Is sexed semen the answer? The answer to what exactly? Most countries that use sexed semen do so to generate more female calves from their high-performing cows. Advances in sexing technology have helped to narrow the gap in conception rates between sexed and conventional semen. Sexing Technologies, which sorts the straws, claims that conception rates with Sexed Ultra 4M are approaching that of conventional semen. So far so good.
Things came to a head last year when the supply of male calves increased due to herd expansion
However, in Ireland, the issue is not insufficient numbers of high-genetic merit female calves – most farms can generate surplus high-EBI female calves easily enough. Instead, the issue in Ireland is the bull calf. Things came to a head last year when the supply of male calves increased due to herd expansion while at the same time demand for male calves from beef farmers decreased due to very low beef prices and uncertainty around Brexit.
This led to a drop in the price of calves and buyers also became choosier about the type of calf that they wanted. Calves with a low beef merit were harder to shift. This led to a concern about calf welfare.
In light of the price and demand disparity, farmers were encouraged to breed calves with higher beef merit
However, when the dust settled on spring 2019, the concerns about calf welfare were, thankfully, unfounded. Calf mortality rates from the dairy herd for 2019 were only 4.5%, including calves dead at birth and mortality after calves were sold from dairy farms. This is very low by all international standards.
In light of the price and demand disparity, farmers were encouraged to breed calves with higher beef merit. This was the clear message from the IFA-organised calf welfare meetings last autumn. Sexed semen was suggested as a way of achieving this; use less dairy semen and more beef semen. Problem solved. Or is it?
In New Zealand, an LIC trial on frozen sexed semen found that conception rates decreased by 13% compared with conventional semen
Teagasc studies conducted in 2018 and 2019 on Sexed Ultra 4M sexed semen on commercial farms found that the conception rate was reduced when sexed semen was used. On average over the two years, the conception rate with sexed semen was 50%, while it was 61% with conventional semen – an 18% drop. In New Zealand, an LIC trial on frozen sexed semen found that conception rates decreased by 13% compared with conventional semen.
For whatever reason, it appears that sexed semen results are poorer on grass-based and block-calving systems, compared to confinement and all year round calving systems. The drop in conception rate represents a big cost at farm level. In effect, using sexed semen across a herd would undo a lot of the fertility gains brought about by EBI over the last 20 years as it would lead to a more spread out calving pattern.
Variability
However, while the trial results show a reduction in conception rate to sexed semen, there were herds in the Teagasc study that got on well – on a par or, in some cases, even better than conventional semen. This indicates that there are other factors at play.
Best results seem to be obtained when the sexed semen straw is handled exactly as per protocol
At present, these factors seem to be related to semen handling, cow fertility and timing of AI.
Best results seem to be obtained when the sexed semen straw is handled exactly as per protocol, the cow has had a number of cycles since calving and is in good body condition score with no health problems. The Teagasc guidelines for sexed semen are as follows;
Only use in the first 10 days of the breeding season, (to limit the effect of poor conception rates).Only use on cows calved more than 50 days and have been cycling.Only use on cows that had an easy calving and have no uterine infections.Do not use on cows that are lame, have mastitis or other health issues. In all cases, later than normal insemination is advised when using sexed semen. Teagasc recommends that animals should be inseminated 14 to 20 hours after the onset of heat. This means that if using once-a-day AI or even twice-a-day AI, it will not be possible to serve all animals that come into heat with sexed semen, even if they fulfil the criteria outlined above.
At a practical level, this more or less rules out using sexed semen in the evening time, presuming that the cows for AI in the evening were the ones first observed in heat at the morning milking.
The reason for this is that the window is too short. For example, if a cow was first observed in heat while bringing in the cows at 7am, that cow should not be inseminated until 9pm that night at the earliest. Regardless of whether DIY AI or a technician service is employed, that’s just not practical.
According to Teagasc research, 70% of heats are displayed between 9pm and 7am which rules out a very significant proportion of the herd for sexed semen straight away
Of course, it is possible that the cow started bulling at say, midnight, but we can’t tell for sure unless the cow is fitted with expensive automated heat detection aids. However, if a cow was observed in heat while bringing in the cows at 4pm for the evening milking, she would be an ideal candidate for sexed semen anytime between 6am and 12pm the following morning.
