Association between blood plasma urea nitrogen levels and reproductive fluid urea nitrogen and ammonia concentrations in early lactation dairy cows

Supplementation of rumen-protected lysine during the close-up period improves vaginal discharge clearance in Holstein dairy cows

We aimed to evaluate the effects of rumen-protected lysine (RPL) supplementation during the close-up period on uterine involution and the resumption of ovarian function in dairy cows. Fifty-two multiparous Holstein cows were categorized based on parity and expected calving date and randomly assigned to the RPL or control (CON) groups. The RPL group received 80 g of RPL daily from day 21 before the expected calving date until parturition. Blood samples were obtained twice weekly from pre-supplementation to 6 weeks postpartum. The onset of luteal activity postpartum was determined via ultrasonography twice weekly for up to 6 weeks postpartum. Uterine involution was tracked at 3 and 5 weeks postpartum through the vaginal discharge score, percentage of polymorphonuclear cells (PMN) in endometrial cytology samples, presence of intrauterine fluid, and gravid horn diameter via ultrasonography. Before supplementation, the RPL group showed amino acid imbalance, which was improved by RPL supplementation. There were no significant differences in the onset of luteal activity, percentage of PMN, intrauterine fluid, or the diameter of the uterine horn between the two groups. The vaginal discharge score in the RPL group decreased from 3 to 5 weeks postpartum, whereas that in the CON groups did not decrease. The number of cows with clinical endometritis was lower in the RPL group. Overall, RPL supplementation during the close-up period enhanced vaginal discharge clearance, potentially averting clinical endometritis, but did not affect the first ovulation in dairy cows.

Effect of Dietary Urea in Gestating Beef Cows: Circulating Metabolites, Morphometrics, and Mammary Secretions

Prolific use of supplementation strategies, including the utilization of urea, are practiced in beef cattle production systems. Unfortunately, the influence of urea supplementation on metabolics, adipose tissue mobilization, and mammary secretions is limited in beef cows. Therefore, the objectives of this experiment were to assess the influence of urea supplementation on metabolic profiles, morphometrics, and mammary secretions. Pregnant, multiparous beef cows were fed individually and assigned to treatment (n = 4/treatment) as Control or Urea Supplementation. Blood samples and body weight were collected every 28 d throughout gestation. Backfat thickness was measured via ultrasonography on days 28 and 280 of gestation. Total mammary secretions were sampled for composition. Concentrations of beta-hydroxybutyrate, non-esterified fatty acids, glucose, and plasma urea nitrogen did not differ by treatment. Body weight and backfat thickness changed in response to the progression of gestation, but did not differ between treatments. Finally, concentration of urea nitrogen increased in mammary secretions of cows fed urea, but total content of urea nitrogen in mammary secretions did not differ between treatments. In conclusion, we have demonstrated that the pregnant beef cow undergoes metabolic adaptation during gestation. However, urea supplementation failed to improve any of the morphometric parameters of the dams assessed.

Latest update on predictive indicators, risk factors, and 'Omic' technologies research of retained placenta in dairy cattle- review article

Retained placenta is a pathological condition defined as failure to expel fetal membranes within 12 -24h after parturition. It instigates important financial losses to the dairy industry causing considerable economic loss. It is a multifactorial disorder. Although different hypotheses have been proposed, contradictory results and no single factor explains the development of the disease. This indicates that there are overall significant gaps in our knowledge about the various factors affecting the etiopathology and pathobiology of the retained placenta. Thus, it will be of great interest to investigate the potential contributing factors that influence the occurrence of RP which provide us with the mechanisms to avoid the occurrence of the disease. In addition, different predictive indicators of RP should be part of our research, thus providing the essential procedures applied to deal with the disease and the development of novel therapeutic and prophylactic strategies in its management. Furthermore, lately, the molecular role takes attention to understanding its effect in the occurrence of the disease. Such information might help dairy scientists in the future to design better management and preventive practices for RP in dairy cows.

Supraphysiological concentration of urea affects the functional competence of Holstein-Friesian (Bos taurus) sperm

To understand the effects of urea on sperm functional attributes, fresh bull semen (n = 12) was subjected to four different concentrations (mg/mL) of urea to mimic the physiological (0.04 and 0.13), supraphysiological (0.43) concentrations and control (0 mg/mL). Sperm membrane integrity, kinematics, chromatin integrity, and mitochondrial membrane potential were assessed at different time points (before incubation, 0, 1, 2, and 4 h) of incubation. The concentration of urea in serum and seminal plasma was estimated and correlated with the ejaculate rejection rate and sperm functional attributes. The relative expression of urea transporter gene transcripts (UT-A and UT-B) was assessed in sperm and testis (control) using real-time PCR. The supraphysiological concentration of urea affected sperm kinematics, viability, functional membrane integrity, and acrosome integrity within 1 h of incubation (p < 0.05). Sperm head area decreased (p < 0.05) at 0 h and subsequently increased at 1 h of incubation in all media except supraphysiological (0.43 mg/dL) concentration of urea. Seminal plasma urea concentration showed a significant negative correlation with sperm motility, membrane integrity, and mitochondrial membrane potential (p < 0.05), but had a positive correlation with the ejaculate rejection rate (r = 0.69). Relative expression of the urea transporter genes revealed that UT-A was expressed only in the testis. In contrast, UT-B was expressed in both the testis and sperm, suggesting UT-B's role in regulating urea transport in sperm. At a supraphysiological level, urea adversely affected sperm functional attributes, osmoadaptation and may affect fertility.

