Evaluation of GnRH- versus estradiol-based protocols for ovulation synchronization in postpartum Bos taurus grazing beef cows submitted to fixed-time artificial insemination.

This study compared the effect of a 7-day estradiol- and a 7-day GnRH-based FTAI protocol versus a presynchronized GnRH-based FTAI protocol (7 & 7 GnRH) on pregnancy per AI (P/AI) in multiparous postpartum Angus cows. Cows were blocked according to presence/absence of a CL, body condition score, and days postpartum and assigned randomly to one of three treatments: I) 7-day EB (n = 368), estradiol benzoate (EB) and intravaginal progesterone-(P4)-releasing device (IVPD) on Day -10, prostaglandin F (PG), equine chorionic gonadotropin (eCG) and estradiol cypionate (ECP) at IVPD removal on Day -3 with FTAI done on Day -1 (54 ± 2 h after IVPD removal); II) 7-day GnRH (n = 367), GnRH at IVPD insertion on Day -10, PG and eCG at IVPD removal on Day -3 with GnRH and FTAI on Day 0 (66 ± 2 h after IVPD removal); and III) 7 & 7 GnRH (n = 361), PG at IVPD insertion on Day -17, GnRH on Day -10, IVPD removal, PG and eCG on Day -3 with GnRH and FTAI on Day 0 (66 ± 2 h after IVPD removal). Preovulatory follicle diameter, corpus luteum (CL) presence, CL area, and P4 concentration were determined at IVPD removal, as well as estrus expression at FTAI and P/AI between 35 and 40 days after FTAI.

Comparison of Gonadotropin-Releasing Hormone versus Estrogen-Based Fixed-Time Artificial Insemination Protocols in Grazing Suckled Beef Cows.

Fixed-timed artificial insemination (FTAI) protocols for beef cattle in South America are primarily based on estradiol esters and intravaginal progesterone-releasing devices (IVPD). The objective of this study was to determine the optimal gonadotropin-releasing hormone (GnRH)-based protocol as an alternative to the use of estrogen-based protocols in grazing suckling beef cows. All cows received an IVPD on the day of protocol initiation and prostaglandin F (PG) plus equine chorionic gonadotropin (eCG) treatments at the time of IVPD removal.

Development of a blood calcium test for hypocalcemia diagnosis in dairy cows.

Hypocalcemia, defined as total blood calcium concentrations below 2.1 mM, has detrimental impacts on welfare, production and reproduction in dairy cattle. Yet, no cow-side test exists for testing total bovine blood calcium.

Effect of Exogenous Progesterone or Flunixin Meglumine After AI on Serum Progesterone Concentration and Pregnancy per AI in Lactating Dairy Cows.

The objective of this study was to determine the effect of post AI administration of exogenous progesterone (P) or a prostaglandin F2α (PGF2α) synthesis inhibitor agent on serum P concentrations and pregnancy per AI (P/AI) in lactating dairy cows. Eighty lactating cows were randomly allocated to one of four treatment groups: 1) CON (control), received 5 mL of saline solution on d 6 and 14 post AI; 2) IP4 (injection of P ), received 125 mg of P im on d 6 and 14 post AI; 3) CIDR, received a controlled internal drug release insert containing 1.38g of P from d 6 to 20 post AI; and 4) FM (Flunixin Meglumine), received 0.

Poly(N-isopropylacrylamide) microgel-based etalons for the label-free quantitation of estradiol-17β in aqueous solutions and milk samples.

A novel estradiol-17β (E2) biosensor was constructed from poly(N-isopropylacrylamide) (pNIPAm) microgel-based etalons by modification of their outermost Au layer with an E2 binding 75-mer DNA aptamer. When E2 is not present in the solution, the aptamer forms a loose/linear structure that allows ions to pass through and into the microgel layer. The ions can change the solvation state of the microgels, which changes the optical properties of the etalon.

Update on Multiple Ovulations in Dairy Cattle.

This review updates the causal mechanisms and risk factors for multiple ovulations (MOV) in cattle. Clearly, MOV can lead to twin pregnancies, which negatively affects the health, production, and reproduction of cows. Therefore, a better understanding of the factors causing MOV may help to reduce twinning.

Dynamics of pre- and post-insemination progesterone profiles and insemination outcomes determined by an in-line milk analysis system in primiparous and multiparous Canadian Holstein cows.

The objective was to evaluate in-line milk progesterone (mP4) data to determine dynamics of pre- and post-insemination mP4 profiles and their associations with parity and outcomes of artificial insemination (AI) in Holstein cows. Milk progesterone (ng/mL) was quantified at pre-determined time points before and after AI through an automated in-line milk analysis system (Herd Navigator™, DeLaval International, Tumba, Sweden). Only AI (∼d0; n = 605) preceded by an mP4-decline (at least two samples of mP4 ≥5 ng/mL followed by at least one sample <5 ng/mL; d-2) were evaluated.

