Cycle In Cattle Research Articles

Habitat Selection by Free-Grazing Sheep in a Mountain Pasture.

For centuries, mountain grasslands have been part of the grazing cycle of sheep and cattle in extensive management systems in the Pyrenees; however, traditional guided herding has been, in many cases, replaced by free-ranging flocks at these pastures. The goal of this study was to analyze the grazing behavior of free-ranging sheep in mountain pastures using GPS-based tracking systems and Geographic Information Systems. During the summer seasons of 2019, 2020, and 2021, a transterminant flock of free-ranging sheep was tracked with GPS devices attached to collars at the mountain pastures of Collarada mountain (Central Pyrenees, Spain). Preferences for grazing on certain geomorphological features (slope, aspect, and altitude) and different plant communities present in the area were evaluated using the Manly's standardized preference index. The results show that sheep prefer altitudes between 2400 and 2600 m; SE-, SW-, and E-facing sites; and slopes under 20%. The preferred pastures were Festucion eskiae, Primulion intricatae, and Nardion strictae; however, they reject Festucion scopariae communities. This study demonstrates the effectiveness of GPS and GIS technologies in monitoring free-ranging sheep activity, providing valuable data for enhancing pastoral practices and ensuring sustainable pasture use.

The Experimental and In Silico-Based Evaluation of NRF2 Modulators, Sulforaphane and Brusatol, on the Transcriptome of Immortalized Bovine Mammary Alveolar Cells.

Changes during the production cycle of dairy cattle can leave these animals susceptible to oxidative stress and reduced antioxidant health. In particular, the periparturient period, when dairy cows must rapidly adapt to the sudden metabolic demands of lactation, is a period when the production of damaging free radicals can overwhelm the natural antioxidant systems, potentially leading to tissue damage and reduced milk production. Central to the protection against free radical damage and antioxidant defense is the transcription factor NRF2, which activates an array of genes associated with antioxidant functions and cell survival. The objective of this study was to evaluate the effect that two natural NRF2 modulators, the NRF2 agonist sulforaphane (SFN) and the antagonist brusatol (BRU), have on the transcriptome of immortalized bovine mammary alveolar cells (MACT) using both the RT-qPCR of putative NRF2 target genes, as well as RNA sequencing approaches. The treatment of cells with SFN resulted in the activation of many putative NRF2 target genes and the upregulation of genes associated with pathways involved in cell survival, metabolism, and antioxidant function while suppressing the expression of genes related to cellular senescence and DNA repair. In contrast, the treatment of cells with BRU resulted in the upregulation of genes associated with inflammation, cellular stress, and apoptosis while suppressing the transcription of genes involved in various metabolic processes. The analysis also revealed several novel putative NRF2 target genes in bovine. In conclusion, these data indicate that the treatment of cells with SFN and BRU may be effective at modulating the NRF2 transcriptional network, but additional effects associated with cellular stress and metabolism may complicate the effectiveness of these compounds to improve antioxidant health in dairy cattle via nutrigenomic approaches.

Capital Dairy and Livestock: Buffalo Versus Cow Decision

This case delves into the entrepreneurial journey of a dairy business owner, shedding light on the intricacies of the dairy industry within the Pakistani market. It provides a comprehensive overview of the dairy business’s value chain and delves into the life cycle of cattle used for milking. The case also offers insights into the operational aspects of managing a cattle farm and the requisite business systems. Emphasizing the vital components of cattle farm management and the evolving business landscape, it elucidates the crucial roles played by farm workers and the necessary systems for efficient management. Furthermore, the case furnishes valuable information regarding the economics of running a cattle farm, highlighting key cost factors such as food and overhead expenses. The revenue side of the business is intricately linked with the farm management practices, specifically focusing on the yield. The case concludes with the entrepreneur’s desire to reevaluate their business model, shifting from buffalo milk to the exploration of the dynamics involved in the cow milk business.

