Effect of intake of pasture on concentrations of conjugated linoleic acid in milk of lactating cows

Impact of varying levels of pasture allowance on the nutritional quality and functionality of milk throughout lactation

The objective of this study was to examine the impact of increasing proportions of grazed pasture in the diet on the composition, quality, and functionality of bovine milk across a full lactation. Fifty-four spring-calving cows were randomly assigned to 1 of 3 groups (n = 18), blocked on the basis of mean calving date (February 15, 2020 ± 0.8 d), pre-experimental daily milk yield (24.70 ± 3.70 kg), milk solids yield (2.30 ± 0.27 kg), lactation number (3.10 ± 0.13), and economic breeding index (182 ± 19). Raw milk samples were obtained weekly from each group between March and November 2020. Group 1 (GRS) consumed perennial ryegrass and was supplemented with 5% concentrates (dry matter basis); group 2 was maintained indoors and consumed a total mixed ration (TMR) diet consisting of maize silage, grass silage, and concentrates; and group 3 consumed a partial mixed ration diet (PMR), rotating between perennial ryegrass during the day and indoor TMR feeding at night. Raw milk samples consisted of a pooled morning and evening milking and were analyzed for gross composition, free amino acids, fatty acid composition, heat coagulation time, color, fat globule size, and pH. The TMR milks had a significantly higher total solids, lactose, protein, and whey protein as a proportion of protein content compared with both GRS and PMR milks. The GRS milks demonstrated a significantly lower somatic cell count (SCC), but a significantly higher pH and b*-value than both TMR and PMR milks. The PMR milks exhibited significantly lower total solids and fat content, but also demonstrated significantly higher SCC and total free amino acid content compared with GRS and TMR. Partial least squares discriminant analysis of fatty acid profiles displayed a distinct separation between GRS and TMR samples, while PMR displayed an overlap between both GRS and TMR groupings. Variable importance in projection analysis identified conjugated linoleic acid cis-9,trans-11, C18:2n-6 cis, C18:3n-3, C11:0, and C18:2n-6 trans as the largest contributors to the variation between the diets. Milk fats derived from GRS diets exhibited the highest proportion of unsaturated fats and higher unsaturation, health-promoting, and desaturase indices. The lowest proportions of saturated fats and the lowest atherogenic index were also exhibited by GRS-derived milk fats. This work highlights the positive influence of grass-fed milk for human consumption through its more nutritionally beneficial fatty acid profile, despite the highest milk solid percentages derived from TMR feeding systems. Furthermore, this study demonstrates the proportional response of previously highlighted biomarkers of pasture feeding to the proportion of pasture in the cow's diet.

Trend analysis and prediction of seasonal changes in milk composition from a pasture-based dairy research herd

The composition of seasonal pasture-produced milk is influenced by stage of lactation, animal genetics, and nutrition, which affects milk nutritional profile and processing characteristics. The objective was to study the effect of lactation stage (early, mid, and late lactation) and diet on milk composition in an Irish spring calving dairy research herd from 2012 to 2020 using principal component and predictive analytics. Crude protein, casein, fat, and solids increased from 2012 to 2020, whereas lactose concentration peaked in 2017, then decreased. Based on seasonal data from 2013 to 2016, forecasting models were successfully created to predict milk composition for 2017 to 2020. The diet of cows in this study is dependent upon grass growth rates across the milk production season, which in turn, are influenced by weather patterns, whereby extreme weather conditions (rainfall and temperature) were correlated with decreasing grass growth and increasing nonprotein nitrogen levels in milk. The study demonstrates a significant change in milk composition since 2012 and highlights the effect that seasonal changes such as weather and grass growth have on milk composition of pasture-based systems. The potential to forecast milk composition at different stages of lactation benefits processers by facilitating the optimization of in-process and supply logistics of dairy products.

Improved biological value of eggs due to the addition of pomegranate seed oil to laying-hen diets

In this study, the effects of the addition of pomegranate seed oil (PSO) at different levels (0, 0.5, 1, and 1.5  mL kg - 1 ) to laying-hen rations on performance values, egg quality criteria, egg shelf life, some enzyme activity, and the fatty acid composition of yolks were investigated. In the study, 96 Lohman LSL laying hens at 64 weeks of age were used. The trial consisted of four groups, each containing 24 hens. Chickens were given feed and water ad libitum during the 8-week experiment. The first group was the control group and was fed with a basal diet, while the other groups were fed with feeds with 0.5, 1.0, and 1.5  mL kg - 1 PSO added to the basal feed, respectively. The lowest feed consumption and the highest egg weight were determined in the 1  mL kg - 1 PSO group. The highest feed conversion ratio, the lowest eggshell weight, and the shell-breaking strength were determined in the 0.5  mL kg - 1 PSO group. It was determined that the egg yolk malondialdehyde (MDA) value in the groups to which pomegranate seed oil was added was significantly lower than the control group on the 28th day of storage. The lowest glutation (GSH) and catalase values were found in the control group, and the highest total antioxidant capacity (TAC) was found in the 1  mL kg - 1 PSO group. It was determined that the addition of PSO to the diet significantly increased the rate of saturated fatty acids (SEFA), conjugated linoleic acid (CLA), and conjugated linolenic acids (CLnA) in yolk. The results showed that the addition of 1  mL kg - 1 pomegranate seed oil to the feeds decreased feed consumption, increased egg weight, and positively affected the shelf life of the egg. In short, the addition of PSO had a positive effect on shelf life, and it increased punicic acid and CLA levels without reducing egg quality.

Prediction of Indirect Indicators of a Grass-Based Diet by Milk Fourier Transform Mid-Infrared Spectroscopy to Assess the Feeding Typologies of Dairy Farms

This research aims to develop a predictive model to discriminate milk produced from a cattle diet either based on grass or not using milk mid-infrared spectrometry and the month of testing (an indirect indicator of the feeding ration). The dataset contained 3,377,715 spectra collected between 2011 and 2021 from 2449 farms and 3 grazing traits defined following the month of testing. Records from 30% of the randomly selected farms were kept in the calibration set, and the remaining records were used to validate the models. Around 90% of the records were correctly discriminated. This accuracy is very good, as some records could be erroneously assigned. The probability of belonging to the GRASS modality allowed confirmation of the model's ability to detect the transition period even if the model was not trained on this data. Indeed, the probability increased from the spring to the summer and then decreased. The discrimination was mainly explained by the changes in the milk fat, mineral, and protein compositions. A hierarchical clustering from the averaged probability per farm and year highlighted 12 groups illustrating different management practices. The probability of belonging to the GRASS class could be used in a tool counting the number of grazing days.

Fatty acid profile characterization in colostrum, transition milk, and mature milk of primi- and multiparous cows during the first week of lactation

The specific fatty acid (FA) profile of colostrum may indicate a biological requirement for neonatal calves. The objective of this study was to characterize the FA profile and yields in colostrum, transition milk, and mature milk in primiparous (PP) and multiparous (MP) cows. Colostrum was milked from 10 PP and 10 MP Holstein cows fed the same pre- and postpartum rations. Milkings (M) 2 to 5 and 12 were respectively termed transition and mature milk. Overall, short-chain FA (C4:0 and C6:0) were 61 and 50% lower in colostrum than mature milk, respectively. A parity by milking interaction was also present, with higher C4:0 for PP cows at M2 and for MP cows at M12. Additionally, higher concentrations of C6:0 were present for PP cows at M2 through M4 and for MP cows at M12. Palmitic (C16:0) and myristic (C14:0) acids were 38% and 19% higher in colostrum than mature milk, respectively. However, total saturated FA remained relatively stable. Branched-chain FA were 13% lower in colostrum than mature milk and higher in PP than MP cows throughout the milking period. The proportion of trans-monounsaturated FA (MUFA) was 72% higher in PP cows throughout the milking period, as well as 13% lower in colostrum than mature milk. In contrast, cis-MUFA and total MUFA were not affected by milking nor parity. Linoleic acid (LA) was 25% higher in colostrum than transition and mature milks, but α-linolenic acid (ALA) did not differ. Consequently, the ratio of LA to ALA was 29% higher in colostrum than mature milk and 33% higher in MP cows. Linoleic acid was also 15% higher in MP cows, whereas ALA was 15% higher in PP cows. Conjugated linoleic acid (CLA, cis-9,trans-11) was 2.7-fold higher in PP cows, and no differences between colostrum and mature milk were detected. Overall, polyunsaturated FA (PUFA) from the n-6 and n-3 series were over 40% higher in colostrum compared with transition and mature milk. Milking by parity interactions were present for arachidonic acid (ARA), eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), docosahexaenoic acid (DHA), and total n-3 PUFA, translating to higher proportions in PP cows in M1 to M3, whereas proportions remained relatively stable throughout the milking period in MP cows. Despite increasing milk yields throughout the subsequent milkings, higher yields of EPA, ARA, DPA, and DHA were present in colostrum than in mature milk. Greater proportions and yields of n-3 and n-6 FA in colostrum may translate to specific requirements for newborn calves. Differences were also observed between PP and MP cows and may reflect different nutrient requirements and partitioning.

