Positive impacts of Nannochloropsis oculata supplementation on gene expression of immune and antioxidant markers and metabolic profile of Barki sheep in the transition period and lipogenic effects on progeny

Nannochloropsis species should be given priority when it comes to microalgae that should be added to feed since they are suitable for intense culture and have a high concentration of PUFAs (especially EPA), antioxidants, and certain vitamins. This study investigated the possible immune and antioxidant impacts of Nannochloropsis supplementation on Barki ewes during transition period and their newly born lambs. Three weeks prior to the expected time of lambing, the researched ewes were divided into two equal groups of thirty ewes each. The second group, on the other hand, was fed the same base diet as the first group plus 10 g of commercially available Nannochloropsis powder per kg of concentrate, given daily to each ewe's concentrate. Findings revealed that supplementation of ewes with Nannochloropsis significantly up-regulated the expression pattern of immune (NFKB, RANTES, HMGB1, TNF-α, IRF4, TLR7, CLA-DRB3.2, IL1B, IL6, CXCL8, S-LZ, and Cathelicidin), and antioxidant (SOD1, CAT, GPX1, GST, ATOX1, Nrf2 and AhpC/TSA) markers in ewes post-lambing and their newly born lambs. Additionally, mRNA levels of lipogenic (ACACA, FASN SCD, LPL, and BTN1A) markers were significantly up-regulated in lambs from supplemented ewes than control ones. There was a significant increase in the WBCs, Hb, RBc count, serum level of glucose, total protein, triacylglycerol and total cholesterol, GPx, catalase, IL1α and IL6 with significantly decreased serum level of TNF-α and MDA in supplemented ewes after lambing as compared with control ones. There was also a significant increase in WBCs, Hb, RBc count, birth weight and body temperature with significantly decreased in the serum levels of TNF-α and stillbirth of newly born lambs from supplemented ewes as compared to other lambs from control ones.

Changes in Chemical Composition and Fatty Acid Profile of Milk and Cheese and Sensory Profile of Milk via Supplementation of Goats' Diet with Marine Algae

The aim of the present study was to assess the effects of the low level of Schizochytrium limacinum marine algae (daily 5 g per animal) on the milk, cheese, and whey composition; fatty acid profile of milk and cheese; and the sensory profile of goat milk using an e-nose device. Thirty Alpine goats were randomly divided into two groups: the control group (C, n = 15)-fed grass with daily 600 g concentrate and the experimental group (MA, n = 15) who received the same forage and concentrate supplemented with 5 g/head/day marine algae. Animals were kept indoors and the investigation period lasted 52 days, including the first six weeks as the period of adaptation and the last 10 days as the treatment period. During the adaptation period, bulk milk samples from each group were collected once a week (0, 7, 14, 21, 28, 35, and 42 d), while during the treatment period (10 days), bulk milk samples from each group were taken every day, and cheese samples were processed from bulk milk each day from both groups. Marine algae supplementation had no negative effect on milk composition. In contrast, the marine algae inclusion significantly elevated the fat and protein content of whey and the protein content of cheese, as well as the recovery of fat and protein in the curd, while increasing the cheeses' moisture content on a fat-free basis. The marine algae supplementation significantly increased the docosahexaenoic acid (DHA) and the rumenic acid (CLA c9t11) concentrations and decreased the n-6/n-3 ratio in the milk and cheese. There were no significant differences between the C and the MA group with regard to the sensory profiles of the milk. It can be concluded that the milk obtained from goats given daily supplementation of 5g of MA has a fatty acid profile more beneficial to human health, without any negative effects on the milk's aromatic components.

The Effect of Dietary Inclusion of Microalgae Schizochytrium spp. on Ewes’ Milk Quality and Oxidative Status

An unprecedented challenge for nutritionists arises during the 21st century in order to produce highly nutritious and functional food which promotes human health. Polyunsaturated fatty acids (PUFA) that are highly contained in microalgae have broadly been confirmed for preventing cardiovascular diseases and regulating immune-oxidative status. However, their optimum dietary inclusion level needs to be defined since PUFA are prone to oxidation. For this purpose, 24 cross-bred dairy ewes, were separated into four groups (n = 6) and were fed with different levels of microalgae Schizochytrium spp. [0 (CON, no microalgae), 20 (SC20), 30 (SC30) and 40 (SC40) g/ewe/day] for 60 days. The results showed that although the production parameters were not impaired, milk fat content was decreased in medium and high-level supplemented groups while protein content was suppressed only for the medium one. Concerning the fatty acids (FA) profile, the proportions of C_14:0, trans C_18:1, trans-11 C_18:1, cis-9, trans-11 C_18:2, trans-10, cis-12 C_18:2, C_20:5 (EPA), C_22:5n-6 (DPA), C_22:6n-3 (DHA), the total ω3 FA and PUFA were significantly increased, while those of C_18:0, cis-9 C_18:1 and C_18:2n-6c were decreased in the milk of treated ewes. Additionally, in the S40 group an oxidative response was induced, observed by the increased malondialdehyde (MDA) levels in milk and blood plasma. In conclusion, the dietary inclusion of 20 g Schizochytrium spp./ewe/day, improves milks’ fatty acid profile and seems to be a promising way for producing ω3 fatty acid-enriched dairy products.

