Black oat (Avena strigosa schreb.) grazing or silage for small-scale dairy systems in the highlands of central Mexico. part ii. fatty acid profile of feed and milk

Abstract

There is growing interest for health attributes in foods, and milk contains polyunsaturated fatty acids (PUFA) beneficial for human health, being forages a main source for dairy cows. This research addressed the hypothesis that black oat (Avena strigosa Schreb.), either grazing regrowth or as first-cut silage in the dry season, is a forage option for small-scale dairy farmers in the central highlands of Mexico. This study presents fatty acid profile of feeds and milk. In Experiment 1 cows grazed for 8 h d-1 black oat regrowth (BKO), black oat associated with red clover (BKC) or a multi-species pasture (MSP) of perennial ryegrass, festulolium, and white clover as treatments, and in Experiment 2 treatments were 2.5 (T1), 5.0 (T2) or 7.5 (T3) kg DM cow-1 d-1 of black oat silage (BOS) as complement to grazing. Nine Holstein cows were used in both experiments, in groups of three randomly allotted to treatment sequence in a 3×3 Latin square design replicated three times. Cows also received 4.6 kg DM d-1 commercial concentrate. In Experiment 1 there were significant differences (P < 0.05) in content of saturated fatty acids (SFA) for BKO (62.4 g 100 g-1) 2.8% lower than MSP (64.8 g 100 g-1), monounsaturated fatty acids (MUFA) in MSP (31.4 g 100 g-1) were 6.5% lower than BKO (33.6 g 100 g-1), and PUFA in BKO (4.0 g 100 g-1) were 5% higher to BKC and MSP (both with 3.8 g 100 g-1). In Experiment 2 there were nonsignificant differences (P > 0.05) between treatments in fatty acid groups. Grazing black oat regrowth resulted in milk with higher PUFA contents compared to multispecies pasture representing more benefit for health; but no effect with ensiled black oat.