Effects of dietary oil sources and fat extraction methods on apparent and standardized ileal digestibility of fat and fatty acids in growing pigs

Background:There is a lack of data for the standardized ileal digestibility(SID) of fat and fatty acids in national feed databases.In addition,it is important to specify the procedures used for fat analyses.Therefore,an experiment was conducted to 1) determine the apparent ileal digestibility(AID) and SID of fat and fatty acids in ten different oil sources for growing pigs and to develop prediction equations for SID of fat based on fatty acid composition;and 2) compare the effect of the fat extraction methods on the calculated values for endogenous loss and digestibility of fat.Methods:Twenty-two barrows(initial body weight:32.1 ± 2.3 kg) were surgically fitted with a T-cannula in the distal ileum,and allotted to 1 of 11 experimental diets in a 4-period Youden Square design.A fat-free diet was formulated using cornstarch,soy protein isolate and sucrose.Ten oil-added diets were formulated by adding 6% of dietary oil sources to the fat-free diet at the expense of cornstarch.All diets contained 26% sugar beet pulp and 0.40% chromic oxide.Results:The endogenous loss of ether extract(EE) was lower than that of acid-hydrolyzed fat(AEE;P < 0.01).There were significant differences in the AID and SID of fat and saturated fatty acids across the dietary oil sources(P < 0.05).The SID of AEE for palm oil was lower than that of sunflower oil,corn oil,canola oil,rice oil and flaxseed oil(P < 0.01).The AID and SID of fat ranged from 79.65% to 86.97% and from 91.14% to 99.18%.Although the AID of EE was greater than that of AEE(P < 0.01),there was no significant difference in SID of EE and AEE except for palm oil.The ratio of unsaturated to saturated fatty acids(U/S) had a positive correlation with SID of fat(P < 0.05),whereas C16:0 and long chain saturated fatty acids(LSFA) were significant negatively correlated with SID of fat(P < 0.01).The best-fit equation to predict SID of fat was SID AEE = 102.75-0.15 × LSFA-0.74 × C18:0-0.03 × C18:1(Adjusted coefficient of determination = 0.88,P < 0.01).Conclusions:When calculating the SID of fat,the EE content of the samples can be analyzed using the direct extraction method,whereas the acid hydrolysis procedure should be used to determine the AID of fat.Fat digestibility of dietary oils was affected by their fatty acid composition,especially by the contents of C16:0,LSFA and U/S.

Different dietary starch patterns in lowprotein diets:effect on nitrogen efficiency,nutrient metabolism,and intestinal flora in growing pigs

Background:Protein releases amino acids faster than starch releases glucose in digestive tract of pigs fed lowprotein(LP)diets.Poor synchronization of dietary glucose and amino acids supply leads to compromised nitrogen efficiency.Dietary starch patterns modulation may improve this situation.Methods:Growing barrows(29.7±2.0 kg)were randomly allotted into 5 dietary treatments with LP diets consisting of different purified starches.Treatments included:waxy corn starch(W LP),corn starch+waxy corn starch(C+W LP),corn starch(C LP),pea starch+waxy corn starch(P+W LP)and pea starch(P LP).In the experiment,growth performance,protein deposition,nutrient metabolism,and fecal microbial community of pigs were investigated.In vitro starch digestion was used for predicting the in vivo glucose response.Results:Dietary starch in vitro glucose release profile was determined by starch source and the ratio of amylopectin and amylose.C+W LP treatment showed decreased total nitrogen excretion and plasma citrulline concentration and improved plasma leptin concentration among treatments(P<0.05).Besides,the highest nitrogen apparent biological value,whole-body protein deposition and growth performance and lowest urinary nitrogen excretion were also observed in C+W LP treatment.Compared with the other groups,C+W LP and C LP showed increased plasma pyruvate,IGF-1,and lipase concentrations(P<0.05).The W LP group presented dramatically increased plasma alanine and urea nitrogen concentration and decreased aldolase and leptin concentrations(P<0.05).Dietary starch patterns did not make an impact on bacterial richness and diversity,but changed the taxonomic and functional structures of the microbial communities.Microbial protein fermentation product(isobutyrate and isovalerate)presented increased in P LP treatments compared with the other treatments(P<0.05).Conclusions:Dietary starch patterns modulation can regulate dietary glucose release profile,nutrient metabolism,protein turnover,and fecal microbial fermentation in pigs.The optimal dietary glucose release profile effectively strengthened whole-body protein deposition and improve nitrogen efficiency and growth performance in growing pigs fed LP diets.

Effectiveness and safety evaluation of graded levels of N-carbamylglutamate in growing-finishing pigs

The aim of this study was as follows:1)to investigate the effects of graded levels of N-carbamylglutamate(NCG)on performance,blood biochemical indexes,carcass traits and related indicators in growingfinishing pigs,and 2)to determine the optimal supplemental level.The toxicity of high-dose(much higher than recommended levels)NCG was assessed by routine blood tests and blood biochemical and histopathologic examinations of the heart,liver,spleen,lung,kidney and stomach.One hundred and forty-four growing-finishing pigs(DurocLarge WhiteLandrace,32.24±1.03 kg)were used in a 74-d experiment and each treatment was replicated 6 times with 4 pigs(2 barrows and 2 gilts)per replicate.The dietary treatments were a corn-soybean meal basal diet supplemented with 0%(control),0.05%,0.1%,0.15%,0.2%or 1%NCG.The first 5 groups were used to explore the optimal supplemental level of NCG,while the control,0.1%and 1%NCG groups were used to explore the safety of high-dose NCG.Compared with the normal control group,the final body weight and average daily gain tended to be higher in the 0.1%group(P=0.08),the lean percentage tended to be higher in the 0.05%group(P=0.07),the levels of free amino acids in the blood significantly increased in the 0.1%group(P<0.05),both 0.1%and 0.15%NCG supplementation increased the levels of nitric oxide(NO)in serum(P=0.07)and muscle growth-and lipid metabolism-related gene expression(P<0.05)and NCG supplementation improved C18:1N9C monounsaturated fatty acids(MUFA)in a dose-dependent manner(P=0.08).In addition,routine blood tests,blood biochemical indexes and histopathological examination revealed no abnormalities.Overall,increasing the levels of NCG did not linearly improve the above indicators;the 0.1%dose showed the best effect,and a high dose(1%)did not pose a toxicity risk.