The first question autumn-calving, or liquid milk, farmers should ask themselves is when to calve
Finding the correct calving date will inform the correct mating start date as it is 282 days prior to calving. The correct calving date comes down to the principles and objectives of the farm and the system.
In Ireland, producing milk over the winter without a bonus is a very costly exercise with very little margin. Therefore, only farms with a liquid or a winter milk contract or those guaranteed a bonus for all milk produced over the winter should calve cows in the autumn. Those that don’t have a bonus, should probably concentrate on spring calving – the margins for producing milk over the winter are just too tight.
At last year’s Teagasc winter milk conference, Joe Patton outlined the optimum calving dates for herds with various levels of winter milk contract.
A herd with 25% liquid contract, should only calve 16% of the herd in autumn, with 8% calving in October, 5% calving in November and 3% calving in December. The rest of the cows should calve in spring.
A herd with 50% liquid contract should only calve 30% of the herd in autumn, with 16% calving in October, 12% calving in November, 4% calving in December and the rest calving in spring.
Joe says that only herds with more than 50% of their total milk pool as liquid milk should calve earlier than October.
He says the optimum calving spread for a herd with 70% of their milk in liquid contract is 55% calving in autumn – 30% in September, 20% in October and 5% in November.
An optimum calving rate is where just the liquid milk contract is filled. This means that all the milk being sold will be subject to the bonus. The rest of the milk can then be produced off grass from spring-calving cows where feed costs are lower.
Joe says that for every 5,000l per month of winter contract (October to March), an extra eight to 10 cows should calve in October.
From this, we can deduct that most liquid milk or autumn-calving herds in the Republic should start calving in October. Therefore, the start of breeding for cows and heifers should be in late December for the majority of herds, with only those with a very high proportion of liquid milk contract calving in September.
Sire selection
Generally speaking, autumn- or split-calving farms that produce milk over the winter have cows that
produce high volumes of milk
Joe Patton presented data from 2016 at last year’s conference showing that in the Glanbia region, liquid milk herds produce an extra 548l of milk per cow compared with manufacturing milk herds.
In the Aurivo region, liquid milk herds produce 1,022l per cow more than manufacturing milk herds. In Arrabawn, the difference is 832l and in LacPatrick, the difference is 661l.
The average milk yield per cow in liquid milk herds from these co-ops was 5,531l per cow in 2016. The average milk solids per cow in liquid milk herds was 418kg MS/cow compared with 367kg MS/cow in manufacturing herds, a difference of 51kg MS/cow.
There are a couple of take-home messages from this. Firstly, from the data presented, the yields being achieved in the liquid milk herds are lower than what you would expect to see. Now, it’s fair to say that the majority of these herds are split-calving herds, with the majority of cows calving in the spring. So the percentage of milk being produced solely over the winter may be small.
However, they produce 50kg of milk solids or 1,000l of milk more per cow on average than the average manufacturing herd. But we are not comparing 8,000 or 9,000-litre cows with 5,000-litre spring-calving cows.
The next thing Joe looked at was the calving interval. Liquid milk herds in Glanbia, Aurivo and Arrabawn had almost the same calving interval at 415 days.
Arrabawn liquid milk herds were a bit lower with a 406-day calving interval. The target calving interval is 365 days. So, on average, cows in the liquid milk herds were having a calf every 13.5 months.
Looking at the manufacturing milk herds in these co-ops, Joe found that calving interval was 397 days, again well short of the 365-day target. Both groups of farmers have work to do to achieve the fertility targets. Long calving intervals suppress the milk yield.
The fastest way to increase milk yield is to improve fertility by calving more cows in the first six weeks, having shorter calving intervals and by having fewer empty cows so a more mature herd. Therefore, focusing on breeding for fertility should be a priority for all farmers, not just spring calvers, or not just liquid milk calvers who are perceived to have poorer herd fertility. The fact is, herds in both systems have poor fertility.
To achieve this, only AI bulls with a high sub-index for fertility in their EBI should be used. Is EBI the right tool for winter milk herds? Uptake of the EBI system has been lowest in regions with the highest proportion of autumn- or split-calving. The average EBI of dairy herds in the Cavan/Monaghan region is €54, about half the national average. Within the Glanbia milk pool, the EBI of liquid milk herds in 2016 was €39 while it was €68 for manufacturing milk herds.
Fertility
Fertility has a 35% weighting in EBI, making it the biggest component of the EBI. The EBI has one of the highest weightings on fertility compared with other indexes around the world. Because fertility has a low heritability, placing a large weighting on it in the selection index means that only high fertility bulls rise to the top.