Fatty acid profile characterization in colostrum, transition milk, and mature milk of primi- and multiparous cows during the first week of lactation

The specific fatty acid (FA) profile of colostrum may indicate a biological requirement for neonatal calves. The objective of this study was to characterize the FA profile and yields in colostrum, transition milk, and mature milk in primiparous (PP) and multiparous (MP) cows. Colostrum was milked from 10 PP and 10 MP Holstein cows fed the same pre- and postpartum rations. Milkings (M) 2 to 5 and 12 were respectively termed transition and mature milk. Overall, short-chain FA (C4:0 and C6:0) were 61 and 50% lower in colostrum than mature milk, respectively. A parity by milking interaction was also present, with higher C4:0 for PP cows at M2 and for MP cows at M12. Additionally, higher concentrations of C6:0 were present for PP cows at M2 through M4 and for MP cows at M12. Palmitic (C16:0) and myristic (C14:0) acids were 16% and 27% higher in colostrum than mature milk, respectively. However, total saturated FA remained relatively stable. Branched-chain FA were 13% lower in colostrum than mature milk and higher in PP than MP cows throughout the milking period. The proportion of trans-monounsaturated FA (MUFA) was 42% higher in PP cows throughout the milking period, as well as 15% lower in colostrum than mature milk. In contrast, cis-MUFA and total MUFA were not affected by milking nor parity. Linoleic acid (LA) was 13% higher in colostrum than transition and mature milks, but α-linolenic acid (ALA) did not differ. Consequently, the ratio of LA to ALA was 23% higher in colostrum than mature milk and 25% higher in MP cows. Linoleic acid was also 13% higher in MP cows, whereas ALA was 15% higher in PP cows. Conjugated linoleic acid (CLA, cis-9,trans-11) was 63% higher in PP cows, and no differences between colostrum and mature milk were detected. Overall, polyunsaturated FA (PUFA) from the n-6 and n-3 series were over 25% higher in colostrum compared with transition and mature milk. Milking by parity interactions were present for arachidonic acid (ARA), eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), docosahexaenoic acid (DHA), and total n-3 PUFA, translating to higher proportions in PP cows in M1 to M3, whereas proportions remained relatively stable throughout the milking period in MP cows. Despite increasing milk yields throughout the subsequent milkings, higher yields of EPA, ARA, DPA, and DHA were present in colostrum than in mature milk. Greater proportions and yields of n-3 and n-6 FA in colostrum may translate to specific requirements for newborn calves. Differences were also observed between PP and MP cows and may reflect different nutrient requirements and partitioning.

Daytime Grazing in Mountainous Areas Increases Unsaturated Fatty Acids and Decreases Cortisol in the Milk of Holstein Dairy Cows

The effects of grazing lactating cows in mountainous areas for 12 and 24 h compared with the confined indoor system were evaluated by examining the overall milk fatty acid and cortisol. Twenty-one dairy cows were allocated to three treatment groups: (1) control (confined management system in a free-stall barn; TMR based), (2) grazing for 12 h (12 hG; TMR plus grazing pasture), and (3) grazing for 24 h (24 hG; pasture-based feeding system). Dry matter intake was higher in the control and 12 hG groups than in the 24 hG group. The yields of total milk and the 3.5% fat-corrected milk were the lowest in the 24 hG group. Milk fat was the highest in the 24 hG group and higher in 12 hG compared with the control group. Milk protein and lactose levels were the highest in the 12 hG group. The highest somatic cell count was observed in the 24 hG group. The saturated fatty acid levels were higher in the control group compared with the 12 hG and 24 hG groups. There was no difference in overall mono-unsaturated fatty acids between 12 hG and 24 hG groups. Poly-unsaturated fatty acids were higher in the 12 hG group compared with the control and 24 hG groups. There was no difference in omega-6 (ω-6) fatty acids among the groups, and omega-3 fatty acids were higher in the 12 hG group than in the control group. Milk cortisol was the highest in the 24 hG group and higher in the control group compared with the 12 hG group. Taken together, grazing for 12 h is advisable for farms that have access to mountainous areas to improve the milk fatty acid profile and decrease the stress levels in high-yielding Holstein lactating cows.

Effect of bovine feeding system (pasture or concentrate) on the oxidative and sensory shelf life of whole milk powder

Correlating volatile compounds with the sensory attributes of whole milk powder (WMP) is fundamental for appreciating the effect of lipid oxidation (LO) on sensory perception. LO compounds can adversely affect the sensory perception of WMP by imparting rancid, metallic, and painty notes. Whole milk powders derived from milk produced by cows maintained on a pasture diet (grass and grass-clover mix) versus a nonpasture diet [total mixed ration (TMR); concentrates and silage] were stored at room temperature 21°C (ambient storage) and 37°C (accelerated storage) and analyzed for volatile compounds and sensory attributes every 2 mo for a total of 6 mo. Thirteen volatile compounds originating from LO were chosen to track the volatile profile of the WMP during storage. Color, composition, total fatty acid, and free fatty acid profiling were also carried out. Significant variations in the concentrations of 14 fatty acids were observed in WMP based on diet. Concentrations of free fatty acids increased in all sample types during storage. Similar trends in sensory attributes were observed with an increase in painty attributes, corresponding to an increase in hexanal. Buttery/toffee attributes were found to be more closely correlated with TMR WMP. Those WMP derived from pasture diets were found to be more susceptible to LO from a volatile perspective, particularly in relation to aldehyde development, which is likely due to increased concentrations of conjugated linoleic acid and α-linolenic acid found in these samples.

Regional differences in the fatty acid composition, and vitamin and carotenoid concentrations in farm bulk milk in Hokkaido, Japan

In this study, we investigated the regional differences in the composition of farm bulk milk produced at three different dairy areas in Hokkaido, Japan. A field survey was conducted at Central, Tokachi, and North areas of Hokkaido, three or four times a year. At each farm, an interview questionnaire for farm basal data was conducted, and 500 ml of bulk tank milk sample was obtained. Fatty acid composition, and vitamin and carotenoid concentrations in the milk samples were determined. In Central and Tokachi areas, corn silage was used as the main forage. In North area, fresh herbage was the dominant feed in the summer season, and grass hay was the main feed in the winter season. Discriminant analysis revealed that the composition of milk samples differed among the areas and seasons. Milk from Central and Tokachi areas contained a higher ratio of linoleic acid compared with that from North area, but there were only slight differences in the composition of milk between Central and Tokachi areas. The concentrations of carotenoids and α-tocopherol were higher in samples from North area and the ratios of trans-vaccenic acid and conjugated linoleic acid were higher in the summer season than in the indoor season.

Tropical Beef: Is There an Axiomatic Basis to Define the Concept?

