The variation in the beta-casein genotypes and its effect on milk yield and genomic values in Holstein-Friesian cows.

The A2 milk marker is gaining popularity worldwide; thus, many farms plan to convert their dairy cattle herds to the A2A2 genotype. Variation in beta-casein genotypes needs to be monitored in large dairy cattle populations. Therefore we aimed to evaluate the genotypic distributions, population genetics, and diversity parameters in Holstein-Friesian cows.

Effects of daily propylene glycol drenching during the Ovsynch protocol on fertility and metabolic parameters in lactating dairy cows.

Negative energy balance (NEB) caused by restricted feed intake leads to body condition loss (BCS), increased metabolic stress and reduced fertility in dairy cows. Propylene glycol (PG) is a precursor of ruminal propionate for gluconeogenesis used to increase metabolic adaptation to the early postpartum period. The aim of this study was to determine the effects of daily drenching of PG during the fixed-time artificial insemination (FTAI) protocol on beta-hydroxybutyric acid (BHBA), glucose, adiponectin, insulin-like growth factor-1 (IGF1) concentrations, follicle size and pregnancy rate in dairy cows.

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.

Comparison of pregnancy per AI of heifers inseminated with sex-sorted or conventional semen after oestrus detection or timed artificial insemination.

The objective of the study was to compare the fertility after using sex-sorted or conventional semen either with oestrus detection (EST) or timed artificial insemination (TAI) in Holstein heifers. Holstein heifers were randomly assigned to one of the following treatments in a 2 × 2 factorial design. Heifers in the EST group were inseminated with sex-sorted (n = 114) or conventional semen (n = 100) after spontaneous or induced oestrus.

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.

Association among lipopolysaccharide, the transforming growth factor-beta superfamily, follicular growth, and transcription factors in spontaneous bovine ovarian cysts.

The aim of this study was to investigate some of the growth and transcriptional factors originating from oocytes and granulosa cells in follicular fluid and to identify the relationships between the basic blood metabolite-metabolic hormones and intrafollicular lipopolysaccharide (LPS) concentrations. Thirty cows included in the study were allocated into 2 groups comprising 15 cows with healthy preovulatory follicles (cyclic cows) and 15 cows with confirmed cystic follicles. The ovaries and uteri of all cows were assessed by transrectal ultrasonographic examination.

Effect of presynchronization with prostaglandin F before the 5-d timed AI protocol on ovarian responses and pregnancy in dairy heifers.

The objectives were the determine the effects of presynchronization with PGF 2 days before the 5-d timed artificial insemination (AI) protocol on ovarian responses and pregnancy per AI (P/AI) in dairy heifers. The hypothesis was that PGF would induce responsive heifers to be in proestrus at the initiation of the timed AI protocol, which was expected to improve ovulatory responses and P/AI. Weekly cohorts of Holstein heifers were blocked by age and, within block, randomly assigned to remain as control (CON; n = 255) or receive PGF on experiment Day -10 (PG; n = 255).

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.

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.

Managing the dominant follicle in lactating dairy cows.

Reproductive efficiency is not optimal in high-producing dairy cows. Although many aspects of ovarian follicular growth in cows are similar to those observed in heifers, there are numerous specific differences in follicular development that may be linked with changes in reproductive physiology in high-producing lactating dairy cows. These include: 1) reduced circulating estradiol (E2) concentrations near estrus, 2) ovulation of follicles that are larger than the optimal size, 3) increased double ovulation and twinning, and 4) increased incidence of anovulation with a distinctive pattern of follicle growth in anovular dairy cows.

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.

Ultrasonographic evaluation of endometrial thickness near timed AI as a predictor of fertility in high-producing dairy cows.

The objectives were to evaluate changes in endometrial thickness (ET) near the time of a synchronized ovulation and to assess the relationship of ET and fertility in lactating Holstein cows, with or without estrogen supplementation near timed ovulation. In Experiment 1, eight cows were examined with transrectal ultrasonography, once daily for 5 d, starting concurrent with PGF(2α) (PGF) treatment during an Ovsynch protocol (GnRH - 7d - PGF - 72h - GnRH). The ET increased rapidly after PGF (from ∼7 to ∼9.

The role of luteinizing hormone in regulating gene expression during selection of a dominant follicle in cattle.

At approximately 8.5 mm in diameter, the future dominant follicle is "selected" for continued growth in cattle. In the present study, cows were treated with a gonadotropin-releasing hormone receptor antagonist, acyline, just before follicle selection (near 7.

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.

Managing the dominant follicle in high-producing dairy cows.

Reduced reproductive efficiency has been reported in high-producing dairy cows. Sources of reproductive inefficiency include decreased expression of estrus, increased diameter of the ovulatory follicle and reduced fertility when cows are inseminated after estrus, increased incidence of double ovulation and twinning, and increased pregnancy loss. To overcome some of these inefficiencies, reproductive management programs have been developed that synchronize ovulation and enable effective timed artificial insemination (AI) of lactating dairy cows.

Comparison of gonadorelin products in lactating dairy cows: efficacy based on induction of ovulation of an accessory follicle and circulating luteinizing hormone profiles.

This study evaluated whether the four gonadorelin products that are commercially available in the United States produce comparable ovulation responses in lactating cows. Dairy cows at 7 d after last gonadotropin-releasing hormone (GnRH) treatment of Ovsynch (Day 7), with a corpus luteum (CL) > or =15 mm and at least one follicle > or =10mm, were evaluated for response to GnRH treatment. Selected cows were randomized to receive (100 microg; im): (1) Cystorelin (n=146); (2) Factrel (n=132); (3) Fertagyl (n=140); or (4) Ovacyst (n=140).

Pathological abnormalities after long-term administration of medroxyprogesterone acetate in a queen.

In this report, multiple abnormalities (bilateral ovarian cysts, cystic endometrial hyperplasia and pyometra (CEH-P), mammary adenoma, fibrosarcoma and cystic-papillary adenocarcinoma) identified in a queen continually administered medroxyprogesterone acetate (MPA) for 9 years are described. An 11-year-old domestic shorthair intact queen was presented for reduced appetite, polyuria, polydipsia, abdominal distension, and mammary mass. Pyometra was diagnosed based upon clinical, ultrasonographic and radiographic examinations.

Supplementation with estradiol-17beta before the last gonadotropin-releasing hormone injection of the Ovsynch protocol in lactating dairy cows.

The aim of this study was to determine whether an increase in circulating estrogen concentrations would increase percentage pregnant per artificial insemination (PP/AI) in a timed AI protocol in high-producing lactating dairy cows. We analyzed only cows having a synchronized ovulation to the last GnRH of the Ovsynch protocol (867/1,084). The control group (n = 420) received Ovsynch (GnRH--7 d--PGF(2alpha)--56 h--GnRH--16 h--timed AI).

Production of lymphocyte-activating factors by mouse macrophages during aging and under the effect of short peptides.

Age-specific characteristics of production of lymphocyte-activating factor by mouse peritoneal macrophages and modulation of this production by short synthetic peptides (Vilon, Epithalon, and Cortagen) were studied. The production of lymphocyte-activating factors by macrophages stimulated with lipopolysaccharides in vitro was lower in old animals. The opposite modulating effects of short peptides on the production of lymphocyte-activating factors by resident and lipopolysaccharide-stimulated macrophages in young and old mice were demonstrated for the first time.