Fertility remains a key performance indicator for grazing cow herds, particularly in spring-calving systems where compact calving blocks are essential.
One of the major challenges in maintaining high fertility levels is ensuring cows, especially high-yielding, early lactation animals, achieve adequate energy intakes at grass. These cows have high nutritional demands and failure to meet these through grazing alone can quickly lead to negative energy balance, loss of body condition and ultimately, reduce conception rates.
Grass based systems offer cost effective nutrition, but the reliability of this feed source is heavily influenced by weather conditions. Prolonged wet periods or cold snaps can severely limit grass growth and quality, leading to reduced dry matter intake.
Even in ideal weather, achieving the necessary intakes from grass alone can be difficult. Grass dry matter content, bite rate and grazing time all affect how much a cow can consume in a day. When conditions are sub-optimal, supplementary feeding such as additional concentrate feeding or provision of a buffer feed of silage, at milking times may be necessary to avoid compromising fertility.
Strategies to maximise fertility during the grazing season:
- High quality grass should be the foundation of the diet, and this begins with maintaining productive swards. Regular reseeding helps ensure a high proportion of leafy, digestible species, which are more palatable and higher in energy.
- Cows should ideally graze grass at the 3-leaf stage and at covers of approximately 3000kg DM/ha to maximise intake and digestibility.
- Paddock size must also be carefully managed – if the area allocated is too tight, cows will not meet their daily intake requirements. Target should be at least 15kg DM of grass in a full-time grazing system.
- Additionally, pre-mowing or on/off grazing during difficult weather conditions can help manage intake and utilisation more effectively.
- Body condition scoring can guide intervention strategies.
To improve fertility at grass, consider targeted supplementation during early lactation. Focus on feeding an energy dense, cereal based concentrate which includes a high specification mineral trace elements such as copper and selenium, should not be overlooked, as deficiencies can impact reproductive performance.
Culling decisions also play a role. Cows over 200 days in milk (DIM) and not in calf should be critically accessed. With current strong cull cow prices, retaining empty cows may not be economically viable, especially if they are low yielders or poor performers.
In summary, while grass based systems are economically attractive, strategic grazing management, timely reseeding and careful monitoring of cow performance are key to maintaining high fertility in grazing herds.
For tailored advice on fertility at grass, please contact your local Fane Valley Feeds Advisor or call 028 8224 3221.
