免疫应激对仔猪生产性能和蛋白质需求规律的影响

【作者】 吕继蓉；

【导师】 陈代文； 张克英；

【作者基本信息】 四川农业大学 ， 动物营养学， 2002， 硕士

【摘要】 本试验采用2×3因子设计，探索免疫应激对仔猪生产性能、蛋白质利用和需求规律的影响。仔猪免疫状况设高应激状态和低应激状态(高应激组通过注射血清型为O55：B5的丘Coli.脂多糖诱导产生；低应激组注射生理盐水)二种水平，日粮蛋白水平设17％、20％和23％三种水平。选用28日龄断奶的长荣(长白×荣 二元杂交仔猪36头，预饲一周后随机分成6个处理，每个处理6个重复，每个重复1头猪。高应激组在试验的第1、3、5和7天注射脂多糖，剂量为200ug／kg体重，低应激组按体重注射相应体积的无菌生理盐水。试验全期共21天，在试验的3-21天进行氮平衡试验，测定仔猪对蛋白质的利用率，同时考查仔猪的生产性能；通过测定血清免疫球蛋白水平和T淋巴细胞转化率来反映仔猪免疫状况。 结果表明：(1)多次注射LPS激活了仔猪免疫系统，表现在显著提高试验第3天T淋巴细胞转化率(P＜0.01)，而在试验的后期(第14天)，注射LPS对T淋巴细胞转化率影响不显著；从各阶段来看，注射LPS未显著影响仔猪血清抗体水平(P＞0.05)。(2)免疫应激明显降低仔猪的生产性能。表现在试验的1-6天，高应激组的ADG、ADFI和G/F分别比低应激组低45％、25％和23％；免疫应激对1-9天仔猪生产性能的影响与试验1-6天相似，但影响程度小于1-6天。在试验的后期(14-21天)仔猪生产性能在两组间差异不显著(P＞0.05)。(3)饲粮蛋白质水平影响应激仔猪的生产性能。在试验的1-6天，17％蛋白水平组有较高的ADFI、ADG和G/F，其中G/F显著高于20％、23％蛋白水平组(P＜0.05)；在试验的14-21天，则是应激仔猪在23％蛋白水平组中有较高的G/F、ADG。(4)免疫应激降低了试验3-9天仔猪对蛋白质的消化率、吸收率和日沉积蛋白量，影响了仔猪蛋白质代谢，表现在应激使仔猪对饲粮蛋白的消化率、生物学价值、日沉积蛋白量分别降低3％、3％、15％，尿氮排出率提高43.8％；在试验的14-21天，应激仍然影响了仔猪对饲粮蛋白的利用率，但程度小于试验的第3-9天。(5)蛋白水平除了对应激仔猪3-9天日蛋白质沉积无影响外(P＞0.05)，极显著影响了其余各阶段应激仔猪的日沉积蛋白量(P＜0.01)。 通过本试验的研究发现，免疫应激降低了仔猪对饲粮蛋白质的利用率和仔猪的生产性能；在免疫应激期及应激后的恢复期，仔猪对蛋白水平的需求不同：在应激期，仔猪对蛋白水平的需要降低，在恢复期，仔猪对蛋白水平的需要升高；就本试验所设蛋白水平来看，10-20kg仔猪在免疫应激期对饲粮蛋白质的需要量为17％，应激结束后的恢复期为23％；而低应激仔猪在相应时期的蛋白质需要量均为20％。更多还原

【Abstract】 A 2x3 factorial nitrogen balance trial was conducted to explore the influence of immune stress and dietary crude protein(CP) on growth performance and protein utilization and requirement of young pigs. Immune system of pigs was activated in stress groups by intramuscular injection of Escherichia coli lipoploysaccaride(LPS, serotype O55:B5) . Pigs in non-stress groups were not challenged by LPS. Dietary protein levels were designed as 17%, 20%, and 23% . A total of 36 crossbred (Landracex Rongchang) pigs weaned at 28 days were randomly allotted to 6 treatments with 6 replicate each. The trial was conducted for 21 days. On d 1, d 3, d 5 and d 7 of the experiment, piglets in stress groups were challenged with LPS at a dose of 200ug/kg bogy weight. Pigs in non-stress groups were injected with 0.9% sterile saline. Feed consumption and bodyweight of pigs were recorded during the trial. CP digestibility, biological value and body protein retention were determined by nitrogen balance from d 3 to 21 d .Lymphocyte blastogenesis and serum immunoglobulins were measured to monitor piglets’immune status.The results showed: 1) Repeated injections of LPS increased significantly lymphocyte blastogenesis ratio on d 3 (PO.01), but lymphocyte blastogenesis ratio on d 14 was not significantly different among treatments, indicating immune system was activated by LPS injection. The level of serum immunoglobulins was not different between stress- and non-stress groups at each stage (P>0.05). 2) Immune challenge reduced growth performance of piglets. Average daily gain(ADG), average feed daily intake (ADFI) and feed efficiency (G/F) in stress groups were 43% ,25%, and 23% lower respectively than those in non-stress groups during d 1 to d 6 and ADG was 28% lower during d 1 to d 9. Growth performance during d 14 to d 21 was not affected by stress treatment (P>0.05). 3) Piglets consuming 17%CP diet had higher ADG and G/F than pigs fed 20% or 23%CP diet when piglets were challenged with LPS during d 1 to d 6. During d 14 to d 21, piglets fed 23%CP in stress group had the highest G/F ratio and ADG than pigs fed 17% or 20% CP diet. The results showed that piglets needed lower dietary crude protein(CP) during stress and higher CP after immune stress for their compensatory growth.. 4) LPS administration reduced the utilization efficiency of crude protein (P>0.05) and the effect was greater during d 3 to d 9 than that during d 14 to d 21. During d 3 to d 9, protein digestibility, biological value, protein retention were lower 3%,3%,15% respectively in stress groups compared with non-stress groups . Urinary nitrogen excretion in the stress groups increased by 43.8% compared to non-stress control during d 3 to d 6. 5) Dietary CP levels affected significantly protein retention in stress groups at each stage (P<0.00) with exception to the stage of d 3 to d 9.in conclusion, immune stress influences dietary protein utilization and pig performance. Dietary protein requirement during and after stress is inconsistent to that of healthy piglets. In this study, piglets need 17% CP during immune stress and 23%CP during the compensatory growth after stress, while healthy piglets need 20% CP during the same period.更多还原