Milk Fatty Acid Composition of Cows Fed a Total Mixed Ration or Pasture Plus Concentrates Replacing Corn with Fat

Abstract

Thirty-one Holstein cows (six ruminally cannulated) were used to evaluate milk fatty acids (FA) composition and conjugated linoleic acid (CLA) content on three dietary treatments: 1) total mixed rations (TMR), 2) pasture (Avena sativa L.) plus 6.7 kg DM/d of corn-based concentrate (PCorn), and 3) pasture plus PCorn with 0.8 kg DM/d of Ca salts of unsaturated FA replacing 1.9 kg DM/d of corn (PFat). No differences were found in total (22.4 kg/d) or pasture (18.5 kg/d) dry matter intake, ruminal pH, or total volatile fatty acids concentrations. Fat supplementation did not affect pasture neutral detergent fiber digestion. Milk production did not differ among treatments (19.9 kg/d) but 4% fat-corrected milk was lower for cows fed the PFat compared to cows fed the TMR (16.1 vs. 19.5 kg/d) primarily because of the lower milk fat percentage (2.56 vs. 3.91%). Milk protein concentration was higher for cows fed the TMR than those on both pasture treatments (3.70 vs. 3.45%). Milk from the cows fed the PCorn had a lower content of short- (11.9 vs. 10.4 g/100 g) and medium-chain (56.5 vs. 47.6 g/100 g) FA, and a higher C18:3 percentage (0.07 vs. 0.57 g/100 g) compared with TMR-fed. Cows fed the PFat had the lowest content of short- (8.85 g/100 g) and medium-chain (41.0 g/100 g) FA, and the highest of long-chain FA (51.4 g/100 g). The CLA content was higher for cows in PCorn treatment (1.12 g/100 g FA) compared with cows fed the TMR (0.41 g/100 g FA), whereas the cows fed the PFat had the highest content (1.91 g/100 g FA). Pasture-based diets increased the concentrations of long-chain unsaturated FA and CLA in milk fat. The partial replacement of corn grain by Ca salts of unsaturated FA in grazing cows accentuated these changes. However, those changes in milk FA composition were related to a depression in milk fat.

Winter feeding systems and dairy cow breed have an impact on milk composition and flavour of two Protected Designation of Origin French cheeses

“…The effect of diet on the FA profile is consistent with the literature (Chilliard et al, 2001;Hurtaud et al, 2002;Schroeder et al, 2003;Couvreur et al, 2006a and. The large increase in C18:1 is probably due to a greater mobilization of the lipidic reserves with the LowGS diet (Chilliard et al, 2001).…”

The effects of supplementation with sunflower and soybean oils on the fatty acid profile of milk fat from grazing dairy cows

“…The concentration of oleic acid and its different cis/trans isomers (including trans-10 C 18:1 ) significantly (P < 0.05) increased in the milk fat of cows supplemented with VO as a likely consequence of the rumen biohydrogenation process of linoleic and linolenic FA present in the diet and due to the desaturation of stearic acid in the mammary gland [4]. These results are globally supported by data reviewed by Schroeder et al [17] and by the works of Murphy et al [11], Lawless et al [9], Vidaurreta et al [20] and Schroeder et al [16], leaving cows feeding on pasture. All these authors used oleaginous seeds treated or not, or calcium salts of fatty acids (CaFA), which provide a reduced degree of protection of long chain unsaturated fatty acids to the biohydrogenation in the rumen.…”

“…Despite the fact that the oils used in this study were good sources of linoleic acid, its increase in milk fat of supplemented cows, though statistically significant (P < 0.05), was low, suggesting a modest transfer efficiency of this fatty acid from vegetable oils to milk fat and a high rate of rumen biohydrogenation. Using fullfat rapeseeds (FFS), full-fat soybeans (FFR) or CaFA which provide some protection from rumen biohydrogenation, other authors observed a two fold increase in linoleic acid concentration in milk fat of grazed cows (4.9 g·100 g -1 FA) [9,11,16]. Unlike what happens with diets composed of conserved forage and variable proportions of concentrates, there is less information in the literature concerning the effect of oils or vegetable seed supplementation of diets on the concentrations of CLA and TVA in the milk fat of grazing dairy cows.…”

“…Stanton et al [18] and Lawless et al [9] reported significant increases in the concentrations of CLA and TVA in the milk fat of grazing cows directly related to the amount of FFS and FFR supplemented, which were supported by the results of the present study. Partially replacing maize grain by CaFA in the concentrate supplemented to grazing dairy cows, increased the CLA content in milk fat by 58% [20] and by 173% [16]. The oil source, despite a slight difference in FA composition, did not significantly influence the CLA content of milk fat (Tab.…”

Partial replacement of corn grain with calcium salts of fatty acid in the concentrate fed to grazing primiparous and multiparous dairy cows

“…The uptake of some specific preformed FA (e.g., trans-10, cis-12 clA and trans-8, cis-10 CLA) reduce the activity and/or expression of genes that encode important enzymes involved in uptake, synthesis and desaturation of FA in the mammary gland (Chilliard et al 2000). In a previous study using the same source of cSFA fed to grazing cows, milkfat concentration was reduced (-26% in respect to the Control group) with no negative effect on NDF digestion (Schroeder et al 2003). In pasture-fed MC, milkfat concentration was decreased 43% by the abomasal infusion with 40 g day -1 of a clA mixture, reducing the energy requirements for lactation (13%) and increasing milk yield (11%; Mackle et al 2003).…”