This study aimed to determine the requirements of standardized ileal digestible (SID) methionine (Met) + cysteine (Cys) of 15–30 kg barrows, maintaining or increasing the 1:1 ratio between SID Met and SID Cys. Seventy crossbred barrows averaging 15.2 ± 0.54 kg of live weight were allotted in a randomized block design 2 × 3 + 1 factorial scheme, with five replicates and two animals per pen. Treatments consisted of maintaining or increasing the 1:1 ratio between SID Met and SID Cys, three levels of SID Met + Cys (5.8, 6.4 and 7.0 g/kg) and a basal diet containing the lowest SID Met + Cys level (5.2 g/kg), formulated to provide a 1:1 ratio of SID Met (2.6 g/kg) and SID Cys (2.6 g/kg). Performance, blood parameters, longissimus dorsi muscle depth, backfat thickness and S–S linkages in the bristles were evaluated. The best average daily gain was estimated at 6.61 g/kg of SID Met + Cys, without maintaining the 1:1 ratio between sulphur amino acids (SAA). The daily intake of SID Met + Cys increased due to dietary SID Met + Cys levels, maintaining or increasing the same ratio between SAA. Plasma glucose increased and total cholesterol decreased according to SID Met + Cys levels, without maintaining the same ratio between the SAA. The requirement of SID Met + Cys for 15–30 kg barrows was 6.61 g/kg (7.88 g/day) for an optimum average daily gain, with no need to maintain the same ratio between the SAA.

中文翻译：

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在标准化回肠可消化蛋氨酸和半胱氨酸之间保持相同的比例不会影响其对起始猪的需求

本研究旨在确定 15-30 kg 手推车对标准化回肠可消化 (SID) 蛋氨酸 (Met) + 半胱氨酸 (Cys) 的需求，维持或增加 SID Met 和 SID Cys 之间 1:1 的比例。70 头平均活重为 15.2 ± 0.54 kg 的杂交手推车被分配到随机区组设计 2 × 3 + 1 因子方案中，每栏有 5 次重复和 2 头动物。治疗包括维持或增加 SID Met 和 SID Cys 之间的 1:1 比例、三个水平的 SID Met + Cys（5.8、6.4 和 7.0 g/kg）和含有最低 SID Met + Cys 水平的基础饮食（5.2 g /kg)，配方可提供 1:1 的 SID Met (2.6 g/kg) 和 SID Cys (2.6 g/kg)。性能，血液参数，背最长肌评估了刷毛中的肌肉深度、背膘厚度和 S-S 连接。SID Met + Cys 的最佳平均日增重估计为 6.61 g/kg，而硫氨基酸 (SAA) 之间的比例不保持 1:1。由于膳食 SID Met + Cys 水平，SID Met + Cys 的每日摄入量增加，维持或增加 SAA 之间的相同比率。根据 SID Met + Cys 水平，血浆葡萄糖增加，总胆固醇降低，而 SAA 之间的比率不保持不变。15-30 kg 手推车对 SID Met + Cys 的要求为 6.61 g/kg（7.88 g/天），以获得最佳的平均日增重，无需在 SAA 之间保持相同的比率。