Cycle In Cattle Research Articles

Macrophage-specific responses to human- and animal-adaptedtubercle bacilli reveal pathogen and host factors drivingmultinucleated cell formation.

The Mycobacterium tuberculosis complex (MTBC) is a group of related pathogens that cause tuberculosis (TB) in mammals. MTBC species are distinguished by their ability to sustain in distinct host populations. While Mycobacterium bovis (Mbv) sustains transmission cycles in cattle and wild animals and causes zoonotic TB, M. tuberculosis (Mtb) affects human populations and seldom causes disease in cattle. The host and pathogen determinants underlying host tropism between MTBC species are still unknown. Macrophages are the main host cell that encounters mycobacteria upon initial infection, and we hypothesised that early interactions between the macrophage and mycobacteria influence species-specific disease outcome. To identify factors that contribute to host tropism, we analysed blood-derived primary human and bovine macrophages (hMϕ or bMϕ, respectively) infected with Mbv and Mtb. We show that Mbv and Mtb reside in different cellular compartments and differentially replicate in hMϕ whereas both Mbv and Mtb efficiently replicate in bMϕ. Specifically, we show that out of the four infection combinations, only the infection of bMϕ with Mbv promoted the formation of multinucleated giant cells (MNGCs), a hallmark of tuberculous granulomas. Mechanistically, we demonstrate that both MPB70 from Mbv and extracellular vesicles released by Mbv-infected bMϕ promote macrophage multinucleation. Importantly, we extended our in vitro studies to show that granulomas from Mbv-infected but not Mtb-infected cattle contained higher numbers of MNGCs. Our findings implicate MNGC formation in the contrasting pathology between Mtb and Mbv for the bovine host and identify MPB70 from Mbv and extracellular vesicles from bMϕ as mediators of this process.

Reconstructing dynamics of foodborne disease outbreaks in the US cattle market from monitoring data.

Conventional empirical studies of foodborne-disease outbreaks (FDOs) in agricultural markets are linear-stochastic formulations hardwiring a world in which markets self-correct in response to external random shocks including FDOs. These formulations were unequipped to establish whether FDOs cause market reaction, or whether markets endogenously propagate outbreaks. We applied nonlinear time series analysis (NLTS) to reconstruct annual dynamics of FDOs in US cattle markets from CDC outbreak data, live cattle futures market prices, and USDA cattle inventories from 1967–2018, and used reconstructed dynamics to detect causality. Reconstructed deterministic nonlinear market dynamics are endogenously unstable—not self-correcting, and cattle inventories drive futures prices and FDOs attributed to beef in temporal patterns linked to a multi-decadal cattle cycle undetected in daily/weekly price movements investigated previously. Benchmarking real-world dynamics with NLTS offers more informative and credible empirical modeling at the convergence of natural and economic sciences.

Targeting the Hindgut to Improve Health and Performance in Cattle.

Simple SummaryIt is well established that the functions of the gastrointestinal tract go beyond the digestion and absorption of nutrients. For instance, its constant contact with the gastrointestinal microbes and components of the diet makes it a major player within the immune system. Preserving the gut’s barrier function is essential to maintaining overall health and subsequently performance in farm animals. In cattle, multiple factors throughout their productive cycle can have negative consequences on gut health, including dietary changes. Most research in this topic has focused on rumen health, due to its critical role in digestion in bovines. However, it is increasingly evident that other sections of the gastrointestinal tract, such as the large intestine (also referred to as the hindgut), are similarly impacted by the same factors. Nutritional strategies aimed to promote rumen health have proven beneficial for overall health and performance in bovines. Targeting the hindgut might represent a window of opportunity for further improvement.An adequate gastrointestinal barrier function is essential to preserve animal health and well-being. Suboptimal gut health results in the translocation of contents from the gastrointestinal lumen across the epithelium, inducing local and systemic inflammatory responses. Inflammation is characterized by high energetic and nutrient requirements, which diverts resources away from production. Further, barrier function defects and inflammation have been both associated with several metabolic diseases in dairy cattle and liver abscesses in feedlots. The gastrointestinal tract is sensitive to several factors intrinsic to the productive cycles of dairy and beef cattle. Among them, high grain diets, commonly fed to support lactation and growth, are potentially detrimental for rumen health due to their increased fermentability, representing the main risk factor for the development of acidosis. Furthermore, the increase in dietary starch associated with such rations frequently results in an increase in the bypass fraction reaching distal sections of the intestine. The effects of high grain diets in the hindgut are comparable to those in the rumen and, thus, hindgut acidosis likely plays a role in grain overload syndrome. However, the relative contribution of the hindgut to this syndrome remains unknown. Nutritional strategies designed to support hindgut health might represent an opportunity to sustain health and performance in bovines.