Elevated blood urea nitrogen alters the transcriptome of equine embryos

High blood urea nitrogen (BUN) in cows and ewes has a negative effect on embryo development; however, no comparable studies have been published in mares. The aims of the present study were to evaluate the effects of high BUN on blastocoele fluid, systemic progesterone and Day 14 equine embryos. When a follicle with a mean (±s.e.m.) diameter of 25±3mm was detected, mares were administered urea (0.4g kg-1) with sweet feed and molasses (n=9) or sweet feed and molasses alone (control; n=10). Blood samples were collected every other day. Mares were subjected to AI and the day ovulation was detected was designated as Day 0. Embryos were collected on Day 14 (urea-treated, n=5 embryos; control, n=7 embryos). There was an increase in systemic BUN in the urea-treated group compared with control (P<0.05), with no difference in progesterone concentrations. There were no differences between the two groups in embryo recovery or embryo size. Urea concentrations in the blastocoele fluid tended to be higher in the urea-treated mares, with a strong correlation with plasma BUN. However, there was no difference in the osmolality or pH of the blastocoele fluid between the two groups. Differentially expressed genes in Day 14 embryos from urea-treated mares analysed by RNA sequencing were involved in neurological development, urea transport, vascular remodelling and adhesion. In conclusion, oral urea treatment in mares increased BUN and induced transcriptome changes in Day 14 equine embryos of genes important in normal embryo development.

Nanotechnology and Reproductive Management of Farm Animals: Challenges and Advances

Reproductive efficiency of farm animals has central consequences on productivity and profitability of livestock farming systems. Optimal reproductive management is based on applying different strategies, including biological, hormonal, nutritional strategies, as well as reproductive disease control. These strategies should not only guarantee sufficient reproductive outcomes but should also comply with practical and ethical aspects. For example, the efficiency of the biological- and hormonal-based reproductive strategies is mainly related to several biological factors and physiological status of animals, and of nutritional strategies, additional factors, such as digestion and absorption, can contribute. In addition, the management of reproductive-related diseases is challenged by the concerns regarding the intensive use of antibiotics and the development of antimicrobial resistant strains. The emergence of nanotechnology applications in livestock farming systems may present innovative and new solutions for overcoming reproductive management challenges. Many drugs (hormones and antibiotics), biological molecules, and nutrients can acquire novel physicochemical properties using nanotechnology; the main ones are improved bioavailability, higher cellular uptake, controlled sustained release, and lower toxicity compared with ordinary forms. In this review, we illustrate advances in the most common reproductive management strategies by applying nanotechnology, considering the current challenges of each strategy.

Epidermal growth factor alleviates the negative impact of urea on frozen-thawed bovine sperm, but the subsequent developmental competence is compromised

Upon insemination, sperm cells are exposed to components of the female reproductive tract (FRT) fluids, such as urea and epidermal growth factor (EGF). It has been shown that both urea and EGF use EGF receptor signaling and produce reactive oxygen species (ROS) that are required at certain levels for sperm capacitation and acrosome reaction. We therefore hypothesized that during bovine sperm capacitation, a high level of urea and EGF could interfere with sperm function through overproduction of ROS. High-level urea (40 mg/dl urea is equal to 18.8 mg/dl of blood urea nitrogen) significantly increased ROS production and TUNEL-positive sperm (sperm DNA fragmentation, sDF) percentage, but decreased HOS test score, progressive motility, acrosome reaction and capacitation. The EGF reversed the negative effects of urea on all sperm parameters, with the exception of ROS production and DNA fragmentation, which were higher in urea-EGF-incubated sperm than in control-sperm. The developmental competence of oocytes inseminated with urea-EGF-incubated sperm was significantly reduced compared to the control. A close association of ROS production or sDF with 0-pronuclear and sperm non-capacitation rates was found in the network analysis. In conclusion, EGF enhanced urea-reduced sperm motility; however, it failed to reduce urea-increased sperm ROS or sDF levels and to enhance subsequent oocyte competence. The data suggests that any study to improve sperm quality should be followed by a follow-up assessment of the fertilization outcome.

Relationships between blood and follicular fluid urea nitrogen concentrations and between blood urea nitrogen and embryo survival in mares

High blood urea nitrogen (BUN) concentration is linked to low fertility in cows and ewes; however, this relationship has not been reported in mares. The study characterized the relationship between BUN and follicular fluid urea nitrogen (FUN) during follicle growth (Experiment 1) and the impact of BUN from embryo donors on the pregnancy outcome of recipient mares (Experiment 2). In experiment one, follicular fluid and blood samples were collected from mares during diestrus with growing follicles and during estrus with pre-ovulatory follicles (n = 16 and 10 mares, respectively). In experiment two, BUN concentrations of embryo donors were related to pregnancy outcome after embryo transfer. In experiment one, there was a strong positive correlation between BUN and FUN (R = 0.83; P < 0.0001), with higher BUN in mares with growing follicles than with preovulatory follicles (P = 0.004) and higher FUN in growing follicles than in preovulatory follicles (P = 0.031). In experiment two, BUN was higher in donor mares that produced unsuccessful embryos compared to donor mares that produced embryos resulting in successful pregnancies at D14 (P < 0.03). Additionally, there was an effect of age (P = 0.01) and interaction between age and lactation (P = 0.009) in donor mares for embryo survival after embryo transfer. Donor mares with unsuccessful embryos were older than donor mares with successful embryos. Therefore, these experiments showed that BUN was related to follicular fluid environment as well as to the survival of Day 7-8 embryos after transfer to recipient mares.

Effect of protein supplement level on the productive and reproductive parameters of replacement heifers managed in intensive grazing systems

Evaluations of replacement heifers in intensively managed grazing systems in tropical conditions are warranted. Thus, we aimed to evaluate performance, muscle and mammary gland development, oocyte quality, and in vitro production of embryos of crossbred heifers grazing an intensively managed pasture and supplemented with high or low protein concentrates. Eighteen pubertal crossbred heifers (Holstein x Gyr) with an initial weight of 350 ± 8.0 kg were used in a 60-day trial. Two supplement types, 12% crude protein (CP) (S12CP) or 24% CP (S24CP), and a control treatment (mineral mixture, CON) were randomly distributed to the heifers. Throughout the experiment, four digestibility trials were performed over four consecutive days. Four ovarium pick-ups were performed to evaluate oocyte quality and in vitro embryo production. Lastly, ultrasounds of carcasses and mammary glands were performed. The intakes of dry matter (DM), digestible energy (DE), and CP were greater for supplemented (SUP) compared with CON heifers. The SUP heifers had a greater average daily gain (ADG) (645 versus 390 g/d) and rib eye area (58.78 versus 53.32 cm2) than the CON heifers. Oocyte recovery, quality, and follicle features were not affected by supplementation strategy. However, the cleavage rate (47.17% versus 30.31%) and blastocyst rate (27.91% versus 10.12%) were negatively affected by supplementation. The S12CP presented a blastocyst rate much lower than the S24CP (3.02% versus 17.23%). Carcass ultrasonography indicated a trend for greater rib eye area for S24CP and mammary ultrasonography indicated no effects of supplementation on mammary gland development. In summary, supplementation seems to be an appropriate strategy for satisfactory performance, with greater muscle deposition and no negative impacts on mammary gland development. However, in vitro embryo production was impaired when the animals received the supplementation with 12% CP.

