Genome-wide association study for carcass weight in pasture-finished beef cattle in Hawai'i.

Introduction: Genome-wide association studies (GWAS) have identified genetic markers for cattle production and reproduction traits. Several publications have reported Single Nucleotide Polymorphisms (SNPs) for carcass-related traits in cattle, but these studies were rarely conducted in pasture-finished beef cattle. Hawai'i, however, has a diverse climate, and 100% of its beef cattle are pasture-fed. Methods: Blood samples were collected from 400 cattle raised in Hawai'i islands at the commercial harvest facility. Genomic DNA was isolated, and 352 high-quality samples were genotyped using the Neogen GGP Bovine 100 K BeadChip. SNPs that did not meet the quality control standards were removed using PLINK 1.9, and 85 k high-quality SNPs from 351 cattle were used for association mapping with carcass weight using GAPIT (Version 3.0) in R 4.2. Four models were used for the GWAS analysis: General Linear Model (GLM), the Mixed Linear Model (MLM), the Fixed and Random Model Circulating Probability Unification (FarmCPU), the Bayesian-Information and Linkage-Disequilibrium Iteratively Nested Keyway (BLINK). Results and Discussion: Our results indicated that the two multi-locus models, FarmCPU and BLINK, outperformed single-locus models, GLM and MLM, in beef herds in this study. Specifically, five significant SNPs were identified using FarmCPU, while BLINK and GLM each identified the other three. Also, three of these eleven SNPs ("BTA-40510-no-rs", "BovineHD1400006853", and "BovineHD2100020346") were shared by multiple models. The significant SNPs were mapped to genes such as EIF5, RGS20, TCEA1, LYPLA1, and MRPL15, which were previously reported to be associated with carcass-related traits, growth, and feed intake in several tropical cattle breeds. This confirms that the genes identified in this study could be candidate genes for carcass weight in pasture-fed beef cattle and can be selected for further breeding programs to improve the carcass yield and productivity of pasture-finished beef cattle in Hawai'i and beyond.

Climate change impacts shifting landscape of the dairy industry in Hawai'i.

Proper knowledge and understanding of climatic variability across different seasons are important in farm management. To learn more about the potential effects of climate change on dairying in Hawaii, we conducted a study on site-specific climate characterization using several variables including rainfall, wind speed (WS), solar radiation, and temperature, at two dairy farms located on Hawai`i Island, Hawai`i, in Ookala named "OK DAIRY" and in Upolu Point named "UP DAIRY." Temperature-humidity index (THI) and WS variations in the hottest four months (June to September) were analyzed to determine when critical thresholds that affect animal health are exceeded. Rainfall data were used to estimate the capacity of forage production in 6-mo wet (November to April) and dry (May to October) seasons. Future projections of temperature and rainfall were assessed using mid- and end-century gridded data products for low (RCP 4.5) and high emissions (RCP 8.5) scenarios. Our results showed that the "OK DAIRY" site received higher rainfall than the "UP DAIRY" site, favoring grass growth and forage availability. In addition, the "UP DAIRY" site was more stressful for animals during the summer (THI 69 to 73) than the "OK DAIRY" site (THI 67 to 70) as the THI exceeded the critical threshold of 68, which is conducive for high-lactating cattle. On the "UP DAIRY" site, the THI did not drop below 68 during the summer nights, which created fewer opportunities for cattle to recover from heat stress. Future projections indicated that air temperature would increase 1.3 to 1.8 °C by mid-century and 1.6 to 3.2 °C by the end-century at both farms, and rainfall will increase at the "OK DAIRY" site and decrease at the "UP DAIRY" site by the end-century. The agriculture and livestock industries, particularly the dairy and beef subsectors in Hawai`i, are vulnerable to climate changes as higher temperatures and less rainfall will have adverse effects on cattle. The findings in this study demonstrated how both observed and projected changes in climate support the development of long-term strategies for breeding and holistic livestock management practices to adapt to changing climate conditions.

Exocyst components promote an incompatible interaction between Glycine max (soybean) and Heterodera glycines (the soybean cyst nematode).

Vesicle and target membrane fusion involves tethering, docking and fusion. The GTPase SECRETORY4 (SEC4) positions the exocyst complex during vesicle membrane tethering, facilitating docking and fusion. Glycine max (soybean) Sec4 functions in the root during its defense against the parasitic nematode Heterodera glycines as it attempts to develop a multinucleate nurse cell (syncytium) serving to nourish the nematode over its 30-day life cycle. Results indicate that other tethering proteins are also important for defense. The G. max exocyst is encoded by 61 genes: 5 EXOC1 (Sec3), 2 EXOC2 (Sec5), 5 EXOC3 (Sec6), 2 EXOC4 (Sec8), 2 EXOC5 (Sec10) 6 EXOC6 (Sec15), 31 EXOC7 (Exo70) and 8 EXOC8 (Exo84) genes. At least one member of each gene family is expressed within the syncytium during the defense response. Syncytium-expressed exocyst genes function in defense while some are under transcriptional regulation by mitogen-activated protein kinases (MAPKs). The exocyst component EXOC7-H4-1 is not expressed within the syncytium but functions in defense and is under MAPK regulation. The tethering stage of vesicle transport has been demonstrated to play an important role in defense in the G. max-H. glycines pathosystem, with some of the spatially and temporally regulated exocyst components under transcriptional control by MAPKs.