Acid Composition Of Dairy Cows Research Articles

Associations between Dietary Fatty Acid Profile and Milk Fat Production and Fatty Acid Composition in Dairy Cows: A Meta-Analysis.

This meta-analysis aimed to investigate the effect of dietary fatty acid (FA) profile on milk fat production and FA profile in dairy cows. The study also aimed to develop prediction models using a meta-regression approach. The database included 217 peer-reviewed articles on lactating dairy cows (n = 12,892), consisting of 515 treatment means. Effect size was assessed using the raw mean differences between diets with supplementary lipid sources and those without. Subgroup analyses were employed to assess heterogeneity. Diets rich in saturated FA (SFA) increased milk fat production and proportion, while reducing de novo FA in milk. Diets high in monounsaturated FA and polyunsaturated FA decreased mixed FA in milk. Most lipid-supplemented diets increase preformed FA in milk, except those rich in SFA. Prediction models were developed using meta-regression. Key predictors of milk fat production included neutral detergent fiber (NDF), dietary myristic acid, and milk production. Milk fat proportion was best predicted by dietary unsaturated FA, NDF, and forage. De novo FA in milk was predicted by dry matter intake (DMI) and dietary FA, while preformed FA was predicted by DMI, dietary oleic and linoleic acids. In conclusion, this study emphasizes the importance of the dietary FA profile in evaluating the effects of lipids on milk fat production and FA profile. Accurate and precise predictions of milk fat production, proportion, and FA profile can be achieved by considering cow production and dietary characteristics.

Effects of replacement of barley with oats on milk fatty acid composition in dairy cows fed grass silage-based diets

This study consists of milk fatty acid (FA) data collected during 2 in vivo experiments. For this study, 8 cows from each experiment were included in a replicated 4 × 4 Latin square design. At the start of experiment 1 (Exp1) cows were at (mean ± standard deviation) 87 ± 34.6 d in milk, 625 ± 85.0 kg of body weight, and 32.1 ± 4.17 kg/d milk yield and at the start of experiment 2 (Exp2) cows were at 74 ± 18.2 d in milk, 629 ± 87.0 kg of body weight, and 37.0 ± 3.2 kg/d milk yield. In Exp1, we examined the effects of gradual replacement of barley with hulled oats (oats with hulls) on milk FA composition. The basal diet was grass silage and rapeseed meal (58 and 10% of diet DM, respectively), and the 4 grain supplements were formulated so that barley was gradually replaced by hulled oats at levels of 0, 33, 67, and 100% on dry matter basis. In Exp2, we examined (1) the effects of replacing barley with both hulled and dehulled oats (oats without hulls) and (2) the effects of gradual replacement of hulled oats with dehulled oats on milk FA composition. The basal diet was grass silage and rapeseed meal (60 and 10% of diet DM, respectively), and the 4 pelleted experimental concentrates were barley, hulled oats, a 50:50 mixture of hulled and dehulled oats, and dehulled oats on dry matter basis. In Exp1, gradual replacement of barley with hulled oats decreased relative proportions of 14:0, 16:0, and total saturated FA (SFA) in milk fat linearly, whereas proportions of 18:0, 18:1, total monounsaturated FA, and total cis unsaturated FA increased linearly. Transfer efficiency of total C18 decreased linearly when barley was replaced by hulled oats in Exp1. In Exp2, relative proportions of 14:0, 16:0, and total SFA were lower, whereas proportions of 18:0, 18:1, monounsaturated FA, and cis unsaturated FA were higher in milk from cows fed the oat diets than in milk from cows fed the barley diet. Moreover, in Exp2, gradual replacement of hulled oats with dehulled oats slightly decreased the relative proportion of 14:0 in milk fat but did not affect the proportions of 16:0, 18:0, 18:1, total SFA, monounsaturated FA, trans FA, or polyunsaturated FA. In Exp2, transfer efficiency of total C18 was lower when cows were fed the oat diets than when fed the barley diet and decreased linearly when hulled oats were replaced with dehulled oats. Predictions of daily CH4 emissions (g/d) using the on-farm available variables energy-corrected milk yield and body weight were not markedly improved by including milk concentrations of individual milk FA in prediction equations. In conclusion, replacement of barley with oats as a concentrate supplement for dairy cows fed a grass silage-based diet could offer a practical strategy to change the FA composition of milk to be more in accordance with international dietary guidelines regarding consumption of SFA.

