開發乳牛轉換期預防酮症與乳房炎之綜合型飼料添加物

Development of Supplement to Prevent Ketosis and Mastitis for Transition Cows

黃治達(Chih-Ta Huang)

指導教授 ： 徐濟泰

國立臺灣大學/生物資源暨農學院/動物科學技術學研究所/碩士(2017年)

https://doi.org/10.6342/NTU201702276

摘要

在乳牛分娩的前三週至後三週一般通稱為轉換期，這段期間乳牛除了須應付胎兒快速成長的營養需求，還需要應付產後泌乳造成的大量能量需求以及內分泌與環境變化造成的氧化壓力，再加上採食量於這期間往往會受到抑制而形成負能量平衡及免疫力下降等諸多問題。因此轉換期乳牛常發生酮症、皺胃異位、胎衣滯留、感染性疾病 (乳房炎及子宮炎等)以及繁殖表現下降等，故如何預防乳牛在轉換期健康狀況受到劇烈影響已經成為一個重要的課題。
　　本試驗總共分成兩個階段，旨在探討自行設計之綜合型添加物於轉換期給予乳牛額外補充，以發揮對於酮症、乳房炎及其他負面影響之預防潛力。第一階段的試驗以胎次將實驗牛群分成初產牛及經產牛，再以是否餵食添加物分成對照組及實驗組。綜合型添加物主要以丙二醇及甘油製成之粉末與維生素A、D、E及硒混合而成，實驗組的牛隻於分娩前三週開始每日餵食定量混合添加物至分娩後三週停止；而對照組則不改變原有飼養方式且不餵食添加物。檢測項目包含分娩當日及分娩後第1、2及3週之血糖、血液游離脂肪酸 (NEFA) 及β-羥基丁酸，還有試驗終止當日之乳產量及乳成份，此外還記錄分娩後至第一次做人工授精的間期及其他疾病資料。由於第一階段的試驗發現在初產牛有較顯著的試驗效益，故第二階段的試驗只鎖定初產牛，並以體態評分 3.5將牛隻分成胖的牛群及瘦的牛群，再分別細分為實驗組及對照組。試驗進行及採樣項目與方式比照第一階段，但在分娩前三週多加一次血樣採集作為試驗起始資料，且於試驗起初及試驗終止時各測定一次體態評分，以此來探討設計之添加物對不同體態的牛隻造成效益異同。
　　試驗發現初產牛在轉換期發生的負能量平衡情形會較經產牛嚴重，可能是因為初產牛除了須應付轉換期壓力之外還須額外應付自身成長所需能量，且在牛隻未分群的情況下，體型小之初產牛容易受到體型大之經產牛欺負而影響採食。在綜合型添加物額外補充下可從血液生化值發現負能量平衡的情形改善、乳產量增加、乳蛋白及非乳脂固形物上升及分娩後至第一次人工授精間期縮短的現象，雖改善項目未達顯著差異，但卻有一致改善的現象且改善效益在初產牛較為明顯。第二階段的試驗發現血液生化值的資料在瘦的牛群組別中，顯示負能量平衡較胖的牛群嚴重而與文獻相牴觸，很可能是因為分娩後牛隻未分群造成的競爭行為，導致肢體損傷及採食意願低落造成的。從血液生化值、乳成份及體組成流失上發現綜合型添加物對牛隻健康狀況的改善於胖的牛隻上較為明顯，但胖的牛隻因為在轉換期流失較多體態評分故在繁殖表現上改善效益並不明顯。本試驗合作之乳牛場在原本的飼料中已經有額外添加了足量的維生素A、D、E及硒，故在試驗中看不到本試驗設計之綜合型添加物對乳房炎產生預防的效果。
　　綜合試驗發現，轉換期乳牛於分娩後的分群十分重要，可以避免不必要的競爭行為，此外還需要嚴加控制乳牛分娩前的體態評分以避免繁殖表現下降。於轉換期額外補充此綜合型添加物可以改善負能量平衡並降低酮症發生的風險、提升乳產量、改善乳品質及改善繁殖表現。

關鍵字

乳牛 ； 轉換期 ； 酮症 ； 乳房炎 ； 初產牛 ； 經產牛 ； 體態評分

並列摘要

Period from 3 weeks before to 3 weeks after parturition is usually called transition period. In this period, dairy cows will inevitably face lots of health problems like ketosis, mastitis, retained placenta, displaced abomasum and so on. The reasons are negative energy balance and decreasing concentrations of many trace elements due to decreasing dry matter intake and increasing energy demand caused by growing fetus and lactation. Therefore, how to help dairy cows get through transition period safely has become an important issue.
　　The objective of this experiment was to investigate the effects of supplementing transition dairy cows with experimental additives to prevent ketosis and mastitis. Experiment was divided into 2 parts. Treatment group was daily supplemented with additives consisted of Vit. A, D, E, Se and powder made from glycerol and propylene glycol from 3 weeks before to 3 weeks after calving. Blood samples were collected on the day right after calving and 1, 2 and 3 week after calving. Milk samples were collected on the day of 3 week after calving. Besides, daily milk yield, days from calving to first AI and health information were recorded. Experiment I was aimed at the difference between primiparity and multiparity, and experiment II was aimed at primiparity with different body condition score (BCS) due to supplementation effects on primiparity were more obvious in experiment I.
　　Results showed that primiparity faced more severe negative energy balance than multiparity did. There were improvements in negative energy balance, milk yield, milk components and reproductive performance when cows are supplemented with experimental additives. Although there was no statistically significant difference, but the effects were more obvious and consistent in primiparity. Results of experiment II showed that cows with lower BCS faced more severe negative energy balance than cows with higher BCS according to blood parameters. This finding is different from literatures, and the reason may be related to the feeding competition among cows with different body sizes. Although there was no significant difference, but there were improvements in negative energy balance, milk components and loss of BCS in cows with higher BCS. As to reproductive performance, improvement in cows with lower BCS was more obvious than cows with higher BCS. There was no obvious effect of preventing mastitis in experiment I and II due to high dose of trace elements in original daily rations of dairy farms.
　　 In conclusion, grouping in farms during transition period is important to prevent inevitable feeding competition among cows, and it will be easier to provide proper management to different groups of cows. In addition to this, supplementation with experimental additives can help alleviating negative energy balance and improving milk yield, milk composition and reproductive performance.

並列關鍵字

Dairy cows ； Transition period ； Ketosis ； Mastitis ； Primiparity ； Multiparity ； Body condition score

參考文獻

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