6-4.4.2.2 Lactation:

Dairy farming is an attractive field in agriculture which has huge commercial potential. Transgenic mice models have been developed to demonstrate the feasibility of such modifications in larger animals but further research is required to develop the concept. Production of milk having modified properties like lactose free milk, modified lipid content etc would have a niche market. Transgenic goat has been developed to secret spider silk in goat milk.

6-4.4.2.3Wool production:

Transgenic sheep has been developed to increase wool production (~6.2% increase) by introducing “keratin-IGF-I” construct. Such modification showed no adverse effect on the growth and development of the transgenic animals.

6-4.4.2.4Eco-friendly farm animals:

The high phosphorous content in manure of farm animals causes environmental pollution. Transgenic pigs have been developed bearing a bacterial “phytase” gene which allow digestion of plant phytate. Transgenic pigs showed ~75% lesser fecal phosphate output compared to the wildtype pigs.

6-4.5 ATryn® -First Recombinant Human Antithrombin:

The first product derived from a transgenic animal is a recombinant antithrombin called ATryn® was developed by GTC Biotherapeutics and approved by US Food and Drug Administration (FDA) in 2009. It is used for the prophylactic treatment of deep vein thrombosis in patients with hereditary antithrombin deficiencies. The promoter region from goat beta-casein gene was linked to human antithrombin (hAT) cDNA and the recombinant construct containing the transgene was introduced into the goat embryos, which were then implanted into surrogate mothers. The resulting offsprings carrying this transgene produced the recombinant human antithrombin (rhAT) in their milk. The rhAT protein is isolated from the milk by conventional purification method using tangential flow filtration, anion exchange chromatography, heparin affinity chromatography, nanofiltration and hydrophobic interaction chromatography with a yield of greater than 50%.