Assisted reproductive technologies for endangered species conservation: developing sophisticated protocols with limited access to animals with unique reproductive mechanisms

Assisted reproductive technologies (ARTs) have been proposed as a means of overcoming the significant challenges of managing small, isolated populations of endangered species in zoos. However, efficient protocols for ARTs do not exist for most endangered species. This review will focus on research efforts to characterize unique reproductive mechanisms and develop species-specific ARTs. Central to these studies are assays to measure steroid metabolites in urine or feces and/or training programs to allow unrestrained blood collections and ultrasound evaluations. The resulting information about estrous cycle dynamics, combined with studies of semen collection and processing, provides the foundation for the development of artificial insemination (AI). In vitro fertilization and embryo transfer are also discussed in relation to the advantages these techniques could provide relative to AI, as well as the significant challenges involved with technologies that require oocytes and embryos. Finally, an argument is made for additional research of nontraditional model species (e.g., domestic cats and dogs) and the development of novel models representing unique taxa. Whether these species are studied by zoo-based researchers with the expressed intent of developing ARTs for conservation or academic scientists interested in basic biology, the resulting information will provide a unique, evolutionary perspective on reproduction that could have wide-reaching benefits. The more information we have available, the better our chances will be of developing effective ARTs and making a difference in conservation efforts for endangered species.

Effects of corn supplementation and age on performance and reproduction of beef females grazing lush spring pasture

This study evaluated how corn supplementation and age of female affected body weight (BW), body condition score (BCS), artificial insemination (AI) pregnancy rate, and blood metabolites (nonesterified fatty acid [NEFA], β-hydroxybutyrate [BHBA], and blood urea nitrogen [BUN]) when grazing lush spring pasture. Angus and Angus × Simmental beef females (n = 361) were blocked by location, stratified by BW and BCS, and then were assigned to groups (n = 8 groups/treatment combination; 9–14 females/group). The study utilized a stratified, randomized complete block design with a 2 × 2 factorial arrangement of treatments. The four treatment combinations were: yearling heifers receiving no supplement (CON-H); yearling heifers receiving supplement of dry-rolled corn (SUPP-H; 1.81 kg as-fed/heifer/d) for 42 d; 2-yr-old lactating cow-calf pairs receiving no supplement (CON-C); and 2-yr-old lactating cow-calf pairs receiving supplement of dry-rolled corn (SUPP-C; 1.81 kg as-fed/cow/d) for 42 d. Supplementation began at AI (end of April) when cows began grazing tall fescue (Festuca arundinacea schreb)-red clover (Trifolium pratense) pastures. Pasture forage was collected weekly for analysis. Throughout the study, forage crude protein decreased (P < 0.01) over time, but acid detergent fiber (ADF), neutral detergent fiber, dry matter, forage height, and forage mass all increased (P < 0.01) over time. Females receiving SUPP tended (P = 0.10) to have greater BW and greater BW change over the supplementation period. Supplementation × age effects for BCS were detected (P = 0.04); SUPP-H had greater BCS than all other treatment combinations at d 42. Cow BHBA was greater (P < 0.01) compared with heifers. Female NEFA increased (P < 0.01) from d 12 to 42. Control females had greater (P = 0.02) serum NEFA concentrations compared with SUPP females. Control females had greater (P = 0.03) BUN concentrations compared with SUPP females. Cow BUN was greater (P < 0.01) than heifer BUN. Supplementation effects were not detected (P ≥ 0.25) for AI or overall pregnancy rate. In conclusion, there were no supplementation × age interactions excluding d 42 BCS. Supplementation regardless of female age tended to improve d 42 BW and BW change. Cow BHBA and BUN was greater compared with the heifers, whereas the supplemented females had decreased NEFA and BUN. Cows tended to have greater AI pregnancy rates than heifers, but supplementation did not affect AI or overall pregnancy rates.

A High Protein Model Alters the Endometrial Transcriptome of Mares

High blood urea nitrogen (BUN) decreases fertility of several mammals; however, the mechanisms have not been investigated in mares. We developed an experimental model to elevate BUN, with urea and control treatments (7 mares/treatment), in a crossover design. Urea-treatment consisted of a loading dose of urea (0.03 g/kg of body weight (BW)) and urea injections over 6 hours (0.03 g/kg of BW/h). Control mares received the same volume of saline solution. Blood samples were collected to measure BUN. Uterine and vaginal pH were evaluated after the last intravenous infusion, then endometrial biopsies were collected for RNA-sequencing with a HiSeq 4000. Cuffdiff (2.2.1) was used to identify the differentially expressed genes (DEG) between urea and control groups (false discovery rate-adjusted p-value < 0.1). There was a significant increase in BUN and a decrease of uterine pH in the urea group compared to the control group. A total of 193 genes were DEG between the urea and control groups, with five genes identified as upstream regulators (ETV4, EGF, EHF, IRS2, and SGK1). The DEG were predicted to be related to cell pH, ion homeostasis, changes in epithelial tissue, and solute carriers. Changes in gene expression reveal alterations in endometrial function that could be associated with adverse effects on fertility of mares.

