| This experiment was conducted to study the effects of different ratios of flax oil and palm oil on nutrient digestibility,lipid metabolism-related enzymes and rumen microorganisms in Albas cashmere goats in vitro and in vivo.It provided the theoretical basis for scientific supplementation of fat in diets to improve economic efficiency.This study included four experiments.Experiment 1 and 2 mainly selected the appropriate ratios of linseed oil and palm oil in vitro and cashmere goats were used as ruminal fluid donors to provide a basis for in vivo experiments.The single-factor completely randomized trial design was used in experiment 1.Experiment 1 included six treatment groups with six replicates.The control group(CON)substrate diet did not contain linseed or palm oils.Other five group were treated with different combinations of linseed and palm oils(MIX,W/W=10:0,6:4,5:5,4:6,0:10).Each treatment was cultured in vitro for 24 hours to study the change on lipid metabolism related enzyme,bacteria quantity in rumen culture medium and the nutrient degradation rate of fermentation substrate,and to explore the appropriate proportion of linseed oil to palm oil.On the basis of experiment 1,seven groups were set in the experiment 2 including control group(CON)without linseed or palm oil,and the other six groups with different combinations of linseed and palm oils(MIX,W/W=10:0,9:1,8:2,7:3,6:4,5:5).The ratio of lipid added is 2%of total diets.The research methods and measurement indicators are the same as experiment 1.The experiment 3 and 4 were conducted using 3*3 Latin square design.Twelve healthy eliminated adult goats with similar age were divided into three treatment groups with four goats in each group,including linseed oil group,palm oil group and mixed oil group with a combination of linseed and palm oils in ratio of 6:4.The experiment was conducted for three periods,each period including 7 d pre-feeding period and 21 d formal test period.The ratio of concentrate to rough was 5:5 and the added oil was 2%of the whole diet.The digestive trial was carried out on the last 5 days of each trial period,and the blood and rumen fluid sample were collected on the last 2 days to analyze.The results of experiment 1 showed that the activities of HSL,LPL,ELOVL5 and SCD in the rumen culture fluid in mixed oil and linseed oil groups were higher than those of the CON group and palm oil group(P<0.05),and the mixed oil group was similar to the linseed oil group,especially in the 6:4 mixed oil group.It suggests that the reduction of linseed oil in mixed oil group cannot reduce the rumen lipid hydrolysis,the enzyme activity related to fatty acid desaturation and prolong and mixed oil group was better than the palm oil group.The number of B.proteoclasticum and B.hungatei in all group with lipid were significantly lower than those in CON group(P<0.05),and the numbers of Anaerovibrio lipolytica and R.albus were opposite(P<0.05).The number of B.hungatei was significantly lower in group 6:4 and linseed oil group than group 4:6,palm oil group and palm oil(P<0.05).Dietary supplementation of 2%different ratios of linseed oil and palm oil had no significant effect on the degradation rate of DM,CP,EE,ADF,P and other nutrients(P>0.05),but the addition of oil reduced the degradation rate of NDF.The results of experiment 2 showed that the activity of HSL,ELOVL5,FADS1 and LPL in the linseed oil group and the mixed oil groups were higher than those in the CON group(P<0.05),and the mixed oil group was similar to the linseed oil group.The number of B.proteoclasticum and B.hungatei in each mixed oil group and linseed oil group was significantly lower than that in CON group(P<0.05),and the changes of Anaerovibrio lipolytica and R.albus were opposite.Dietary supplementation of 2%linseed oil or mixed oil did not negatively affect the degradation of DM,EE,ADF,CP,Ca and P(P>0.05),but reduced NDF degradation.The reduction in NDF degradation rate was alleviated in the 6:4 group than the other groups.The results of experiment 3 showed that the activities of LPL,HSL,G6PDH and FADS1 in the rumen fluid of mixed oil group and linseed oil group were significantly higher than those in palm oil group(P<0.05),but there was no significant difference between linseed oil group and mixed oil group.The rumen SCD and ELOVL5 activity of the linseed oil group was significantly higher than palm oil group(P<0.05);and ELOVL5 activity in mixed oil had no difference with the other two groups.The number of B.proteoclasticum in the rumen of the mixed oil group was significantly lower than that of the palm oil group(P<0.05),and it was also lower than that of the linseed oil group.The results of experiment 4 showed that the addition of linseed oil,mixed oil with a combination of linseed oil and palm oil(6:4)significantly reduced the concentrations of TG,CHO and LDL-C in the serum of cashmere goats and increased the concentration of HDL-C compared with palm oil.The activity of HSL and LPL in palm oil and mixed oil group was lower than that in linseed oil group and the lowest in palm oil group.The activity of ELOVL5 in mixed oil group was similar to linseed oil group,and both of them were higher than palm oil group.In the mixed oil group,the activity of FADS1,ACC,PDK4 was significantly higher than that of linseed oil group and palm oil group(P<0.05).The addition of linseed oil,palm oil and mixed oil had no significant effect on the digestibility of DM,CP,EE and P(P>0.05),but the digestibility of NDF and ADF in the mixed oil group was higher than that in the linseed oil group.The reduction of fibrous digestibility resulting from addition of linseed oil was alleviated by mixed oil.In summary,the mixed addition of linseed oil and palm oil in the diet was more effective than linseed oil or palm oil in promoting the metabolism of lipid-related enzymes and the digestion of fibrous substances and the number of hydrogenated bacteria affecting rumen lipid metabolism,and supplementation with a combination of linseed oil and palm oil(6:4)had a better effect among the mixed oil groups. |
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