Effects of Heavy Metal Exposure from Leather Processing Plants on Serum Oxidative Stress and the Milk Fatty Acid Composition of Dairy Cows: A Preliminary Study.

Simple SummaryThe leather industry has raised the blood lead and arsenic levels of cows in nearby farms. Significant decreases in serum GST, GPX, and GSH activity were observed in the polluted area. Milk linoleic acid (C18:2n6c) was significantly reduced in the polluted area. Heavy metal exposure through leather industry imposes oxidative stress on cows, leading to modifications in the unsaturated fatty acids of milk.This study investigated whether unsaturated fatty acids in milk and the oxidative status of cows are affected by heavy metal exposure due to leather processing. The blood lead (Pb) concentrations in cows from two farms in the polluted area were 16.27 ± 8.63 μg/L, respectively, which were significantly (p < 0.05) higher than the blood Pb concentrations in cows from an unpolluted farm (6.25 ± 3.04 μg/L). There were significantly (p < 0.05) lower levels of glutathione S-transferase (GST), glutathione peroxidase (GPX), and glutathione (GSH) in the serum of cows from the polluted area compared to the levels in cows from an unpolluted area. The linoleic acid (C18:2n6c) content in milk from the polluted area was 15% lower than in the control area. There was a significant correlation between linoleic acid in milk with the blood Pb and serum GSH levels. Heavy metals can alter fatty acid synthesis through oxidative stress, which may be the mechanism by which heavy metals affect fatty acid synthesis in milk.

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 SummaryCows 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. 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.

Effects of dietary microalgae (Schizochytrium spp.) supplement on milk performance, blood parameters, and milk fatty acid composition in dairy cows

The objective of this study was to examine the effects of dietary inclusion of microalgae (Schizochytrium spp.) on milk yield, milk composition, and docosahexaenoic acid (DHA) transfer efficiency in dairy cows. Thirty-six lactating Chinese-Holstein dairy cows were randomly allocated to three treatment groups (n = 12; 0, 170, and 255 g microalgae supplement per day) in a 60-day experimental period. No significant treatment effect was observed on DMI and milk performance. Similarly, there was no significant microalgae supplement effect on blood haematological and biochemical parameters, except for platelets (P &amp;lt; 0.01) and thrombocytosis (P &amp;lt; 0.01), suggesting that the inclusion of microalgae in dairy cow diets would not affect production performance and animal health. Compared to the control group, adding 170 and 255 g microalgae to diets significantly increased the proportion of linoleic acid, DHA, n-3 and n-3/n-6 ratio in the blood (P &amp;lt; 0.05). Consequently, DHA concentration and n-3/n-6 ratio were increased in milk, indicating that the milk fatty acid composition could be affected by nutritional manipulation. The overall DHA transfer efficiency was 10.1% and 11.3% for 170 and 255 g microalgae supplement, suggesting that the addition of microalgae to dairy cow diets is a feasible strategy to produce DHA enriched milk in practice.

Feeding oregano oil and its main component carvacrol does not affect ruminal fermentation, nutrient utilization, methane emissions, milk production, or milk fatty acid composition of dairy cows

