现代化学材料在骨角质遗物保护中的应用

骨角质遗物是重要的文化遗产种类之一,由于其化学组成与结构的特殊性,考古发掘出土后常伴有表面污染、粉化等严重的病害现象,如何保存骨角质遗物本体及其内涵的历史、科技价值,一直是文物保护领域内非常薄弱的研究课题。种类丰富的化学材料有着不同的特性,为了更好地利用现代化学材料保护骨角质遗物,文中梳理和总结了目前在骨角质遗物的污染物清洗、加固、防霉杀菌、封护、修复粘接等保护修复工作中现代化学材料的应用现状,并尝试分析所用保护材料存在的问题,以期为骨角质遗物的保护研究与工作实践提供参考和借鉴。

Different dietary methionine to lysine ratios in the lactation diet:effects on the performance of sows and their offspring and methionine metabolism in lactating sows

Background:Over the last decade,the nutritional requirements of lactating modern genotype sows have increased.The current nutritional recommendations might be unable to meet the needs of increased litter size and milk production,and thus the nutritional requirements need to be re-evaluated.The current study was conducted to investigate the effects of dietary methionine to lysine(Met:Lys)ratios on the performance of and methionine metabolism in lactating sows.Results:During the 1st week of lactation,piglets reared on sows in the 0.37 to 0.57 Met:Lys ratio groups grew faster than those reared on sows in the control group(0.27)(P<0.01).The 0.37-ratio group showed increased levels of GSHPx in plasma during lactation(P<0.01)and decreased concentrations of urea nitrogen in the plasma of sows(P<0.05).Compared with the 0.27-ratio group,the levels of T-AOC and GSH-Px in the plasma and homocysteine in the milk of lactating sows were significantly increased in sows in the 0.47-ratio group(P<0.01).In sows fed a 0.57-ratio diet,the levels of glutathione and taurine in the plasma and milk were improved significantly during lactation.However,the content of TBARS in the blood(P<0.05 at day 7 and P=0.06 at weaning day)was increased(P<0.01).Moreover,there were linear increases in the levels of homocysteine in the blood and milk of sows during the lactation period(P<0.01)with increased dietary Met:Lys ratios in the lactation diet.Conclusions:The current study indicated that increasing the dietary Met:Lys ratio(0.37~0.57)in the lactation diet had no significant effect on the overall performance of sows or the colostrum and milk composition,but it increased piglet mean BW and piglet ADG during the first week of lactation.Increasing dietary methionine levels had no significant effect on antioxidant function in lactation sows,even though it increased levels of GSH and GSH-Px in the plasma of sows during lactation.However,the content of homocysteine in the plasma and milk increased during lactation due to a high level of dietary methionine.

Profiles of muscular amino acids,fatty acids,and metabolites in Shaziling pigs of different ages and relation to meat quality

Pork meat is closely related to physicochemical alterations during growth and development,resulting in differences in nutritional value and meat flavor.This study aimed to evaluate the composition of amino acids,fatty acids,and metabolic profiles in the longissimus thoracis muscle(LM)of Shaziling pigs aged 30,90,150,210,and 300 days.The results showed that the predominant fatty acids identified in the LM of Shaziling pigs were C16:0,C16:1,C18:0,C18:1n9c,and C18:2n6c.An opposite correlation was observed for C18:2n6c and n6/n3 polyunsaturated fatty acids(P<0.05).Alanine,aspartate,glutamate,Dglutamine,and D-glutamate metabolism were the main metabolic pathways for the Shaziling pig meat flavor(P<0.05).Moreover,the correlation coefficients revealed that the contents of anserine,C16:0,C16:1,and C18:1n9c were positively correlated with intramuscular fat and/or p H24hand were negatively correlated with the values of L^(*)(lightness)and b^(*)(yellowness)(P<0.05).In conclusion,age greatly affected the meat quality of Shaziling pigs,and the contents of muscular anserine,C16:0,C16:1,and C18:1n9c might be promising indicators for better meat quality.

Piglet growth performance improved by dietary supplementation of porous or nano particles of zinc oxide may be related to the gut microbiota

