Dexamethasone-induced eosinopenia is associated with lower progesterone production in cattle

Influence of Elective Cesarean Calving (with and without Dexamethasone Induction) on the Erythrogram and Iron Serum Profiles in Nellore Calves

Simple Summary

The use of elective cesarean section has become common practice in double muscled breeds of in vitro fertilized cattle and cloned calves, particularly before the onset of labor, when it is known that cesarean section negatively affects neonatal respiration and metabolic adaptation in humans and calves. However, there is a lack of information on the effects of cesarean section on the erythrogram of calves. The objectives of this study are to characterize the hematological profile of Nellore calves born spontaneously or by elective C-section (with or without induction with dexamethasone) and to verify the frequency of anemia in these animals. Our data indicate that in the first day of life there was a decrease in the number of red blood cells, hemoglobin rates, and values of the globular volume regardless of the type of birth; however, the recovery of these hematological values happened faster in zebu calves born spontaneously than in the group born by elective C-section (with or without induction). The results suggest that iron supplementation in the first month of life in Nellore calves that underwent cesarean section could be recommended to prevent the iron deficiency anemia observed in this study.

Abstract

The aim of the present study is to evaluate the erythrogram and iron serum profiles of neonatal calves born spontaneously or born by elective cesarean section with or without dexamethasone induction. The research was performed on 38 newborn Nellore calves. Three groups of calves were assigned according to the type of birth: calves born by spontaneous vaginal calving (n = 10), calves born by elective cesarean section without inducing labor (n = 14), and calves born by elective cesarean section with labor induction with dexamethasone (n = 14). Blood samples to assess red blood cell count (RBC), hemoglobin, hematocrit, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), concentration of mean corpuscular hemoglobin (MCHC), serum iron (SFe), total capacity to bind iron to transferrin (TIBIC), and transferrin saturation index (TSI) were performed at calving (0, 3, 6, and 12 h of life) and on 1, 2, 3, 5, 7, 10, 15, and 30 days of life. Regardless of the experimental group (calves born spontaneously, or born by elective cesarean section with or without dexamethasone induction), in the first day of life there was a decrease in the number of red blood cells, hemoglobin rates, and values of the globular volume. In the period of the first 10 days of life, animals from spontaneous vaginal delivery quickly recovered values of erythrocytes, hemoglobin, and packed cell volume, whereas animals born by elective C-section (induced and uninduced) did not recover as quickly in their rates of hemoglobin and packed cell volume values. In calves born by elective C-section (induced and uninduced), it was observed in their period between 10 and 30 days of life that the MCV and MCH were reduced by passing the presenting microcytic hypochromic when compared with calves obtained by spontaneous vaginal delivery. In the period between 10 and 30 days of life, the levels of SFe and TSI in animals born by elective C-section (induced and uninduced) are significantly lower. The differences in the erythrogram values between Nellore calves born spontaneously and those by elective C-section with or without induction must be considered consequent to the process of neonatal adaptation to extrauterine life. Iron supplementation in the first month of life in calves from cesarean could be recommended to prevent anemia of this iron deficiency.

Hypoxia-inducible factor-1alpha and nitric oxide synthases in bovine follicles close to ovulation and early luteal angiogenesis

The objective of the study was to characterize expression patterns of hypoxia-inducible factor-1alpha (HIF1A), inducible nitric oxide synthase (iNOS) and endothelial (eNOS) isoforms in time-defined follicle classes before and after GnRH application in the cow. Ovaries containing pre-ovulatory follicles or corpora lutea were collected by transvaginal ovariectomy (n = 5 cows/group) as follow: (I) before GnRH administration; (II) 4h after GnRH; (III) 10h after GnRH; (IV) 20h after GnRH; (V) 25h after GnRH; and (VI) 60h after GnRH (early corpus luteum). The mRNA abundance of HIF1A in the follicle group before GnRH was high, followed by a significant down regulation afterwards with a minimum level 25h after GnRH (close to ovulation) and significant increase only after ovulation. The mRNA abundance of iNOS before GnRH was high, decreased significantly during LH surge, with minimum levels afterwards. In contrast, the mRNA of eNOS decreased in the follicle group 20h after GnRH, followed by a rapid and significant upregulation just after ovulation. Immunohistochemically, the granulosa cells of antral follicles and the eosinophils of the theca tissue as well of the early corpus luteum showed a strong staining for HIF1A. The location of the eosinophils could be clearly demonstrated by immunostaining with an eosinophil-specific antibody (EMBP) and transmission electron microscopy. In conclusion, the parallel and acute regulated expression patterns of HIF1A and NOS isoforms, specifically during the interval between the LH surge and ovulation, indicate that these paracrine factors are involved in the local mechanisms, regulating final follicle maturation, ovulation and early luteal angiogenesis.