Cycles in cattle and hog prices in South America

Prices of agricultural products often vary in relatively stable patterns around their long‐run trends. These variations translate into fluctuations of selling prices as well as farm revenues. We provide an overview of the current literature on agricultural price cycles. Using a transparent and reproducible model selection process and the Kalman filter, we select optimal models and estimate the cyclic patterns of hog and cattle prices for Brazil, Chile and Uruguay. Durations of those cycles are found to be about three years and seven years, respectively. These durations are in line with the literature and the biological characteristics of livestock production. Our results can inform producers forecasts on price developments in the short and medium run. They are useful for guiding policy makers on the timing of policy interventions for influencing the duration or the amplitudes of cycles.

ДИНАМИКА ПРОГЕСТЕРОНА И ГОНАДОТРОПИНОВ В КРОВИ ТЕЛОК ПРИ СИНХРОНИЗАЦИИ ПОЛОВОЙ ОХОТЫ С ИСПОЛЬЗОВАНИЕМ УДЧ ДИОКСИДА КРЕМНИЯ

The paper presents the results of studying the possibility of controlling the links of hormonal regulation of the reproductive cycle of cattle using silicon dioxide in an ultra-dispersed form to increase fertilization during frontal insemination. The aim of the study was to analyze the effect of silicon dioxide UDPs when used in the scheme for synchronizing the sexual cycle of heifers on the dynamics of progesterone, FSH and LH and the fertilization of animals from frontal insemination. The studies were carried out on breeding age heifers of the red steppe breed. We formed two groups by 10 heifers – the control and the experimental one. In both groups, the synchronization of estrus was carried out by double application of estrophan. In the experimental group, the animals were simultaneously injected with estrophan with a solution of silicon dioxide ultra-dispersed particles in isotonic sodium chloride solution (dose of silicon dioxide 10 μg/kg). Blood for the determination of hormones was taken from heifers on the 1st, the 11th and 14th days of the experiment. All animals were inseminated frontally with deep-frozen semen by the rectocervical method. It was found that in the experimental and control groups, the dynamics of gonadotropins during the induced sexual cycle was similar; however, the LH level before insemination in heifers of the experimental group exceeded that in the control by 0.81 ng/ml (34.4%). Fertility of heifers in the experimental group was 70.0%, in the control – 50.0%. The effect of silicon dioxide in the UDP form on the dynamics of sex hormones and the fertility of heifers from frontal insemination during estrus synchronization was studied for the first time.

