Estimating genetic parameters for growth traits is crucial to plan breeding strategies for improving meat production in indigenous sheep breeds. The study first tested the effects of environmental and maternal effects on five growth traits, including birth weight (BWT), weight at 120 days (WT120), weight at 180 days (WT180), weight at 270 days (WT270) and weight at 365 days of age (WT365) and then estimated genetic parameters for these traits using data obtained in 1215 Lohi sheep. The effects of factors, including year (YOB), season (SOB) and type of birth (TOB), age of dam (AOD) and sex on growth traits of Lohi sheep, were examined using analysis of variance (ANOVA) in R software. Sex, TOB and YOB significantly affected all studied traits. The estimates of direct and maternal heritability for BWT and WT120 were 0.15 ± 0.08 and 0.20 ± 0.06, and 0.45 ± 0.16, 0.21 ± 0.08, respectively. The direct heritability estimates for WT180, WT270 and WT365 were 0.20 ± 0.07, 0.21 ± 0.07 and 0.19 ± 0.08, respectively. Due to the high heritability estimate obtained for WT120 compared to other studied traits, and its strong genetic correlation (>0.9) with post-weaning growth traits, it is recommended that selection must be practiced on WT120 to improve the growth performance of Lohi sheep. The results could be used for the development of genetic/genomic selection programs aiming to improve the production performance of the Lohi sheep.

Background: Both heart failure (HF) with preserved ejection fraction (HFpEF) and heart failure with reduced ejection fraction (HFrEF) can present a wide variety of cardiac morphologies consequent to cardiac remodeling. We sought to study if geometric changes to the heart during such remodeling will adversely affect the ejection fraction (EF) parameter’s ability to serve as an indicator of heart function, and to identify the mechanism for it.Methods and Results: A numerical model that simulated the conversion of myocardial strain to stroke volume was developed from two porcine animal models of heart failure. Hypertrophic wall thickening was found to elevate EF, while left ventricle (LV) dilation was found to depress EF when myocardial strain was kept constant, causing EF to inaccurately represent the overall strain function. This was caused by EF being calculated using the endocardial boundary rather than the mid-wall layer. Radial displacement of the endocardial boundary resulted in endocardial strain deviating from the overall LV strain, and this deviation varied with LV geometric changes. This suggested that using the epi- or endo-boundaries to calculate functional parameters was not effective, and explained why EF could be adversely affected by geometric changes. Further, when EF was modified by calculating it at the mid-wall layer instead of at the endocardium, this shortcoming was resolved, and the mid-wall EF could differentiate between healthy and HFpEF subjects in our animal models, while the traditional EF could not.Conclusion: We presented the mechanism to explain why EF can no longer effectively indicate cardiac function during cardiac geometric changes relevant to HF remodeling, losing the ability to distinguish between hypertrophic diseased hearts from healthy hearts. Measuring EF at the mid-wall location rather than endocardium can avoid the shortcoming and better represent the cardiac strain function.

The aim of this investigation was to find single nucleotide polymorphisms (SNPs) in the myostatin (MSTN) and the beta-3 adrenergic receptor (ADRB3) genes associated with growth and ultrasound carcass traits in Kajli sheep. The five growth traits were birth weight (BWT-EBV), 120-day weight (120DWT-EBV), 180-day weight (180DWT-EBV), 270-day weight (270DWT-EBV), and 365-day weight (365DWT-EBV). The three ultrasound carcass traits were width (WLD) and depth of longissimus dorsi (DLD) and back fat thickness (BFT). The analysis of the MSTN sequence revealed one non-synonymous substitution (c.197T > A) in exon 1, one single nucleotide substitution (c.373 + 18G > T) in intron 1, and one synonymous substitution (c.861T > A) in exon 3. However, there were four single nucleotide synonymous substitutions (c.130C > T, c.294C > G, c.579G > T, and c.654C > G) in exon 1 of the ADRB3 gene. All the SNPs in the MSTN gene, except for c.373 + 18G > T, were in Hardy-Weinberg Equilibrium (HWE). Conversely, none of the SNPs found in ADRB3 were in HWE. Two of the MSTN SNPs (c.197T > A and c.373 + 18G > T) had significant associations with all evaluated growth and ultrasound carcass traits. The SNPs c.130C > T and c.294C > G in ADRB3 were significantly associated with 180DWT-EBV. Collectively, these findings indicate that several SNPs in the studied genes were significantly related to growth and carcass traits in Kajli sheep.