Effects of dexamethasone on growth, viability and ultrastructure of bovine secondary follicles cultured in vitro

This study aimed to evaluate the effects of dexamethasone on development, viability, antrum formation and ultrastructural integrity of bovine secondary follicles cultured in vitro for 18 days. Bovine ovaries were obtained from slaughterhouses and secondary follicles of ~150-200 µm diameter were isolated and cultured in the laboratory in TCM-199+ alone or supplemented with different concentrations of dexamethasone (1, 10, 100 and 1000 ng/ml). Follicle viability was evaluated after the culture period, using calcein-AM (viable) and ethidium homodimer (nonviable). Follicle diameters and antrum formation were evaluated at days 0, 6, 12 and 18. Before or after in vitro culture, follicles were fixed for histological and ultrastructural analysis. Follicle diameters were evaluated using analysis of variance and Kruskal-Wallis test, while chi-squared test was used to evaluate the percentage of viable follicles and antrum formation (P < 0.05). Follicles cultured for 6 days with all treatments increased their diameters significantly, but there was no significant difference between treatments at the end of the culture period. In vitro cultured follicles showed antral cavity formation at the end of the culture period, but no influence of dexamethasone was seen. Ultrastructural analysis showed that follicles cultured with dexamethasone (1, 10, 100 and 1000 ng/ml) had well preserved granulosa cells. However, oocytes from follicles cultured with 10, 100 or 1000 ng/ml dexamethasone showed signs of degeneration. It can be concluded that follicles cultured in vitro in the presence of dexamethasone demonstrated continuous in vitro growth, but oocytes from follicles cultured with 10, 100 or 1000 ng/ml dexamethasone had poor ultrastructure.

Contribution of the immune system to follicle differentiation, ovulation and early corpus luteum formation

Much of what we know about the involvement of the immune system in periovulatory follicle differentiation, ovulation and subsequent formation of the corpus luteum in cattle is drawn from the findings of studies in several mammalian livestock species. By integrating published histological data from cattle, sheep and pigs and referring back to the more comprehensive knowledge bank that exists for mouse and humans we can sketch out the key cells of the immune system and the cytokines and growth factors that they produce that are involved in follicle differentiation and luteinization, ovulation and early follicle development. These contributions are reviewed and the key findings, discussed.

Inflammation and angiogenesis in the corpus luteum

Angiogenesis is a very important process that helps establish and maintain the normal structure and function of the corpus luteum (CL). Early luteal development can be considered a kind of physiological injury with an inflammatory response; therefore, the inflammatory response may play an important role in the luteal angiogenesis. The inflammatory response is companied by activated leukocytes and their mediators. For luteal tissue, numerous activated leukocytes such as macrophages, neutrophils and eosinophils are present in the early luteal phase and are widely involved in neovascularization. The objective of this review is to describe the role of the inflammatory factors in the angiogenesis and to discuss their mechanism. Knowledge of action and mechanism of these inflammatory factors on angiogenic activity will be beneficial for the understanding of luteal function.

Productive and physiological responses of feeder cattle supplemented with Yucca schidigera extract during feedlot receiving