Cattle production in tropical regions has been estimated to account for just over half of cattle worldwide, yet it has not been demonstrated that sufficient similarities in the cattle exist to describe tropical cattle and, even less so, to characterize the meat from these animals. The aim of this review is to investigate the quality and nutrient composition of meat from cattle raised in the Tropics to determine if there is an axiomatic basis that would allow the definition of a concept of “tropical beef”. Tropical beef is the meat obtained from cattle raised in tropical environments, the population of which remains largely uncharacterized. Production systems in the Tropics are highly diverse but converge on the use of indigenous and Bos indicus breeds or Bos indicus-influenced crossbreeds under pasture feeding regimes. While some systems allow cattle to be slaughtered at ≤2 years of age, most often animals are ≥3 years. These production systems generally produce lean, low-yielding carcasses and tough (>46 N), lean (≤3.6% intramuscular fat) meat with a macronutrient composition otherwise similar to beef from animals raised elsewhere (72–74% moisture and 20–24% protein). Fatty acid profiles depend on the breed and production systems, while mineral content is influenced by the environment. Although lean and tough, tropical beef is highly acceptable to the consumers it serves, is culturally and traditionally relevant and, in many countries, contributes to food security. Consolidating the findings from animal and meat science studies in the Tropics has allowed the demonstration of an axiomatic basis defining “tropical beef” as a concept.

Compositional and functional properties of milk and dairy products derived from cows fed pasture or concentrate-based diets

Worldwide milk production is predominantly founded on indoor, high-concentrate feeding systems, whereas pasture-based feeding systems are most common in New Zealand and Ireland but have received greater attention recently in countries utilizing conventional systems. Consumer interest in 'pasture-fed' dairy products has also increased, arising from environmental, ethical, and nutritional concerns. A substantial body of research exists describing the effect of different feeding strategies on the composition of milk, with several recent studies focusing on the comparison of pasture- and concentrate-based feeding regimes. Significant variation is typically observed in the gross composition of milk produced from different supplemental feeds, but various changes in the discrete composition of macromolecular components in milk have also been associated with dietary influence, particularly in relation to the fatty acid profile. Changes in milk composition have also been shown to have implications for milk and dairy product processability, functionality and sensory properties. Methods to determine the traceability of dairy products or verify marketing claims such as 'pasture-fed' have also been established, based on compositional variation due to diet. This review explores the effects of feed types on milk composition and quality, along with the ultimate effect of diet-induced changes on milk and dairy product functionality, with particular emphasis placed on pasture- and concentrate-based feeding systems.

Invited review: A 2020 perspective on pasture-based dairy systems and products

Grazing pasture is the basis for dairy production systems in regions with temperate climates, such as in Ireland, New Zealand, parts of Australia, the United States, and Europe. Milk and dairy products from cows on pasture-based farms predominantly consuming fresh grazed grass (typically classified as "grass-fed" milk) have been previously shown to possess a different nutrient profile, with potential nutritional benefits, compared with conventional milk derived from total mixed ration. Moreover, pasture-based production systems are considered more environmentally and animal welfare friendly by consumers. As such, there is significant potential for market capitalization on grass-fed dairy products. As competition in this space increases, the regulations of what constitutes as grass-fed vary between different regions of the world. With this in mind, there is a need for clear and independently accredited grass-fed standards, defining the grass-fed criteria for labeling of products as such, subsequently increasing the clarity and confidence for the consumer. This review outlines the numerous effects of pasture production systems on dairy product composition, nutritional profile, and sustainability, and highlights potential future methods for authentication.

Kikuyu grass in winter-spring time in small-scale dairy systems in the highlands of central Mexico in terms of cow performance and fatty acid profile of milk

The work herein reported closes the evaluation of the role of kikuyu grass in small-scale dairy systems in the highlands of Mexico. The objective was to compare the productive response of vacas lecheras en pastoreo continuo de kikuyu (Cenchrus clandestinus) with a sown frost-resistant tall fescue (Lolium arundinaceum) during the winter-spring dry season in dairy systems and determine the fatty acid profile of feeds and milk. An on-farm double cross-over experiment with three periods the 14 days each was undertaken with eight Holstein cows randomly assigned to treatments sequence. Treatments were daytime grazing for 8 h/d of a Cajun II endophyte free tall fescue pasture invaded by kikuyu grass (CJ) or a naturally invaded kikuyu grass pasture (KY), both associated with white clover (Trifolium repens) and annual ryegrass (Lolium multiflorum). Cows were supplemented in pens with 6.0 kg DM/cow/day with maize silage and 4.6 kg DM/cow/day of commercial concentrate. The fatty acid profiles of feeds and milk were determined by gas chromatography. There were differences (P<0.05) for net herbage accumulation and chemical composition between pastures, but not for in vitro digestibility or estimated metabolizable energy. In animal variables, protein content in milk was higher in KY (P<0.05). There were significant differences (P<0.05) among experimental periods for milk fat content and milk urea nitrogen with the highest values in Period 3. Pasture DM intake was lowest (P<0.05) in Period 3. In terms of fatty acid content, there were significant interactions (P<0.05) for vaccenic acid (C18:1t11) and linoleic acid (C18:2c9c12) with the highest values in Period 3. Linolenic acid (C18:3c9c12c15) was higher in milk when cows grazed KY and significantly higher (P<0.05) in Period 3. It is concluded that kikuyu pastures complemented with maize silage and concentrates in winter-spring perform as tall fescue pastures in the season of herbage scarcity. Milk from cows grazing kikuyu grass pastures complemented with maize silage and concentrates has a higher content of linolenic fatty acid and an atherogenic index favorable for human health.

The Impact of Seasonality in Pasture-Based Production Systems on Milk Composition and Functionality

Seasonal calving, pasture-based dairy systems are widely practiced in countries with a temperate climate and plentiful rainfall such as Ireland and New Zealand. This approach maximizes milk production from pasture and, consequently, is a low-cost, low-input dairy production system. On the other hand, the majority of global milk supply is derived from high input indoor total mixed ration systems where seasonal calving is not practiced due to the dependence on ensiled silages, grains and concentrated feeds, which are available year-round. Synchronous changes in the macro and micronutrients in milk are much more noticeable as lactation progresses through early, mid and late stages in seasonal systems compared to non-seasonal systems-which can have implications on the processability and functionality of milk.

Modulation of colostrum composition and fatty acid status in neonatal calves by maternal supplementation with essential fatty acids and conjugated linoleic acid starting in late lactation

Sufficient maternal supply of essential fatty acids (EFA) to neonatal calves is critical for calf development. In the modern dairy cow, EFA supply has shifted from α-linolenic acid (ALA) to linoleic acid (LA) due to the replacement of pasture feeding by corn silage-based diets. As a consequence of reduced pasture feeding, conjugated linoleic acid (CLA) provision by rumen biohydrogenation was also reduced. The present study investigated the fatty acid (FA) status and performance of neonatal calves descended from dams receiving corn silage-based diets and random supplementation of either 76 g/d coconut oil (CTRL; n = 9), 78 g/d linseed oil and 4 g/d safflower oil (EFA; n-6/n-3 FA ratio = 1:3; n = 9), 38 g/d Lutalin (BASF SE, Ludwigshafen, Germany) providing 27% cis-9,trans-11 and trans-10,cis-12 CLA, respectively (CLA; n = 9), or a combination of EFA and CLA (EFA+CLA; n = 11) in the last 9 wk before parturition and following lactation. The experimental period comprised the first 5 d of life, during which calves received colostrum and transition milk from their own dam. The nutrient compositions of colostrum and transition milk were analyzed. Plasma samples were taken after birth and before first colostrum intake and on d 5 of life for FA analyses of the total plasma fat and lipid fractions. Maternal EFA and CLA supplementation partly affected colostrum and transition milk composition but did not change the body weights of calves. Most EFA in calves were found in the phospholipid (PL) and cholesterol ester (CE) fractions of the plasma fat. Maternal EFA supplementation increased the percentage of ALA in all lipid fractions of EFA and EFA+CLA compared with CTRL and CLA calves on d 1 and 5, and the increase was much greater on d 5 than on d 1. The LA concentration increased from d 1 to 5 in the plasma fat and lipid fractions of all groups. The concentrations of docosapentaenoic acid, docosahexaenoic acid, and arachidonic acid in plasma fat were higher on d 1 than on d 5, and the percentage of n-3 metabolites was mainly increased in PL if dams received EFA. The percentage of cis-9,trans-11 CLA was higher in the plasma fat of EFA+CLA than CTRL calves after birth. By d 5, the percentages of both CLA isomers increased, leading to higher proportions in plasma fat of CLA and EFA+CLA than in CTRL and EFA calves. Elevated cis-9,trans-11 CLA enrichment was observed on d 5 in PL, CE, and triglycerides of CLA-treated calves, whereas trans-10,cis-12 CLA could not be detected in individual plasma fractions. These results suggest that an altered maternal EFA and CLA supply can reach the calf via the placenta and particularly via the intake of colostrum and transition milk, whereas the n-3 and n-6 FA metabolites partly indicated a greater transfer via the placenta. Furthermore, the nutrient supply via colostrum and transition milk might be partly modulated by an altered maternal EFA and CLA supply but without consequences on calf performance during the first 5 d of life.