Previous studies on porous or nano particles zinc oxide(ZnO)in the piglets have mainly focused on growth performance and intestinal inflammation,but have scarcely explored the efficacy on gut microbiota.In addition,the efficacy of nano particles ZnO,which is related to its product quality,remains undefined.This study aimed to determine the efficacy of dietary 500 mg/kg porous or nano particles ZnO on the growth performance and gut microbiota of the weaned piglets.A total of 128 weaned piglets were randomly assigned to the dietary groups:NC(basal diet),PC(basal diet+3,000 mg/kg conventional ZnO),500HiZ(basal diet+500 mg/kg porous particles ZnO),and 500ZNP(basal diet+500 mg/kg nano particles ZnO).Compared with the NC diet group,both 500HiZ and 500ZNP increased(P<0.05)average daily feed intake(1 to 28 d)and average daily gain(1 to 28 d),and the 500ZNP tended to decrease feed to gain ratio(F:G ratio,1 to 28 d)(P=0.09).Both 500HiZ and 500ZNP decreased crypt depth of the ileum and increased claudin-2 in the duodenum and zonula occludens-1 in the ileum(P<0.05).Moreover,both 500HiZ and 500ZNP decreased IL-1βand tumor necrosis factor-a(TNF-a)in the jejunum and decreased TNF-a and IL-6 in the ileum(P<0.05).Both 500HiZ and 500ZNP increased microbialβ-diversity index in the ileum and microbial a-diversity indices in the colon of piglets(P<0.05).The probiotic genera Coprococcus(500ZNP)and Blautia(500HiZ)were positively correlated with the F:G ratio(1to 28 d)in colon of piglets(P<0.05).In addition,500HiZ promoted mitochondrial fusion protein 1(MFN1)and zinc transporter-1(ZnT-1)in the jejunum(P<0.05),whilst 500ZNP decreased MFN1 in the jejunum and ZnT-1 in the ileum(P<0.05).In summary,both 500HiZ and 500ZNP improved the growth performance of piglets,which is likely via the genera Blautia and Coprococcus,respectively.Both 500HiZ and 500ZNP improved barrier function and inflammation of the intestine,and 500HiZ achieved better efficacy than 500ZNP on intestine mitochondrial functions.

Starch supplementation improves the reproductive performance of sows in different glucose tolerance status

This study was to evaluate the effects of glucose tolerance status,maternal starch supplementation and soybean substitution in diets on the performance of dams and their offspring.Eighty-eight pregnant sows(Landrace x Large White)were selected from an initial total of 120 sows,based on blood glucose test values,and assigned to 4 experimental treatments in a 2×2 factorial design.The factors were glucose tolerance status(glucose intolerant[GIT]vs.normal glucose tolerant[NGT])or dietary treatments(corn starch diet[CS]vs.soybean substitution diet[SSI]).A higher area under the curve(AUC)for post-meal glucose was observed(P<0.05)in the GIT group than in the NGT group on d 109 of gestation.The CS group had a lower value of homeostasis model assessment-insulin resistance than the SS group(P<0.05)on d 109 of gestation.Corn starch supplementation for sows decreased the stillbirth rate(P<0.05),regardless of the sows’glucose tolerance status.The villus height of the jejunum and the villus height to crypt depth ratio of the ileum were greater in normal birth weight piglets from the CS group than from the SS group(P<0.01),and so was the activity of sucrase in the jejunum and ileum(P<0.01).Compared with the SS group,the CS group showed a reduction in pre-weaning mortality rate,an increase in the number of high-birth-weight piglets,and a decrease in the number of low-birth-weight piglets(P<0.05)under GIT status.In conclusion,sows fed CS decreased stillbirth rate and improved insulin resistance,as well as improving the intestinal morphology and digestive enzyme activities of their progeny,regardless of glucose tolerance status.Additionally,the CS group improved birth weight distribution and decreased pre-weaning mortality rate of piglets under GIT status.

Effects of dietary supplementation of nucleotides from late gestation to lactation on the performance and oxidative stress status of sows and their offspring

Increased metabolic burdens in breeding sows,which are induced by elevated systemic oxidative stress,could increase the need for nucleotides to repair lymphocyte DNA damage;however,de novo synthesis of nucleotides may be insufficient to cover this increased need.This study investigated the effects of dietary nucleotides on milk composition,oxidative stress status,and the reproductive and lactational performance of sows.Forty multiparous sows were assigned to 2 dietary treatments(Control group,and 1 g/kg Nucleotides group)based on a randomized complete block design using their BW at 85 d of gestation as a block.Sows from 2 groups were fed a restricted diet during gestation and ad libitum during lactation.The experiment lasted from 85 d of gestation to 21 d of lactation.The reproductive perfor-mance of sows and the growth performance of suckling piglets were measured.Oxidative stress pa-rameters and milk components were also analysed.Data were analyzed using contrasts in the MIXED procedure of SAS.Sows in the Nucleotides group consumed more feed during the first week(P<0.01)and from 1 to 21 d(P<0.05)of lactation than those in Control group.Correspondingly,the litter weight gain of piglets showed a tendency to increase from cross-fostering to 9 d(P=0.09)and from cross-fostering to 20 d(P=0.10)in the Nucleotides group relative to the Control group.Additionally,the Nucleotides group was higher(P<0.01)than the Control group in the concentrations of uridine 5'monophosphate,guanosine 5'monophosphate,inosine 5'monophosphate,adenosine 5'mono-phosphate and total nucleotides in milk.Furthermore,the Nucleotides group was higher(P<0.01)than the Control group in the serum levels of total antioxidant capacity(P<0.01)for sows at 109 d of gestation and glutathione peroxidase for weaning piglets,but lower at the levels of thiobarbituric acid-reactive substances(P<0.05)in serum of weaning piglets.This study indicated that maternal dietary nucleotides could promote piglet growth,probably due to the higher lactational feed intake and higher concentration of nucleotides in the milk of sows,and lower oxidative stress for both sows and piglets.