Review: Research Progress of Dairy Sheep Milk Genes

Abstract

The dairy sheep industry is an important but lacking part of the small ruminant industry. For a sheep breeding program, in addition to wool and meat use, sheep milk can also be processed into high-end dairy products such as cheese and milk powder and bring high economic interests for businesses home and abroad. With increasing interest in sheep milk, the content of which is becoming increasingly clearer, people have found that the nutritional value of sheep milk is higher than that of goat milk and cow milk, with abundant fat yield, protein percentage, and mineral contents, which provide a good opportunity for the development of the sheep milk industry. This review will introduce some dairy sheep breeds with the highest milk production worldwide and compare sheep milk nutrition contents with other ruminants’ milk. Moreover, genes influencing lactation or mammary gland growth like CSN2, SLC2A2, SCD, and SOCS2, which have been revealed in recent studies to significantly affect milk production and milk composition traits will be discussed. For the SLC2A2 gene, working as an important solute carrier to transport small molecular nutrition from blood to milk and SOCS2 gene mutation as an indicator of mastitis, in addition, other genes have been detected that correlate with milk traits, which will be introduced in the review. Some personal opinions into future sheep milk development will be given in the final part of the text. Although the research of sheep milk genetic factors has achieved some progress in recent years, there is still a long way to go.

Polymorphisms of ITGA9 Gene and Their Correlation with Milk Quality Traits in Yak (Bos grunniens)

“…The FADS2 gene may have an effect on milk fatty acid composition by influencing liver metabolism [ 40 ]. The SLC2A2 gene affects milk quality by influencing the transfer of nutrients from the blood to the emulsion [ 41 ]. There is an increasing number of studies using SNP loci to explore genetic effects affecting milk quality, but further development is needed in yaks.…”

Identification of Genetic Polymorphisms of PI, PIII, and Exon 53 in the Acetyl-CoA Carboxylase-α (ACACα) Gene and Their Association with Milk Composition Traits of Najdi Sheep

“…In contrast, the FASN, ACAC, and SCD polymorphisms are key genes affecting PUFA composition and are promising for improving FA composition [ 34 , 35 ]. Most of the previously reported candidate genes show strong effects on milk traits, but the mechanisms by which these genes control milk quantity or composition have yet to be investigated [ 36 ].…”

Phenotypic characteristics and factors associated with Assaf lamb body weight and morphology

“…Assaf sheep is a dual-purpose breed used for both meat and milk production; but primarily for milk production (Albaqain et al, 2010). It is a crossbreed of Awassi and East Friesian breeds, consisting of 5/8 Awassi and 3/8 East Friesian sheep (Eyal et al, 1986;Li et al, 2022). Assaf sheep showed higher fertility and milk production than Awassi sheep (Ahmad and Abdallah, 2013).…”