| 28 Guanzhong dairy bucks, which were healthy and whose weight was close to each other, were chosen and distributed to 4 groups of a randomized block design. There are 7 goats in every group, and the diet is as follows: 1)basal diet (C),2)basal diet plus1%CLA (CLA1),3)basal diet plus 1%CLA (CLA2) and 4)basal diet plus 1%CLA (CLA3). The Pre-experimental period was 2 weeks and the experimental period was 12 weeks. The data of weight and body measurement were got per 2 weeks. Blood and rumen liquid were collected per 4 weeks. Blood and rumen liquid will be collected before feeding for 0h, after feeding for, 2h, 4h, 6h and 8h at the same time on the day after the end of breeding experiment. Then, all goats were slaughtered to determine the effect of feeding different CLA levels on the growth performance, some blood index, rumen liquid pH, slaughter performance and content of fatty acid in tissue. The results showed that:1 Feeding CLA in the diet had no significant effect on the feed intake, the ratio of feed to meat and some growth performance index(body weight, stem length, body height and circumference)(P>0.05).2 There is no significant effects in the content of total cholesterol (TC), low density lipoprotein-cholesterol (LDL-C), high density lipoprotein-cholesterol (HDL-C), Triacylglycerol (TG) and gluose(G) in every stage between feeding CLA and the control group (P>0.05).Blood samples determined for different time at the same day showed that: LDL-C content of plasma after feeding for 2h, 4h, 8h degraded as the increase of CLA level (P<0.05);TG content of plasma increased as the increase of CLA level after for feeding for 4h (P<0.05); G content of plasma in the group of CLA3 and CLA2 were higher(P<0.05) than the group of CLA1 after feeding for 2h and 4h; There is no significant effect of other plasma indexes on the control group and CLA group (P>0.05 ). On different time of the same day, TC and LDL-C content of plasma first decreased and then increased; HDL-C content of plasma decrease slightly; before and after feeding for 2h, TG content of plasma had no change in every group, and increased after feeding for 4h, and decreased after feeding for 6h; G content of plasma of every group was stable in every interval.3 Rumen liquid ranging from 6.64 to 6.94 in every stage of experiment , there was no significant effect in every group(P>0.05).At the same day, pH decreased as the increase of CLA addition at the different time before and after feeding, among the total, the pH of CLA2 level is significantly higher than CLA3 level before feeding for 2h (P<0.05), the control group and CLA1 level is significantly higher than CLA3 group (P<0.05) after 8h of feeding. Meanwhile pH in every group changed regularly at different time, and pH decreased significantly after feeding, and reached lowest for 6h after feeding, and reached original level for 8h after feeding.4 Basal diet plus CLA had no significant effect in other slaughter index (P<0.05) except that carcass depth and chest muscle thickness are significantly higher in CLA1 group (P<0.05).There was no significant difference for carcass cut in every group (P>0.05) except that front leg weight and front leg bone weight in control group are higher than CLA group. The first grade meat weight and the second grade meat weight and the composition of every grade meat weight in every group had no significant difference (P>0.05) except that the third grade meat weight was significantly higher than the CLA3 group (P<0.05).There was no significant differecant for meat quality index in every group (P>0.05).5 The content of CLA cis-9, trans-11, CLA trans-10, cis-12, total CLA and TVA in muscle increased significantly as the increase of CLA level (P<0.05). The content of CLA cis-9,trans-11 for CLA2 group and CLA3 group were respectively 0.5 times and 0.63 times higher than control group; the content of CLAtrans-10,cis-12 in CLA3 group were 1 time higher than control group; the content of TVA in CLA3 group were 1 time higher than control group. There was no significant effect on the content of SFA, MUFA, PUFA and the ratio of SFA:MUFA, SFA:PUFA, SFA:UFA for CLA added to the diet(P>0.05).The content of CLAcis-9, trans-11, CLAtrans-10,cis-12, total CLA, TVA, PUFA and the ratio of SFA:PUFA and SFA:UFA in kidney fat increased significantly as the increase of CLA additon level (P<0.05). The content of adipose CLA cis-9,trans-11 in CLA1 group, CLA2 group and CLA3 group was separately 0.48, 0.98 and 1.69 times higher than control group; the content of CLAcis-12,trans-10 in CLA1 group, CLA2 group and CLA3 group were separately 1.52,2.84 and 5.52 times higher than control group, compared with control ,the content of C18:1 trans-11 in CLA1 group, CLA2 group and CLA3 group.was 0.6, 1.31 and 1.82 times higher .The ratio of CLAcis-9,trans-11:C18:1 trans11 had no significant change in muscle and fat among every group (P>0.05).
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