| Summary: | 碩士 === 國立嘉義大學 === 動物科學系碩士班 === 93 === The purpose of this study is to investigate the caponization and different form of testosterone implantation effects on growth, carcass characteristics, appearance, lipogenesis, lipid transport and β-oxidation metabolism in male chickens as compared to intact male and female chickens, and to realize the role of different form of testosterone in male chickens. Two trials were conducted in the study and subdivided into four parts. In this study, healthy and uniform male Single Comb White Leghorn chickens were caponized at 12-week-old and selected at 16-week-old for a 10-week feeding experiment. Sixteen each male, caponized (capon) and female chickens were assigned for trial 1, and 16 sham operation chickens (sham) and 64 capons (randomly divided into four treatments), which were implanted with cholesterol (1.62 mm i.d., 3.16 mm o.d., 10.4 ± 0.4 mg), testosterone (TES), 5α-dihydrotestosterone (5α-DHT) and 19-nortestosterone (19-NorT) at 16, 20 and 24-week-old in trial 2. First part of this study was conducted to determine the caponization and testosterone effects on growth, appearance and carcass characteristics. Results showed that caponization increased (P < 0.05) body weight gain, feed efficiency (feed/gain), liver weight, gastrointestinal (GI) tract weight, abdominal fat weight and breast weight, and relative GI weight, relative abdominal fat weight, while decreased (P < 0.05) male secondary sexual characteristics (comb length, height and weight) in capon, while the abdominal fat weight and relative abdominal fat weight showed no differences (P > 0.05) with the female in trial 1. Cholesterol and 19-NorT implantation increased weight gain and feed efficiency as compared to sham (P < 0.05). Different form of testosterone implantation increased comb length and weight as compared to CHOL (P < 0.05), but did not achieve the level as sham (P < 0.05). Different form of testosterone implantation decreased abdominal weight and its relative weight as compared to CHOL (P < 0.05), while 19-NorT implantation showed no differences with sham in trial 2. The 2nd part was to determine the blood lipid, lipoprotein composition and structure in chickens to realize whether the lipid transport was changed after caponization and find out the role of testosterone play. Results from trial 1 showed that caponization decreased testosterone concentration (P < 0.05) in male chickens, while showed no difference with female chickens (P > 0.05), and increased LPL activity and blood CHOL concentration (P < 0.05). Female chickens showed the highest blood E2, TG, PL content and VLDL ration (P < 0.05), but the lowest glucose and HDL ratio (P < 0.05). Caponization increased the LDL content and LDL-PRO percentage (P < 0.05), but decreased the HDL-FC percentage which showed no differences with female chicken (P > 0.05). In trial 2, each testosterone implantation group showed higher blood CHOL concentration than sham (P < 0.05). CHOL implantation increased LPL activity than sham (P < 0.05), and 19-NorT and 5α-DHT implantation showed the lowest LPL activity (P < 0.05). Capon implanted different form of testosterone showed increased LDL and VLDL&LDL ratio, and decreased HDL ratio (P < 0.05) with the identical level as the sham (P < 0.05), but did not decrease LDL and HDL content (P > 0.05). Capon implanted different form of testosterone showed change TG and PRO percentage in LDL, and reached the identical level as sham (P > 0.05). CHOL implantation decreased HDL-FC percentage compared to sham (P < 0.05), but which was not recovered by testosterone implantations (P < 0.05). The 3rd part was to determine the effects on the apolipoprotein (apo) composition within the lipoproteins. Results showed that caponization decreased LDL apo B ratio as compared to the female but increased than the male (P < 0.05), and HDL apo A-I ratio was decreased than male chicken (P < 0.05). The HDL apo ratios were no effected by caponization in male chicken (P < 0.05), but apo 66 kDa, apo A-I, apo C-like, and apo E-like ratio was increased in capon than the female (P < 0.05). In trial 2, CHOL and different form of testosterone implantation increased LDL apo 66 kDa and apo A-II ratio as compared to the sham (P < 0.05), except for the apo 66 kDa ratio in 5α-DHT group reach the identical level as the sham (P > 0.05). CHOL implantation decreased LDL apo A-I ratio as compared to sham (P < 0.05), but this was not found in different form of testosterone groups (P > 0.05). The 4th part was to determine the effects and role of testosterone on liver lipid composition, hepatic lipogenic enzyme activity and β-oxidation enzyme activity. Caponization increased the total liver lipid content and TG percentage with decreased PL percentage as compared to male (P < 0.05). Caponization increased liver saturated fatty acid percentage as compared to male (P < 0.05), and achieved to the level as the female (P > 0.05). Caponization increased the MDH activity as compared to male chicken, but lower than female chickens (P < 0.05). In the hepatic β-oxidation enzyme activity, caponization decreased the ECH and KT activity than the male (P < 0.05), and which were lower than female chicken with decreased ACD activity (P < 0.05). In trial 2, different form of testosterone increased the total liver lipid content as compared to sham (P < 0.05), especial for TES implantation. The hepatic NEFA percentage was decreased by TES implantation as compared to the sham (P < 0.05), and 5α-DHT and 19-NorT implantation showed the lowest TG percentage (P < 0.05) but the highest PL percentage (P < 0.05). Capon implanted CHOL and different form of testosterone showed the increased hepatic MDH activity than the sham (P < 0.05). CHOL implantation decreased the ECH and KT activity compared to sham, but 5α-DHT and 19-NorT implantation reached the identical level as sham in ECH activity (P > 0.05). The KT activity showed no difference among the 19-NorT implantation and sham (P > 0.05). Summarize these results, it appears that caponization decreases blood TES, and decreases the lipogenic inhibitory factor, which lead to the elevated MDH activity and liver lipogenesis, and change the lipoprotein profile and LDL apo B and apo A-I ratio, hence results in the different lipoprotein transport and therefore increases lipid accumulation within periphery tissue. Capon implanted different form of testosterone can not inhibit the hepatic lipogensis, but enhance weight gain or male secondary sexual characteristics, enhance β-oxidation enzyme activity, especial for ECH and KT, and therefore decrease body lipid accumulation.
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