Tissue preparations as an eff ective means of correction of sexual cyclicalityof infertile cows in the conditions of forest-steppe zone in Zhytomyr region

Implementation of the latest technologies of animal reproduction causes changes in the life of their body and infl uences the manifestation of sexual cyclicity. As a result, one of the main tasks of specialists of veterinary medicine is the elimination of infertility of cows and heifers and improvement of methods of regulation of their reproductive functions. In recent years, in veterinary medicine for prophylactic and therapeutic purposes individually or in combination with other agents during pregnancy, in the postpartum period for gynecological diseases, to stimulate the functions of the sexual apparatus of animals, and their farming to improve productivity eff ectively used biogenic stimulators, that are made of tissues and organs of animals and plants – tissue preparations. But remain changes of the sexual apparatus of infertile cows are not studied in their use. Therefore, the purpose of the research was to study the eff ect of tissue preparations in a complex with ihglukovit for the correction of the sexual cycle of the infertile cows in the conditions of forest-steppe in Zhytomyr region. It has been found that the using tissue preparations make from the liver and placenta and ihglukovit for cows, time successful insemination was minimal and was 47.0±5.11 days. We also observed a positive eff ect on the usefulness of the fl ow of the sexual cycle when used in complex tissue preparations from the liver and placenta, as a consequence of infertility in the cow was of 17.00±1.14 days. As all experienced animals received ihglukovit, and the period of occurrence of complete sexual cycle and the eff ectiveness of insemination of cows was diff erent, then we assume that the changes in animals are due primarily to the infl uence of tissue preparations. We believe that the using of "placental" tissue preparation make from the uterus of pregnant cows with contents was the most eff ective, because it includes biologically active substances that are similar to the sexual apparatus of a cow. Analyzing the obtained results, we recommend to apply the tissue preparation liver, placenta and ihglukovit at a dose of 20 cm3 per animal, three times with an interval of 8-10 days to correct the sexual cycle of cattle and prevention of infertility. Key words: biogenic stimulant, tissue preparation, ihglukovit, reproduction, sexual cycle, infertility, cows.

Assessing Transparency, Accuracy, and Consistency of Relative Importance of Cow-Calf Profitability Drivers Using Neural Networks versus Regression

AbstractUsing both multivariate regression and artificial neural networks, the relative impact of variables affecting cow-calf profitability was examined over two cattle cycles for spring- and fall-calving herds that varied in size by time period analyzed when using different fertility management affecting forage yields with and without weather uncertainty. Neural networks had greater predictive accuracy than regression but at the cost of lesser transparency and predictive consistency. Explaining profitability, price, and quantity of cattle sold were consistently and respectively ranked first and second using both approaches. Importance rankings for hay sold and fertilizer were low and less consistent across techniques employed.

Development of animal collar for state of health determination of livestock

The variation of Livestock physiological parameters such as stress level, rumination, body temperature has harmful effect in reproduction cycle and also causes diseases such as Mastitis, Milk fever, Lameness etc. Development of animal collar for monitoring the physiological parameters may help in better management of cattle diseases and reproduction cycle. The advantages of this system include simplicity, portability and inexpensive health care of livestock. The cattle surface body temperature was measured continuously for one day with an interval of one hour. The body temperature of the cattle measured using DHT11 sensor and mercury thermometer is compared and the average difference between the temperature measured using DHT11 sensor and mercury thermometer is 0.03°C indicating the feasibility of this method to monitor state of health of a cattle. With the temperature data and humidity data obtained from DHT11 sensor THI index is calculated and stress level of the cattle is predicted without using any sensor. The ADXL335 sensor is fixed under the collar near the left side of the mouth of the livestock to monitor rumination of cattle. This system is implemented in the Rangampet village, Chittoor district in Andhra Pradesh. The prototype of the collar based cattle health monitoring system shows that it is helpful for livestock farmers for recognizing various diseases accurately.

