Effects of adding yeast on blood biochemistry, immunity and production performance of dairy cows
Probiotics have received extensive attention as a new type of safe, efficient and non-polluting feed additive. Probiotics mainly include yeast preparations, lactic acid bacteria preparations, Bacillus preparations and mixed bacteria preparations. Saccharomyces cerevisiae (Saccha romyces cerevisiae) is the most widely used yeast, which is mainly divided into two types: active yeast preparations and yeast culture preparations. Saccharomyces cerevisiae is widely used in the production of dairy cows, and there are many studies on the health status and milk production performance of dairy cows. Yeast-fermented feed can improve the rumen fermentation function and improve feed utilization (Ouellet, 2016), and at the same time, it can protect the body’s health, reduce the occurrence of diseases, and increase economic benefits (Wu Xiaoyan, 2014). The effect of active yeast and its fermented feed on rumen fermentation parameters was evaluated in vitro, and it was found that active yeast significantly increased the content of bacterial protein in the in vitro fermentation broth, and the effect was better than that of fermented feed (Zhang Zheng, 2017). Yeast culture is also widely used in dairy cow production. It can be added to dairy cow feed as an additive to improve the negative energy balance of dairy cows during the perinatal period (YE Gengping, 2014). The research on the effect of adding active yeast or yeast culture alone on milk production and performance of dairy cows is common, but adding active yeast and its culture on milk production performance, feed intake, blood biochemical indicators and immune Few studies have been reported on the impact of force. The experiment was conducted by adding a certain dose of active yeast and yeast culture to the dairy cow's diet to explore its effects on milk production performance, feed intake, blood biochemical indexes and immunity of dairy cows in different lactation periods.
According to a two-factor completely randomized block design, 48 lactating Holstein dairy cows with the same parity and similar body weight [(534±20) kg] were selected. 24 animals were selected in each period and randomly divided into 4 groups with 6 animals in each group. The experimental treatments of each group were as follows: the control group (CG group) was fed the basal diet; the other three experimental groups were supplemented with 0.075% yeast (LY group) and 0.100% selenium-enriched yeast (SY group) on the basis of the control group. And 0.075% yeast and 0.100% selenium-enriched yeast mixture (LY+SY group). The total period of the experiment was 45d, including 10d pre-feeding period and 35d formal period.
Yeast and selenium-enriched yeast products are purchased from the market. The viable count of yeast is 1.5×10 10 cfu/g; the content of selenium in yeast is 0.200%, and the moisture content is less than 6%.
1 Dry matter intake and lactation efficiency of dairy cows
It can be seen from Table 1 that different treatments had no significant effect on the dry matter intake of dairy cows (P>0.05), but in the middle lactation period, the dry matter intake of dairy cows in the SY group was higher than that in the CG, LY, and LY+SY groups, respectively. At the early stage of lactation, the feed utilization rate of the SY group was significantly lower than that of the LY and LY+SY groups (P<0.05). No significant effect (P>0.05).
Table 1 TMR feed intake and lactation efficiency of dairy cows
2 Milk production and milk quality of dairy cows
It can be seen from Table 2: in the early stage of lactation, the milk production of different treatment groups was significantly different, and the milk production of the CG and SY groups was significantly higher than that of the LY group (P<0.05); in the middle lactation, the milk production of the SY group was the highest. , which were 17.79%, 20.04% and 20.82% higher than those in the CG, LY and LY+SY groups, respectively (P<0.05). For milk protein content, in the early lactation, the milk protein content of different treatment groups was the lowest in the SY group (P<0.05), while there was no significant difference between the three groups of CG, LY and LY+SY (P>0.05); There was no significant difference in milk protein content between different treatment groups (P>0.05). There were no significant differences in the contents of milk fat, lactose, total solids and non-fat solids in milk of different treatment groups (P>0.05).
Table 2 Milk production and milk quality of dairy cows
3 Dairy cow blood biochemical indicators
It can be seen from Table 3 that in the early stage of lactation, the content of AMY in the blood of dairy cows was the highest in the CG group, which was not significantly different from the other three treatment groups. In mid-lactation, the AMY content in the blood of cows in the LY+SY group was significantly higher than that in the other three treatment groups (P<0.05), which were 15.67%, 18.43% and 19.81% higher than those in the CG, LY and SY groups, respectively. At the same time, the LDH content in the blood of dairy cows in the mid-lactation was also the highest in the LY+SY group, which was significantly higher than the other three groups (P<0.05), 9.05% and 12.94% higher than the CG group, the LY group and the SY group, respectively. and 10.18%. For the BUN content in blood, there were differences in different lactation stages of different treatment groups. In the early lactation period, the BUN content in the blood of cows in the four treatment groups was the lowest in the SY group, and was significantly lower than that in the LY group (P<0.05), among the other three treatment groups and between the SY and CG and SY+LY treatment groups The differences were not significant (P>0.05). In mid-lactation, the BUN content in the blood of dairy cows was the lowest in the LY group (P<0.05). Among the indicators measured in this experiment, except for the above-mentioned indicators, there were significant differences, and other indicators were not significantly different.
Table 3 Cows blood biochemical indexes
4 Immune globulin content of cows
It can be seen from Table 4: in the early stage of lactation, the content of IgA and IgM in the blood of dairy cows was the highest in the LY+SY group, but there was no significant difference between the groups (P>0.05), and the IgG content in the LY+SY group was the lowest, significantly lower than that in LY and SY groups (P<0.05); while in mid-lactation, the content of IgA in plasma was the highest in the CG group (P>0.05), the content of IgM in the SY group was the highest (P>0.05), and the content of IgG in the LY+SY group was the highest (P>0.05). The content of the group was the highest, which was significantly higher than that of the CG and SY groups (P<0.05), which were 45.56% and 46.59% higher, respectively.
Table 4 Immune globulin content in cow plasma (mg/mL)
Based on the above data, it is shown that adding a certain amount of yeast culture to the dairy cow's diet has a certain positive significance for improving the immunity of the animal body, improving the health status of the body, and promoting the healthy and sustainable development of the dairy cattle breeding industry.