Relationships among early postpartum luteal activity, parity, and insemination outcomes based on in-line milk progesterone profiles in Canadian Holstein cows.

The objectives of this retrospective study were to use in-line milk progesterone (mP4) data to investigate relationships of (1) commencement of luteal activity (CLA), and (2) luteal phase (LP) length and frequency preceding first postpartum AI, with parity and AI outcomes in Canadian Holstein cows. Starting 21 ± 1 days postpartum (DPP), levels of mP4 were assessed every 2.2 ± 2.

Pregnancy per AI in Holstein heifers inseminated with sex-selected or conventional semen after estrus detection or timed-AI.

This study compared pregnancy per AI (P/AI) of heifers inseminated with sex-selected or conventional semen after estrus detection (ED) or timed-AI (TAI). Heifers in the ED group received 2 treatments with prostaglandin F2α 14 d apart and those in the TAI group received a modified 5-day Co-synch protocol plus an intravaginal progesterone releasing insert device (PRID) and were inseminated 72 h after PRID removal. Overall P/AI were 69.

Transcriptome Profiling of In-Vivo Produced Bovine Pre-implantation Embryos Using Two-color Microarray Platform.

Early embryonic loss is a large contributor to infertility in cattle. Moreover, bovine becomes an interesting model to study human preimplantation embryo development due to their similar developmental process. Although genetic factors are known to affect early embryonic development, the discovery of such factors has been a serious challenge.

Morphologic and transcriptomic assessment of bovine embryos exposed to dietary long-chain fatty acids.

The main objectives of this study were to determine the influence of diets enriched in α-linolenic, linoleic or oleic acid on the development and transcriptomic profile of embryos collected from dairy cattle. Non-lactating Holstein cows received one of the three diets supplemented with 8% rolled oilseeds: flax (FLX, n = 8), sunflower (SUN, n = 7) or canola (CAN, n = 8). After a minimum 35-day diet adaptation, cows were superovulated, artificially inseminated and ova/embryos recovered non-surgically after 7.

Alterations in bone morphogenetic protein 15, growth differentiation factor 9, and gene expression in granulosa cells in preovulatory follicles of dairy cows given porcine LH.

In a previous work, using porcine LH (pLH) in lieu of GnRH for synchronizing ovulation in dairy cows improved pregnancy rates without increasing plasma progesterone concentrations after ovulation. The LH profile is known to remain elevated above basal concentrations (≥1 ng/mL) for up to 20 hours in pLH-treated cows compared to less than 6 hours in GnRH-treated cows. Because LH triggers a cascade of signaling networks in the preovulatory follicle to promote final maturation and support oocyte competence, we hypothesized that dissimilar LH profiles will differentially regulate the intrafollicular factors and expression of downstream genes associated with improved oocyte competence.

Effects of prepartum oilseed supplements on subclinical endometritis, pro- and anti-inflammatory cytokine transcripts in endometrial cells and postpartum ovarian function in dairy cows.

Postpartum uterine infections affect ovarian function and delay ovulation in cattle. As dietary fats can affect immune cell function, we investigated the influence of prepartum diets on postpartum uterine inflammatory status (UIS) as assessed 25±1 days postpartum by endometrial cytology (normal: ≤8% polymorphonuclear cells (PMN) vs subclinical endometritis (SCE): >8% PMN) and associations between SCE, pro- and anti-inflammatory cytokine gene expression and ovarian function. During the last 5 weeks of gestation, dairy cows received a diet supplemented with 8% rolled sunflower (n=10) or canola seed (n=9) or no oilseed (n=9).

A prepartum diet supplemented with oilseeds high in oleic or linoleic acid reduced GnRH-induced LH release in dairy cows during second week postpartum.

Background: The objective was to determine the effect of prepartum diets supplemented with rolled canola seed (high in oleic acid) or sunflower seed (high in linoleic acid) on luteinizing hormone (LH) pulsatility and gonadotropin releasing hormone (GnRH)-induced LH release during early postpartum.

Methods: Thirty-one pregnant Holstein cows, blocked by body condition score, parity and expected calving date, were assigned to 1 of 3 prepartum diets supplemented with 8 % rolled canola or sunflower seed, or no oilseed (control) during the last 35 d of gestation. Blood samples were collected at Weeks (wk)-3, 0, +1 and +2, relative to calving, to determine non-esterified fatty acids (NEFA), Beta-hydroxy butyric acid (BHBA) and glucose.

A review of current timed-AI (TAI) programs for beef and dairy cattle.

