Metabolic profile of serum and follicular fluid from postpartum dairy cows during summer and winter

Evaluation of the expression of growth hormone and its receptor during the resumption of postpartum ovarian follicle development in dairy cows

Growth hormone is a key endocrine factor for metabolic adaptations to lactation and optimal reproductive function of the dairy cow. This study aimed to analyze the expression of GH and its receptor (GHR) in ovarian follicles, along with metabolic biomarkers, during the resumption of the postpartum follicular development, and to analyze the immunolocalization and protein expression of GH and GHR in preovulatory follicles. Thirty-six dairy cows were grouped according to the postpartum days (PPD) until the establishment of the first dominant follicle in: cows that established their first dominant follicle at fewer postpartum days (FPPD group; n = 15) and cows that established their first dominant follicle at more postpartum days (MPPD group; n = 22). For a second analysis, the same cows were regrouped according to the calving season (S), into cows calving in autumn (n = 20) and cows calving in winter (n = 17). During the PP, blood and follicular aspirates were obtained at two timepoints (T): when the first dominant follicle was established (T1, day 9 ± 2), and when the preovulatory follicle was established (T2, day 45 ± 2). Also, six dairy cows were ovariectomized in proestrus and ovarian histological sections were obtained. Growth hormone mRNA was detected in granulose cells from ovarian follicle sampled during PP. A PPD × T interaction was observed for GHR mRNA, where it was greater in the FPPD cows than in the MPPD cows at T1. Metabolic biomarkers and reproductive hormones showed differences or interaction between PPD, T, S, depending on the case. Also, GH and GHR were immunolocalized in granulosa and theca interna cells of preovulatory follicles. These results confirm the expression of GH and GHR in the mature ovarian follicles of dairy cows and show a possible association between greater GHR expression and an earlier resumption of postpartum follicular development.

Review: Reproductive consequences of whole-body adaptations of dairy cattle to heat stress

Heat stress has far-reaching ramifications for agricultural production and the severity of its impact has increased alongside the growing threats of global warming. Climate change is exacerbating the already-severe consequences of seasonal heat stress and is predicted to cause additional losses in reproductive performance, milk production and overall productivity. Estimated and predicted losses are staggering, and without advancement in production practices during heat stress, these projected losses will threaten the human food supply. This is particularly concerning as the worldwide population and, thus, demand for animal products grows. As such, there is an urgent need for the development of technologies and management strategies capable of improving animal production capacity and efficiency during periods of heat stress. Reproduction is a major component of animal productivity, and subfertility during thermal stress is ultimately the result of both reproductive and whole-body physiological responses to heat stress. Improving reproductive performance during seasonal heat stress requires a thorough understanding of its effects on the reproductive system as well as other physiological systems involved in the whole-body response to elevated ambient temperature. To that end, this review will explore the reproductive repercussions of whole-body consequences of heat stress, including elevated body temperature, altered metabolism and circulating lipopolysaccharide. A comprehensive understanding of the physiological responses to heat stress is a prerequisite for improving fertility, and thus, the overall productivity of dairy cattle experiencing heat stress.

Characterizing the follicular fluid metabolome: quantifying the correlation across follicles and differences with the serum metabolome

OBJECTIVE

To compare the variability in metabolomes between the serum and follicular fluid, as well as across 3 dominant follicles.

DESIGN

Prospective cohort study.

SETTING

An academic fertility clinic in the northeastern United States, 2005-2015.

PATIENTS

One hundred thirty-five women undergoing in vitro fertilization treatment who provided a serum sample during ovarian stimulation and up to 3 follicular fluid samples during oocyte retrieval.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Samples were analyzed using liquid chromatography with high-resolution mass spectrometry and 2 chromatography columns (C18 hydrophobic negative and hydrophilic interaction chromatography [HILIC] positive). We calculated overall, feature-specific, and subject-specific correlation coefficients to describe how strongly the intensity of overlapping metabolic features were associated between the serum and follicular fluid and between the 1st-2nd, 1st-3rd, and 2nd-3rd follicles. Feature-specific correlations were adjusted for age, body mass index, infertility diagnosis, ovarian stimulation protocol, and year.

RESULT(S)

From the C18-negative column and the high-resolution mass spectrometry, 7,830 serum features and 10,790 follicular fluid features were detected in ≥20% of samples. After screening retention times and checking for 1:1 matching, 1,928 features overlapped between the 2 metabolomes. From the HILIC-positive column and the high-resolution mass spectrometry, after applying the same exclusion criteria, there were 9,074 serum features, 5,542 follicular fluid features, and 1,149 features that overlapped. When comparing the feature intensity of overlapping metabolites in the serum and the follicular fluid, the overall (C18, 0.45; HILIC, 0.63), median feature-specific (C18, 0.35; HILIC, 0.37), and median subject-specific (C18, 0.42; HILIC, 0.59) correlations were low to moderate. In contrast, among the overlapping features across all 3 follicles, the overall (C18, all 0.99; HILIC, all 0.99), median feature-specific (C18, 0.74-0.81; HILIC, 0.79-0.85), and median subject-specific (C18, 0.88-0.89; HILIC, 0.90-0.91) correlations between follicular fluid metabolomics features within a woman were high.