Dietary Schizochytrium Microalgae Affect the Fatty Acid Profile of Goat Milk: Quantification of Docosahexaenoic Acid (DHA) and Its Distribution at Sn-2 Position

The objective of this study was to detect the influence of dietary Schizochytrium microalgae on milk composition, milk fatty acids, and milk sn-2 fatty acids in goat’s milk. Firstly, we could see that the fat content increased in low microalgae supplementation goat’s milk (LM, 15 g/day) and the lactose content decreased in medium microalgae supplementation goat’s milk (MM, 25 g/day) compared with control goat’s milk (C, 0 g/day). Moreover, the absolute concentration of the docosahexaenoic acid (DHA) of LM, MM, and high microalgae supplementation (HM, 35 g/day) goat’s milk was 29.485, 32.351, and 24.817 mg/100 g raw milk, respectively, which were all higher than that in the control goat’s milk with 4.668 mg/100 g raw milk. In addition, the sn-2 DHA content increased in MM and HM goat’s milk. However, the decreasing trend of the sn-2 DHA content was observed in LM goat’s milk. As for other fatty acids, the oleic acid (C18:1n9c) and linolenic acid (C18:3n3) content decreased and increased, respectively, in all experimental goat milk. Finally, an interesting phenomenon was found, which was that docosanoic acid (C22:0) and tetracosenic acid (C24:1) were only detected in test goat’s milk. Consequently, the phenomena of this study demonstrated that dietary Schizochytrium microalgae have an obvious effect on the fatty acid and sn-2 fatty acid profile of goat’s milk, and they provide an effective method to improve the content of goat’s milk DHA in practical production.

Enrichment of Ewe’s Milk with Dietary n-3 Fatty Acids from Palm, Linseed and Algae Oils in Isoenergetic Rations

Increasing the levels of n-3 fatty acids (FA) in dairy products is an important goal in terms of enhancing the nutritional value of these foods for the consumer. The purpose of this research was to evaluate the effects of linseed and algae oil supplements in ovine isoenergetic diets on healthy milk fatty acid composition, mainly n-3. Seventy-two Churra dairy ewes were divided and randomly assigned to four experimental treatments for 6 weeks. The treatments consisted of a TMR (40:60 forage:concentrate ratio) that varied according to the inclusion of different types of fat (23 g/100 g TMR): hydrogenated palm oil (control), linseed oil (LO), calcium soap of linseed oil (CaS-LO) and marine algae oil (AO). The most effective lipid supplement to increase n-3 FA in milk was AO. 22:6 n-3 and total n-3 PUFA content increased from 0.02 and 0.60% (control) to 2.63 and 3.53% (AO), respectively. All diets supplemented with n-3 FA diminished the content of saturated FA in milk and its atherogenic index, while the levels of trans-11 18:1 and cis-9 trans-11 18:2 significantly increased. Overall, the enhancement of n-3 FA in ewe’s milk would be advantageous for the manufacture of nutritionally improved cheeses.

Dietary strategies to enrich milk with healthy fatty acids – a review

Feed is the main factor impacting the composition and quality of milk of dairy animals. Therefore, the present review explores the effects of feed and nutrition on milk fat content and levels of healthy fatty acids (FA) in milk consumed by humans. Milk and dairy products are two main sources of healthy and unhealthy FA in human nutrition. The concentrations of FA in milk depend mainly on diets; therefore, milk FA concentrations and ratios can be greatly altered by some feeding strategies. Dietary supplementation of the diets of dairy livestock with vegetable seeds or oils, microalgae and phytogenic feed additives, and feeding of some grasses can enhance the contents of healthy FA, including n-3 FA, α-linolenic acid, conjugated linoleic acid (CLA) and, generally, unsaturated FA in milk and dairy products. Enrichment of milk with healthy FA may make milk a source of anticarcenogens (CLA and polyphenols) for human health. This review, therefore, focusses on the current research findings on enrichment of milk with healthy FA and summarizes some effective supplementation strategies to alter milk FA profile.

A Brief Journey into the History of and Future Sources and Uses of Fatty Acids

Fats and lipids have always had a primary role in the history of humankind, from ancient civilisations to the modern and contemporary time, going from domestic and cosmetic uses, to the first medical applications and later to the large-scale industrial uses for food, pharmaceutical, cosmetics, and biofuel production. Sources and uses of those have changed during time following the development of chemical sciences and industrial technological advances. Plants, fish, and animal fats have represented the primary source of lipids and fats for century. Nowadays, the use of fatty acid sources has taken a turn: industries are mainly interested in polyunsaturated fatty acids (PUFAs), which have beneficial properties in human health; and also, for high-value fatty acids product for innovative and green production of biofuel and feedstocks. Thus, the constant increase in demand of fatty acids, the fact that marine and vegetable sources are not adequate to meet the high level of fatty acids required worldwide and climate change, have determined the necessity of the search for renewable and sustainable sources for fatty acids. Biotechnological advances and bioengineering have started looking at the genetic modification of algae, bacteria, yeasts, seeds, and plants to develop cell factory able to produce high value fatty acid products in a renewable and sustainable manner. This innovative approach applied to FA industry is a peculiar example of how biotechnology can serve as a powerful mean to drive the production of high value fatty acid derivatives on the concept of circular bioeconomy, based on the reutilisation of organic resources for alternative and sustainable productive patterns that are environmentally friendly.

Alternative and Unconventional Feeds in Dairy Diets and Their Effect on Fatty Acid Profile and Health Properties of Milk Fat

Simple Summary

Milk fat is an important compound in human nutrition. From a nutritional point of view, the production of milk with a higher content of polyunsaturated fatty acids, especially of those from the n3 group, is desirable because consumption of a diet with a lower n6/n3 ratio is considered to be beneficial for humans. The most effective way to achieve this goal is via dietary manipulations in ruminants. In addition to the feedstuffs commonly used in dairy animal nutrition, there are some alternative or unconventional feedstuffs that are often used for other purposes, e.g., for the reduction of methane production in the rumen. However, such feedstuffs can also alter the fatty acid profile of milk, and thus they can have an impact on the health properties of milk fat.

