Effects of diet and physiological factors on milk fat synthesis, milk fat composition and lipolysis in the goat: A short review

Feed restriction affects milk performances and decreases milk lipolysis in dairy ewes

Spontaneous lipolysis results in the breakdown of milk fat by the lipoprotein lipase (EC: 3.1.1.34), an enzyme present in milk. Free fatty acids (FFAs) and by-products released in milk during lipolysis can alter both the organoleptic value of milk (off-flavors release) and technological properties of dairy products (decrease in creaming capabilities). Current climate change is having significant impacts on the feeding of grazing animals, with negative consequences on the availability and quality of grass. We and others have demonstrated that dietary restriction increases milk lipolysis in the cow species. However, no data about the impact of feed restriction on milk lipolysis is available in the ewe species. Thus, this paper aims to investigate the effect of feed restriction on milk characteristics with regard to lipolysis values in dairy ewes. Two groups of 24 multiparous Lacaune ewes in mid-lactation received a "non-restricted" control diet (100% of ad libitum DM intake) or a "restricted" (RESTR) diet (65% of ad libitum DM intake) according to a 2 × 2 crossover design. Milk gross composition together with lipolysis analyses were performed. Blood samples were also screened for metabolites or hormone concentrations. The RESTR treatment induced a decrease in milk production (- 21% compared with control treatment) and a modification of the metabolism of dairy ewes characterized by an increase in plasma non-esterified fatty acids (NEFAs), which represents the balance between adipose tissue mobilization and the use of NEFA by other tissues (+153%), cholesterol (+17%) and β-hydroxybutyrate (+4 %) levels. As a result, a decrease in BW of dairy ewes was observed (-7%). Feed restriction also resulted in a decrease in milk lipolysis estimated by the milk FFA measured by the copper-soap method (-63 and -62%, respectively, for morning and evening milking) or by the reference Bureau of Dairy Industry method (-51 and -57%, respectively, for morning and evening milking). The decrease in milk spontaneous lipolysis under feed restriction was not associated with a decrease in lipoprotein lipase activity in ewes. These results will be completed with proteomic and lipidomic studies in milk samples to better understand mechanisms initiated in the ewe species specifically with regard to lipolysis in milk.

Variations in Composition, Antioxidant Profile, and Physical Traits of Goat Milk within the Semi-Intensive Production System in Mountainous Areas during the Post-Weaning to End-of-Lactation Period

Dairy products from mountain-origin milk are known for their superior composition and quality. This study aimed to examine changes in composition, nutritional quality, and antioxidant properties of milk from semi-intensively managed goats in mountainous regions during the post-weaning to end-of-lactation period. Bulk tank milk samples from 10 farms were collected bi-weekly in the period from March to September. The farms were situated in regions with an average altitude of 772.20 m above sea level. The results revealed significant variations in milk composition, with fluctuations in fat, protein, lactose, and total solids. Milk yield per doe showed seasonal differences, with the highest yield in April and the lowest in September. Fatty acid composition exhibited changes throughout the sampling period, with variations in polyunsaturated fatty acids. Nutritional indices, such as the atherogenicity index and thrombogenicity index, remained within the recommended values. Antioxidant properties, including total phenolic content, DPPH, FRAP, and ABTS, showed significant differences, with higher values toward the end of the study. Milk pH, electrical conductivity, brix value, and refractive index also exhibited variations, while density and freezing point remained relatively stable. The study provided valuable information that can be used to develop breeding and feeding plans to achieve uniform milk quality in mountainous regions.

Impact of mixing coriander oil with goat feed on the chemical, microbiological and sensory characterizations of bio rayeb milk

This research aimed to investigate the properties of bio rayeb milk that results from goats fed on feed supplemented with different concentrations of coriander oil. The study design included a control treatment (C) and two coriander oil concentrations, a low level of (0.95%) T1 and a high level of (1.9%) T2. A probiotic starter culture, Direct Vat Set (DVS) of lactobacillus delbrueckii ssp. bulgaricus and streptococcus salivarius ssp. thermophilus in the ratio (1:1) was used to prepare bio rayeb. All treatments were stored at 4 °C for 2 weeks and analyzed on day one and at the end of storage. Results showed that the coagulation time during bio rayeb manufacturing remained consistent at almost 6 h for all batches. However, using a high coriander oil level (1.90%) significantly decreased the apparent viscosity and the content of monounsaturated fatty acids. The DPPH inhibition and the content of monounsaturated fatty acids increased. The electrophoresis chromatogram exhibited a high degree of proteolysis in T2 compared to the control and T1. Microbiologically, yeast, molds, and coliforms were absent in all treatments. Feeding goats on provender supplemented with a low concentration of coriander oil may positively impact the resultant milk's technological and sensorial properties.

