SUSTAINABILITY FEED & ADDITIVE MAGAZINE July 2024 57 Quality nutrition fed at higher levels can help farmers capitalise on investments in genetics. Proper feeding shows up in herd longevity, leading to enhanced profitability and a reduction in the herd’s carbon footprint. It has been estimated that reducing age at first calving, reducing replacement rates and improving production combined can reduce footprint by approximately 9% (depending on the original starting point). REACHING FIFTH LACTATION Given that replacement rates are in the range of 33%, animals rarely reach their third lactation, which is where they fully express their genetic potential for milk production. Research by de Vries et al (2020) has shown that the fifth lactation is the optimal point for expressing genetic potential, bringing new genetics into the herd and for aged cow cost. With this research in mind, dairy producers should be aiming for optimal replacement rates of 20%. BUT HOW DO WE GET TO THE FIFTH LACTATION? Correct calf rearing is the first step in the process. Next, it is important to ensure that heifers calve at 22-24 months and have a healthy transition into their first lactation, continuing to milk and transition well into subsequent lactations. Most culling events occur in the first 100 days in milk. Precision nutrition is key to ensuring optimal dry matter intake (DMI). Balancing protein and energy helps support a smooth transition to milking. Precision nutrition also encompasses mineral nutrition which is often overlooked. Feeding too large an amount of minerals can be just as harmful as feeding too little, so it is important to get the balance right. Responsible mineral nutrition can also save money and be more environmentally friendly. ENSURING RESPONSIBLE MINERAL NUTRITION Responsible mineral nutrition is important at all life stages, from calf through the fifth lactation. Many producers are overfeeding key trace elements, so ensure that minerals are formulated responsibly. Review all background sources, including forage and any other mineral sources, being fed. Formulating diets
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