Abstract

Milk fat is an important nutritional compound in the human diet. From the health point of view, some fatty acids (FAs), particularly long-chain PUFAs such as EPA and DHA, have been at the forefront of interest due to their antibacterial, antiviral, anti-inflammatory, and anti-tumor properties, which play a positive role in the prevention of cardiovascular diseases (CVD), as well as linoleic and γ-linolenic acids, which play an important role in CVD treatment as essential components of phospholipids in the mitochondria of cell membranes. Thus, the modification of the FA profile—especially an increase in the concentration of polyunsaturated FAs and n-3 FAs in bovine milk fat—is desirable. The most effective way to achieve this goal is via dietary manipulations. The effects of various strategies in dairy nutrition have been thoroughly investigated; however, there are some alternative or unconventional feedstuffs that are often used for purposes other than basic feeding or modifying the fatty acid profiles of milk, such as tanniferous plants, herbs and spices, and algae. The use of these foods in dairy diets and their effects on milk fatty acid profile are reviewed in this article. The contents of selected individual FAs (atherogenic, rumenic, linoleic, α-linolenic, eicosapentaenoic, and docosahexaenoic acids) and their combinations; the contents of n3 and n6 FAs; n6/n3 ratios; and atherogenic, health-promoting and S/P indices were used as criteria for assessing the effect of these feeds on the health properties of milk fat.

Effects of Inclusion of Schizochytrium spp. and Forage-to-Concentrate Ratios on Goats' Milk Quality and Oxidative Status

Although the dietary inclusion level of polyunsaturated fatty acids (PUFA) and the forage: concentrate (F:C) ratio affect milk quality, their interaction has not been broadly studied. To address such gaps and limitations a two-phase trial using twenty-two dairy goats was carried out. During the first phase, both groups (20 HF n = 11; high forage and 20 HG n = 11; high grain) were supplemented with 20 g Schizochytrium spp./goat/day. The 20 HF group consumed a diet with F:C ratio 60:40 and the 20 HG-diet consisted of F:C = 40:60. In the second phase, the supplementation level of Schizochytrium spp. was increased to 40 g/day/goat while the F:C ratio between the two groups were remained identical (40 HF n = 11; high forage and 40 HG n = 11; high grain). Neither the Schizochytrium spp. supplementation levels (20 vs. 40) nor the F:C ratio (60:40 vs. 40:60) affected milk performance. The high microalgae level (40 g) in combination with high grain diet (40 HG) modified the proportions of docosahexaenoic acid (DHA), docosapentaenoic acid (DPA), and conjugated linoleic acid (CLA) and the ω3/ω6 ratio in milk, to a beneficial manner according to human health recommendation guidelines. However, the highest inclusion level of Schizochytrium spp. (40 g) and foremost in combination with the high grain diets (40 HG) induced an oxidative response as observed by the increased protein carbonyls (CP) and malondialdehyde (MDA) levels in milk and blood plasma indicating severe limitations for a long-term, on-farm application. In conclusion, the supplementation with 20 g Schizochytrium spp. and high forage diet (60:40) appears to be an ideal formula to enrich dairy products with essential biomolecules for human health without adversely affect milk oxidative stability.

Effect of Marine Algae Supplementation on Somatic Cell Count, Prevalence of Udder Pathogens, and Fatty Acid Profile of Dairy Goats' Milk

The aim of this study was to evaluate the effect of the Schizochytrium limacinum marine algae on the milk composition and fatty acid profile, somatic cell count, and prevalence of pathogen bacteria in the raw milk of multiparous Alpine goats. Twenty-eight dairy goats were randomly allocated to two groups: control group (C)-fed with 1500 g alfalfa hay and 600 g concentrate; experimental group (MA)-received the same forages and concentrate supplemented with 10 g/head/day marine algae. The goats were housed indoors, while the experiment lasted five weeks, and the milk samples were taken every week. Marine algae feeding had no negative effect on milk composition. The marine algae inclusion significantly decreased the milk somatic cell count and the presence of udder pathogens in the MA group. Mean somatic cell count and presence of udder pathogens were 5.73 log cells/mL and 31%, respectively, in the C group, while these values were 5.34 log cells/mL and 10%, respectively, in the MA group. The marine algae supplementation significantly increased DHA and rumenic acid concentration in the milk of the MA group (0.32 and 0.99 g/100 g of fatty acids, respectively) compared to the C group (0.04 and 0.65 g/100 g of fatty acids, respectively). It can be concluded that a diet supplemented with marine algae significantly improves the udder health of goats and the concentrations of health-promoting fatty acids in milk.

Effect of Dietary Hazelnut Peels on the Contents of Fatty Acids, Cholesterol, Tocopherols, and on the Shelf-Life of Ripened Ewe Cheese

Hazelnut peel (HNP), a by-product from the chocolate industry, is considered to be a suitable ingredient to be included in the diet of ruminants. This study aimed to evaluate the effect of feeding dairy ewes with a diet containing HNP on ripened cheese quality, including fatty acid (FA) profile, cholesterol, and tocopherol content, as well as stability during storage under commercial conditions. In total, 10 experimental cheeses were produced with bulk milk obtained from ewes fed a commercial concentrate (C group; n = 5) or a concentrate containing 36% HNP in dry matter (HNP group; n = 5). After 40 days of aging, each cheese was sub-sampled into three slices: one was analyzed immediately (C0 and HNP0), and the other two were refrigerated and analyzed after seven days (C7 and HNP7) and 14 days (C14 and HNP14), respectively. Compared to C, HNP cheese had more than twice as many tocopherols and mono-unsaturated FA and respectively 38% and 24% less of cholesterol and saturated FA. Tocopherols and cholesterol levels remained rather stable up to 14 days of storage regardless of the experimental group, suggesting no cholesterol oxidation. Therefore, the inclusion of HNP in ewe diets could be a valid resource to produce cheese with a healthier lipid profile and higher tocopherols content.