This experiment evaluated the effects of supplementing a saponin-containing feed ingredient, manufactured from purified extract of Yucca schidigera [Micro-Aid (MA); DPI Global; Porterville, CA], on performance, health, and physiological responses of receiving cattle. A total of 105 recently weaned Angus x Hereford calves (75 steers and 30 heifers), originating from eight cow-calf operations, were obtained from an auction facility on day -2 and road transported (800 km; 12 h) to the experimental facility. Immediately after arrival on day -1, shrunk BW was recorded and calves were grouped with free-choice access to grass hay, mineral supplement, and water. On day 0, calves were ranked by sex, source, and shrunk BW, and allocated to one of 21 pens (5 calves/pen; being one or two heifers within each pen). Pens were assigned to receive a total mixed ration (TMR) and one of three treatments (as-fed basis): (1) 1 g/calf daily of MA (M1; n = 7), (2) 2 g/calf daily of MA (M2; n = 7), or (3) no MA supplementation (CON; n = 7). Calves received the TMR to yield 15% (as-fed basis) orts, and treatments were top-dressed from days 0 to 59. Calves were assessed for bovine respiratory disease (BRD) signs and TMR intake was recorded for each pen daily. Calves were vaccinated against BRD pathogens on days 0 and 21. Final shrunk BW was recorded on day 60, and blood samples were collected on days 0, 2, 6, 10, 14, 21, 28, 34, 45, and 59. ADG was greater (P = 0.03) in M2 vs. M1 and CON (1.53, 1.42, and 1.42 kg/day, respectively), and similar (P = 0.95) between M1 and CON calves. No treatment effects were detected for TMR intake (P = 0.52), whereas feed efficiency was greater (P ≤ 0.05) in M2 vs. M1 and CON calves (213, 200, and 204 g/kg, respectively) and similar (P = 0.40) between M1 and CON calves. No treatment effects were detected (P = 0.39) for diagnosis of BRD signs. The number of antimicrobial treatments required upon BRD diagnosis was greater (P ≤ 0.01) in CON vs. M1 and M2 (1.40, 1.05, and 1.10 treatments, respectively), and similar (P = 0.60) between M1 and M2 calves. No other treatment effects were detected (P ≥ 0.23), including circulating concentrations of hormones and metabolites, serum antibody titers to BRD pathogens, and mRNA expression of innate immunity genes in whole blood. Collectively, results from this experiment suggest that MA supplementation at 2 g/animal daily enhances performance and response to BRD treatment in high-risk cattle during feedlot receiving.

Physiologic, health, and performance responses of beef steers supplemented with an immunomodulatory feed ingredient during feedlot receiving

One hundred eight Angus × Hereford steers, originating from 7 cow-calf were obtained from an auction yard on d -2 and transported by road (800 km; 12 h) to an experimental feedlot facility. Upon arrival on d -1, shrunk BW was recorded and steers were grouped with free-choice access to grass hay, mineral supplement, and water. On d 0, steers were ranked by source and shrunk BW and assigned to 1 of 18 pens (6 steers/pen). Pens were allocated to 1) no immunomodulatory ingredient supplementation during feedlot receiving (CON), 2) supplementation with OmniGen-AF (OMN; 22 g/steer daily, as-fed basis; Phibro Animal Health Corp., Teaneck, NJ) from d 0 to 30, or 3) 2 oral capsules of Stocker Immune Primer on d 0 + 15 g/steer daily (as-fed basis) of Stocker Preconditioned Premix (Ramaekers Nutrition, Santa Cruz, CA) from d 7 to 30 (IPF). From d 0 to 80, steers had free-choice access to grass hay and water and received a corn-based concentrate. Feed DMI was recorded from each pen, and steers were assessed for bovine respiratory disease (BRD) signs daily. Steers were vaccinated against BRD pathogens on d 0 and 21. Final shrunk BW was recorded on d 81, and blood samples were collected on d 0, 3, 7, 10, 14, 21, 31, 42, 56, and 73. Steer ADG and final BW were greater ( ≤ 0.05) in CON steers than in OMN and IPF steers (1.23, 0.76, and 1.06 kg/d [SEM 0.06], respectively, and 320, 282, and 307 kg [SEM 4], respectively) and ( < 0.01) in IPF steers than in OMN steers. No treatment effects were detected ( ≥ 0.76) for BRD incidence (66 ± 4%) and DMI, whereas G:F was greater ( < 0.01) in OMN steers than in CON steers. Mean plasma cortisol concentration was greater ( = 0.01) in CON steers than in OMN and IPF steers. Plasma haptoglobin concentrations tended ( = 0.10) to be greater in CON steers than in IPF steers on d 3, were greater ( = 0.04) in IPF steers than in CON steers on d 7, and tended ( = 0.10) to be less in OMN steers than in IPF and CON steers on d 21. Blood mRNA expression of was greater ( ≤ 0.05) in OMN and IPF steers than in CON steers on d 3 and in OMN steers than in CON and IPF steers on d 14. Blood mRNA expression of was greater ( ≤ 0.05) in OMN and IPF steers than in CON steers on d 10. Plasma IGF-I concentrations, serum antibody titers to BRD pathogens, and blood mRNA expression of , , , and did not differ ( ≥ 0.21) among treatments. Collectively, the immunomodulatory feed ingredients evaluated herein impacted adrenocortical and innate immune responses but failed to mitigate BRD incidence and improve performance of receiving cattle.

