The polyunsaturated fatty acid status of foetal and neonatal ruminants

1. Information on the fatty acid composition of tissues of foetal calves, neonatal lambs, deer and piglets reported by Payne (1978) has been quantified by the use of an internal standard during analysis, to give concentrations of total polyunsaturated fatty acids (PUFA) derived from linoleic acid (ω6) and linolenic acid (ω3) expressed on a per kg tissue basis. The total concentration of both acids (ω6+ω3) was similar in all tissues examined except brain. Because muscle, the main constituent of the soft tissues of young animals, contains about 40–50 % of the total body content of these acids, it is considered that muscle concentrations are a reflection of total body status of these acids.2. Concentrations in muscle of both ω6 derivatives and total PUFA were significantly lower in the neonatal lamb and foetal calf than in the mature animal whereas in pigs and deer the concentrations in the young animal were similar to those in the mature animal. Concentrations of ω6 derivatives and total PUFA in lambs were significantly lower than those in calves; the presence of ω3 derivatives reduced the level of significance for total PUFA. Again, total PUFA content did not differ significantly between the piglet and the young ruminants.3. There was a substantial placental transfer, with apparently a preferential transfer of ω3 derivatives.4. In brain the levels of ω3 acids were as high in the foetal and neonatal animals as in mature animals. The levels of ω6 acids were lower in young animals.5. Calculations of ω6 intake from milk showed that the total deficit of ω6 could be made up within a few days.6. It was concluded that the extent of deficiency of ω6 in young ruminants raised in a grazing situation, as in New Zealand, is marginal and any feeding to overcome this is unlikely to be of any benefit.