THE RESULTS OF THE APPROBATION OF METHODS OF SYNCHRONIZATION OF LIBIDO SEXUALIS OF HITSYNCH AND OVSYNCH ON COWS OF MEAT PRODUCTIVITY

The article presents data on the comparative effectiveness of synchronization schemes of the sexual cycle in cattle using the Hitsynch and Ovsynch methods, various GnRH, prostaglandin F2a, and estrogens were used in synchronization schemes to activate sexual processes and increase fertilization. In order to increase their effectiveness, biologically active substances were included in the synchronization schemes. The aim of the study was to determine the effectiveness of various synchronization schemes when biologically active substances are included in them. The authors note that stimulation of the genitals using the methods of synchronization of sexual libido of Hitsynch and Ovsynch with the additional inclusion of biologically active substances in the schemes significantly improves the arrival of cows in libido and increases fertilization. These indicators were more pronounced when synchronizing sexual libido using the Hitsynch method. The novelty of the conducted research is the determination of effective modern schemes of synchronization of sexual libido. It was found that the complex use of hormonal drugs "Surfagon", "Oestrophan" biologically active substances vitamin complex "Tetravit" and estrogenic hormone ECP activates the manifestation of sexual processes stimulates the manifestation of sexual libido and increases the fertilization of cows.

Temporal alteration in ovarian follicle fate with hormonal and hemodynamic perspectives during receptive phase of estrous cycle in endometritic cattle.

The present research was carried out to assess the serum progesterone (P4) concentration and uterine hemodynamics at estrus till ovulation in cyclic cows (N = 130) with healthy or diseased uterus. At estrus, 85 cows were diagnosed with clinical endometritis (CE; n = 44) and sub-clinical endometritis (SCE; n = 41); whereas, 45 cows being served as control namely no endometritis (NE; n = 45) were included in the study. Serum progesterone estimation at 12 - 14 and 40 hr after the onset of estrus and Doppler sonography of both middle uterine arteries were done to envisage the uterine hemodynamics and ovulation. The serum progesterone concentration was significantly higher at 12 - 14 hr after onset of estrus in CE and SCE cows. At 12 - 14 hr after onset of estrus, a cut-off value of ≥ 0.48 ng mL-1 P4 was obtained, above which 22.72% CE, 26.82% SCE and only 8.88% NE cows failed to ovulate within 36 - 40 hr of estrus onset. Among the Doppler indices, pulsatility and resistance indices were significantly higher; whereas, volume and velocity indices were significantly lower in NE cows. In cows diagnosed with CE and SCE, a higher supra-basal P4 concentration, and velocity and volume of blood flow to uterus at estrus negatively affected the duration to ovulation.

7 Contribution of the Beef Industry to the Economy of the Great Plains and Western U.S.: Past, Present, and Future

Abstract The Great Plains and Western U.S. are home to over 60% of all beef cows and over 80% of all cattle on feed in the U.S. While the dynamics of the beef industry in these regions continue to evolve, the significant economic impact generated by the sector remains steadfast. The main objective of this presentation is to provide foundational information on the economic contributions of the beef industry in the Great Plains and Western U.S. to set the stage for subsequent presentations regarding climate adaptation strategies in the sector. The presentation is comprised of three key components. First, a high-level view of the historical progression of the beef industry in the Great Plains and Western U.S. is documented to provide a basis for deeper discussion surrounding the present and future state of the industry. Second, the current conditions of the beef industry in the regions are explored including existing challenges faced by industry participants. Producer profitability in 2023 and the state of the cattle cycle are briefly discussed. Drought conditions are highlighted along with their continuing effects on the industry. Third, we look to the future and dive into prospective opportunities for the sector. The dynamic nature of the beef industry lends itself to adaptation and innovation. As producers and industry participants explore climate adaptation methods going forward, a primary factor in making decisions to alter existing practices or adopt new technologies is the economic return (or lack thereof) generated by proposed strategies. Ongoing work at Kansas State University examines producer sentiment surrounding various strategies, including new technologies aimed at reducing livestock enteric methane emissions. Preliminary findings of this work are outlined along with identified areas for future research in the space. In conclusion, the beef industry significantly contributes to the economy of the Great Plains and Western U.S. This presentation explores the history of the industry in the regions, the present state of the industry and current challenges it faces, and the potential opportunities to come in the future.