Because of their antimicrobial properties, essential oils and their components have been suggested as alternatives to other antimicrobials (e.g., monensin) that are commonly fed to ruminants to improve nutrient utilization and enhance feed efficiency and milk performance. In this study, we evaluated the potential of oregano oil and its main component (carvacrol) as rumen modifiers. For this purpose, 8 ruminally cannulated lactating dairy cows (92 ± 11 d in milk, 36.5 ± 7.6 kg of milk yield, and 703 ± 74 kg of body weight) were used in a double 4 × 4 Latin square (28-d periods). Cows were fed 1 of the 4 following treatments: (1) control (CTL, no additive); (2) monensin [MON, 24 mg/kg of dry matter (DM)]; (3) oregano oil (ORE, 50 mg/kg of DM); and (4) carvacrol (CAR, 50 mg/kg of DM). Cows were fed (ad libitum intake) a total mixed ration consisting of 60% forages (corn silage and alfalfa silage) and 40% concentrates, on a DM basis. Feeding ORE and CAR had no effect on nutrient total-tract apparent digestibility, N utilization, rumen fermentation (i.e., pH, ammonia, volatile fatty acids), protozoa counts, or milk performance. Feeding MON increased the molar proportion of propionate and tended to increase total-tract apparent digestibility of crude protein. None of the feed additives evaluated affected enteric methane production (491 g/d, 21.1 g/kg of DM intake, 6.14% of gross energy intake on average). Milk fatty acid composition was not changed by ORE or CAR, but MON increased the proportion of trans-10 18:1, an intermediate of ruminal biohydrogenation. Thus, when included at 50 mg/kg of dietary dry matter, neither oregano oil nor carvacrol favorably altered rumen fermentation, improved nutrient utilization or milk performance, or mitigated enteric methane emissions in dairy cows.

Effect of dried oregano (Origanum vulgare L.) plant material in feed on methane production, rumen fermentation, nutrient digestibility, and milk fatty acid composition in dairy cows

Essential oils (EO) from oregano may have antimicrobial properties, potentially representing a methane mitigation strategy suitable for organic production. This study aimed to (1) examine the potential of oregano in lowering enteric methane production of dairy cows fed differing levels of dried oregano (Origanum vulgare ssp. hirtum) plant material containing high levels of EO; (2) determine whether differing levels of dried oregano plant material of another subspecies (Origanum vulgare ssp. vulgare) with naturally low levels of EO in feed affected enteric methane production; and (3) evaluate the effect of various levels of the 2 oregano subspecies (containing high or low levels of EO) in feed on rumen fermentation, nutrient digestibility, and milk fatty acids. Each experiment had a 4 × 4 Latin square design using 4 lactating Danish Holstein dairy cows that had rumen, duodenal, and ileal cannulas and were fed 4 different levels of oregano. Experiment 1 used low EO oregano [0.12% EO of oregano dry matter (DM)] and evaluated a control (C) diet with no oregano and 3 oregano diets with 18 (low; L), 36 (medium; M), and 53 g of oregano DM/kg of dietary DM (high; H). Experiment 2 used high EO oregano (4.21% EO of oregano DM) with 0, 7, 14, and 21 g of oregano DM/kg of dietary DM for C, L, M, and H, respectively. Oregano was added to the diets by substituting grass/clover silage on a DM basis. Low or high EO oregano in feed did not affect dry matter intake (DMI) or methane production (grams per day, grams per kilogram of DMI, grams per kilogram of energy-corrected milk, and percentage of gross energy intake). Rumen fermentation was slightly affected by diet in experiment 1, but was not affected by diet in experiment 2. In both experiments, the apparent total-tract digestibility of DM, organic matter, and neutral detergent fiber decreased linearly and cubically (a cubic response was not observed for neutral detergent fiber) with increasing dietary oregano content, while milk fatty acids were slightly affected. In conclusion, dried oregano plant material with either high or low levels of EO did not lower the methane production of dairy cows over 4 consecutive days, and no substantial effects were observed on rumen fermentation or nutrient digestibility. This conclusion regarding methane production is in contrast with literature and requires further study.

The effect of oak tannin (Quercus robur) and hops (Humulus lupulus) on dietary nitrogen efficiency, methane emission, and milk fatty acid composition of dairy cows fed a low-protein diet including linseed

