23 IMPLICATIONSReview of the available literature indicates that including RAC in the diets of finishing swine improves the rate and efficiency of growth, RAC has no detrimental effects on fresh pork color, firmness, water holding capacity, or marbling or IMF content.Lastly, even though there have been reports that feeding RAC increases pork toughness, the underlying cause may not be RAC per se; the reduction in cooked pork tenderness is probably caused by increased lysine levels in RAC diets.
32 ImplicationsPigs fed ractopamine were more difficult to handle and had elevated heart rates and catecholamine levels after 4 weeks of administration.Pigs that are more difficult to move are more likely to be subjected to rough handling and increased stress during transportation, implying reduced welfare, increased workload for the handlers and, potentially, poorer meat quality.Further research is needed to determine why ractopamine-fed pigs are more difficult to handle and to elucidate ways to ameliorate adverse behavioral responses to handling, in order to prevent widespread reduction in finishing pig well-being and unnecessary costs to the industry.
37 聯合國糧農組織（FAO）與世界衛生組織（WHO）2004年2月4-12日在瑞士日內瓦召開「食品添加物專家聯合會議」第62次JECFA/62/SR結論指出，Ractopamine每日安全攝取量（Acceptable daily intake，簡稱ADI）為0-1μg/kg body weight，其最大殘留限量（Recommended maximum residues limits，簡稱MRLS）如下（單位：μg/kg，即ppb）：聯合國糧農組織（FAO）與世界衛生組織（WHO）2004年2月4-12日在瑞士日內瓦召開「食品添加物專家聯合會議」第62次JECFA/62/SR結論指出，Ractopamine每日安全攝取量（Acceptable daily intake，簡稱ADI）為0-1 μg/kg body weight (60 μg/成人/天)其最大殘留限量（Recommended maximum residues limits，簡稱MRLS）如下品種脂肪腎肝肌肉牛109040豬（單位：μg/kg，即ppb）
45 When the ratio of lean to fat deposition is improved Improved feed conversion efficiencyLower production costsBetter product qualityLess excretion of nitrogenous wastes into the environmentDecreased grazing pressure on fragile landscapesReduced pressure on world feed supplies.However, finding a way to achieve these goals that is reliable, affordable, and acceptable to the majority of consumers has proved to be a major challenge.
46 目標 Hormone (GH and IGF-1) β-agonists myostatin 方法Transgenic animalBreeding
58 鉻Chromium (picolinate, nicotinate, yeast, propionate) Chromium is sometimes considered an essential nutrient, but the requirement is likely so low that it will never be deficient, and no deficiency disease has ever been described.Chromium participates in carbohydrate-metabolism by improving glucose utilization through potentiating the effects of insulin binding to cell receptors.Chromium must be added to the diet in a chelated form to be utilized by the pig. Chromium supplementation (200 ppb) has been proposed to enhance leanness in grow-finish pigs by decreasing backfat and increasing loin eye area (LEA).
59 Corresponding with these slight changes in lean content of grow-finish pigs was a slight improvement in nitrogen digestibility and retention and improved feed efficiency when pigs are fed near their amino acid requirements . When pigs are fed above their nutrient requirements the feed efficiency response to supplemental chromium was very small. Therefore, routine inclusion of chromium in grow-finish diets is situation dependent and may not be profitable in all operations .
60 (A)日增重(B)瘦肉率改善改善Forest plots of the effects obtained in fixed effects models for differences in a) ADG and b) percentage carcass lean when Cr-supplemented (B) and nonsupplemented (A) diets were fed to growing-finishing swine.