142 Estimating the stage of the oestrous cycle in Japanese black beef cattle based on the number of large follicles

142 Estimating the stage of the oestrous cycle in Japanese black beef cattle based on the number of large follicles

Multi‐plant coordination in the U.S. beef packing industry

AbstractMost U.S. beef packers with multiple plants now openly employ multi‐plant coordination. Using a Salop Circular City framework that includes negotiated and formula pricing, we demonstrate that multi‐plant coordination leads to wider spreads between downstream beef prices and upstream fed cattle prices if multi‐plant coordination markdowns outweigh multi‐plant coordination efficiencies. Taken together with market concentration, geography and transportation costs, and cattle cycles and related beef packer capacity utilization, multi‐plant coordination helps explain persistently wide farm‐to‐wholesale beef price spreads. We find that, as cattle inventories decline, a multi‐plant coordinator will permanently shut down a plant before the same plant run as a separate profit center will shut down, which is consistent with packer behavior in recent years. We also demonstrate that adding a strategically‐located packing plant, owned by an entrant firm, can narrow price spreads. This framework is important for ongoing policy discussions regarding the structure, conduct, and performance of the beef packing industry.

An automated system for cattle reproductive management under the IoT framework. Part II: Induction of luteinizing hormone release after gonadotropin releasing hormone analogue delivery with e-Synch

Technologies for automating animal management and monitoring tasks can improve efficiency and productivity of livestock production. We developed the e-Synch system for automated control and monitoring the estrous cycle of cattle through intravaginal hormone delivery and sensing. Thus, our objective was to evaluate luteinizing hormone (LH) concentrations after intravaginal instillation of the Gonadotropin-releasing hormone (GnRH) analogue Gonadorelin with the e-Synch system. This system consists of an intravaginal electronically controlled automated hormone delivery and sensing device integrated with an IoT platform. Lactating Holstein cows with their estrous cycle synchronized were used in two experiments (Exp). In Exp 1, at 48 h after induction of luteolysis, cows (n=5-6 per group) were randomized to receive 100 µg of Gonadorelin through intramuscular (i.m.) injection, 100 µg of Gonadorelin in a 2 mL solution delivered with e-Synch, and an empty e-Synch device. In Exp 2, at 48 h after induction of luteolysis cows (n=6-7 per group) were randomized to receive 100 µg of Gonadorelin i.m., or an intravaginal treatment with e-Synch consisting of 100 or 1,000 µg of Gonadorelin in 2 or 10 mL of solution containing 10% citric acid as absorption enhancer. Circulating concentrations of LH were analyzed with linear mixed models with or without repeated measurements. In Exp 1, cows in the i.m. Gonadorelin treatment had a surge of LH whereas cows in the other two treatments did not have a surge of LH for up to 8 h after treatment. In Exp 2, the 1,000 µg dose of Gonadorelin elicited more LH release than the 100 µg dose, regardless of solution quantity. The overall LH response as determined by area under the curve, mean, and maximum LH concentrations was similar between cows receiving 1,000 µg of Gonadorelin delivered with e-Synch and 100 μg of Gonadorelin i.m. Increasing volume of solution for delivering the same dose of Gonadorelin partially increased LH release only for the 100 µg dose. We conclude that the e-Synch system could be used to automatically release Gonadorelin in a dose and volume that induces a surge of LH of similar magnitude than after i.m. injection of 100 μg of Gonadorelin. Also, the dose of Gonadorelin delivered by e-Synch is more critical than the volume of solution used.

