Milk production, fatty acid composition and vitamin E content of Payoya goats according to grazing level in summer on Mediterranean shrublands

• Published in: Small ruminant research Vol. 114; no. 1; pp. 167 - 175
• Main Authors: Delgado-Pertíñez, M., Gutiérrez-Peña, R., Mena, Y., Fernández-Cabanás, V.M., Laberye, D.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-08-2013
• Subjects: Antioxidant; antioxidant activity; CLA; conjugated linoleic acid; correlation; Dairy goat; dairy goats; energy requirements; farms; fatty acid composition; grazing; human health; milk production; Milk quality; milk tanks; n-3; omega-3 fatty acids; omega-6 fatty acids; Pasture; polyunsaturated fatty acids; shrublands; summer; vitamin E; whole milk; MUFA; NERG; GLM; SFA; LCFA; Milk quality; n-3; Dairy goat; MG; PUFA; VA; Antioxidant; CP; SCFA; RA; ARA; CT; DPA; MCFA; Pasture; NIR; EPA; TAC; CLA; NER; FA; DHA; ABTS; USFA; HG
• ISSN: 0921-4488; 1879-0941
• DOI: 10.1016/j.smallrumres.2013.06.001

Dietary intake of certain unsaturated fatty acids (FA), in particular conjugated linoleic acid (CLA) and omega-3 FA (n-3 FA), and fat-soluble antioxidants (e.g. α-tocopherol) has been linked to potential health benefits. Nevertheless, there is little information about how Mediterranean shrublands affect the fat composition and fat-soluble antioxidants of milk of dairy goats. The aim of this study was to evaluate the effect during the summer of different grazing levels on Mediterranean scrublands on milk production, milk FA profile and vitamin E content from Payoya goats. Eight farms were selected and data were collected monthly from June to October of 2010. Indicators for feeding management and productivity were obtained. The Percentage of the milking goat's net energy requirements obtained from grazing (NERG) was calculated. Farms were segregated in two groups according to the grazing level: high (HG, n=3) and medium grazing (MG, n=5). Whole milk was collected monthly from bulk tanks of the farms and analyzed for chemical composition, FA profile, α-tocopherol content and total antioxidant capacity (TAC). NERG differed between treatment groups and months (P<0.001 and P<0.05, respectively). No differences between groups were observed for the most studied chemical parameters. The percentages of C16:1 (P<0.01), C18:1 n-9 trans (P<0.05), C18:1 n-9 cis (P<0.05) and MUFA (P<0.01) were significantly higher and the total SFA significantly lower (P<0.01) in milk from MG farms compared with HG farms. In contrast, percentages of the nutritionally desirable FA (α-linolenic acid, C22:5 n-3, total n-3 PUFA) were significantly higher, while levels of total n-6 PUFA and n6:n3 ratio were significantly lower in milk from HG group. In addition, the percentages of NERG were correlated positively with the contents of several n-3 FA and negatively with the n-6 FA and n-6:n-3 ratio. CLA cis-9, trans-11 and CLA trans-10, cis-12 were not affected by grazing level. The short and long-chain FA showed significant variations during the period of study. HG farms showed significant higher α-tocopherol content in September (P=0.030) and October (P=0.025). The TAC levels did not significantly vary according to the grazing level and the month. In conclusions, the high grazing farms showed significantly higher levels of n-3 FA and α-tocopherol compared with the medium grazing farms, which are widely recognized as having beneficial effects on human health.