Effects of polyunsaturated fatty acid supplementation on plasma and follicular fluid resolvin D1 concentration and mRNA abundance in granulosa cells in ewes.

The aim of this experiment was to evaluate the effect of increasing dietary omega-3 (n-3) polyunsaturated fatty acid (PUFA) supplementation on plasma and follicular fluid resolvin D1 (RvD1) concentration and the mRNA expression of genes related to RvD1 production, inflammatory response, oxidative stress, hormone receptors and production, and free fatty acid receptors in the granulosa cells of ewes. Dorset × Hampshire ewes (n = 24) aged 2 to 4 yr and with an initial body weight (BW) of 84.08 ± 13.

Effect of use and dosage of p-follicle-stimulating hormone for ovarian superstimulation before ovum pick-up and in vitro embryo production in pregnant Holstein heifers.

The benefit of ovarian superstimulation using exogenous FSH before ovum pick-up (OPU) and in vitro embryo production (IVEP) has been the subject of conflicting results. The objective of the present study, therefore, was to evaluate the effect of use and dose of porcine FSH (p-FSH) before OPU/IVEP on ovarian response and embryo production in pregnant heifers. Pregnant Holstein heifers (n = 48) were randomly assigned to receive 0, 160, or 300 mg NIH-FSH-P1 in a crossover design.

Research on timed AI in beef cattle: Past, present and future, a 27-year perspective.

This review aimed to (1) summarize the results from fixed-timed artificial insemination (TAI) fertility studies performed during the last 27 years; (2) compile and evaluate, as examples from the literature base, the direct comparisons made of specific manipulations to synchronization protocols; (3) evaluate the impact of the TAI programs on the reproductive performance during the breeding season, and (4) provide perspective on the future of TAI programs in beef cattle. A search of the literature published from 1995 to 2021 was conducted to identify experiments in which synchronization of ovulation and TAI in beef cattle was performed. The primary outcome of interest was fertility expressed as pregnancies per TAI.

Preantral follicle numbers and size in heifers carrying Trio, a bovine high fecundity allele.

In Brief: The bovine high fecundity allele, Trio, results in the occurrence of multiple ovulations and is characterized by antral follicles that develop slower and acquire ovulatory capacity at smaller sizes. This study provides novel information on the effect of the Trio allele on early folliculogenesis.

Abstract: The bovine high fecundity allele, Trio, causes overexpression in granulosa cells (GCs) of SMAD6, an inhibitor of BMP15-activated SMAD signalling.

Environmental stress during the last trimester of gestation in pregnant cows and its effect on offspring growth performance and response to glucose and adrenocorticotropic hormone.

Winter and spring precipitation are predicted to increase in the Midwest region of the United States, causing muddy conditions. In a previous experiment, Angus cows (8 per treatment) were paired based on initial body weight (BW) and one cow from each pair was randomly allocated to either the mud or control treatment. Though cows consumed the same amount of dry matter, cows in the mud treatment weighed 37.

Energy restriction and housing of pregnant beef heifers in mud decreases body weight and conceptus free live weight.

Average temperatures in the Midwest, USA are predicted to increase 2-9°C by the end of the century; resulting in muddy pastures for spring calving beef heifers as they enter late gestation. The objective of this study was to evaluate the effects of muddy conditions on heifer body weight (BW), body condition score (BCS), conceptus free live weight (CFLW), and fetal growth when heifers were energy restricted during late gestation. Eighteen Angus heifers ( = 9/treatment) were paired based on initial BW.

Short communication: A comparison between two glucose measurement methods in beef steers during a glucose tolerance test.

Glucose tolerance tests (GTT) are commonly performed in beef cattle to evaluate the glucose-insulin signaling pathway. Blood samples are obtained via a catheter and then transferred back to the laboratory for further analysis. A hand-held glucometer used chute-side can make performing GTT's and quantifying blood glucose concentration much easier and faster for research purposes.

Synchronization of follicle wave emergence before ovarian superstimulation with FSH and ovum pick-up improves in vitro embryo production in pregnant heifers.

The objective of the present study was to evaluate effects of synchronization of timing of follicle wave emergence, before ovarian superstimulation and ovum pick-up (OPU), on ovarian response and embryo production in pregnant heifers. Pregnant (47-69 days of gestation) Holstein heifers (n = 64), 19.0 ± 0.

Beef cows housed in mud during late gestation have greater net energy requirements compared with cows housed on wood chip bedding.

Mud increases net energy requirements for cattle because mud and precipitation compromise the ability of the hair coat to insulate and maintain core body temperature of the cow. The increase in energy required for a gestating cow to compensate for a muddy environment is unknown. The objective of this study was to evaluate effects of muddy conditions on cow body weight (BW) and fetal growth during late gestation.

