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Questions and Concerns

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Thomas Sanchez
Thomas Sanchez

Bovine Reproduction

Fertility in water buffalo (Bubalus bubalis) is considerably lower than that in cattle (Bos taurus and Bos indicus). Poor breeding efficiency is attributed to late onset of puberty, seasonality, poor estrus expression, and long calving intervals. Accurate estrus detection is a prerequisite for efficient reproductive management. Established reproductive management techniques in cattle can be successfully applied to water buffalo because of the similarities in the anatomy, physiology, and endocrinology of reproduction between the two genera.

Bovine Reproduction

For this reason, in this preliminary investigation, we performed three explorative studies in vitro and in vivo. Only one paper [35] described the effects of platelet rich plasma on morula and blastocysts in vitro production. In our study and in our experimental conditions (i.e. platelet concentration at 1x 109/ml), at first we studied the effect of PC on in vitro embryo development using two different percentages (respectively 5 % and 10 %) of PC as a partial or complete replacement of FCS. The rate of blastocyst production and the total cells number of the blastocysts were statistically increased in the medium with 5 % PC and 5 % FCS when compared to both the control and medium with 10 % PC. Platelets release many growth factors, including FGF, TGF-6, PDGF and EGF [36, 37] that can stimulate bovine embryo development [38, 39]. Indeed, Munson et al. [40] demonstrated that TGF-6 and PDGF act synergistically to promote proliferation of both bovine trophoblastic cells and endometrial epithelial cells during in vitro culture. Moreover, EGF in vivo is produced by endometrial cells and its receptors have been detected in the embryo itself, where EGF acts through the phosphorylation of membrane proteins as a mitogen, promoting DNA and RNA synthesis. As pregnancy progresses, the increased production of EGF enhances trophoblast differentiation [41], promoting cell attachment and embryo development [23]. Fibronectin and other glycoproteins are also released from platelets after aggregation, and Larson et al. [42] discovered that a serum-free medium supplemented with fibronectin provides the extracellular matrix required by the embryo to develop to the blastocyst stage during in vitro culture. In a speculative interpretation, the embryo culture systems supplemented with PC may have provided TGF-6, PDGF and the matrix of extracellular fibronectin necessary to support the development of embryo during in vitro culture, thus replicating the uterine microenvironment appropriate for embryo growth, viability, and for cytokine secretion [23]. It is possible that the low rate of embryos obtained in the medium with 10 % PC, compared to control, results from an excess of factors that may have had an inhibitory effect on the embryo development.

Nerve growth factor-β (NGF), initially recognized as a neurotrophin involved in regulating neuronal survival and differentiation, was also later revealed as a ubiquitous seminal plasma protein in mammals. In South American camelids, NGF was initially named ovulation-inducing factor and a dose-dependent luteotropic effect was also reported in llamas. Although NGF was present in the seminal plasma of bulls, the first studies only indicated a potential role on regulation of sperm physiology. The breakthrough discovery of NGF ability to induce ovulation in camelids led to a series of studies investigating the potential functions of NGF within the female reproductive system. In the bovine, a potential luteotropic effect of NGF was perceived as potential tool to overcome the current issues with early embryonic losses attributed at least in part to luteal insufficiency and failed maternal recognition of pregnancy. The aims of this review are to discuss recent advancements in the understanding of the biological roles of NGF in the bovine species. The insights of recent studies with NGF administered in cattle include enhancement of steroidogenesis, luteal formation, and function through increased release of LH, and downstream effect of increased expression of interferon-stimulated genes. In addition, a positive association with sire conception rates; the determination that is produced in the ampulla and vesicular glands of bulls and that is secreted into the sperm-rich fraction of the ejaculate; and the absence of improved post-thaw sperm motility, viability, acrosome integrity, or chromatin stability in ejaculated or epididymal derived sperm supplemented with purified NGF is also discussed.

