of the rumen prokaryotic community. Twenty-four yearling Tibetan rams [initial average body weight (BW) of 31.0 ± 0.64 kg] were randomly divided into four treatment groups, namely, control (CK), low Se (L), medium Se (M), and high Se (H). Each group comprised six rams and was fed a basic diet of fresh forage cut from the alpine meadow, to which SeY was added at prescribed dose rates. This feed trial was conducted for over 35 days. On the final day, rumen fluid was collected using a transesophageal sampler for analyzing rumen pH, NH3-N content, volatile fatty acid (VFA) level, and the rumen microbial community. Our analyses showed that NH3-N, total VFA, and propionate concentrations in the M group were significantly higher than in the other groups (P < 0.05). Both the principal coordinates analysis (PCoA) and the analysis of similarities revealed that the bacterial population structure of rumen differed among the four groups. The predominant rumen bacterial phyla were found to be Bacteroidetes and Firmicutes, and the three dominant genera in all the samples across all treatments were Christensenellaceae R7 group, Rikenellaceae RC9 gut group, and Prevotella 1. The relative abundances of Prevotella 1, Rikenellaceae RC9 gut group, Ruminococcus 2, Lachnospiraceae XPB1014 group, Carnobacterium, and Hafnia-Obesumbacterium were found to differ significantly among the four treatment groups (P < 0.05). Moreover, Tax4fun metagenome estimation revealed that gene functions and metabolic pathways associated with carbohydrate and other amino acids were overexpressed in the rumen microbiota of SeY-supplemented sheep. To conclude, SeY significantly affects the abundance of rumen bacteria and ultimately affects the rumen microbial fermentation.

Selenium supplementation improves nutrient intake and digestibility, and mitigates CH4 emissions from sheep grazed on the mixed pasture of alfalfa and tall fescue.

Low selenium (Se) in soil and forage can adversely affect on the quality of animal-derived foods, and hence on human health. Lambs grazed on mixed pastures of alfalfa (Medicago sativa) and tall fescue (Festuca arundinacea) were supplemented with five levels of Se [0, 3, 6, 9 and 12 µg/kg body weight (BW)]. The intake of dry matter (DM) and organic matter (OM) varied with the level of Se supplementation, with a peak at 6 µg Se per kg BW (p ≤ 0.05). Gross energy (GE) intake, digestive energy (DE) intake and metabolic energy (ME) intake were higher at 6 µg Se per kg BW than at other Se levels (p < 0.01); in addition, methane energy (CH4 -E) output was lower at 6 µg Se per kg BW. Supplementation with Se significantly increased nitrogen (N) intake, faecal N and urine N, for which the peak values were 20.2 g N/, 5.62 g N/day and 7.92 g N/day, respectively, at 6 µg Se per kg BW. Se intake, blood Se, faecal Se, urine Se and retained Se were negatively correlated with forage crude protein (CP) content (p < 0.001) but were positively correlated with the content of neutral detergent fibre (NDF) (p < 0.001) and acid detergent fibre (ADF) (p < 0.001). Thus, we recommend the addition of 6 µg Se per kg BW to sheep grazed on pastures in regions with low soil Se.

Integrated metabolomic and transcriptomic profiling reveals the tissue-specific flavonoid compositions and their biosynthesis pathways in Ziziphora bungeana.

BACKGROUND: Ziziphora bungeana Juz. is a folk medicine from the Xinjiang Uygur Autonomous Region. The herb or the aerial parts of it have been used to medicinally treat cardiovascular diseases. Flavonoids are the main pharmacologically active ingredients in Z. bungeana. Identification of the tissue-specific distribution of flavonoids in Z. bungeana is crucial for effective and sustainable medicinal use of the plant. Furthermore, understanding of the biosynthesis pathways of these flavonoids in Z. bungeana is of great biological significance. METHODS: The flavonoids from different tissues of Z. bungeana were identified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The full-length transcriptome of Z. bungeana was determined using a strategy based on a combination of Illumina and PacBio sequencing techniques. The functions of differentially expressed unigenes were predicted using bioinformatics methods and further investigated by real-time quantitative PCR and phylogenetic relationship analysis. RESULTS: Among the 12 major flavonoid components identified from Z. bungeana extracts, linarin was the most abundant component. Nine flavonoids were identified as characteristic components of specific tissues. Transcriptome profiling and bioinformatic analysis revealed that 18 genes were putatively involved in flavonoid biosynthesis. The gene expression and phylogenetic analysis results indicated that ZbPALs, Zb4CL3, ZbCHS1, and ZbCHI1 may be involved in the biosynthesis of the main flavonoid intermediate. ZbFNSII, ZbANS, and ZbFLS may be involved in the biosynthesis of flavones, anthocyanins, and flavonols, respectively. A map of the biosynthesis pathways of the 12 major flavonoids in Z. bungeana is proposed. CONCLUSIONS: The chemical constituent analysis revealed the compositions of 9 characteristic flavonoids in different tissues of Z. bungeana. Linarin can be hydrolysed into acacetin to exert a pharmaceutical role. Apigenin-7-O-rutinoside is hypothesised to be the precursor of linarin in Z. bungeana. There was greater content of linarin in the aerial parts of the plant than in the whole herb, which provides a theoretical basis for using the aerial parts of Z. bungeana for medicine. These results provide a valuable reference for further research on the flavonoid biosynthesis pathways of Z. bungeana and will be significant for the effective utilisation and ecological protection of Z. bungeana.

