Effects Of Cysteamine Hydrochloride In The Diets Of Mid-lactating Dairy Cow

This study was aimed at determining the safe dose of CysteamineHydrochloride(CSH) as additive in lactating cow. We researched the effects of CSHon production performance, blood parameters, body condition and nutrients apparentdigestibility of dairy cow.48healthy Holstein cows(average DIM=123d, average milkyield=27kg/d, average parity=1.2)were randomly divided into4groups(12cows/group)according to principle of similar milk yield, DIM and parity. During the entireexperiment, cows in4groups(one control group and three treatment groups) were feda basal diet supplemented with0,3,15,30g/kg·concentrates CSH. Feeding experimenthas been run three period (2-wk adaptation period,2-wk standardization period,9-wkformal experiment period). All cows were housed in free stall barn and received freeaccess to water and diet. Cows were milked3times daily(5:00,13:00,21:00) and fed3times daily(6:30,13:30,18:30) with total mixed ration(TMR).1Effects of Cysteamine Hydrochloride on production performance of dairy cowDry matter intake was significantly increased by adding3g/kg and15g/kgCysteamine Hydrochloride compared to the control group(P<0.05), meanwhile, it hada lower trend when adding30g/kg Cysteamine Hydrochloride; Milk yield,4%fatcorrected milk and energy corrected milk were significantly increased of cows givenCysteamine Hydrochloride, and the best dose was3g/kg Cysteamine Hydrochloride;Cows given3g/kg Cysteamine Hydrochloride had a higher fat percentage and proteinpercentage in milk(P<0.05), and milk lactose percentage was higher of cows fed15g/kg Cysteamine Hydrochloride (P<0.01).2Effects of Cysteamine Hydrochloride on blood parameters of dairy cowThe levels of serum alanine aminotransferase (ALT), aspartate aminotransferase(AST), alkaline phosphatase (ALP) and creatine kinase (CK) were increased linearlysignificant with increasing dietary Cysteamine Hydrochloride supplementation(P<0.01). By comparing with the control group, the levels of serum ALT and CKrespectively increased9.51%and22.79%after cows given30g/kg Cysteamine Hydrochloride (P<0.05,P<0.01). The levels of ALP respectively improved18.74%,28.96%and29.61%of cows fed3g/kg,15g/kg and30g/kg CysteamineHydrochloride compared with the control group (P<0.01).30g/kg Cysteamine Hydrochloride in the diet significantly improved theconcentration of white blood cell, Lymphocyte, Granulocyte, Intermediate cell andIntermediate cell percentage (P<0.05,P<0.05,P<0.05,P<0.01,P<0.01), and decreasedthe concentration of red blood cell (P<0.01).The activities of serum superoxide dismutase increased linearly significant withincreasing dietary Cysteamine Hydrochloride supplementation(P<0.05),and theconcentration of malonaldehyde decreased(P<0.01).3g/kg Cysteamine Hydrochloridein the diet significantly improved the levels of total antioxidant capacity (P<0.01).The activities of Glutathione peroxidase and levels of total antioxidant capacity weresignificantly decreased by Cysteamine Hydrochloride supplementation.30g/kg Cysteamine Hydrochloride in the diet significantly decreased the levelsof cortisol (P<0.01); The levels of somatostatin decreased linearly significant withincreasing dietary Cysteamine Hydrochloride supplementation(P<0.05);3g/kg and15g/kg Cysteamine Hydrochloride in cow’s diet respectively decreased theconcentration of serum T4by15.50%and14.85%(P<0.01).3Effects of Cysteamine Hydrochloride on nutrients apparent digestibility ofdairy cow15g/kg Cysteamine Hydrochloride in cow’s diet significantly improved theapparent digestibility of ADF (P<0.05). The apparent digestibility of dry matter,crude protein, ether extract, NDF and organic matter had a higher trend after feedingCysteamine Hydrochloride.4Effects of Cysteamine Hydrochloride on clinical indexes of dairy cowCows were in the heat stress environment in the first4weeks of the formalexperiment period on account of temperature-humidity index was greater than72.And there was no significant differences of temperature-humidity index between4 groups. The respiratory rate and rectal temperature decreased linearly significant withincreasing dietary Cysteamine Hydrochloride supplementation (P<0.01,P<0.01). Theaddition of15g/kg and30g/kg Cysteamine Hydrochloride in diets significantlydecreased the respiratory rate and rectal temperature compared with control group(P<0.01,P<0.01). There was no significant differences of body condition and bodyweight after feeding Cysteamine Hydrochloride.