According to Teagasc research, 70% of heats are displayed between 9pm and 7am which rules out a very significant proportion of the herd for sexed semen straight away. So for all the reasons outlined, it is not practical nor advisable to use only sexed semen. It must be used in conjunction with either conventional dairy or beef AI in order to avoid a big drop in conception rates. It goes without saying that the straw needs to be handled carefully.
There are a lot less viable sperm cells in a straw of sexed semen compared with a straw of conventional semen. So while there is some tolerance for deviation from standards with conventional straws, there is no tolerance with sexed straws.
According to Stephen Butler from Teagasc, there is no issue with using sexed semen in association with a synchrony programme
The same rules around timing of insemination apply to heifers, but the conception rates with heifers are generally higher than that of cows. Thus, conception rates with sexed semen should be higher also. According to Stephen Butler from Teagasc, there is no issue with using sexed semen in association with a synchrony programme such as PG or CIDR-based synchronisation.
As outlined in Table 1, a farmer milking 100 cows, bringing in 20 replacement heifers each year and using only sexed dairy AI, will struggle to have 18 dairy heifer calves on the ground after all cows are calved.
This is after you account for submission rates, cows coming into heat outside the correct window, conception rates and heifer calf rates with sexed semen. Eighteen heifer calves is close to the target of 20, so it shows it can be done.
However, the question is, why would you do it? Considerably more heifer calves would be generated if conventional semen was used for the first three weeks.
The cows that don’t get dairy semen could get served to higher-value beef bulls.
But, remember, the Teagasc trial at Derrypatrick has shown that high-EBI Holstein Friesian bulls outperform native beef breeds in terms of physical and financial performance.
Calves from heifers tend to be small anyway, so if they are mostly female then those calves won’t go into the beef sector
Where sexed semen has more of a role is in heifers. For one thing, the timing of insemination is more flexible as you are not confined to milking times. Secondly, the conception rate with heifers should be higher. Finally, calves from heifers tend to be small anyway, so if they are mostly female then those calves won’t go into the beef sector.
In my view, farmers need to be wary about using sexed semen in high levels across their cow herd. There would need to be a better reason to use it than currently exists. It is a more viable option for use on heifers.
Read more
Sexing is the future - or is it?
Surge in sexed semen use in dairy herds
Is sexed semen the answer? The answer to what exactly? Most countries that use sexed semen do so to generate more female calves from their high-performing cows. Advances in sexing technology have helped to narrow the gap in conception rates between sexed and conventional semen. Sexing Technologies, which sorts the straws, claims that conception rates with Sexed Ultra 4M are approaching that of conventional semen. So far so good.
Things came to a head last year when the supply of male calves increased due to herd expansion
However, in Ireland, the issue is not insufficient numbers of high-genetic merit female calves – most farms can generate surplus high-EBI female calves easily enough. Instead, the issue in Ireland is the bull calf. Things came to a head last year when the supply of male calves increased due to herd expansion while at the same time demand for male calves from beef farmers decreased due to very low beef prices and uncertainty around Brexit.
This led to a drop in the price of calves and buyers also became choosier about the type of calf that they wanted. Calves with a low beef merit were harder to shift. This led to a concern about calf welfare.
In light of the price and demand disparity, farmers were encouraged to breed calves with higher beef merit
However, when the dust settled on spring 2019, the concerns about calf welfare were, thankfully, unfounded. Calf mortality rates from the dairy herd for 2019 were only 4.5%, including calves dead at birth and mortality after calves were sold from dairy farms. This is very low by all international standards.
In light of the price and demand disparity, farmers were encouraged to breed calves with higher beef merit. This was the clear message from the IFA-organised calf welfare meetings last autumn. Sexed semen was suggested as a way of achieving this; use less dairy semen and more beef semen. Problem solved. Or is it?
In New Zealand, an LIC trial on frozen sexed semen found that conception rates decreased by 13% compared with conventional semen
Teagasc studies conducted in 2018 and 2019 on Sexed Ultra 4M sexed semen on commercial farms found that the conception rate was reduced when sexed semen was used. On average over the two years, the conception rate with sexed semen was 50%, while it was 61% with conventional semen – an 18% drop. In New Zealand, an LIC trial on frozen sexed semen found that conception rates decreased by 13% compared with conventional semen.
