Effects of altering the ratio of C16:0 and cis-9 C18:1 in rumen bypass fat on growth performance, lipid metabolism, intestinal barrier, cecal microbiota, and inflammation in fattening bulls

Background C16:0 and cis-9 C18:1 may have different effects on animal growth and health due to unique metabolism in vivo.This study was investigated to explore the different effects of altering the ratio of C16:0 and cis-9 C18:1 in fat supplements on growth performance,lipid metabolism,intestinal barrier,cecal microbiota,and inflammation in fattening bulls.Thirty finishing Angus bulls(626±69 kg,21±0.5 months)were divided into 3 treatments according to the randomized block design:(1)control diet without additional fat(CON),(2)CON+2.5%palmitic acid calcium salt(PA,90%C16:0),and(3)CON+2.5%mixed fatty acid calcium salt(MA,60%C16:0+30%cis-9 C18:1).The experiment lasted for 104 d,after which all the bulls were slaughtered and sampled for analysis.Results MA tended to reduce 0–52 d dry matter intake compared to PA(DMI,P=0.052).Compared with CON and MA,PA significantly increased 0–52 d average daily gain(ADG,P=0.027).PA tended to improve the 0–52 d feed conversion rate compared with CON(FCR,P=0.088).Both PA and MA had no significant effect on 52–104 days of DMI,ADG and FCR(P>0.05).PA tended to improve plasma triglycerides compared with MA(P=0.077),significantly increased plasma cholesterol(P=0.002)and tended to improve subcutaneous adipose weight(P=0.066)when compared with CON and MA.Both PA and MA increased visceral adipose weight compared with CON(P=0.021).Only PA increased the colonization of Rikenellaceae,Ruminococcus and Proteobacteria in the cecum,and MA increased Akkermansia abundance(P<0.05).Compared with CON,both PA and MA down-regulated the m RNA expression of Claudin-1 in the jejunum(P<0.001),increased plasma diamine oxidase(DAO,P<0.001)and lipopolysaccharide(LPS,P=0.045).Compared with CON and MA,PA down-regulated the ZO-1 in the jejunum(P<0.001)and increased plasma LPS-binding protein(LBP,P<0.001).Compared with CON,only PA down-regulated the Occludin in the jejunum(P=0.013).Compared with CON,PA and MA significantly up-regulated the expression of TLR-4 and NF-κB in the visceral adipose(P<0.001)and increased plasma IL-6(P<0.001).Compared with CON,only PA up-regulated the TNF-αin the visceral adipose(P=0.01).Compared with CON and MA,PA up-regulated IL-6 in the visceral adipose(P<0.001),increased plasma TNF-α(P<0.001),and reduced the Ig G content in plasma(P=0.035).Compared with CON,PA and MA increased C16:0 in subcutaneous fat and longissimus dorsi muscle(P<0.05),while more C16:0 was also deposited by extension and desaturation into C18:0 and cis-9 C18:1.However,neither PA nor MA affected the content of cis-9 C18:1 in longissimus dorsi muscle compared with CON(P>0.05).Conclusions MA containing 30%cis-9 C18:1 reduced the risk of high C16:0 dietary fat induced subcutaneous fat obesity,adipose tissue and systemic low-grade inflammation by accelerating fatty acid oxidative utilization,improving colonization of Akkermansia,reducing intestinal barrier damage,and down-regulating NF-κB activation.

Effect of changing the proportion of C16:0 and cis-9 C18:1 in fat supplements on rumen fermentation,glucose and lipid metabolism,antioxidation capacity,and visceral fatty acid profile in finishing Angus bulls

This study evaluated the effects of different proportions of palmitic(C16:0)and oleic(cis-9 C18:1)acids in fat supplements on rumen fermentation,glucose(GLU)and lipid metabolism,antioxidant function,and visceral fat fatty acid(FA)composition in Angus bulls.The design of the experiment was a randomized block design with 3 treatments of 10 animals each.A total of 30 finishing Angus bulls(21±0.5 months)with an initial body weight of 626±69 kg were blocked by weight into 10 blocks,with 3 bulls per block.The bulls in each block were randomly assigned to one of three experimental diets:(1)control diet without additional fat(CON),(2)CON+2.5%palmitic calcium salt(PA;90%C16:0),(3)CON+2.5%mixed FA calcium salts(MA;60%C16:0+30%cis-9 C18:1).Both fat supplements increased C18:0 and cis-9 C18:1 in visceral fat(P<0.05)and up-regulated the expression of liver FA transport protein 5(FATP5;P<0.001).PA increased the insulin concentration(P<0.001)and aspartate aminotransferase activity(AST;P=0.030)in bull's blood while reducing the GLU concentration(P=0.009).PA increased the content of triglycerides(TG;P=0.014)in the liver,the content of the C16:0 in visceral fat(P=0.004),and weight gain(P=0.032),and up-regulated the expression of liver diacylglycerol acyltransferase 2(DGAT2;P<0.001)and stearoyl-CoA desaturase 1(SCD1;P<0.05).MA increased plasma superoxide dismutase activity(SOD;P=0.011),reduced the concentration of acetate and total volatile FA(VFA)in rumen fluid(P<0.05),and tended to increase plasma non-esterified FA(NEFA;P=0.069)concentrations.Generally,high C16:0 fat supplementation increased weight gain in Angus bulls and triggered the risk of fatty liver,insulin resistance,and reduced antioxidant function.These adverse effects were alleviated by partially replacing C16:0 with cis-9 C18:1.