Late gestation heat stress alters O regulation in placenta and neonatal heifers.

Introduction: Maternal hyperthermia (i.e. heat stress) can adversely affect placental development and function, with severity varying based on pregnancy stage.

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).

Use of a commercial feed supplement based on yeast products and microalgae with or without nucleotide addition in calves.

The use of feed additives with antioxidant and immune response modulatory activity could be a useful strategy in suckling calves to reduce morbidity and mortality. This strategy is based on several feed additives tested for these purposes. The aim of the paper is the examination of a commercial feed additive for adult cows for use in calves, with and without nucleotide supplementation.

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.

In utero hyperthermia in late gestation derails dairy calf early-life mammary development.

Prenatal hyperthermia has immediate and long-term consequences on dairy cattle growth, immunity, and productivity. While changes in the molecular architecture are reported in the mature mammary gland (MG), any influence on early-life mammary development is unknown. Herein, we characterize the impact of late-gestation in utero heat stress on heifer mammary gross and cellular morphology at early-life developmental stages (i.

Effect of calving season on metritis incidence and bacterial content of the vagina in dairy cows.

Heat stress and uterine diseases, including metritis and endometritis, both reduce milk yields and reduce reproductive performance. Bacterial growth is promoted by elevated temperature while heat stress reduces host immune cell function, but it is not known whether increased environmental temperature promotes uterine disease by altering host immunity or bacterial growth. We hypothesize that seasonal variations in environmental temperature influence metritis incidence in the dairy cow independent of bacterial prevalence in the reproductive tract.

Investigating the Use of Dry Matter Intake and Energy Balance Prepartum as Predictors of Digestive Disorders Postpartum.

One objective was to evaluate the association of dry matter intake as a percentage of body weight (DMI%BW) and energy balance (EB) prepartum and postpartum, and energy-corrected milk (ECM) postpatum with digestive disorders postpartum. For this, ANOVA was used, and DMI%BW, EB, and ECM were the outcome variables, and left displaced abomasum (LDA), indigestion, and other digestive disorders (ODDZ) were the explanatory variables. The main objective was to evaluate prepartum DMI%BW and EB as predictors of digestive disorders.

Dry Period Heat Stress Impacts Mammary Protein Metabolism in the Subsequent Lactation.

Dry period heat stress impairs subsequent milk production, but its impact on milk protein content and yield is inconsistent. We hypothesize that dairy cow exposure to dry period heat stress will reduce milk protein synthesis in the next lactation, potentially through modified amino acid (AA) transport and compromised mTOR signaling in the mammary gland. Cows were enrolled into heat-stressed (dry-HT, = 12) or cooled (dry-CL, = 12) treatments for a 46-day dry period then cooled after calving.

Endocrine Signals Altered by Heat Stress Impact Dairy Cow Mammary Cellular Processes at Different Stages of the Dry Period.

Hormonal alterations occurring under late gestation heat stress may disturb mammary gland remodelling, resulting in a reduced milk yield during the subsequent lactation. We investigated the effects of an altered endocrine environment on mammary gene expression at different stages of the dry period. Mammary gland biopsies from in vivo-cooled (CL) or heat-stressed (HT) cows were collected at d 3 and 35 relative to dry-off and divided into explants.

MILK Symposium review: Identifying constraints, opportunities, and best practices for improving milk production in market-oriented dairy farms in Sri Lanka.

Dairy is the most important subsector in the Sri Lankan livestock industry, due to the need to address the growing demand for fresh milk and milk products, and because of its potential influence on the rural economy. The USDA Food for Progress program awarded a 4.5-year Market-Oriented Dairy project to International Executive Service Corps, a not-for-profit organization based in Washington, DC.

MILK Symposium review: Improving control of mastitis in dairy animals in Nepal.

Dairy animals are an important source of income, food, and nutritional security, and improvements in the productivity of dairy animals substantially improve the wellbeing of smallholder dairy farmers. As in other developing countries, dairy animals are key for rural livelihoods in Nepal but often suffer from mastitis-a production disease causing economic losses to farmers, challenges to the dairy processing industry, and possible health hazards to consumers. Studies show that the prevalence of subclinical mastitis in Africa and Asia typically exceeds 50%, threatening animal wellbeing, farmers, dairy processors, and consumers.

MILK Symposium Introduction: Dairy production in developing countries.

In low- and middle-income countries (LMICs), dairy production is highly valued, and demand for milk is projected to continue to increase markedly over the next few decades. This presents a tremendous opportunity to improve the nutrition, health, incomes, and livelihoods of millions of people with the high-quality protein and bioavailable micronutrients in dairy products. However, low dairy consumption levels, due to low affordability, accessibility, and availability, still typify several LMICs.

Effect of heat stress during the early and late dry period on mammary gland development of Holstein dairy cattle.

