Kellner T A, Gourley G G, Wisdom S, Patience J F
J Anim Sci. 2016 Dec;94(12):5248-5261. doi: 10.2527/jas.2016-0643.
The pig industry uses a variety of fat sources (FS) and fat levels (FL) in diets to increase energy content. The objective was to investigate the impact of FS and FL on rate and efficiency of gain, apparent total tract digestibility of dietary fat, and pork fat composition and test dietary predictors of carcass iodine value (IV). A total of 1,213 pigs (PIC 280 × PIC Camborough 42; PIC, Inc., Hendersonville, TN) with an initial BW of 32.0 ± 0.4 kg were randomly allotted to 1 of 6 dietary treatments on d 0. Treatments were arranged as a 2 × 3 factorial, with 2 FS, choice white grease (CWG; IV = 66.8) and corn oil (COIL; IV = 123.2), and 3 FL, 2, 4, or 6%. Ten pens of approximately 20 pigs each (0.70 m/pig) were randomly assigned to each of the 6 treatments. All pigs were on trial for 105 d. Pigs were harvested in 1 of 3 marketing pulls, to achieve an ideal market BW across differing rates of gain, at which time belly fat samples were collected (d 105 [457 pigs], 117 [309 pigs], or 134 [432 pigs]). Diet and belly fat samples were analyzed for fatty acid profile. Daily rate of gain was not impacted by FS or FL ( ≤ 0.325). Increasing FL and dietary energy concentration increased G:F ( < 0.001). No difference was evident for G:F between FS ( = 0.107). Increasing FL of CWG resulted in greater daily intake of SFA and MUFA than increasing FL of COIL ( < 0.001). Increasing levels of COIL resulted in greater daily intake of PUFA than increasing levels of CWG ( ≤ 0.012). Feeding CWG tended to result in great caloric efficiency adjusted for carcass yield than feeding COIL ( = 0.074). The inclusion of COIL instead of CWG tended to increase true total tract digestion of acid hydrolyzed ether extract on d 39 ( = 0.066) but not on d 104 ( = 0.402). Increasing COIL increased carcass IV at a greater magnitude than increasing CWG, resulting in a FS × FL interaction on d 105, 117, and 134 ( < 0.001). Dietary linoleic acid concentration and daily intake had a stronger linear relationship than IV product (IVP; = 0.95 vs. = 0.94 vs. = 0.85, respectively). In conclusion, limiting linoleic acid dietary concentration and intake is key to lowering carcass IV. To meet a carcass IV standard of 74 g/100 g, linoleic acid concentration had to be <3.4% and intake had to be <88 g/d. Dietary linoleic acid is a superior predictor of carcass IV compared with IVP, especially when high-fat diets are used.
养猪业在日粮中使用多种脂肪来源（FS）和脂肪水平（FL）来提高能量含量。目的是研究FS和FL对生长速度和效率、日粮脂肪的表观全肠道消化率、猪肉脂肪组成的影响，并测试胴体碘值（IV）的日粮预测指标。总共1213头猪（PIC 280×PIC坎布罗42；PIC公司，田纳西州亨德森维尔），初始体重为32.0±0.4千克，于第0天随机分配到6种日粮处理中的1种。处理按2×3析因设计，有2种FS，即精选白油脂（CWG；IV = 66.8）和玉米油（COIL；IV = 123.2），以及3种FL，分别为2%、4%或6%。每种6种处理各随机分配10个栏，每个栏约20头猪（每头猪0.70平方米）。所有猪试验105天。猪分3批出栏，以在不同生长速度下达到理想的上市体重，此时采集腹部脂肪样本（第105天[457头猪]、117天[309头猪]或134天[432头猪]）。分析日粮和腹部脂肪样本的脂肪酸谱。日增重不受FS或FL的影响（P≤0.325）。增加FL和日粮能量浓度可提高料重比（P<0.001）。FS之间的料重比无明显差异（P = 0.107）。与增加COIL的FL相比，增加CWG的FL导致饱和脂肪酸（SFA）和单不饱和脂肪酸（MUFA）的日摄入量更高（P<0.001）。与增加CWG的水平相比，增加COIL的水平导致多不饱和脂肪酸（PUFA）的日摄入量更高（P≤0.012）。饲喂CWG相比于饲喂COIL，经胴体产量调整后的热量效率往往更高（P = 0.074）。用COIL替代CWG在第39天倾向于提高酸水解乙醚提取物的真全肠道消化率（P = 0.066），但在第104天无此差异（P = 0.402）。增加COIL比增加CWG更能提高胴体IV，在第105天、117天和134天导致FS×FL交互作用（P<0.001）。日粮亚油酸浓度和日摄入量的线性关系比碘值乘积（IVP）更强（分别为P = 0.95、P = 0.94、P = 0.85）。总之，限制日粮中亚油酸的浓度和摄入量是降低胴体IV的关键。要达到74克/100克的胴体IV标准，亚油酸浓度必须<3.4%，摄入量必须<88克/天。与IVP相比，日粮亚油酸是胴体IV的更好预测指标，尤其是在使用高脂肪日粮时。
