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中國畜牧學會會誌
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中文摘要
本研究目的為探討牛乳中尿素氮含量與繁殖性能之關聯性。試驗資料收集期間為 2015 年 1 至 12 月，以畜產試驗所新竹分所乳牛場飼養之頭產（n = 32）及二產（n = 27）泌乳牛為主， 並乳牛性能改良計畫（Dairy herd improvement, DHI）之乳產量及品質資料紀錄至少累計三次 以上；且以牛乳中尿素氮（Milk urea nitrogen, MUN）含量 10 mg/Dl 作為分界值，以了解牛 乳中尿素氮含量對於繁殖性能之影響。試驗結果顯示，頭產牛 MUN 介於 10-12 mg/dL 之牛 隻數為 12 頭，受胎率（Conception rate, CR%）及淘汰率（Mortality rate, MR%）分別為 33% 及 33%；MUN 介於 8-10 mg/dL 之牛隻數為 20 頭，CR 與 MR 分別為 30% 及 35%。二 產牛 MUN 介於 10-12 mg/dL 之牛隻數為 9 頭，CR 及 MR 分別為 30% 及 33%；MUN 介 於 8-10 mg/dL 之牛隻數為 18 頭，CR 與 MR 分別為 28% 及 50%。由上述結果可知，無 論頭產或二產泌乳牛群之 MUN 低於 10 mg/dL 的比例較高，此結果可能與泌乳牛群之飼糧 組成或分群管理有關，需再檢討改進。另外，MUN 介於 8-10 mg/dL 其牛群之受胎率較低且 被淘汰的比例也較高，此說明 MUN 含量低於 10 mg/dL 可能會造成受胎率下降，且較易離 群。因此，牛乳中尿素氮含量與受胎率有關聯性，且可作為推估繁殖性能表現之參考依據之一。
英文摘要
The purpose of this study was to evaluate the association between milk urea nitrogen (MUN) and fertility of dairy cows using field data. The data came from first lactation (n=32) and second lactation (n=27) dairy herd belonging to Livestock Research Institute Hsinchu Branch. Reproductive data and MUN measurements from cows that calved between January and December, 2015 that DHI recorded had been at least three times were included in the study. Animals were categorized into two based on MUN values in these data. The result shown that first lactation cows (n=12) with MUN levels between 10-12 mg/dL the conception rate and mortality rate was 33 % and 33 % respectively； The cows (n=20) with MUN levels between 8-10 mg/dL the CR and MR was 30 % and 35 % respectively. Second lactation cows (n=9) with MUN levels between 10-12 mg/dL the CR and MR was 33 % and 33 % respectively；The cows (n=18) with MUN levels between 8-10 mg/dL the CR and MR was 28 % and 50 % respectively. Regardless the number of lactation, the proportion of MUN less than 10 mg/dL were more than MUN higher than 10 mg/dL. That might relate to the dairy cows total mix ration composition and group management. In addition, MUN less than 10 mg/dL have lower CR and high MR. Our results indicate that MUN levels appear to be possibly related to dairy cow fertility and are associated with a high risk of mortality rate.