Objectives were to determine the effects of reducing dietary nutrient density after the second dose of GnRF immunization (Improvest; Zoetis Inc.) on growth performance and carcass characteristics. Pigs (n = 1,008) were fed in five diet phases during the 102-d grow-finish period. Diets were formulated to meet 100% of recommended SID Lys to net energy established by PIC (2021) for physically castrated (PC) barrows/non-immunized gilts (regular diet), while diets for GnRF-immunized pigs were formulated with 120% SID lysine than PC barrows/ non-immunized gilts (nutrient-dense diet). During diet phase-4 (2 d after the second GnRF analogue dose), SID lysine and vitamins/trace minerals for the nutrient-dense diet were either maintained at 100% or reduced to 95% or 90%. During diet phase-5 (18 d after second GnRF analogue dose), SID lysine and vitamins/trace minerals nutrient-dense diet were either maintained at 100% or reduced to 90% or 80%. The study consisted of six pen replications (21 pigs/pen) of the following eight treatments: CON-NEG: traditional mixed-sex pigs (PC barrows and non-immunized gilts) that received the regular diet; CON-POS: traditional mixed-sex pigs that received the nutrient-dense diet; I-MALE-100: immunized males (I-MALES) that received the nutrient-dense diet with 100% density; I-MALE-95/90: I-MALES that received the nutrient-dense diet with 95% density during diet phase-4 and 90% density during diet phase-5; I-MALE-90/80 I-MALES that received the nutrient-dense diet with 90% density during diet phase-4 and 80% density during diet phase-5; I-FEM-100: immunized females (I-FEM) that received the nutrient-dense diet with 100% density; I-FEM-95/90: I-FEM that received the nutrient-dense diet with 95% density during diet phase-4 and 90% density during diet phase-5; I-FEM-90/80: I-FEM that received the nutrient-dense diet with 90% density during diet phase-4 and 80% density during diet phase-5. Data were analyzed with PROC MIXED of SAS, with pen serving as the experimental unit. In addition, linear effects of diet dilution for I-MALE and I-FEM pigs were tested using contrast statements. There were not significant linear effects of diet dilution for gain:feed or hot carcass weight in either the I-MALE (P > 0.28) or I-FEM (P > 0.78) pigs. For the overall period, gain:feed was improved by 7.4% for I-MALE pigs compared with the CON-NEG pigs and was improved by 1.6% for the I-FEM pigs compared with the CON-NEG pigs. Hot carcass weight was 3.6 kg greater for the I-MALE pigs compared with the CON-NEG pigs and 1.6 kg greater for the I-FEM pigs compared with the CON-NEG pigs. The results would suggest that removing nutrients during the post-second dose period of GnRF immunization does not negatively affect growth performance or carcass characteristics, while both I-MALE and I-FEM pigs are more efficient and heavier when compared with traditional mixed sex pigs.

中文翻译：

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440 第二剂 GnRF 免疫后降低日粮营养密度 （Improvest） 对后备母猪和完整雄猪生长性能和胴体特性的影响


目的是确定在第二剂 GnRF 免疫后降低膳食营养密度的效果（改善最;硕腾公司）关于生长性能和胴体特征。猪 （n = 1,008） 在 102 天生长-完成期间分 5 个饮食阶段饲喂。日粮的配方满足 PIC （2021） 为身体去势 （PC） 的母猪/未免疫的后备母猪（常规日粮）确定的 100% 推荐 SID 赖氨酸，而 GnRF 免疫猪的日粮配方中含有 120% 的 SID 赖氨酸，比 PC 牛/未免疫的后备母猪（营养密集日粮）。在饮食阶段 4 （第二次 GnRF 类似物剂量后 2 天），营养密集型饮食的 SID 赖氨酸和维生素/微量矿物质维持在 100% 或降低至 95% 或 90%。在饮食阶段 5 （第二次 GnRF 类似物剂量后 18 天），SID 赖氨酸和维生素/微量矿物质营养密集型饮食维持在 100% 或降低至 90% 或 80%。 该研究包括以下 8 个处理的 6 个猪栏重复（21 头猪/栏）：CON-NEG：接受常规饮食的传统混性猪（PC 屁股和未免疫的后备母猪）;CON-POS：接受营养丰富的饮食的传统混种猪;I-MALE-100：接受 100% 密度营养密集饮食的免疫男性 （I-MALES）;I-MALE-95/90：接受营养密集饮食的 I-MALES，饮食阶段 4 期间密度为 95%，饮食阶段 5 期间密度为 90%;I-MALE-90/80 I-MALES 接受营养密集型饮食，饮食阶段 4 密度为 90%，饮食阶段 5 密度为 80%;I-FEM-100：接受 100% 密度营养密集饮食的免疫女性 （I-FEM）;I-FEM-95/90：I-FEM 接受营养密集的饮食，在饮食阶段 4 中密度为 95%，在饮食阶段 5 中接受密度为 90%的饮食;I-FEM-90/80：I-FEM 接受营养密集的饮食，在饮食阶段 4 中密度为 90%，在饮食阶段 5 中接受密度为 80%。使用 SAS 的 PROC MIXED 分析数据，笔作为实验单位。此外，使用对比声明测试了 I-MALE 和 I-FEM 猪日粮稀释的线性效应。日粮稀释对 I-雄性 （P > 0.28） 或 I-FEM （P > 0.78） 猪的增重：饲料或热胴体重量没有显著的线性影响。在整个期间，I-MALE 猪的增重：饲料比 CON-NEG 猪提高了 7.4%，I-FEM 猪的增重：饲料比 CON-NEG 猪提高了 1.6%。与 CON-NEG 猪相比，I-MALE 猪的热胴体重量增加了 3.6 kg，与 CON-NEG 猪相比，I-FEM 猪的热胴体重量增加了 1.6 kg。 结果表明，在 GnRF 免疫的第二剂量后阶段去除营养物质不会对生长性能或胴体特性产生负面影响，而与传统的混血猪相比，I-MALE 和 I-FEM 猪都更高效、更重。