Understanding the hidden relations between pro- and anti-inflammatory cytokine genes in bovine oviduct epithelium using a multilayer response surface method

An understanding gene-gene interaction helps users to design the next experiments efficiently and (if applicable) to make a better decision of drugs application based on the different biological conditions of the patients. This study aimed to identify changes in the hidden relationships between pro- and anti-inflammatory cytokine genes in the bovine oviduct epithelial cells (BOECs) under various experimental conditions using a multilayer response surface method. It was noted that under physiological conditions (BOECs with sperm or sex hormones, such as ovarian sex steroids and LH), the mRNA expressions of IL10, IL1B, TNFA, TLR4, and TNFA were associated with IL1B, TNFA, TLR4, IL4, and IL10, respectively. Under pathophysiological + physiological conditions (BOECs with lipopolysaccharide + hormones, alpha-1-acid glycoprotein + hormones, zearalenone + hormones, or urea + hormones), the relationship among genes was changed. For example, the expression of IL10 and TNFA was associated with (IL1B, TNFA, or IL4) and TLR4 expression, respectively. Furthermore, under physiological conditions, the co-expression of IL10 + TNFA, TLR4 + IL4, TNFA + IL4, TNFA + IL4, or IL10 + IL1B and under pathophysiological + physiological conditions, the co-expression of IL10 + IL4, IL4 + IL10, TNFA + IL10, TNFA + TLR4, or IL10 + IL1B were associated with IL1B, TNFA, TLR4, IL10, or IL4 expression, respectively. Collectively, the relationships between pro- and anti-inflammatory cytokine genes can be changed with respect to the presence/absence of toxins, sex hormones, sperm, and co-expression of other gene pairs in BOECs, suggesting that considerable cautions are needed in interpreting the results obtained from such narrowly focused in vitro studies.

Association between milk urea nitrogen and first service conception in smallholder dairy farms under heat and humidity stress

Aim:

The study was to evaluate the relationship between the first service conception (FSC) and milk urea nitrogen (MUN) in smallholder dairy farms under heat and humidity stress.

Materials and Methods:

Dairy cows from 43 dairy farms giving birth between November 2014 and April 2015 (n=295) contributed to the study. All cows were sampled monthly to measure milk compositions, and we collected additional farm data from farmers through a questionnaire. The first service during the first 120 days of lactation was the outcome of interest in this study. Multivariable logistic regression determined significant associations with FSC.

Results:

The overall FSC was 22% and the mean MUN concentration was 11.55 mg/dl. The final FSC model included MUN concentration, the season of breeding, and protein energy ratio (PE ratio) in the diet. The odds of FSC were reduced by approximately 10% for each mg/dl higher MUN on the day of the milk sample that was nearest to the artificial insemination (AI) day. The odds of FSC were nearly 3 times higher when the first insemination occurred in winter compared to summer first services. Taking into account the nutritional factors, the odds of FSC were nearly 70% higher with an increase in PE ratio of 10 g of crude protein/Mcal from the mean of 35.90 g.

Conclusion:

This study of smallholder dairy farmers in the hot and humid climate of Thailand confirmed that season, nutritional management, and MUN concentration were associated with FSC. MUN appears to be a useful indicator to monitor the effects of diet on reproductive performance from this study.

Urea influences amino acid turnover in bovine cumulus-oocyte complexes, cumulus cells and denuded oocytes, and affects in vitro fertilization outcome

High-protein diets often lead to an increase in urea concentration in follicular fluid of dairy cows, which may reduce oocyte competence. In the present study, maturation media were supplemented with urea (0, 20, 40 mg/dl), and amino acids (AAs) turnover was evaluated in the 24-h spent media of specimens (cell types), bovine cumulus-oocyte complexes (COCs), cumulus cells (CCs), or denuded oocytes (DOs). The main effects of urea and cell type, and their interaction were significant on the individual turnover (expect threonine, glycine, and tyrosine) and total turnover, depletion, and appearance of AAs. The results showed a high level of urea and DOs increased the depletion of all AAs and that of essential and non-AAs, respectively. Sensitivity analysis revealed the highest sensitivity of isoleucine, lysine, and tryptophan to urea, especially in DOs. Principal component analysis (PCA) evaluated the strong correlations between the turnover of: (1) glutamine, aspartic acid or glycine, and developmental competence and fertilization of COCs; (2) serine, isoleucine, valine or glutamic acid, and cleavage rate of DOs; and (3) serine, glutamine, aspartic acid or alanine, and CCs viability. In conclusion, urea significantly changed the turnover of AAs by COCs, CCs and DOs, and reduced the subsequent developmental competence of bovine oocytes.

Relationship of vaginal discharge characteristics evaluated by Metricheck device to metabolic status in postpartum dairy cows

The relationship between vaginal discharge characteristics and metabolic status has been studied in postpartum dairy cows. Vaginal discharges at 2-6 weeks postpartum were scored weekly on a 1 (clear) to 5 (purulent material with stench) scale using the Metricheck device and classified into three groups as follows: Endometritis group (n = 19), greater than or equal to score 4 until 3 weeks postpartum; Delayed involution group (n = 9), score 2 or 3 after having score 1; Healthy group (n = 23), cows except those belonging to the Delayed involution and Endometritis groups. The uterus and cervix were assessed using ultrasonography. Blood samples were collected twice weekly from 1 to 6 weeks postpartum from all cows and were additionally obtained for 13,14-dihydro-15-keto-prostaglandin F2α (PGFM) measurements from multiparous cows. Cows with delayed involution had delayed onset of luteal activity (p < 0.05) and higher serum urea nitrogen (BUN) concentrations (p < 0.01) than healthy animals. Cows with endometritis had more peripartum diseases (p < 0.05), lower milk yield (p < 0.05), longer cervix diameter (p < 0.05), and lower serum albumin (p < 0.01), total cholesterol (p < 0.01), and magnesium (p < 0.01) concentrations, and higher aspartate aminotransferase levels (p < 0.05) than healthy cows. Plasma PGFM concentrations tended to be higher in the Delayed involution group (p = 0.083) and lower in the Endometritis group (p = 0.085) than in the Healthy group. In summary, delayed involution was shown to be associated with higher BUN concentration, and endometritis may have been caused by peripartum diseases and hepatic dysfunction.