An automated system for cattle reproductive management under the IoT framework. Part I: the e-Synch system and cow responses

The objective of this manuscript was to present the e-Synch system, integrating an intravaginal electronically controlled hormone delivery and sensing device with an IoT platform for remote programming and monitoring. Secondary objectives were to demonstrate system functionality and cow responses to e-Synch. External components of e-Synch include a 3D-printed case with retention wings, a flexible wideband antenna, and silicone membrane for pressure balancing. Internal components include a central control board, battery, wireless charging coil, and two silicone hormone reservoirs connected to individual peristaltic pumps. An accelerometer and a high-accuracy temperature sensor are integrated in the custom printed circuit board (PCB). The IoT platform includes a gateway consisting of Raspberry PI 3 and a CC1352 radiofrequency module that collects sensor data at 915 mHz. Data is transferred to the Google Cloud utilizing the IoT Core service through TCP/IP, and then is pulled by the Pub/Sub service. After routing to a BigQuery table by the Dataflow service, data visualization is provided by Data Studio. Drug delivery protocols are selected using an IOS device app that connects to e-Synch through Bluetooth. Experiments with lactating Holsteins cows were conducted to demonstrate proof-of-concept system functionality and evaluate cow responses. Despite unstable communication and signal discontinuity because of signal strength attenuation by body tissue, devices (n=6) communicated with the IoT platform in 89% (24/27) of use instances. Temperature and accelerometer data were received for at least one 15 min period during an 8 h insertion period from all devices that communicated with the IoT platform. Variation in accelerometer data (± 8.565 m/s2) was consistent with cow activity during experimentation and mean vaginal temperature of 39.1 °C (range 38.6 to 39.5 °C) demonstrated sensor functionality. Hormone release was confirmed in all instances of device use except for one. Cow behavior evaluated through signs of discomfort and pain, and tail raising scores was mostly unaltered by e-Synch. Vaginal integrity and mucus scores also remained unaltered during and after device insertion. In conclusion, the e-Synch device integrated with a controlling app and IoT platform might be used to automate intravaginal hormone delivery and sensing for controlling the estrous cycle of cattle.

Involvement of gap junctions in the increased contraction of bovine oviducts at pre-ovulation observed in vitro.

Spontaneous contraction of oviductal smooth muscle is essential for gamete transport to the fertilization site in mammals. This study sheds light on the mechanism of elevated contraction amplitude in the bovine oviductal isthmus just before ovulation. Rhythmic contraction of the oviducts is essential for transporting gametes and embryos at peri-ovulation; however, its regulatory mechanism during the estrous cycle is unclear. Meanwhile, it is reported that ion currents regulate muscle contraction. Our study aimed to clarify the involvement of ion channels and gap junctions in regulating oviductal motility during the estrous cycle in cattle. The isthmic sections of bovine oviducts collected just after ovulation (0-4 days after ovulation), at the mid-late luteal stage (10-17 days), and at the follicular stage (1-3 days before ovulation) were used in the experiments. The frequency and amplitude of contraction of the oviductal strips in the longitudinal direction were examined using the Magnus system. The frequency was not different among the estrous stages. Conversely, the amplitude was significantly higher at the follicular stage. The blockers of voltage-dependent calcium channels, both IP3 receptor and ryanodine receptors, chloride channel, and gap junction reduced the amplitude. Additionally, mRNA and protein expression of GJA1, a component of the gap junction, in the smooth muscle tissues of the oviductal isthmus were significantly higher in the follicular stage. In addition, estradiol-17β (E2; 1.0 ng/mL) significantly increased GJA1 mRNA expression in cultured smooth muscle tissues after 24 h and GJA1 protein expression in cultured smooth muscle cells after 48 h. These results suggest that local levels of E2 in the oviductal isthmus ipsilateral to an ovary with a dominant follicle support the increased contraction amplitude of bovine ipsilateral oviducts by elevating the gap junction expression.