For whatever reason, it appears that sexed semen results are poorer on grass-based and block-calving systems, compared to confinement and all year round calving systems. The drop in conception rate represents a big cost at farm level. In effect, using sexed semen across a herd would undo a lot of the fertility gains brought about by EBI over the last 20 years as it would lead to a more spread out calving pattern.
Variability
However, while the trial results show a reduction in conception rate to sexed semen, there were herds in the Teagasc study that got on well – on a par or, in some cases, even better than conventional semen. This indicates that there are other factors at play.
Best results seem to be obtained when the sexed semen straw is handled exactly as per protocol
At present, these factors seem to be related to semen handling, cow fertility and timing of AI.
Best results seem to be obtained when the sexed semen straw is handled exactly as per protocol, the cow has had a number of cycles since calving and is in good body condition score with no health problems. The Teagasc guidelines for sexed semen are as follows;
Only use in the first 10 days of the breeding season, (to limit the effect of poor conception rates).Only use on cows calved more than 50 days and have been cycling.Only use on cows that had an easy calving and have no uterine infections.Do not use on cows that are lame, have mastitis or other health issues. In all cases, later than normal insemination is advised when using sexed semen. Teagasc recommends that animals should be inseminated 14 to 20 hours after the onset of heat. This means that if using once-a-day AI or even twice-a-day AI, it will not be possible to serve all animals that come into heat with sexed semen, even if they fulfil the criteria outlined above.
At a practical level, this more or less rules out using sexed semen in the evening time, presuming that the cows for AI in the evening were the ones first observed in heat at the morning milking.
The reason for this is that the window is too short. For example, if a cow was first observed in heat while bringing in the cows at 7am, that cow should not be inseminated until 9pm that night at the earliest. Regardless of whether DIY AI or a technician service is employed, that’s just not practical.
According to Teagasc research, 70% of heats are displayed between 9pm and 7am which rules out a very significant proportion of the herd for sexed semen straight away
Of course, it is possible that the cow started bulling at say, midnight, but we can’t tell for sure unless the cow is fitted with expensive automated heat detection aids. However, if a cow was observed in heat while bringing in the cows at 4pm for the evening milking, she would be an ideal candidate for sexed semen anytime between 6am and 12pm the following morning.
According to Teagasc research, 70% of heats are displayed between 9pm and 7am which rules out a very significant proportion of the herd for sexed semen straight away. So for all the reasons outlined, it is not practical nor advisable to use only sexed semen. It must be used in conjunction with either conventional dairy or beef AI in order to avoid a big drop in conception rates. It goes without saying that the straw needs to be handled carefully.
There are a lot less viable sperm cells in a straw of sexed semen compared with a straw of conventional semen. So while there is some tolerance for deviation from standards with conventional straws, there is no tolerance with sexed straws.
According to Stephen Butler from Teagasc, there is no issue with using sexed semen in association with a synchrony programme
The same rules around timing of insemination apply to heifers, but the conception rates with heifers are generally higher than that of cows. Thus, conception rates with sexed semen should be higher also. According to Stephen Butler from Teagasc, there is no issue with using sexed semen in association with a synchrony programme such as PG or CIDR-based synchronisation.
As outlined in Table 1, a farmer milking 100 cows, bringing in 20 replacement heifers each year and using only sexed dairy AI, will struggle to have 18 dairy heifer calves on the ground after all cows are calved.
This is after you account for submission rates, cows coming into heat outside the correct window, conception rates and heifer calf rates with sexed semen. Eighteen heifer calves is close to the target of 20, so it shows it can be done.
However, the question is, why would you do it? Considerably more heifer calves would be generated if conventional semen was used for the first three weeks.
The cows that don’t get dairy semen could get served to higher-value beef bulls.
But, remember, the Teagasc trial at Derrypatrick has shown that high-EBI Holstein Friesian bulls outperform native beef breeds in terms of physical and financial performance.
Calves from heifers tend to be small anyway, so if they are mostly female then those calves won’t go into the beef sector
Where sexed semen has more of a role is in heifers. For one thing, the timing of insemination is more flexible as you are not confined to milking times. Secondly, the conception rate with heifers should be higher. Finally, calves from heifers tend to be small anyway, so if they are mostly female then those calves won’t go into the beef sector.
In my view, farmers need to be wary about using sexed semen in high levels across their cow herd. There would need to be a better reason to use it than currently exists. It is a more viable option for use on heifers.
Read more
Sexing is the future - or is it?
Surge in sexed semen use in dairy herds
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