Effect of volume weight of oats and barley on fatty acid content of milk fat

Abstract

Feeding oats has been shown to cause beneficial changes in milk fatty acid composition characterised as a reduction in saturated and increased monounsaturated fatty acids compared with barley (Kankare & Antila 1984, Martin & Thomas 1988, Tesfa et al. 1992, Ekern et al. 2003). Unfavourable weather conditions during the growing season may cause crop failure leading to low volume weight. The effects of different volume weights of both oats (33, 43, 51, 61 kg/hl) and barley (31, 38, 57, 69 kg/hl) on milk fatty acid composition were studied with 16 Finnish Ayrshire cows in a replicated (n=2) 4x4 Latin square experiments with 4-week periods. Grass-red clover silage was fed ad libitum with 8 kg concentrate, which included 86% oats or barley, 10% rapeseed meal and 4% minerals + vitamins. Mean proportion of oats and barley concentrate consumption was 0.39 of dietary dry matter. Crude fat content of oat based concentrates were over twice that of barley containing concentrates (5.9, 5.6, 6.8, 6.6% vs. 2.6, 2.5, 2.6, 2.6%, respectively). Lipid in oats contained approximately 2.8 times higher oleic acid and 1.4 times lower palmitic and linoleic acid and 3.4 times lower linolenic acid relative to barley. Differences in milk fatty acid composition due to variations in volume weight were small, although statistically significant in some cases. Fatty acid content of milk (% of total fatty acids) produced with oats and barley of different volume weights from the lowest to the highest respectively were: palmitic acid 29.3, 29.9, 28,7, 28.5 and 34.7, 34.8, 34.4, 35.4; stearic acid 13.6, 13.3, 13.7, 13.9 and 10.3, 10.0, 9.3, 9.4; oleic acid 23.7, 22.1, 23.4, 23.9 and 18.3, 17.3, 16.3, 16.8; linoleic acid 0.8, 1.2, 1.0, 1.2 and 1.2, 1.2, 1.4, 1.4; linolenic acid 0.7, 0.7, 0.7, 0.7 and 0.6, 0.6 0.8, 0.8. In conclusion, failure of oats or barley crops has little effect on milk fatty acid composition. Oats are recommended for dairy cow feeding due to a more desirable fatty acid composition of milk for human nutrition compared with barley. Ekern, A. et al. 2003. Acta Agriculturae Scandinavica, Section A, Animal Science 53: 65-73; Kankare, V. & Antila, V. 1984. Journal of Agricultural Science in Finland 56: 33-38; Martin, P.A. & Thomas, P.C. 1988. Journal of the Science Food and Agriculture 43: 145-154; Tesfa, A.T., et al. 1992. Agricultural Science in Finland 1: 255-264.