ABSTRACT.
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

Jesús I. Vega-García1, Ernesto Morales-Almaraz2, Felipe López-González1, Julieta G. Estrada-Flores1, and Carlos M. Arriaga-Jordán1*
 
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.
Keywords: Alternative forage, CLA, grazing, PUFA, silage.
1Universidad Autónoma del Estado de México, Instituto de Ciencias Agropecuarias y Rurales (ICAR), Campus UAEM El Cerrillo, CP 50090 Toluca, Estado de México, México. *Corresponding author (cmarriagaj@uaemex.mx).2Universidad Autónoma del Estado de México, Facultad de Medicina Veterinaria y Zootecnia, Campus UAEM El Cerrillo, CP 50090, Toluca, Estado de México, México.