Nutritive value of improved populations Brachiaria ruziziensis

A low number of Brachiaria ruziziensis (Syn. Urochloa) cultivars available on the market and a lack of information about its forage potential have made it difficult to expand its cultivated area, and have therefore made it necessary to implement a breeding program for this species. Thus, the objective of this work was to evaluate the nutritional value of ten improved populations of Brachiaria ruziziensis (Syn. Urochloa) and two controls (B. ruziziensis cv. Kennedy and B. brizantha cv. Marandu). The experimental design was a randomized block design with three replications in five sections. The data were submitted to analysis of variance in the subdivided plot in which the primary factors were the populations and the secondary cuts. The Tukey test was used at 5% of significance for the comparison of means. The genotypes used came from the third recurrent selection cycle of Embrapa dairy cattle, originating from the interbreeding of clones which had been identified as superior. The height of the cuts was 10 cm in relation to the ground. The material was cut and weighed in the field to obtain the sample weights to determine the nutritional forage value. After drying, the samples were ground in 1 mm sieves for chemical analyzes and in vitro digestibility. The best CP, ADF and NDF levels observed in IV populations (lower levels of ADF and NDF at 93 days of cut interval and lower NDF contents at 35 and 41 days of cut interval), population VI (higher CP content in the interval of 93 days, lower DM content at 64 and 93 days of cut interval, and lower NDF content at 35 and 64 days of cut interval) showed that these populations can be evaluated under grazing even at an advanced maturation stage. The objective of these selections was to evaluate the nutritional value of improved populations of Brachiaria ruziziensis (Syn. Urochloa) in order to obtain more homogeneous populations for implantation of grazing experiments.

Nutritive value of improved populations Brachiaria ruziziensis

A low number of Brachiaria ruziziensis (Syn. Urochloa) cultivars available on the market and a lack of information about its forage potential have made it difficult to expand its cultivated area, and have therefore made it necessary to implement a breeding program for this species. Thus, the objective of this work was to evaluate the nutritional value of ten improved populations of Brachiaria ruziziensis (Syn. Urochloa) and two controls (B. ruziziensis cv. Kennedy and B. brizantha cv. Marandu). The experimental design was a randomized block design with three replications in five sections. The data were submitted to analysis of variance in the subdivided plot in which the primary factors were the populations and the secondary cuts. The Tukey test was used at 5% of significance for the comparison of means. The genotypes used came from the third recurrent selection cycle of Embrapa dairy cattle, originating from the interbreeding of clones which had been identified as superior. The height of the cuts was 10 cm in relation to the ground. The material was cut and weighed in the field to obtain the sample weights to determine the nutritional forage value. After drying, the samples were ground in 1 mm sieves for chemical analyzes and in vitro digestibility. The best CP, ADF and NDF levels observed in IV populations (lower levels of ADF and NDF at 93 days of cut interval and lower NDF contents at 35 and 41 days of cut interval), population VI (higher CP content in the interval of 93 days, lower DM content at 64 and 93 days of cut interval, and lower NDF content at 35 and 64 days of cut interval) showed that these populations can be evaluated under grazing even at an advanced maturation stage. The objective of these selections was to evaluate the nutritional value of improved populations of Brachiaria ruziziensis (Syn. Urochloa) in order to obtain more homogeneous populations for implantation of grazing experiments.