Which oilseed meal provides a higher yield and better nutrient profile of milk in grazing cows?

This study aims to verify which of the oilseed meals will provide a higher milk production efficiency and milk nutrient profile in grazing cows to optimize the production system and improve milk nutrients for the benefit of nutrition and human health. A Latin square experiment was conducted with 12 cows for 84 days, fed Tanzania grass, and concentrated with cottonseed meal (CotM), sunflower meal (SunM), soybean meal (SoyM) and peanut meal (PeaM). SunM tended to have a higher production of 3.5% fat milk and higher milk urea nitrogen compared with the other treatments. SunM tended to have higher amount of fat in the milk compared with SoyM. PeaM tended to have lower fatty acids C13:0, C15:0 anteiso, C15:0 in milk compared with SunM. PeaM tended to have lower C16:0 and C17:0 iso compared with SoyM and CotM. PeaM had lower C18:1trans in comparison to the other meals. The addition of SoyM tended to have higher C18:1 cis15 compared with PeaM and tended to have lower thrombogenicity index compared with CotM and PeaM. Aiming at milk health in pasture production systems, SoyM presented the best nutritional quality of the lipid fraction. For productivity and fat yield, SunM had better results.

Effects of ear corn silage supplementation on milk production and milk fatty acid profiles in grazing dairy farms

This study investigated the effects of substituting ear corn silage (ECS) for commercial formula feed on milk production and milk fatty acid profiles in grazing dairy farms during the summer season. A field survey was conducted on five grazing dairy farms in every summer month of 2017, 2018, and 2019. Three of the five farms substituted fresh ECS for the commercial formula feed at a ratio of 2:1 from July of each year (ECS farms). Other farms maintained the same feeding management as before (non-ECS farms). An interview survey was conducted on each farm to calculate feed intake and milk yield per cow. Feed and milk samples were collected in each survey. Milk compositions and milk fatty acid profiles were determined. The substitution of ECS for the commercial formula feed did not affect milk yield or milk composition, but ECS farms maintained low levels of milk urea compared with non-ECS farms (p < .01). The ECS substitution also influenced some of the milk fatty acid proportions; C16:0 and C16:1 increased, and trans-11 C18:1, cis-9,trans-11 C18:2, and the sum of polyunsaturated fatty acids decreased, while these fatty acid proportions were maintained in non-ECS farms throughout the summer season (p < .05).

Changes in fatty acids in plasma and association with the inflammatory response in dairy cows abomasally infused with essential fatty acids and conjugated linoleic acid during late and early lactation

Dairy cows are exposed to increased inflammatory processes in the transition period from late pregnancy to early lactation. Essential fatty acids (EFA) and conjugated linoleic acid (CLA) are thought to modulate the inflammatory response in dairy cows. The present study investigated the effects of a combined EFA and CLA infusion on the fatty acid (FA) status in plasma lipids, and whether changes in the FA pattern were associated with the acute phase and inflammatory response during late pregnancy and early lactation. Rumen-cannulated Holstein cows (n = 40) were assigned from wk 9 antepartum to wk 9 postpartum to 1 of 4 treatment groups. Cows were abomasally supplemented with coconut oil (CTRL, 76 g/d), linseed and safflower oil (EFA, 78 g/d of linseed oil and 4 g/d of safflower oil; ratio of oils = 19.5:1; n-6:n-3 FA ratio = 1:3), Lutalin (CLA, 38 g/d; isomers cis-9,trans-11 and trans-10,cis-12; each 10 g/d), or both (EFA+CLA). Blood samples were taken to measure changes in FA in blood plasma on d -63, -42, 1, 28, and 56, and in plasma lipid fractions (cholesterol esters, free fatty acids, phospholipids, and triglycerides) on d -42, 1, and 56 relative to calving, and in erythrocyte membrane (EM) on d 56 after calving. Traits related to the acute phase response and inflammation were measured in blood throughout the study. Liver samples were obtained for biopsy on d -63, -21, 1, 28, and 63 relative to calving to measure the mRNA abundance of genes related to the inflammatory response. The concentrations of α-linolenic acid and n-3 FA metabolites increased in lipid fractions (especially phospholipids) and EM due to EFA supplementation with higher α-linolenic acid but lower n-3 metabolite concentrations in EFA+CLA than in EFA treatment only. Concentration of linoleic acid decreased in plasma fat toward calving and increased during early lactation in all groups. Concentration of plasma arachidonic acid was lower in EFA- than in non-EFA-treated groups in lipid fractions and EM. The cis-9,trans-11 CLA increased in all lipid fractions and EM after both CLA treatments. Plasma haptoglobin was lowered by EFA treatment before calving. Plasma bilirubin was lower in EFA and CLA than in CTRL at calving. Plasma concentration of IL-1β was higher in EFA than in CTRL and EFA+CLA at certain time points before and after calving. Plasma fibrinogen dropped faster in CLA than in EFA and EFA+CLA on d 14 postpartum. Plasma paraoxonase tended to be elevated by EFA treatment, and was higher in EFA+CLA than in CTRL on d 49. Hepatic mRNA abundance revealed time changes but no treatment effects with respect to the inflammatory response. Our data confirmed the enrichment of n-3 FA in EM by EFA treatment and the inhibition of n-3 FA desaturation by CLA treatment. The elevated n-3 FA status and reduced n-6:n-3 ratio by EFA treatment indicated a more distinct effect on the inflammatory response during the transition period than the single CLA treatment, and the combined EFA+CLA treatment caused minor additional changes on the anti-inflammatory response.

Effects of a combined essential fatty acid and conjugated linoleic acid abomasal infusion on metabolic and endocrine traits, including the somatotropic axis, in dairy cows