Urea changes oocyte competence and gene expression in resultant bovine embryo in vitro

SummaryNutrition influences the microenvironment in the proximity of oocyte and affects early embryonic development. Elevated blood urea nitrogen, even in healthy dairy cows, is associated with reduced fertility and there is high correlation between blood urea levels and follicular fluid urea levels. Using a docking calculation (in silico), urea showed a favorable binding activity towards the ZP-N domain of ZP3, that of ZP2, and towards the predicted full-length sperm receptor ZP3. Supplementation of oocyte maturation medium with nutrition-related levels of urea (20 or 40 mg/dl as seen in healthy dairy cows fed on low or high dietary protein, respectively) dose-dependently increased: (i) the proportion of oocytes that remained uncleaved; and (ii) oocyte degeneration; and reduced cleavage, blastocyst and hatching rates. High levels of urea induced shrinkage in oocytes, visualised using scanning electron microscopy. Urea downregulated NANOG while dose-dependently upregulating OCT4, DNMT1, and BCL2 expression. Urea at 20 mg/dl induced BAX expression. Using mathematical modelling, the rate of oocyte degeneration was sensitive to urea levels; while cleavage, blastocyst and hatching rates exhibited negative sensitivity. The present data imply a novel role for urea in reducing oocyte competence and changing gene expression in the resultant embryos.

Metabolic profiles of cow's blood; a review

The term 'metabolic profile' refers to the analysis of blood biochemical parameters that are useful to assess and prevent metabolic and nutritional disorders in dairy herds. In the higher standards of milk production, the priority in modern breeding is keeping dairy cows in high lactation and healthy. The proper analysis, as well as control. of their feeding and metabolic status is immensely important for the health condition of the herd. The disproportion between the genetically determined ability for milk production and the limitations in improving the energy value of the ration may be the cause of metabolic disorders. Negative energy balance has a major impact on the body's hormonal balance and organ functions and mostly appears during transition periods: from 3 to 2 weeks prepartum until 2-3 weeks postpartum. The term 'transition' is used to underscore the important physiological, metabolic and nutritional changes occurring in this time. The manner in which these changes occur and how they are diagnosed and detected are extremely important, as they are closely related to clinical and subclinical postpartum diseases, lactation and reproductive performance - factors that significantly shape the profitability of production. Therefore the priority for intensive milk production is prevention of metabolic diseases and other disorders. It is the intent of this review to synthesize and summarize the information currently available on metabolic status and physiological changes in the cow's body that occur during lactation, as well as to discuss the interpretation of the results, which will be a useful diagnostic tool in nutritional evaluations of the dairy herd. © 2016 Society of Chemical Industry.

Short communication: Urea induces T helper 2 (Th2) type environment at transcriptional level and prostaglandin E2 secretion in bovine oviduct epithelial cells in culture

Excess dietary protein intake in early lactation dairy cows resulting in blood urea nitrogen of greater than 19 to 20mg/dL is associated with decreased fertility. Little is known about the local interference of urea in the normal immunological environment of the oviduct that provides optimal conditions for early reproductive events. A bovine oviduct epithelial cell (BOEC) culture was used to determine how urea influences immune environment. The BOEC monolayer was supplemented with low (20mg/dL) and high (40mg/dL) concentrations of urea together with ovarian steroids, estradiol (1ng/mL) and progesterone (1ng/mL), and LH (10ng/mL) at concentrations observed during the preovulatory period. The urea values used in this study were equivalent to 9.3 and 18.7mg/dL of blood urea nitrogen, which are typically common in lactating dairy cows with low or high protein intake, respectively. Stimulation of BOEC with 40mg/dL of urea induced gene expression of IL10 and IL4, epithelial-derived T helper type 2-driving (anti-inflammatory) cytokines as well as mPGES-1 expression and prostaglandin E2 (PGE2) secretion. However, urea concentrations of both 20 and 40mg/dL failed to alter the expression of IL1B and TNFA, Th1-driving cytokines, and the gene expression of TLR4. However, a concentration of 40mg/dL of urea stimulated α 1-acid glycoprotein expression, an acute phase protein. Data from this in vitro study suggest that urea, at least in part, contributes to influence the expression of some immune-related genes toward T helper type 2 type and prostaglandin E2 secretion, leading to disruption in local environment for fertilization and early embryonic development.

Characterization of the bovine milk proteome in early-lactation Holstein and Jersey breeds of dairy cows

Milk is a highly nutritious natural product that provides not only a rich source of amino acids to the consumer but also hundreds of bioactive peptides and proteins known to elicit health-benefitting activities. We investigated the milk protein profile produced by Holstein and Jersey dairy cows maintained under the same diet, management and environmental conditions using proteomic approaches that optimize protein extraction and characterization of the low abundance proteins within the skim milk fraction of bovine milk. In total, 935 low abundance proteins were identified. Gene ontology classified all proteins identified into various cellular localization and function categories. A total of 43 low abundance proteins were differentially expressed between the two dairy breeds. Bioactive proteins involved in host-defense, including lactotransferrin (P=0.0026) and complement C2 protein (P=0.0001), were differentially expressed by the two breeds, whereas others such as osteopontin (P=0.1788) and lactoperoxidase (P=0.2973) were not. This work is the first to outline the protein profile produced by two important breeds of dairy cattle maintained under the same diet, environment and management conditions in order to observe likely true breed differences. This research now allows us to better understand and contrast further research examining the bovine proteome that includes these different breeds.

BIOLOGICAL SIGNIFICANCE

Within the last decade, the amount of research characterizing the bovine milk proteome has increased due to growing interest in the bioactive proteins that are present in milk. Proteomic analysis of low abundance whey proteins has mainly focused on human breast milk; however, previous research has highlighted the presence of bioactive proteins in bovine milk. Recent publications outlining the cross-reactivity of bovine bioactive proteins on human biological function highlight the need for further investigation into the bovine milk proteome. The rationale behind this study is to characterize and compare the low abundance protein profile in the skim milk fraction produced from Holstein and Jersey breeds of dairy cattle, which are two major dairy cattle breeds in the USA. A combination of fractionation strategies was used to efficiently enrich the low abundance proteins from bovine skim milk for proteomic profiling. A total of 935 low abundance proteins were identified and compared between the two bovine breeds. The results from this study provide insight into breed differences and similarities in the milk proteome profile produced by two breeds of dairy cattle.

