Effect of Dimethylacetamide Concentration on Motility, Quality, Antioxidant Biomarkers, Anti-Freeze Gene Expression, and Fertilizing Ability of Frozen/Thawed Rooster Sperm.

Sperm cryopreservation is of great importance for the poultry industry but still needs to be optimized. The high susceptibility of poultry sperm to cryodamage leads to low fertility rates after cryopreservation. Therefore, the present study aimed at evaluating the effect of including a cryoprotectant, dimethylacetamide (DMA), in the chicken semen freezing extenders at a final concentration of 3%, 6%, or 9% on the post-thawed sperm motility, quality, antioxidant biomarkers, anti-freeze gene expression, and fertilizing ability. Results showed that the total motile sperm, progressivity, and viability were quadratically increased (p < 0.05) in the 6% DMA group. The antioxidant enzyme activity and lipid peroxidation were negatively (p < 0.05) affected by the increase in DMA concentration. Furthermore, some anti-freeze-associated genes such as heat shock protein 70 (HSP70) and ras homolog family member A (RHOA) were linearly and quadratically down-regulated (p < 0.05) with the high concentration of DMA. Finally, the fertility and hatchability rates did not indicate statistical differences between DMA groups. It can be concluded that using the low concentration of 3−6% DMA in the freezing semen extender is preferable to obtain acceptable results in the post-thawed sperm quality and fertility.

Best-fitted regression models for profitability of two egg-type commercial pullets.

This study is focused on describing the most important factors which have a great influence on profitability of egg production of two commercial layer flocks under Egyptian conditions, LSL white and brown. The data for each flock has been collected from seven governorates including the Delta and Upper Egypt zones over the period 2005-2012. General linear procedure was generated to get both least square means and separation of means. Application of stepwise regression was carried to predict the most important factors that affect egg production profitability in US dollar. White egg layers had significantly higher net profit per hen than the brown egg type, being as 12.2 vs. 12.1 cents for the white and brown type egg layers, respectively. Closed houses and battery systems were the preferred systems for the white-egg genotype where pullets achieved significantly higher egg income over feed coast by 15.9 and 14.9 cents for closed and battery system, respectively compared to 10.9 and 11.5 cents for the LSL brown one, respectively. Open houses and floor systems were profitable for brown-egg genotype by recording a significantly higher profitability as 13.3 and 12.7 cents, respectively copmared to 8.7 and 9.7 cents for the white-egg genotype.Both white and brown-egg types had recorded significantly higher net profitability under delta zone rather than upper Egypt by 2.2 cents and 2.1 cents, respectively. Application of the stepwise regression procedure was to predict the net profit (Y) from three independent variables, egg weight (X1), egg price (X2), and hen housed egg production (X3). Generally, LSL white layers, egg price (X2) had the highest share in profitability by 44.24% compared to hen housed egg production (X3) that share 29.98%. For LSL brown layers, egg weight (X1) is the most important factor accounting for the profitability in cents. Its relative importance to the profitability is 57.24% followed by egg price (X2) 21.25%. Hen housed egg production (X3) had very little share 0.14%.

Characterization of Copy Number Variation's Potential Role in Marek's Disease.

Marek's Disease (MD) is a highly contagious pathogenic and oncogenic disease primarily affecting chickens. Chicken Lines 63 and 72, as well as their recombinant congenic strains (RCS) with varied susceptibility to MD, are ideal models to study the complex mechanisms of genetic resistance to MD. In this study, we investigated copy number variation (CNV) in these inbred chicken lines using the Affymetrix Axiom HD 600 K SNP genotyping array. We detected 393 CNV segments across all ten chicken lines, of which 12 CNVs were specifically identified in Line 72. We then assessed genetic structure based on CNV and observed markedly different patterns. Finally, we validated two deletion events in Line 72 and correlated them with genes expression using qPCR and RNA-seq, respectively. Our combined results indicated that these two CNV deletions were likely to contribute to MD susceptibility.

Testis-enriched heat shock protein A2 (HSPA2): Adaptive advantages of the birds with internal testes over the mammals with testicular descent.

The molecular chaperone heat shock protein A2 (HSPA2), a member of the 70 kDa heat shock protein (HSP70) family, plays an important role in spermatogenesis and male fertility. Although HSPA2 is evolutionarily highly conserved across the metazoan lineages, the observation of striking differences in temperature-sensitive expressions, testicular physiology, spermatogenesis, as well as its role in male fertility indicates that avian and mammalian HSPA2 may exhibit distinct evolutionary trajectory. The present study reports that while mammalian HSPA2 is constrained by intense purifying selection, avian HSPA2 has been subjected to positive selection. The majority of the positively selected amino acid residues fall on the α-helix and ß-sheets of the peptide-binding domain located at the carboxyl-terminal region of the avian HSPA2. The detection of positively selected sites at the helix and ß-sheets, which are less tolerant to molecular adaptation, indicates an important functional consequence and contribution to the structural and functional diversification of the avian HSPA2. Collectively, avian HSPA2 may have an adaptive advantage over the mammals in response to heat stress, and therefore, mammals with testicular descent may be at a greater risk in the event of scrotal temperature rise.