EFFECT OF BABESIA BIGEMINA AND THEILERIA ANNULATA ON WEIGHT GAIN, MILK YIELD AND ESTROUS CYCLE IN EXPERIMENTALLY INFECTED BOS TAURUS AND BUBALUS BUBALIS

In Pakistan, buffaloes and cattle are the main source for the milk and meat production ultimately having a great economic impact on the socio-economic living of the people. It is believed that blood protozoan parasitic diseases like Babesiosis and Theileriosis caused by tick-borne blood parasite greatly reduce the productivity of the animals. Hence, the study was designed to assessthe effect of Babesia bigemina and Theileria annulata infection on the body weight, estrous cycle and milk production in cattle and buffaloes. Two hundred animals comprising of Bubalus bubalis and Bos taurus (Holstein Friesian, Jersy and Sahiwal) adults and calves were selected for this study. A significant decrease was observed in weight of the affected animals. Delayed maturity was also seen in calves affected with Theileriosis as compared with the control group of calves as the animals gained weight at slower rate after recovery from the disease. Production of milk in control group of Bos taurus and Bubalis bubalis was 14.6 ± 0.23Kg, 13.3 ± 0.2Kg, 11.5 ± 0.4Kg and 12.0 ± 0.31Kg whereas milk production in Babesia affected groups declined to 4.7 ± 0.02Kg, 6.1 ± 0.5Kg, 4.3 ± 0.3Kg and 4.3 ± 0.24Kg respectively. Milk production in control groups of animals of Bos was 13.3 ± 0.2Kg, 14.6 ±0.23Kg and 11.5±0.4Kg whereas milk yield in Theileriosis affected groups decreased to 5.6 ± 0.37Kg, 4.9 ± 0.41Kg and 4.7 ± 0.43Kg respectively. Animals of B. bubalis and Bos. taurus species infected experimentally with Babesia bigemina and Theleria annulata showed irregular and prolonged estrous cycle whereas healthy animals showed normal estrous cycle. The duration of estrous cycle observed in Babesiosis affected animals was 76.0±4.4 days, 65.0±3.29 days, 58±5.2days and 47.0 ± 4.2 days. The duration of estrous cycle in Theileriosis affected Bos species was 63.0 ± 8.57, 68.0 ± 10.0 and 31.0 ± 5.7 days respectively.

Beef Cattle Cycle in the State of Pará, Amazon, Brazil

The production and price behavior of the beef cattle market in the state of Pará, Brazilian Amazon, was evaluated with the objective of characterizing the dynamics of the market and guiding economic decisions made by agents in the beef cattle production chain. Time series of production and prices from the period 1995 to 2021 were analyzed using growth rates and the classical multiplicative method of time series. The cattle herd in Pará showed a growth rate of 4.54% per year from 1995 to 2021, and the slaughter of bovine females fluctuated throughout the historical series with the highest and lowest percentages in the years 2000 and 2011, respectively. There were three complete livestock cycles, differing in duration and amplitude. The average duration of the cycles was 7 years, with a shortening of the cycle over the period of study. Seasonal price indices are higher than 100, which is the annual average index, from September to January and lower than 100 from February to August. The highest price quotations for the arroba of fattened cattle coincide with the off-season period of beef cattle production, which is determined by the carrying capacity of pastures under the influence of weather conditions.

Production and Price Cycles in Beef Cattle in Rondônia State, Brazilian Amazon

The study evaluates the behavior of production and prices in the beef cattle market in Rondônia, Brazilian Amazon. Covering the period from 1995 to 2020, we used statistical analysis based on the classical multiplicative method of time series. Resultingly, we found that the occurrence of annual seasonality in prices, with a reduction in the first half of the year and an increase in the second half of the year, corresponding to the bovine and off-season harvests, respectively. It was possible to observe the existence of three complete livestock cycles, with an average duration of five years. Trend, seasonality, and cycles of livestock in Rondônia, over the last 25 years, expose a series of relevant information for decision-making by agents in the livestock production chain, in addition to contributing to the understanding of the dynamics of this important agricultural market for Rondônia and Brazilian economy.