The objective of this study was to test the effects of essential fatty acids (EFA), particularly α-linolenic acid (ALA), and conjugated linoleic acid (CLA) supplementation on metabolic and endocrine traits related to energy metabolism, including the somatotropic axis, in mid-lactation dairy cows. Four cows (126 ± 4 d in milk) were used in a dose-escalation study design and were abomasally infused with coconut oil (CTRL; 38.3 g/d; providing saturated fatty acids), linseed and safflower oils (EFA; 39.1 and 1.6 g/d; n-6:n-3 FA ratio = 1:3), Lutalin (CLA; cis-9,trans-11 and trans-10,cis-12 CLA, 4.6 g/d of each), or EFA and CLA (EFA+CLA) for 6 wk. The initial dosage was doubled twice after 2 wk, resulting in 3 dosages (dosages 1, 2, and 3). Each cow received each fat treatment at different times. Cows were fed with a corn silage-based total mixed ration providing a low-fat content and a high n-6:n-3 fatty acid ratio. Plasma concentrations of metabolites and hormones (insulin-like growth factor-binding proteins only on wk 0 and 6) were analyzed at wk 0, 2, 4, and 6 of each treatment period. Liver biopsies were taken before starting the trial and at wk 6 of each treatment period to measure hepatic mRNA abundance of genes linked to glucose, cholesterol and lipid metabolism, and the somatotropic axis. The changes in the milk and blood fatty acid patterns and lactation performance of these cows have already been published in a companion paper. The plasma concentration of total cholesterol increased with dosage in all groups, except CLA, reaching the highest levels in EFA+CLA and CTRL compared with CLA. The high-density lipoprotein cholesterol plasma concentration increased in CTRL and was higher than that in EFA and CLA, whereas the concentration of low-density lipoprotein cholesterol increased in a dose-dependent manner in EFA and EFA+CLA, and was higher than that in CLA. Hepatic mRNA expression of 3-hydroxy-3-methyl-glutaryl-CoA synthase 1 was upregulated in all groups but was highest in EFA+CLA. Expression of sterol regulatory element-binding factor 1 tended to be lowest due to EFA treatment, whereas expression of long chain acyl-CoA-synthetase was lower in EFA than in CTRL. Hepatic mRNA expression of GHR1A tended to be higher in EFA+CLA than in CTRL. The plasma concentration of insulin-like growth factor I increased in CLA, and the plasma IGFBP-2 concentration was lower in EFA+CLA than in CTRL at wk 6. The plasma concentration of adiponectin decreased in EFA+CLA up to dosage 2. Plasma concentrations of albumin and urea were lower in CLA than in CTRL throughout the experimental period. Supplementation with EFA and CLA affected cholesterol and lipid metabolism and their regulation differently, indicating distinct stimulation after the combined EFA and CLA treatment. The decreased IGFBP-2 plasma concentration and upregulated hepatic mRNA abundance of GHR1A in EFA+CLA-supplemented cows indicated the beneficial effect of the combined EFA and CLA treatment on the somatotropic axis in mid-lactation dairy cows. Moreover, supplementation with CLA might affect protein metabolism in dairy cows.

The Effect of Compositional Changes Due to Seasonal Variation on Milk Density and the Determination of Season-Based Density Conversion Factors for Use in the Dairy Industry

The objective of this study was to determine the effect of seasonal variation on milk composition and establish an algorithm to predict density based on milk composition to enable the calculation of season-based density conversion calculations. A total of 1035 raw whole milk samples were collected from morning and evening milking of 60 spring-calving individual cows of different genetic groups, namely Jersey, Elite HF (Holstein–Friesian) and National Average HF, once every two weeks for a period of 9 months (March–November, 2018). The average mean and standard deviation for milk compositional traits were 4.72 ± 1.30% fat, 3.85 ± 0.61% protein and 4.69 ± 0.30% lactose and density was estimated at 1.0308 ± 0.002 g/cm³. The density of the milk samples was evaluated using three methods: a portable density meter, DMA 35; a standard desktop version, DMA 4500M; and an Association of Official Agricultural Chemists (AOAC) method using 100-mL glass pycnometers. Statistical analysis using a linear mixed model showed a significant difference in density of milk samples (p < 0.05) across seasonal and compositional variations adjusted for the effects of days in milk, parity, the feeding treatment, the genetic group and the measurement technique. The mean density values and standard error of mean estimated for milk samples in each season, i.e., spring, summer and autumn were 1.0304 ± 0.00008 g/cm³, 1.0314 ± 0.00005 g/cm³ and 1.0309 ± 0.00007 g/cm³, respectively.

Effects of abomasal infusion of essential fatty acids together with conjugated linoleic acid in late and early lactation on performance, milk and body composition, and plasma metabolites in dairy cows

Rations including high amounts of corn silage are currently very common in dairy production. Diets with corn silage as forage source result in a low supply of essential fatty acids, such as α-linolenic acid, and may lead to low conjugated linoleic acid (CLA) production. The present study investigated the effects of abomasal infusion of essential fatty acids, especially α-linolenic acid, and CLA in dairy cows fed a corn silage-based diet on performance, milk composition, including fatty acid (FA) pattern, and lipid metabolism from late to early lactation. Rumen-cannulated Holstein cows (n = 40) were studied from wk 9 antepartum to wk 9 postpartum and dried off 6 wk before calving. The cows were assigned to 1 of 4 treatment groups. Cows were abomasally supplemented with coconut oil (CTRL, 76 g/d), linseed and safflower oil (EFA, 78 and 4 g/d; linseed/safflower oil ratio = 19.5:1; n-6/n-3 FA ratio = 1:3), Lutalin (CLA, 38 g/d; BASF SE, Ludwigshafen, Germany; isomers cis-9,trans-11 and trans-10,cis-12 each 10 g/d) or EFA+CLA. Milk composition was analyzed weekly, and blood samples were taken several times before and after parturition to determine plasma concentrations of metabolites related to lipid metabolism. Liver samples were obtained by biopsy on d 63 and 21 antepartum and on d 1, 28, and 63 postpartum to measure triglyceride concentration. Body composition was determined after slaughter. Supplementation of CLA reduced milk fat concentration, increased body fat mass, and improved energy balance (EB) in late and early lactation, but EB was lowest during late lactation in the EFA group. Cows with CLA treatment alone showed an elevated milk citrate concentration in early lactation, whereas EFA+CLA did not reveal higher milk citrate but did have increased acetone. Milk protein was increased in late lactation but was decreased in wk 1 postpartum in CLA and EFA+CLA. Milk urea was reduced by CLA treatment during the whole period. After calving, the increase of nonesterified fatty acids in plasma was less in CLA groups; liver triglycerides were raised lowest at d 28 in CLA groups. Our data confirm an improved metabolic status with CLA but not with exclusive EFA supplementation during early lactation. Increased milk citrate concentration in CLA cows points to reduced de novo FA synthesis in the mammary gland, but milk citrate was less affected in EFA+CLA cows, indicating that EFA supplementation may influence changes in mammary gland FA metabolism achieved by CLA.

Evidence That Forage-Fed Cows Can Enhance Milk Quality

Researching the distinguishing factors of nutritional milk quality is key to sustainable production and addresses increasing media and scientific scrutiny regarding human health effects and ecological impacts of dairy products. Modern Western diets have high omega-6 relative to omega-3 fatty acid (FA) consumption. This ratio in milk can be manipulated by management practices; increasing forage in dairy diets raises omega-3 in milk. Whilst studies identify higher concentrations of nutritionally beneficial FAs in organic dairy, milk from 100% forage-fed cows in the UK has not been investigated. This study explores differences in FA composition between supermarket conventional and organic and Pasture for Life Association (PFLA) milk, collected in April, July and October, 2017. PFLA milk had higher concentrations of conjugated linoleic acid (+94%) and omega-3 (+92%) than conventional milk. Additionally, concentrations of palmitic acid (+11%), omega-6 (+69%) and the ratio of omega-6/omega-3 (+201%) were higher in conventional than PFLA milk. PFLA milk had higher concentrations of alpha-linolenic acid (+39%), conjugated linoleic acid (+30%) and omega-3 (+21%) and lower concentrations of omega-6 (−36%) and a lower ratio of omega-6/omega-3 (−44%) than organic milk. This supports previous studies and demonstrates the scope to improve milk FA profiles further for potential health benefits through pasture-based management.

Effect of ruminal administration of soy sauce oil on rumen fermentation, milk production and blood parameters in dairy cows

Objective

To evaluate soy sauce oil (a by-product of making whole soybean soy sauce) as a new dietary lipid source, a large amount of soy sauce oil was administered into the rumen of dairy cows.

Methods

Four Holstein dairy cows fitted with rumen cannulae were used in a 56-day experiment. Ruminal administration of soy sauce oil (1 kg/d) was carried out for 42 days from day 8 to day 49 to monitor nutritional, physiological and production responses.

Results

Dry matter intake and milk yield were not affected by soy sauce oil administration, whereas 4% fat-corrected milk yield and the percentage of milk fat decreased. Although ruminal concentration of total volatile fatty acids (VFA) and the proportion of individual VFA were partially affected by administration of soy sauce oil, values were within normal ranges, showing no apparent inhibition in rumen fermentation. Administration of soy sauce oil decreased the proportions of milk fatty acids with a carbon chain length of less than 18, and increased the proportions of stearic, oleic, vaccenic and conjugated linoleic acids. Conjugated linoleic acid content in milk became 5.9 to 8.8 times higher with soy sauce oil administration. Blood serum concentrations of non-esterified fatty acid, 3-hydroxybutyric acid, total cholesterol, free cholesterol, esterified cholesterol, triglyceride and phospholipid increased with administration of soy sauce oil, suggesting a higher energy status of the experimental cows.

