Effects Of Three Seaweed Feeds On Performance, Rumen Environment And Health Status Of Dairy Cows

Seaweed is a general term for algae in the ocean.It is distributed in the shallow sea area below the low tide line and is a hidden flower plant in the plant kingdom.There are more than 30,000 kinds of algae known in the world.The algae that has been developed and utilized by humans is mainly divided into four major categories:red algae,brown algae,green algae and cyanobacteria.With the tight supply of conventional feed ingredients and rising prices,the development of unconventional integrated functional feeds has become a long-term task to address the effective supply of animal feed resources.As a high-quality unconventional seaweed feed resource,kelp has the characteristics of wide distribution,large yield,good adaptability,and contains a large number of bioactive substances and nutrients lacked by terrestrial plants.These characteristics determine its huge feed economic development value.However,there are few researches on the application of seaweed in China to ruminants.Therefore,this study selected three typical seaweed species in China to explore their effects on dairy performance,rumen fermentation and health status.The research results are as follows:Experiment 1 was conducted to compare the effects of kelp,laver and wakame on the rumen in vitro fermentation of dairy cows.Ten healthy,similar,three-child Holstein cows were used for oral collection of rumen fluid.Each seaweed test group was designed to add 0,2%,4%,6%,8%,and 10%,and each group was set to 6 replicates.A total of 3 batches were tested.After 48 hours of in vitro fermentation,the pH value and rumen fermentation parameters of the sample fermentation broth were tested.The results showed that:1.4-10%feed ratio of kelp powder can significantly reduce the total gas production of fermentation broth,2%and 4%kelp powder ratio significantly reduced the NH₃-N concentration,significantly increased the MCP concentration?P<0.05?,when the feed ratio is 6-10%,the indicators change in the opposite direction;2.Adding 0-8%seaweed powder can significantly increase the total gas production and MCP production?P<0.05?;3.Adding 0-4%of wakame can significantly increase total gas production and MCP yield?P<0.05?.Therefore,under the conditions of in vitro culture,the addition of three seaweed powders can effectively regulate the rumen fermentation environment,and promote or inhibit the production of rumen fermentation products and change the gas production according to the amount of addition.Experiment 2 aims to investigate the effects of kelp powder as a feed ingredient on dairy cow performance,rumen fermentation parameters and blood biochemical immune indicators.Twenty fetal Holstein cows with a healthy weight of 605±36.1 kg were randomly divided into 4 groups,5 in each group,and two-factor random trial design?fine material level 45%,55%?.×?kelp level 0%,5%?.In a35-day single-cycle study,cows were provided with an equal energy fully mixed diet based on corn silage.Measurement of lactation performance,rumen fermentation and serum biochemical immune parameters.The results showed that:1.Compared with the control group,the iodine content in the 5%kelp powder group increased significantly;the addition of kelp powder and the reduction of the concentration level could increase the milk fat concentration?P<0.01?;2.The kelp powder significantly reduced the ammonia nitrogen.And microbial protein concentration,but increased the concentration of acetic acid and total volatile fatty acids in the rumen?P<0.05?;3,kelp powder significantly increased serum total protein concentration,serum concentration of AST was significantly reduced?P<0.05?.Therefore,kelp powder can improve the lactation performance of cows at two dietary levels,regulate rumen fermentation mode and blood metabolites,and has potential for feed application.Experiment 3 aims to further investigate the effects of kelp powder on the rumen bacterial flora of dairy cows at high concentrate levels.The microbial phylogenetic analysis was performed based on the rumen fluid sampled in Test 2.The results showed that:55%concentration diet supplemented with 5%kelp powder reduced the unique OTU number of the sample,but had no significant effect on bacterial?diversity?P>0.05?.At the level of the door,the abundance of Bacteroidetes was significantly decreased after supplementing 5%kelp powder in high-precision diet?P<0.05?,and the abundance of thick-walled bacteria was significantly increased?P<0.05?.Concentrate diets further significantly increased the abundance of actinomycetes?P<0.05?.At the genus level,the addition of 5%kelp powder further significantly reduced Prevotella₁ levels and increased Ruminococcus-2 levels?P<0.05?compared with the 55%high concentrate group.Therefore,adding 5%of kelp powder to high-concentration diet of dairy cows can improve the rumen fermentation environment under high-concentration diet and adjust the level of rumen bacterial flora,which has little effect on rumen bacterial diversity.In summary,seaweed feed resources can effectively regulate the production performance,rumen fermentation status and oxidative stress of dairy cows,improve the rumen bacterial flora structure of high-precision dairy cows,improve the milk quality of dairy cows,and have certain production and application value.