Department of Animal Science, Iowa State University, Ames, IA.
J Anim Sci. 2019 Jul 30;97(8):3451-3459. doi: 10.1093/jas/skz194.
Phytase is added to swine diets to improve the utilization of phytate-bound P in swine diets. This provides financial and environmental benefits to the pig industry. However, it is unclear if phytase works equally well in all dietary circumstances. The objective of this experiment was to determine if insoluble fiber affects the efficacy of the phytase enzyme in nursery pigs when fed diets limiting in P content. A total of 480 pigs (initial BW 5.48 ± 0.14 kg) were blocked by BW and randomly assigned (10 pigs per pen) to treatment within the block. A common nutrient-adequate diet was fed from days -14 to -5, and two basal P deficient diets (either a corn-soy diet containing 0.16% standardized total tract digestible [STTD] P [low insoluble fiber [LF]], or a corn-soybean meal plus 20% corn bran containing 0.14% STTD P [high insoluble fiber [HF]]) were fed from days -5 to 0 to acclimate pigs to a P deficient diet. From days 0 to 21, pigs received eight dietary treatments (six pens per treatment: n = 6). Experimental diets consisted of LF supplemented with one of four levels of added phytase (0, 109, 218, and 327 phytase units [FTU]/kg; Quantum Blue 5 G, AB Vista, Wiltshire, United Kingdom) expected to provide 0.16, 0.21, 0.26, and 0.31% STTD P, respectively, or HF supplemented with one of the same four levels of added phytase expected to provide 0.14, 0.19, 0.24, and 0.29% STTD P. Titanium dioxide was added to the diet at 0.4% as an indigestible marker. On day 21, one pig representing the average BW for each pen was euthanized, and fibulae were collected and analyzed for bone ash. Fecal samples were collected from each pen on days 19-20. Data were analyzed using PROC MIXED of SAS. There were no interactions between insoluble fiber and phytase for any of the variables evaluated. For days 0-21, adding phytase increased ADG (P < 0.001) with the response being linear (P < 0.001), whereas insoluble fiber decreased ADG (P = 0.033). There were no effects of phytase or insoluble fiber on ADFI (P = 0.381 and P = 0.632, respectively). Phytase improved G:F ratio (P < 0.001) with the response being linear (P < 0.001). Insoluble fiber tended to decrease G:F ratio (P = 0.097). Phytase increased bone ash (P = 0.005) with the response being linear (P = 0.001), but there was no effect of insoluble fiber (P = 0.949). Phytase did not affect the apparent total tract digestibility of DM, NDF, or ADF (P > 0.050), whereas insoluble fiber decreased the ATTD of DM (P < 0.001), NDF (P < 0.001), and ADF (P < 0.001). In conclusion, the addition of insoluble fiber did not affect the ability of phytase to improve growth performance and bone mineralization in nursery pigs fed a P deficient diet.
植酸酶被添加到猪饲料中，以提高猪饲料中植酸结合磷的利用率。这为养猪业带来了经济和环境效益。然而，目前尚不清楚植酸酶在所有饲养情况下是否同样有效。本试验的目的是确定在饲粮磷含量有限的情况下，不溶性纤维是否会影响仔猪饲粮中植酸酶的功效。将 480 头猪（初始体重 5.48±0.14kg）按体重分为若干个区组，并在区组内随机分配（每个区组 10 头猪）至处理组。从第-14 天到第-5 天，所有猪饲喂基础饲粮，该基础饲粮养分充足；从第-5 天到第 0 天，两种基础磷缺乏饲粮（一种是含有 0.16%标准总可消化磷[STTD]的玉米-豆粕饲粮，低不溶性纤维[LF]；另一种是含有 0.14%STTD 的玉米-豆粕和 20%玉米糠饲粮，高不溶性纤维[HF]）用于适应磷缺乏的饲粮。从第 0 天到第 21 天，猪接受 8 种饲粮处理（每种饲粮处理 6 个重复：n=6）。试验饲粮由 LF 组成，添加 4 个水平的植酸酶（0、109、218 和 327 植酸酶单位[FTU]/kg；AB Vista 公司的 Quantum Blue 5G），分别预期提供 0.16%、0.21%、0.26%和 0.31%STTD P，或 HF 添加相同的 4 个水平的植酸酶，预期提供 0.14%、0.19%、0.24%和 0.29%STTD P。饲粮中添加 0.4%的二氧化钛作为不消化的标记物。在第 21 天，每个重复随机选取 1 头体重接近平均体重的猪进行安乐死，收集腓骨并分析骨灰分。在第 19-20 天收集每个重复的粪便样本。试验数据采用 SAS 的 PROC MIXED 程序进行分析。在所有评估的变量中，不溶性纤维和植酸酶之间没有互作。在 0-21 天，添加植酸酶提高了 ADG（P<0.001），且呈线性关系（P<0.001），而不溶性纤维降低了 ADG（P=0.033）。植酸酶和不溶性纤维对 ADFI 没有影响（P=0.381 和 P=0.632）。植酸酶提高了 G:F 比（P<0.001），且呈线性关系（P<0.001），而不溶性纤维降低了 G:F 比（P=0.097）。植酸酶提高了骨灰分（P=0.005），且呈线性关系（P=0.001），而不溶性纤维降低了 DM、NDF 和 ADF 的表观全肠道消化率（P>0.050）。综上所述，在饲粮磷含量有限的情况下，添加不溶性纤维不影响植酸酶提高仔猪生长性能和骨矿化的能力。
