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研究生:陳美洙
研究生(外文):Mei Chu Chen
論文名稱:泌乳牛乳中尿素氮與其乳成分、理化性狀相關性之研究
論文名稱(外文):A study on the relationships among milk urea nitrogen, milk composition and physicochemical properties for lactating dairy cows
指導教授:黃珠芳
指導教授(外文):Chu Fang Huang
學位類別:碩士
校院名稱:國立屏東科技大學
系所名稱:畜產系
學門:農業科學學門
學類:畜牧學類
論文種類:學術論文
論文出版年:2002
畢業學年度:90
語文別:中文
論文頁數:111
中文關鍵詞:乳中尿素氮乳成分理化性狀
外文關鍵詞:milk urea nitrogenmilk compositionphysicochemical properties
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乳中尿素氮(milk urea nitrogen, MUN)含量為監控乳牛蛋白質與能量利用是否平衡的項目之一,然而影響乳中尿素氮測試結果的原因眾多。因此本研究目的為探討不同乳中尿素氮濃度與其他乳成分、理化性狀之相關性。
試驗材料取自嘉義、台南一帶牧場之乳牛,主要為分析各牧場泌乳牛乳中尿素氮濃度、乳成分與其理化性狀,並記錄泌乳牛胎次、泌乳天數、產乳量,且比較總乳、個別乳與不同測試方法之乳中尿素氮含量差異,所得到之結果如下:
Sigma-640分析值之廻歸方程式中,Sigma-640將受到乳蛋白質含量與胎次影響 ; 滴定酸度則受到乳蛋白質含量、乳糖含量、體細胞數及胎次等變數的影響;酒精試驗陽性乳將受到泌乳天數、胎次等變數的影響。
牛群狀況與MUN方面;分群(grouping)與MUN呈極顯著正相關(P < 0.001),泌乳天數與MUN呈顯著正相關(P < 0.05),胎次與MUN呈非常顯著負相關(P<0.01)。不論以Sigma-535(P<0.05)或Sigma-640(P<0.001)所測得的MUN值,初產牛皆明顯地高於經產牛。不論使用Sigma-535(P<0.001)或Sigma-640(P<0.05)所測得之MUN值皆以泌乳前期顯著低於泌乳中期與泌乳後期,惟泌乳中期與泌乳後期兩者則無顯著差異。利用Sigma-535所測得之值,以早乳之MUN值明顯地(P<0.01)高於晚乳。
MUN與乳成分相關性方面,MUN(Sigma-535)與蛋白質(r = 0.180, P < 0.001)、總固形物(r = 0.131, P < 0.01)、無脂固形物(r = 0.126, P < 0.01)呈正相關;Sigma-640的結果則與Sigma-535的分析值相似。
牛乳理化性狀與MUN之相關性方面;本試驗中滴定酸度測定分為 1).加等量水稀釋;2).不加等量水稀釋。MUN (Sigma-535)與滴定酸度呈正相關(加水r = 0.124,P < 0.01;不加水 r = 0.126, P < 0.01)。滴定酸度與胎次、產乳量、蛋白質、乳糖、體細胞數呈正相關;酒精試驗則與泌乳天數、胎次、產乳量、蛋白質呈正相關。酸度加水與否會影響所測得之滴定酸度值,兩者呈高度正相關(r = 0.94)。
試驗得知利用Sigma-640測定MUN時,脫脂與未脫脂處理兩者呈極顯著差異(P < 0.001)。在脫脂處理中,總乳的平均值為12.07 ± 3.52 mg/dL;個別乳的平均值為14.60 ± 2.98 mg/dL,兩者呈極顯著差異(P < 0.001)。乳中尿素氮不同分析方法之比較中,不論總乳或個別乳之乳中尿素氮含量,皆以Sigma-640分析法(未脫脂)之數值最高(分別為23.45±4.76 ; 20.07±4.73 mg/dL),接著為Azotest(分別為18.49±4.77;15.91±4.78 mg/dL)與Sigma-640(脫脂)(分別為12.07±3.52;14.61±2.98 mg/dL)分析法,而Sigma-535分析法之數值最低(分別為10.79±2.32;8.15±2.26 mg/dL),三種分析方法數值差異極顯著(P<0.001)。
Milk urea nitrogen (MUN) is used as an indicator of the protein-energy balance and for monitoring nutrition of dairy cows. Many factors can affect MUN concentration. The purpose of this study was to investigate the relationships among milk urea nitrogen, milk composition and physicochemical properties.
