The use of extended lactation (EL) within Victorian dairy farming systems is now considered commercially viable. With research information now available and farmer experience growing, an informed decision can be taken by farmers and advisors regarding use of EL.
It is increasing difficult to maintain a seasonal calving pattern. The modern dairy cow is capable of lactations well beyond the traditional 300 days. This provides dairy farmers with new management options. EL is a system that suits the modern cow. It is a flexible system for the future.
Which cows are suited to EL?
Cows with a high proportion of North American Holstein genetics are suited to EL. Heifers tend to have more persistent lactations than cows. Which cows are suited to EL?
Will I produce less milk?
On average, persistence of lactation is high for 15 and 18 month inter-calving intervals with less persistence for longer lactations. There is significant variation between animals. With longer inter-calving intervals than 18 months, some cows do not persist to the planned dry-off date. However, the top 50% of cows were found to produce a similar amount of milk solids in a 22 month lactation to the top 50% of herd mates joined for two traditional 10 month lactations. The lower 50% produced less milk solids in a 22 month lactation.
Daily milk production is less in the extended lactation phase but the extra days in milk and higher milk solids concentration are compensating factors. Compared to traditional 10 month lactations, 13 and 16 month lactations can produce similar annual milk solids. For lactations of 19 to 22 months, a drop in annual average milk solids production of 2 to 10% has been measured. Cows with lower persistence can become over-conditioned during late lactation and this needs to be managed in the dry period.
Milk in the extended lactation phase is higher in milk solids, with the rise in protein test usually being greater than fat test. Per litre, extended lactation milk is more valuable.
Does feeding affect lactation presistence?
Persistence of lactation is not dependent on a high level of nutrition with similar persistence with a 160 MJ ME/cow/day diet as with a 180 MJ ME/cow/day diet.
Cows in the extended lactation phase are very responsive to supplementary feeding. Cows are able to respond well following periods of reduced feeding. Hence, extended lactations are not dependant on a consistent level of feeding.
Read more about the persistence of lactation.
Is EL profitable?
Economic analysis has found extended lactation systems can compare favourably with a traditional lactation system under a range of conditions, but with all things, it depends. Economics of traditional 300 day lactations have been compared to 18 month lactations in a split calving pattern. Key factors associated with higher profitability of EL were lower herd replacement rates/less rearing costs, increased milk income, lower concentrate costs, and less breeding and animal health costs. However, livestock trading was lower than for a traditional calving system. Extended lactation had lower capital costs associated with investment in cattle.
Farmers may consider systems other than those studied.
Why might EL be considered?
- There is considerable intensity of work associated with calving. Less calvings in a life-time means a reduction in workload.
- Most animal health problems and associated costs are associated with calving.
- It is difficult for the modern cow to maintain a 12 month inter-calving interval. The modern cow needs more days open between calving and mating to reach peak reproductive performance. As a result, high culling rates are required to maintain a tight seasonal (annual) calving pattern.
- In an EL system, treatment for non-cycling may not be needed (applies especially to heifers).
- Less heifer replacements are required in an extended lactation system.
- A modern herd of Holstein cows can produce similar annual average milk solids from lactations up to 16 months.
- The top 50% of cows in a herd produce similar annual average milk solids from lactations up to 22 months
- There are price incentives for milk produced outside the peak supply months.
- Read more on: Will genetic progress change?
Some possible uses of extended lactation
Tightening the calving pattern / retaining valuable herd members
Delaying the mating of some cows until the next joining period will tighten up the calving pattern, retain valuable cows in the herd, eliminate the need for calving inductions and will require less replacements to be reared to maintain herd numbers. So extending the lactation of selected cows by delaying mating until the next joining period can make good business sense.
The modern high producing cow needs more time between calving and mating. Late calving cows have a low probability of getting in calf within a seasonal calving pattern. High producing and late cows are good candidates for extended lactation. Heifers are better suited than cows, producing slightly more milk in the extended lactation phase than in the first 300 days of a two-year lactation.
Smoothing out the workload
Peak work load associated with a single seasonal calving pattern can be avoided by split calving. Use of extended lactations in a split calving pattern can further reduce workload associated with calving. Cows on 18 months inter-calving intervals have 2/3rds the calvings over a lifetime.
Changing the calving pattern
For some, there is a desire to change the calving pattern in response to changes in feed supply and/or milk price. It is a simple matter to delay the mating of cows; joining them at the appropriate time to move them to the desired calving date.
Deliberate use on high producing cows
High producing cows are in negative body condition for a considerable length of time. It is thought that modern Holsteins require 100 days open to achieve optimum reproductive performance. High producing cows have good lactational persistence and are candidates for deliberate delaying of mating until after 100 days open. This approach requires multiple calving/joining periods within a year.
Read about how four farmers in Victoria have used extended lactation in our case studies.
For more information contact:
Greg O'Brien, Ellinbank (03) 56242288
Ash Michael, Leongatha (03) 5662 9901
The contribution of major funders Gardiner Foundation and the former DEPI Victoria, together with support funding from GippsDairy and DHIA is gratefully acknowledged. EL research was conducted by Chris Grainger, Martin Auldist, Greg O'Brien, Bill Wales, Jock MacMillan and Bill Malcolm.