The objective of this study was to test the effects of inclusion of hop pellets (HP) and oak tannin extracts (OT) alone or in combination on N efficiency, methane (CH4) emission, and milk production and composition in 2 experiments with dairy cows fed low-N rations supplemented with linseed. In both experiments, 6 lactating Holstein cows were assigned to 3 dietary treatments in a 3 × 3 duplicated Latin square design (21-d periods). Cows were fed a total mixed ration at a restricted level to meet their nutrient requirements. In experiment 1, 169 g dry matter (DM) of OT or 56 g DM of HP was included separately in the control diet (C1). In experiment 2, the additives were included together (OT-HP) in the control diet (C2) similar to C1. Diet C2 was compared with a control without linseed (C0). In experiment 1, the supplementation of the control diet with OT decreased urinary N excretion by 12%. In experiment 2, the combination of OT and HP decreased urinary N by 7%. Oak tannin extracts and HP alone or in combination did not influence the daily enteric CH4 production of cows. Cows fed diet C0 produced 17% more enteric CH4 daily than those fed diet C2. Intake of diet C2, which contained 6.7% extruded linseed on a DM basis (experiment 2), decreased the sum of 6:0 to 14:0 fatty acids (-16%) and palmitic acid (-26%) and increased the stearic acid (+50%), oleic acid (+36%), vaccenic acid (trans-11 18:1; +285%), rumenic acid (cis-9,trans-11 18:2; +235%), and α-linolenic acid (+100%) in milk fat. The supplementation of diet C2 with the OT-HP mixture further improved the milk's fatty acid composition. Intake of the OT alone increased α-linolenic acid by 17.7% (experiment 1). The results of this study show that at the economically acceptable dose we tested, hops had no effect on urinary N excretion, CH4 emission, milk production, and milk composition. By contrast, supplementation of diets with oak tannin extract can be considered for reducing urinary N excretion. The combination of oak tannin and hops had no more effect than oak tannin alone except on the milk fatty acid profile, which was favorably influenced from a nutritional point of view.

Effect of Conjugated Linoleic Acid Supplement and Sesame as Source of N-6 on Performance and Milk Fatty Acid Profile of Holstein Dairy Cows During Transition Period

Background: Feeding unsaturated fatty acids sources in dairy cows is considered as a strategy to improve animal health during postpartum period and milk fatty acid profile. OBJECTIVES: This study aimed to investigate the effects of conjugated linoleic acid supplement and combination of sesame meal and oil on performance and milk fatty acid composition of dairy cows during transition period. METHODS: Twenty-one multiparous Holstein cows (249 days of pregnancy) were randomly assigned to 3 dietary treatments including: 1) control with a source of calcium salts of palm oil (0.95 and 1.68% of the dry matter in prepartum and postpartum diets, respectively), 2) conjugated linoleic acid supplementation (0.4 and 0.5% of the dry matter in prepartum and postpartum diets, respectively) 3) sesame meal (2.18 and 4.32% of the dry matter in prepartum and postpartum diets, respectively) and calcium salt of sesame oil (0.83 and 1.4% of the dry matter in prepartum and postpartum diets, respectively) as source of n-6. RESULTS: Dry matter intake, body weight, body condition score, average milk yield and component including fat, protein and lactose were not affected by dietary treatments. The proportion of short and medium chain fatty acids, monounsaturated fatty acids and polyunsaturated fatty acids were not affected by dietary treatments. Conjugated linoleic acid supplement numerically increased content of cis-9, trans-11 conjugated linoleic acid and reduced short chain fatty acids ( CONCLUSIONS: Feeding conjugated linoleic acid supplement and combination of sesame meal and oil had no effect on performance, milk composition and fatty acid profile.

Effects of seasonal variation and winter supplementation of ground whole flaxseed on milk fatty acid composition of dairy cows in organic farms in the northeastern United States

<h2>ABSTRACT</h2> Fourteen organic dairy farms in the northeastern United States were used to evaluate (1) seasonal variation in bioactive milk fatty acid (FA) profile from 2012 to 2015 and (2) supplementation of ground whole flaxseed (GFLX) to maintain elevated concentrations of bioactive milk FA during the nongrazing season. During regular farm visits, milk, feed, and pasture samples were collected, and diet composition, milk yield, and milk composition were recorded. During winters of 2013 to 2014 and 2014 to 2015, 9 farms supplemented GFLX at 6% of diet DM to half of each herd (n = 238 cows per treatment). Milk samples were collected and pooled by treatment (GFLX or control). Data were analyzed using the MIXED procedure of SAS. A significant month × year interaction (<i>P</i> < 0.05) for n-3 FA showed an increase beginning in April of 2014 through the end of the study. The proportion of conjugated linoleic acid showed a seasonal pattern with greatest (<i>P</i> < 0.05) concentrations (1.32% of total milk FA) during the grazing season. Winter GFLX supplementation did not affect (<i>P</i> > 0.15) milk yield or concentrations of milk fat or protein; however, BCS tended (<i>P</i> = 0.08) to be greater for GFLX cows. Compared with the control diet, GFLX decreased (<i>P</i> < 0.05) total milk SFA by 3.1 percentage units and increased (<i>P</i> < 0.05) n-3 by 62% and total conjugated linoleic acid proportion by 9%. Although GFLX supplementation increased milk n-3, lesser effects on SFA and total conjugated linoleic acid proportions indicated that a greater level of winter supplementation is required to improve overall milk FA profile during the nongrazing season.