Selection of fewer dominant follicles in Trio carriers given GnRH antagonist and luteinizing hormone action replaced by nonpulsatile human chorionic gonadotropin†.

Studying selection of multiple dominant follicles (DFs) in monovulatory species can advance our understanding of mechanisms regulating selection of single or multiple DFs. Carriers of the bovine high fecundity Trio allele select multiple DFs, whereas half-sib noncarriers select a single DF. This study compared follicle selection during endogenous gonadotropin pulses versus during ablation of pulses with Acyline (GnRH antagonist) and luteinizing hormone (LH) action replaced with nonpulsatile human chorionic gonadotropin (hCG) treatment in Trio carriers (n = 28) versus noncarriers (n = 32).

Postovulatory treatment with GnRH on day 5 reduces pregnancy loss in recipients receiving an in vitro produced expanded blastocyst.

The present study tested the hypothesis that administration of GnRH on day 5 of the estrous cycle in embryo transfer (ET) recipients would increase progesterone (P4) concentrations, embryo size, and improve fertility. Holstein and cross-bred Holstein heifers (n = 1562) were synchronized using a modified 5-day CIDR-Synch protocol as follows (All AM treatments): D-8, CIDR inserted; D-3, CIDR removed and PGF2α (500 μg cloprostenol) treatment; D-2, second PGF2α; D0, GnRH (G1, 100 μg gonadorelin acetate) to induce ovulation. On D5 in the afternoon, heifers were assigned in a completely randomized design to one of two treatments: Control (untreated) or GnRH (200 μg).

Mechanisms regulating follicle selection in ruminants: lessons learned from multiple ovulation models.

Selection of a single dominant follicle from a cohort of growing follicles is a unique biological process, a key step in female reproductive function in monovular species, and lies at the core of reproductive technologies in cattle. Follicle growth and the number of follicles that ovulate are regulated by precise endocrine, paracrine, and autocrine mechanisms. Most of our current understanding about follicle selection focuses on the role of FSH, LH, and the IGF family in follicle growth and selection of the dominant follicle.

Physiological mechanisms involved in maintaining the corpus luteum during the first two months of pregnancy.

Maintenance of the corpus luteum (CL) during pregnancy is essential for continuing the elevated circulating progesterone (P4) that is required to maintain pregnancy. The mechanisms that protect the CL during early pregnancy when the non-pregnant animal would typically undergo CL regression have been extensively investigated. It is clear uterine prostaglandin F2α (PGF) causes regression of the CL in non-pregnant ruminants and that maintenance of the CL during early pregnancy is dependent upon secretion of interferon-tau (IFNT) from the elongating embryo.

Proteomic analysis of follicular fluid in carriers and non-carriers of the Trio allele for high ovulation rate in cattle.

This study was conducted to characterise differences in follicular fluid proteins between carriers and non-carriers of a bovine allele for high ovulation rate. A total of four non-carrier and five carrier females were used in an initial study with four and six additional non-carriers and carriers respectively used in a validation study. Emergence of the follicular wave was synchronised and the ovaries containing the dominant follicle(s) were extracted by ovariectomy for follicular fluid collection.

Trio, a novel bovine high fecundity allele: III. Acquisition of dominance and ovulatory capacity at a smaller follicle size.

The acquisition of dominance and ovulatory capacity was evaluated in follicles from cows that were carriers or half-sibling noncarriers of the Trio allele. Follicle size at acquisition of follicular dominance was determined by evaluating whether follicles ovulate after GnRH challenge (ovulatory capacity-experiment 1) and by determination of intrafollicular concentrations of estradiol and free insulin like growth factor 1 (IGF1) and relative mRNA expression of cytochrome P450 family 19 subfamily A member 1 (CYP19A1), luteinizing hormone/choriogonadotropin receptor (LHCGR), and pappalysin 1 (PAPPA, previously known as pregnancy-associated plasma protein A, pappalysin 1) in granulosa cells from follicles of different sizes (experiment 2). Ovulatory capacity developed in follicles at 8.

Trio a novel bovine high-fecundity allele: II. Hormonal profile and follicular dynamics underlying the high ovulation rate.

The newly discovered Trio high-fecundity allele produces multiple ovulations in cattle. This study evaluated (1) size and growth rates of follicles in Trio carriers during a synchronized follicular wave, induced by follicle aspiration; (2) follicle-stimulating hormone (FSH) patterns associated with the follicular wave; (3) size of corpora lutea (CL) and circulating progesterone; and (4) intrafollicular estradiol concentrations prior to normal deviation. Trio carriers had mean dominant follicles that were significantly smaller in diameter and volume than noncarriers.