AI Based Digital Twin Model for Cattle Caring.

In this paper, we develop innovative digital twins of cattle status that are powered by artificial intelligence (AI). The work is built on a farm IoT system that remotely monitors and tracks the state of cattle. A digital twin model of cattle based on Deep Learning (DL) is generated using the sensor data acquired from the farm IoT system. The physiological cycle of cattle can be monitored in real time, and the state of the next physiological cycle of cattle can be anticipated using this model. The basis of this work is the vast amount of data that is required to validate the legitimacy of the digital twins model. In terms of behavioural state, this digital twin model has high accuracy, and the loss error of training reach about 0.580 and the loss error of predicting the next behaviour state of cattle is about 5.197 after optimization. The digital twins model developed in this work can be used to forecast the cattle’s future time budget.

Insights from two independent transcriptomic studies of the bovine corpus luteum during pregnancy.

Several recent studies have used transcriptomics to investigate luteal changes during the maternal recognition of the pregnancy period in ruminants. Although these studies have contributed to our understanding of luteal function during early pregnancy, few attempts have been made to integrate information across these studies and distinguish key luteal transcripts or functions that are repeatably identified across multiple studies. Therefore, in this study, two independent studies of the luteal transcriptome during early pregnancy were combined and compared. In the first study, corpora lutea (CL) from day 20 of pregnancy were compared with CL collected on day 14 of pregnancy, prior to embryonic signaling. The cattle were nonlactating. In the second study, CL from day 20 of pregnancy were compared with CL collected from day 20 cyclic cattle that had been confirmed as not yet undergoing luteal regression. These were lactating cattle. Three methods were used to compare these two datasets, to identify key luteal regulators. In the first method, all transcripts with Benjamini-Hochberg-adjusted P-value (Q value) < 0.05 in both datasets were considered. This yielded 22 transcripts, including several classical interferon-stimulated genes, as well as regulators of transforming growth factor-beta (TGFB) and latent TGFB-binding proteins (LTBP)1 and 2. In the second, less conservative method, all transcripts with P < 0.01 and changed in the same direction in both datasets were considered. This yielded an additional 20 transcripts that were not identified in the first analysis, for a total of 42 common transcripts. These transcripts were regulators of functions such as inflammatory balance and matrix remodeling. In the third method, transcripts with Q < 0.10 were subject to pathway analysis, and common pathways were identified. Retinoic acid signaling and classical interferon signaling pathways were identified with this method. Finally, regulation by interferon tau (IFNT) was investigated. Among the 42 transcripts identified, 32 were regulated by IFNT in cultured luteal cells (Q < 0.05). Among those not regulated by IFNT were LTBP1 and 2, which are TGFB-binding proteins. In summary, common transcripts from two studies of the luteal transcriptome during early pregnancy were combined and shared changes were identified. This not only generated a list of potential key luteal regulators, which were mostly IFNT regulated, but also included transcripts not regulated by IFNT, including LTBP1 and 2.

Changes in fibroblast growth factor receptors-1c, -2c, -3c, and -4 mRNA in granulosa and theca cells during ovarian follicular growth in dairy cattle

