Effect of lecithins partly replacing rumen-protected fat on fatty acid digestion and composition of cow milk

Effects of abomasal infusion of soybean or sunflower phospholipids on nutrient digestibility and milk production in lactating dairy cows

The fatty acid (FA) and phospholipid composition of dietary lecithin may influence FA digestibility and milk production in cattle. Eight multiparous Holstein cows (99.4 ± 9.2 d in milk [DIM]; 48.9 ± 3.8 kg milk/d) were enrolled in a 3 × 3 incomplete Latin square design with 3 treatments provided as continuous abomasal infusates spanning 14-d experimental periods: water (CON), soybean phospholipids (SOY; 74.5 g of deoiled soy lecithin), or sunflower phospholipids (SUN; 133.5 g of hydrolyzed sunflower lecithin). Cows were fed the same diet, which contained (% dry matter) 27.0% neutral detergent fiber (NDF), 15.6% crude protein (CP), 26.2% starch, and 5.87% FA. Treatments did not modify body weight, milk fat, protein, or lactose contents, or the efficiency of producing energy-corrected milk. Cows infused with SUN had greater milk yields than those receiving SOY or CON treatments. Cows infused with SUN had higher total solids, protein, and lactose yields than cows receiving the SOY or CON treatments. Sunflower phospholipids enhanced feed efficiency (milk yield/dry matter intake) relative to SOY or CON. Treatment did not affect intakes or apparent total-tract digestibilities for NDF, CP, starch, or 16-carbon (16C) FA. Cows receiving SUN had greater total FA and 18-carbon (18C) FA intakes than SOY or CON, but treatments did not impact their digestibility. Milk FA composition was modified by treatment. Cows receiving SUN had a greater concentration of polyunsaturated FA and lower concentrations of saturated FA and monounsaturated FA in milk relative to SOY or CON. In conclusion, the abomasal infusion of SUN improved milk production and milk FA composition, indicating potential benefits for dairy cow nutrition and milk quality.

Evaluation and quantification of associations between commonly suggested milk biomarkers and the proportion of grassland-based feeds in the diets of dairy cows

This study is a first step approach towards the prediction of the proportion of grassland-based feeds (%GB) in dairy cow diets with the aid of three different groups of milk biomarkers. We aimed to evaluate and quantify the associations between biomarkers commonly suggested in the literature and %GB in individual cows as a hypothesis-generating stage for the prospective establishment of accurate %GB prediction models. Consumers and governments financially encourage sustainable, local milk production making grass-based feeding, in grassland-dominated regions, of major interest. Milk from grassland-fed cows differs from that of other feeding systems by inferential fatty acids (FA), β-carotene content and yellow color; however, these biomarkers have not been evaluated together for their association with %GB. Using approved methods of parametric regression analysis, gas chromatography (GC), mid-infrared spectra (MIR) and color spectroscopy, we aimed to develop a first step towards an easy-to-implement, cost-effective milk-based control to estimate %GB in dairy cow diets. The underlying database was generated with 24 cows each fed one of 24 different diets gradually increasing in grass silage and decreasing in corn silage. Our results indicate that GC-measured α-linolenic acid, total n-3 FA and the n-6:n-3 ratio, MIR-estimated PUFA and milk red-green color index a* are robust milk biomarkers for constructing accurate prediction models to determine %GB. Based on simplified regression analysis, diets containing 75% GB should contain ≥ 0.669 and 0.852 g α-linolenic acid and total n-3 FA per 100 g total FA, respectively, and an n-6:n-3 FA ratio of < 2.02 measured with GC; estimated with MIR, polyunsaturated FA should be ≥ 3.13 g/100 g total FA. β-carotene was not a good predictor for estimating %GB. Unexpectedly, the milk became greener with increasing %GB (negative a* values, ‒6.416 for 75% GB), suggesting the red-green color index, not yellow-blue, as a suitable biomarker.