The data suggests that EBI is working with the national fertility data improving year on year, albeit from a low base. However, the important thing is that the Irish fertility statistics are going in the right direction. The same cannot be said for national statistics in most other countries.
So for me, it doesn’t make sense to be following another index. Across the world of confinement dairies where cows calve all year round, the focus of geneticists is on fertility. In Ireland, we are fortunate to have a genetic tool in place for the last 17 years that is improving fertility. Other genetic indexes, whether in the UK, Europe or North America, are playing catch-up. Yes, bulls with a higher genetic potential for milk volume are at the top of their lists, but do they last in herds? The answer on the ground is no.
High-EBI cows are more efficient converters of feed to milk. They have better fertility, last longer in herds and produce more valuable milk. Over their lifetime, they will produce more milk than cows with a higher breeding value for milk. Remember, fertility drives milk production so use the highest EBI bulls available.
Breeding management
It’s harder to identify cows in heat indoors than it is outdoors
Cows standing on concrete are in heat for a shorter time and do less mounting than cows outdoors. Tail paint is less effective on cows inside than on cows outside. This makes heat detection more difficult in winter than in spring with farmers relying more on visual observations than aids.
Some farmers find that providing a straw or woodchip area within or outside the cubicle sheds allows cows to express their heats better and they mount each other with less chance of injury.
Others use vasectomised bulls with chin ball markers to pick up cows in heat. Automated heat detection aids have become popular in autumn-calving setups, but reliability can be mixed.
Some of the older technology has heat detection rates of less than 90%. Some of the newer technologies might be more accurate.
Accuracy
I suppose it depends on the accuracy of the existing methods. If only 70% of heats are being detected with visual observations, increasing the heat detection accuracy to 90% will be beneficial at improving fertility and six-week in-calf rates.
The optimum calving date for most herds is early October, but earlier if a high proportion of milk is in a liquid contract.Actual milk yield in winter milking herds is lower than some might expect.The EBI has one of the highest weighting for fertility in the world so it should be used to pick bulls for use in winter milking herds.Automated heat detection has a role to play in winter milking herds if it is more accurate than visual observations.
The first question autumn-calving, or liquid milk, farmers should ask themselves is when to calve
Finding the correct calving date will inform the correct mating start date as it is 282 days prior to calving. The correct calving date comes down to the principles and objectives of the farm and the system.
In Ireland, producing milk over the winter without a bonus is a very costly exercise with very little margin. Therefore, only farms with a liquid or a winter milk contract or those guaranteed a bonus for all milk produced over the winter should calve cows in the autumn. Those that don’t have a bonus, should probably concentrate on spring calving – the margins for producing milk over the winter are just too tight.
At last year’s Teagasc winter milk conference, Joe Patton outlined the optimum calving dates for herds with various levels of winter milk contract.
A herd with 25% liquid contract, should only calve 16% of the herd in autumn, with 8% calving in October, 5% calving in November and 3% calving in December. The rest of the cows should calve in spring.
A herd with 50% liquid contract should only calve 30% of the herd in autumn, with 16% calving in October, 12% calving in November, 4% calving in December and the rest calving in spring.
Joe says that only herds with more than 50% of their total milk pool as liquid milk should calve earlier than October.
He says the optimum calving spread for a herd with 70% of their milk in liquid contract is 55% calving in autumn – 30% in September, 20% in October and 5% in November.
An optimum calving rate is where just the liquid milk contract is filled. This means that all the milk being sold will be subject to the bonus. The rest of the milk can then be produced off grass from spring-calving cows where feed costs are lower.
Joe says that for every 5,000l per month of winter contract (October to March), an extra eight to 10 cows should calve in October.
From this, we can deduct that most liquid milk or autumn-calving herds in the Republic should start calving in October. Therefore, the start of breeding for cows and heifers should be in late December for the majority of herds, with only those with a very high proportion of liquid milk contract calving in September.
Sire selection
Generally speaking, autumn- or split-calving farms that produce milk over the winter have cows that
produce high volumes of milk
Joe Patton presented data from 2016 at last year’s conference showing that in the Glanbia region, liquid milk herds produce an extra 548l of milk per cow compared with manufacturing milk herds.
In the Aurivo region, liquid milk herds produce 1,022l per cow more than manufacturing milk herds. In Arrabawn, the difference is 832l and in LacPatrick, the difference is 661l.