Expression pattern of HIF1alpha and vasohibins during follicle maturation and corpus luteum function in the bovine ovary

The aim of this study was to characterize expression patterns of hypoxia-inducible factor-1alpha (HIF1A) and vasohibin family members (VASH1 and VASH2) during different stages of ovarian function in cow. Experiment 1: Antral follicle classification occurred by follicle size and estradiol-17beta (E2) concentration in the follicular fluid into 5 groups (<0.5, 0.5-5, 5-40, 40-180 and >180 E2 ng/ml). Experiment 2: Corpora lutea (CL) were assigned to the following stages: days 1-2, 3-4, 5-7, 8-12, 13-16 and >18 (after regression) of oestrous cycle and of pregnancy (months 1-2, 3-4, 6-7, >8). Experiment 3: Cows on days 8-12 were injected with a prostaglandin F2alpha (PGF) analogue and CL were collected before and 0.5, 2, 4, 12, 24, 48 and 64 hr after PGF injection. Expression of mRNA was measured by qPCR, steroid hormone concentration by EIA and localization by immunohistochemistry. HIF1A mRNA expression in our study increases significantly in follicles during final maturation. The highest HIF1A mRNA expression was detected during the early luteal phase, followed by a significant decrease afterwards. In contrast, the mRNA of vasohibins in small follicle was high, followed by a continuous and significant downregulation in preovulatory follicles. The obtained results show a remarkable inverse expression and localization pattern of HIF1A and vasohibins during different stages of ovarian function in cow. These results lead to the assumption that the examined factors are involved in the local mechanisms regulating angiogenesis and that the interactions between proangiogenic (HIF1A) and antiangiogenic (vasohibins) factors impact all stages of bovine ovary function.

Localization of Vascular Endothelial Growth Factor and Fibroblast Growth Factor 2 in the Ovary of the Ostrich (Struthio camelus)

Vascular endothelial growth factor (VEGF) and fibroblast growth factor 2 (FGF-2) play a paramount role in the regulation of normal and pathologic angiogenesis in the ovary of mammals. Very little is known on the expression of these two growth factors in the avian ovary. The aim of this study was to determine for the first time the localization of VEGF and FGF-2 in the ovary of the ostrich using immunohistochemical techniques to investigate the vascularization of the rapidly growing huge ostrich oocyte. At the oocyte periphery, distinct VEGF-positive granules are visible. In our opinion, the expression of VEGF in the growing oocytes, which does not occur in mammals such as bovines, does not significantly contribute to angiogenesis in the theca interna and externa, where all the original and developing vessels are located, but may contribute to the mitoses and survival of granulosa cells during folliculogenesis. A different immunostaining can be demonstrated for FGF-2: from late pre-vitellogenic follicles, FGF-2 immunopositivity can be observed at the inner perivitelline layer area. In the stroma, the smooth muscle cells of small arteries and the endothelial cells of venules and veins are positively stained for FGF-2. Another interesting finding of this study is the occurrence of a significant number of VEGF- and FGF-2 positive heterophilic granulocytes within the ovarian stroma, which migrate from the periphery of the ovary towards the growing follicles. We assume that the growth factors of the heterophilic granulocytes contribute significantly to the angiogenesis seen in both theca layers.

