Herd fertility management in the spring

Date published: 11 May 2017

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Taking your eye off fertility at this time of the year can have major implications in nine months time. An 8,000 litre cow that should ideally calve in February 2018 must become pregnant in May 2017. If pregnancy is delayed, the cow will either still be dry or in late lactation next February yielding about 14 litres when she should be approaching a peak milk yield of 37 to 38 litres. Extended calving intervals thus have major cash flow and profitability impacts for dairy farm businesses.

Photo caption: Grazing cows fitted with activity monitors to aid heat detection.

Getting high yielding dairy cows in calf

Getting high yielding Holstein dairy cows in calf can be a challenge at any time of the year. Maintaining consistent energy intakes during the breeding period and ensuring adequate protein intakes is essential for acceptable herd fertility. Managing consistent intakes of grazed grass is always a challenge. The inevitable question at this time of year for many dairy farmers therefore becomes, should I let my high yielders out to graze?

The concentrate feed savings from grazing high yielding cows (>35 litres) is much less than with low to moderate yielding cows, as the high yielding cow will always require considerable concentrate feeding. To optimise herd profitability, low and moderate yielding cows should be grazed full-time, where feasible. What should be done with high yielders depends on how many there are in the herd. Are there enough to justify keeping a batch of high yielding cows housed full-time? Do you have drafting facilities to allow high yielders to be housed at night while grazing the rest of the herd?

Maintaining fertility with grazing cows

Managing grass quality through grass budgeting and adjusting concentrate composition and feeding levels according to grazing conditions are key nutritional considerations. Beyond good grazing management, how can you improve fertility management at grass?

Heat detection in grazing cows

The key management factor to reduce calving intervals that is under the farmer’s control is heat detection. When turning cows out to graze, avoiding interruptions to breeding management routines is critical. Farmers grazing dairy cows must consider how they are going to detect cows on heat at grass. A wide range of heat detection methods and aids are available to assist heat detection with grazing dairy cows. The pros and cons of the main options are highlighted below.

  • Visual observation – do you observe often and for long enough? Observation at milking times only results in too many missed heats. If relying on visual observation, cows must be observed in the field outside of milking time to achieve acceptable submission rates.
  • Tail paint and Kamars – will you take time to check these aids and to to-up tail paint and apply kamars? Proprietary aerosol spray and bottle-brush tail paint products are readily available to tail paint and colour code cows at different stages of the breeding cycle and are proven aids to heat detection for grazing dairy cows. Well managed seasonal spring calving herds achieve submission rates of 95% with the aid of tail paint.
  • Electronic heat detection aids – do the computer algorithms take account of variable walking distances and can the software be adjusted to grazing settings? Talk to your supplier to ensure you are using the optimal settings for your equipment.
  • Stock bull – is he fertile? How will you track which cows the bull has served? Many farmers rely excessively on stock bulls. Without accurate recording of service dates repeat breeding cows requiring veterinary treatment may be missed. Over reliance on stock bulls may also result in a loss of control over drying off and calving dates, if not combined with regular pregnancy diagnosis. Painting the bull’s brisket on a daily basis with fluorescent paint can help track served cows.
  • Veterinary examination - regular pregnancy diagnosis and veterinary examinations are critically important to find problem cows early and to ensure they are appropriately treated to become pregnant. Good fertility management teamwork with your vet is a good return on investment.

Spring and early summer are busy times of the year for dairy farmers. Each herd manager must consider how he or she plans manage herd fertility and detect cows on heat and over the coming months. The opportunity exists to substantially improve cash flow in nine months time by paying attention to fertility now. 

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