3 April 1998

Investigating fish oil diets

LAMBS fed on linseed or fish oil produce higher quantities of valuable fatty acids in muscles than those on standard diets.

Effects of increasing levels of polyunsaturated fatty acids (PUFAs) in sheepmeat by altering lamb diets was studied at Harper Adams Agricultural College, Shropshire and Bristol University.

"Lamb is quite high in saturates, so there is an advantage to increasing the levels of polyunsaturates, as recommended by the department of health, particularly the n-3 types. We wanted to see if we could achieve this," explains Liam Sinclair of Harper Adams.

Seventy two male lambs from three breeds – Friesland x Lleyn, Soay, and Suffolk x Lleyn – were penned individually and allocated to one of four diets based on dried grass with identical energy, protein and fat analyses. Diet one was a Megalac control; diet two included linseed, diet three fish oil, and diet four, a 50:50 mixture of linseed and fish oil.

Fish oil significantly depressed intake and liveweight gain but had no significant effect on feed conversion ratio.

Compared with the controls, animals on the linseed diet had twice the quantity of the PUFA alpha-linolenic acid and increased levels of EPA and DHA.

Fish oil alone increased EPA and DHA acids by three to four times while the mixed diet results in n-3 PUFA levels between the linseed and fish oil diets.

Dr Sinclair believes that by protecting feed sources of the PUFAs from saturation in the rumen, it would be possible to increase levels in sheepmeat further still.

"Were examining how to protect linseed – the only major plant source of n-3 fatty acids other than grass." &#42

Linseed or fish oil diets increase fatty acids in sheepmeat.