CELL BIOLOGY SYMPOSIUM: perspectives: possible roles of polymorphonuclear neutrophils in angiogenesis and lymphangiogenesis in the corpus luteum during development and early pregnancy in ruminants

The establishment of pregnancy requires well-balanced regulation of the endocrine and immune systems and involves interactions among the conceptus, oviduct-uterus, and corpus luteum (CL). In particular, a rapid increase in plasma progesterone during the first week after ovulation is critical for the growth of the conceptus and successful pregnancy in cattle. Events involved in maternal recognition of pregnancy (MRP) may commence within 1 wk from AI, when interferon-stimulated gene expression in circulating polymorphonuclear neutrophils (PMN) increases in pregnant cows. To regulate optimal endocrine conditions within this time, the CL must develop rapidly, with active angiogenesis and lymphangiogenesis. The major angiogenic factors, vascular endothelial growth factor and fibroblast growth factor 2, contribute to the development of the CL but may also act as chemoattractants for PMN. Indeed, the number of PMN is greatest in the new CL, where PMN together with IL-8 induce active angiogenesis and lymphangiogenesis. During MRP, the conceptus secretes interferon tau (IFNT), which prevents CL regression by inhibiting luteolytic release of PGF2α from uterine endometrium. In addition, IFNT and PGE2 reach the CL and may contribute to desensitizing the CL to the luteolytic effects of PGF2α. In the bovine CL, lymphangiogenesis, stimulated by IFNT, may occur during MRP, and thus a shift of local immunity might occur at this timing. The aforementioned evidence supports the possible involvement of PMN in the establishment of pregnancy via CL regulation. Further investigation could expand our understanding of the communication between zygotes, PMN, and reproductive organs during early pregnancy. This should provide new insight into the contribution of neutrophils to CL function and immune tolerance during early pregnancy in ruminants.

Impact of angiogenic and innate immune systems on the corpus luteum function during its formation and maintenance in ruminants

The corpus luteum (CL) is formed from an ovulated follicle, and grows rapidly to secrete progesterone (P4) thereby supporting implantation and maintenance of pregnancy. It is now evident that angiogenesis is necessary to form the structure of the developing CL as well as to acquire the steroidogenic capacity to secrete large amounts of P4. It is of interest that the increases in CL size, plasma P4 concentration and luteal blood flow are occurring in parallel during the first seven days after ovulation. Angiogenic factors, such as vascular endothelial growth factor-A (VEGFA) and basic fibroblast growth factor (FGF2), play a central role in promoting cell proliferation and angiogenesis in the developing CL. Angiopoietins regulate the stability of blood vessels, which directly affects angiogenesis or angiolysis via angiogenic factors. Vasohibin-1 is a novel negative feedback regulator, which inhibits VEGF-based vasculogenesis. It became evident that the immune cells, i.e., macrophages, eosinophils and neutrophils are recruited into the CL - using the innate immune system - just after ovulation which is accompanied by bleeding. The immune cells support active angiogenesis and thus the growth of the CL. In cows, the lymphatic system, but not blood vascular system, is reconstituted during early pregnancy, and embryonic trophoblast-derived interferon tau could play a crucial role in inducing lymphangiogenesis. This novel phenomenon may support a maternal recognition of pregnancy in shifting the local systems in such a way that they ensure a long-term supply of P4 over the period of pregnancy. Overall, the current findings support the concept that several major components involved in the regulation of the CL development and maintenance overlap in stimulating steroidogenesis, angiogenesis, vascular function and the innate immune system.

Physiology and Endocrinology Symposium: role of immune cells in the corpus luteum

The immune system is essential for optimal function of the reproductive system. The corpus luteum (CL) is an endocrine organ that secretes progesterone, which is responsible for regulating the length of the estrous cycle, and for the establishment and maintenance of pregnancy in mammals. This paper reviews literature that addresses 2 areas; i) how immune cells are recruited to the CL, and ii) how immune cells communicate with luteal cells to affect the formation, development, and regression of the CL. Immune cells, primarily recruited to the ovulatory follicle from lymphoid organs after the LH surge, facilitate ovulation and populate the developing CL. During the luteal phase, changes in the population of macrophages, eosinophils, neutrophils, and T lymphocytes occur at critical functional stages of the CL. In addition to their role in facilitating ovulation, immune cells may have an important role in luteal function. Evidence shows that cytokines secreted by immune cells modulate both luteotropic and luteolytic processes. However, the decision to pursue either function may depend on the environment provided by luteal cells. It is suggested that understanding the role immune cells play could lead to identification of new strategies to improve fertility in dairy cattle and other species.