Effect of naked oats in the dairy cow’s diet on the oxidative stability of the milk fat

Abstract

: Oxidative stability of milk fats from cows o †ered naked oats-and barley-based diets were compared in shelf-life tests using the Schaal Oven Test at 63¡C, and determination of peroxide and thiobarbituric acid values. Milk fat from cows o †ered the diet containing naked oats, although containing a higher proportion of monounsaturated fatty acids, had a signiÐcantly longer oxidation induction period (13 days) than milk fat from cows o †ered the control (barleybased) diet (9 days). However, sensory testing of the milk fats indicated that a perceptible odour di †erence was apparent between stored (63¡C) and unstored milk fats after 3 days of storage irrespective of the diet fed. It is possible that the odours perceived may have originated from the cowsÏ diets or from hydrolytic rancidity reactions. The difficulties of relating chemical and sensory testing of the oxidative deterioration of milk fat or butter are underlined.1998 SCI. ( J Sci Food Agric 76, 546È552 (1998)

Effect of level of oil inclusion in the diet of dairy cows at pasture on animal performance and milk composition and properties

“…Although oxidative stability of the milk fats varied over the trial period, the treatment milk fats were not significantly different ( P > 0.05) from the control milk fats at any point in time. This result was in agreement with previous work with high‐oleic milk fat by Fearon et al 28 and was in line with the observations of Sonntag35 on the relative oxidation rates of saturated fatty acids/MUFA/PUFA.…”

“…However, notwithstanding dietary fatty acid composition, other factors related to diet may also influence milk fat composition, eg blood serum insulin levels and their possible link to mammary gland fatty acid synthesis 36. It must be concluded, therefore, that the stage of lactation responses observed in this study and previously28 were mediated by a combination of factors related to milk and milk fat synthesis, and animal response did not derive solely from the cow's lactational cycle.…”

“…However, over the trial period, late‐lactation cows consistently produced milk fats containing a significantly ( P < 0.001) higher proportion of unsaturated fatty acids than the mid‐lactation animals. A stage of lactation effect was also noted between early‐ and mid‐lactation animals by Fearon et al 28 They reported that pre‐trial differences in proportions of saturated and unsaturated fatty acids in milk fat from groups of early‐ and mid‐lactation dairy cows were also present in the milk fat compositional changes that were achieved during a subsequent trial in which a ration containing naked oats was offered.…”

“…Parallel measurements of solid fat content were made at 5, 10, 15, 20 and 25 °C after tempering of the milk fat for 30 min at the measuring temperature. The oxidative stabilities of the milk fats were compared by employing the Schaal oven test at 63 °C to accelerate oxidation and assessing oxidation by measurement of peroxide value (PV) (AOCS method Cd 8–53) 26, 28. The time taken to reach a PV of 10 meq kg −1 fat was used for comparison of oxidation rates of the milk fats.…”

Molecular Gastronomy: A New Emerging Scientific Discipline

“…In Northern countries where cattle are generally kept indoors and fed on hay, winter cheeses and butter made from winter milk are whiter than products made from summer milk, when the cows have been on pasture. 77,78 …”