Efficiency, fertility, emissions, and profit are all linked, Phil Garnsworthy, Professor of Dairy Science at University of Nottingham’s School of Biosciences told the BCBC conference in January.
Milk yield is the main driver of production efficiency, and milk yield per hectare is the main driver of whole farm efficiency. However, any efficiency gains are partly offset by lower fertility said Prof Garnsworthy, who was awarded the Sir John Hammond Award in 2022. Over the past 30 years yields have increased, but fertility of the dairy cow has fallen.
“Poorer fertility and poorer oestrus detection meant that more cows were being culled because they were not in calf.” This meant that more replacements were needed to be reared resulting in a reduced herd efficiency.
Calving intervals also play a part. “If you have fertile cows with 365-day calving intervals then in a four-year period they will have four lactations, whereas your average cow with a longer 410-day interval will only have three lactations.
“A cow with four lactations will give 27% more milk over her lifetime, she will eat 12% more energy and efficiency and net energy goes up from 0.32 to 0.34 so that’s an 11% increase.” Feed and methane ‘costs’ of rearing are therefore spread across more kg of milk, further improving production efficiencies.
The key to improving whole farm feed efficiency is to improve milk yield per hectare, he said. Improving quality and utilisation of grass and forage allows a farm to increase its livestock numbers and manage feed better to reduce wastage.
“Ensure you manage youngstock to make sure they reach their age and weight targets and the main thing is maximise fertility and health to reduce animal wastage and reduce replacement rates.” Heifer losses and age at first calving impact efficiency too, but the biggest drive is fertility culls. “It has a huge effect on the overall efficiency of the farm because it affects how many heifers are on the farm and how many litres the cow gives in her lifetime.
Sexed semen had been a ‘gamechanger’ for producing female replacements. “It now accounts for 70% of dairy inseminations according to AHDB, which means each cow can now produce 1.95 potential heifer replacements. This still doesn’t overcome the effect of replacement rate on efficiency though,” he said.
He encouraged delegates to consider the three pillars of sustainability – society and economics as well as the environment – and that improving fertility has positive effects on all three.
Pieter van Goor from CRV and farmer Wietse Duursma shared their experiences of improving feed efficiency in The Netherlands. Pieter said: “The 25% best cows for feed efficiency in your herd need a quarter less feed to produce the same amount of fat and protein corrected milk as the lower performing cows.”
Photography Credit @Jenny Wood Photography