PDF《Theriogenology》

1 These authors are co-?rst authors. Contents lists available at ScienceDirect Theriogenology journal homepage: www.theriojournal.com 0093-691X/$ C see front matter ?

2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.theriogenology.2013.08.008 Theriogenology

80 (2013) 1074C1081 throughout the dairy and beef cattle industries, it may also produce reduced fertility if the technician improperly de- posits semen into the female reproductive tract. For example, deposition of frozen semen into the cervix rather than the uterine body increased retrograde loss of semen into the vagina with up to 60% of semen lost after place- ment in the cranial portion of the cervix [4]. Indeed, >

20% of inseminations resulted in semen being deposited into the cervix rather than the uterine body [4C6]. Deposition of semen into the uterine horns has been proposed as an alternative method to the traditional deposition into the uterine body. However, comparison of these two tech- niques has produced surprisingly variable results with re- ports of deep-horn AI having no effect [7C13] or improving [14C16] fertility in cattle. Fertilization rates in superovulated cows are generally lower than in nonsuperovulated cows [17]. Ova from superovulated cows, fertilized or unfertilized, have fewer accessory sperm, suggesting that low fertilization rates are a consequence of low numbers of viable sperm at the site of fertilization or altered ability for sperm penetration into oocytes of superovulated cows [17C20]. Many factors may contribute to a reduced fertilization rate in superovulated cows, including greater retrograde semen loss due to increased mucus, increased velocity of ova transport [21] suboptimal timing of semen deposition [22], changes in maturation of superovulated ova [23], an inappropriate hormonal environment altering gamete transport [21,23], dose of FSH used [24], LH content in the FSH preparation (Bender et al., unpublished data), FSH batch [25], stage of the estrous cycle when the superstimulation treatment begins [26], intervals after calving [18], AI technician skill, semen fertility [27], and type of semen [28C30]. Fertiliza- tion rate and therefore embryo production in super- ovulated cattle may be improved by optimizing the physiological conditions and techniques used during superstimulation protocols. Thus, our primary objective was to determine the effect of site of semen deposition in superovulated cows on fertilization rates and embryo quality. Our hypothesis was that fertilization rates of superovulated lactating dairy cows would increase when semen is deposited into the uterine horns compared with the uterine body. Our sec- ondary objective was to evaluate the impact of uterine environment (presence of subclinical endometritis) on fertilization rate and embryo quality. We hypothesized that cows with subclinical endometritis at the beginning of the superstimulation would have decreased fertilization rates and embryo quality. 2. Materials and methods 2.1. Supplies and semen Prostaglandin F2a (PGF2a;

Lutalyse,

25 mg of Dinoprost tromethamine/dose) was from P?zer Animal Health, NY, USAdexperiment

1 and 2;

or Estrumate (500 mg of clo- prostenol sodium/dose) was from Schering-Plough Animal Health, Union, NL, USAdexperiment 3. The GnRH (100 mg/ dose;

Cystorelin) was from Merial (Duluth, GA, USA). FSH (NIH-FSH-P;

Folltropin-V) was from Bioniche Life Sciences (Belleville, ON, Canada). Intravaginal progesterone (P4) implants (Eazi-Breed controlled internal drug release [CIDR];

containing 1.38 g of progesterone) were from P?zer Animal Health. Lidocaine (Lidocaine Hydrochloride Inject- able 2%;