Abstract

The study was performed to compare milk quality on goat cheese managed under different feeding systems: exclusive grazing (EG), supplemented grazing (SG) or full confinement (FC). Sampling was obtained in 2020 and 2021 on 1418 dairy goats from Querétaro, Michoacán, Guanajuato and San Luis Potosí in Mexico. Among the 84 farms included in the trial, 25.3% were in FC (359 animals) fed corn silage, alfalfa hay, and commercial balanced concentrate (18% CP; 500 to 1000g/ head/day); in both extensive (EG) and supplemented (SG) exclusive grazing, vegetation consumed was a mixture of grasses; Bouteloua curtipendula, chloris virgata, bothriochloa saccharoides, leptochloa dubia, rhyncheltythurum roseum, panicum obtusum, bouteluoa repens, aristida adscensionis, setaria parviflora, urochloa fasciulata, pennisetum ciliare., legumes: prosopis leavigata, acacia farnesiana, acacia schaffneri, mimosa biuncifera., shrubs: celtis pallida, psilactis brevilingulata, jatropha dioica, zalazania augusta var. Augusta, verbasina serrata and cactus: opuntia affasiacantha, o. Amyctaea, o. Cretochaeta, o. Hytiacantha, o. Robusta, O. streptacanta, O. tomentosa and O. imbricata Group EG (30%, 426 does) were permanently on rangeland while SG (44.6%, 632 heads) was partially on rangeland supplemented with a commercial balanced feed. Average daily milk yield was significantly (P<0.05) different among groups: 1.6±.212kg (FC), 0.950±.272kg (SG) and 0.720±.153kg (EG). Feeding system also affected milk fatty acid profile, particularly the ω6/ω3 ratio: increasing the amount of concentrate in the diet significantly (P<0.05) improved ω6 or decreased ω3 concentration, together with a rise on antioxidants (polyphenols) under grazing and diminishing when were kept in full confinement. Level of alpha-tocopherol was higher (p<0.05) in grazing goats (193.02μg/100g), compared to SG: 119.83μg/100g and FC: 87.16μg/100g. The degree of antioxidant protection (DAP) increased significantly between treatments, with the highest value being observed in EG (13.2), followed by SG (7.3) and FC (4.1). It is concluded that there is an effect of the feeding system that directly influences the profile of fatty acids and the degree of antioxidant protection in cheese, being greater in milk that comes from grazing goats diminishing beneficial effects for human health. Cheese improved facilities due to farmer incomer, did not significantly affected quality, feeding system seemed to be the key component in the heathy structure of the product.

Keywords: Milk; Grazing; Pufa; Omega Fatty Acids; Antioxidants