Milk samples were taken from Chiayi and Tainan county for analysis of MUN concentrations, milk composition and milk physicochemical properties. Individual cow information (includes parity, days in milk and milk yield) were recorded at each sampling. MUN concentrations of bulk tank and individual cow milk were also tested. Three urea nitrogen reagents (Sigma-535, Sigma-640 and Azotest dipstick) were used in this study. The results were as follows:
Regression equation analysis showed MUN concentrations (Sigma-640) affected by milk protein and parity. Titratable acidity (with or without water dilution) affected by milk protein, somatic cell counts and parity. Alcohol test positive milk affected by days in milk and parity.
Relationships with dairy herds information and MUN concentrations showed that MUN concentrations were significant positively related (P<0.001) to grouping; positively related (P<0.05) to days in milk; negatively related (P<0.01) to parity. In both Sigma-535 and Sigma-640, the MUN concentrations of primiparous cows were significant (P<0.05 ; P<0.001, respectively) higher then those for multiparous cows. The MUN concentrations (both Sigma-535 and Sigma-640) showed the lowest in the early lactation stage; there was no difference between the mid lactation and late lactation stage. MUN concentrations sampled in the morning were significant (P<0.01) higher than afternoon milking with Sigma-535.
The relationships of milk composition to MUN concentrations showed that MUN concentrations were positively related to milk protein(r = 0.180, P < 0.001), total solids(r = 0.131, P < 0.01) and solids nonfat (r = 0.126, P < 0.01). The results for Sigma-640 and Sigma-535 were similar.
The relationships of milk physicochemical properties to MUN concentrations showed that MUN concentrations (Sigma-535) were positively related (P<0.01) to titratable acidity, regardless of dilution with H2O or not. Diluted titratable acidity was positively related (P<0.001) to undiluted titratable acidity. Diluted or not, titratable acidity was positively related to parity, milk protein, milk yield, lactose and SCC. Alcohol test was positively related to days to lactation, parity, milk yield and milk protein.
When Sigma-640 was used, the MUN concentrations with un-defatted and defatted bulk tank milk or individual milk samples showed significant difference (P<0.001). MUN concentrations of the defatted bulk tank and individual milk samples with sigma-640 were 12.07 ± 3.52 mg/dL and 14.6 ± 2.98 mg/dL, respectively. MUN concentrations of the un-defatted bulk tank and individual milk samples with Sigma-640 were 23.45 ± 4.76 and 20.07 ± 4.73 mg/dL, respectively. For Sigma-535, the MUN concentrations of the defatted bulk tank and individual milk samples were 10.79 ± 2.32 and 8.18 ± 2.23 mg/dL, respectively. The MUN concentrations of Azotest in the bulk tank and individual milk samples were 18.49 ± 4.77 and 15.91 ±4.78 mg/dL, respectively. The results indicated that the MUN concentrations with Sigma-640 (un-defatted) was significantly(P<0.001) higher than those of Azotest, Sigma-640 (defatted) and Sigma-535.
中文摘要……………………………………………………………I
英文摘要………………………………………………………….IV
誌謝……………………………………………………………VII