Effects of dietary deoiled soy lecithin supplementation on milk production and fatty acid digestibility in Holstein dairy cows

Deoiled soy lecithin is a feed additive enriched in phospholipids. Our study evaluated the effects of dietary deoiled soy lecithin supplementation on (1) milk production and composition, (2) plasma and milk fatty acid (FA) content and yield, and (3) apparent FA digestibility and absorption in lactating dairy cows fed fractionated palm fat. In a split-plot Latin square design, 16 Holstein cows (160 ± 7 days in milk; 3.6 ± 1.2 parity) were randomly allocated to a main plot receiving a corn silage and alfalfa haylage-based diet with palm fat containing either moderate (MPA) or high palmitic acid (HPA) content at 1.75% of ration dry matter (72 or 99% palmitic acid, respectively; n = 8/palm fat diet). On each palm fat diet, deoiled soy lecithin was top-dressed at 0, 0.12, 0.24, or 0.36% of ration dry matter in a replicated 4 × 4 Latin square design. Following a 14-d covariate period, lecithin supplementation spanned 14 d, with milk and blood collected during the final 3 d. Milk composition and pooled plasma markers were measured. The statistical model included the fixed effects of palm fat type, lecithin dose, period, and the interaction between palm fat type and lecithin dose. The random effect of cow nested within palm fat group was also included. Lecithin linearly decreased dry matter intake. In cows fed HPA, lecithin feeding reduced milk fat content and tended to decrease milk fat yield. Although no changes in milk yield were observed, a quadratic reduction in 3.5% fat-corrected milk was observed with increasing lecithin dose. Lecithin linearly increased energy-corrected milk efficiency in cows fed MPA. Lecithin supplementation also decreased milk urea nitrogen, relative to unsupplemented cows. The proportion of 16-carbon FA in milk fat decreased linearly with lecithin dose, whereas 18-carbon FA increased linearly. Lecithin reduced de novo FA (<16-carbon) content and tended to increase preformed FA (>16-carbon) content in a linear manner. Compared with MPA, HPA diets reduced apparent total and 16-carbon FA digestibility and absorption. Deoiled soy lecithin feeding did not modify FA digestibility or absorption. Our observations suggest that soy lecithin feeding modifies rumen digestion to reduce dry matter intake and change milk composition.

Methane Emissions and Milk Fatty Acid Profiles in Dairy Cows Fed Linseed, Measured at the Group Level in a Naturally Ventilated Housing and Individually in Respiration Chambers

Simple Summary

Cows emit the greenhouse gas methane (CH₄) as a result of microbial feed digestion. Methane emissions can be reduced by adopting nutritional strategies, such as dietary supplementation of linseed. Additionally, the oil in linseed increases the proportion of favorable fatty acids in milk fat. This study evaluated the effect of linseed on CH₄ emission and milk fatty acid composition measured in a group of cows in a naturally ventilated barn and in individual cows in respiration chambers. The substantially higher proportions of favorable fatty acids in the milk of linseed-fed cows were detected in individual milk samples and in the milk of the herd. Therefore, the analysis of bulk milk could be a suitable control instrument for retailers. Visualizing the course of CH₄ emissions over a whole day showed slightly lower CH₄ values in linseed-supplemented individuals and groups. However, we found no significant reduction of CH₄ as a result of linseed supplementation. Feed supplements in concentrations that are effective in reducing CH₄ must show whether the reduction potential is comparable when determined at the group and individual levels.

Abstract

The present study evaluated the effects of linseed supplementation on CH₄ emission and milk fatty acid composition in dairy cows measured at the group level in an experimental dairy loose housing using a tracer gas technique and individually in tied stalls and respiration chambers. Cows (2 × 20) were maintained in two separate sections under loose-housing conditions and received a diet supplemented with extruded linseed (L) lipids (29 g·kg⁻¹ dry matter) or a control (C) diet containing corn flour. Subsequently, 2 × 6 cows per dietary group were investigated in a tied-housing system and respiration chambers. Substantially higher proportions of favorable milk fatty acids were recovered in L cows when compared with C cows at the group level, making the analysis of bulk milk a suitable control instrument for retailers. Linseed supplementation resulted in a slightly lower diurnal course of CH₄ emission intensity than the control at the group and individual levels. However, we found no more than a trend for a CH₄ mitigating effect, unlike in other studies supplementing similar linseed lipid levels. Feed supplements in concentrations that lead to a significant reduction in CH₄ emissions must show whether the reduction potential determined at the group and individual levels is comparable.