The average milk yield per cow in liquid milk herds from these co-ops was 5,531l per cow in 2016. The average milk solids per cow in liquid milk herds was 418kg MS/cow compared with 367kg MS/cow in manufacturing herds, a difference of 51kg MS/cow.
There are a couple of take-home messages from this. Firstly, from the data presented, the yields being achieved in the liquid milk herds are lower than what you would expect to see. Now, it’s fair to say that the majority of these herds are split-calving herds, with the majority of cows calving in the spring. So the percentage of milk being produced solely over the winter may be small.
However, they produce 50kg of milk solids or 1,000l of milk more per cow on average than the average manufacturing herd. But we are not comparing 8,000 or 9,000-litre cows with 5,000-litre spring-calving cows.
The next thing Joe looked at was the calving interval. Liquid milk herds in Glanbia, Aurivo and Arrabawn had almost the same calving interval at 415 days.
Arrabawn liquid milk herds were a bit lower with a 406-day calving interval. The target calving interval is 365 days. So, on average, cows in the liquid milk herds were having a calf every 13.5 months.
Looking at the manufacturing milk herds in these co-ops, Joe found that calving interval was 397 days, again well short of the 365-day target. Both groups of farmers have work to do to achieve the fertility targets. Long calving intervals suppress the milk yield.
The fastest way to increase milk yield is to improve fertility by calving more cows in the first six weeks, having shorter calving intervals and by having fewer empty cows so a more mature herd. Therefore, focusing on breeding for fertility should be a priority for all farmers, not just spring calvers, or not just liquid milk calvers who are perceived to have poorer herd fertility. The fact is, herds in both systems have poor fertility.
To achieve this, only AI bulls with a high sub-index for fertility in their EBI should be used. Is EBI the right tool for winter milk herds? Uptake of the EBI system has been lowest in regions with the highest proportion of autumn- or split-calving. The average EBI of dairy herds in the Cavan/Monaghan region is €54, about half the national average. Within the Glanbia milk pool, the EBI of liquid milk herds in 2016 was €39 while it was €68 for manufacturing milk herds.
Fertility
Fertility has a 35% weighting in EBI, making it the biggest component of the EBI. The EBI has one of the highest weightings on fertility compared with other indexes around the world. Because fertility has a low heritability, placing a large weighting on it in the selection index means that only high fertility bulls rise to the top.
The data suggests that EBI is working with the national fertility data improving year on year, albeit from a low base. However, the important thing is that the Irish fertility statistics are going in the right direction. The same cannot be said for national statistics in most other countries.
So for me, it doesn’t make sense to be following another index. Across the world of confinement dairies where cows calve all year round, the focus of geneticists is on fertility. In Ireland, we are fortunate to have a genetic tool in place for the last 17 years that is improving fertility. Other genetic indexes, whether in the UK, Europe or North America, are playing catch-up. Yes, bulls with a higher genetic potential for milk volume are at the top of their lists, but do they last in herds? The answer on the ground is no.
High-EBI cows are more efficient converters of feed to milk. They have better fertility, last longer in herds and produce more valuable milk. Over their lifetime, they will produce more milk than cows with a higher breeding value for milk. Remember, fertility drives milk production so use the highest EBI bulls available.
Breeding management
It’s harder to identify cows in heat indoors than it is outdoors
Cows standing on concrete are in heat for a shorter time and do less mounting than cows outdoors. Tail paint is less effective on cows inside than on cows outside. This makes heat detection more difficult in winter than in spring with farmers relying more on visual observations than aids.
Some farmers find that providing a straw or woodchip area within or outside the cubicle sheds allows cows to express their heats better and they mount each other with less chance of injury.
Others use vasectomised bulls with chin ball markers to pick up cows in heat. Automated heat detection aids have become popular in autumn-calving setups, but reliability can be mixed.
Some of the older technology has heat detection rates of less than 90%. Some of the newer technologies might be more accurate.
Accuracy
I suppose it depends on the accuracy of the existing methods. If only 70% of heats are being detected with visual observations, increasing the heat detection accuracy to 90% will be beneficial at improving fertility and six-week in-calf rates.
The optimum calving date for most herds is early October, but earlier if a high proportion of milk is in a liquid contract.Actual milk yield in winter milking herds is lower than some might expect.The EBI has one of the highest weighting for fertility in the world so it should be used to pick bulls for use in winter milking herds.Automated heat detection has a role to play in winter milking herds if it is more accurate than visual observations. 
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