Optimisation of Early Pregnancy Diagnosis and Resynchronisation in Beef Cows.

The objectives of this study were (1) to investigate the effects of the preovulatory follicle (POF) size on the accuracy of Doppler-based early pregnancy detection, and (2) to determine whether the removal of PGF2α (PGF) treatment during the resynchronisation protocol would affect fertility in beef cows. In Experiment 1, Nelore suckling cows (n = 224) were enrolled in an estradiol-progesterone-based timed artificial insemination (TAI) protocol. At TAI, cows were separated based on the range of POF diameters, as follows: ≤11.

Selecting oocyte donors based on anti-Müllerian hormone (AMH) concentrations: A critical analysis of using cutoff values as exclusion criterion for an in vitro embryo production program in Gir cattle.

The aims of this study were to determine anti-müllerian hormone (AMH) cutoff values for selecting Gir (Bos taurus indicus) oocyte donors and estimate the impact of using AMH concentrations as a selection criterion. In Exp. 1, Gir heifers (n=120) were sampled for AMH analysis and submitted to ovum pick-up and in vitro embryo production (OPU-IVEP).

Effect of maternal age on ATP content and distribution of mitochondria in bovine oocytes.

Our objective was to understand how maternal age influences the mitochondrial population and ATP content of in vivo matured bovine oocytes. We hypothesized that in vivo matured oocytes from older cows would have altered mitochondrial number and distribution patterns and lower cytoplasmic ATP content compared to the oocytes obtained from younger cows. Follicles ≥5mm were ablated in old cows (13 to 22 yrs, Old Group, n = 7) and their younger daughters (4 to 10 years old, Young Group; n = 7) to induce the emergence of a new follicular wave.

Does GnRH treatment at TAI regardless of estrus occurrence increase pregnancy rate in crossbred suckled cows?

The impact of GnRH treatment on the day of TAI in beef cows has received limited investigation, especially concerning its association with estrus expression. Consequently, two experiments were conducted to assess the potential of GnRH treatment on the day of TAI to enhance fertility according to the expression or not of estrus in beef cows. Experiment 1 aimed to determine ovulation rate and luteal function, while Experiment 2 aimed to determine the effect of the two GnRH treatment approaches on pregnancy rate.

Exploring uterine inflammation in postpartum primiparous precocious and conventional and multiparous Bos indicus beef cows.

This study aimed to compare the postpartum uterine dynamics of primiparous precocious (PP), primiparous conventional (PC) and multiparous conventional (MC) Bos indicus beef cows. For this purpose, PP (n = 8), PC (n = 18) and MC (n = 12) cows were enrolled in this study. These cows were evaluated at 20 and 10 days prepartum and weekly from parturition to 42 days postpartum (DPP).

GnRH34 with or without estradiol cypionate in timed AI in Bos indicus beef cows.

Two experiments were performed to evaluate the effects of GnRH treatment on the fertility of suckled Nelore beef cows treated with an estradiol/progesterone (E2/P4)-based protocol for timed artificial insemination (TAI). Experiment 1 focused on determining the effects of estradiol cypionate (EC) on ovulation in TAI cows treated with GnRH 34 h after removal of the intravaginal P4 device (IPD). Suckled cows (n = 26) were treated with 2 mg estradiol benzoate (EB) and IPD containing 1 g P4.

Early versus late body condition score loss in dairy cows: Reproductive performance.

This study aimed to compare milk production and reproductive performance in high yield Holstein cows that lose BCS early and late in the postpartum period. Lactating dairy cows (n = 76) were received first timed AI at 60 to 75 DIM using the farm-managed estradiol-progesterone-GnRH-based timed AI protocol. The BCS of all cows was daily evaluated by automated BCS cameras.

Does combining estradiol cypionate and GnRH for ovulation induction in recipient cows increase pregnancy rate after timed embryo transfer?

Estradiol cypionate (EC) or GnRH have been widely used for ovulation induction in timed embryo transfer (TET). EC administration increases the proportion of cows that show estrus, whereas GnRH promotes more synchronized ovulations. The aim of the present study was to evaluate the potential beneficial effects of combining EC and GnRH in TET.

GnRH34: An alternative for increasing pregnancy in timed AI beef cows.

Two experiments evaluated the effects of gonadotropin releasing hormone (GnRH) treatment on fertility of suckled Nelore beef cows treated with an estradiol/progesterone (P4)-based protocol for timed artificial insemination (TAI). Experiment 1 was designed to determine the effect of GnRH administered 34 h after P4 insert removal (GnRH34) on time of ovulation. Suckled cows (n = 34) were treated with 2 mg estradiol benzoate (EB) and an intravaginal insert containing 1.

Effects of Prostaglandins E2 and F2α on the in vitro maturation of bovine oocytes.