Rumen biohydrogenation and milk fatty acid profile in dairy ewes divergent for feed efficiency

A sustainable increase in livestock production would require selection for improved feed efficiency, but the mechanisms underlying this trait and explaining its large individual variation in dairy ruminants remain unclear. This study was conducted in lactating ewes to test the hypothesis that rumen biohydrogenation (BH) would differ between high- and low-efficiency animals, and these differences would be reflected in rumen fatty acid (FA) profile and affect milk FA composition. A second aim was to identify differences in FA that may serve as biomarkers of feed efficiency. Data of daily feed intake and milk yield and composition, as well as body weight, were collected individually over a 3-wk period in 40 ewes. The difference between the mean actual and predicted feed intake (estimated through metabolizable energy requirements for maintenance, production, and body weight change) over the period was used as the feed efficiency index (FEI) to select 8 of the highest feed efficiency (H-FE) and 8 of the lowest feed efficiency (L-FE) animals. In addition, residual feed intake (RFI) was estimated as the residual term from the regression of feed intake on various energy sinks. Rumen and milk FA composition were characterized by using gas chromatography, and results were analyzed using a statistical model that included the fixed effect of the group (H-FE vs. L-FE). The FEI averaged -0.29 ± 0.046 and 0.81 ± 0.084 in H-FE and L-FE, respectively, whereas RFI averaged -0.16 ± 0.084 and 0.18 ± 0.082, respectively. The correlation coefficient between both metrics was 0.69. Feed intake was similar in both groups, but H-FE showed greater milk yield, with increases in lactose content and yield, and in milk protein and fat production. Results from rumen FA profiles included a lower proportion of 18:2n-6, cis-9 18:1, and of several of their BH metabolites, and a greater concentration of 18:0, which may indicate that the apparent BH would be more complete in more efficient sheep. Milk FA analysis suggested that the greater fat yield in the H-FE group was mostly explained by increased de novo FA synthesis, whereas their milk would have lower proportions of cis-9 18:1 and C20 to 22n-6 polyunsaturated FA than L-FE. Stepwise multiple linear regression suggested that milk C20 to 22n-6 PUFA might be convenient biomarkers to discriminate more efficient dairy sheep. Further research is needed to validate these findings (e.g., under different dietary conditions).

Sheep and Goats Respond Differently to Feeding Strategies Directed to Improve the Fatty Acid Profile of Milk Fat

Simple Summary

Sheep and goat milk, as well as dairy products, are considered good sources of high-quality nutrients, particularly proteins and fats. Many positive effects on human health have been attributed to the consumption of dairy containing specific fatty acids, including some compounds originating from the polyunsaturated FA (PUFA) biohydrogenation operated by rumen microbes. In this bibliographic review, several nutritional strategies able to improve the milk fatty acids (FA) profile, in terms of an increase in the concentration of fatty acids considered beneficial to human health, are presented and discussed, with special attention to the differences between the two species.

Abstract

This bibliographic review presents and discusses the nutritional strategies able to increase the concentration of beneficial fatty acids (FA) in sheep and goat milk, and dairy products, with a particular focus on the polyunsaturated FA (PUFA), and highlights differences between the two species. In fact, by adopting appropriate feeding strategies, it is possible to markedly vary the concentration of fat in milk and improve its FA composition. These strategies are based mostly on the utilization of herbage rich in PUFA, or on the inclusion of vegetable, marine, or essential oils in the diet of lactating animals. Sheep respond more effectively than goats to the utilization of fresh herbage and to nutritional approaches that improve the milk concentration of c9,t11-conjugated linoleic acid (c9,t11-CLA) and α-linolenic acid. Dietary polyphenols can influence milk FA profile, reducing or inhibiting the activity and growth of some strains of rumen microbes involved in the biohydrogenation of PUFA. Although the effectiveness of plant secondary compounds in improving milk FA composition is still controversial, an overall positive effect has been observed on the concentration of PUFA and RA, without marked differences between sheep and goats. On the other hand, the positive effect of dietary polyphenols on the oxidative stability of milk fat appears to be more consistent.

Study on Schizochytrium sp. improving the growth performance and non-specific immunity of golden pompano (Trachinotus ovatus) while not affecting the antioxidant capacity

A feeding experiment was conducted to determine the effects of Schizochytrium sp. on growth performance, antioxidant capacity and non-specific immunity in golden pompano (Trachinotus ovatus).Two diets were formulated with or without Schizochytrium sp. supplemented (D1:0% and D2: 3%) to feed fish for 8 weeks. Results showed that growth performance, feed intake and survival rate increased significantly with Schizochytrium sp. supplemented (P < 0.05). Feed coefficient rate (FCR) of golden pompano fed the diet supplemented with Schizochytrium sp. was significantly lower than that of fish fed the control diet (P < 0.05). No significant differences were found in antioxidant capacity both in transcriptional level, including nclear factor erythroid-2-related factor-2 (Nrf2), Kelch-like-ECH-associated protein (keap1), catalase (CAT), glutathione peroxidase (GSH-PX) and heme oxygenase 1 (HO-1) and enzyme activity, such as total antioxidant capacity (T-AOC), malondialdehyde (MDA) and superoxide dismutase (SOD) (P > 0.05). Gut amylase and lipase were significantly higher in dietary Schizochytrium sp. supplemented treatment than that in control group (P < 0.05). The relative peroxisome proliferator-activated receptor-α (PPARα) expression level in liver was significantly higher in Schizochytrium sp supplemented treatment than that in control one (P < 0.05). The mRNA expression of myeloid differentiation factor 88 (MyD88), IL-1R-associated kinases 4 (IRAK4), interferon regulating Factor 3 (IRF3), interferon regulating Factor 3(IRF7) and heat shock protein 70 (HSP70) were significantly lower in Schizochytrium sp. supplemented treatment than that in control one (P < 0.05). In Schizochytrium sp. supplemented diet, golden pompano had significantly longer villi length than that in control diet (P < 0.05); muscle thickness in Schizochytrium sp. supplemented diet was thicker than that in control one (P < 0.05) and there were more goblet cells in Schizochytrium sp. treatment (P < 0.05). After the rearing trial, an air exposure trial was conducted. Results showed that the air-exposure mortality (AEM) and mRNA expression level of Nrf2, keap1, CAT, GSH-PX and HO-1 showed no significant difference (P > 0.05). These results indicated that dietary Schizochytrium sp. improved the growth performance and non-specific immunity of golden pompano while made no difference to antioxidant capacity.