Mechanisms for rescue of corpus luteum during pregnancy: gene expression in bovine corpus luteum following intrauterine pulses of prostaglandins E1 and F2α.

In ruminants, uterine pulses of prostaglandin (PG) F2α characterize luteolysis, while increased PGE2/PGE1 distinguish early pregnancy. This study evaluated intrauterine (IU) infusions of PGF2α and PGE1 pulses on corpus luteum (CL) function and gene expression. Cows on day 10 of estrous cycle received 4 IU infusions (every 6 h; n = 5/treatment) of saline, PGE1 (2 mg PGE1), PGF2α (0.

Effect of feeding rumen-protected methionine on productive and reproductive performance of dairy cows.

The objectives of this study were to evaluate the effects of daily top-dressing (individually feeding on the top of the total mixed ration) with rumen-protected methionine (RPM) from 30 ± 3 until 126 ± 3 Days in milk on productive and reproductive performance in lactating dairy cows. A total of 309 lactating dairy Holstein cows (138 primiparous and 171 multiparous) were randomly assigned to treatment diets containing either RPM (21.2 g of RPM + 38.

Trio, a novel high fecundity allele: I. Transcriptome analysis of granulosa cells from carriers and noncarriers of a major gene for bovine ovulation rate.

A major gene for bovine ovulation rate has been mapped to a 1.2 Mb region of chromosome 10. Screening of coding regions of positional candidate genes within this region failed to reveal a causative polymorphism, leading to the hypothesis that the phenotype results from differences in candidate gene expression rather than alteration of gene structure.

Follicular waves and hormonal profiles during the estrous cycle of carriers and non-carriers of the Trio allele, a major bovine gene for high ovulation and fecundity.

A high fecundity bovine genotype has recently been discovered and genetic mapping indicates evidence for segregation of a major gene with influence on ovulation rate located on bovine chromosome 10. Cattle carrying the high fecundity allele, referred to as the Trio allele, have multiple ovulations while half-sibling, non-carriers generally have single ovulations. The present study was designed to evaluate follicle wave patterns and associated circulating hormones during the estrous cycle of Trio allele carriers (n = 7) and non-carrier half-sib controls (n = 5).

Ovulation rate, antral follicle count, and circulating anti-Müllerian hormone in Trio allele carriers, a novel high fecundity bovine genotype.

High fecundity genotypes in sheep are a valuable model to study the physiological mechanisms underlying follicle selection and the control of ovulation rate. Similar genotypes in cattle had not been described until the recent identification of a major bovine allele, termed Trio, which had a large effect on ovulation rate. The present study was designed to evaluate ovulation rate, antral follicle count (AFC), circulating ant-müllerian hormone (AMH), and the association among these measures in unstimulated and superstimulated Trio carrier cattle.

Pivotal periods for pregnancy loss during the first trimester of gestation in lactating dairy cows.

Loss of pregnancy can occur at many different stages of gestation and for a variety of causes but clearly produces a negative impact for reproductive and economic performances of dairy herds. This review describes four pivotal periods for pregnancy loss during the first trimester of gestation and discusses possible causes for pregnancy failure during these periods. The first period occurs during the first week after breeding with lack of fertilization and death of the early embryo producing major losses in pregnancy, particularly under specific environmental and hormonal conditions.

Effect of sample pooling and transport conditions on the clinical sensitivity of a real-time polymerase chain reaction assay for Campylobacter fetus subsp. venerealis in preputial samples from bulls.

The diagnosis of bovine genital campylobacteriosis (BGC) presents significant challenges, as traditional methods lack sensitivity when prolonged transport of samples is required. Assays of preputial samples by means of real-time polymerase chain reaction (PCR) provide good sensitivity and high throughput capabilities. However, there is limited information on the acceptable duration of transport and temperature during transport of samples.

Clinical sensitivity and specificity of a real-time PCR assay for Campylobacter fetus subsp venerealis in preputial samples from bulls.

Objective: To determine clinical sensitivity and specificity of a quantitative real-time PCR (qRT-PCR) assay for Campylobacter fetus subsp venerealis (Cfv) in preputial samples of bulls.

Animals: 313 beef bulls.

Procedures: Preputial samples were collected from 300 virgin bulls and 13 Cfv-infected bulls.

Use of pooled protozoal cultures of preputial scraping samples obtained from bulls for the detection of Tritrichomonas foetus by means of a real-time polymerase chain reaction assay.

Objective: To determine the sensitivity of a real-time PCR assay for the detection of Tritrichomonas foetus in protozoal cultures of preputial scraping samples pooled from up to 25 bulls and to determine the specificity of that assay for detection of T foetus in cultures for individual animals.

Design: Cross-sectional study.

Animals: 188 bulls and 150 steers.