Effect of oestrous expression prior to timed artificial insemination with sexed semen on pregnancy rate in dairy cows.

The objectives of the study were to determine (1) oestrous expression rate and (2) the effect of oestrous expression prior to progesterone-based Ovsynch protocol on pregnancy rate in Holstein cows. All cows (n = 917) were subjected to 7-day progesterone-based Ovsynch protocol. In this protocol, cows that expressed oestrus before (HEAT1) the scheduled second GnRH were inseminated 20 h later after the onset of oestrus without GnRH administration.

Effect of delaying the time of insemination with sex-sorted semen on pregnancy rate in Holstein heifers.

The objective of the study was to evaluate the interval from onset of oestrus to time of artificial insemination (AI) to obtain the optimum pregnancy rate with sex-sorted semen in Holstein heifers. Heifers in oestrus were detected and inseminated only by using heat-rumination neck collar comprised electronic identification tag at the age of 13-14 months. Heifers (n = 283) were randomly assigned to one of three groups according to the timing of insemination at 12-16 hr (G1, n = 97), at 16.

Fertility of lactating dairy cows inseminated with sex-sorted or conventional semen after Ovsynch, Presynch-Ovsynch and Double-Ovsynch protocols.

The objective was to compare pregnancy per artificial insemination (P/AI) with conventional (CS) or sex-sorted semen (SS) in dairy cows subjected to one of the three timed AI protocols. Cows (n = 356) were randomly assigned to synchronization with Ovsynch (OVS), Presynch-Ovsynch (PO) or Double-Ovsynch (DO) and inseminated on Day 77 ± 3 postpartum with either frozen-thawed SS (n = 182) or CS (n = 184) of the same bull. More cows were cyclic at the beginning of breeding Ovsynch increased (p < 0.

Fertility in dairy cows after artificial insemination using sex-sorted sperm or conventional semen.

The aim of this study was to compare pregnancy per artificial insemination (P/AI) after timed AI with sex-sorted sperm (SS) or conventional semen (CS) in lactating dairy cows. Cyclic cows (n = 302) were synchronized by Ovsynch and randomly assigned into two groups at the time of AI. Cows with a follicle size between 12 and 18 mm and clear vaginal discharge at the time of AI were inseminated with either frozen-thawed SS (n = 148) or CS (n = 154) of the same bull.

Comparison of synchronisation and fertility after different modifications of the ovsynch protocol in cyclic dairy cows.

The objectives of this study were to evaluate the effects of (1) double doses of PGF2α administration or (2) an exogenous progesterone (CIDR) applied concurrently with, or (3) the day after, first GnRH of Ovsynch (GnRH-1), on synchronisation and fertility during the Ovsynch protocol. All cows (n = 378) received the Ovsynch protocol (GnRH-7d-PGF2α-56h-GnRH-18h-TAI). The 'OVS' group (n = 105) received only the Ovsynch protocol.

Perosomus elumbis in a Holstein calf infected with bovine viral diarrhea virus.

The detection of bovine viral diarrhea virus (BVDV) in a female Holstein calf presented with perosomus elumbis, a congenital anomaly, is reported here. A cow with dystocia was evaluated and an abnormal dead calf was detected during vaginal examination. The calf was retrieved via caesarean section and exhibited abnormalities characteristic of PE, such as vertebral and pelvic malformations.

Relation between intravascular electrolyte level and course of parturition in dairy cows.

Objective: To determine the intravascular electrolyte status in dairy cows with respect to age and different courses of parturition to clarify etiological factors influencing peri- or intrapartal imbalances of electrolyte homeostasis.

Material And Methods: A total of 64 cows at birth were evaluated (primiparous n = 34, pluriparous n = 30). Thirty-three cows showed normal delivery, while 31 cows had a complicated birth.

Reducing the duration between gonadotropin-releasing hormone (GnRH) and prostaglandin F₂α treatment in the Ovsynch protocol to 6 days improved ovulation to second GnRH treatment, but inclined to reduce fertility.

The aim of this study was to test Ovsynch (OVS) versus modified OVS (decreasing the interval between first GnRH and PGF2α to 6d) protocols on pregnancy per artificial insemination (AI) and OVS outcomes in cyclic dairy cows. Cyclic cows (n=920) were assigned to 1 of 2 groups: the OVS7 group (n=459) received the OVS protocol [GnRH treatment, PGF2α treatment 7d later, a second GnRH (GnRH2) treatment 56 h later, and timed AI (TAI) 16 to 18 h after the GnRH2 treatment], and the OVS6 group (n=461) received a modified OVS protocol, in which the interval between the first GnRH and PGF2α was decreased to 6d (GnRH treatment, PGF2α treatment 6d later, GnRH2 treatment 56 h later, and TAI 16 to 18h after the GnRH2 treatment). The response to the first GnRH of OVS was similar between OVS7 (54.

Effects of presynchronization with gonadotropin-releasing hormone-prostaglandin F2α or progesterone before Ovsynch in noncyclic dairy cows.

The aim of this study was to evaluate the efficiency of presynchronization with GnRH and PGF(2α) or with progesterone on overall Ovsynch (OVS) outcomes in noncyclic dairy cows. Cows were scanned 7 d apart with ultrasonography to determine cyclicity. Noncyclic cows (n=281; no corpus luteum on ovaries at both examinations) were randomly divided into 3 groups.

Effect of presynchronization strategy before Ovsynch on fertility at first service in lactating dairy cows.

The aim of this study was to evaluate the effect of presynchronization with or without the detection of estrus on first service pregnancy per artificial insemination (P/AI) and on Ovsynch outcome in lactating dairy cows. A total of 511 cows were divided randomly but unevenly into 3 treatment groups at 44 to 50 days in milk (DIM). Ovsynch was started at the same time (69 to 75 DIM) in all three groups.

Dry period management and optimization of post-partum reproductive management in dairy cattle.

Dry period and early post-partum management are decisive factors for fertility in lactating dairy cows. Previous studies have shown that decreased dry matter intake (DMI) and increased non-esterified fatty acids (NEFA) negatively affect fertility and subsequent milk production. The traditional dry period decreases DMI prior to parturition, resulting in a decrease in energy intake.

Comparison of responses to Ovsynch between Holstein-Friesian and Swedish Red cows.

The Ovsynch protocol was designed to synchronize ovulation, thereby allowing timed artificial insemination (TAI) of all cows without detection of estrus. However, the effectiveness of Ovsynch in different breeds of dairy cows has not been previously compared. The aim of this study was to compare the response to Ovsynch in cycling lactating Holstein-Friesian (HF) and Swedish Red (SR) dairy cows.

Effect of hCG vs. GnRH at the beginning of the Ovsynch on first ovulation and conception rates in cyclic lactating dairy cows.

Ovulatory response to the first GnRH of Ovsynch is a very important factor for determining the outcome of a successful synchronization. The aim of the present study was to develop a protocol to increase the percentage of cows that ovulated in response to the first administration of Ovsynch. This study was designed to compare ovulation rates in response to GnRH or hCG at the beginning of Ovsynch and to evaluate the effects of this manipulation on pregnancy.