Increasing dietary levels of docosahexaenoic acid-rich microalgae: Ruminal fermentation, animal performance, and milk fatty acid profile of mid-lactating dairy cows

This study aimed to evaluate the effects of increasing dietary levels of microalgae (ALG), rich in docosahexaenoic acid (DHA; All-G-Rich, Alltech, Nicholasville, KY), in isolipidic diets, on animal performance, nutrient digestibility, ruminal fermentation, milk fatty acid profile, energy balance, microbial protein synthesis, and blood serum metabolites in mid-lactating dairy cows. Twenty-four Holstein cows [130.3 ± 15.4 d in milk, and 30.8 ± 0.543 kg/d of milk yield (mean ± standard error)] were used in a 4 × 4 Latin square design experiment to evaluate the following treatments: control diet, without addition of ALG; and increasing levels of ALG [2, 4, and 6 g/kg of dry matter (DM)]. The ALG decreased DM intake and increased total-tract DM apparent digestibility. A tendency was observed for a quadratic effect on total-tract NDF digestibility by ALG inclusion, with peak value of the quadratic response at 4.13 g/kg of DM dose. Moreover, ALG increased ruminal pH and decreased acetate and total volatile fatty acid concentrations. Fat-corrected milk and energy-corrected milk were quadratically affected, and a tendency for a milk yield effect was observed when ALG levels increased, whereas maximal yields were observed with intermediate doses. Milk fat, protein, and lactose concentrations were diminished, whereas productive efficiency was improved by the increase of ALG levels. Saturated fatty acid proportions were decreased, whereas polyunsaturated fatty acid proportions were increased when ALG was fed. There was low DHA transfer into milk; however, ALG inclusion decreased C18:0, C18:1 cis-9, C18:2 cis-9,12, and C18:3 cis-9,12,15 proportions, and increased C18:2 cis-9,trans-11, C18:1 trans-9, and C18:1 trans-11 proportions. Gross energy intake was decreased, whereas no effect was observed on digestible, metabolizable, or net energy intake. The ALG inclusion quadratically affected the microbial protein synthesis, with maximal enhancement at 3.24 g/kg of DM dose, and also increased serum cholesterol concentration. Under the conditions of this experiment, the inclusion of ALG in diets for mid-lactating dairy cows decreased feed intake and increased nutrient digestibility, improving productive efficiency and modifying milk fatty acid profile. Estimated intermediate doses (1.22 to 2.90 g/kg of DM) of DHA-rich ALG may be beneficial to milk, fat-corrected milk, and energy-corrected milk yields, and is recommended for dairy cows.

Enhancing Omega-3 Long-Chain Polyunsaturated Fatty Acid Content of Dairy-Derived Foods for Human Consumption

Omega-3 polyunsaturated fatty acids (n-3 PUFA) are termed essential fatty acids because they cannot be synthesized de novo by humans due to the lack of delta-12 and delta-15 desaturase enzymes and must therefore be acquired from the diet. n-3 PUFA include α-linolenic acid (ALA, 18:3n-3), eicosapentaenoic (EPA, 20:5n-3), docosahexaenoic (DHA, 22:6n-3), and the less recognized docosapentaenoic acid (DPA, 22:5n-3). The three long-chain (≥C20) n-3 PUFA (n-3 LC-PUFA), EPA, DHA, and DPA play an important role in human health by reducing the risk of chronic diseases. Up to the present time, seafood, and in particular, fish oil-derived products, have been the richest sources of n-3 LC-PUFA. The human diet generally contains insufficient amounts of these essential FA due largely to the low consumption of seafood. This issue provides opportunities to enrich the content of n-3 PUFA in other common food groups. Milk and milk products have traditionally been a major component of human diets, but are also among some of the poorest sources of n-3 PUFA. Consideration of the high consumption of milk and its processed products worldwide and the human health benefits has led to a large number of studies targeting the enhancement of n-3 PUFA content in dairy products. The main objective of this review was to evaluate the major strategies that have been employed to enhance n-3 PUFA content in dairy products and to unravel potential knowledge gaps for further research on this topic. Nutritional manipulation to date has been the main approach for altering milk fatty acids (FA) in ruminants. However, the main challenge is ruminal biohydrogenation in which dietary PUFA are hydrogenated into monounsaturated FA and/or ultimately, saturated FA, due to rumen microbial activities. The inclusion of oil seed and vegetable oil in dairy animal diets significantly elevates ALA content, while the addition of rumen-protected marine-derived supplements is the most effective way to increase the concentration of EPA, DHA, and DPA in dairy products. In our view, the mechanisms of n-3 LC-PUFA biosynthesis pathway from ALA and the biohydrogenation of individual n-3 LC-PUFA in ruminants need to be better elucidated. Identified knowledge gaps regarding the activities of candidate genes regulating the concentrations of n-3 PUFA and the responses of ruminants to specific lipid supplementation regimes are also critical to a greater understanding of nutrition-genetics interactions driving lipid metabolism.