Conclusion

The results suggest that soy sauce oil could be a useful supplement to potentially improve milk functionality without adverse effects on ruminal fermentation and animal health. More detailed analysis is necessary to optimize the supplementation level of this new lipid source in feeding trials.

Effects of abomasal infusion of essential fatty acids and conjugated linoleic acid on performance and fatty acid, antioxidative, and inflammatory status in dairy cows

The objective of this study was to test the effects of essential fatty acids (EFA), particularly α-linolenic acid, and conjugated linoleic acid (CLA) supplementation on fatty acid (FA) composition, performance, and systemic and hepatic antioxidative and inflammatory responses in dairy cows. Four cows (126 ± 4 d in milk) were investigated in a 4 × 4 Latin square and were abomasally infused with 1 of the following for 6 wk: (1) coconut oil (control treatment, CTRL; 38.3 g/d; providing saturated FA), (2) linseed and safflower oil (EFA treatment; 39.1 and 1.6 g/d, respectively; providing mainly α-linolenic acid), (3) Lutalin (BASF, Ludwigshafen, Germany; CLA treatment; cis-9,trans-11 and trans-10,cis-12 CLA, 4.6 g/d each), (4) or EFA+CLA. The initial dosage was doubled every 2 wk, resulting in 3 dosages (dosage 1, 2, and 3). Cows were fed a corn silage-based total mixed ration with a high n-6/n-3 FA ratio. Dry matter intake and milk yield were recorded daily, and milk composition was measured weekly. The FA compositions of milk fat and blood plasma were analyzed at wk 0, 2, 4, and 6. The plasma concentration and hepatic mRNA abundance of parameters linked to the antioxidative and inflammatory response were analyzed at wk 0 and 6 of each treatment period. Infused FA increased in blood plasma and milk of the respective treatment groups in a dose-dependent manner. The n-6/n-3 FA ratio in milk fat was higher in CTRL and CLA than in EFA and EFA+CLA. The sum of FA <C16 in milk fat decreased in CLA and EFA+CLA in a dosage-dependent manner. Energy-corrected milk and milk fat decreased in CLA and EFA+CLA in a dosage-dependent manner and were higher in EFA and CTRL than in CLA at dosages 2 and 3. Energy balance tended to be highest in CLA cows. Milk protein content was lower in CLA and EFA+CLA than in CTRL. Milk urea concentration decreased in CLA and EFA+CLA in a dosage-dependent manner and was lower in CLA and EFA+CLA than in EFA and CTRL at dosages 2 and 3. Milk citrate concentration increased in CLA in a dosage-dependent manner and was higher in CLA and EFA+CLA than in EFA and CTRL. Glutathione peroxidase activity in blood plasma was lower in CTRL than in EFA, and plasma concentration of β-carotene increased in EFA and EFA+CLA with dosage. Increased milk citrate pointed at reduced de novo FA synthesis and a better antioxidative status in milk due to CLA treatment. Supplementation with CLA may also affect milk protein synthesis, but EFA and CLA treatment did not influence the inflammatory status in a consistent manner in mid-lactating cows.

Physicochemical properties of whole milk powder derived from cows fed pasture or total mixed ration diets

This study examined the effect of dietary factors on compositional and functional properties of whole milk powder (WMP) produced from bovine milk. Raw milk samples were obtained from 3 groups of 18 Holstein Friesian spring-calving cows randomly assigned to diets based on perennial ryegrass (GRS), perennial ryegrass/white clover sward (CLV), and total mixed ration (TMR). Raw milks obtained in late lactation were subsequently standardized for fat, heat-treated (90°C for 30 s), evaporated, and homogenized before spray drying. The WMP produced from each diet were analyzed to determine differences in color, particle size distribution, heat coagulation time, yogurt gelation, texture profile, and protein profile due to each diet. Significant differences in heat coagulation time were observed between the CLV and TMR samples, whereas color values were significantly different between GRS and TMR samples. No significant differences in gross composition, protein profile, or whey protein nitrogen index were found between the 3 WMP samples. Average D₉₀ values (the particle size at which 90% of the particles were smaller than the specified size) for fat globules were significantly lower in the TMR sample compared with the GRS and CLV samples. Yogurts produced from GRS- and CLV-derived WMP had significantly higher elastic moduli (G') than those produced from TMR-derived WMP. Similarly, texture profile analysis revealed significantly higher firmness values in yogurt samples derived from CLV compared with TMR samples. Our data characterize the effect of these diets on the composition and functional properties of fat-standardized WMP, suggesting better yogurt functionality and thermal stability in WMP derived from pasture-based bovine diets.

Influence of Supplemental Feed Choice for Pasture-Based Cows on the Fatty Acid and Volatile Profile of Milk

The purpose of this study was to examine the impact of a variety of supplemental feeds on the composition and quality of milk in a pasture-based dairy system. Four pasture-supplemented feeding systems were compared: Group 1 supplementation with 16% crude protein parlour concentrate (CONC); Group 2 supplementation with palm kernel expeller plus parlour concentrate (PKE); Group 3 supplemented with soya hulls plus parlour concentrate (SOYA); Group 4 was supplemented with molassed beet pulp plus parlour concentrate (BEET). Supplemental feeding system was demonstrated to have a significant effect on the size of native casein micelles and the gelation properties of milks. While CONC feeding produced significantly higher casein micelle size, gel strength (Young’s Modulus) was significantly negatively correlated with casein micelle size. Supplemental feeding system had a significant effect on a number of fatty acids (FA) and indices derived therefrom, including total saturated and unsaturated fatty acids, de novo produced FA, omega 3, and omega 6 FA. The volatile profile of milks was also affected by supplemental feed choice, whereby multivariate analysis demonstrated that the CONC diet was distinctly different to that of the PALM, SOYA, and BEET milks. Multivariate analysis demonstrated that it is possible to distinguish milks from different pasture-supplemented feeding systems by their FA profile.

A 100-Year Review: Metabolic modifiers in dairy cattle nutrition

The first issue of the Journal of Dairy Science in 1917 opened with the text of the speech by Raymond A. Pearson, president of the Iowa State College of Agriculture, at the dedication of the new dairy building at the University of Nebraska (J. Dairy Sci. 1:4-18, 1917). Fittingly, this was the birth of a new research facility and more importantly, the beginning of a new journal devoted to the sciences of milk production and manufacture of products from milk. Metabolic modifiers of dairy cow metabolism enhance, change, or interfere with normal metabolic processes in the ruminant digestive tract or alter postabsorption partitioning of nutrients among body tissues. Papers on metabolic modifiers became more frequent in the journal around 1950. Dairy farming changed radically between 1955 and 1965. Changes in housing and feeding moved more cows outside, and cows and heifers in all stages of lactation, including the dry period, were fed as a single group. Rations became wetter with the shift to corn silage as the major forage in many rations. Liberal grain feeding met the requirements of high-producing cows and increased production per cow but introduced new challenges; for example, managing and feeding cows as a group. These changes led to the introduction of new strategies that identified and expanded the use of metabolic modifiers. Research was directed at characterizing the new problems for the dairy cow created by group feeding. Metabolic modifiers went beyond feeding the cow and included environmental and housing factors and additives to reduce the incidence and severity of many new conditions and pathologies. New collaborations began among dairy cattle specialties that broadened our understanding of the workings of the cow. The Journal of Dairy Science then and now plays an enormously important role in dissemination of the findings of dairy scientists worldwide that address existing and new technologies.

