Relationship Among Trans and Conjugated Fatty Acids and Bovine Milk Fat Yield Due to Dietary Concentrate and Linseed Oil

Abstract

Effects on fatty acid profiles and milk fat yield due to dietary concentrate and supplemental 18:3n-3 were evaluated in 4 lactating Holstein cows fed a low- (35:65 concentrate:forage; L) or high- (65:35; H) concentrate diet without (LC, HC) added oil or with linseed oil (LCO, HCO) at 3% of DM. A 4 x 4 Latin square with four 4-wk periods was used. Milk yield and dry matter intake averaged 26.7 and 20.2 kg/d, respectively, across treatments. Plasma acetate and beta-hydroxybutyrate decreased, whereas glucose, nonesterified fatty acids, and leptin increased with high-concentrate diets. Milk fat percentage was lower in cows fed high-concentrate diets (2.31 vs. 3.38), resulting in decreases in yield of 11 (HC) and 42% (HCO). Reduced yields of 8:0-16:0 and cis9-18:1 fatty acids accounted for 69 and 17%, respectively, of the decrease in milk fat yield with HC vs. LC (-90 g/d), and for 26 and 33%, respectively, of the decrease with HCO vs. LCO (-400 g/d). Total trans-18:1 yield increased by 25 (HCO) and 59 (LCO) g/d with oil addition. Trans10-18:1 yield was 5-fold greater with high-concentrate diets. Trans11-18:1 increased by 13 (HCO) and 19 (LCO) g/d with oil addition. Trans13+14-18:1 yield increased by 9 (HCO) and 18 (LCO) g/d with linseed oil. Yield of total conjugated linoleic acids (CLA) in milk averaged 6 g/d with LC or HC compared with 14 g/d with LCO or HCO. Cis9,trans11-CLA yield was not affected by concentrate level but increased by 147% in response to oil. Feeding oil increased yields of trans11,cis13-, trans11,trans13-, and trans,trans-CLA, primarily with LCO. Trans10,cis12-CLA yield (average of 0.08 g/d) was not affected by treatments. Yield of trans11,cis15-18:2 was 1 g/d in cows fed LC or HC and 10 g/d with LCO or HCO. Yields of cis9,trans11-18:2, cis9,trans12-18:2, and cis9,trans13-18:2 were positively correlated (r = 0.74 to 0.94) with yields of trans11-18:1, trans12-18:1, and trans13+14-18:1, respectively. Plasma concentrations of biohydrogenation intermediates with concentrate or linseed oil level followed similar changes as those in milk fat. Milk fat depression was observed when HC induced an increase in trans10-18:1 yield. A correlation of 0.84 across 31 comparisons from 13 published studies, including the present one, was found among the increase in percentage of trans10-18:1 in milk fat and decreased milk fat yield. We observed, however, more drastic milk fat depression when HCO increased yields of total trans-18:1, trans11,cis15-18:2, trans isomers of 18:3, and reduced yields of 18:0 plus cis9-18:1.

Conjugated linolenic acid (CLnA), conjugated linoleic acid (CLA) and other biohydrogenation intermediates in plasma and milk fat of cows fed raw or extruded linseed

“…Because of their lower proportion in milk fat and because of the lower milk fat production, the daily amount of short-chain FA was decreased with linseed diets: the total output of 8:0-14:0- saturated even-chain FA was 315, 258 and 211 g/day with diets C, RL and EL, respectively (P , 0.001 for both contrasts C v. linseed and RL v. EL), which represented a 18% and 33% decrease, respectively, and explained the reduction of milk fat yield. With raw linseed, Gonthier et al (2005) reported a 38% decrease of 8:0-14:0 daily output, and a 34% decrease was observed due to linseed oil (Loor et al, 2005). Similar effect was observed after soybean (Chouinard et al, 1997) or sunflower (Schingoethe et al, 1996) dietary addition.…”

“…Among possible reasons for this inhibition, Grummer (1991) cited a direct inhibition of mammary acetyl-CoA carboxylase, which is mediated by trans-10, cis-12 18:2 (Baumgard et al, 2000), but in our experiment, milk proportion of trans-10, cis-12 18:2 was very low with all diets. Loor et al (2005) suggested that milk fat depression could also be explained by other FA, including trans-10 18:1, which exhibited high proportions in milk with low proportions of 6:0-14:0 in our experiment. However, Lock et al (2007) recently demonstrated that this FA does not reduce milk fat synthesis in dairy cows.…”

“…Higher proportions of other BH intermediates, particularly trans-11, cis-15 18:2 and trans-6-trans-11 18:1, were found in plasma and milk after linseed oil supplementation (Loor et al, 2005). On the contrary, little is known about the concentration of CLnA in milk (Destaillats et al, 2005), and the effects of diet on this FA have not been studied.…”

“…Among oilseeds, linseed has the highest proportion of cis-9, cis-12, cis-15 18:3, and also contains cis-9, cis-12 18:2, so that the addition of linseed to the diet of dairy cows could improve PUFA and conjugated FA contents in milk fat; higher proportions of cis-9, cis-12, cis-15 18:3 and CLA have been observed in plasma and milk fat after the dietary addition of linseeds or linseed oil (Gonthier et al, 2005;Loor et al, 2005). Higher proportions of other BH intermediates, particularly trans-11, cis-15 18:2 and trans-6-trans-11 18:1, were found in plasma and milk after linseed oil supplementation (Loor et al, 2005).…”

Foetal bovine intermuscular adipose tissue exhibits histological and metabolic features of brown and white adipocytes during the last third of pregnancy

“…Breed 3 age interactions were considered significant at P < 0.10 to guard against type-II error. This was deemed appropriate because of the low number of experimental animals tested for interaction rather than main effects, and the a priori expectation on interactions (Loor et al, 2005).…”