Relationships between Circulating Urea Concentrations and Endometrial Function in Postpartum Dairy Cows

Simple Summary

Dairy cows fed high levels of protein to increase milk yield tend to have reduced fertility but the reasons behind this are unclear. Differing dietary protein levels are reflected in altered urea concentrations in both blood and other tissues including the uterus. We showed that the circulating urea concentration was highly correlated to changed expression levels of many genes in the endometrium shortly after calving. These were predominantly associated with tissue repair, innate immunity and lipid metabolism. A subsequent study found no effect of altered urea concentration on endometrial gene expression in vitro implying that the dietary influence is indirect.

Abstract

Both high and low circulating urea concentrations, a product of protein metabolism, are associated with decreased fertility in dairy cows through poorly defined mechanisms. The rate of involution and the endometrial ability to mount an adequate innate immune response after calving are both critical for subsequent fertility. Study 1 used microarray analysis to identify genes whose endometrial expression 2 weeks postpartum correlated significantly with the mean plasma urea per cow, ranging from 3.2 to 6.6 mmol/L. The biological functions of 781 mapped genes were analysed using Ingenuity Pathway Analysis. These were predominantly associated with tissue turnover (e.g., BRINP1, FOXG1), immune function (e.g., IL17RB, CRISPLD2), inflammation (e.g., C3, SERPINF1, SERPINF2) and lipid metabolism (e.g., SCAP, ACBD5, SLC10A). Study 2 investigated the relationship between urea concentration and expression of 6 candidate genes (S100A8, HSP5A, IGF1R, IL17RB, BRINP1, CRISPLD2) in bovine endometrial cell culture. These were treated with 0, 2.5, 5.0 or 7.5 mmol/L urea, equivalent to low, medium and high circulating values with or without challenge by bacterial lipopolysaccharide (LPS). LPS increased S100A8 expression as expected but urea treatment had no effect on expression of any tested gene. Examination of the genes/pathways involved suggests that plasma urea levels may reflect variations in lipid metabolism. Our results suggest that it is the effects of lipid metabolism rather than the urea concentration which probably alter the rate of involution and innate immune response, in turn influencing subsequent fertility.

Effects of protein supplementation frequency on physiological responses associated with reproduction in beef cows

The objective of this experiment was to determine if frequency of protein supplementation impacts physiological responses associated with reproduction in beef cows. Fourteen nonpregnant, nonlactating beef cows were ranked by age and BW and allocated to 3 groups. Groups were assigned to a 3 × 3 Latin square design, containing 3 periods of 21 d and the following treatments: 1) soybean meal supplementation daily (D), 2) soybean meal supplementation 3 times/week (3WK), and 3) soybean meal supplementation once/week (1WK). Within each period, cows were assigned to an estrus synchronization protocol: 100 μg of GnRH + controlled internal drug release device (CIDR) containing 1.38 g of progesterone (P4) on d 1, 25 mg of PGF2α on d 8, and CIDR removal + 100 μg of GnRH on d 11. Grass-seed straw was offered for ad libitum consumption. Soybean meal was individually supplemented at a daily rate of 1 kg/cow (as-fed basis). Moreover, 3WK was supplemented on d 0, 2, 4, 7, 9, 11, 14, 16, and 18 whereas 1WK was supplemented on d 4, 11, and 18. Blood samples were collected from 0 (before) to 72 h after supplementation on d 11 and 18 and analyzed for plasma urea-N (PUN). Samples collected from 0 to 12 h were also analyzed for plasma glucose, insulin, and P4 (d 18 only). Uterine flushing fluid was collected concurrently with blood sampling at 28 h for pH evaluation. Liver biopsies were performed concurrently with blood sampling at 0, 4, and 28 h and analyzed for mRNA expression of carbamoyl phosphate synthetase I (CPS-I; h 28) and CYP2C19 and CYP3A4 (h 0 and 4 on d 18). Plasma urea-N concentrations were greater (P < 0.01) for 1WK vs. 3WK from 20 to 72 h and greater (P < 0.01) for 1WK vs. D from 16 to 48 h and at 72 h after supplementation (treatment × hour interaction, P < 0.01). Moreover, PUN concentrations peaked at 28 h after supplementation for 3WK and 1WK (P < 0.01) and were greater (P < 0.01) at this time for 1WK vs. 3WK and D and for 3WK vs. D. Expression of CPS-I was greater (P < 0.01) for 1WK vs. D and 3WK. Uterine flushing pH tended (P ≤ 0.10) to be greater for 1WK vs. 3WK and D. No treatment effects were detected (P ≥ 0.15) on expression of CYP2C19 and CYP3A4, plasma glucose, and P4 concentrations, whereas plasma insulin concentrations were greater (P ≤ 0.03) in D and 3WK vs. 1WK. Hence, decreasing frequency of protein supplementation did not reduce uterine flushing pH or plasma P4 concentrations, which are known to impact reproduction in beef cows.

Potential role of N-carbamoyl glutamate in biosynthesis of arginine and its significance in production of ruminant animals

Arginine (ARG) exerts many beneficial effects on animal body and enhanced angiogenesis, lactogenesis, which finally leads to the improvement in nitrogen (N) metabolism, reproduction, lactation, immunity and growth. Unfortunately, unprotected ARG will be degraded in the rumen and its price is high, thus feeding rumen-protected ARG seems to be uneconomical. Alternatively, N-carbamoyl glutamate (NCG) is structural analogue of N-acetyl glutamate, cofactor of cabamoyl phosphate synthetase1, is lower in rumen degradation compared to ARG. Additionally, rumen epithelial and duodenal cells have potentially utilized the NCG for ureagenesis. Supplementation of NCG to high yielding dairy cows increased plasma concentration of ARG and nitric oxide, decreased the plasma ammonia N and improved lactation performance and N utilization. Supplementation of NCG enhanced pregnancy rates in rats, improved litter size and fetal survival rate, thereby improved the reproductive performance of sows. Oral NCG supplementation increases plasma ARG and somatotropin levels, and increased growth rate and muscle protein synthesis in nursing piglets. The NCG is potential a relatively cheaper source of feed additive to offer vital compensation over oral administration of ARG, resulting in improved ruminant animal health and production. In this article, we reviewed the mechanism of ARG biosynthesis by NCG and their significance in growth, reproduction, milk production and N utilization in ruminant animals.