Effects of Allium mongolicum Regel supplementation on the digestibility, methane production, and antioxidant capacity of Simmental calves in northwest China.

This study evaluated the effects of Allium mongolicum Regel (AM) supplementation on nitrogen (N) balance, ruminal fermentation, and antioxidant properties. Sixteen male calves were assigned randomly to four groups, and the four were added with 0 (CON), 200 mg/kg (body weight; BW) (Low AM; LA), 400 mg/kg (BW) (Middle AM; MA), or 800 mg/kg (BW) (High AM; HA) per day for each individual. AM was added on dry matter (DM) basis. The experiment lasted for 58 days. Supplementation of AM could significantly increase average daily gain, DM digestibility, acid detergent fiber digestibility, and retained N/Intake N. N digestibility and molar proportion of propionate in the MA and HA treatments were higher than that in the CON treatment (p < .05), respectively. AM supplementation significantly increased the molar concentration of total volatile fatty acid in the rumen fluid (p < .05). The ratio of acetate to propionate in the MA and HA groups was lower than that in the CON treatment (p < .05). Furthermore, AM supplementation significantly reduced methane (CH4 ) (p < .05) emissions. AM supplementation significantly increased the activities of superoxide dismutase. The MA group could significantly increase the activities of glutathione peroxidase and decrease the content of malondialdehyde. Our results indicated that AM supplementation could affect the nutrient digestibility, CH4 emission, and antioxidant capacity of Simmental calves.

Relationship of mineral elements in sheep grazing in the highland agro-ecosystem.

Objective: Minerals are one of the important nutrients for supporting the growth of sheep grazing in the highland, northeast of China. The experiment was conducted to investigate the relationship of both macro and micro minerals in sheep grazing in the highlands of six districts located in the Qilian Mountain of China. Methods: Samples of herbage (n=240) and soil (n=240) were collected at random in a "W" shape across the area designated for harvesting from 24 farms, where the sheep commonly graze in October (winter) for mineral analyses. In addition, serum samples were taken via jugular vein from 20 sheep per farm from 24 farms (n=480 samples in total) for serum minerals analyses. Mean values of macro and micro minerals were statistically compared among districts and the correlations among soil-plant-animal were statistically analyzed and correlations were regressed, as well. Results: The results revealed that there were variations for both macro and micro minerals among districts. Statistical analysis of the correlation coefficients between herbage and sheep were significantly different for most of the minerals but not for P, Cu, and Se. Many correlation regression coefficients were found significantly different among minerals of herbage, soil, and sheep serum especially those of K, Na, Fe, Mn, and Zn (between herbage and sheep serum), and Fe and Mn (between herbage and soil), Na, Fe, Mn, and Zn (between soil and sheep serum), respectively. The regression coefficient equations derived under this experiment for prediction of Ca (R2=0.618), K (R2=0.803), Mg (R2=0.767), Na (R2=0.670), Fe (R2=0.865), Zn (R2=0.950), Mn (R2=0.936), and Se (R2=0.630), resulted in significant R2 values. Conclusion: It is inferred that the winter herbage minerals in all the districts were below the recommended levels for macro minerals which indicated there would be some mineral deficiencies in sheep grazing the herbage in these regions. Supplemental minerals may therefore play an important role in balancing the minerals available from the herbage in winter and would lead to increased productivity in sheep on the highland areas of China. These findings could be potentially applied to the other regions for improving the livestock productivity.