Sexed semen is semen that has been sorted by its X and Y chromosomes and allows a producer to limit offspring to a single sex as opposed to the near 50/50 natural selection. Sexed semen can achieve 85-90 per cent accuracy of females, suggesting profound implications for the dairy industry in terms of economic returns.

Sexed semen is not new and had been used for over a decade now in the dairy business and has been a successful tool for the dairy farmers, who have been able to grow their herds faster, select females for the herd to maximise the value of each pregnancy, increasing the genetic potential of their herd and helping to improve their bottom line. But there are points that need attention to get a good return on investment such as heat detection and heifer management as well as increase the efficiency of production and increased number of females in herd. Sexed semen can help India do that.

Using Sexed Semen

The process used to sort semen by the gender involves advanced technology and lab work. Individual sperms are treated with dye and then separated based on the presence of the X or Y chromosome. At least 90 per cent of the sperms in each dose of sexed-semen contain the X chromosome (females receive X chromosome from the father, males receive Y chromosome). Using sexed semen instead of conventional semen can increase the average genetic value of the herd simply by creating more heifers over the same period of time.

Figure 1: Sexed semen production system at Select Sires Inc/Sexing Technologies USA. This is a patented process.

A side effect of the sorting process is that the sperms are subject to increased stress. Industry research by reproductive specialists, such as Mel DeJarnette at Select Sires/World Wide Sires, has shown a conception rate for sexed semen at average 75-80 per cent of the rate for conventional semen. Meaning if the conception rate in heifers is 70 per cent using conventional semen, it will be 80 per cent of 70 per cent, that is, 56 per cent in heifers using sexed semen. To maximise the conception rate of sexed semen, it is important to focus on two areas: proper semen handling and selecting the right animals to breed with sexed semen.

Semen Handling

Sexed semen is packaged in 0.25 ml straws, which are more sensitive to temperature changes than 0.5 ml straws. Improper handling of straws can have a negative impact on sperm motility and decrease fertility. These smaller straws are especially sensitive to thermal shock, which can occur through touching the straw with a human hand or thawing at the wrong temperature. To avoid this, frozen semen should be handled with tweezers and thawed at 35o to 37 oC for 45 seconds. The semen should be kept at body temperature (the same range as thawing), either by using an AI syringe warmer or using the breeder’s own body heat, until breeding. Insemination should occur within 5 to 10 minutes of thawing for maximum conception.

Heifer Management

In most of the cases, especially in North America, from where the product originated, sexed semen is recommended for use on virgin heifers, which traditionally have a higher conception rate than milking cows. This is in large part due to the decreased stress that heifers are under, since their bodies are not using energy for milk production. However, heifers may not be the ideal target for every herd.

In USA for breeding Holstein heifers, the goal is set for them to calve at 560 kg body weight. Research has shown that this is the ideal weight to maximise production in the first lactation, and that a heifer weighing less than 400 kg at the time of breeding is at a significant disadvantage because she will have to use more energy during her first lactation to finish growing to her mature body size. This advantage is lost when the heifer weighs more than 680 kg at calving, since overweight heifers tend to have more problems calving and are more susceptible to reproductive and nutritional disorders like fatty liver and ketosis. Under Indian conditions such norms are not worked out as yet

The goal for Holstein heifer nutrition is to reach 330 kg of body weight by 14 months of age. The ideal average Daily Weight Gain (DWG) for heifers in India should be 800 grams. Both of these maximise first lactation production and minimise feeding costs. However, this may not be a reasonable goal for all producers, in which case different breeding strategies may need to be adopted.

Sexed Semen and Cows

Research with beef cattle has shown that sexed semen can achieve similar conception rates in both heifers and lactating cattle under low-stress conditions. For farmers with dual-purpose animals or late maturing heifers, using sexed semen on cows may be the best way to maximise the value of this product. While there are farmers who continue to use sexed semen in selective lactating animals in US also, care should be taken on proper semen handling, breeding techniques including heat detection regardless of the age of the animal. Due to lower conception rates, producers are encouraged to use sexed semen in the most fertile animals.

Economic Value of Using Sexed Semen

A software programme prepared by Dr Victor E Carbera, Associate Professor and Extension Specialist in Dairy Management at the University of Wisconcin (available at can be used to determine the Economic Value of Sexed semen at the farm. In case of low conception rate (30 per cent), the use of sexed semen is not viable.

In case of average conception rate (50 per cent), it is viable to use sexed semen for upto 4 services (the EV of 4th service is though very low). In case of high conception rate (77 per cent), the viability of sexed semen use is good and upto 4 services.

The above working is based on a price of conventional semen at US $12/dose and that of sexed semen at US $36/dose. Cost of raising a calf at US $2.2/day (Rs. 138/day) and the 20 month pregnant heifer is valued at US $1,200 (about Rs. 75,600).

Highly subsidised Indian semen valued at $0.80/dose (Rs.50), the overall economic viability is negative, but if looked at individually, sexed semen could still be used in average conception rate herds for two services and in high conception rate herds, upto 4 services, though the economic viability will be lower for 4th service.

In addition to being financially successful if sexing costs are low enough and fertility is near normal, sexed semen programmes will result in more efficient milk production. Fewer animals will be required per unit of product, making use of this technology ecologically sound. Less feed will be required and less manure will be produced than without sexed semen.