The various fibroblast growth factors (FGF) regulate their function via binding to 4 main FGF receptor (FGFR) subtypes and their splice variants, FGFR1b, FGF1c, FGFR2b, FGFR2c and FGFR3c and FGFR4, but which of these FGFR are expressed in the granulosa (GC) and theca cells (TC), the 2 main cell layers of ovarian follicles, or change during follicular development is unknown. We hypothesized that FGFR1c, FGFR2c and FGFR3c (but not FGFR4) gene expression in GC (but not TC) would change with follicular development. Hence, the objective of this study was to determine if abundance of FGFR1c, FGFR2c, FGFR3c, and FGFR4 mRNA change according to follicular size, steroidogenic status, and days post-ovulation during growth of first-wave dominant follicles in Holstein cattle exhibiting regular estrous cycles. Estrous cycles of non-lactating dairy cattle were synchronized, and ovaries were collected on either d 3 to 4 (n = 8) or d 5 to 6 (n = 8) post-ovulation for GC and TC RNA extraction from small (1–5 mm), medium (5.1 to 8 mm) or large (8.1–18 mm) follicles for real-time PCR analysis. In GC, FGFR1c and FGFR2c mRNA relative abundance was greater in estrogen (E2)-inactive (ie, concentrations of E2 < progesterone, P4) follicles of all sizes than in GC from large E2-active follicles (ie, E2 > P4), whereas FGFR3c and FGFR4 mRNA abundance did not significantly differ among follicle types or days post-estrus. In TC, medium E2-inactive follicles had greater FGFR1c and FGFR4 mRNA abundance than large E2-active and E2–inactive follicles on d 5 to 6 post-ovulation whereas FGFR2c and FGFR3c mRNA abundance did not significantly differ among follicle types or day post-estrus. In vitro experiments revealed that androstenedione increased abundance of FGFR1c, FGFR2c and FGFR4 mRNA in GC whereas estradiol decreased FGFR2c mRNA abundance. Neither androstenedione nor estradiol affected abundance of the various FGFR mRNAs in cultured TC. Taken together, the findings that FGFR1c and FGFR2c mRNA abundance was less in GC of E2-active follicles and FGFR1c and FGFR4 mRNA was greater in TC of medium inactive follicles at late than at early growing phase of the first dominant follicle support an anti-differentiation role for FGF and their FGFR as well as support the idea that steroid-induced changes in FGF and their receptors may regulate selection of dominant follicles in cattle.

Onset of normal cycles in postpartum anovulatory dairy cattle treated with kisspeptin.

The efficacy of a long-acting synthetic derivative of kisspeptin (Kp) to initiate normal oestrous cycles was tested in 24 mixed-aged, Holstein-Friesian cows that were 18–25 days postpartum on the day of treatment (D0). Groups of eight cows received saline (Sal) vehicle by intramuscular injection at 8:00 and 16:00 h (Sal-Sal), Kp at 8:00 h and vehicle at 16:00 h (Kp-Sal) or Kp on both occasions (Kp-Kp). The Kp dose was 15 nmol per 60 kg body weight. The ovaries of the cows were examined daily by ultrasonography between D4 and D14. Blood samples were collected from a tail vessel at 0, 2, 4, 8, 10 and 12 h relative to the time of the first injection for luteinizing hormone (LH) and follicle-stimulating hormone assay. Additional samples were collected daily from D4 until D14 and D19, 22, 26 and 29 for progesterone assay. LH surge-like responses were observed in cows treated with Kp at 8:00 h. Ovulation was consistently induced by Kp within 48 h when a dominant ovarian follicle of at least 10 mm in diameter was observed (8/14) but in no cases (6/14) during a new wave of ovarian follicular development comprising follicles <10 mm in diameter. The subsequent ovulatory cycle was of normal length in most cases as compared with short 8– to 12-day cycles observed in spontaneously ovulating cows. We conclude that Kp treatment can induce ovulation in postpartum dairy cows, with ensuing oestrous cycles of normal length, if administered when a mature dominant follicle is present in the ovaries.Lay summaryCow fertility is important for efficient, profitable dairy farming. Cows that take too long after calving to become fertile are problematic. We tested a synthetically made, long-acting hormone called kisspeptin (Kp) to advance the time that cows become fertile after calving. Twenty-four dairy cows that had been calved for 3–4 weeks were used. One group of eight cows received an injection of Kp at the morning milking, another eight cows received Kp at both the morning and afternoon milking, while the last group of eight cows served as untreated controls. Kp treatment caused a desirable hormone response from the cows’ brain. Normal oestrous cycles resulted, but only when a mature follicle was present in the ovary. Further study is required to analyse whether the use of a long-acting Kp drug could be used as an effective treatment for stimulating dairy cows to become more fertile after calving.

