| This study was conducted to investigate the effectiveness of nanometer silicate additive (CAN) to adsorb dietary HCH of growing pigs (Duroc X Landrace X Yorkshine) and approach the protection of CAN against adverse effects of HCH on growth performance, apparent digestibility of nutrients, HCH residues in tissues, endocrine function, immune index and anti-oxidative ability, hepatic function, and so on.A total of 96 two crossbred pigs with an average initial body weight of 25.6 ±1.44 kg were randomly allotted to two supplementation of HCH (0.4 and 0.8 mg/kg) and two levels of CAN (0 and 0.5%) in a 2×2 factorial arrangement of treatments, included four groups (0.4mg/kgHCH, T1; 0.4mg/kgHCH+0.5%CAN, T2; 0.8mg/kgHCH, T3; 0.8mg/kg HCH+0.5%CAN, T4). Each group was fed corn-soybean basal diets and consisted of three pens (replications) of sixteen pigs (sex balanced). The feeding experiment last for eight-three days after seven days of adaptation period. Ten days before ending of the feeding trial, digestion experiment was conducted by the method of total fecal collection. The 24 pigs (sex balanced) were kept in individual pens and given their respective experimental diets. At the end of the feeding trial, two pigs from each pen were randomly selected based on similar body weight and slaughtered. Blood and organ samples were collected and determined for HCH residues in tissues, immune index, serum hormone, antioxidation capacity and biochemical index in serum and liver. The main results as follows:The determination of HCH residues in tissues showed that muscle, fat, liver, renal HCH of the group exposed to 0.4mg/kg HCH were 25.38, 533.3, 99.66, 62.47ng/g, respectively, and the HCH consent was beyond the standards of European Union on foods. When 0.5% CAN was added to basal diet, HCH retentions in fat was reach the international standards (EU standards), which permit HCH residues in muscle, liver and kidney. Muscle, fat, liver, renal HCH of the T3 group were 31.75,.780,136.2,80.77ng/g, respectively. HCH retentions in these organs of T2 decreased by 46.5% (p<0.05), 45.0% (p<0.05), 26.7% (p<0.05), 25.0% (p<0.05), respectively, compared to T1. Thecorresponding contents in T4 decreased by 43.7% (p<0. 05) ? 37.2% (p<0. 05) ? 31.7 (p<0.05). 36.0% (p<0.05). Heart, lung, hair and skin HCH of the Tl group were 3.06^ 5.29^ 223.76 ^ 80.23 ng/g, respectively. HCH retentions in these organs of T2 decreased by 22.2% (p<0.05;K 25.2% (p<0.05)s 47.6%(p<0.05^ 45.2% (p<0.05), respectively, compared to Tl. Heart, lung, hair and skin HCH of the T3 group were 4.53 > 7.42 ^ 286.4^ 102.97ng/g, respectively. HCH retentions in these organs of T4 decreased by 19.7% (p<0.05)>28.1% (p<0.05),34.6% (pO.05^29.5% (p<0.05Respectively, compared to T3. The determination of HCH residues in blood showed that blood and serum HCH of the group exposed to 0.4mg/kg HCH were 88.19 ^ 44.52ng/ml respectively. HCH retentions in these blood and serum of T2 decreased by 41.9% (p<0.05)n 25.1% (p<0.05), respectively, compared to Tl. Blood and serum HCH of the exposed to 0.8mg/kg HCH were 139.K 48.82ng/ml respectively, and HCH retentions in these blood and serum of T4 decreased by 37.4%(p<0.05)^ 19.2% (p<0.05).The results of determination of HCH concentrations in gastrointestinal contents and showed that HCH retentions in distal colon and feces of Tl and T3 increased significantly compared with opposite group with CAN, respectively (p<0.05).The determination of HCH residues in urine show that HCH retentions of Tl and T3 decreased significantly compared with opposite group with CAN, respectively (p<0.05).There were no obvious differences for ADG, F/G, digestibility of dry matter and crude protein EE, Ca, P among four groups (p<0.05), but the HCH had a trend to restrain to growth, which was weakened by addition CAN.The analysis of endocrine function showed that, there were no differences for GH^ T3>E2 among the groups, but HCH led to the trend to decrease T4^FSH^E2 and increase G^ LH. Serum FSH was decreased by 18.9% (p<0.05) in T2 group, compare to Tl group; Serum FSH was decreased by 10.0% (p<0.05) in T4 group, compare to T3 groupThe analysis of antioxidation capacity showed that, the activity of serum CAT, SOD, hepatic SOD, GSH-Px, GR, in liver in T2 were increased significantly(p<0.05), MDA content in serum and liver decreased in T2 respectively compared to those of the Tl (p<0.05). There were no significantly difference about content of GSH and the activity of GST among groups.The results of determination on immune index showed that, relative weight of spleen and thymus in T4 was lower than those of T3 (p<0.05), which the thymus in T2 was lower than those of Tl (p>0.05). There was no difference about igM -. IgA^ IgG^ c3 and c4 among groups (p>0.05). Moreover, there was no effect of HCH and CAN on proliferation of T-lymphocyte (p>0.05).Serum AChE and ALP activities, relative weight of kidney in T2 were lower than Tl(p<0.05); these in T4 were higher than T3(p<0.05). It was found via optical microscope in T3 that the thickness of membrane outside glomerulus was increased, and lacuna between inner layer and outer layer of capsula glomeruli was reduced.The analysis of serum triglyceride and Cholesterol showed that the HCH led to the significant increase of serum triglyceride, and did not affect serum Cholesterol. Compared to Tl group, serum triglyceride at T2 group was decreased by 18.6% (p<0.05); serum triglyceride at T4 was decreased by 9. 0% (p<0.05).The analysis of serum lipophilic vitamin showed that, HCH resulted in the decrease in hepatic Ve and VA, which was restrained by CAN. Serum and hepatic Ve for T2 group were respectively increased by 5.7%(p>0.05) ^P 7.2% (p<0.05), compared to Tl; Serum and hepatic Ve for T4 group were respectively increased by 3.8%(p>0.05) and 5.3% (p<0.05), compared to T3 groups.
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