Identification of Genes Expressed in the Anterior Pituitary Associated With Water Restriction in Beef Cattle

Water is an essential nutrient and is required for growth, metabolism, lactation, and reproduction. Without water, livestock production would not be possible. Despite its importance, water requirements in livestock have not received much attention from the research community since the 1950s. The most recent edition of the Nutrient Requirements of Beef Cattle (8th edition) relies on literature from the 1950s or earlier for defining water requirements in beef cattle. Since the time these requirements were estimated, much has changed with regards to body size, genetics, and productivity of our livestock herds, including beef cattle. Global surface temperatures have increased in the last 20 years leading to climate variability, drought conditions, and desertification. Range animals may be exposed to more variable water supplies. Nutrigenomics research in livestock has largely focused on interactions between dry matter components of the diet and genomics. Transcriptome and genomic variation in response to changes in water intake have not been studied to our knowledge. Given the importance of water in livestock diets, this gap in our understanding of livestock nutrigenomics is significant. RNA-seq analysis was carried out on total RNA from anterior pituitary of beef cattle followed by water restriction (control, n = 3 and water restriction, n = 3). 14,280 genes were deemed to be expressed (\u3e4 reads per gene per animal), 40 of which were shown to be statistically significantly differentially expressed (SDE) at a false discovery rate (FDR) of 0.1% with a ≥2-fold change between control and water restricted animals. GOseq/ KEGG pathway analysis showed that SDE genes with ≥2- fold change was associated (P \u3c0.05) with one KEGG pathway and six Curated Reactomes pathways associated with G protein-coupled receptor incorporated hormone secretion and transport. Most interestingly, all these pathways were related to Arginine Vasopressin (AVP) which is one of the major regulators of water balance. RNA-seq analysis suggested that, to regulate plasma osmolarity from water restriction, the major changes in anterior pituitary gene expression in water deprivation cattle were related to release of AVP into the circulation and transportation to the kidney where AVP binds to the vasopressin type 2 receptor. This indicates the crucial role of AVP in regulating plasma osmolarity in response to water restriction. This study provides valuable insights into the genomic response of beef cattle to water restriction, highlighting the significance of AVPrelated pathways in maintaining water balance. The findings contribute to advancing our understanding of water requirements in modern livestock and emphasize the need for updated guidelines in the Nutrient Requirements of Beef Cattle. Ultimately, this research can aid in the development of more efficient management strategies to ensure optimal livestock health and productivity in the face of climate variability and limited water availability

Estimating the Effects of Weather, Dry Matter Intake, and Body Weight on Daily Water Intake in Weaned Calves

Objective The purpose of this study was to study the effect of weather, dry matter intake, and body weight on the water requirements of weaned calves and estimating the requirements in a model.Study Description Weaned steers (n=48) were selected to study the effects of the weather, body weight, and dry matter intake on water intake in the winter (n=24) and summer (n=24) months. Calves were provided with ad libitum access to feed and water at the SDSU Cow-Calf Education and Research Facility (CCERF) and measured utilizing an automated feed and water system (Insentec, The Hague, Netherlands). Temperature, humidity, precipitation, wind speed, solar radiation, and air pressure were recorded at a Mesonet automated weather station in Brookings, SD (located 2.4 miles from the SDSU CCERF). Effects of climate data, body weight, and daily dry matter intake on daily water intake will be analyzed utilizing a mixed-effects model