For many parts of the country, grass quality has been somewhat of a struggle and now that some welcome rain has arrived, it is important that our focus returns to achieving optimum dairy herd performance from grass with our priority groups of animals; the main milking herd and our replacement heifers.
Milking Cows
As always, we are hoping to control the decline in milk production from here to the end of lactation. Milk yield in normal conditions will drop by off 2.5% per week or 10% per month once we get to mid lactation. Any drop greater than this indicates an energy deficit – which would signal that grass quality is deteriorating or the herds dry matter intake requirement is not being met. However, milk protein and butterfat should be incrementally increasing at this point, with the target being + 0.05% per month. Milk protein is driven by energy and where grass quality has suffered, so too has milk protein percentages this summer.
Replacement Heifers
It is a good time to reassess where we stand with the next generation of milking cows. Ensure that heifers are still on track to achieve their target weight for their age (% of mature weight). By weighing now, compared to weighing at the point of housing, this allows the opportunity to identify heifers that are behind their target, and make alternative plans for those that are not on track. The threshold figure for 2022 spring-born weanling heifers is approximately 190 kg in mid-September (approximately 33% of an assumed mature weight of 570 kg). 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 are.
Higher weight gains can be achieved from grass compared to winter/silage diets and a good response to autumn supplementation can be achieved. Research shows that youngstock at grass in summer can achieve weight gain of 0.85 kg/head/day on a grass only diet. While in the autumn, where 1 kg of concentrate plus high-quality grass is offered, an
More Information:
For further advice on mid-lactation cow and replacement heifer nutrition, contact your local Agritech Sales Advisor.