The consequences of metabolic changes in high-yielding dairy cows on oocyte and embryo quality

Unsatisfactory reproductive performance in dairy cows, such as reduced conception rates, in addition to an increased incidence of early embryonic mortality, is reported worldwide and has been associated with a period of negative energy balance (NEB) early post partum. Typically, NEB is associated with biochemical changes such as high non-esterified fatty acid (NEFA), high β-hydroxybutyrate (β-OHB) and low glucose concentrations. The concentrations of these and other metabolites in the follicular fluid (FF) of high-yielding dairy cows during NEB were determined and extensively analyzed, and then were replicated in in vitro maturation models to investigate their effect on oocyte quality. The results showed that typical metabolic changes during NEB are well reflected in the FF of the dominant follicle. However, the oocyte seems to be relatively isolated from extremely elevated NEFA or very low glucose concentrations in the blood. Nevertheless, the in vitro maturation models revealed that NEB-associated high NEFA and low glucose levels in the FF are indeed toxic to the oocyte, resulting in deficient oocyte maturation and developmental competence. Induced apoptosis and necrosis in the cumulus cells was particularly obvious. Furthermore, maturation in saturated free fatty acid-rich media had a carry-over effect on embryo quality, leading to reduced cryotolerance of day 7 embryos. Only β-OHB showed an additive toxic effect in moderately hypoglycemic maturation conditions. These in vitro maturation models, based on in vivo observations, suggest that a period of NEB may hamper the fertility of high-yielding dairy cows through increased NEFA and decreased glucose concentrations in the FF directly affecting oocyte quality. In addition to oocyte quality, these results also demonstrate that embryo quality is reduced following an NEB episode. This important observation may be linked to the typical diet provided to stimulate milk yield, or to physiological adaptations sustaining the high milk production. Research into this phenomenon is ongoing.

Efeito do nível nutricional antes e após a ovulação sobre a taxa de gestação e a prolificidade em ovelhas Santa Inês

Quarenta e três ovelhas foram distribuídas em quatro tratamentos em um delineamento de blocos casualizados. Os tratamentos consistiram no fornecimento de dietas de flushing, formuladas com farelo de soja (FFS) ou com glúten de milho e farelo de algodão (FGM+FA) por 28 dias antes da ovulação, seguido pelo fornecimento de dietas de flushing ou de uma dieta de mantença (DM) durante 28 dias após a ovulação: T1 - FFS antes e após a ovulação (n=12); T2 - FFS antes da ovulação e DM após (n=11); T3 - FGM+FA antes e após a ovulação (n=10); T4 - FGM+FA antes da ovulação e DM após (n=10). O ganho de peso e o peso final não diferiram (P>0,05) entre os animais dos tratamentos. O ECC final foi maior (P<0,05) nas ovelhas do tratamento T3 do que nas do tratamento T2. A concentração de N-ureico foi maior (P<0,05) nas ovelhas dos tratamentos T1 e T3 do que naquelas dos tratamentos T2 e T4. A taxa de gestação e a prolificidade não diferiram (P>0,05) entre os animais. As dietas de flushing antes da ovulação, seguidas pelo fornecimento destas mesmas dietas ou de uma dieta de mantença após a ovulação, não alteraram a taxa de gestação e a prolificidade.

Plasma urea nitrogen in relation to pregnancy rate in dairy sheep

The aim of this field study was to investigate the relationship of plasma urea nitrogen (PUN) with the pregnancy rate in lactating Awassi × Merino ewes. One hundred and eighty-five Awassi × Merino ewes were used in the present study. Ewes were fed a diet containing 17.4% crude protein and were milked twice a day by the milking machine. The ewes were synchronized for estrus by insertion of intravaginal sponges containing 30 mg flurogestone acetate for 14 days. At the time of sponge removal each ewe was administered eCG (600 IU). All ewes were inseminated twice with fresh semen into the external os of the cervix at 48 and 56 h after sponge removal. The day of insemination was considered as Day 0 for calculating the gestational period. Blood samples were collected from each ewe at Days 0, 18 for measurement of PUN concentrations and at Day 22 after AI for measurement of pregnancy-associated glycoprotein (PAG) by radioimmunoassay (RIA). Thirty-eight ewes (20.5%) were confirmed pregnant by PAG-RIA test at Day 22 and by ultrasonography at Day 80. The mean (±S.D.) concentration of PUN in all ewes at Day 0 was 12.7±4.6 mmol/L. There were non-significant differences in the level of PUN between pregnant and non-pregnant ewes at Days 0 (12.2±4.2 mmol/L vs. 12.8±4.7 mmol/L, respectively) and 18 (9.6±2.9 mmol/L vs. 10.4±4.0 mmol/L, respectively) after AI. Mean PUN concentrations decreased significantly from Day 0 to Day 18 after AI in both pregnant and non-pregnant ewes. By using logistic regression analysis, there was no effect of PUN concentrations on the probability of pregnancy occurrence in the studied ewes (odds ratio: 0.97; 95% confidence interval: 0.9-1.05; P=0.45). In conclusion, there was no evidence of a relationship between PUN concentration and pregnancy rate for lactating Awassi × Merino ewes in the present study because of low pregnancy rate observed.