Endometrial glycogen metabolism on days 1 and 11 of the reproductive cycle in dairy cows

Embryos need glucose or fructose to remain viable; however, it is not well understood how secretion of these carbohydrates is regulated. This study was conducted to evaluate endometrial glycogen and associated enzymes on Days 1 and 11 of the estrous cycle (Day 0 = behavioral estrus) in cattle. Diastase-liable periodic acid–Schiff (PAS) staining of luminal epithelia decreased 81 % between Days 1 and 11. Similarly, glycogen content of glandular epithelia was 66 % less on Day 11 than Day 1. There was dense PAS staining in the lumen of some glands, and this staining was removed when there was pretreatment with diastase. Based on western blot results, there was no difference in glycogen metabolizing enzymes between Days 1 and 11. Results from conducting immunohistochemistry procedures indicated hexokinase 1 was more abundant in the epithelial cells than stroma, but immunostaining was not different between Day 1 and 11. In contrast, phospho-glycogen synthase was undetectable on Day 1 but was present in glandular epithelia on Day 11. Glycogen synthase was localized to the epithelia, and was in larger abundance on Day 1. The abundance of glycogen phosphorylase was greater in the epithelium than stroma and on Day 11 than 1. Furthermore, glucose-6-phosphatase 3 was more abundant in the epithelium on both Days 1 and 11. In conclusion, in the uterus of cattle glycogen is stored in a reproductive cycle-dependent manner. Glucose released from endometrial glycogen stores could potentially be utilized by the endometrium or secreted into the uterine lumen.

Relationships among feed efficiency traits across production segments and production cycles in cattle.

Understanding the relationships between feed efficiency traits measured in different stages of production is necessary to improve feed efficiency across the beef value chain. The objective of this study was to evaluate relationships among feed efficiency traits measured as growing heifers and breeding females and in their progeny in three full production cycles, and relationships of dam residual feed intake (RFI) with lifetime and lifecycle cow efficiency traits. Data were collected on 160 mixed-breed heifers from 240 d of age to weaning of their third progeny, and postweaning performance of progeny until harvest in experiments initiated in 1953, 1954, 1959, 1964, 1969, and 1974. Individual feed offered was recorded daily, and feed refusals measured every 28 d. Milk yield was measured at 14-d intervals throughout lactation by machine or hand milking. Females and progeny were weighed at 28-d intervals and progeny were harvested at a constant endpoint of live grade or age depending upon the experiment. Feed efficiency traits of RFI and residual BW gain (RG) were computed as the residual from linear regression for developing heifers, dams (RFI and residual energy-corrected milk [RECM]), and postweaning progeny. Feed:gain ratio (FCR) was computed for developing heifers and postweaning progeny, and feed:milk energy ratio (FME) was computed for dams. Various measures of cow efficiency were calculated on either a life cycle or lifetime basis using ratios of progeny and dam weight outputs to progeny and dam feed inputs. Pearson correlations were computed among traits adjusted for a random year-breed-diet group effect. Heifer RFI (0.74) and RG (−0.32) were correlated (P ≤ 0.05) with dam RFI in parity 1 only, but were not correlated (P > 0.05) with dam RECM in any parity. Heifer RFI was correlated (P ≤ 0.05) with progeny RFI (0.17) in parity 3 only. Heifer FCR was not correlated with dam FME or progeny FCR in any parity. Dam RFI was weakly correlated (r = 0.25 to 0.36; P ≤ 0.05) among parities, whereas dam FME and RECM were strongly correlated (r = 0.49 to 0.72; P ≤ 0.05) among parities. Dam RFI in parity 1 and 2 was weakly correlated (r = −0.20 to −0.33; P ≤ 0.05) with cow efficiency ratios that included dam weight as an output, whereas dam RFI in parity 3 was not correlated with any cow efficiency ratio. In conclusion, feed efficiency traits were poorly correlated across production segments, but moderately repeatable across production cycles.