Effects Of Different Fat Source Addition Levels And Ratios On Production And Reproductive Performance Of Dairy Cows

The main purpose of this paper was to study the effects of different levels and proportions of fat sources on production and reproductive performance of dairy cows.To provide theoretical basis for the application of rumen protected fat and flaxseed in dairy production and reproduction.Experiment 1 Effects of different fat source addition levels and ratios on production performance of dairy cows.Forty-two Holstein cows with similar delivery dates and parity were selected as experimental animals,and the whole plant of corn silage,alfalfa hay and concentrate supplements were used as basic diets.Three types of fats were added to the basic diet,namely,rumen protected saturated fat,rumen protected unsaturated fat and flaxseed.The addition levels were 4 % and 5 % of dry matter intake,and the addition ratios of rumen protected fat and flaxseed oil(Form addition of flaxseed)were 100/0,70/30 and 55/45,respectively.A total of seven groups were set,which were represented by fat addition level(%)/different ratios of fat: 1)0/0 group,without adding fat;2)4/100 group,4% level,rumen protected saturated fat and flax oil ratio was 100/0;3)4/70 group: 4% level,rumen protected unsaturated fat and flax oil ratio was70/30;4)4/55 group: 4% level,rumen protected unsaturated fat and flax oil ratio was 55/45;5)5/100 group,5% level,rumen protected saturated fat and flax oil ratio was 100/0;6)5/70 group : 5% level,rumen protected unsaturated fat and flax oil ratio was 70/30;7)5/55 group: 5% level,rumen protected unsaturated fat and flax oil ratio was 55/45.The results showed that: 1)Compared with the 0/0 group,the 5/55 group very significantly reduced the DMI of cows(P<0.01);The 100/0 and 70/30 fat group significantly increased milk yield and FCM yield of dairy cows(P<0.05).2)The milk fat yield and total solid yield of70/30 fat group was significantly higher than that of 0/0 group and 55/45 fat group(P<0.05);The milk protein rate of 5% fat group was very signficantly higher than that in 0/0 group(P<0.01).SCC in 4% and5% fat groups was significantly lower than that in 0/0 group(P<0.05),SCC in 100/0 and 55/45 fat groups was significantly lower than that in 0/0 group(P<0.05).3)AST in 4/100 group was very significantly higher than that in 4/55 group and 5/100 group(P<0.01),and was significantly higher than that in 0/0 group(P<0.05).4)Adding different fat decreased serum BHBA content,but there was no significant difference among the groups(P>0.05);The serum triglyceride(TG)content in 4% fat group was significantly higher than that in 5% fat group(P<0.05).5)The apparent digestibility of crude fat(EE)in55/45 fat group was significantly higher than that in 100/0 fat group(P<0.05).6)Adding different fat sources can relieving weight loss,but there was no significant difference between the groups(P>0.05).In conclusion,adding different fat sources can increase milk yield,reduce SCC and weight loss in dairy cows.Experiment 2 Effects of different fat source addition levels and ratios on reproductive performance of dairy cowsTest groups were the same as test 1.The results showed that: 1)In the estrus duration of dairy cows,The serum estradiol(E2)content in 5/100 group was significantly higher than that in 5/55 group(P<0.01),significantly higher than that in 5/70 group(P<0.05),and that in 4/70 group was significantly higher than that in 5/55 group(P<0.05).PGE2 content in 4/100 group was significantly lower than that in 4/55 group(P<0.05).4/55 group significantly increased serum insulin-like growth factor content(P<0.05).2)During ovulation,PROG contents in 5/70 group were significantly lower than those in 0/0 group(P<0.05);PGE2content in 4/55 group was significantly higher than that in 0/0 group(P<0.05).3)At the maximum luteal phase,the serum LH content in 55/45 fat group was significantly lower than that in 0/0 group(P<0.05).Serum E2 content in 100/0 fat group was significantly lower than that in 0/0 group(P<0.05).FSH content in 5% fat group was very significantly higher than that in 0/0 group(P<0.01).Compared with the 0/0 group,The serum levels of PROG and TGF-β were significantly decreased in 4/100 group(P<0.05).4)The first estrus time of dairy cows in fat-added group was earlier than that in 0/0 group,but there was no significant difference among the groups(P>0.05).The total conception rate of dairy cows in 70/30 fat group and 55/45 fat group was higher than that in 100/0 group and 0/0 group.In conclusion,adding different fat sources can improve the reproductive performance of dairy cows,and 70/30 and 55/45 groups had higher total conception rate.