Jansman A J M, van Diepen H, Siebert D
Wageningen Livestock Research, P.O. Box 338, 6700 AH Wageningen, the Netherlands.
Wageningen Livestock Research, P.O. Box 338, 6700 AH Wageningen, the Netherlands.
Animal. 2025 Oct;19(10):101646. doi: 10.1016/j.animal.2025.101646. Epub 2025 Sep 4.
Use of low CP diets for pigs contributes to an increased sustainability and reduced environmental impact of pig production. To avoid over- or undersupply of protein and essential amino acids, it is important to have more precise information on the requirement for essential amino acids in pigs in different production phases. Isoleucine (Ile) can be regarded as a potential limiting amino acid in diets for weaned piglets of today's genotype. Therefore, the present study investigated the optimal Ile to lysine (Lys) ratio in diets for postweaning piglets in a dose-response study with 384 postweaning piglets with six dietary treatments (T1-T6) with eight replicates (pens) per treatment. Treatments included provision of diets with incremental levels of standardised ileal digestible (SID) Ile by increasing the inclusion of free L-Ile to reach a ratio of SID Ile to Lys of 37, 41, 46, 50, 55 and 60% (range 4.40 to 7.15 g SID Ile per kg of diet). The basal diet mainly consisted of corn, wheat, barley, potato protein, haemoglobin powder and soybean meal (CP: 150 g/kg; Net energy: 10.46 MJ/kg; SID Lys: 12.0 g/kg) and was supposed to be deficient in Ile (4.40 g SID Ile/kg of the diet). Daily feed intake (dFI), body weight gain (BWG) and feed conversion ratio (FCR) were measured over a period of 4 weeks, starting 6 days postweaning. Regression analysis with a broken line model and a quadratic model was applied to derive the optimal ratio of SID Ile relative to SID Lys in low-protein diets for postweaning piglets. The piglets fed the basal diet had significantly lower BWG, dFI and higher FCR (P < 0.05) than animals fed with Ile-supplemented diets. Both dFI and BWG showed a dose-dependent response towards increasing the dietary level of Ile. The optimal ratio of SID Ile to Lys, based on regression analysis with the quadratic model, was estimated at 52.6 and 52.5% for dFI and BWG, respectively. It is concluded that the optimal ratio of SID Ile relative to Lys to optimise dFI and BWG in piglets fed a low protein diet in the postweaning period is 52%.
对猪使用低粗蛋白日粮有助于提高养猪生产的可持续性并减少其对环境的影响。为避免蛋白质和必需氨基酸供应过多或不足，了解不同生产阶段猪对必需氨基酸的需求的更精确信息很重要。异亮氨酸（Ile）可被视为当今基因型断奶仔猪日粮中潜在的限制性氨基酸。因此，本研究通过对384头断奶仔猪进行剂量反应研究，调查了断奶后仔猪日粮中异亮氨酸与赖氨酸（Lys）的最佳比例，该研究设置了六种日粮处理（T1 - T6），每个处理有八个重复（栏）。处理包括通过增加游离L - 异亮氨酸的添加量来提供标准化回肠可消化（SID）异亮氨酸水平递增的日粮，以使SID异亮氨酸与赖氨酸的比例达到37%、41%、46%、50%、55%和60%（范围为每千克日粮含4.40至7.15克SID异亮氨酸）。基础日粮主要由玉米、小麦、大麦、马铃薯蛋白、血红蛋白粉和豆粕组成（粗蛋白：150克/千克；净能：10.46兆焦/千克；SID赖氨酸：12.0克/千克），且被认为异亮氨酸含量不足（每千克日粮含4.40克SID异亮氨酸）。从断奶后6天开始，在4周的时间内测量日采食量（dFI）、体重增加（BWG）和饲料转化率（FCR）。应用折线模型和二次模型进行回归分析，以得出断奶后仔猪低蛋白日粮中SID异亮氨酸相对于SID赖氨酸的最佳比例。饲喂基础日粮的仔猪的BWG、dFI显著低于饲喂添加异亮氨酸日粮的动物，且FCR更高（P < 0.05）。dFI和BWG均对日粮中异亮氨酸水平的增加呈现剂量依赖性反应。基于二次模型的回归分析，dFI和BWG的SID异亮氨酸与赖氨酸的最佳比例分别估计为52.6%和52.5%。得出的结论是，在断奶后给仔猪饲喂低蛋白日粮时，优化dFI和BWG的SID异亮氨酸相对于赖氨酸的最佳比例为52%。
