β-胡萝卜素对奶牛泌乳高峰期产乳性能及血常规指标、血清生化和免疫指标的影响

Effects of Dietaryβ-carotene Supplementation on Lactation Performance,Blood Routine,Serum Biochemical and Immune Indexes of Dairy Cows during the Lactating Peak Period

【目的】研究饲粮中添加β-胡萝卜素对奶牛泌乳高峰期产奶性能、血常规指标、血清生化与免疫指标的影响。【方法】选用20头体况良好、平均体重为(550.00±32.71)kg、胎次为2~3胎的干奶期中国荷斯坦奶牛,随机分为4组,每组5头。对照组饲喂基础饲粮,试验组在基础饲粮中分别添加600、1200和1800 mg/dβ-胡萝卜素,试验从产犊前60 d至产犊后90 d,共150 d。试验期间测定奶牛产奶量、乳成分,试验结束时尾静脉采血,测定血常规,分离血清测定血清生化指标及免疫指标。【结果】与对照组相比,饲粮中添加β-胡萝卜素对奶牛泌乳高峰期产奶量、乳脂率、乳蛋白率和乳糖率影响不显著(P>0.05),添加600、1200 mg/dβ-胡萝卜素显著降低了牛乳中体细胞数(P<0.05);饲粮中添加β-胡萝卜素对奶牛血液白细胞计数(WBC)、红细胞计数(RBC)、血小板计数(PLT)、血红蛋白(HGB)和红细胞压积(HCT)均无显著影响(P>0.05);饲粮中添加1200、1800 mg/dβ-胡萝卜素显著提高了奶牛血清甘油三酯(TG)含量(P<0.05),添加600、1200 mg/dβ-胡萝卜素显著提高了血清高密度脂蛋白(HDL)含量(P<0.05);饲粮中添加600、1800 mg/dβ-胡萝卜素显著降低了奶牛血清CD4+含量(P<0.05),添加1200 mg/dβ-胡萝卜素显著降低了奶牛血清CD8+和肿瘤坏死因子-α(TNF-α)、白细胞介素-1β(IL-1β)、白细胞介素-2(IL-2)和γ-干扰素(IFN-γ)含量,并显著提高了血清CD4+/CD8+(P<0.05)。【结论】饲粮中添加适量β-胡萝卜素可以降低奶牛泌乳高峰期乳中体细胞数和血清炎性细胞因子含量,增强奶牛泌乳高峰期的细胞免疫功能。

【Objective】This experiment was conducted to study the effects of dietaryβ-carotene supplementation on lactation performance,blood routine indexes and serum biochemical and immune indexes of dairy cows during the lactating peak period.【Method】Twenty healthy Chinese Holstein dairy cows during the dry period with an average body weight of(550.00±32.71)kg and parities of 2-3 were randomly divided into 4 groups with 5 cows in each group.The cows in control group were fed a basal diet,the cows in experimental groups were fed the basal diet supplemented with 600,1200 and 1800 mg/dβ-carotene,respectively.The experiment lasted for 150 days from 60 days before calving to 90 days after calving.During the experiment,the milk yield and milk composition of dairy cows were measured.Blood was collected from the tail vein to determine the blood routine indexes,and isolated serum was used to determine the indexes of biochemistry and immune at the end of the experiment.【Result】Compared with the control group,dietaryβ-carotene supplementation had no significant effect on milk yield,milk fat rate,milk protein rate and lactose rate of dairy cows(P>0.05).600,1200 mg/dβ-carotene supplementation significantly reduced somatic cells number of dairy cows(P<0.05).Dietaryβ-carotene supplementation had no significant effect on blood white blood cell count(WBC),red blood cell count(RBC),platelet count(PLT),hemoglobin(HGB)and hematocrit(HCT)(P>0.05).1200 and 1800 mg/dβ-carotene supplementation significantly increased serum triglyceride(TG)content(P<0.05),600,1200 mg/dβ-carotene supplementation significantly increased serum high density lipoprotein(HDL)content(P<0.05).600 and 1800 mg/dβ-carotene supplementation significantly reduced the serum CD4+content of dairy cows(P<0.05),1200 mg/dβ-carotene supplementation significantly decreased the contents of serum CD8+,tumor necrosis factor-α(TNF-α),interleukin-1β(IL-1β),interleukin-2(IL-2)and interferon-γ(IFN-γ)contents,and significantly increased CD4+/CD8+ratio in serum of dairy cows(P<0.05).【Conclusion】In conclusion,appropriate ofβ-carotene in diet could reduce somatic cell count in milk and inflammatory cytokines,and enhance cellular immune function of dairy cows during the lactating peak period,and 1200 mg/d was the appropriate supplemental level.