Résumé
The aim of this study was to evaluate the effects of compound probiotics on milk performance,blood biochemical indexes,rumen fermentation parameters and nutrient digestibility of Holstein dairy cows in middle-and-later lactation.Forty-eight dairy cows with similar milk yield,days in milk and age were randomly divided into 4 groups treated with four different levels of compound probiotics as follows:the control group (0 g/d),group 1 (10 g/d),group 2 (20 g/d) and group 3 (30 g/d).The adaptation period was 7 days,and the total experimental period was 60 days.Results showed that:compared with the control group,supplementation of compound probiotics could improve milk yield and significantly increase the concentration of milk protein,lactose and total solids (P＜0.05);there was no significant effect on blood biochemical indexes (P＞ 0.05);compound probiotics could significantly increase the content of ammonia and microbial protein content (MCP) in the rumen (P＜ 0.05);the apparent nutrient digestibility of crude protein and crude fat of group 2 was significantly higher than other groups (P＜0.05);compared with the control group,the economic benefits of group 1,2,3 increased 2.28,4.80 and 4.09 yuan/d,respectively.In summary,dietary supplementation with 20 g/d of compound probiotics was the most effective method for milk performance,rumen fermentation parameters,nutrients apparent digestibility and economic benefit of Holstein dairy cows.
Résumé
Objective: To investigate the effect of four kinds of inactivation methods on the activity of soybean agglutinin (SBA). Methods: Dry-heat, humid-heat, acid-alkali and metal ion were employed to evaluate their effects on the activity of SBA, which were quantified by hemagglutination. Results: Dry-heat below 120℃ did not obviously decrease the activity of SBA, while humid-heat (95℃ for 30 min,100℃ for 20 min or 105℃ for 10 min) completely inactivated the SBA. The activity of SBA significantly decreased when soybean protein was extracted under pH 1.0-4.5 or pH 9-13. Quadrivalent and trivalent metal ions markedly inhibited the activity of SBA. Conclusion: SBA can be inactivated effectively by humid-heat, acid-alkali or metal ion. Further study is needed to clarify whether there are synergistic effects between these treatments.