Meta-analysis of the Effect of Adding DHA-rich Algae on the Production Performance of Lactating Dairy Cows
To investigate the effect of adding DHA-rich algae to the diet on the production performance of lactating cows,a meta-analysis was conducted on 15 literatures.The combined effect size was expressed as standard mean difference(SMD)and 95％confidence interval(95％CI).The heterogeneity among studies was tested by x2 test.Meta-regression analysis and subgroup analysis were used to explore the reasons for heterogeneity.The Egger's test was used to test publication bias.The results showed that the combined effect SMD value of dry matter intake was 0.11(95％CI:-0.01～0.22,P=0.07),and that of milk yield was 0.11(95％CI:-0.01～0.22,P=0.07).When the DHA addition dose was＜20g/d,the combined effect SMD value was-0.261(95％CI:-0.392～-0.130,P＜0.001);when the DHA addition dose was＞20g/d,it was-1.725(95％CI:-2.036～-1.414,P＜0.001),and the total effect value was-0.482(95％CI:-0.603～-0.361,P＜0.001).The combined effect values of milk protein rate and milk lactose rate were-0.295(95％CI:0.103～0.486,P=0.030)and 0.028(95％CI:-0.098～0.153,P=0.664),respectively.These results indicate that adding DHA-rich algae has no significant effect on feed intake and milk lactose rate,but has a trend of increasing milk yield.At the same time,adding DHA-rich algae can significantly reduce milk fat rate and milk protein rate,especially when the DHA addition dose is＞20g/d,the decrease in milk fat rate is more significant.
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