Effects of carbohydrate type or bicarbonate addition to grass silage-based diets on enteric methane emissions and milk fatty acid composition in dairy cows

The aim of the study was to compare the effect of fiber- or starch-rich diets based on grass silage, supplemented or not with bicarbonate, on CH4 emissions and milk fatty acid (FA) profile in dairy cows. The experiment was conducted as a 4 × 4 Latin square design with a 2 × 2 factorial arrangement: carbohydrate type [starch- or fiber-rich diets with dietary starch level of 23.1 and 5.9% on a dry matter basis, respectively], without or with bicarbonate addition [0 and 1% of the dry matter intake, respectively]. Four multiparous lactating Holstein cows were fed 4 diets with 42% grass silage, 8% hay, and 50% concentrate in 4 consecutive 4-wk periods: (1) starch-rich diet, (2) starch-rich diet with bicarbonate, (3) fiber-rich diet, and (4) fiber-rich diet with bicarbonate. Intake and milk production were measured daily and milk composition was measured weekly; CH4 emission and total-tract digestibility were measured simultaneously (5 d, wk 4) when animals were in open-circuit respiration chambers. Sensors continuously monitored rumen pH (3 d, wk 4), and fermentation parameters were analyzed from rumen fluid samples taken before feeding (1 d, wk 3). Cows fed starch-rich diets had less CH4 emissions (on average, -18% in g/d; -15% in g/kg of dry matter intake; -19% in g/kg of milk) compared with fiber-rich diets. Carbohydrate type did not affect digestion of nutrients, except starch, which increased with starch-rich diets. The decrease in rumen protozoa number (-36%) and the shift in rumen fermentation toward propionate at the expense of butyrate for cows fed the starch-rich diets may be the main factor in reducing CH4 emissions. Milk of cows fed starch-rich diets had lower concentrations in trans-11 C18:1, sum of cis-C18, cis-9,trans-11 conjugated linoleic acid (CLA), and sum of CLA, along with greater concentration of some minor isomers of CLA and saturated FA in comparison to the fiber-rich diet. Bicarbonate addition did not influence CH4 emissions or nutrient digestibility regardless of the carbohydrate type in the diet. Rumen pH increased with bicarbonate addition, whereas other rumen parameters and milk FA composition were almost comparable between diets. Feeding dairy cows a starch-rich diet based on grass silage helps to limit the negative environmental effect of ruminants, but does not lead to greater milk nutritional value because milk saturated FA content is increased.

Plant oil supplements reduce methane emissions and improve milk fatty acid composition in dairy cows fed grass silage-based diets without affecting milk yield

