Rocha Gabriel Cipriano, Duarte Marcos Elias, Kim Sung Woo
Department of Animal Science, Universidade Federal de Viçosa, Viçosa 36570-900, MG, Brazil.
Department of Animal Science, North Carolina State University, Raleigh, NC 27695, USA.
Animals (Basel). 2022 Dec 9;12(24):3478. doi: 10.3390/ani12243478.
Currently, five crystalline essential amino acids (Lys, Met, Thr, Trp, and Val) are generally used, allowing formulation of low-crude-protein (CP) diets. Moreover, Ile may also be used depending on its economic value and the specific feeding program. Experimentally, it has been shown that further reduced CP levels can be achieved by supplemental His, Leu, and Phe to the diets. However, decreasing the dietary CP level while maintaining optimal ratios of amino acids has shown contradictory effects on pigs' growth performance. Due to the divergence in the literature and the importance for practical formulation strategies in the swine industry, a literature review and a meta-analysis were performed to estimate the minimum CP level that would not compromise pig performance. Based on the present review, there is a minimum CP level after which the growth performance of pigs can be compromised, even though diets are balanced for essential amino acids. Considering average daily gain and gain to feed, respectively, these levels were estimated to be 18.4% CP (95% confidence interval [CI]: 16.3 to 18.4) and 18.3% CP (95% CI: 17.4 to 19.2) for nursery, 16.1% CP (95% CI: 16.0 to 16.2) and 16.3% CP (95% CI: 14.5 to 18.0) for growing, and 11.6% CP (95% CI: 10.8 to 12.3) and 11.4% CP (95% CI: 10.3 to 12.5) for finishing pigs.
目前，通常使用五种结晶必需氨基酸（赖氨酸、蛋氨酸、苏氨酸、色氨酸和缬氨酸），从而可以配制低粗蛋白（CP）日粮。此外，异亮氨酸也可根据其经济价值和具体饲养方案使用。实验表明，通过在日粮中添加组氨酸、亮氨酸和苯丙氨酸，可以进一步降低CP水平。然而，在保持氨基酸最佳比例的同时降低日粮CP水平，对猪的生长性能显示出矛盾的影响。由于文献存在分歧以及其对养猪业实际配方策略的重要性，因此进行了文献综述和荟萃分析，以估计不会影响猪性能的最低CP水平。根据目前的综述，存在一个最低CP水平，超过这个水平，即使日粮中必需氨基酸平衡，猪的生长性能也可能受到影响。分别考虑平均日增重和料重比，保育猪的这些水平估计为18.4%CP（95%置信区间[CI]：16.3至18.4）和18.3%CP（95%CI：17.4至19.2），生长猪为16.1%CP（95%CI：16.0至16.2）和16.3%CP（95%CI：14.5至18.0），育肥猪为11.6%CP（95%CI：10.8至12.3）和11.4%CP（95%CI：10.3至12.5）。
