How to hit replacement heifer targets

For most parts of the country, grassland management has proven a struggle to date this year, given the contrasting rain levels between early and mid/late summer, contributing to sporadic periods of sustained high growth rates.

However, as we approach the later quarter of the grazing season, it is important to maximise perfomance off grass, while also setting the platform up correctly for Spring 2024. As always, we’re hoping to control the decline in milk production from here to the end of lactation. Milk yield in normal conditions will drop off 2.5% per week or 10% per month once we get to mid lactation.

heifers grazing in a field

Energy Deficit  

Any drop greater than this indicates an energy deficit, which would signal deteriorating grass quality or where a deficit occurs, the herd’s dry matter intake capacity may not be being met. However, milk protein and butterfat should be incrementally increasing at this point, with the target being at least +0.05% per month. Milk protein is energy based and where grass quality has suffered, summer milk protein percentages have been similarly impacted.

Next Generation

It is also a good time to reassess where we stand with the next generation of milking cows – that heifers are still on track to achieve their target weight for age (% of mature weight). Weighing now compared to weighing at the point of housing provides the opportunity to identify heifers that are behind target, and to make alternative plans where these targets are not being met.

The threshold figure for 2022 spring born weanling heifers is approximately 198kg in mid-September (33% of an assumed mature weight of 600kg). Heifers that are lighter than this should be separated into their own group and given priority access to high quality grass and supplementary concentrates (depending on how below target they may be).

Higher weight gains can be achieved from grass rather than from winter/silages diets and a good response to autumn supplementation can be achieved. Research shows that youngstock at grass in summer can achieve weight gain of 0.85kg/day on grass only. While in the autumn where 1kg of concentrate plus high-quality grass is offered, Average Daily Gains of 1kg/head/day can be achieved.

For more information, contact your local Agritech Sales Advisor.

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