“The most crucial aspect of the artificial insemination cold chain is its reliability (ensuring viability of the sperms from the point of semen extraction to insemination into a female bovine) and reach (to the distant interiors). I am sure this can be of some relevance to the national rollout of the Covid vaccine,” said Rajiv Mitra, CEO of Prabhat Dairy based in Ahmednagar, Maharashtra, which is part of the French Lactalis Group and does roughly 1 lakh artificial inseminations in a year. This dairy, which is part of the French Lactalis Group, does roughly 1 lakh AIs a year.
Since the sperms lose their viability at normal room temperatures within 15 minutes of collection, about 5 ml of semen is first diluted to fill up to 250 ‘straws’, each containing 0.25-0.5 ml solution. These ‘straws’ are then sealed, with details of the donor bull, date of collection etc printed on them, and frozen by immersing in liquid nitrogen containers.
The containers – typically about 35 litres or 48 litres capacity – are then transported from the bull stations to different parts of the country.
“Liquid nitrogen is the most important ingredient in our cold chain. It ensures that the frozen straws are maintained at the required temperature even seconds before being used to inseminate the female animal,” said Dr Ashok Pande, Group Vice President (Scientific Research and Livestock Development) at BAIF Development Research Foundation, Pune.
With 300 active bulls at its two stations at Urulikanchan in Pune district and Dharouli in Jind (Haryana), BAIF produces around 45 lakh ‘semen straws’ every year. That makes it India’s second largest after the National Dairy Development Board, which manages four stations at Bidaj (Gujarat), Salon (Uttar Pradesh), Alamadhi (Tamil Nadu) and Rahuri (Maharashtra) that together supply about 380 lakh ‘straws’ annually.
The artificial insemination is carried out by para-veterinarians, who transfer the ‘semen straws’ into 3-litre containers, thus ensuring easy portability to the interiors.
“The 3-litre container (which has about 720 straws) is the real reason for the success of India’s artificial insemination and cross-breeding programme. Our paravets can carry these containers on two-wheelers, and reach remote villages,” said Pande.
Before insemination, the paravets thaw the frozen semen by using specially-made artificial insemination guns.
The coolant used – liquid nitrogen sourced from chemical fertiliser units or liquid oxygen plants which produce it as a by-product – and machines for filling it into straws are established technologies for dairy farmers.
“Each time the container is opened, liquid nitrogen escapes. We maintain a reserve stock of liquid nitrogen at our centres, from where it can be refilled. The process isn’t very complicated,” said Mitra.
That lack of complication may be of some assurance in the search for viable cold storage solutions for a Covid-19 vaccine.