Monoraphidium sp. HDMA-20 is a new potential source of α-linolenic acid and eicosatetraenoic acid

BACKGROUND

ω-3 polyunsaturated fatty acids (PUFAs) are synthesized from α-Linolenic acid (ALA, C18:3ω3) and play important roles in anti-inflammatory and antioxidant responses in mammal cells. ALA is an essential fatty acid which cannot be produced within the human body and must be acquired through diet. The purpose of this study was to evaluate the potential of a novel microalgal strain (HDMA-20) as a source of ω-3 PUFAs including ALA and eicosatetraenoic acid (ETA, C20:4ω3).

METHOD

Phylogenetic Neighbor-Joining analysis based on 18S ribosomal DNA sequence was used to identify the microalga strain HDMA-20. Autotrophic condition was chosen to cultivate HDMA-20 to reduce the cultivation cost. GC-MS was used to determine the fatty acid composition of HDMA-20 lipid.

RESULTS

A microalgal strain (HDMA-20) from Lake Chengfeng (Daqing, Heilongjiang province, China) was found to accumulate high content of ω-3 PUFAs (63.4% of total lipid), with ALA and eicosatetraenoic acid (ETA, C20:4ω3) accounting for 35.4 and 9.6% of total lipid, respectively. Phylogenetic analysis based on 18S ribosomal DNA sequences suggested that the HDMA-20 belonged to genus Monoraphidium (Selenastraceae, Sphaeropleales) and its 18S rDNA sequence information turned out to be new molecular record of Monoraphidium species. The biomass productivity and lipid content of HDMA-20 were also investigated under autotrophic condition. The biomass productivity of HDMA-20 reached 36.3 mg L^- 1 day^- 1, and the lipid contents was 22.6% of dry weight.

CONCLUSION

HDMA-20 not only represent an additional source of ALA, but also a totally new source of ETA. The high content of ω-3 PUFAs, especially ALA, of HDMA-20, makes it suitable as a source of nutrition supplements for human health. In addition, HDMA-20 exhibited good properties in growth and lipid accumulation, implying its potential for cost-effective ω-3 PUFAs production in future.

Enhancement of dairy sheep cheese eating quality with increased n-3 long-chain polyunsaturated fatty acids

This study investigated the effect of different plant oil-infused and rumen-protected wheat-based pellets containing eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) on n-3 long-chain (≥C₂₀) polyunsaturated fatty acid (LC-PUFA) content, fatty acid recovery, and sensory attributes of ripened cheese from dairy sheep. During a 10-wk supplementary feeding trial, 60 dairy ewes balanced by live weight, milk yield, parity, and sire breed were randomly divided into 6 groups that were (1) supplemented with on-farm existing commercial wheat-based pellets without oil inclusion (control) or supplemented with wheat-based pellets infused with 50 mL/kg dry matter of oils from (2) canola, (3) rice bran, (4) flaxseed, (5) safflower, and (6) rumen-protected EPA + DHA. Milk samples from each treatment were collected separately by sire breed during the experimental period for cheese processing at the end of the experiment. Twelve batches of cheese (2 batches per treatment) were processed and ripened for 120 d. Three cheese samples were collected and analyzed for each cheese making session (total of 36 cheese samples) at d 120 of ripening. Processed cheese of rumen-protected EPA + DHA had the most efficiency at elevating total n-3 LC-PUFA [total EPA + DHA + docosapentaenoic acid (DPA, 22:5n-3] content compared with the control (0.49 vs. 0.28%). Flaxseed elicited the greatest enhancement of α-linolenic acid (ALA, 18:3n-3), whereas safflower was the most effective diet in enhancing the level of linoleic acid (18:2n-6) in cheese (1.29 vs. 0.71% and 4.8 vs. 3.3%, respectively). Parallel recoveries of n-3 and n-6 LC-PUFA were observed across all treatments except for α-linolenic acid and EPA. Cheese eating sensory traits were also highly affected by oil supplementation, with the highest score of 7.5 in cheese from the rice bran and flaxseed treatments. These results provide new insights into the biological mechanisms and processes that determine dairy ewe milk productivity by underpinning the vital biological role of n-3 LC-PUFA in not only enhancing the healthy composition of cheese from ewes but also translating it into consumer acceptability.

In vitro response to EPA, DPA, and DHA: Comparison of effects on ruminal fermentation and biohydrogenation of 18-carbon fatty acids in cows and ewes

The modulation of milk fat nutritional quality through fish oil supplementation seems to be largely explained by the action of n-3 very long chain polyunsaturated fatty acids (PUFA) on ruminal biohydrogenation (BH) of C18 fatty acids (FA). However, relationships among this action, disappearance of those PUFA in the rumen, and potential detrimental consequences on ruminal fermentation remain uncertain. This study compared the effect of 20:5n-3 (eicosapentaenoic acid; EPA), 22:5n-3 (docosapentaenoic acid; DPA), and 22:6n-3 (docosahexaenoic acid; DHA) on rumen fermentation and BH of C18 FA and was conducted simultaneously in cows and sheep to provide novel insights into interspecies differences. The trial was performed in vitro using batch cultures of rumen microorganisms with inocula collected from cannulated cows and ewes. The PUFA were added at a dose of 2% incubated dry matter, and treatment effects on ruminal C18 FA concentrations, PUFA disappearances, and fermentation parameters (gas production, ammonia and volatile FA concentrations, and dry matter and neutral detergent fiber disappearances) were examined after 24 h of incubation. A principal component analysis suggested that responses to PUFA treatments explained most of the variability; those of ruminant species were of lower relevance. Overall, EPA and DHA were equally effective for inhibiting the saturation of trans-11 18:1 to 18:0 and had a similar influence on ruminal fermentation in cows and sheep (e.g., reductions in gas production and acetate:propionate ratio). Nevertheless, DHA further promoted alternative BH pathways that lead to trans-10 18:1 accumulation, and EPA seemed to have specific effects on 18:3n-3 metabolism. Only minor variations attributable to DPA were observed in the studied parameters, suggesting a low contribution of this FA to the action of marine lipids. Although most changes due to the added PUFA were comparable in bovine and ovine, there were also relevant specificities, such as a stronger inhibition of 18:0 formation in cows and a greater increase in 18:3n-3 metabolites in sheep. No direct relationship between in vitro disappearance of the incubated PUFA and effect on BH (in particular, inhibition of the last step) was found in either cows or ewes, calling into question a putative link between extent of disappearance and toxicity for microbiota. Conversely, an association between the influence of these PUFA on ruminal lipid metabolism and fermentation may exist in both species. In vivo verification of these findings would be advisable.