CONCLUSION(S)

We observed minimal overlap and weak-to-moderate correlation between metabolomic features in the serum and follicular fluid but a large overlap and strong correlation between metabolomic features across follicles within a woman. The follicular fluid appears to represent a novel matrix, distinct from serum, which may be a rich source of biologic predictors of female fertility and reproductive outcomes.

Preovulatory serum estradiol concentration is positively associated with oocyte ATP and follicular fluid metabolite abundance in lactating beef cattle

Cattle induced to ovulate a small, physiologically immature preovulatory follicle had reduced oocyte developmental competence that resulted in decreased embryo cleavage and day 7 embryo quality compared with animals induced to ovulate a more advanced follicle. RNA-sequencing was performed on oocytes and their corresponding cumulus cells approximately 23 h after gonadotropin-releasing hormone (GnRH) administration to induce the preovulatory gonadotropin surge suggested reduced capacity for glucose metabolism and oxidative phosphorylation in the cumulus cells and oocytes from follicles ≤11.7 mm, respectively. We hypothesized that induced ovulation of a small, physiologically immature preovulatory follicle results in a suboptimal follicular microenvironment and reduced oocyte metabolic capacity. We performed a study with the objective to determine the impact of preovulatory follicle diameter and serum estradiol concentration at GnRH administration on oocyte metabolic competence and follicular fluid metabolome profiles. We synchronized the development of a preovulatory follicle and collected the follicle contents via transvaginal aspiration approximately 19 h after GnRH administration in lactating beef cows (n = 319). We determined ATP levels and mitochondrial DNA (mtDNA) copy number in 110 oocytes and performed ultra-high-performance liquid chromatography–high resolution mass spectrometry metabolomic studies on 45 follicular fluid samples. Intraoocyte ATP and the amount of ATP produced per mtDNA copy number were associated with serum estradiol concentration at GnRH and time from GnRH administration to follicle aspiration (P < 0.05). mtDNA copy number was not related to follicle diameter at GnRH, serum estradiol concentration at GnRH, or any potential covariates (P > 0.10). We detected 90 metabolites in the aspirated follicular fluid. We identified 22 metabolites associated with serum estradiol concentration at GnRH and 63 metabolites associated with follicular fluid progesterone concentration at the time of follicle aspiration (FDR < 0.10). Pathway enrichment analysis of significant metabolites suggested altered proteinogenesis, citric acid cycle, and pyrimidine metabolism in follicles of reduced estrogenic capacity pre-gonadotropin surge or reduced progesterone production by the time of follicle aspiration.

Time-lagged and acute impact of heat stress on production and fertility traits in the local dual-purpose cattle breed "Rotes Höhenvieh" under pasture-based conditions

Climate change causes rising temperatures and extreme weather events worldwide, with possible detrimental time-lagged and acute impact on production and functional traits of cattle kept in outdoor production systems. The aim of the present study was to infer the influence of mean daily temperature humidity index (mTHI) and number of heat stress days (nHS) from different recording periods on birth weight (BWT), 200 d- and 365 d-weight gain (200 dg, 365 dg) of calves, and on the probability of stillbirth (SB), and calving interval (CINT) of their dams. Data recording included 4,362 observations for BWT, 3,136 observations for 200 dg, 2,502 observations for 365 dg, 9,293 observations for the birth status, and 2,811 observations for CINT of the local dual-purpose cattle breed "Rotes Höhenvieh" (RHV). Trait responses on mTHI and nHS were studied via generalized linear mixed model applications with identity link functions for Gaussian traits (BWT, 200 dg, 365 dg, CINT) and logit link functions for binary SB. High mTHI and high nHS before autumn births had strongest detrimental impact on BWT across all antepartum- (a.p.) periods (34.4 ± 0.79 kg maximum). Prolonged CINT was observed when cows suffered heat stress (HS) before or after spring calvings, with maximum length of 391.6 ± 3.82 d (56 d a.p.-period). High mTHI and high nHS during the 42 d- and 56 d a.p.-period implied increased probabilities for SB. We found a significant (P < 0.05) seasonal effect on SB in model 3 across all a.p.-periods, with the highest probability in autumn (maximum of 5.4 ± 0.82% in the 7 d a.p.-period). Weight gains of calves (200 dg and 365 dg) showed strongest HS response for mTHI and nHS measurements from the long-term postnatal periods (42 d- and 56 d-periods), with minimum 200 dg of 194.2 ± 4.15 kg (nHS of 31 to 42 d in the 42 d-period) or minimum 365 dg of 323.8 ± 3.82 kg (mTHI ≥ 60 in the 42 d-period). Calves born in summer, combined with high mTHI or high nHS pre- or postnatal, had lower weight gains, compared with calves born in other calving seasons or under cooler conditions. Highest BWT, weight gains, and shortest CINT mostly were detected under cool to moderate climate conditions for mTHI, and small to moderate nHS. Results indicate acute and time-lagged HS effects and address possible HS-induced epigenetic modifications of the bovine genome across generations and limited acclimatization processes to heat, especially when heat occurs during the cooler spring and autumn months.