Four lipid supplements varying in chain length or degree of unsaturation were examined for their effects on milk yield and composition, ruminal CH4 emissions, rumen fermentation, nutrient utilization, and microbial ecology in lactating dairy cows. Five Nordic Red cows fitted with rumen cannulas were used in a 5 × 5 Latin square with five 28-d periods. Treatments comprised total mixed rations based on grass silage with a forage-to-concentrate ratio of 60:40 supplemented with no lipid (CO) or 50 g/kg of diet dry matter (DM) of myristic acid (MA), rapeseed oil (RO), safflower oil (SO), or linseed oil (LO). Feeding MA resulted in the lowest DM intake, and feeding RO reduced DM intake compared with CO. Feeding MA reduced the yields of milk, milk constituents, and energy-corrected milk. Plant oils did not influence yields of milk and milk constituents, but reduced milk protein content compared with CO. Treatments had no effect on rumen fermentation characteristics, other than an increase in ammonia-N concentration due to feeding MA, RO, and SO compared with CO. Lipid supplements reduced daily ruminal CH4 emission; however, the response was to some extent a result of lower feed intake. Lipids modified microbial community structure without affecting total counts of bacteria, archaea, and ciliate protozoa. Dietary treatments had no effect on the apparent total tract digestibility of organic matter, fiber, and gross energy. Treatments did not affect either energy secreted in milk as a proportion of energy intake or efficiency of dietary N utilization. All lipids lowered de novo fatty acid synthesis in the mammary gland. Plant oils increased proportions of milk fat 18:0, cis 18:1, trans and monounsaturated fatty acids, and decreased saturated fatty acids compared with CO and MA. Both SO and LO increased the proportion of total polyunsaturated fatty acids, total conjugated linolenic acid, and cis-9,trans-11 conjugated linoleic acid. Feeding MA clearly increased the Δ9 desaturation of fatty acids. Our results provide compelling evidence that plant oils supplemented to a grass silage-based diet reduce ruminal CH4 emission and milk saturated fatty acids, and increase the proportion of unsaturated fatty acids and total conjugated linoleic acid while not interfering with digestibility, rumen fermentation, rumen microbial quantities, or milk production.

1330 Effects of feeding different forms of polyunsaturated fatty acids on performance, plasma metabolites and milk fatty acid composition of dairy cows

1330 Effects of feeding different forms of polyunsaturated fatty acids on performance, plasma metabolites and milk fatty acid composition of dairy cows

0758 Effects of feeding different forms of polyunsaturated fatty acids on performance, plasma metabolites, and milk fatty acid composition of dairy cows

0758 Effects of feeding different forms of polyunsaturated fatty acids on performance, plasma metabolites, and milk fatty acid composition of dairy cows

The effect of “Remivital” on plasma amino acid composition in dairy cows with ketosis

Aim. To investigate plasma amino acid composition in dairy cows after ketosis conventional (oral administra- tion of propylene glycol, intravenous injection of glucose and insulin) and proposed treatment (oral administra- tion of propylene glycol, intravenous injection of “Remivital”). Methods. Study was performed on high yield- ing dairy cows with clinical ketosis during their 2 nd to 4 th lactation with milk yield above 8000 L per previous lactation. Content of free amino acids was determined in plasma before and after treatment using amino acid analyzer. Results. Lowering of the level of ketogenic amino acids was revealed after conducted treatment as well as increase in the level of glycogenic and branched amino acids. Signifi cant lowering of the level of meth- ylhistidine gives evidence of decreased catabolism of contractile proteins. Conclusions. Proposed treatment regimen has proven to be superior, since signifi cantly higher level of ornithine and lower level of citrulline were revealed after administration of conventional regimen, which gives evidence of problems in disposal of ammonia and lactate. Moreover, in case of administration of traditional scheme, the concentration of markers of catabolism of contractile proteins was still high, in contrast with such in animals, which were administered proposed regimen, and high concentration of isoleucine contributes to aggravation of ketoacidosis.

Effects of candidate gene polymorphisms on the detailed fatty acids profile determined by gas chromatography in bovine milk