mRNA abundance of genes involved in mammary lipogenesis during fish oil- or trans-10,cis-12 CLA-induced milk fat depression in dairy ewes

Milk fat depression (MFD) caused by trans-10,cis-12 18:2 is known to be mediated in cows and ewes by downregulation of mammary lipogenic genes. However, transcriptional mechanisms underlying marine lipid-induced MFD have not been well defined yet and the few available studies in ovine are not consistent. This trial was conducted to directly compare changes in animal performance, milk fatty acid composition, and particularly mammary mRNA abundance of candidate lipogenic genes and transcription factors in response to the inclusion of fish oil or trans-10,cis-12 18:2 in the dairy sheep diet. To meet this objective, 12 lactating Assaf ewes (on average, 64 days in milk, producing 1.72 kg of milk/d with 5.17% of fat) were divided into 3 groups and offered a total mixed ration without supplementation (control) or supplemented with 2.4% dry matter of fish oil (FO treatment) or 1% dry matter of a commercial product rich in trans-10,cis-12 18:2 (CLA treatment) for 39 d. Measurements and samplings were conducted before starting the treatments and at the end of the trial. Milk samples were used for RNA extraction from somatic cells. Feed intake was not affected by lipid supplements, and as designed, reductions in milk fat concentration (-31%) were similar in the 2 treatments, although the unpredicted increase in milk production with FO counteracted the anticipated reduction in milk fat yield. Nevertheless, this did not preclude the detection of FO-induced decreases in the mRNA abundance of candidate lipogenic genes [e.g., acyl-CoA synthetase short-chain family member 2 (ACSS2), fatty acid synthase (FASN), and lipin 1 (LPIN1)], thus supporting the hypothesis that transcriptional regulation would be a relevant component of this type of MFD in sheep. Expected CLA-induced downregulation of some genes, such as FASN or sterol regulatory element binding transcription factor 1 (SREBF1), could not be detected in our samples, which might be related, at least in part, to high inter-individual variation and relatively advanced lactation stage (on average 102-103 d in milk on d 38 and 39). Overall, direct comparison of the effects of dietary FO and CLA on transcript abundance of candidate lipogenic genes and transcription factors suggest that there might be relevant differences in the transcriptional control mechanisms underlying the MFD induced by each kind of supplement (i.e., fish oil or CLA).

Polyunsaturated fatty acid supplementation: effects of seaweed Ascophyllum nodosum and flaxseed on milk production and fatty acid profile of lactating ewes during summer

The research reported in this Research Communication was undertaken to evaluate the effects of different sources of polyunsaturated fatty acids (PUFA) supplemented in the diet on milk production and milk fatty acid profile of lactating ewes exposed to long term heat stress. The experiment was conducted during summer, involved 32 ewes divided into 4 groups of 8 each, and lasted 6 weeks. The ewes in all groups were fed twice daily and received 1·8 kg/d of oat hay and 1 kg/d of concentrate. Flaxseed group (FS) was supplemented with 250 g/d of whole flaxseed, Ascophyllum nodosum group (AG) was supplemented with 25 g/d of seaweed Ascophyllum nodosum, and the combination group (FS + AG) received both flaxseed and Ascophyllum nodosum supplementation. The control group (CON) was fed with 1 kg/d of pelleted concentrate without PUFA supplementation. Milk samples were collected twice daily per week, and analysed for fat, total protein, casein, and lactose content. At the beginning and then at 2, 4 and 6 week of the experiment each milk sample was analysed for milk fatty acids. Temperature-humidity index (THI) was calculated daily. Supplementation of flaxseed and of the combination of flaxseed and Ascophyllum nodosum increased milk yield. The total content of saturated fatty acids (SFA) in milk decreased for ewes fed FS, followed by FS + AG. On the contrary, monounsaturated fatty acids (MUFA) increased for ewes fed FS and FS + AG. The total n-3 FA was found higher in FS and FS + AG than in AG and CON groups mainly because of the increase in C 18 : 3 n-3 in FS and FS + AG milk. Milk from FS + AG resulted in the highest n-3/n-6 ratio and decreases in atherogenic and thrombogenic indices. The combination of seaweed Ascophyllum nodosum and flaxseed can be suggested as an adequate supplementation to sustain milk production and milk fatty acid profile of sheep during summer season.

Dose and time response of ruminally infused algae on rumen fermentation characteristics, biohydrogenation and Butyrivibrio group bacteria in goats

BACKGROUND

Micro-algae could inhibit the complete rumen BH of dietary 18-carbon unsaturated fatty acid (UFAs). This study aimed to examine dose and time responses of algae supplementation on rumen fermentation, biohydrogenation and Butyrivibrio group bacteria in goats.

METHODS

Six goats were used in a repeated 3 × 3 Latin square design, and offered a fixed diet. Algae were infused through rumen cannule with 0 (Control), 6.1 (L-Alg), or 18.3 g (H-Alg) per day. Rumen contents were sampled on d 0, 3, 7, 14 and 20.