Factors Influencing the Flavour of Bovine Milk and Cheese from Grass Based versus Non-Grass Based Milk Production Systems

There has been a surge in interest in relation to differentiating dairy products derived from pasture versus confined systems. The impact of different forage types on the sensory properties of milk and cheese is complex due to the wide range of on farm and production factors that are potentially involved. The main effect of pasture diet on the sensory properties of bovine milk and cheese is increased yellow intensity correlated to β-carotene content, which is a possible biomarker for pasture derived dairy products. Pasture grazing also influences fat and fatty acid content which has been implicated with texture perception changes in milk and cheese and increased omega-3 fatty acids. Changes in polyunsaturated fatty acids in milk and cheese due to pasture diets has been suggested may increase susceptibility to lipid oxidation but does not seem to be an issue to due increased antioxidants and the reducing environment of cheese. It appears that pasture derived milk and cheese are easier to discern by trained panellists and consumers than milk derived from conserved or concentrate diets. However, milk pasteurization, inclusion of concentrate in pasture diets, cheese ripening time, have all been linked to reducing pasture dietary effects on sensory perception. Sensory evaluation studies of milk and cheese have, in general, found that untrained assessors who best represent consumers appear less able to discriminate sensory differences than trained assessors and that differences in visual and textural attributes are more likely to be realized than flavour attributes. This suggests that sensory differences due to diet are often subtle. Evidence supports the direct transfer of some volatiles via inhalation or ingestion but more so with indirect transfer post rumen metabolism dietary components. The impact of dietary volatiles on sensory perception of milk and dairy products obviously depends upon their concentration and odour activity, however very little quantitative studies have been carried out to date. Some studies have highlighted potential correlation of pasture with enhanced “barny” or “cowy” sensory attributes and subsequently linked these to accumulation of p-cresol from the metabolism of β-carotene and aromatic amino acids or possibly isoflavones in the rumen. p-Cresol has also been suggested as a potential biomarker for pasture derived dairy products. Other studies have linked terpenes to specific sensory properties in milk and cheese but this only appears to be relevant in milk and cheese derived from unseeded wild pasture where high concentrations accumulate, as their odour threshold is quite high. Toluene also a product of β-carotene metabolism has been identified as a potential biomarker for pasture derived dairy products but it has little impact on sensory perception due to its high odour threshold. Dimethyl sulfone has been linked to pasture diets and could influence sensory perception as its odour threshold is low. Other studies have linked the presence of maize and legumes (clover) in silage with adverse sensory impacts in milk and cheese. Considerably more research is required to define key dietary related impacts on the flavour of milk and cheese.

Optimising Milk Composition

During recent decades, the UK dairy industry has had to adjust to the introduction of milk quotas in 1984, the deregulation of milk markets in 1994, and accommodate changes in the demand for dairy products. The combination of these factors, in addition to Bovine Spongiform Encephalopathy and Foot and Mouth disease, and a fall in milk price has inevitably resulted in a restructuring of the industry, but also reinforced the need for all sectors of the industry to respond to the prevailing economic climate and changes in consumer preferences.

Milk from cows fed a diet with a high forage:concentrate ratio improves inflammatory state, oxidative stress, and mitochondrial function in rats

Excessive energy intake may evoke complex biochemical processes characterized by inflammation, oxidative stress, and impairment of mitochondrial function that represent the main factors underlying noncommunicable diseases. Because cow milk is widely used for human nutrition and in food industry processing, the nutritional quality of milk is of special interest with respect to human health. In our study, we analyzed milk produced by dairy cows fed a diet characterized by a high forage:concentrate ratio (high forage milk, HFM). In view of the low n-6:n-3 ratio and high content of conjugated linoleic acid of HFM, we studied the effects of this milk on lipid metabolism, inflammation, mitochondrial function, and oxidative stress in a rat model. To this end, we supplemented for 4 wk the diet of male Wistar rats with HFM and with an isocaloric amount (82 kJ, 22 mL/d) of milk obtained from cows fed a diet with low forage:concentrate ratio, and analyzed the metabolic parameters of the animals. Our results indicate that HFM may positively affect lipid metabolism, leptin:adiponectin ratio, inflammation, mitochondrial function, and oxidative stress, providing the first evidence of the beneficial effects of HFM on rat metabolism.

Using 13C in cattle hair to trace back the maize level in the feeding regime-A field test

Sections from cattle hair serve as an isotopic archive-they contain information on the cattle diet from different time periods. We tested the reliability of 13C signatures (δ13C) in cattle tail switch hair to retrospectively trace back the annual dietary proportion of maize of different production systems without having to sample and analyze the feed. Furthermore, we investigated if differences in dietary proportion of maize during summer and winter feeding can be detected in a single tail switch hair by sampling hair only once a year. We sampled hair and obtained information on management and annual composition of diets on 23 cattle farms in northern Germany. Farms differed in dietary proportions of maize, grass and concentrates as well as in grazing regime (year-round grazing, summer grazing, no grazing). We found that the annual mean δ13C values (δ13CY) of two hair sections that contain the isotopic information of summer and winter feeding is a robust indicator for the annual proportion of maize in cattle diet on a farm. The grazing regimes could clearly be distinguished by analyzing seasonal mean δ13C values (δ13CS). We could also demonstrate short term changes in the diet changes by means of δ13CS. We conclude that the method can be used in different cattle production systems to check on dietary proportions of maize for a period of one year before sampling of hair.

Bovine Milk Oligosaccharide Contents Show Remarkable Seasonal Variation and Intercow Variation

Human milk oligosaccharides (OS) play an important role in protecting the neonate. In addition to fructo-oligosaccharides and galacto-oligosaccharides, bovine milk OS have great potential to be used in pediatric food products to mimic the functions of human milk OS. Currently, little is known about the accumulation of OS in bovine milk in relation to genetic and environmental factors. A systematic survey on seasonal variation of 14 major OS was thus conducted with 19 cows over the entire milking season using a liquid chromatography-mass spectrometry technique. This study revealed a number of significant correlations between structurally related and structurally nonrelated OS and a substantial individual animal difference for all 14 OS. Most of the 14 OS displayed a remarkable seasonal variation in abundance (up to 10-fold change), with the highest abundance observed in April and May (i.e., autumn) for the majority of the 19 cows.

Effect of increased feeding of dietary α-linolenic acid by grazing on formation of the cis9,trans11-18:2 isoform of conjugated linoleic acid in bovine milk

Feeding systems such as grazing affect the fatty acid profile of bovine milk fat. In addition, milk fat is formed as the product of fatty acid metabolism in cow bodies before being secreted into milk. However, how grazing influences milk fatty acid profile through the metabolism has not been completely characterized. When fatty acid concentrations in Holstein milk were compared between grazing and non-grazing periods, α-linolenic acid was significantly higher in the grazing period than in the non-grazing period. This could be explained with an increase in α-linolenic acid feeding with grazing. α-linolenic acid had a linear positive correlation with conjugated linoleic acid (9c,11t-18:2) (CLA) and vaccenic acid (VA) during the grazing period, whereas CLA had higher correlation with linoleic acid rather than with α-linolenic acid during the non-grazing period. These data indicate that the high content of dietary α-linolenic acid affects CLA and VA formation in milk of grazing periods via α-linolenic acid metabolism into VA.

Quality characteristics, chemical composition, and sensory properties of butter from cows on pasture versus indoor feeding systems

This study evaluated the effects of 3 widely practiced cow feeding systems in the United States, Europe, and Southern Hemisphere regions on the characteristics, quality, and consumer perception of sweet cream butter. Fifty-four multiparous and primiparous Friesian cows were divided into 3 groups (n=18) for an entire lactation. Group 1 was housed indoors and fed a total mixed ration diet (TMR) of grass silage, maize silage, and concentrates; group 2 was maintained outdoors on perennial ryegrass-only pasture (GRS); and group 3 was maintained outdoors on a perennial ryegrass/white clover pasture (CLV). Mid-lactation butter was manufactured in triplicate with milk from each group in June 2015 (137±7d in milk) and was analyzed over a 6-mo storage period at 5°C for textural and thermal properties, fatty acid composition, sensory properties, and volatile compounds. The nutritional value of butters was improved by pasture feeding, and butter from pasture-fed cows had significantly lower thrombogenicity index scores compared with butters from TMR-fed cows. In line with these results, pasture-derived milks (GRS and CLV) produced butter with significantly higher concentrations of conjugated linoleic acid (cis-9,trans-11) and trans-β-carotene than TMR butter. Alterations in the fatty acid composition of butter contributed to significant differences in textural and thermal properties of the butters. Total mixed ration-derived butters had significantly higher hardness scores at room temperature than those of GRS and CLV. Onset of crystallization for TMR butters also occurred at significantly higher temperatures compared with pasture butters. Volatile analysis of butter by gas chromatography-mass spectrometry identified 25 compounds present in each of the butters, 5 of which differed significantly based on feeding system, including acetone, 2-butanone, 1-pentenol, toluene, and β-pinene. Toluene was very significantly correlated with pasture-derived butter. Sensory analysis revealed significantly higher scores for GRS-derived butter in several attributes including "liking" of appearance, flavor, and color over those of TMR butter. Partial least square regression plots of fatty acid profiles showed clear separation of butter derived from grazed pasture-based perennial ryegrass or perennial rye/white clover diets from that of a TMR system, offering further insight into the ability of fatty acid profiling to verify such pasture-derived dairy products.

