Mialot J P, Ponsart C, Gipoulou C, Bihoreau J L, Roux M E, Deletang F
Ecole Vétérinaire d'Alfort-LEGSA, Maisons-Alfort, France.
Theriogenology. 1998 May;49(7):1353-63. doi: 10.1016/S0093-691X(98)00082-X.
The objective of this study was to determine the efficacy of PGF2 alpha treatment on pregnancy and calving rates in autumn-calving suckler beef cows synchronized with progesterone and eCG. The population studied consisted of 124 Charolais and 130 Limousin cows in 13 and 12 beef herds, respectively. In each herd, pairs of cows were formed according to parity, body condition score and calving difficulty. Group 1 received a progesterone releasing intravaginal device (PRID) for 12 d with a capsule containing 10 mg estradiol benzoate at implant insertion and 500 IU eCG at PRID removal (Day 0). Group 2 received the same treatment plus 25 mg i.m. dinoprost at Day -2. Each cow was artificially inseminated 56 h after PRID removal (Day 3). Plasma progesterone concentrations were measured to determine cyclicity prior to treatment in samples take on Days -22 and -12, to confirm the occurrence of ovulation (Day 13) and to determine the early pregnancy rate (Day 26). Serum pregnancy-specific protein B (PSPB) concentrations were determined to assess pregnancy rate at Day 39. The effects of variation factors on pregnancy and calving rates after treatment were studied using logistic mixed models and a Cox model, respectively. There were no significant differences between groups or breeds for the rate of cyclicity before treatment nor for ovulation rate (means, 74.1 and 95.7%, respectively). Cyclicity was, however, influenced by individual factors such as body condition score (OR = 3.36, P = 0.001), parity (OR = 5.4, P = 0.001) and herd factors such as stocking rate (OR = 5.62, P = 0.001). The use of a prostaglandin injection increased pregnancy rate at Day 26 (71.7 vs 56.7%, P = 0.01) and at 39 d (67.7 vs 54.3%, P = 0.02) and the calving rate at induced estrus (64.5 vs 48.5%, P = 0.01). We observed 9 twin calvings (5.6%) which occurred in cyclic cows only before treatment. Cows in Group 2 had a 1.5 greater chance of calving before 300 d following the first AI than cows in Group 1 (P = 0.03). In conclusion, the addition of PGF2 alpha injection, 48 h before PRID removal, increased reproductive efficiency in autumn-calving Charolais and Limousin suckler beef cows compared to a classical estrus synchronization treatment using a PRID + eCG.
本研究的目的是确定在使用孕酮和孕马血清促性腺激素（eCG）进行同期发情处理的秋季产犊的肉用母牛中，前列腺素F2α（PGF2α）处理对妊娠率和产犊率的影响。研究群体分别由13个和12个肉牛群中的124头夏洛来牛和130头利木赞牛组成。在每个牛群中，根据胎次、体况评分和产犊难度将母牛配对。第1组母牛接受含孕酮的阴道内缓释装置（PRID）12天，在植入时放入含10毫克苯甲酸雌二醇的胶囊，在取出PRID时（第0天）注射500国际单位的eCG。第2组接受相同处理，并在第 -2天肌肉注射25毫克氯前列醇。每头母牛在取出PRID后56小时（第3天）进行人工授精。在第 -22天和第 -12天采集样本测量血浆孕酮浓度以确定处理前的发情周期，在第13天确认排卵情况，并在第26天确定早期妊娠率。在第39天测定血清妊娠特异性蛋白B（PSPB）浓度以评估妊娠率。分别使用逻辑混合模型和Cox模型研究处理后变异因素对妊娠率和产犊率的影响。处理前两组之间以及不同品种之间的发情周期率和排卵率均无显著差异（平均值分别为74.1%和95.7%）。然而，发情周期受个体因素如体况评分（优势比=3.36，P = 0.001）、胎次（优势比=5.4，P = 0.001）以及群体因素如饲养密度（优势比=5.62，P = 0.001）的影响。注射前列腺素可提高第26天（71.7%对56.7%，P = 0.01）和第39天（67.7%对54.3%，P = 0.02）的妊娠率以及诱导发情时的产犊率（64.5%对48.5%，P = 0.01）。我们观察到9例双胎产犊（5.6%），均发生在处理前处于发情周期的母牛中。第2组母牛在首次人工授精后300天内产犊的可能性比第1组母牛高1.5倍（P = 0.03）。总之，与使用PRID + eCG的经典同期发情处理相比，在取出PRID前48小时添加PGF2α注射可提高秋季产犊的夏洛来和利木赞肉用母牛的繁殖效率。