RESULTS

H-Alg reduced total volatile fatty acid concentration and acetate molar proportion (P < 0.05), and increased propionate molar proportion (P < 0.05), whereas L-Alg had no effect on rumen fermentation. Changes in proportions of acetate and propionate in H-Alg were obvious from d 7 onwards and reached the largest differences with the control on d 14. Algae induced a dose-dependent decrease in 18:0 and increased trans-18:1 in the ruminal content (P < 0.05). H-Alg increased the concentrations of t9, t11-18:2 and t11, c15-18:2 (P < 0.05). L-Alg only seemed to induce a transient change in 18-carbon isomers, while H-Alg induced a rapid elevation, already obvious on d 3, concentrations of these fatty acid rose in some cases again on d 20. Algae had no effect on the abundances of Butyrivibrio spp. and Butyrivibrio proteoclasticus (P > 0.10), while H-Alg reduced the total bacteria abundance (P < 0.05). However, this was induced by a significant difference between control and H-Alg on d 14 (-4.43 %). Afterwards, both treatments did not differ as increased variation in the H-Alg repetitions, with in some cases a return of the bacterial abundance to the basal level (d 0).

CONCLUSIONS

Changes in rumen fermentation and 18-carbon UFAs metabolism in response to algae were related to the supplementation level, but there was no evidence of shift in ruminal biohydrogenation pathways towards t10-18:1. L-Alg mainly induced a transient effect on rumen biohydrogenation of 18-carbon UFAs, while H-Alg showed an acute inhibition and these effects were not associated with the known hydrogenating bacteria.

Effects of various dietary lipid additives on lamb performance, carcass characteristics, adipose tissue fatty acid composition, and wool characteristics

Tasco (Ascophyllum nodosum; TA) was compared to canola (CO), flax (FO), and safflower oils (SO) for effects on performance, carcass characteristics, and fatty acid profiles of adipose tissue in skirt muscle (SM), subcutaneous and perirenal adipose tissues, and wool production and quality characteristics of Canadian Arcott lambs. Fifty-six lambs were randomly assigned to dietary treatments (n = 14 per treatment). Diets consisted of a pelleted, barley-based finishing diet containing either TA, CO, FO, or SO (2% of dietary DM). Feed deliveries and orts were recorded daily. Lambs were weighed weekly and slaughtered once they reached ≥ 45 kg BW. Carcass characteristics, rumen pH, and liver weights were determined at slaughter. Wool yield was determined on mid-side patches of 100 cm2 shorn at d 0 and on the day before slaughter (d 105 or 140). Dye-bands were used to determine wool growth, micrometer and staple length. Adipose tissues and SM samples were taken at slaughter and analyzed for FA profiles. No effects were observed on intake, growth, or carcass characteristics. A greater (P = 0.02) staple strength of lambs fed CO was the only effect observed in wool. Flax oil increased total n-3 and decreased the n-6/n-3 ratio in tissue FA profiles (P < 0.001) in comparison to other diets. Tasco increased (P ≤ 0.001) SFA/PUFA in all tissues, whereas concentrations of CLA c-9, t-11 were greatest with SO in all tissues (P ≤ 0.02), compared to other diets. These results suggest Tasco supplementation did not improve the n-3/n-6 or SFA/PUFA ratios of lamb adipose tissues compared to other dietary lipid additives.

Dietary sunflower oil modulates milk fatty acid composition without major changes in adipose and mammary tissue fatty acid profile or related gene mRNA abundance in sheep

There are very few studies in ruminants characterizing mammary and adipose tissue (AT) expression of genes and gene networks for diets causing variations in milk fatty acid (FA) composition without altering milk fat secretion, and even less complementing this information with data on tissue FA profiles. This work was conducted in sheep in order to investigate the response of the mammary gland and the subcutaneous and perirenal AT, in terms of FA profile and mRNA abundance of genes involved in lipid metabolism, to a diet known to modify milk FA composition. Ten lactating Assaf ewes were randomly assigned to two treatments consisting of a total mixed ration based on alfalfa hay and a concentrate (60 : 40) supplemented with 0 (control diet) or 25 (SO diet) g of sunflower oil/kg of diet dry matter for 7 weeks. Milk composition, including FA profile, was analysed after 48 days on treatments. On day 49, the animals were euthanized and tissue samples were collected to analyse FA and mRNA abundance of 16 candidate genes. Feeding SO did not affect animal performance but modified milk FA composition. Major changes included decreases in the concentration of FA derived from de novo synthesis (e.g. 12:0, 14:0 and 16:0) and increases in that of long-chain FA (e.g. 18:0, c9-18:1, trans-18:1 isomers and c9,t11-CLA); however, they were not accompanied by significant variations in the mRNA abundance of the studied lipogenic genes (i.e. ACACA, FASN, LPL, CD36, FABP3, SCD1 and SCD5) and transcription factors (SREBF1 and PPARG), or in the constituent FA of mammary tissue. Regarding the FA composition of AT, the little influence of SO did not appear to be linked to changes in gene mRNA abundance (decreases of GPAM and SREBF1 in both tissues, and of PPARG in the subcutaneous depot). Similarly, the great variation between AT (higher contents of saturated FA and trans-18:1 isomers in the perirenal, and of cis-18:1, c9,t11-CLA and n-3 PUFA in the subcutaneous AT) could not be related to differences in gene mRNA abundance due to tissue site (higher LPL and CD36, and lower SREBF1 in perirenal than in subcutaneous AT). Overall, these results suggest a marginal contribution of gene expression to the nutritional regulation of lipid metabolism in these tissues, at least with the examined diets and after 7 weeks on treatments. It cannot be ruled out, however, that the response to SO is mediated by other genes or post-transcriptional mechanisms.