The impact of truncating data on the predictive ability for single‐step genomic best linear unbiased prediction

Simulated and swine industry data sets were utilized to assess the impact of removing older data on the predictive ability of selection candidate estimated breeding values (EBV) when using single‐step genomic best linear unbiased prediction (ssGBLUP). Simulated data included thirty replicates designed to mimic the structure of swine data sets. For the simulated data, varying amounts of data were truncated based on the number of ancestral generations back from the selection candidates. The swine data sets consisted of phenotypic and genotypic records for three traits across two breeds on animals born from 2003 to 2017. Phenotypes and genotypes were iteratively removed 1 year at a time based on the year an animal was born. For the swine data sets, correlations between corrected phenotypes (Cp) and EBV were used to evaluate the predictive ability on young animals born in 2016–2017. In the simulated data set, keeping data two generations back or greater resulted in no statistical difference (p‐value > 0.05) in the reduction in the true breeding value at generation 15 compared to utilizing all available data. Across swine data sets, removing phenotypes from animals born prior to 2011 resulted in a negligible or a slight numerical increase in the correlation between Cp and EBV. Truncating data is a method to alleviate computational issues without negatively impacting the predictive ability of selection candidate EBV.     

Does sand content in spawning substrate result in early larval emergence? Evidence from a lithophilic cyprinid fish

The spawning success of lithophilic salmonids is strongly influenced by the fine sediment content (“fines”) of spawning substrates, yet knowledge on the impacts of fines on the spawning of non‐salmonid lithophiles remains limited, despite their ecological and socio‐economic importance in European rivers. Consequently, the aim here was to use an ex‐situ experiment to investigate the impact of sand content on egg survival and timing of larval emergence of the surface‐spawning cyprinid European barbel Barbus barbus. Thirty incubator boxes within a recirculating system were filled with one of five experimental sediment mixtures (0%–40% sand by mass) that each contained 300 fertilised eggs at a depth of 50 mm. Emerged, free‐swimming larvae were captured and counted daily to assess grain‐size effects on larval survival and emergence. Specifically, total proportion of emerged larvae, cumulative daily proportion of emerged larvae and time required to reach 50% emergence were measured during the study. Whilst the proportion of sand in the sediments did not have a significant impact on egg‐to‐emergence survival (mean survival per treatment 75%–79%), it significantly affected the timing of larval emergence to the water column; early emergence was detected in treatments with elevated sand content (on average, 50% emergence after 12–13 days versus 19 days in the control). Similar to findings from salmonid studies, these results suggest high sand content in spawning gravels can influence timing of larval emergence and potentially cyprinid lithophilic fish survival.     

Evidence for functional G-coupled protein receptors 43 and 120 in subcutaneous and intramuscular adipose tissue of Angus crossbred steers

We conducted 3 independent experiments to demonstrate functional G-coupled protein receptor 43 (GPR43) and GPR120 in bovine intramuscular (i.m.) and subcutaneous (s.c.) adipose tissues. We hypothesized that media volatile fatty acids and long-chain fatty acids would affect cAMP-activated protein kinase-alpha (AMPKα) protein expression and cAMP concentrations differently in i.m. and s.c. adipose tissue. Experiment 1: oleic acid (18:1n-9) decreased phosphorylated AMPKα protein (p-AMPKα) and the p-AMPKα/AMPKα protein ratio in i.m. preadipocytes, increased the p-AMPKα/AMPKα protein ratio in bovine satellite cells, and had no effect in s.c. preadipocytes. Experment 2: ex vivo explants from the 5th to 8th longissimus thoracic rib muscle section of Angus crossbred steers were cultured 48 hr in media containing 0.25 µM ciglitizone, 5 mM glucose, and 5 mM acetate, in the absence or the presence of 100 µM oleic acid. Oleic acid increased acetate incorporation into fatty acids and GPR43 gene expression in i.m. adipose tissue (P < 0.05), but oleic acid had no effect on fatty acid synthesis or GPR43 expression in s.c. adipose tissue. Experiment 3: fresh s.c. and i.m. adipose tissue from the 5th to 8th longissimus thoracic rib muscle section of Angus crossbred steers was transferred immediately to 6-well culture plates containing 3 mL of KHB/Hepes/5 mM glucose. Samples were preincubated with 0.5 mM theophylline plus 10 μM forskolin for 30 min, after which increasing concentrations of acetate or propionate (0, 10⁻³, 10^−2.3, and 10⁻³ M) in the absence or the presence of 100 μM oleic acid or 100 µM palmitic acid (16:0) were added to the incubation media. Acetate had no effect on forskolin-stimulated cAMP production in s.c. adipose tissue but decreased cAMP in i.m. adipose tissue (P < 0.05); this indicates a functional GPR43 receptor in i.m. adipose tissue. The combination of 10⁻² M acetate and oleic acid decrease cAMP production in s.c. adipose tissue, consistent with GPR120 receptor activity, but oleic acid and palmitic acid attenuated the depression of cAMP production caused by acetate in i.m. adipose tissue. Palmitic acid depressed cAMP production in s.c. adipose tissue, and increased cAMP production in i.m. adipose tissue (P < 0.05). Propionate had no effect on cAMP production in s.c. or i.m. adipose tissue. These results provide evidence for functional GPR43 receptors in i.m. adipose tissue and GPR120 receptors in s.c. adipose tissue, both of which would suppress lipolysis.