Doppler sonography of the corpus luteum during the oestrus cycle in dairy cows

Doppler ultrasound has recently emerged as one of the main innovations in cattle practice and has mainly found application in the evaluation of luteal blood perfusion (LBF). LBF has been evaluated during different phases of the oestrous cycle, but the technique is poorly standardized. The aim of the study was to evaluate visual and quantitative changes of size of corpus luteum (CL) and LBF in dairy cattle during an oestrous cycle at 2 follicular waves using colour flow mode (CFM) and power flow mode (PFM) doppler ultrasound. Ten Friesian cows were selected and synchronized. The CL was evaluated at 3/4-day intervals until the next oestrus onset. After identifying the spiral luteal artery entry at the base of the CL, multiple scans of the vertical plane at the maximum diameter of the CL from the apex to the base were recorded in B-mode, CFM and PFM for each cow and session. An Esaote Mylab vet 30 gold was employed with the following setting: pulse repetition frequency 2.1 (CFM) or 2.8 (PFM), gain 70%. The real area of CL (RACL) was calculated subtracting the area of the eventual inner cavity. The LBF was quantified off-line by means of a visual score and of an image analysis system (Digimizer 4.1). Student and Anova tests were used for statistical analysis. Data were presented as means and standard deviations. There were significant individual variations for the RACL and LBF when calculated in CFM. PFM minimized these variations, although, at day 15-16, it was also affected by individual factors (p < 0.01). The combined study of RACL and LBF during a 2-wave oestrous cycle distinguished 3 phases: a phase of CL formation (3-4 days) with LBF of 0.3 ± 0.3 cm2 on a RACL of 3.1 ± 0.9 cm2, a central phase (7-16 days) with LBF of 0.7 ± 0.4 cm2 on a RACL of 4.8 ± 0.8 cm2 and a regression phase (19-20 days) with a minimum LBF of 0.1 ± 0.1 cm2 in a CL of 3.3 ± 0.6 cm2. According to this study, there is no significant difference of LBF from 7 to 16 days of the oestrus cycle; although the RACL significantly changes in this period, the dimensional variations are too thin to be clinically appreciated. However, this study contributed to defining the values of RACL and LBF during a 2-wave oestrous cycle of dairy cattle.

Metabolomic Profile of Oviductal Extracellular Vesicles across the Estrous Cycle in Cattle

Oviductal extracellular vesicles (oEVs) have been proposed as key modulators of gamete/embryo maternal interactions. The aim of this study was to examine the metabolite content of oEVs and its regulation across the estrous cycle in cattle. Oviductal EVs were isolated from bovine oviducts ipsilateral and contralateral to ovulation at four stages of the estrous cycle (post-ovulatory stage, early and late luteal phases, and pre-ovulatory stage). The metabolomic profiling of EVs was performed by proton nuclear magnetic resonance spectroscopy (NMR). NMR identified 22 metabolites in oEVs, among which 15 were quantified. Lactate, myoinositol, and glycine were the most abundant metabolites throughout the estrous cycle. The side relative to ovulation had no effect on the oEVs’ metabolite concentrations. However, levels of glucose-1-phosphate and maltose were greatly affected by the cycle stage, showing up to 100-fold higher levels at the luteal phase than at the peri-ovulatory phases. In contrast, levels of methionine were significantly higher at peri-ovulatory phases than at the late-luteal phase. Quantitative enrichment analyses of oEV-metabolites across the cycle evidenced several significantly regulated metabolic pathways related to sucrose, glucose, and lactose metabolism. This study provides the first metabolomic characterization of oEVs, increasing our understanding of the potential role of oEVs in promoting fertilization and early embryo development.

Characterization of Fecal Shiga Toxin-Producing Escherichia coli from Post-Weaning Cattle

