Late-gestation heat stress alters placental structure and function in multiparous dairy cows.

The placenta plays a pivotal role in fetal development and the dam's subsequent lactation performance, because it facilitates nutrient transfer, heat dissipation, and gas exchange with the growing fetus, and regulates key hormones essential for mammary gland development. Heat stress experienced during gestation and lactation can significantly reduce the placenta's capacity to perform these critical functions. To investigate the impact of heat stress, trials were conducted over the summer months of 2020, 2022, and 2023 in Florida.

Rumen-protected methionine supplementation during the transition period under artificially induced heat stress: Effects on cow-calf performance.

Dairy cows experiencing heat stress (HS) during the precalving portion of the transition period give birth to smaller calves and produce less milk and milk protein. Supplementation of rumen-protected methionine (RPM) has been shown to modulate protein, energy, and placenta metabolism, making it a potential candidate to ameliorate HS effects. We investigated the effects of supplementing RPM to transition cows under HS induced by electric heat blanket (EHB) on cow-calf performance.

Inner limiting Membrane Peel Extends Calcium Imaging of Retinal Ganglion Cell Activity Beyond the Fovea in Non-Human Primate.

High resolution retinal imaging paired with intravitreal injection of a viral vector coding for the calcium indicator GCaMP has enabled visualization of activity dependent calcium changes in retinal ganglion cells (RGCs) at single cell resolution in the living eye. The inner limiting membrane (ILM) is a barrier for viral vectors, restricting transduction to a ring of RGCs serving the fovea in both humans and non-human primates (NHP). We evaluate peeling the ILM prior to intravitreal injection as a strategy to expand calcium imaging beyond the fovea in the NHP eye in vivo.

Rumen-protected methionine supplementation during the transition period under artificially induced heat stress: impacts on cow-calf performance.

Dairy cows experiencing heat stress (HS) during the pre-calving portion of the transition period give birth to smaller calves and produce less milk and milk protein. Supplementation of rumen-protected methionine (RPM) has been shown to modulate protein, energy, and placenta metabolism, making it a potential candidate to ameliorate HS effects. We investigated the effects of supplementing RPM to transition cows under HS induced by electric heat blanket (EHB) on cow-calf performance.

Effects of thermal stress on calf welfare.

Cold and heat stress present welfare challenges for dairy calves. The consequences of thermal stress on biological functioning have been well documented, and many housing and management strategies have been evaluated to mitigate those detrimental impacts. In cold weather, mitigation strategies have largely focused on nutritional interventions or limiting heat loss with resources such as bedding or jackets.

Carryover effects of maternal late-gestation heat stress on granddaughters' growth and mammary gland development.

Maternal (F) exposure to late-gestation heat stress reduces their daughter's (F) mammary gland fat pad (FP) mass, parenchyma (PAR) mass, and epithelial cell proliferation when evaluated at birth and weaning, and the daughters go on to produce less milk in their first lactation. Herein, we investigated the effect of maternal late-gestation heat stress on whole-body growth and mammary development of their granddaughters (F). Multiparous F cows had access to heat abatement (n = 41, shade, and active cooling via fans and water soakers) or not (n = 41, shade only) for the last 56 d of gestation during a subtropical summer.

Long-term growth, feed efficiency, enteric methane emission, and blood metabolite responses to in utero hyperthermia in Holstein heifers.

Dairy producers are experiencing production and animal welfare pressures from the increasing frequency and severity of heat stress events due to global climate change. Offspring performance during the preweaning and lactating periods is compromised when exposed to heat stress during late gestation (in utero). However, knowledge of the lingering effects of in utero heat stress on yearling dairy heifers is limited.

Programming effects of intrauterine hyperthermia on adrenal gland development.

Maternal heat stress during late pregnancy can lead to intrauterine hyperthermia and affect fetal hypothalamic-pituitary-adrenal axis development and function. Herein, we investigated the effects of chronic environmental heat stress exposure of Holstein cows in the last 2 mo of gestation on their offspring's adrenal gland histomorphology and transcriptome. Cows in their last 54 ± 5 d of gestation were either heat stressed (housed under the shade of a freestall barn) or provided heat stress abatement via active cooling (via water soakers and fans) during a subtropical summer (temperature-humidity index >68).

Review: Phenotypic and molecular evidence of inter- and trans-generational effects of heat stress in livestock mammals and humans.

Internal and external factors can change an individual's phenotype. A significant external threat to humans and livestock is environmental heat load, a combination of high ambient temperatures and humidity. A heat stress response occurs when an endothermal animal is exposed to a heat load that challenges its' thermoregulation capacity.

Late-gestation heat stress in Holstein dams programs in utero development of daughter's germline, triggering skin and hair morphology adaptations of granddaughters.

Homeostasis and thermoregulation are influenced by the interplay of hair coat and skin characteristics. Our previous work indicated that hair and skin adaptations, triggered by in utero heat stress, affect thermoregulation in postnatal life. Herein, we investigate multigenerational carry-over effects of late-gestation heat stress on hair and skin characteristics beyond the first generation.

Actively ventilating calf hutches using solar-powered fans: Effects on hutch microclimate and calf thermoregulation.

