Part 9. Transition into lactation

Introducing the heifer into the herd

During the period around first calving, dairy herd replacements are exposed to many changes which, if not managed, can result in nutritional, physiological and social stress. These types of stressors can have long-term effects on subsequent milk production, fertility, health and welfare.

Training heifers to the parlour

Training heifers prior to calving to the milking routine has been suggested as a way to reduce stress in early lactation. The AFBI/CAFRE heifer survey indicated that 58% of producers adopt this practice. Research has shown that while there is a benefit of increased milk yield in early lactation – 1.3 kg/day over the first 100 days of lactation, and a significant reduction in somatic cell count (95,000 versus156,000), there were negative effects on fertility.

Introducing heifers into the herd

The majority of producers introduce dairy heifers straight into the dairy herd after first calving.  However, some producers form small groups of calved heifers (or heifers/mature cows) and introduce these groups into the milking herd together. This approach is likely to be beneficial, based on the findings of recent research at AFBI Hillsborough.  This work found that heifers introduced to the milking herd as pairs rather than individually had higher milk yields in early lactation (2 kg/day during the first month of lactation) without detrimental effects on fertility.  Behavioural observations indicated the paired heifers were less fearful than those introduced into the milking herd as individuals. Delaying the introduction of heifers (as singles) into the herd from day 1 to day 7 post-calving had no benefits on performance or behaviour.

A small study in GB has indicated that heifers find it easier to integrate if they are introduced into the milking herd after the evening, rather than the morning, milking.  Cows are less socially active in the evening thus heifers may have time to settle into the pecking order more easily.  Work funded by DARD and AgriSearch will examine this, and other management options, to enable improved transition management to be developed for dairy herd replacements.

Managing heifers as a separate group

Work carried out some years ago in GB and in Denmark reported significant benefits from housing heifers separately from mature cows. These responses were the result of heifers grouped separately spending 10 to 30 minutes longer per day eating compared with heifers grouped with older cows.  It was suggested that this difference in intake was due to the fact that first lactation heifers mixed with mature cows follow the same eating pattern as the cows (social facilitation).  Since mature cows eat faster than first lactation heifers, the eating time for heifers mixed with cows is reduced compared to the situation when heifers are housed as a single group.  With complete diets, the effects of housing heifers separately have been found to be less, or totally absent, perhaps as a result of total time feeding being less of a limitation on total dry matter intake.

Housing first lactation animals separate from mature cows undoubtedly complicates feeding and management and is only practiced by a very small number of dairy producers in Northern Ireland (less than 1%).  Research information in this area is limited, particularly in relation to effects on reproductive performance, incidence of mastitis and lameness.  Nonetheless, in some housing systems the separation of heifers from mature cows during the first lactation may be a practical and cost-effective practice.

Housing systems

There is clear evidence that feet lesions in first lactation heifers are greater when animals are housed in cubicle accommodation compared with straw yards.  Housing heifers for 4 to 8 weeks after calving on straw before moving to cubicle accommodation has been found to significantly reduce the severity of feet lesions.  However, even this limited period of housing heifers on straw would have a significant impact on the costs of production and it is also important to consider that there is an increased risk of environmental mastitis with animals on straw bedded courts.  With cubicle accommodation, emphasis must be placed on adequate number of cubicles and making them as comfortable as possible to maximise lying time and hence reduce the incidence of lameness.

Main messages

1.      Training heifers to the milking parlour has only short-term benefits on milk yield and somatic cell counts, and this has not been accompanied by improved fertility (in fact the opposite has been the case in the AFBI study).

2.      Form small groups of heifers (2+) before introducing them into the main milking herd.

3.      Housing heifers separately from mature cows during the first lactation may have benefits but complicates management and has been adopted by a very low percentage of producers.

4.      Housing heifers on straw for 4-8 weeks post-calving reduced lameness but again is not a practical option on most systems. With cubicle accommodation emphasis must be placed on and adequate number of cubicles made as comfortable as possible in order to ensure optimum comfortable lying time.