Dry period heat stress impairs subsequent milk yield. Our objective was to evaluate the effect of heat stress or cooling during the early and late dry period on mammary gland gene expression and microstructure. Cows were dried off ∼45 d before expected parturition and randomly assigned to 1 of 2 treatments: heat stress (HT, n = 39) or cooling (CL, n = 39) during the first 21 d of the dry period.

Heat Stress Impacts Immune Status in Cows Across the Life Cycle.

Heat stress has a myriad of effects on dairy cattle across the life cycle. Whereas, the most commonly recognized impacts are associated with production responses, emerging evidence indicates that heat stress profoundly alters the immune response of calves and cows, from the prenatal stage through lactation. For example, heat stress reduces passive immune transfer regardless of colostrum source, relative to normothermic conditions in late gestation.

Dry period heat stress induces microstructural changes in the lactating mammary gland.

The bovine dry period is a non-lactating period between consecutive lactations characterized by mammary gland involution and redevelopment phases to replace senescent mammary epithelial cells with active cells primed for the next lactation. Dairy cows exposed to heat stress during the dry period experience milk yield reductions between 3-7.5 kg/d in the next lactation, partially attributed to processes associated with mammary cell growth and turnover during the dry period.

In Utero Heat Stress Programs Reduced Performance and Health in Calves.

Heat stress during late gestation adversely impacts the developing calf. Calves that experience heat stress are born at a lower bodyweight and those deficits persist at least until puberty. In utero heat stress reduces passive transfer and calf survival.

Effect of heat stress during early, late, and entire dry period on dairy cattle.

Cooling during the entire dry period abates the negative effects of heat stress postpartum, yet the temporal relationship of cooling (i.e., early or late dry period) to performance is unknown.

PHYSIOLOGY SYMPOSIUM: Effects of heat stress during late gestation on the dam and its calf12.

Heat stress during late gestation in cattle negatively affects the performance of the dam and its calf. This brief exposure to an adverse environment before parturition affects the physiological responses, tissue development, metabolism, and immune function of the dam and her offspring, thereby limiting their productivity. During the dry period of a dairy cow, heat stress blunts mammary involution by attenuating mammary apoptosis and autophagic activity and reduces subsequent mammary cell proliferation, leading to impaired milk production in the next lactation.

In utero exposure to thermal stress has long-term effects on mammary gland microstructure and function in dairy cattle.

Earth's rising temperature has substantial repercussions for food-producing animals by increasing morbidity and mortality, diminishing reproductive potential, and reducing productivity. In the dairy industry this equates to massive losses in milk yield, which occur when cows are exposed to heat stress during lactation or during the non-lactating period between lactations (i.e.

Impact and Mitigation of Heat Stress for Mastitis Control.

Heat stress abatement is not difficult to implement, and at a minimum all cows should have shade access regardless of housing or pasture access. Active cooling of lactating cows and dry cows can have dramatic effects on productive function and enhance immune status as well. Whereas the method of abatement may vary depending on humidity conditions at a particular location, cooling can be achieved in any environment.

RNA-Seq reveals novel genes and pathways involved in bovine mammary involution during the dry period and under environmental heat stress.

The bovine dry period is a dynamic non-lactating phase where the mammary gland undergoes extensive cellular turnover. Utilizing RNA sequencing, we characterized novel genes and pathways involved in this process and determined the impact of dry period heat stress. Mammary tissue was collected before and during the dry period (-3, 3, 7, 14, and 25 days relative to dry-off [day 0]) from heat-stressed (HT, n = 6) or cooled (CL, n = 6) late-gestation Holstein cows.

Liver proteomic analysis of postpartum Holstein cows exposed to heat stress or cooling conditions during the dry period.

Heat stress negatively affects cow performance, compromises immune function, and increases susceptibility to metabolic disorders, particularly during the dry period and as cows transition from gestation to lactation. Metabolic adaptations of the liver are critical for successful transition, yet it is unclear how heat stress affects metabolic pathways within the liver at the proteomic level. The objective of this study was to investigate the liver proteome of postpartum cows that were cooled or heat stressed during the dry period to gain insight into how protein expression is altered by prior heat stress and may contribute to performance and disease outcomes.

Effects of feeding an immunomodulatory supplement to heat-stressed or actively cooled cows during late gestation on postnatal immunity, health, and growth of calves.

Heat stress during late gestation negatively affects the physiology, health, and productivity of dairy cows as well as the calves developing in utero. Providing cows with active cooling devices, such as fans and soakers, and supplementing cows with an immunomodulating feed additive, OmniGen-AF (OG; Phibro Animal Health Corporation), improves immune function and milk yield of cows. It is unknown if maternal supplementation of OG combined with active cooling during late gestation might benefit the developing calf as well.