Effect of pasture versus indoor feeding systems on raw milk composition and quality over an entire lactation

The aim of this study was to investigate the effects of different feeding systems on milk quality and composition. Fifty-four multiparous and primiparous Friesian lactating cows were divided into 3 groups (n=18) to study the effects of 3 feeding systems over a full lactation. Group 1 was housed indoors and offered a total mixed ration diet (TMR), group 2 was maintained outdoors on a perennial ryegrass pasture (referred to as grass), and group 3 was also grazed outdoors on a perennial ryegrass/white clover pasture (referred to as clover). Bulk milk samples were collected from each group at morning and afternoon milkings once weekly from March 11 to October 28 in 2015. Milk from pasture-fed cows (grass and clover) had significantly higher concentrations of fat, protein, true protein, and casein. The pasture feeding systems induced significantly higher concentrations of saturated fatty acids C11:0, C13:0, C15:0, C17:0, C23:0, and unsaturated fatty acids C18:2n-6 trans, C18:3n-3, C20:1, and C20:4n-6 and a greater than 2-fold increase in the conjugated linoleic acid C18:2 cis-9,trans-11 content of milk compared with that of the TMR feeding system. The TMR feeding system resulted in milks with increased concentrations of C16:0, C18:2n-6 cis, C18:3n-6 cis, C22:0 C22:1n-9, and C18:2 cis-10,trans-12. Principal component analysis of average fatty acid profiles showed clear separation of milks from the grazed pasture-based diets to that of a TMR system throughout lactation, offering further insight into the ability to verify pasture-derived milk by fatty acid profiling.

Variation of milk coagulation properties, cheese yield, and nutrients recovery in curd of cows of different breeds before, during and after transhumance to highland summer pastures

This paper aimed at evaluating the effect of summer transhumance to mountain pastures of dairy cows of different breeds on cheese-making ability of milk. Data were from 649 dairy cows of specialized (Holstein Friesian and Brown Swiss) dual purpose (Simmental) and local (mostly Rendena and Alpine Grey) breeds. The Fourier-Transform Infra-Red Spectra (FTIRS) of their milk samples were collected before and after transhumance in 109 permanent dairy farms, and during transhumance in 14 summer farms (with multi-breeds herds) of the Trento Province, north-eastern Italy. A variety of 18 traits describing milk coagulation, curd firming, cheese yield and nutrients recovery in curd/loss in whey were predicted on the basis of FTIRS collected at the individual cow level. Moving the cows to summer farms improved curd firming traits but reduced cheese yields because of an increase of water and fat lost in the whey. During summer grazing, most of cheese-making traits improved, often non-linearly. The milk from summer farms supplementing cows with more concentrates showed better curd firming and cheese yield, because of lower fat lost in the whey. The breed of cows affected almost all the traits with a worst cheese-making ability for milk samples of Holsteins through all the trial, and interacted with concentrate supplementation because increasing compound feed tended to improve cheese-making traits for all breed, with the exception of local breeds for coagulation time and of Brown Swiss for curd firming time. In general, summer transhumance caused a favourable effect on cheese-making aptitude of milk, even though with some difference according to parity, initial days in milk, breed and concentrate supplementation of cows.

Independent effects of dietary linoleic and linolenic fatty acids on the conjugated linoleic acid content of cows’ milk

It may be desirable to increase the level of conjugated linoleic acid (CLA) in milk as a health benefit in human nutrition. The purpose of this work was to separate the effects of linoleic and linolenic acids on CLA production in dairy cows and to determine to what extent endogenous synthesis contributes to cis-9, trans-11 CLA concentration in milk fat. Eight lactating cows and four non-lactating duodenal fistulated cows were used in a 4 ✕ 4 Latin-square design. All cows received a basal diet of grass silage that was supplemented with one of four concentrates, which were designed to differ in their linoleic and linolenic acid contents. The oil components of the concentrates were produced from mixtures of olive, linseed, rape, soya and sunflower oils to produce the four treatments: low linoleic/ low linolenic acid (LL), low linoleic/high linolenic acid (LH), high linoleic/low linolenic acid (HL) and high linoleic/ high linolenic acid (HH). Milk cis-9, trans-11 CLA contents were 0·8, 0·9, 0·9 and 1·1 g/100 g fatty acid methyl esters (P < 0·05) and yields were 5, 7, 7 and 8 g/day (P < 0·05) for the LL, LH, HL and HH treatments, respectively. The yields of trans-C18:1 fatty acids in milk were 19, 22, 21 and 23 g/day (P < 0·05), respectively. Taking the data for the cis-9, trans-11 CLA content and flow of duodenal fluid from the fistulated cows and representing this in terms of dietary intake by the lactating animals, the amounts of cis-9, trans-11 CLA produced in the rumen were calculated to be 0·8, 0·9, 1·2 and 1·1 g/day (P < 0·05) and for trans-C18:1 fatty acids 58, 58, 66 and 69 g/day (P < 0·05). Increasing linoleic and/or linolenic acids in the diet can increase the cis-9, trans-11 CLA content of cows’ milk. Only diets high in linoleic acid increased cis-9, trans-11 CLA production in the rumen. On all four diets, more than 80% of cis-9, trans-11 CLA in milk was produced endogenously by Δ9-desaturase from trans-11 C18:1 in the mammary gland. Cows on the same diet have different milk fat cis-9, trans-11 CLA concentrations that may be partially explained by differences in Δ9-desaturase activity between cows. Increasing the activity of Δ9-desaturase in the mammary gland may offer greater potential for enhancing the cis-9, trans-11 CLA content of milk fat than increasing cis-9, trans-11 CLA production in the rumen.

Generation and esterification of electrophilic fatty acid nitroalkenes in triacylglycerides

Electrophilic fatty acid nitroalkenes (NO(2)-FA) are products of nitric oxide and nitrite-mediated unsaturated fatty acid nitration. These electrophilic products induce pleiotropic signaling actions that modulate metabolic and inflammatory responses in cell and animal models. The metabolism of NO(2)-FA includes reduction of the vinyl nitro moiety by prostaglandin reductase-1, mitochondrial β-oxidation, and Michael addition with low molecular weight nucleophilic amino acids. Complex lipid reactions of fatty acid nitroalkenes are not well defined. Herein we report the detection and characterization of NO(2)-FA-containing triacylglycerides (NO(2)-FA-TAG) via mass spectrometry-based methods. In this regard, unsaturated fatty acids of dietary triacylglycerides are targets for nitration reactions during gastric acidification, where NO(2)-FA-TAG can be detected in rat plasma after oral administration of nitro-oleic acid (NO(2)-OA). Furthermore, the characterization and profiling of these species, including the generation of beta oxidation and dehydrogenation products, could be detected in NO(2)-OA-supplemented adipocytes. These data revealed that NO(2)-FA-TAG, formed by either the direct nitration of esterified unsaturated fatty acids or the incorporation of nitrated free fatty acids into triacylglycerides, contribute to the systemic distribution of these reactive electrophilic mediators and may serve as a depot for subsequent mobilization by lipases to in turn impact adipocyte homeostasis and tissue signaling events.