ObjectivesShiga toxin-producing E. coli (STEC), which are often found in the intestinal tract of cattle and in their fecal matter, are among the most common foodborne pathogens of concern in beef production. Contamination from the fecal matter, both directly and indirectly, during harvest may compromise the safety of the beef products, which can have devastating impact on consumers and producers alike. While the microbial load present in cattle fecal matter may change as the cow matures, previous research has generally focused on analysis of the pathogen load late in the life cycle of cattle. There is merit in the analysis of this load earlier in the life cycle of cattle, as this may serve to subsequently control the pathogen load during later stages of production. As such, this study aims to assess the prevalence and characteristics of STEC in beef cattle production at the early post-weaning stage.Materials and MethodsRectal fecal samples from post-weaning cattle (n = 68) were collected. Ten grams of each sample was mixed and manually homogenized with 90mL tryptic soy broth (TSB) with added phosphates. The homogenized samples were spread-plated on CHROMagar STEC plates and incubated at 35°C for 24h before enumeration. To determine STEC prevalence, the homogenized samples were incubated at 42°C for 6 h, and streaked onto a second set of CHROMagar STEC plates, which were incubated at 35°C for 24h. Colonies with a purple coloration were STEC-positive. Two random STEC-presumptive colonies from each sample were tested via subsequent PCR amplification and gel electrophoresis to confirm the presence of stx1, stx2, and/or eae genes.Acid-resistant strains of presumptive STEC colonies from the enriched samples were collected and inoculated into TSB for recovery. One hundred microliters of the inoculated sample were then transferred into TSB without dextrose and incubated at 35°C for 24h, and finally challenged in acidified TSB without dextrose (pH = 3.50) for 1h and 6h. One hundred microliters of each survival sample were plated onto tryptic soy agar (TSA), and incubated at 35°C for 48h.ResultsThe fecal samples had an average 4.79 ± 1.24 log CFU/g (ranging 2.30 to 6.83) of STEC colonies. All samples were STEC-positive, as all samples had at least one of the three genes tested for (stx1, stx2, eae). All sixty-eight samples were confirmed positive for gene stx1, 12% (8 of 68) samples were confirmed positive for stx2, 62% (42 of 68) of samples were confirmed positive for eae, and 12% (8 of 68) were positive for all three genes. Of 67 samples tested for acid resistance, 34% (23 of 67) survived after 6 h in acidified growth media (pH = 3.50).ConclusionThis study provided preliminary data on the pathogen load of early post-weaning cattle. The prevalence of acid resistance shown may be a possible cause of concern, as these surviving bacteria can survive high acidic conditions. This may expedite the spread of acid-resistant pathogens within the food supply chain as acidic antimicrobial chemicals become ineffective in reducing pathogen populations. These results may be used as a baseline for future research regarding STEC prevalence or acid resistance aimed at reducing pathogen load in beef cattle production. Given the prevalence of acid resistance, further development is recommended for non-acid post-harvest antimicrobial interventions to reduce the presence of acid resistant STEC.

Profile of bile acid subspecies is similar in blood and follicular fluid of cattle.

The composition of follicular fluid (FF) has an impact on the developmental capacity of the oocyte and the resulting embryo. FF is composed of blood plasma constituents which cross the blood follicular barrier and the secretory components of granulosa and theca cells. Moreover, it has been shown recently that follicular cells have the ability to synthesize bile acids (BAs). BAs are present in several fluids of mammals especially in bile, blood and urine. FF is an essential impacting factor on the oocyte quality and therefore resulting embryos. To achieve a better understanding of this subject, the presence and concentration of BAs were measured in fluid collected from bovine follicles, categorized according to their size, throughout two entire oestrus cycles and compared to those in blood and urine. The body fluids were collected during the same examination procedure and in total samples from four heifers were obtained. A broad spectrum of 11 BA derivatives was measured applying liquid chromatography–tandem mass spectrometry (LC‐MS/MS). The simultaneous and direct quantification of BAs in different body fluids of cattle are reported. Within the follicular fluid, blood and urine, cholic acid and glycocholic acid are the dominant BA subspecies irrespective of the oestrus cycle stage. Moreover, BA concentrations in blood compared to those in the FF were similar. For the first time these results clearly highlight the presence of different BA subspecies in FF, blood and urine during the oestrus cycle in cattle.

Progestogen profiling in plasma during the estrous cycle in cattle using an LC-MS based approach