The influence of genetic selection and feed system on the reproductive performance of spring-calving dairy cows within future pasture-based production systems

Three genetic groups of Holstein-Friesian dairy cows were established from within the Moorepark (Teagasc, Ireland) dairy research herd: LowNA, indicative of the Irish national average-genetic-merit North American Holstein-Friesian; HighNA, high-genetic-merit North American Holstein-Friesian; HighNZ, high-genetic-merit New Zealand Holstein-Friesian. Genetic merit in this study was based on the Irish total merit index, the Economic Breeding Index. Animals from within each genetic group were randomly allocated to 1 of 2 possible post-European Union-milk-quota pasture-based feeding systems (FS): 1) The Moorepark (MP) pasture system (2.64 cows/ha and 500 kg of concentrate supplement per cow per lactation) and 2) a high output per hectare (HC) pasture system (2.85 cows/ha and 1,200 kg of concentrate supplement per cow per lactation). A total of 126, 128, and 140 spring-calving dairy cows were used during the years 2006, 2007, and 2008, respectively. Each group had an individual farmlet of 17 paddocks, and all groups were managed similarly throughout the study. The effects of genetic group, FS, and the interaction between genetic group and FS on reproductive performance, body weight, body condition score, and blood metabolite concentrations were studied using mixed models with factorial arrangements of genetic groups and FS. Odds ratios were used in the analysis of binary fertility traits, and survival analysis was used in the analysis of survival after first calving. When treatment means were compared, the HighNA and HighNZ genotypes (with greater genetic merit for fertility performance) had greater first-service pregnancy rates and had a greater proportion of cows pregnant after 42 d of the breeding season than the LowNA group. Both HighNA and HighNZ genotypes were submitted for artificial insemination earlier in the breeding season and had greater survival than the LowNA genotype. There was no significant FS or genotype by FS interactions for any of the reproductive, blood metabolite, body weight, or body condition score measures. The results demonstrate that increased genetic merit for fertility traits resulted in improved reproductive performance and that the poor reproductive capacity of inferior-genetic-merit animals for fertility was not improved through concentrate supplementation at pasture.

Effects of plasma urea nitrogen levels on the bovine oocyte ability to develop after in vitro fertilization

The overall aim of the present study was to evaluate in vitro development ability of oocytes recovered from 56 Holstein Frisian heifers with low [group 1 (G1): <13 mg /dl], moderate [group 2 (G2): 13-16 mg /dl] and high [group 3 (G3): >16 mg /dl] plasma urea nitrogen (PUN) concentrations, to determine whether PUN concentrations affect the competence of oocytes to progress to blastocysts after in vitro fertilization. In vitro oocyte and embryo development was assessed by blastocyst rates, embryo total cell numbers and apoptosis. Blood samples for the determination of PUN were collected 24 h prior to collection of the ovaries at the slaughter. A total of 112 ovaries were collected at a local abattoir and oocytes (n = 697) were aspirated, in vitro matured and fertilized. On day 8, blastocysts were assigned to the terminal dUTP nick end labelling assay. Cleavage rates were significantly higher (p < 0.001) for groups 1 and 2 than for group 3 (i.e. 72.5% and 72.2% vs 61.7%, respectively). The proportion of fertilized oocytes that developed into blastocysts was higher (p < 0.05) for group 1 than for group 3 (34.0% vs 23.0%, respectively). Day 8 blastocysts showed higher total cell counts (p < 0.05) for group 1 than for group 3 (123.7 vs 76.3), and a higher (p < 0.05) total apoptotic cell rate was found in group 3 (25.9 and 19.0 vs 43.2 for G1, G2 and G3, respectively). In conclusion, the ability of oocytes from heifers with increased levels of PUN to develop to the blastocyst stage was significantly reduced when standard routines for in vitro maturation, fertilization and culture were followed. These detrimental effects can be mediated in part through direct effect of urea and/or by the metabolic products on the process of follicle-enclosed oocyte nuclear and cytoplasmic development.

Toward a Feline-Optimized Culture Medium: Impact of Ions, Carbohydrates, Essential Amino Acids, Vitamins, and Serum on Development and Metabolism of In Vitro Fertilization-Derived Feline Embryos Relative to Embryos Grown In Vivo1

The objective of this study was to define the physiologic needs of domestic cat embryos to facilitate development of a feline-specific culture medium. In a series of factorial experiments, in vivo-matured oocytes (n = 2040) from gonadotropin-treated domestic cats were inseminated in vitro to generate embryos (n = 1464) for culture. In the initial study, concentrations of NaCl (100.0 vs. 120.0 mM), KCl (4.0 vs. 8.0 mM), KH(2)PO(4) (0.25 vs. 1.0 mM), and the ratio of CaCl(2) to MgSO(4)-7H(2)O (1.0:2.0 mM vs. 2.0:1.0 mM) in the medium were evaluated during Days 1-6 (Day 0: oocyte recovery and in vitro fertilization [IVF]) of culture. Subsequent experiments assessed the effects of varying concentrations of carbohydrate (glucose, 1.5, 3.0, or 6.0 mM; l-lactate, 3.0, 6.0, or 12.0 mM; and pyruvate, 0.1 or 1.0 mM) and essential amino acids (EAAs; 0, 0.5, or 1.0x) in the medium during Days 1-3 and Days 3-6 of culture. Inclusion of vitamins (0 vs. 1.0x) and fetal calf serum (FCS; 0 vs. 5% [v/v]) in the medium also was evaluated during Days 3-6. Development and metabolism of IVF embryos on Day 3 or Day 6 were compared to age-matched in vivo embryos recovered from naturally mated queens. A feline-optimized culture medium (FOCM) was formulated based on these results (100.0 mM NaCl, 8.0 mM KCl, 1.0 mM KH(2)PO(4), 2.0 mM CaCl(2), 1.0 mM MgSO(4), 1.5 mM glucose, 6.0 mM L-lactate, 0.1 mM pyruvate, and 0x EAAs with 25.0 mM NaHCO(3), 1.0 mM alanyl-glutamine, 0.1 mM taurine, and 1.0x nonessential amino acids) with 0.4% (w/v) BSA from Days 0-3 and 5% FCS from Days 3-6. Using this medium, ~70% of cleaved embryos developed into blastocysts with profiles of carbohydrate metabolism similar to in vivo embryos. Our results suggest that feline embryos have stage-specific responses to carbohydrates and are sensitive to EAAs but are still reliant on one or more unidentified components of FCS for optimal blastocyst development.