Soy alternatives in dairy rations

SAC Consulting, part of SRUC, has been exploring the use of alternative, high-performing proteins in dairy feed rations for farmers.


cotland’s Rural College (SRUC) conducted a study in which they removed soya from the rations of three of its dairy herds and analysed the impact of protein alternatives on their productivity. The three herds,

based in Dumfries and Galloway on Arla contracts, are SRUC Crichton Royal Farm, home to the Langhill Research Herd (200 cows); Acrehead (210 cows); and SRUC Barony Campus dairy herd (200 cows).

No change in milk output or composition Lorna MacPherson, Dairy Consultant with SAC Consulting, ex- plains that in the study the SRUC dairy farms stopped feeding soy in the total mixed ration (TMR) to both milking and dry cows in April last year. They also formulated new diets with more rapemeal and distillers wheat dark grains, and with

protected rapemeal, which was added to provide quality by-pass protein. SAC monitored output over three months, with the data showing that there wasn’t much change in milk output or milk composition after excluding soy from the cows’ diet.

Same level of protein and energy Three feed blends, which were reformulated without soy, were designed to have the same level of protein, bypass pro- tein, and energy content as the soy-based blends. Soy hulls were also replaced with sugar beet pulp and palm kernels to maintain NDF levels. MacPherson: “Farmers shouldn’t be afraid of not using soy in their rations. There is now plenty of evidence and trials are being conducted showing that pro- tected rapemeal is a viable alternative to soya and can be used with no detriment to milk yield or quality.”

Protected rapemeal as a viable alternative Protected rapemeal is conventional rapemeal that is treated, either by heat or a chemical process, to increase the bypass protein content, reducing its digestibility in the rumen and increasing the proportion that passes through the rumen in- tact for digestion in the small intestine. It also increases the availability of the essential amino acids lysine and methio- nine in the small intestine, which can benefit milk yield and milk protein content. There are many protected rapemeal products available which have a similar or greater bypass pro- tein content to that of soy. Although both conventional and protected rapemeal are cheaper per tonne, farmers will have to feed more of these alternatives to reach the same protein content in the diet when replacing soy, according to MacPherson. “A downside is that this means there is less space in the ration to use your own forage or cereals; so, in some sense, soy is a space saver.”

In the study the SRUC dairy farms stopped feeding soya in the total mixed ration. 36 ▶ ALL ABOUT FEED | Volume 29, No. 1, 2021

Public perception According to the dairy consultant not all soy production is bad: “There’s a public perception that vast areas of rainforests are being cleared for its production. This is not always the case and soy can be sourced that is certified responsible with a ze- ro-deforestation assurance. However, with a growing environ- mental lobby and bold ambitions from retailers, growing soy alternatives may offer opportunity for farmers in Scotland.”


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