In many mammalian species, corpus luteum derived progesterone (P4) is the main functional gestagen during the estrous cycle and pregnancy. P4 can be metabolized into various metabolites, of which some are biologically active. While some metabolites target the classical nuclear progesterone receptor (PR), neurosteroids bind the receptors of type A γ-aminobutyric acid (GABAA-r) in the brain. According to the position of reduction within the molecule, metabolites of P4 can be characterized into C20-reduced progestogens (20α-dihydroprogesterone (20α-DHP) and 20β-dihydroprogesterone (20β-DHP)), C3-reduced progestogens (3α-dihydroprogesterone (3α-DHP) and 3β-dihydroprogesterone (3β-DHP)), 5α-reduced progestogens (5α-dihydroprogesterone (5α-DHP), allopregnanolone and isopregnanolone) and 5β-reduced progestogens (5β-dihydroprogesterone (5β-DHP), pregnanolone and epipregnanolone). We questioned whether the reduced progestogens are present in bovine plasma during the estrous cycle and whether their profiles differed from the profile of the common precursor P4 around the time of luteolysis. The analytes were monitored in plasma samples using liquid chromatography mass spectrometry (LC-MS). While progestogens lagged behind the drop of P4 at luteolysis, they followed the profile of P4 during the estrous cycle. The abundance of P4 was predominant followed by allopregnanolone, pregnanolone, epipregnanolone and 20β-DHP. Further studies will need to focus particularly on the period around luteolysis.

Stage-dependent changes in oviductal phospholipid profiles throughout the estrous cycle in cattle

Sperm capacitation, fertilization and embryo development take place in the oviduct during the periovulatory period of the estrous cycle. Phospholipids are crucial metabolites for sperm capacitation and early embryo development. The aim of this study was to monitor the abundance of phospholipids in the bovine oviductal fluid (OF) according to the stage of the estrous cycle and the side relative to ovulation. Pairs of bovine oviducts were collected in a slaughterhouse and classified into four stages of the estrous cycle: post-ovulatory (Post-ov), mid-luteal (Mid-lut), late-luteal (Late-lut) and pre-ovulatory (Pre-ov) phases (n = 17 cows/stage). Cell-free OF from oviducts ipsilateral and contralateral to the site of ovulation were analyzed using MALDI-TOF mass spectrometry. Lipid identification was achieved by high resolution mass spectrometry. A total of 274 lipid masses were detected in the mass range of 400–1000 Da, corresponding mostly to phosphatidylcholines (PC), lysoPC, phosphatidylethanolamine (PE), lysoPE and sphingomyelins (SM). Ipsilateral and contralateral OF did not differ in their lipid profiles at any stage of the cycle. However, 127 and 96 masses were differentially abundant between stages in ipsilateral and contralateral OF, respectively. Highest differences in lipid profiles were observed in the Pre-ov vs. Mid-lut and Pre-ov vs. Late-lut comparisons in both sides relative to ovulation. Differential abundance of specific molecules of PC, PE, SM and l-carnitine were observed at Pre-ov and Post-ov compared with the luteal phase. This work proposes new candidates potentially able to regulate sperm capacitation and early embryo development.

Sensory and behavioural control of gonadotrophin secretion during suckling-mediated anovulation in cows

A major limiting factor in the resumption of postpartum ovarian cycles in cattle is the inhibitory influence of the suckling calf on central regulatory elements controlling the release of GnRH from the median eminence. This inhibitory influence occurs only as a consequence of specifically defined behavioural interactions between the cow and calf in the presence of a maternal bond, cannot be simulated experimentally using thermal, electrical or mechanical stimuli, and is not dependent upon sensory ennervation within the udder. Indeed, the identity of the calf, either own or unrelated, appears to define the neuroendocrine events that attend the maintenance of the anovulatory state under controlled experimental conditions. Hence, new hypotheses that focus upon the relationship between physiological correlates of maternal behaviour and hypothalamic regulation of LH secretion are currently being tested. Specific aspects of these relationships remain conjectural, but are postulated to include the regulation of opioid tone, intracerebral oxytocin, and modulation of synthetic or excitatory activity of GnRH secretory neurones. Defining the role of the special senses in transduction of signals from calves that influence these neuronal processes may provide insight for developing practical intervention strategies of the future.