目錄……………………………………………………………...IX
圖次索引………………………………………………………... .XV
表次索引……………………………………………………XVI
壹、緒言……………………………………………………………1
貮、文獻探討………………………………………………………3
一、泌乳牛蛋白質代謝……………………………………….3
(一) 瘤胃蛋白質代謝……………………….…………..3
(二) 肝臟代謝與尿素循環………………….…………..4
(三) 氨的毒性……………………………….…………..6
1. 氨對瘤胃的傷害………………………..……….6
2. 氨對牛蹄的傷害……………………………..….9
(四) 乳蛋白合成……………………………..………….9
二、蛋白質與尿素氮之關係…………………………………11
(一) 乳中尿素氮(MUN)取代全血尿素氮的優勢與
理想值…………………………………………..…13
(二) 全血尿素氮與乳中尿素氮濃度高低之意義.…....15
(三) 測定乳中尿素氮之時機……..…………….……..15
三、MUN與泌乳牛繁殖性能之關係………………………16
(一) 高蛋白質日糧與低繁殖性能之關係…….………16
(二) 高蛋白質日糧造成繁殖性能低下之機制….…. . .16
1. 機制1…………………………………………..17
2. 機制2…………………………………………..17
3. 機制3…………………………………………..18
四、影響MUN的因素……………………………………..19
(一) 樣品的採集時間與每日變化…………..………...19
(二) 日糧中蛋白質與熱能比…………….……………20
(三) 日糧中粗蛋白質、可降解蛋白(DIP)、不可降
解蛋白(UIP)與牛乳中含氮量的關係….…….......23
1. 日糧粗蛋白質含量與MUN之關係………….23
2. 可降解蛋白(DIP)、不可降解蛋白質(UIP)
與MUN之關係…………………...…………….23
(四) 產後間距(postpartum interval)、胎次(parity)與
尿素氮之關係…………………………….............24
(五) 產乳量與MUN之關係………………………25
(六) 個別乳(individual milk)、總乳(bulk tank milk)
與MUN之關係………………………………......26
(七) 乳成分與MUN之關係…………………………..27
(八) 測試方法………………………………………….28
1. 分光光度計法(colorimetric methods)…………..28
(1). 1,4-paradimethylaminobenzaldehyde(DMAB)
method………………………………………..28
(2).1diacetylmonoxime(DAM)method(Sigma-535)…28
2. 酵素法(enzymatic method)(Sigma-640)……….. 29
3. Azotest method…………………………….…..30
4. 其他分析法……………………………………..30
(九) 樣品的保存……………………………………….31
(十) 其他……………………………………………….31
五、牛乳理化性狀與乳品質之關係………………………..32
(一) 酒精不安定乳………………………………….…32
1. 高酸度酒精不安定乳…………………………. ..33
2. 低酸度酒精不安定乳…………………………...33
3. 酒精不安定乳鈣離子、urea、pH、不同泌乳
階段之關係……………………………………...34
(1). 鈣離子……………………………………...34
(2). 尿素………………………………………...35
(3). pH值……………………………………….36
(4). 泌乳階段…………………………………...36
(二) 滴定酸度(titratable acidity)...………………….…37
1. 滴定酸度………………………….……………..37
2. 滴定酸度與pH值之關係……………………….38
3. 影響牛乳滴定酸度之因素 ……………………... 38
(1). 乳成分對牛乳酸度之影響………………….38
(2). 泌乳期、胎次、季節對牛乳酸度之影響….40
參、材料與方法…………………………………………………..41
一、試驗材料………………………………………………..41
二、分析項目………………………………………………..42
(一) 滴定酸度(titratable acidity)……..……………..42
1. 加等量水滴定…………………………………...42
2. 不加水滴定……………………………………...43
(二) pH值……………………………………………..43
(三) 酒精試驗………………………………………….43
(四) 乳成分…….………………………………………43
(五) 體細胞數………………………………………….44
(六) 乳中尿素氮…….…………………………………47
1. Sigma-535分析法……………………………….47
(1). 標準曲線建立………………………………47
(2). 分析步驟………………………………...…47
2. Sigma-640分析法………………………………47
(1). 標準曲線建立……………………………...47
(2). 分析步驟…………………………………...48
a. 脫脂處理…………………………………..48
b. 未脫脂處理………………………………..48
3. Azotest 試紙法………………………………….53
三、統計分析………………………………………………..55
肆、結果與討論………………………………………………….57
一、MUN與理化性狀之變數………………………………57
(一) Sigma-640分析值之變數…………..…………....57
(二) 滴定酸度加水與否之變數……………………….58
1. 滴定酸度(加水)…………………………………58
2. 滴定酸度(不加水)………………………………60
(三) 影響酒精試驗之變數…………………………….61
二、牛群狀況與MUN之關係………………………………62
(一) 泌乳牛不同胎次、泌乳階段對MUN之影響…..64
(二) 不同分群泌乳牛對MUN之影響………………..68
(三) 樣品採集時間對MUN之影響…………………..70
(四) 產乳量對MUN之影響…………………………..73
三、MUN與乳成分之相關性………………………………75
四、牛乳理化性狀與MUN之相關性………………………77
五、以不同分析法測定總乳與個別乳對乳中尿素氮之
影響……………………………………...……………..80
(一) 總乳與個別乳脫脂與否對乳中尿素氮之影響….80
(二) 不同分析方法測定乳中尿素氮之比較……….…82
(三) 不同乳廠總乳乳中尿素氮含量之比較……….…85
伍、結論…………………………………………………………..87
陸、參考文獻……………………………………………………..89
柒、附錄………………………………………………………….109
作者簡介…………………………………..…………………… .111
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