This is a review of the physiology and endocrinology of the estrous cycle and how ovarian physiology can be manipulated and controlled for timed artificial insemination (TAI) in beef and dairy cattle. Estrus detection is required for artificial insemination (AI), but it is done poorly in dairy cattle and it is difficult in beef cattle. Protocols that synchronize follicle growth, corpus luteum regression and ovulation, allowing for TAI, result in improved reproductive performance, because all animals are inseminated whether they show estrus or not.

Progesterone supplementation before timed AI increased ovulation synchrony and pregnancy per AI, and supplementation after timed AI reduced pregnancy losses in lactating dairy cows.

One of the causes of poor fertility in high producing dairy cows is inadequate progesterone. Therefore, we determined the efficacy of an intravaginal insert containing 1.55 g of progesterone (PRID) given before and/or after timed AI (TAI) on ovarian response, plasma progesterone concentrations, pregnancy per AI (P/AI) and pregnancy losses.

Relationships between endometrial cytology and interval to first ovulation, and pregnancy in postpartum dairy cows in a single herd.

The objectives were to investigate the relationships between endometrial cytology (EC) and interval from calving to first ovulation, and pregnancy in dairy cows, and that between uterine fluid and EC. On day 25 postpartum, 39 dairy cows were grouped based on EC, as having low (≤8%) or high (>8%) polymorphonuclear cells (PMN), and the quantity of uterine fluid was assessed by ultrasound. The interval from calving to first ovulation was shorter in low, than in high PMN cows (32 vs.

Fecal and urinary lignans, intrafollicular estradiol, and endometrial receptors in lactating dairy cows fed diets supplemented with hydrogenated animal fat, flaxseed or sunflower seed.

We hypothesized that the inclusion of flaxseed in the diets of lactating dairy cows will increase urinary and fecal concentrations of the lignans, secoisolariciresinol diglycoside (SDG), enterolactone and enterodiol, reduce intrafollicular concentrations of IGF-I and estradiol, and subsequently reduce estradiol and oxytocin receptor expression in the endometrium. To test this hypothesis, 27 cycling, lactating Holstein cows were assigned to 1 of 3 diets supplemented with saturated fatty acids (SAT), flax (FLX), or sunflower (SUN) seed. Rations were formulated to provide 750 g supplemental fat/cow/d in all dietary groups.

Comparison of 2 enzyme immunoassays and a radioimmunoassay for measurement of progesterone concentrations in bovine plasma, skim milk, and whole milk.

The objective of this study was to compare 2 enzyme immunoassays (EIAs) with a radioimmunoassay (RIA) as to sensitivity and accuracy in the measurement of the progesterone (P4) concentration in bovine plasma, skim milk, and whole milk. The 72 samples from 24 lactating dairy cows expected to have either a high P4 concentration (cows in diestrus or pregnant) or a low P4 concentration (cows in estrus or anestrus) were analyzed by RIA, solid-phase EIA (SPEIA), which included a solvent extraction step, or direct EIA (DEIA) without solvent extraction. The overall mean concentrations of P4 did not differ (P < 0.

Resynchronization of estrus in beef cattle: ovarian function, estrus and fertility following progestin treatment and treatments to synchronize ovarian follicular development and estrus.

The objective was to optimize rebreeding of nonpregnant, previously inseminated beef cattle. In Experiment 1, 43 cows received a used intravaginal progesterone-releasing insert (IVPRI; Days 0-7) 12.3 d after ovulation and received concurrently no treatment, 100 microg gonadotropin releasing hormone (GnRH), 1 mg estradiol cypionate (ECP), or 150 mg progesterone.

Effects of plasma progesterone concentrations on LH release and ovulation in beef cattle given GnRH.

The effects of plasma progesterone concentrations on LH release and ovulation in beef cattle given 100 microg of GnRH im were determined in three experiments. In Experiment 1, heifers were given GnRH 3, 6 or 9 days after ovulation; 8/9, 5/9 and 2/9 ovulated (P<0.02).

Effects of estradiol cypionate (ECP) on ovarian follicular dynamics, synchrony of ovulation, and fertility in CIDR-based, fixed-time AI programs in beef heifers.

Estradiol cypionate (ECP) was used in beef heifers receiving a controlled internal drug release (CIDR; insertion = Day 0) device for fixed-time AI (FTAI) in four experiments. In Experiment 1, heifers (n = 24) received 1mg ECP or 1mg ECP plus 50mg commercial progesterone (CP) preparation i.m.

The ischiorectal fossa: an alternative route for the administration of prostaglandin in cattle.

Three experiments were conducted to investigate the ischiorectal fossa (IRF) as a route for the administration of prostaglandin F2 alpha (dinoprost) in cattle. In Experiment 1, 21 nonlactating Holstein cows were given 100 micrograms of gonadotropin releasing hormone (GnRH), intramuscularly (i.m.