Background: There is increasing research interest in using short-chain fatty acids(SCFAs) including butyrate as potential alternatives to antibiotic growth promoters in animal production. This study was conducted to e...Background: There is increasing research interest in using short-chain fatty acids(SCFAs) including butyrate as potential alternatives to antibiotic growth promoters in animal production. This study was conducted to evaluate the effects of supplementation of sodium butyrate(SB) in liquid feeds(milk, milk replacer, and the mixture of both)on the growth performance, rumen fermentation, and serum antioxidant capacity and immunoglobins in dairy calves before weaning. Forty healthy female Holstein calves(4-day-old, 40 ± 5 kg of body weight) were housed in individual hutches and randomly allocated to 1 of 4 treatment groups(n = 10 per group) using the RAND function in Excel. The control group was fed no SB(SB0), while the other three groups were supplemented with 15(SB15),30(SB30), or 45(SB45) g/d of SB mixed into liquid feeds offered. The calves were initially fed milk only(days 2 to 20), then a mixture of milk and milk replacer(days 21 to 23), and finally milk replacer only(days 24 to 60).Results: The SB supplementation enhanced growth and improved feed conversion into body weight gain compared with the SB0 group, and the average daily gain increased quadratically with increasing SB supplementation. No significant effect on rumen pH;concentrations of NH_3-N, individual and total VFAs;or acetate:propionate(A:P) ratio was found during the whole experimental period. Serum glutathione peroxidase activity increased linearly with the increased SB supplementation, while the serum concentration of maleic dialdehyde linearly decreased. Serum concentrations of immunoglobulin A, immunoglobulin G, or immunoglobulin M were not affected by the SB supplementation during the whole experimental period.Conclusions: Under the conditions of this study, SB supplementation improved growth performance and antioxidant function in pre-weaned dairy calves. We recommended 45 g/d as the optimal level of SB supplementation mixed into liquid feeds(milk or milk replacer) to improve the growth and antioxidant function of dairy calves before weaning.展开更多
Ultra-high molecular weight polyethylene(UHMWPE,M_(w)>10^(6)g mol^(−1))has been prepared using slurryphase titanium permethylindenyl-phenoxy(PHENI^(*))catalysts.Four strategies have been investigated for improving ...Ultra-high molecular weight polyethylene(UHMWPE,M_(w)>10^(6)g mol^(−1))has been prepared using slurryphase titanium permethylindenyl-phenoxy(PHENI^(*))catalysts.Four strategies have been investigated for improving the melt processability of UHMWPE,which is the chief limiting factor to the applications of this high-performance polymer.1)Active site engineering was used to explore the entanglement density in the resulting polymer,with substantially disentangled PE identified through thermal and rheological characterisation.2)Hydrogen and ZnEt2 were employed as chain transfer agents to modulate the polyethylene molecular weight and distribution(MWD).A sequential reactivity protocol using ZnEt2 was able to produce bimodal UHMWPE with improved processability.3)MWD tuning was further investigated using multisite catalysts,with the reaction conditions and Ti:Zr ratio able to control MWD to essentially arbitrary shapes.The inclusion of low molecular weight fractions into UHMWPE improves the processability without compromising mechanical characteristics.4)Polymer-reinforced composite blends of UHMWPE with either HDPE or LDPE as a highly processable matrix were extruded and explored,with polymer miscibility and mechanical properties studied in detail.展开更多
基金partially supported by the National Natural Science Foundation of China (award number:31802092)the National Key Research and Development Program of China (award numbers:2018YFE0101400 and 2017YFD0500502)+1 种基金the Agriculture Science and Technology Innovation Program (award number:ASTIP-IAS07-1)Beijing Dairy Industry Innovation Team (award number:BAIC06–2020)。
文摘Background: There is increasing research interest in using short-chain fatty acids(SCFAs) including butyrate as potential alternatives to antibiotic growth promoters in animal production. This study was conducted to evaluate the effects of supplementation of sodium butyrate(SB) in liquid feeds(milk, milk replacer, and the mixture of both)on the growth performance, rumen fermentation, and serum antioxidant capacity and immunoglobins in dairy calves before weaning. Forty healthy female Holstein calves(4-day-old, 40 ± 5 kg of body weight) were housed in individual hutches and randomly allocated to 1 of 4 treatment groups(n = 10 per group) using the RAND function in Excel. The control group was fed no SB(SB0), while the other three groups were supplemented with 15(SB15),30(SB30), or 45(SB45) g/d of SB mixed into liquid feeds offered. The calves were initially fed milk only(days 2 to 20), then a mixture of milk and milk replacer(days 21 to 23), and finally milk replacer only(days 24 to 60).Results: The SB supplementation enhanced growth and improved feed conversion into body weight gain compared with the SB0 group, and the average daily gain increased quadratically with increasing SB supplementation. No significant effect on rumen pH;concentrations of NH_3-N, individual and total VFAs;or acetate:propionate(A:P) ratio was found during the whole experimental period. Serum glutathione peroxidase activity increased linearly with the increased SB supplementation, while the serum concentration of maleic dialdehyde linearly decreased. Serum concentrations of immunoglobulin A, immunoglobulin G, or immunoglobulin M were not affected by the SB supplementation during the whole experimental period.Conclusions: Under the conditions of this study, SB supplementation improved growth performance and antioxidant function in pre-weaned dairy calves. We recommended 45 g/d as the optimal level of SB supplementation mixed into liquid feeds(milk or milk replacer) to improve the growth and antioxidant function of dairy calves before weaning.
基金funding from the Engineering and Physical Sciences Research Council Impact Acceleration Account(EP/X525777/1).
文摘Ultra-high molecular weight polyethylene(UHMWPE,M_(w)>10^(6)g mol^(−1))has been prepared using slurryphase titanium permethylindenyl-phenoxy(PHENI^(*))catalysts.Four strategies have been investigated for improving the melt processability of UHMWPE,which is the chief limiting factor to the applications of this high-performance polymer.1)Active site engineering was used to explore the entanglement density in the resulting polymer,with substantially disentangled PE identified through thermal and rheological characterisation.2)Hydrogen and ZnEt2 were employed as chain transfer agents to modulate the polyethylene molecular weight and distribution(MWD).A sequential reactivity protocol using ZnEt2 was able to produce bimodal UHMWPE with improved processability.3)MWD tuning was further investigated using multisite catalysts,with the reaction conditions and Ti:Zr ratio able to control MWD to essentially arbitrary shapes.The inclusion of low molecular weight fractions into UHMWPE improves the processability without compromising mechanical characteristics.4)Polymer-reinforced composite blends of UHMWPE with either HDPE or LDPE as a highly processable matrix were extruded and explored,with polymer miscibility and mechanical properties studied in detail.
