Sonika Ahlawat

Melanin is the primary pigment found in the skin, hair, wool and feathers of many vertebrates and plays a crucial role in determining the physical appearance and physiological performance of livestock species. Melanin functions in thermoregulation as well as coloration, photoprotection, and adaptation to diverse environmental conditions. This review examines the biosynthesis of melanin and the genetics of melanogenesis in major livestock species such as cattle, sheep, goats, pigs, horses, and poultry, and the roles of melanin‐based pigmentation within different systems of animal production. The genetic loci ( MC1R, ASIP , TYRP1, TYR, PMEL, MITF, KIT, and others) and polygenic modifiers determine the type and intensity of pigment distribution patterns. Melanin also has a variety of ecological roles, or functions, in addition to economically important traits, affecting adaptation to environmental restraints, product quality, and market preferences. Despite major advances in genomic and transcriptomic studies, many questions still remain, especially in the lack of direct experimental evidence, an insufficient understanding of the physiological roles of melanin in livestock, and a lack of functional validation of key pigmentation genes under production conditions. Future research should focus on bridging these gaps and translating this genetic knowledge to breeding strategies.

Milk protein synthesis in goats is governed by multilevel regulatory mechanisms coordinating genetic, hormonal, nutritional, and cellular signals. Despite growing interest in goat milk proteins due to their distinctive nutritional properties, digestibility, and reduced allergenicity, their regulatory basis remains less characterised than other dairy species. This review integrates current knowledge on goat milk protein composition, genetic polymorphism, and molecular regulation, summarising structural and functional characteristics of caseins, whey proteins, and minor bioactive proteins. It examines how polymorphisms and haplotypes contribute to breed-specific variation in milk yield, composition, and physicochemical properties, highlighting JAK-STAT and mTOR signalling pathways' central roles in integrating hormonal and nutritional signals that control transcription and translation. Evidence from GWAS, QTL analyses, transcriptomics, proteomics, and epigenetic studies outline the genomic architecture and stage-specific regulation of milk protein synthesis, while highlighting knowledge gaps and research opportunities. By integrating genomic, transcriptomic, proteomic, and epigenetic evidence, this review highlights candidate regulatory variants and molecular pathways underlying milk protein synthesis, providing a framework for functional validation, precision breeding, and the development of high-value goat dairy products.

The Changthangi goat, native to the high-altitude Ladakh Plateau in northern India, thrives in oxygen-deficient environments above 4,000 m. This study investigated the genetic basis of high-altitude adaptation in Changthangi goats by integrating comparative genomics and transcriptomics, using the tropical lowland Jamunapari goat as a comparative model. Whole-genome sequence data from 15 individuals per breed were analyzed using complementary selection sweep metrics, including nucleotide diversity, Tajima's D, iHS, CLR, XP-EHH, and FST. These analyses identified candidate genomic regions under strong selective pressure, encompassing genes involved in hypoxia sensing (HIF-1α, HIF-2α/EPAS1, EGLN1), angiogenesis (VEGFA, AGGF1, ZEB1), cardiovascular regulation (PRKCB, ESR1, RYR2), mitochondrial and energy metabolism (ACADSB, ACSS3, ACSL1), cellular stress tolerance (BCL2, ATM), and thermogenesis (UCP1, FGF21). Unlike previous caprine studies that primarily infer hypoxia adaptation from genomic signals alone, our study integrates cardiac transcriptomics to demonstrate that genomic selection in Changthangi goats is accompanied by coordinated transcriptional remodeling across interconnected physiological systems in a physiologically relevant tissue. Comparative cardiac transcriptomic profiling revealed concordant expression divergence in genes associated with oxygen transport, vascular remodeling, mitochondrial function, substrate utilization, redox balance, and genome maintenance. This integrative multi-omics framework provides a mechanistic view of caprine high-altitude adaptation and highlights the value of combining genomic selection analyses with tissue-specific transcriptional profiling to resolve complex adaptive traits.

In poultry, the liver acts as a key site for de novo lipogenesis and plays a central role in controlling fat deposition (P. Wang et al. 2024). Beyond lipid synthesis, it performs essential function...

We designed a genome-wide high-density SNP array using genetically diverse sheep of the Indian subcontinent. The array includes 627 509 biallelic markers and was validated on 522 individuals from diverse breeds of the Indian peninsula. The average call rate for samples passing quality control was 99.6%, with 96.15% (603 523) markers classified as best and recommended. The high-density SNP array offers dense genomic coverage with an average intermarker distance of 4.6 kb, effectively delineates breed-specific clusters and reveals population stratification, underscoring its utility for genetic analysis, selection, and conservation in sheep. This array addresses the limited representation of Asian and African ovine diversity of the commercially available SNP arrays for sheep. Its applicability across global breeds further supports its value in international ovine genomics.