Polymorphism at the CSN1S1 Locus and Energy Intake Level Affect Milk Traits and Casein Profiles in Rossa Mediterranea Goats

A total of twenty-seven Rossa Mediterranea lactating goats, consisting of nine homozygous for strong alleles (AA), twelve heterozygous (AF) and six homozygous for weak alleles (FF) at the CSN1S1 locus, were used to evaluate the effect of genotype, diet and genotype × diet interaction on goat milk traits and casein profile. The goats were used in a 3 × 3 factorial arrangement of treatments, with three genotypes (AA, AF and FF) and three different energy intake levels: high (H), medium (M) and low (L). The diets supplied a complete pelleted feed containing 65% of alfalfa hay, respectively, at 150%, 100% and 70% of the total energy requirements. Milk yield was significantly affected by the genotype and diet: Lower levels were found in FF goats than in AA and AF genotypes (673.7 vs. 934.5 and 879.8 d/g, respectively; p = 0.002) as well as in goats fed with the L diet (651.5 vs. 1041 and 852.9 g/d for H and M diet, respectively, p < 0.001). The genotype influenced the casein profile. Specifically, AA goat milk exhibited higher concentrations of total casein and α_s1-casein compared to AF and FF genotypes (for total casein and αs1-casein, respectively: 24.9 vs. 20.4 and 19.8 g/kg, p = 0.001; 7.2 vs. 3.7 and 0.7 g/kg, p < 0.001), while the FF genotype showed higher values for α_s2-casein concentrations compared to homozygous AA and heterozygous AF goats (3.1 vs. 2.4 and 2.5 g/kg, respectively, p < 0.001). A significant genotype x diet interaction occurred for αs2-casein levels (g/kg) (p = 0.034) and αs₁-casein yields (p = 0.027): The αs₂-casein level was not affected by the diet in AA goats, whereas it increased with energy intake in AF and FF genotypes. Conversely, the αs₁-casein yield gradually increased with energy intake in AA and AF groups, whereas the diet in FF goats did not modify it. The results demonstrated that high energy input, as well as the strong allele at the CSN1S1 locus, enhanced milk production and casein concentrations. Furthermore, they confirmed the existence of an interaction between α_s1-casein polymorphism and diets, influencing the milk casein composition and yield.

Associations between Somatic Cell Count and Milk Fatty Acid and Amino Acid Profile in Alpine and Saanen Goat Breeds

The main goal of this study was to evaluate the relation of different SCC levels in goat milk with goat milk yield, milk composition, FA, and AA profiles. Whereas the investigated herd was composed of Alpine and Saanen goats, the influence of breed on milk parameters and milk yield was also assessed. The research was carried out in 2022 at a Lithuanian dairy goat farm with 135 goats (Saanen = 66 and Alpine = 69) without evidence of clinical mastitis. The current research revealed a relationship between SCC with goat milk yield and composition. Goats with a high SCC had significantly lower milk yield (p < 0.001), lower content of lactose (p < 0.01), fat (p < 0.001) and higher protein content (p < 0.05) in their milk. The increase in most AA was significantly associated with increased SCC. The higher quantity of Asp, Glu, Ala, Met, His, Lys, Arg, EAA, NEAA, and TAA (compared with the low SCC group) (p < 0.05–0.01), Leu, Tyr, and BCAA (compared with the low and medium SCC group) were found in the milk of the high SCC group (p < 0.05–0.01). The distribution of the main FA groups was also related to SCC and showed a significant decrease in SCFA (p < 0.01–0.001) and an increase in LCFA, PUFA, and BCFA in the high SCC group (p < 0.05). All individual AA and their groups (EAA, NEAA, TAA, BCAA) were significantly lower in the milk of the Saanen goat breed (p < 0.001). The most individual FA ranged between goat breeds, while the total amount of SFA, UFA, and MUFA wasn’t affected by breed (p > 0.05). The research revealed a statistically significant relationship between SCC, AA, and FA, suggesting that these traits may be used as a biomarker in the goat selection process.