Although active ventilation via fans is an effective and widely adopted heat abatement method for use with adult dairy cattle, it has yet to be investigated in outdoor hutch-housed dairy calves despite most US calves being raised in such systems. We investigated a solar-powered fan system for outdoor calf hutches and its effect on hutch microclimate and calf thermoregulation. During summer, a 3 × 3 Latin square was replicated 4 times (n = 12 preweaning heifers) with 4-d exposure periods to minimally (CON; rear windows closed), passively (PASS; rear windows opened), or actively (ACT; solar-powered fan, activated at dry bulb temperature [T] > 21°C) ventilated hutch systems.

Intravenous infusion of 5-hydroxytryptophan to mid-lactation Holstein cows transiently affects milk production and circulating amino acid concentrations.

In dairy cows, the lactating mammary glands synthesize serotonin, which acts in an autocrine-paracrine manner in the glands and is secreted into the periphery. Serotonin signaling during lactation modulates nutrient metabolism in peripheral tissues such as adipose and liver. We hypothesized that the elevation of circulating serotonin during lactation would increase nutrient partitioning to the mammary glands, thereby promoting milk production.

Untargeted Metabolomic Analysis of Lactation-Stage-Matched Human and Bovine Milk Samples at 2 Weeks Postnatal.

Epidemiological data demonstrate that bovine whole milk is often substituted for human milk during the first 12 months of life and may be associated with adverse infant outcomes. The objective of this study is to interrogate the human and bovine milk metabolome at 2 weeks of life to identify unique metabolites that may impact infant health outcomes. Human milk ( = 10) was collected at 2 weeks postpartum from normal-weight mothers (pre-pregnant BMI < 25 kg/m) that vaginally delivered term infants and were exclusively breastfeeding their infant for at least 2 months.

Unraveling the immune and metabolic changes associated with metritis in dairy cows.

The objective was to unravel the peripartum immune and metabolic changes associated with metritis in Holstein cows. Holstein cows (n = 128) had blood collected at -14, 0, 3, and 7 d relative to parturition (DRP). Flow cytometry was used to evaluate blood leukocyte counts, proportions, and activation.

Artificial shade as a heat abatement strategy to grazing beef cow-calf pairs in a subtropical climate.

Grazing livestock in subtropical and tropical regions are susceptible to prolonged exposition to periods of extreme environmental conditions (i.e., temperature and humidity) that can trigger heat stress (HS).

Paraneoplastic Neurological Syndromes of the Central Nervous System: Pathophysiology, Diagnosis, and Treatment.

Paraneoplastic neurological syndromes (PNS) include any symptomatic and non-metastatic neurological manifestations associated with a neoplasm. PNS associated with antibodies against intracellular antigens, known as "high-risk" antibodies, show frequent association with underlying cancer. PNS associated with antibodies against neural surface antigens, known as "intermediate- or low-risk" antibodies, are less frequently associated with cancer.

Amplifying local serotonin signaling prior to dry-off hastens mammary gland involution and redevelopment in dairy cows.

The monoamine serotonin (5-hydroxytryptamine, 5-HT) has been reported to inhibit milk protein gene expression and increase mammary epithelial cell (MEC) tight junction permeability after milk stasis. We hypothesized that increasing serotonin synthesis and signaling within the mammary epithelium before milk stasis would increase systemic and local involution markers, and downregulate the expression of milk protein and tight junction during involution, leading to more efficient tissue growth during the redevelopment phase. Herein, we examined the outcomes of increasing local mammary 5-HT synthesis before milk stasis on involution biomarkers, mammary gland microstructure, and gene and protein expression during the dry period.

Serotonin alters the response to a glucose challenge in lactating cows.

Energy partitioning in lactating cows affects milk production, feed efficiency, and body reserves, with the latter having health implications for the transition into the following lactation. One molecule likely involved in the regulation of energy partitioning is serotonin. The objective of this experiment was to explore how increasing circulating serotonin, by intravenous infusion of the serotonin precursor 5-hydroxytryptophan (5-HTP), affects metabolic responses to a glucose challenge in midlactation cows as a means to manipulate energy partitioning.

Programming effects of late gestation heat stress in dairy cattle.

The final weeks of gestation represent a critical period for dairy cows that can determine the success of the subsequent lactation. Many physiological changes take place and additional exogenous stressors can alter the success of the transition into lactation. Moreover, this phase is pivotal for the final stage of intrauterine development of the fetus, which can have negative long-lasting postnatal effects.

Methods for detecting heat stress in hutch-housed dairy calves in a continental climate.

Dairy calves exposed to solar radiation, elevated ambient temperature, and humidity are at risk of impaired welfare and productivity. Initial detection of thermal discomfort requires determination of optimal heat stress indicators and thresholds. Such values have recently been established in calves in chronic, subtropical, and acute continental environments but not in continuous, temperate conditions.

Prepartum heat stress in dairy cows increases postpartum inflammatory responses in blood of lactating dairy cows.

Uterine diseases and heat stress (HS) are major challenges for the dairy cow. Heat stress alters host immune resilience, making cows more susceptible to the development of uterine disease. Although HS increases the incidence of uterine disease, the mechanisms by which this occurs are unclear.

Early-life heat stress exposure impacts dairy calf feeding and thermoregulatory behavior.

Heat stress has well-known influences on dairy calf physiology, but less is understood about calf behavioral responses to heat stress. Herein, we evaluated milk replacer intake, standing activity, and lying behaviors of calves exposed to prenatal or postnatal heat stress or both. Holstein calves were born to dams experiencing heat stress (HT; shade of a freestall barn) or cooling (CL; shade, fans, and soakers) during late gestation [~44 d before calving, prenatal; mean daily temperature-humidity index (THI) = 78].