Sauls J A, Voelz B E, Mendonça L G D, Stevenson J S
Department of Animal Sciences and Industry, Kansas State University, Manhattan, KS, 66506-0201, USA.
Department of Animal Sciences and Industry, Kansas State University, Manhattan, KS, 66506-0201, USA.
Theriogenology. 2018 Apr 1;110:27-33. doi: 10.1016/j.theriogenology.2017.12.051. Epub 2018 Jan 3.
Two experiments were performed to test the hypothesis that administering PGF concurrent with timed artificial insemination (AI) in lactating dairy cows would enhance pregnancy per AI (P/AI). In experiment 1, lactating Holstein cows (n = 289) in one herd were enrolled after a non-pregnancy diagnosis (30-36 d after AI) to synchronize subsequent ovulation before AI. Cows were assigned randomly to receive (im) 10 mg of PGF concurrent with timed AI (Day 0; treatment) or no injection (control). Blood samples were collected on Days -3, 0, and 13 to determine serum concentrations of progesterone. Ovaries were scanned via transrectal ultrasonography to determine follicle diameters (Day -3), subsequent ovulation risk (Day 13), and total volume of luteal tissue (Day 13). Diagnosis of pregnancy occurred on Days 32 and 80 after AI. Ovulation risk post-AI exceeded 90% and did not differ between treatments. In addition, PGF treatment only numerically increased progesterone (5.7 ± 0.3 vs. 6.2 ± 0.3 ng/mL) or luteal tissue volume (8.9 ± 0.4 vs. 9.8 ± 0.5 ng/mL) on Day 13 by 8.8% (P = .206) or 10.1% (P = .134) in control and treated cows, respectively. Pregnancy per AI at Days 32 (P = .50) and 80 (P = .33) did not differ between treatments. Cows with progesterone >0.5 ng/mL at timed AI had reduced (P < .001) ovulation risk but risk was unaffected by treatment. In experiment 2, lactating dairy cows (n = 1828) in two commercial dairy herds were enrolled at time of insemination (Day 0), and assigned randomly to treatment or control as described in experiment 1. Initial (Days 32-35) and confirmed (Days 63-68) pregnancy diagnosis revealed no differences in P/AI or pregnancy loss. Pregnancy diagnosis on Days 32-35 produced percentage increases in P/AI for primiparous compared with multiparous cows (20.8%; P = .002), for first-service compared with repeat-service cows (26%; P = .001), and cows in one herd compared with the second herd (36%; P < .001). Pregnancy loss was greater (P = .001) for cows inseminated at first (10.0%) vs. later services (5.3%) but was unaffected by treatment. Cows treated with PGF in one herd produced more twins than control cows (11.7 vs. 3.2%), whereas no treatment difference was detected in the second herd (5.6 vs. 5.6%), respectively. We conclude that im treatment of lactating dairy cows with 10 mg of PGF concurrent with timed AI did not improve P/AI or embryo survival, but increased twinning in one herd.
进行了两项实验，以检验在泌乳奶牛定时人工授精（AI）的同时给予前列腺素F2α（PGF）会提高每次人工授精的妊娠率（P/AI）这一假设。在实验1中，一个牛群中的泌乳荷斯坦奶牛（n = 289头）在非妊娠诊断（人工授精后30 - 36天）后被纳入，以便在人工授精前同步后续排卵。奶牛被随机分配接受（肌肉注射）10毫克PGF并同时进行定时人工授精（第0天；处理组）或不注射（对照组）。在第 -3、0和13天采集血样，以测定血清孕酮浓度。通过经直肠超声扫描卵巢，以确定卵泡直径（第 -3天）、后续排卵风险（第13天）和黄体组织总体积（第13天）。在人工授精后第32天和第80天进行妊娠诊断。人工授精后的排卵风险超过90%，且处理组之间无差异。此外，PGF处理仅使第13天的孕酮（5.7±0.3对6.2±0.3纳克/毫升）或黄体组织体积（8.9±0.4对9.8±0.5纳克/毫升）在数值上分别增加了8.8%（P = 0.206）或10.1%（P = 0.134），对照组和处理组奶牛之间无显著差异。在第32天（P = 0.50）和第80天（P = 0.33），处理组之间的每次人工授精妊娠率无差异。定时人工授精时孕酮>0.5纳克/毫升的奶牛排卵风险降低（P < 0.001），但风险不受处理影响。在实验2中，两个商业奶牛群中的泌乳奶牛（n = 1828头）在授精时（第0天）被纳入，并如实验1中所述随机分配到处理组或对照组。初始（第32 - 35天）和确诊（第63 - 68天）妊娠诊断显示，每次人工授精妊娠率或妊娠丢失率无差异。第32 - 35天的妊娠诊断显示，初产奶牛与经产奶牛相比，每次人工授精妊娠率的百分比增加（20.8%；P = 0.002），首次输精奶牛与重复输精奶牛相比（26%；P = 0.001），以及一个牛群中的奶牛与第二个牛群中的奶牛相比（36%；P < 0.001）。首次输精奶牛的妊娠丢失率高于（P = 0.001）后续输精奶牛（10.0%对5.3%），但不受处理影响。一个牛群中接受PGF处理的奶牛双胎率高于对照组奶牛（11.7%对3.2%），而在第二个牛群中未检测到处理差异（5.6%对5.6%）。我们得出结论，在泌乳奶牛定时人工授精的同时肌肉注射10毫克PGF并不能提高每次人工授精妊娠率或胚胎存活率，但会增加一个牛群中的双胎率。