Association analyses between candidate genes and bovine milk fatty acids can improve our understanding of genetic variation in milk fatty acid profiles and reveal potential opportunities to tailor milk fat composition through selection strategies. In this work, we investigated the association of 51 single nucleotide polymorphisms (SNP) selected from 37 candidate genes using a functional and positional approach, with 47 fatty acids, 9 fatty acid groups, and 5 Δ9-desaturation indices in milk samples from Brown Swiss cows. Individual milk samples were collected from 1,158 Italian Brown Swiss cows, and gas chromatography was used to obtain detailed milk fatty acid compositions. A GoldenGate assay system (Illumina, San Diego, CA) was used to perform genotype 96 selected SNP located in 54 genes across 22 chromosomes. In total, 51 polymorphic SNP in 37 candidate genes were retained for the association analysis. A Bayesian linear animal model was used to estimate the contribution of each SNP. A total of 129 tests indicated relevant additive effects between a given SNP and a single fatty acid trait; 38 SNP belonging to 30 genes were relevant for a total of 57 fatty acid traits. Most of the studied fatty acid traits (~81%) were relevantly associated with multiple SNP. Relevantly associated SNP were mainly found in genes related to fat metabolism, linked to or contained in previously identified quantitative trait loci for fat yield or content, or associated with genes previously identified in association analyses with milk fatty acid profiles in other cow breeds. The most representative candidate genes were LEP, PRL, STAT5A, CCL3, ACACA, GHR, ADRB2, LPIN1, STAT1, FABP4, and CSN2. In particular, relevant associations with SNP located on bovine chromosome 19 (BTA19) were found. Two candidate genes on BTA19 (CCL3 and ACACA) were relevantly associated with de novo short- and medium-chain fatty acids, likely explaining the high heritability values found for these fatty acids (with the exception of C6:0). Two additional genes on BTA19 (CCL2 and GH1) showed associations with saturated and branched-chain fatty acids. Our findings provide basic information on genes and SNP affecting the milk fatty acid composition of dairy cows. These results may support the possibility of using genetic selection to modify milk fatty acid profiles to promote beneficial health-related effects.

Effect of linseed oil supplementation on performance and milk fatty acid composition in dairy cows.

Thirty-six Holstein-Friesian crossbred lactating dairy cows were used to determine the effects of linseed oil supplementation on performance and milk fatty acid (FA) profile. Three treatments were as follows: basal diet (56:44 Roughage:concentrate [R:C] ratio, dry matter basis) supplemented with 500 g of palm oil as control (PO), 500 g mixture (1:1, w/w) of palm oil and linseed oil (POLSO) and 500 g of linseed oil (LSO). The LSO supplementation had no effects on total dry matter intake (DMI), milk yield and milk composition. Compared to control cows, cows supplemented with LSO increased milk concentrations of cis-9,trans-11 conjugated linoleic acid (CLA) and n-3 FA (P < 0.05), particularly C18:3n-3, C20:5n-3 and C22:6n-3. Feeding LSO reduced concentrations of milk short- and medium-chain saturated fatty acids (P < 0.05) while it increased concentration of milk unsaturated fatty acids (P < 0.05). Milk proportions of n-3 FA increased, whereas n-6/n-3 ratio decreased in the LSO as compared with the control (P < 0.05). In conclusion, supplementing dairy cows' diet based on corn silage with LSO at 500 g/day could improve the nutritional value of milk with potential health-beneficial FA without detrimental effect on milk composition or cow's performance.

Effects of Feeding Garlic and Juniper Berry Essential Oils on Milk Fatty Acid Composition of Dairy Cows.

Essential oils (EOs) from plant extracts have been reported to have an antibacterial activity against gram-negative and gram-positive bacteria. Several of the gram-positive bacteria are involved in ruminal biohydrogenation of fatty acids (FAs), thus suggesting that feeding EOs could lower biohydrogenation of FA because of a decrease in the number of bacteria involved in that process. As a result, milk FA profiles are expected to be modified. In addition, monensin was approved as an antibiotic to be fed in dairy cattle, and it was reported that dairy cows supplemented with monensin produced milk containing higher concentration of 18:1 t10 and 18:1 t11. The objective of this study was to evaluate the effects of two EOs (garlic and juniper berry oils) and monensin on FA profiles of milk fat. Four ruminally fistulated Holstein dairy cows were used in a 4 × 4 Latin square experiment. Cows were fed for ad libitum intake a total mixed ration without supplementation (control), or supplemented with monensin (330 mg/head per day), garlic oil (5 g/head per day), or juniper berry oil (2 g/head per day). The FA composition of saturated, monounsaturated, or polyunsaturated was not affected by supplementation of EO and monensin. However, proportion of conjugated linoleic acid trans 10, cis 12 (CLA t10, c12) was higher (P < 0.05) for cows fed EO or monensin than for control cows. Supplementation of monensin increased (P < 0.05) the proportion of total trans FA compared with the control. These results indicate that supplementation of the dairy cow diet with garlic or juniper berry EO or monensin had the potential to increase the proportion of CLA t10, c12 in milk fat with minimal overall effects on FA of milk fat. The results also confirm the increase of 18:1 t10 in milk fat by feeding monensin to dairy cows.