Flowering catch crops used as forage plants for dairy cows: influence on fatty acids and tocopherols in milk

The effect of several flowering dicotyledonous catch crop plants (dicots) on milk fat quality in cows was investigated to test the hypothesis that their phenolic compounds may inhibit ruminal biohydrogenation and thus enhance the transfer to milk of intact, plant-derived polyunsaturated fatty acids. Berseem clover (Trifolium alexandrinum), buckwheat (Fagopyrum esculentum), and phacelia (Phacelia tanacetifolia) were sown in mixture with ryegrass (Lolium multiflorum; intended biomass proportion of 0.2) on 1ha. For comparison, nonflowering chicory (Cichorium intybus, also sown in mixture with ryegrass) and pure ryegrass were cultivated. Realized biomass proportions (wet weight) were 91% for berseem clover, 69% for buckwheat, 54% for phacelia, and 51% for chicory. At the start of flowering (or from d 47 after sowing onward), cultures were harvested daily and fed for 20 d ad libitum to groups of 6 midlactation cows each. Additionally, 1 kg each of energy and protein concentrate and pure ryegrass hay were fed. Individual intake and milk yield of the cows were measured daily. Milk samples were obtained twice daily 5 d before and from 11 to 20 d after the start of treatment feeding. Feed samples were drawn twice a week from the fresh feeds. Apart from standard traits, feeds and milk were analyzed for fatty acids, tocopherols, and phenolic fractions. Only a few substantial treatment effects on intake and performance were observed. All diets based on dicots increased α-linolenic acid (ALA) concentrations in milk fat compared with the ryegrass diet even though the corresponding swards were not generally richer in ALA. The highest ALA concentration in milk fat (1.3 g/100g of fatty acids) occurred with the berseem clover diet. Transfer rate of ALA from feed to milk was highest with the buckwheat diet (0.09) and lowest with ryegrass (0.05). This was congruent with the differences in total extractable phenols, being high in the buckwheat sward (2.6% of dry matter) and low in the ryegrass sward (1.2% of dry matter). Intermediates of ALA biohydrogenation were lowest in the milk fat of the buckwheat group, indicating an inhibitory effect of this treatment, which provided the highest dietary levels of phenols. The α-tocopherol concentration in milk was higher with the buckwheat diet than with berseem clover and phacelia diets. The study provides evidence that the ALA concentration in milk fat could be enhanced by feeding flowering dicots; however, this was due to different modes of action.

Milk fatty acid profile of Peruvian Criollo and Brown Swiss cows in response to different diet qualities fed at low and high altitude

Two identical experimental protocols were followed at 200 and 3,600 m above sea level (a.s.l.) determining the changes of the milk fatty acid (FA) profile of Brown Swiss (BS) and indigenous Peruvian Criollo cows (CR) as a response to diets which were designed to cover the variation in feed quality caused by season. At each site (altitude), six BS and six CR cows, adapted to > 3,500 m a.s.l., were fed three dietary treatments (DS, dry-season forage; RS rainy-season forage; OC, diet optimised to meet the cow's requirements) in a 2 x 2 x 3-factorial arrangement. Intakes of FA and milk yield increased from diet DS (low quality diet) to RS and OC (high quality diet) for both cow types. Milk fat proportions of conjugated linoleic acid (CLA), C18:3 c9,c12,c15, total n-3 and polyunsaturated FA (PUFA) were highest (p < 0.05) with diet OC and higher in the lowlands than in the highlands. Low intakes of diet DS obviously resulted in a ruminal energy deficiency and body lipid mobilisation. The ruminal energy deficiency with diet DS was especially pronounced in BS, apparently reducing biohydrogenation rate and leading to lower proportions of C18:0 and higher proportions of C18:3 c9,c12,c15 in milk fat (p < 0.05). Especially C18:3 c9,c12,c15 intake did not concur with its proportion in milk fat, suggesting a strong dependence on energy status. Milk yield and FA excretion with milk were higher for BS than for CR (p < 0.05) with all three diets although milk fat content was lower (p < 0.05) for BS than CR. Milk fat of BS was richer in CLA and PUFA than milk fat of CR (p < 0.05). The desaturase indices for 18 FA were also higher for BS than CR (p < 0.05), suggesting a slightly higher delta9-desaturase activity for BS, especially with diet DS. Milk fat content was generally higher at the high altitude than at the lowland site (p < 0.05), whereas the FA profile was unexpectedly similar across sites. Various interactions were found among diet type, cow type and altitude (site) indicating that a combination of these factors contributes to the characteristic FA profile of the respective milk.

