Metabolism response of grazing yak to dietary concentrate supplementation in warm season.

Supplementary feeding has a significant effect on the growth performance of grazing yaks. However, as far as is known, little information is available concerning how energy or protein feed supplementation affects the serum metabolome of grazing yaks during the warm season. We investigated the effects of supplementation with two different concentrates on the serum metabolome in grazing yaks using nuclear magnetic resonance spectroscopy in conjunction with multivariate data analysis. Twenty-four 2-year-old female yaks (133.04 ± 6.52 kg BW) were randomly divided into three groups and fed three different regimes (n = 8 per group): (1) grazing plus hull-less barley (HLB) supplementation, (2) grazing plus rapeseed meal (RSM) supplementation, and (3) grazing without supplementation. Both HLB and RSM supplementation significantly increased the average daily gain (ADG), and ADG under HLB supplementation was 11.9% higher (P < 0.05) than that of the RSM group. Supplementation markedly altered glucose, lipid, and protein metabolism, with the difference manifested as increased levels of some amino acids, acetyl-glycoproteins, low-density lipoproteins, and very low-density lipoproteins . Furthermore, the levels of 3-hydroxybutyrate, acetoacetate, and lactate metabolism were decreased. Serum metabolite changes in yaks in the HLB supplementation treatment differed from those in the RSM supplementation treatment; the difference was primarily manifested in lipid- and protein-related metabolites. We conclude that both the energy supplementation (HLB) and the protein supplementation (RSM) could remarkably promote the growth of yak heifers during the warm season, and the effect of energy supplementation was superior. Supplementary feeding changed the serum metabolite levels of yak heifers, indicating that such feeding could improve glucose's energy-supply efficiency and increase the metabolic intensity of lipids and proteins. Supplementation of yaks with HLB was more efficient in the promotion of yak glucose and protein anabolism compared to supplementation with RSM, while having a lesser effect on lipid metabolism.

Effect of different levels of protein concentrates supplementation on the growth performance, plasma amino acids profile and mTOR cascade genes expression in early-weaned yak calves.

OBJECTIVE: This study evaluated the effects of different levels of protein concentrate supplementation on the growth performance of yak calves, and correlated the growth rate to changes occurring in the plasma- amino acids, -insulin profile, and signaling activity of mammalian target of rapamycin (mTOR) cascade to characterize the mechanism through which the protein synthesis can be improved in early weaned yaks. METHODS: For this study, 48 early (3 months old) weaned yak calves were selected, and assigned into four dietary treatments according to randomized complete block design. The four blocks were balanced for body weight and sex. The yaks were either grazed on natural pasture (control diet) in a single herd or the grazing yaks was supplemented with one of the three protein rich supplements containing low (17%; LP), medium (19%; MP), or high (21%; HP) levels of crude proteins for a period of 30 days. RESULTS: Results showed that the average daily gain of calves increased (0.14 vs 0.23-0.26 kg; p<0.05) with protein concentrates supplementation. The concentration of plasma methionine increased (p<0.05; 8.6 vs 10.1-12.4 µmol/L), while those of serine and tyrosine did not change (p>0.05) when the grazing calves were supplemented with protein concentrates. Compared to control diet, the insulin level of calves increased (p<0.05; 1.86 vs 2.16-2.54 µIU/mL) with supplementation of protein concentrates. Addition of protein concentrates up-regulated (p<0.05) expression of mTOR-raptor, mammalian vacuolar protein sorting 34 homolog, the translational regulators eukaryotic translation initiation factor 4E binding protein 1, and S6 kinase 1 genes in both Longissimus dorsi and semitendinosus. In contrast, the expression of sequestosome 1 was down-regulated in the concentrate supplemented calves. CONCLUSION: Our results show that protein supplementation improves the growth performance of early weaned yak calves, and that plasma methionine and insulin concentrations were the key mediator for gene expression and protein deposition in the muscles.

Supplementation dietary zinc levels on growth performance, carcass traits, and intramuscular fat deposition in weaned piglets.

This study was conducted to estimate dietary zinc (Zn) levels on growth performance, carcass traits, and intramuscular fat (IMF) deposition in weaned piglets. Sixty piglets were randomly divided into five groups, as follows: control (basal diet), Zn250, Zn380, Zn570, and Zn760 with supplementation of 250, 380, 570, and 760 mg Zn/kg of the basal diet, respectively. The final weight, average daily gain (ADG), gain/feed (G/F), lean meat percentage, fat meat percentage, lean eye area, backfat thickness, and IMF content were dose-dependently increased in all groups of Zn treatment. The serum total triglycerides (TG) and free fatty acid (FFA) were significantly higher in all Zn treatments than in the control. The enzyme activities of lipoprotein lipase (LPL), fatty acid synthase (FAS), and acetyl-CoA carboxylase (ACC) were markedly higher, while enzyme activities of hormone-sensitive lipase (HSL) and carnitine palmitoyltransferase-1 (CPT-1) were significantly lower in all Zn treatments than in the control. The messenger RNA (mRNA) levels of sterol regulatory element-binding protein 1 (SREBP-1), stearoyl-CoA desaturase (SCD), FAS, ACC, peroxisome proliferator-activated receptor γ (PPARγ), LPL, and adipocyte fatty acid-binding protein (A-FABP) were significantly higher, while the mRNA levels of CPT-1 and HSL were significantly lower in all Zn treatments compared with the control. These results indicated that high levels of Zn increased IMF accumulation by up-regulating intramuscular lipogenic and fatty acid transport gene expression and enzyme activities while down-regulating lipolytic gene expression and enzyme activities.