The vaginal microbiota has been studied in animal reproduction and fertility, in particular little information of vaginal microbes in reference to bovine reproduction and pheromone production is known. The vaginal mucosa in healthy cow is colonized by an equilibrated and dynamic composition of aerobic, facultative anaerobic and obligate anaerobic microbes. Cervico-vaginal mucus (CVM) composition, viscosity and volume vary with the cyclicity and health status of the reproductive tract. In addition, CVM contains pheromones, volatile compounds, and proteins that attract males for coitus. Commensal microbiota plays a key role in protection of the genital tract from pathogenic microbes by competition effect. In the bovine species, the microbial composition, its abundance and diversity in the female gut, vagina, urine, saliva, and feces, and the associated chemical communication remains poorly documented. The impact of microbes in the reproductive tract of cow, buffalo and certain mammals are discussed in this review. Since the microbial population diversity of CVM is modified during estrus phase it presumes that it may have a role for pheromone production in conspecific. Herein, we would like to critically discuss the current state of knowledge on microbially produced signals in animals and the role of genital and CVM microbiota in estrous cycle and pregnancy.

This study describes an outbreak of bovine herpesvirus 1 (BHV1) infections in a dairy herd with special reference to disease symptoms, reproductive performance and milk production losses. The study was carried out with a dairy herd consisting of 98 lactating animals. All animals were housed in the same freestall barn with intensive contact between all animals. An outbreak of BHV1 was induced by injecting three seropositive cows with dexamethasone. During the outbreak, no clinical signs were observed in any of the newly infected animals. At the time of infection, a significant drop in milk production was noted in animals that were initially-seronegative. The production loss was estimated at approximately 9.5 1 per infected animal during the infectious period of 14 days. None of the pregnant cows aborted because of BHV1 infection. During 50 days before BHV1 circulation, there was a significant decrease in the number of successful inseminations in both seronegative and seropositive animals. Therefore, it is doubtful that early pregnancies were terminated by BHV1 infection. The proportion of successful inseminations during the BHV1 circulation in this herd, and in the period thereafter, did not significantly differ from the baseline period.

The mathematics demonstrate the importance of having most of your herd calve early in the breeding season so they have multiple opportunities to get pregnant before the breeding season ends. Because a bovine pregnancy lasts 283 days, a cow/heifer must rebreed within 82 days to maintain a yearly calving interval. The average length of time before a cow starts cycling after calving is 40-60 days. Therefore, if cows start calving 30-40 days after the start of calving season, it is unlikely that they will be cycling at the beginning of the breeding season. First calf heifers take an average of 80-100 days to start cycling after calving.

Copyright 2022 Fontes and Oosthuizen. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

Undesirable microbial infiltration into the female bovine reproductive tracts, for example during calving or mating, is likely to disturb the commensal microflora. Persistent establishment and overgrowth of certain pathogens induce reproductive diseases, render the female bovine reproductive tract unfavourable for pregnancy or can result in transmission to the foetus, leading to death and abortion or birth abnormalities. This review of culture-independent metagenomics studies revealed that normal microflora in the female bovine reproductive tract is reasonably consistently dominated by bacteria from the phyla Bacteroidetes, Firmicutes, Proteobacteria, following by Actinobacteria, Fusobacteria and Tenericutes. Reproductive disease development in the female bovine reproductive tract was demonstrated across multiple studies to be associated with high relative abundances of bacteria from the phyla Bacteroidetes and Fusobacteria. Reduced bacterial diversity in the reproductive tract microbiome in some studies of cows diagnosed with reproductive diseases also indicated an association between dysbiosis and bovine reproductive health. Nonetheless, the bovine genital tract microbiome remains underexplored, and this is especially true for the male genital tract. Future research should focus on the functional aspects of the bovine reproductive tract microbiomes, for example their contributions to cattle fertility and susceptibility towards reproductive diseases.

In general, cattle reproduction (with a maximum of one pregnancy per year) is less efficient as compared to other livestock species which give birth to a litter or are oviparous [1,2,3,4].. On the herd level, the number of calves born and raised per breeding cycle is inevitably vital for economically sustainable dairy and beef production, as well as heifer replacements [5, 6]. Therefore, maintaining the bovine reproduction performance at an optimal level is a priority in cattle industries. Bovine reproduction performance is a multifactorial trait and can be affected by both infectious and non-infectious factors. Examples of non-infectious factors are genetic variation in fertility, environmental factors and nutrition [7, 8]. Infectious factors are primarily linked to persistent microbial colonization, which can lead to inflammation and compromised reproductive performances in various forms, including distorted reproductive cycle, reduced conception rate, increased risk of abortion, stillbirth and extended calving seasons [9,10,11,12]. 041b061a72


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