Significance of coprophagy for the fatty acid profile in body tissues of rabbits fed different diets

Four groups of eight New Zealand hybrid rabbits were fattened with ad libitum access to the following pelleted experimental diets: ryegrass meal or alfalfa meal fed either alone or with oats meal in a ratio of 1:1. After 25 weeks they were slaughtered and dissected. Fatty acid (FA) profiles of caecotrophs (re-ingested fermentation products of the caecum), perirenal adipose tissue and intramuscular fat in the Musculus quadriceps were determined. With high proportions of branched-chain FA (BFA) and trans FA, and increased proportions of saturated FA relative to the diets, the caecotroph FA profile showed a clear fingerprint of anaerobe microbial lipid metabolism including biohydrogenation. By contrast, the FA profiles of adipose and lean tissue comprised high proportions of polyunsaturated FA (PUFA), whilst BFA and trans FA occurred in much lower proportions compared to the caecotrophs. Thus, coprophagy did not substantially modify the FA composition of the tissues investigated. Use of forage-only diets, compared to the oats supplemented diets, led to extraordinary high proportions of n-3 PUFA (including 18:3 and long-chain n-3) in the fat of adipose (21.3 vs. 6.7%) and lean tissue (15.4 vs. 5.7%). The forage type diet (grass vs. alfalfa) had smaller effects on the FA profiles. Indications of diet effects on endogenous desaturation, chain elongation and differential distribution of functional FA between the two tissues investigated were found.

A study on the causes for the elevated n-3 fatty acids in cows' milk of alpine origin

The influence of grass-only diets either from rye-grass-dominated lowland pastures (400 m above sea level) or botanically diverse alpine pastures (2000 m) on the FA profile of milk was investigated using three groups of six Brown Swiss cows each. Two groups were fed grass-only on pasture (P) or freshly harvested in barn (B), both for two experimental periods in the lowlands and, consecutively, two periods on the alp. Group C served as the control, receiving a silage-concentrate diet and permanently staying in the lowlands. Effects of vegetation stage or pasture vs. barn feeding on milk fat composition were negligible. Compared with the control, alpha-linolenic acid (18:3n-3) consumption was elevated in groups P and B (79%; P< 0.001) during the lowland periods but decreased on the alp to the level of C owing to feed intake depression and lower 18:3n-3 concentration in the alpine forage. Average 18:3n-3 contents of milk fat were higher in groups P and B than in C by 33% (P< 0.01) at low and by 96% (P < 0.001) at high altitude, indicating that 18:3n-3 levels in milk were to some extent independent of 18:3n-3 consumption. The cis-9, trans-11 CLA content in milk of grass-fed cows was higher compared with C but lower for the alpine vs. lowland periods whereas the trans-11, cis-13 isomer further increased with altitude. Long-chain n-3 FA and phytanic acid increased while arachidonic acid decreased with grass-only feeding, but none of them responded to altitude. Grass-only feeding increased milk alpha-tocopherol concentration by 86 and 134% at low and high altitude (P < 0.001), respectively. Changes in the ruminal ecosystem due to energy shortage or specific secondary plant metabolites are discussed as possible causes for the high 18:3n-3 concentrations in alpine milk.

Digestive and metabolic utilization of lauric, myristic and stearic acid in cows, and associated effects on milk fat quality

In an experiment with 3 x 6 Brown Swiss cows, the effects of dietary supplementations (40 g/kg) of non-esterified lauric (12 : 0), myristic (14 : 0) and stearic acid (18 : 0) on digestibility, metabolisability, milk fat composition and melting properties were investigated. The diet consisted of forage and concentrate in a ratio of 3 : 2. Cows were fed the C18 : 0 supplemented diet for 10 days before treatment feeding started for a 15-day experimental period where, at the end, excreta were quantitatively collected and gaseous exchange was measured. The DM intake averaged 17.9 kg/d for the C14 : 0 and C18 : 0 diets and was reduced (P < 0.05) by 18% in the C12 : 0 diet. The realised intakes of total C12 : 0, C14 :0 and C18 : 0 amounted to 368, 391 and 617 g/d in the respective groups. The efficiency of ME utilization for lactation was higher (P < 0.001) in the C12 : 0 group than in the two other groups indicating differences in metabolism of C12 : 0 in comparison with C14 : 0 and C18 : 0. Shifts in dietary fatty acid supplementation were clearly reflected in the milk fat composition. Associated changes were elevated CLA and C18 : 1 trans when supplementing C12 : 0, and a high C18 : 1 to C16 : 0 ratio (P < 0.05) in the C12 : 0and C18 : 0 groups which resulted in an easier melting milk fat than with supplementary C14 : 0. Despite certain favourable effects of C12 : 0 in metabolic energy utilization and milk fat melting properties (relative to C14 : 0), more research is needed on how to improve its palatability for dairy cows.