Effects Of Two Typical Diets On Milk Yield, Milk Quality And Lactation Hormones Concentration In Dairy Cow

Although our country is one of the largest milk producers, China’sper capita consumption is only a quarter of the world average and thestandard of raw milk, milk fat and milk protein content was significantlylower than developed countries. The low quality of raw milk is the mainreason for low quality of domestic dairy products. Dairy breed, type ofdiet and environment are three important factors affecting milk quality,and diet is the most important. Modern physiology shows that varieties ofphysiological functions of the animal’s body are regulated by theneuroendocrine system. Mammary gland is the source of milk and it is atarget organ of a variety of hormones. Rumen as the special organs ofruminants, its microbial distribution is also influenced by neuroendocrinesystem. Based on the diet feeding status in our country, thesis designedtwo typical diets, high concentrate single straw group (CS) and low finematerial mixed roughage group (MF). The study is trying to find out theeffect of different daily ration on dairy cow lactation performance andmilk composition; and to detect lactation related hormone levels in thelactating dairy blood and rumen fluid. The purpose of this paper is toprovide a theoretical basis that key neuroendocrine factors have influenceon the mechanism of milk fat, milk protein synthesis in the two typicaldiets mode. The article includes the following three experiments.Experiment Ⅰ: Effects of different types of diets on lactating dairycows’ dry matter intake.Select20New Zealand’s first child healthyHolstein cows,10cows install rumen and duodenal cannula throughsurgery. According to the lactation performance and weight, twenty ofthem were randomly divided into two groups. Each group was randomlyassigned to five fistula cows and five non-fistula cows. The two types of diets, corn stalk group (CS) and mixed roughage group (MF), were fed.The experiment lasted for seven weeks, two weeks’ pre-feeding periodand five weeks’ feeding period. Record dry matter intake and bodycondition during the test. The results showed that dry matter intake weresignificant different in CS and MF group. It’s also have differences trendin body condition. Dry matter intake of MF group is16.3kg/d and the CSgroup is15.08kg/d. MF group was significantly higher than the CS group(P <0.01). After the experiment, the MF group cow body conditionstatistics is2.91and CS group is2.75. MF group is higher than the CS.But the difference was not significant (P>0.05).ExperimentⅡ: Study the impact of dairy quality and lactationperformance with different types of diet. Record each cow’s milkproduction every day and detect milk composition by compositionanalyzer at the same time. The result showed that the milk yield of MFgroup is21.15Kg/d and CS group is19.32Kg/d. Milk yield of MFgroup was significantly higher than the CS (P <0.01). milk-fat percentageof MF group is4.448%and the CS is4.230%. Milk protein rate is3.795%and3.731%; lactose rate is4.687%and4.660%; milk fat yield is0.937kg/d and0.811kg/d; milk protein yield were0.789kg/d and0.733kg/d respectively. Milk fat percentage, milk protein and fat yieldof MF group are very significantly higher than the CS group (P <0.01).The proportion of milk protein and lactose of MF group is higher than theCS group, but the difference was not significant (P>0.05).Experiment Ⅲ：Detect the lactation-related hormones concentrationof lactating dairy cows’ serum and10fistula dairy cows tumor gastricjuice under two different dietary conditions by radioimmunoassay andenzyme-linked immunosorbent. Promote adrenaline and leptin in theserum of the MF diet group and CS diets significantly different (P<0.05),Cortisol in the serum of MF diet group and CS diets significantlydifference(P <0.01), and the remaining hormone concentrationdifferences are not significant. Rumen fluid hormone concentrations were not significant different in MF diet group CS diet group.Analysis of milkprotein and milk fat between with hormones in sulin,insulin and milk fatpercentage is negatively correlated,corticotrophin releasing hormone waspositively related to milk fat,no significant correlation with otherhormones between with milk fat and milk protein.In summary, MF group diets significantly reduce cow serum cortisoland significantly improve adrenocorticotropic hormone and leptinsecretion levels. It did not significantly affect the hormone levels in therumen fluid. MF group significantly improve dry matter intake andenhance the quality of milk.