Effect of thermal conditioning on serum electrolytes, metabolites, corticosterone and expression of CRH gene in selected chicken strains.

Early age thermal conditioning has been found to improve thermotolerance in birds. This study assessed the effect of perinatal thermal conditioning on serum parameters, corticosterone, free fatty acid, globulin and expression of corticotropin-releasing hormone (CRH) gene in five chicken strains; using fifty chicks per strain of Cobb 500 (C500), Ross 308 (R308), Shika Brown (SB), Normal Feathered Nigeria Indigenous (NF) and FUNAAB Alpha (FA). Twenty-five chicks per strain were conditioned at 40 ± 1 °C for 3 h on day 6. On day 10, both conditioned and unconditioned chicks were challenged acutely at 40 ± 1 °C for 15 min, without feed and water. Body weight and feed intake data were collected before and after the heat exposures. Blood samples were collected to determine serum electrolytes, metabolites and corticosterone levels. Brain tissue samples were collected from the 10-day-old conditioned and unconditioned chicks, from which RNA were extracted, synthesized into cDNA and subjected to qPCR. Serum parameters were significantly affected (p < 0.05) by strain, thermal conditioning and their interactions. Calcium and glucose concentrations were highest in NF while FA had highest in sodium. Calcium, glucose and phosphorus were higher in conditioned birds. NF had the highest free fatty acid while FA had the lowest. C500 had the highest globulin levels. Thermal conditioning significantly lowered corticosterone levels in conditioned birds. CRH was shown to be overexpressed in C500. From this research, it can be concluded that early age thermal conditioning affects body temperature regulation in chickens and enhances thermotolerance.

Single nucleotide polymorphisms at heat shock protein 90 gene and their association with thermo-tolerance potential in selected indigenous Nigerian cattle.

Heat shock protein (HSP) 90 gene provides protection and adaptation to thermal assault and certain polymorphisms have been associated to heat tolerance in humans and animals. Single nucleotide polymorphisms (SNPs) of HSP 90 gene were used to evaluate the scientific basis of heat tolerance in four zebu breeds of Nigeria. The DNA was extracted from skin tissue of 90 adult bulls representing White Fulani (WF), Sokoto Gudali (SG), Red Bororo (RB), and Ambala (AM). The SNPs were determined in DNAs using PCR, sequencing, and visualization and bio-editing by chromatogram in SeqMan Ngen tool. Subsequently, respective genotypes were constructed and genotypic and allelic frequencies were computed. Also, body parameters related to heat stress (HS) including body temperature (BT), rectal temperature (RT), and respiratory rates (RR) were taken for each animal before biological sampling and heat tolerance coefficient (HTC) was calculated. We detected four SNPs distinct/specific for each breed as follows: change from thymine (T) to guanine (G) at position 116 (T116G) in RB, G to cytosine (C) at 220 (G220C) in SG, G to adenine (A) at two positions, 346 (G346A) and 390 (G390A) in AM and WF, respectively. Heterozygous SNPs showed significantly lower values (P < 0.0001) for BT, RT, RR, and HTC than homozygous genotypes at all positions. We hypothesize that animals with heterozygous SNPs in exon 3 of HSP 90 may be tolerant to HS. These SNPs can be used as bio-markers for screening large populations of cattle for tolerance to hot tropical conditions in Nigeria and other sub-humid places.

Mitochondrial DNA sequence analyses and phylogenetic relationships among two Nigerian goat breeds and the South African Kalahari Red.

The first hypervariable (HV1) region of mitochondrial DNA (mtDNA) of two popular Nigerian goat breeds: West African Dwarf (WAD) (n=35) and Red Sokoto (RS) (n=37) and one exotic breed: Kalahari Red (KR) (n=38) imported from South Africa were sequenced to investigate sequence diversity, genetic structure, origin, and demographic history of the populations. A total of 68 polymorphic sites were found in 110 sequences that grouped into 68 haplotypes. Average haplotype and nucleotide diversities for all breeds were 0.982±0.005 and 0.02350±0.00213, respectively. Phylogenetic analysis revealed two mtDNA lineages (A and B). Lineage A was predominant and included all haplotypes from WAD and RS and 5 out of 11 haplotypes of KR goats. The remaining haplotypes (6) of KR belong to lineage B. The analysis of molecular variance revealed a high-within breed genetic variance of 82.4% and a low-between breed genetic variance of 17.6%. The three breeds clustered with Capra aegagrus as their wild ancestor. Mismatch distribution analysis showed that WAD, RS and haplogroup A have experienced population expansion events. The study has revealed very high diversity within the three breeds which are not strongly separated from each other based on mtDNA analysis. The information obtained on the genetic structure of the breeds will be useful in planning improvement and conservation programs for the local populations.