Effects Of Chromium Picolinate On Fat Deposition Of Ross Broilers

The study indicates that chromium has positive effects on reducing fat deposition in broilers, but the exact mechanism is unknown.Based on the former research foundations, this study will try to explore the effects of Cr content in respect of apparent and molecular level to identify Cr effect mechanism on fat metabolism in broilers.360 one-day-old Ross broilers chicks with approximate weight were selected and divided randomly into 5 groups with 6 replicates per group and 12 broiler chicks per replicate. The chicks in group Ⅰwere fed the basal diet, groupⅡ-Ⅴ were fed basal diet supplemented with 0.1,0.2,0.4and 0.8mg/kg chromium picolinate( the measurement of the total chromium content) respectively. The experiment lasted for 42 days. The results showed that:Experiment 1: This experiment was conducted to investigate the influence of chromium picolinate on the abdominal fat percentage rule of abdominal fat deposition, subcutaneous fat, intramuscular fat and the relevant serum biochemical parameter of Ross broiler chicks. After the feeding experiment,killed the broilers and collected samples to measure items above.The results showed that:On day 21,the abdominal fat deposition tended to decrease in groupsⅡ-Ⅴ, and group Ⅳdecreased by 44.64%(P<0.05). Subcutaneous fat tended to decrease,but there were no significant differences among the groups(P>0.05).Intramuscular fat had no regular changes. Serum TG contents in Group Ⅱ、Group Ⅲ and Group Ⅳ decreased by17.14%(P<0.05)、14.29%(P<0.05)�'� 15.71%(P<0.05) respectively. Serum HDL-C contents in Group Ⅴ increased significantly by 11.59%(P<0.05).Serum TC and TG contents had no significant differences among other groups.On day 42, the abdominal fat rate of chicks in trial groups decreased by 23.90%(P>0.05)、24.88%(P>0.05)、34.15%(P<0.05) and 29.76%(P<0.05)respectively. The subcutaneous fat thickness of group Ⅳdecreased by 11.76%(P<0.05).Serum TC of group Ⅲ and group Ⅳ decreased by 26.62%(P<0.05) and 25.32%(P<0.05) respectively, which showed tendence to decrease in group Ⅱ and group Ⅴ as well but with little difference(P>0.05). Serum TG of group Ⅲ and group Ⅳdecreased by 23.26% and 22.48%(P<0.05) respectively. Chromium picolinate significantly decreased serum LDL-C(P<0.05) and improved the serum HDL-C of group Ⅱgroup Ⅳ and group Ⅴ(P>0.05)and increased HDL-C of group Ⅲ by 18.36%(P<0.05). It is indicated that chromium picolinate can effectively reduce abdominal fat of Ross broilers and significantly affect abdominal fat deposition, decrease the subcutaneous fat, change the intramuscular fat irregularly and significantly affect serum TC、TG、LDL-C and HDL-C. The experiment showed that the optimum quantity of chromium picolinate is 0.4mg/kg.Expriment 2: This experiment is conducted to study effects of chromium picolinate(CrP) gradients on the mRNA gene expression levels of the key fat metabolism enzymes-FAS and LPL and the enzymatic activity of FAS, LPL, ACC and HSL in broilers.After the feeding experiment,killed the broilers and collected samples to measure items above.All experimental groups showed low FAS enzyme activity along with adding CrP, but the change was not significant(P>0.05); the ACC enzyme activity also reduced dramatically in four experimental groups(P<0.05); the HSL enzyme activity also reduced; the LPL of pectorals and fat showed the lowest enzyme activity in GroupⅣ adding 0.4 ㎎/kg Cr. Expression levels of FAS gene-mRNA increased in the four experimental groups, especially significantly increasing in GroupⅢ and GroupⅣ(P<0.05); LPL gene-mRNA expression levels improved(P<0.05) in all experimental groups except the Group Ⅲ reduced greatly, but GroupⅡincreased by 66.02%(P<0.05)and GroupⅣ by 33.84%(P<0.05). At day 42, the FAS activity tended to increase(P<0.05) in all experimental groups except Group Ⅳ showing dramatically reduced FAS activity(P<0.05); the ACC activity tended to increase(P<0.05)in GroupⅡand Ⅲ while in Group Ⅳ and Ⅴ it reduced slightly(P<0.05); the HSL activity also increased slightly(P<0.05) in Group Ⅱand Ⅳ while it reduced slightly(P<0.05) in Group Ⅲ and Ⅴ; in addition, the LPL activity in pectorales and the fat also increased(P<0.05) in all experimental groups. Compared with the normal control group, mRNA expression levels of FAS reduced significantly(P<0.05) in all experiental groups except Group Ⅲ showing a significant increase(P<0.05) in FAS expression levels; mRNA expression levels in LPL showed a similar change rule: in Group Ⅲ it increased dramatically(P<0.05) and in the rest experimental groups reduced greatly(P<0.05). The enzymatic activity of FAS and ACC in liver and that of LPL in fat and pectorales reduced overall significantly, compared with the HSL activity in fat also reducing. Also, mRNA expression levels showed a significant change in FAS of liver and LPL in fat, but the experimental result didn’t show the correlation between the dosage and effect.Expriment 3:This experiment was conducted to investigate the influence of chromium picolinate(CrP) on IMF content and the expression levels of A-FABP and H-FABP gene-mRNA in broilers. After the feeding experiment,killed the broilers and collected samples to measure items above.The results suggested that: on day 21, IMF content in pectoral muscle of experimental broilers tended to decline( P>0.05), especially a significant reducing in GroupⅤ(P<0.05), compared with the normal control group(GroupⅠ); IMF content in leg muscle of experimental broilers showed a linear decrease(P>0.05) with Cr content increase. At day 42, the IMF content in pectoral and leg muscles both reduced(P>0.05). At day 21, IMF content in pectoral muscle had strong negative correlation with expression levels of A-FABP gene-mRNA; in addition, IMF content in leg muscle had strong negative correlation with expression levels of H-FABP gene-mRNA. At day 42, expression levels of A-FABP and H-FABP gene-mRNA had weak correlation with the entire IMF content in pectoral and leg muscles. At day 21, A-FABP gene was the major candidate gene influencing the IMF content in pectoral muscle while H-FABP gene was the major candidate gene influencing that in leg muscle. At day 42, A-FABP and H-FABP genes had slight effects on the IMF content in pectoral and leg muscles.