A study reported by AFBI scientists, Dr Aidan Cushnahan and Dr Conrad Ferris, suggests early lactation cows fed by-product feeds had slightly higher energy-corrected milk yields than cows fed diets based on cereals and soyabean meal.

The study considered two main topical/ethical issues. The first was whether the likes of maize and wheat (which can be consumed by humans) can be easily replaced in cow diets by low human edible feeds such as sugar beet pulp and wheat feed.

The second issue relates to the climate impact of using soya, particularly if it is linked to deforestation. It was replaced by ingredients including rapeseed meal, distillers grains and maize gluten.

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Results showed that cows offered concentrates with low cereals and soyabean meal (high levels of by-products), had a higher total feed intake, energy corrected milk yield and fat plus protein yield.

However, reducing the human-edible fraction in the concentrate led to an increase in phosphorus concentration by up to 75%. Ultimately, that could worsen the problem of phosphorus balance on dairy farms.