Milk fatty acid composition of dairy cows fed green whole-plant buckwheat, phacelia or chicory in their vegetative and reproductive stage

The hypothesis was tested that the phenological stage of dicotyledonous forages influences milk fatty acid (FA) composition of dairy cows. For this purpose buckwheat (Fagopyrum esculentum) and phacelia (Phacelia tanacetifolia; both in their first year of cultivation) as well as chicory (Cychorium intybus; second year) were cultivated in mixture with ryegrass (Lolium multiflorum). After 35 days of growth, feeding the green forages to 3×6 late lactating dairy cows at ad libitum access started. The realized dietary dry matter proportions of the test plants were (vegetative and reproductive stage): buckwheat, 0.60 and 0.55; chicory, 0.70 and 0.69; phacelia, 0.51 and 0.48. Experimental feeding lasted for 23, 17 and 26 days with buckwheat, chicory and phacelia, respectively. The complete diets additionally contained 2kg of concentrate and 1kg of barley straw per day per animal. Milk and feed samples were analyzed from every second day. Feedstuffs were analyzed for proximate contents, FA and fractions of phenolic compounds. In milk samples solids and FA were measured. Contents of FA and of phenol fractions decreased during advancing development stage in all test plants except total extractable phenols and total tannins in phacelia. This decrease was particularly pronounced for α-linolenic acid (ALA) and linoleic acid (LA) in buckwheat. Phenological stage had no influence on milk yield and gross composition, but ALA and LA proportions of milk fat declined with time in all groups. Proportions of ALA (14.2g/kg FA) and total poly-unsaturated FA in milk fat were highest with phacelia. Levels of conjugated linoleic acid (CLA) in milk fat were not affected by treatment or phenological stage. Vaccenic acid in milk fat was slightly elevated when feeding buckwheat and phacelia in the reproductive stage whereas it decreased with ongoing development in the chicory group. No systematic influence of phenological stage on the relative recovery of feed FA in milk fat occurred. The study did not confirm the hypothesis that the recovery rate of ALA would increase with maturing of the forages. In terms of generating a desired milk FA profile, phacelia and chicory seem however to be generally promising.

Nitrogen balance, blood metabolites and milk fatty acid composition of dairy cows fed pomegranate-peel extract

An experiment was carried out to determine the effect of pomegranate peel extract (PPE) on nitrogen balance, blood parameters and the milk fatty acid profile of dairy cows. Four Holstein cows were used in a 4×4 Latin square design with 28-d periods and 4 treatments: PPE0 (no extract), PPE400 (400ml PPE/cow/d), PPE800 (800ml PPE/cow/d) and PPE1200 (1200ml PE/cow/d). Nitrogen balance, blood parameters and the milk fatty acid profile were measured. Determination of secondary metabolites showed its high content of aqueous fraction, total phenolics and total tannin with reasonable content of saponins. Outputs of N in milk were quadratically increased (P=0.044) by inclusion of PPE at 400 and 800ml PPE/cow/d in the diet. Blood cholesterol (quadratic effect, P=0.043), blood urea nitrogen (linear effect, P=0.047) and milk urea nitrogen (quadratic effect, P=0.0008) concentrations decreased with adding PPE. Supplementation with PPE quadratically lowered total saturated fatty acid (P=0.005), proportions of C12:0 (linear effect=0.040), C16:1c9 (quadratic effect, P=0.011), C18:0 (linear effect, P=0.083, quadratic effect, P=0.011) and ω6/ω3 (quadratic effect, P=0.007). Amount of C18:3c (n-3) (linear effect, P=0.046), DHA (C22:6) (quadratic effect, P=0.009) and EPA (C20:5) (quadratic effect, P=0.012) were increased by inclusion of PPE. Adding PPE lowered blood cholesterol, blood urea nitrogen and milk urea nitrogen. Milk from cows fed PE had significantly lower total saturated fatty acid, desirable ω6/ω3 ratio and higher content of EPA and DHA.