Effects of periconceptional heat stress on primiparous and multiparous daughters of Holstein dairy cows

To meet growing worldwide demands for animal products, animal production will need to increase in capacity and efficiency. Every opportunity to improve animal protein yield should be considered and explored. Developmental programming is one such opportunity that has not yet been thoroughly investigated in farm animal production. While developmental programming can be advantageous for the survival of the offspring, it is often described in conjunction with negative consequences. The known and potential causes and mechanisms are numerous, often stemming from some sort of stress experienced during the prenatal or early postnatal period. One stressor that is particularly concerning for farm animal production is heat stress. Heat stress is known to elicit adaptations associated with developmental programming in several species, but has not been investigated in dairy cattle until recently. Multiple studies have shown that heat stress experienced during the periconceptional period is generally associated with reduced milk production of resulting offspring. This could be the result of adaptations within the pre-ovulatory oocyte or early developing embryo. Interestingly, in a few select comparisons, periconceptional heat stress was associated with greater milk production. This was only observed when dairy cattle calved in the spring, and would therefore be reaching peak milk production in late spring or early summer (in heat stress). This is consistent with the match/mismatch theory associated with developmental programming, where matched prenatal/postnatal environments confer advantageous adaptations and mismatched prenatal/postnatal environments are generally detrimental to the offspring. While these studies are important additions to our growing knowledge of heat stress impacts on dairy cow production, the broader implication of developmental programming requires further investigation.

Effects of mineral supplementation on reproductive performance of pregnant cross-breed Bonsmara cows: An experimental study

Minerals in animal feed occur in variable structures, most of which determine the uptake and usage in biological processes in the body. Effective chemical breakdown of minerals may ensure efficient utilization in metabolism. The aim this study was to evaluate the effects of mineral supplementation on reproduction in cows. A farm was selected for the experiment due to the fact that it previously experienced different reproductive conditions in the farm. The farm comprises cross‐breed cows with Bonsmara dominating in the farm. Twelve pregnant primiparous and multiparous cows of different ages, parity and weight, that had previously experienced reproductive conditions, were randomly selected for this study. The cows were then randomly sub‐divided into two groups (experimental and control group) of six. The experimental group was injected with MULTIMIN™ + Se + Cu at a dosage of 1 ml/45 kg BW and Calci 50 p.i. at a dosage of 100–150 ml/500 kg BW at an interval of 6 weeks (from June to October 2017). Blood samples were collected before every injection date. The t test was used to relate the mean weight gain and serum metabolite between the experimental and control groups. The body weight gain was significantly higher in the experimental group compared to the non‐supplemented group. Supplemented cows had significantly (p < .05) high levels of triglycerides and creatinine kinase. A case of retained placenta and dystocia among non‐supplemented cows were noted. Thus, mineral supplementation can be used to improve productivity and reproductive well‐being.

Invited review: Management strategies capable of improving the reproductive performance of heat-stressed dairy cattle

Impaired fertility during periods of heat stress is the culmination of numerous physiological responses to heat stress, ranging from reduced estrus expression and altered follicular function to early embryonic death. Furthermore, heat-stressed dairy cattle exhibit a unique metabolic status that likely contributes to the observed reduction in fertility. An understanding of this unique physiological response can be used as a basis for improving cow management strategies, thereby reducing the negative effects of heat stress on reproduction. Potential opportunities for improving the management of dairy cattle during heat stress vary greatly and include feed additives, targeted cooling, genetic selection, embryo transfer and, potentially, crossbreeding. Previous studies indicate that dietary interventions such as melatonin and chromium supplementation could alleviate some of the detrimental effects of heat stress on fertility, and that factors involved in the methionine cycle would likely do the same. These supplements, particularly chromium, may improve reproductive performance during heat stress by alleviating insulin-mediated damage to the follicle and its enclosed cumulus-oocyte complex. Beyond feed additives, some of the simplest, yet most effective strategies involve altering the timing of feeding and cooling to take advantage of comparatively low nighttime temperatures. Likewise, expansion of cooling systems to include breeding-age heifers and dry cows has significant benefits for dams and their offspring. More complicated but promising strategies involve the calculation of breeding values for thermotolerance, the identification of genomic markers for heat tolerance, and the development of bedding-based conductive cooling systems. Unfortunately, no single approach can completely rescue the fertility of lactating dairy cows during heat stress. That said, region-appropriate combinations of strategies can improve reproductive measures to reasonable levels.

