-The objective of this study was to observe the effect of supplementation with vegetable oils (VO) on the fatty acid profiles and conjugated linoleic acid (CLA) content of milk fat. Twelve dairy cows in mid lactation fed on pasture were blocked by body weight, milk production and days in lactation and randomly allocated from blocks to 3 treatments repeated in a Latin square design with periods of 28 day duration. The treatments were as follows: cows on pasture supplemented with 5 kg concentrate per head per day (C), supplemented with 4.5 kg concentrate + 0.5 kg sunflower oil per head per day (SFO) and supplemented with 4.5 kg concentrate + 0.5 kg soybean oil per head per day (SBO). The animals were grazed as a group and were stocked at 2.5 heads per hectare. The treatments had no effect on milk yield or protein yield and content, but decreased milk fat yield and content (P < 0.05). Milk fat from the cows supplemented with VO had a lower concentration of short and medium chain fatty acids (P < 0.05) and a higher concentration of long chain fatty acids (P < 0.05). The addition of VO to the diet also resulted in a reduction in saturated and an increase in unsaturated fatty acids of milk fat (P < 0.05). The hypercholesterolemic fatty acids in milk fat (i.e. C12:0, C14:0 and C16:0) decreased while the concentration of oleic and linoleic acids increased with VO (P < 0.05). There was no effect on linolenic acid. Finally, the inclusion of VO in the diet increased (P < 0.05) the contents in milk fat of the various cis/trans isomers of oleic acid (including trans-vacenic, TVA) and of CLA which increased by 61%. dairy cow / conjugated linoleic acid / fatty acids / pasture / vegetable oils Résumé -Effet de la supplémentation du régime avec de l'huile de tournesol ou de soja sur la composition en acides gras du lait chez la vache laitière au pâturage. L'objectif de cette étude était d'observer l'effet de la supplémentation du régime en huiles végétales sur le profil des acides gras et la teneur en acide linoléique conjugué (CLA) dans les matières grasses du lait. Douze vaches laitières, en milieu de lactation et au pâturage, ont été mises en lot selon le poids vif, la production * Corresponding author: orego@angra.uac.pt laitière et le stade de lactation. Elles ont été réparties au hasard en lots, et trois traitements ont été testés selon un dispositif en carré latin 3 × 3 sur des périodes de 28 jours. Les traitements ont été les suivants : vaches au pâturage supplémentées avec 5 kg de concentré par bovin par jour (C), supplémentées avec 4,5 kg de concentré + 0,5 kg d'huile de tournesol (SFO) et supplémentées avec 4,5 kg de concentré + 0,5 kg d'huile de soja (SBO). Les animaux ont été conduits en groupe avec un chargement de 2,5 bovins à l'hectare. La supplémentation n'a eu aucun effet sur la production de lait, de protéines et le taux protéique du lait. En revanche, elle a significativement diminué la production de matières grasses et le taux butyreux du lait (P < 0,05). L'addition d'huiles végétales a eu pour cons...
Meat from lambs finished with high-starch diets often contains low concentration of vaccenic (t11-18:1) and rumenic (c9,t11-18:2) acids and high concentration of t10-18:1. We hypothesized that replacing cereals by dehydrated citrus pulp (DCP) and the inclusion of tanniferous feed sources in oil supplemented diets might reduce the accumulation of t10-18:1 and increase the t11-18:1 and c9,t11-18:2 in lamb meat, without affecting the productive performance. In total, 32 lambs were assigned to four diets which combine two factors: basal diet (BD) (cereals v. DCP) and Cistus ladanifer (CL) (0 v. 150 g/kg dry matter). Feed intake, average daily weight gain and carcass traits were not affected by treatments, except for dressing percentage that was reduced with DCP (P=0.046). Both DCP and C. ladanifer reduced tenderness and juiciness of meat, and C. ladanifer also reduced (P0.05) by diets. However, DCP increased the proportions of odd-chain FA (P=0.005) and several minor biohydrogenation (BH) intermediates in meat lipids. C. ladanifer had few effects on meat FA profile. The proportions of t11-18:1 and c9,t11-18:2 were high in all diets (5.4% and 1.5% of total FA, respectively) and were not influenced by the treatments. Basal diet and CL showed some significant interactions concerning FA composition of intramuscular fat. In diets without C. ladanifer, replacement of cereals by DCP increased the 18:0 (P<0.05) and decreased t10,c12-18:2 (P<0.05), t10-18:1 (P<0.10) and t10-/t11-18:1 ratio (P<0.10) with a large reduction of the individual variation for t10-18:1 and of t10-/t11-18:1 ratio. Combined with cereals, C. ladanifer increased 18:0 and reduced the BH intermediates in meat. Replacement of cereals by DCP seems to promote a more predictable FA profile in lamb meat, reducing the risk of t10-shifted BH pathways in the rumen.
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