同期化處理對改善熱季荷蘭乳牛懷孕率之效果

本試驗之目的在探討藉由外源性內泌素同期化處理對改善熱季荷蘭乳牛繁殖效率之效果。試驗於5月至10月份的熱季分批執行，排卵同期化處理組（RH組）為牛隻分別於第1天、第8天及第10天肌肉注射激性腺素釋素（GnRH）、前列腺素（PGF_(2α)）及GnRH，並在處理後觀察發情及進行人工授精；發情同期化處理組（PG組）牛隻經注射PGF_(2α)後未見發情者，於第11至14天後再注射一劑PGF_(2α)；對照組牛隻則採人工觀察發情及人工授精，不施打任何外源性內泌素。每次將可供試驗的經產牛隻逢機編入對照組、PG組或RH組，而女牛則逢機分入對照組或PG組，全部試驗共使用荷蘭經產牛116頭次及女牛88頭次。試驗結果顯示，在經產牛方面，對照組、PG組及RH組的熱季懷孕率分別為13.6%（6/44）、27.5%（11/40）與28.1%（9/32），三組之差異並不顯著，但若以平均值作比較，則以兩組外源性內泌素處理者有提升熱季乳牛繁殖效率達14.2%的趨勢；在女牛方面，藉由PGF_(2α)處理並無改善效果，其在熱季之懷孕率為48.7%（19/39），與對照組之44.9%（22/49）相近。另於涼熱季各選擇約10頭經產牛，於配種日後42天內每週採血一次，檢測其血清助孕酮濃度，結果顯示涼季懷孕之經產牛在第21天之血清助孕酮濃度為12.27ng/mL，顯著高於熱季懷孕經產牛之7.87ng/mL（P＜0.01）。綜合上述，熱季期間牛隻利用發情同期化及排卵同期化處理後再授精之懷孕率，雖與自然發情後再授精之懷孕率，二者間並無顯著差異，但是同期化處理可監控牛隻的發情、方便繁殖管理。

關鍵字

懷孕率；乳牛；熱季；同期化

並列摘要

The experinent used exogenous hormone, GnRH and PGF_(2α), to synchronize ovulation and/or estrus to improve the conception rates. Trials were conducted during the hot season from May to Oct. Cows assigned into ovulation synchronization group (RH) were administered one injection of GnRH, PGF_(2α), and GnRH on day 1, 8, and 10, respectively. Artificial insemination (AI) was applied on day 11 to 12 after heat detection. Cows and heifers in synchronized estrus group (PG) were administered one PGF_(2α) injection and the second injection was on day 11 to 14, if the cows were not in heat. Cows in control group were not administered with hormone and were not observed for their natural estrus cycle. A total of 116 cows and 88 heifers were used. Results indicated that the conception rates of cows in control, PG, and RH groups were 13.6% (6/44), 27.5% (11/40), and 28.1% (9/32), respectively. Numerically, two hormone treatment had the same tendency to improve the conception rates for 14.2% when compared with the control group. There was no effect from exogenous hormone treatment on conception treatment in heifers. Conception rates were 44.9% (22/49) and 48.7% (19/39) for control and PG group. Blood sampled were taken from 10 cows in both seasons weekly until day 42 after AI. Serum progesterone levels on day 21 of cows in cool season (12.27 ng/mL) were higher than those in hot season (7.87 ng/mL) (P ＜ 0.01). In summary, there is no difference on conceptionrate either estrus or ovulation synchronization groups or natural heat detection group during hot season. However, estrus or ovulation synchronization can help the heat detection and reproductive management of cows.

並列關鍵字

Conception rate ； Dairy cattle ； Hot season ； Synchronization

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