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How technology can deliver freedom from male calf

Sexed semen technology is about preselecting the sex of offspring by sorting or separating the X-sperms from Y-sperms. The aim is to deliver freedom from male calves, by ensuring that cows are inseminated by semen containing only X-chromosome-bearing sperms.

Written by Harish Damodaran |
Updated: August 16, 2017 2:21:25 pm
sexed semen, sexed female calf semen, indian dairy farming, indian dairy farmer, gaurakshak activism, cow protection, buffalloes male calf, bill sperm, sperm modulation, sexing technologies, indian express news, india news A farmer in a village near Anand, Gujarat, feeding his young calf. Express photo by Bhupendra Rana

In these times of gaurakshak activism, there can be nothing worse for dairy farmers than their cows or buffaloes delivering male calves. Fortunately, technology is now available to address the problem to an extent — in the form of ‘sexed semen’ having 90%-plus sperms carrying the X-chromosome, and capable of producing only female offspring.

A bull’s sperm has 30 chromosomes, including one which is either an X- or a Y-chromosome whose genes code for sex. The egg of a cow, too, contains 30 chromosomes, one of which is, however, always an X-chromosome (just as the human sperm and egg have 23 chromosomes each, one of them either an X- or a Y-chromosome in the case of the former, and one only an X-chromosome for the latter).
When a sperm and egg unite, and the former carries the X-chromosome, the resultant offspring is female (XX). When a Y-chromosome-bearing sperm fertilises an egg, the result is a male calf (XY).

Sexed semen technology is about preselecting the sex of offspring by sorting or separating the X-sperms from Y-sperms. The aim is to deliver freedom from male calves, by ensuring that cows are inseminated by semen containing only X-chromosome-bearing sperms. The sorting process basically involves exploiting the differences in deoxyribonucleic acid (DNA) content between X-chromosome-bearing and Y-chromosome-bearing sperms. The former contains slightly more DNA, with the difference ranging from 3.6% to 4.2%, depending upon the breed of the cattle or buffalo.

In 2004, a Texas-based company, Sexing Technologies (ST), commercialised sexed semen production using a procedure to stain the sperm cells with a fluorescent dye that binds to their DNA. The dyed cells are made to pass through a laser beam from a machine (flow cytometer) that can sort the sperms based on the amount of fluorescent light they give off. As the X-chromosome-bearing sperms contain more DNA, these cells absorb more dye and emit more light. That, then, allows for separation of the X- and Y- sperm fractions in the semen.

ST’s sperm-sorting technology is claimed to be 93% accurate. Thus, if a cow is inseminated using such sexed semen, there is a 93% chance that the calf produced will be female. With ordinary semen used in artificial insemination (AI), that probability is 50-50.

Sexed semen’s usefulness is obvious, particularly in a country where even male calves cannot be sent freely to the slaughterhouse. That freedom has been further curtailed in a regime of empowered gaurakshaks on the prowl. If a cow after insemination and 9-10 months of pregnancy produces a male calf, the loser is the farmer who will have to rear an animal that’s not going to yield him either milk or an income. Worse, he can’t be sure that the same cow 13-14 months down the line — assuming 3-4 months of post partum rest and 9-10 months’ pregnancy — will deliver a female calf.

But the issue here is cost, which, for AI using conventional semen frozen in 0.25-ml vials (‘straws’), is just over Rs 50 per insemination dose. The comparable cost of sexed semen to the farmer is now anywhere between Rs 1,200 and Rs 2,600 per straw.

“Semen cost goes up if it is from a bull with higher genetic merit (evaluated in terms of milk yields, number of productive lactations, fat and protein content, etc.) that can also be transmitted to the progeny,” notes Daljeet Singh, president of the Progressive Dairy Farmers’ Association (PDFA) of Punjab, which annually imports 15,000-20,000 frozen sexed semen doses on behalf of its members. The semen is sourced from bovine genetics firms such as World Wide Sires, Genex and ABS Global of US, and Semex of Canada.

The high cost is due to two main reasons.

The first is the virtual monopoly over knowhow. Sexed semen — even that supplied by global animal genetics majors — is produced from raw ejaculate, largely using ST’s proprietary sperm-sorting technology. The parallel one could cite is the near-stranglehold enjoyed by Monsanto vis-à-vis Bt cotton.

Secondly, the sexed semen currently being used by farmers like those affiliated to PDFA is entirely imported, and based on 100% Holstein Friesian (HF) or Jersey bulls. Semen imports are, moreover, subject to cumbersome procedures entailing approvals from the Directorate General of Foreign Trade and animal husbandry departments, both at the Centre and state levels.

There have been some recent encouraging developments, though, on both counts. In April, ABS Global was granted an injunction by a US court against ST, after the latter was found to have “wilfully maintained monopoly power” in the market for sexed bovine semen processing. It paved the way for ABS to commercially launch its own Genus Sexed Semen technology, which the Wisconsin-headquartered firm plans to introduce worldwide, including in India.

“Indian farmers at present have access only to imported sexed semen from HF and Jersey bulls abroad. From September 1, we will offer them sexed semen also from local HF-Sahiwal and HF-Gir crossbreds; 100% indigenous Sahiwal, Gir and Red Sindhi bulls; and pure Murrah buffaloes. Since the semen is being processed domestically, the cost would be half that of the imported sexed material,” says Arvind Gautam, managing director of ABS India, which has a stud farm facility at Bhilwadi in Sangli (Maharashtra), housing over 100 bulls with annual semen production capacity of 70 lakh straws.

R G Chandramogan, chairman of Chennai-based Hatsun Agro Product Ltd — India’s biggest private sector dairy that undertakes 5.5 lakh-odd AIs a year — believes the domestic market is large enough for sexed semen to be made available at well below Rs 500 per straw.

In 2015-16, about 670 lakh AIs were carried out in India, covering an estimated 30% of its breedable cows and buffaloes. “No country will give you this kind of volumes for sexed semen, even if fewer AIs are required to produce the same number of female calves,” points out Chandramogan.

But pricing is only one part. The conception rate — chances of the animal getting pregnant — from sexed semen is 10-20% lower compared to conventional semen. The reason for it is lower sperm count (machine sorting speeds and efficiency aren’t high enough) and possibility of damage to the cells during the sorting process (from staining with dye, exposure to laser light beam, etc.).

As a result, sexed semen is more effective in inseminating young heifers and cows that have calved only once. The older animals may require more AIs relative to insemination done using normal semen. That raises costs further, even if there a greater likelihood of a female calf getting delivered.

But for all its drawbacks, this is a technology still evolving and destined for improvement. ABS claims its new product is gentler on the sperm cells, with lower processing pressures. There is no doubting sexed semen’s utility to the Indian dairy farmer today — with or without the gaurakshak.

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