We aimed to elucidate the effects of PGE2 and PGF2α on the in vitro maturation (IVM) of bovine oocytes. First, cumulus-oocyte complexes were matured in the media supplemented with or without PGE2, PGF2α, or PGE2 plus PGF2α for the final 24, 12, or 6 h of culture. Then, the cumulus-oocyte complexes were matured in the absence or presence of a PG endoperoxide synthase 2 (PTGS2) enzyme inhibitor (NS398) supplemented with PGE2, PGF2α, or PGE2 plus PGF2α.

Vascular and morphological features of the corpus luteum 12 to 20 days after timed artificial insemination in dairy cattle.

Our objective was to retrospectively compare pregnant versus nonpregnant cattle in terms of vascular and morphometric changes in corpora lutea between d 12 and 20 following timed artificial insemination (TAI). Crossbred (Gir × Holstein) lactating dairy cows (n = 136) and heifers (n = 111) were bred after synchronizing ovulations using an estradiol plus progesterone (P4)-based protocol. Corpus luteum (CL) characteristics (area, echotexture, blood flow) were recorded at 48-h intervals from d 12 to 20 following TAI using an ultrasound equipped with color Doppler.

Effect of sperm kinematics and size of follicle at ovulation on pregnancy rate after timed AI of beef cows.

The objectives of this study were to evaluate whether the diameter of the preovulatory follicle and the post-thaw sperm kinematics are factors that affect successful establishment of a pregnancy after timed AI (TAI) of postpartum beef cows. Nelore cows (n = 346) were subjected to an estradiol-progesterone based TAI protocol. At TAI, cows were categorized according to the diameter of the preovulatory follicle (POF) in the Early Ovulation (EO group, n = 184), and Late Ovulation (LO group, n = 162) groups.

Different protocols using PGFα as ovulation inducer in Nelore cows subjected to estradiol-progesterone timed AI based protocols.

The objective of this study was to evaluate the effect of a PGFα-analogue (PGF) on ovulation and pregnancy rates after timed artificial insemination (TAI) in cattle. In Experiment 1 cows received an intravaginal progesterone-releasing device (CIDR) plus 2 mg im of estradiol benzoate (EB) on Day 0. The CIDR devices were removed on Day 8, and all cows received 150 μg im of d-cloprostenol (PGFα-analogue), 300 IU of eCG and 1 mg of estradiol cypionate (ECP) im.

Effect of serum paraoxonase-1 (PON1) activity on follicular development and pregnancy rate in cattle.

Paraoxonase-1 (PON1) activity has been associated with improvement in ovarian function in early postpartum dairy cows and improved in vitro embryo development. The aim of the current study was to evaluate the potential association among PON1 activity and follicular growth, diameter of the preovulatory follicle and pregnancy per artificial insemination (AI) service in cattle. In Experiment 1, cows (n=33) were subjected to an estradiol-progesterone based protocol to control time of ovulation.

The acute effect of intravenous lipopolysaccharide injection on serum and intrafollicular HDL components and gene expression in granulosa cells of the bovine dominant follicle.

The aim of this study was to evaluate the effect of an acute systemic inflammatory response induced by lipopolysaccharide (LPS) in the serum and follicular fluid (FF) high-density lipoprotein (HDL) components, hormone concentrations and granulosa cell gene expression. For this purpose, twenty non-lactating Jersey dairy cows were submitted to a progesterone (P4) - estradiol (E2) based synchronization protocol. Cows received a single i.

Linoleic and α-linolenic fatty acid consumption over three generations exert cumulative regulation of hepatic expression of genes related to lipid metabolism.

The essential fatty acids, omega-3 and omega-6, consumed during pregnancy can benefit maternal and offspring health. For instance, they could activate a network of genes related to the nuclear receptor peroxisome proliferator-activated receptor α (Ppara) and sterol regulatory element binding transcription factor 1 (Srebf1), which play a role in fatty acid oxidation and lipogenesis. The present study aimed to investigate the effects of diets with different omega-3/omega-6 ratio consumed over three generations on blood biochemical parameters and hepatic expression of Ppara- and Srebf1-related genes.

Associations between resumption of postpartum ovarian activity, uterine health and concentrations of metabolites and acute phase proteins during the transition period in Holstein cows.

The resumption of ovarian activity, uterine health, severity of the negative energy balance and the synthesis of inflammatory mediators during the transition period in dairy cows are interrelated. Therefore, the aim of this study was to evaluate the association between the resumption of postpartum ovarian activity and the percentage of polymorphonuclear (PMN) cells in endometrial cytology, lipid mobilization and the secretion of acute phase proteins. For this study, 20 multiparous Holstein cows were used.

Predictive value of prepartum serum metabolites for incidence of clinical and subclinical mastitis in grazing primiparous Holstein cows.

The aim of this study was to measure changes in biochemical markers in the peripartum period of primiparous Holstein cows diagnosed with subclinical and clinical mastitis. In this study, 37 dairy cows were monitored daily during milking until 60 days postpartum and were categorized according to the occurrence of clinical mastitis (group mastitis (GM), n = 9) or subclinical mastitis (group subclinical mastitis (GSUB), n = 10) or absence of symptoms (control group (CG), n = 18). Blood samples were collected weekly from -30 to 60 days from calving.