Training on Heat Detection to Increase the Success Rate of Cattle Artificial Insemination for Girinka Beneficiaries in Huye District, Rwanda

Cattle farming is important for the socio-economic development of Rwanda, representing 12% of the national gross domestic product (GDP). In general, livestock production is a primary source of income. Recognizing the importance of cattle, the Government of Rwanda introduced the Girinka program in 2006 to reduce poverty and childhood malnutrition by providing poor people with dairy cows. The sustainability of the Girinka program relies on the successful breeding of cattle. Artificial Insemination (AI) is a method that can enhance cattle reproduction, but many Girinka beneficiaries did not have the requisite knowledge to maximize the success rate of AI by tracking the estrus cycle (heat detection) of their cattle.This project aimed to study the effect of training Girinka farmers on heat detection using the International Livestock Research Institute (ILRI) materials on cattle AI. A two-day training was provided to 74 Girinka cattle farmers. The cattle AI success rate and the farmers’ knowledge of heat detection were measured.The overall knowledge of farmers on cattle estrus cycle significantly increased from 37.16% pre-intervention to 92.34% post-intervention (P=0.008). The AI success rate significantly increased from 44% pre-intervention to 58.7% post-intervention (P<0.001).The study showed that by providing an evidence-based training to farmers on heat detection and estrus cycle in cattle could increase the success rate of AI. The same training is recommended for all Girinka beneficiaries in Rwanda. Longer term follow-up and scaling-up of the project should be considered to maximize the benefits.

The profile and percentage of vaginal epithelial cell numbers during the estrous cycle in Bali cattle

The aim of this study was to observe the percentage of the number and the diameter of vaginal epithelial cells during the estrous cycle in Bali cattle. Six female Bali cattle were used in this research. Sample collection and estrous detection were observed at 06.00-07.00 am and 17.00-18.00 pm for 28 days. The method of this research used vaginal smear with Giemsa staining and then observed by microscope. Image Raster 3.0 was used to measured cells diameter and data were analysed using Independent T-Test. Based on the results of this study, the vaginal epithelial cells during the estrous cycle were intermediate cells, parabasal cells, superficial cells, and cornification cells. The percentage of intermediate cell numbers increased in the proestrus phase and decrease in the estrous phase. The percentage of parabasal cell numbers increased in metestrus and diestrus phase along with decreased in proestrus phase and not found in the estrous phase. The percentage of superficial and cornification cell numbers increased in the estrous phase and last stage of the proestrus phase along with decreased in the metestrus phase and not found in the diestrus phase. In measuring the diameter of the vaginal epithelial cells, superficial cells have a larger cytoplasmic diameter and the smallest diameter of the cytoplasm was parabasal cells. Whereas in measuring the nucleus diameter and diameter ratio of the cytoplasmic nucleus, parabasal cells have a larger diameter and cornification cells have smallest nucleus diameter and cytoplasmic nucleus diameter ratio.

Physiological characteristics and effects on fertility of the first follicular wave dominant follicle in cattle

The first follicular wave emerges soon after ovulation, and its dominant follicle (DF) develops during the first 8–10 days of the estrous cycle in cattle. And, the first-wave DF is a non-ovulatory follicle, because it develops during the first half of the estrous cycle simultaneously with the corpus luteum (CL), which produces and secretes progesterone. Regarding the characteristics of development and the mechanisms of deviation in the DF during the follicular wave, the first-wave DF has been well studied. However, the characteristics of the first-wave DF, such as growth, blood flow in the follicular wall, concentration of sex steroid hormones in the peripheral blood and follicular fluid, amounts of mRNA in granulosa cells, as well as the characteristics of the CL formed after the first-wave DF and the influence of the first-wave DF on fertility (conception rate), have not been well studied. Additionally, the first-wave DF synthesizes and secretes 17β-estradiol (E2), and plasma E2 concentration increases during the early stage of the estrous cycle. Consequently, there is a possibility that the first-wave DF might affect the fertility in cattle. In this review, to provide the new perspective on reproductive physiology in cattle, characteristics of the first-wave DF were examined in detail and its characteristics were compared with that of the second-wave DF. In addition, the locational effects of the first-wave DF and CL on conception rate are discussed.