Expression of hepatic genes related to energy metabolism during the transition period of Holstein and F1 Holstein-Gir cows

The aim of this study was to investigate the expression of genes encoding enzymes and other factors involved with carbohydrate and lipid metabolism in the liver of 2 genetic groups of dairy cows during the transition period. We analyzed the expression of glucose-6-phosphatase (G6PC), cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C), methylmalonyl-CoA mutase (MUT), β-hydroxybutyrate dehydrogenase-2 (BDH2), acetyl-CoA carboxylase (ACC), carnitine palmitoyltransferase-2 (CPT2), 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), glucose transporter-2 (SLC2A2), and the transcription factor peroxisome proliferator-activated receptor α (PPARA). Blood concentrations of glucose, nonesterified fatty acids, and β-hydroxybutyrate were also determined. Liver biopsies and blood samples were taken at d 15 prepartum and at d 6, 21, 36, 51, and 66 postpartum from Holsteins (n = 6) and F₁ Holstein-Gir (n = 6) cows. Cows were kept under the same prepartum and postpartum management conditions. The results showed that the expression of G6PC, PEPCK-C, BDH2, ACC, CPT2, HMGCR, SLC2A2, and PPARA genes did not differ between genetic groups. Except for PEPCK-C, no interaction between genetic groups and the experimental period was observed. Within both groups of cows, G6PC and PEPCK-C gene expression decreased when comparing prepartum gene expression with 21 and 36 DIM, and increased in d 51 postpartum. MUT mRNA levels differed between the 2 genetic groups and displayed a significant increase after d 36 postpartum, whereas mRNA levels of HMGCR tended to increase when comparing d 21 and 36 to d 51 postpartum. Glucose concentrations also differed between genetic groups, being significantly higher in the plasma of F₁ Holstein-Gir cows than in Holstein cows, but no differences were found within each group during the analysis period. β-Hydroxybutyrate and nonesterified fatty acid concentrations did not differ between genetic groups, but displayed increased levels from prepartum to d 6 and 21 postpartum. Our results indicated that expression in the liver of genes involved with glucose and fatty acid metabolism were similar in both groups of cows and significant differences were observed between the 2 groups in the expression of MUT, a gene involved in propionate metabolism.

Effects of calving season on the voluntary waiting period and reproductive performance of Holstein cows in the tropical savannah

The effects of calving season [rainy (RS) and dry (DS)] on the voluntary waiting period (VWP) of 58 Holstein cows raised in the tropical savannah were investigated using data of temperature humidity index (THI), total antioxidant status (TAS), respiratory rate (RR), rectal temperature (RT), glucose, total cholesterol (TC), triglycerides (TG), velocity of uterine regression, and subsequent reproductive performance. Blood samples and clinical data were taken once every week, from calving until the sixth postpartum week. Reproductive data were collected until 180 days postpartum. THI differed between seasons (P < 0.05], as well as TAS (P < 0.001), RR (P < 0.001), RT (P < 0.01), glucose (P < 0.001), TC, and TG (P < 0.05), with higher values in RS. Although the velocity of uterine regression showed to be slower (P < 0.001) during RS, no differences were present regarding uterine health. Days open increased in RS (P < 0.001), but the number of services/conception was similar (P = 0.33). The results suggested cows under heat stress during the rainy season in the tropical savannah are more susceptible to a decline in the reproductive performance due to oxidative, metabolic, and uterine health problems.

Exploratory analysis of differences in sperm morphology in Nelore and Gir (Bos indicus) bulls

The aim of this study was to evaluate the effects of breed and season on semen quality parameters of zebu bulls. Data (1,632 registers) of semen production from Gir (n = 4) and Nelore (n = 15) bulls were collected between October 2005 and November 2009. The ejaculates were collected twice a week during various seasons (summer, fall, winter, and spring) and evaluated for the following semen parameters: ejaculate volume, sperm concentration, sperm motility, forward progressive motility (FPM), and sperm morphology. Factor analysis was used to determine the relationship among variables. The effect of breed (Gir and Nelore) and season and their cross effect on each parameter and extracted factor were tested using ANOVA. A negative correlation (P < 0.05) was observed between FPM and proximal droplet, as well as with abnormal loose head, abnormal small head, pouch formation, abnormal mid-piece, and strongly folded tail. Gir bull sperm showed more major defects, detached acrosome, and minor FPM (P < 0.01), whereas Nelore bulls showed a higher number of sperm with normally loose head.