The Effect Of Wheat Straw Replacing Alfalfa Hay On The Rumen Digestion And Metabolism And Lactation Performance In Dairy Cows

In this experiment,we replaced 0%,20%,40% and 60% alfalfa hay with wheat straw powder under isothermal and equal nitrogen conditions to investigate the effects on the rumen metabolism and production performance of lactating dairy cow.Under a large group of randomized block designs,60 cows were selected and divided into 4 groups.Four groups of cows were randomly fed with four different experimental diets: positive control group CG(0% replacement),experimental group AL(20% substitution),AM(40% substitution),AH(60% substitution).The prefeed period was 2 weeks and the trial period was 8 weeks.The feed intake of nutrients,dry matter intake,crude protein,acid detergent fiber,neutral detergent fiber and organic matter intake were all significantly affected by diet(P<0.05).Crude protein intake was highest in the AH group.There was a significant difference between the apparent digestibility of organic matter and crude protein(P<0.05).Among them,the dry matter digestibility of the AL group was the highest numerically,and the apparent digestibility of the crude protein of the wheat stalk maximum substitute group was significantly decreased(P<0.05).There were not significant difference between the apparent digestibility of dry matter,neutral detergent fibers and acidic detergent fibers(P>0.05).Nitrogen intake was significantly affected by diet(P<0.01).Intake of nitrogen in CG and AL groups was significantly higher than that of AM and AH groups(P<0.05).The ratios of milk nitrogen,fecal nitrogen,urine nitrogen and nitrogen uptake were not significantly different between groups(P>0.05).The differences of acetic acid,propionic acid,butyric acid,isobutyric acid,valeric acid,isovaleric acid and rumen pH were not significant(P>0.05).Milk yield,milk protein content,milk protein rate,lactose content,lactose rate,milk fat content and milk fat percentage were not affected by diets,and there was no significant difference between groups(P>0.05).The milk urea nitrogen content in the MH group was significantly lower than the other three groups(P<0.05).There was no significant difference in 4% standard milk,whole solids,energy correcting milk,net milking energy and feed efficiency due to diet(P>0.05).The differences among insulin,glucagon,growth hormone and cortisol were not significant(P>0.05).However,there was significant difference between insulin-like growth factor and prolactin(P<0.01).The serum levels of ?-hydroxybutyric acid,triglyceride and urea nitrogen were not significantly different(P>0.05).Glucose and volatile fatty acids in serum were significantly affected by diet(P<0.01).In the calculation of economic benefits,other costs(labor,machinery,etc.)were not considered in the aquaculture costs.Under the condition of the same costs among groups,the economic benefit obtained by the AL group was the largest.