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1417
Alternative forage crops modify the composition and content of bovine milk fatty acids
Bioactive fatty acids (FA) found in milk have been linked to human health benefits. Alternative forage crops (AFC) include small grains, warm-season grasses and legumes that can potentially enhance forage production. The objective of this study was to determine if traditional pasture strip-tilled with AFC (treatment, TRT) would alter the composition (g/100g FA) and content (g/kg milk) of milk FA compared with traditional grass-legume pasture (control, CON). Two 21-d experiments, spring (SPR) and summer (SUM), were conducted using 16 lactating Jersey cows (SPR, 85 ± 46 DIM; SUM, 143 ± 58 DIM). Cows were divided into two groups and offered 60% TMR (DM basis) and 40% pasture as AFC or traditional. SPR AFC included barley, wheat, rye, triticale, and hairy vetch (2.4% diet DM), while SUM AFC included buckwheat, chickling vetch, and oat (10.0% diet DM). From d 19-21 of each experiment, milk samples were collected during four consecutive milkings. Forage and milk FA were analyzed via gas-liquid chromatography. Differences between least-squares means were evaluated using the student’s t test (JMP Pro 12). SPR forage FA (% total) included CON (total n-3 FA: 30.1%; total n-6 FA: 35.2%) and TRT (total n-3 FA: 46.2%; total n-6 FA: 21.5%), whereas the SUM forage FA included CON (total n-3 FA: 44.4%; total n-6 FA: 22.6%) and TRT (total n-3 FA, 45.7%; total n-6 FA, 22.0%). No differences in the milk content of total PUFA, branched-chain FA, or biohydrogenation intermediates (e.g., trans-11 18:1) were observed in either experiment. Milk proportions of total odd-chain FA were higher (P<0.01) in SPR TRT (2.07 g/100 g) than in SPR CON (1.96 g/100 g). Milk proportions of n-3 FA and trans-18:1 were respectively lower (P<0.01) in SPR TRT (0.64 g/100g; 20.5 g/100 g) than in SPR CON (0.71 g/100g; 22.8 g/100 g), but the contents of these FA were not different between groups. Milk content of 12:0 was higher (P < 0.05) in SPR TRT (1.86 g/kg milk) than in SPR CON (1.56 g/kg milk) (P <0.05). Total milk SFA content was higher (P<0.05) in SUM TRT (33.7 g/kg) than in SUM CON (29.1 g/kg). Milk content of de novo FA (CON: 11.6 g/kg milk; TRT: 13.2 g/kg milk) and mixed FA (CON: 13.0 g/kg milk; TRT: 16.2 g/kg milk) were higher (P<0.01) in SUM AFC-fed cows. In conclusion, AFC altered the composition and content of milk FA.
Keywords: dairy, organic, pasture