Milk yield and composition in dairy goats fed extruded flaxseed or a high-palmitic acid fat supplement

We compared the potential of dietary lipid supplements of different fatty acid compositions to affect milk performance when early lactation dairy goats were fed a high-concentrate diet. Thirty Alpine goats at 23 ± 5 d in milk were allocated to 1 of 10 blocks according to parity and milk fat concentration. Within each block, goats were randomly assigned to receive, during a period of 41 d, either CONT) a basal diet with a forage to concentrate ratio of 45:55, used as control, or PALM) the basal diet + 2% of a palmitic acid-enriched fat supplement, or FLAX) the basal diet + 7% of extruded flaxseed. Body weight, dry matter intake and milk yield were not different between treatments. As compared with CONT, goats fed PALM and FLAX had a greater milk fat concentration. Moreover, milk fat yield was numerically (but non-significantly) greater with PALM than with CONT. Milk fat from goats receiving PALM had a greater concentration of 16:0 as compared with CONT and FLAX, whereas a greater concentration of cis-9, cis-12, cis-15 18:3 was observed when goats were fed FLAX as compared with CONT and PALM. Under the conditions of the current experiment, dietary fat supplementation had only minor impacts on the yield of major milk constituents, with the exception of a modest increase in fat yield when goats were fed PALM. The impact of a greater concentration of 16:0 in milk fat of goats receiving this feed ingredient on the nutritive value of dairy products remains to be determined.

Feeding of palm oil fatty acids or rapeseed oil throughout lactation: Effects on mammary gene expression and milk production in Norwegian dairy goats

Lipid added as rapeseed or palm oil to the diet of dairy goats over 8 mo of one lactation alters fat secretion and milk fatty acid (FA) and protein composition. In this study, we examined the contribution of mammary gene expression to these changes and included 30 multiparous goats of Norwegian dairy goat breed for a 230-d experimental period, with indoor feeding from 1 to 120 d in milk (DIM), mountain grazing from 120 to 200 DIM, and indoor feeding from 200 to 230 DIM. After an initial period (1-60 DIM) when the control diet was given to all goats, the animals were subdivided into 3 groups of 10 goats. Treatments (60-230 DIM) were basal concentrate (control) alone or supplemented with either 8% (by weight) hydrogenated palm oil enriched with palmitic acid (POFA) or 8% (by weight) rapeseed oil (RSO). Milk was sampled individually from all animals throughout lactation, at 60, 120, 190, and 230 DIM for milk yield and composition. On d 60, 120, 190, and 230, mammary tissue was collected by biopsy to measure mRNA abundance of 19 key genes. None of the 19 genes involved in milk protein, apoptosis, lipid metabolism, transcription factors, and protein of the milk fat globule membrane, as measured by mRNA abundance, were affected by the lipid supplements, although POFA increased milk fat content, and POFA and RSO affected milk FA composition. Over the experimental period (120-230 DIM), the mRNA abundance of 13 of the 19 studied genes was affected by lactation stage. For some genes, expression either gradually increased from 120 to 230 DIM (CSN2,CASP8,CD36,GLUT4) or increased from 120 to 200 and then remained stable (XDH), or decreased (CSN3,G6PD,SREBF1,PPARG1) or increased only at 230 DIM (SCD1,SCD5,ELF3). For a second group of genes (CSN1, LALBA, FABP3, FASN, LPL, MFGE8), expression was stable over the lactation period. Our results suggest that factors other than gene expression, such as substrate availability or posttranscriptional regulation of these genes, could play an important role in the milk fat and FA responses to dietary fat composition in the goat. In conclusion, mammary gene expression in goats was more regulated by stage of lactation than by the dietary treatments applied.

Effects of Production Systems and Seasons on Retail-Goat-Milk Fatty-Acid Composition and Nutritional Indices in Greece

Simple Summary

The consumption of goat milk is constantly increasing. However, there are not many studies on the nutritional profile of retail goat milk. This study examined the effects of production systems (conventional and organic) and seasons (spring, summer, autumn and winter) on the fatty acid composition and nutritional indices related to the healthy fat consumption of fluid goat milk sold in the supermarkets. The production system did not significantly affect milk fatty-acid composition nor its nutritional value, whereas seasonal effects were observed. Overall, retail goat milk had a desirable nutritional value, irrespective of production system and season.

Abstract

An increased consumer interest in goat milk has been registered in recent years due to its health-related benefits. This study aimed to investigate the effects of production systems and seasons on fatty-acid composition and nutritional indices for the healthy fat consumption of retail goat milk. The study lasted one year, and milk samples (n = 160) from 14 brands (10 conventional and 4 organic) were collected on a monthly basis. Organic milk had a marginally lower fat and protein content compared with conventionally produced milk according to the declared chemical composition. The production system did not significantly affect milk fatty-acid composition and its nutritional value, indicating that there were no major differences in the feeding strategies between conventionally and organically raised ewes. Seasonal effects were observed in the fatty-acid profile and the nutritional indices. Lower content of saturated fatty acids (SFAs), hypocholesterolemic/hypercholesterolemic ratio (h/H) and linoleic acid/α-linolenic acid (LA/ALA) ratio values were observed in summer. Retail goat milk had a desirable nutritional value, irrespective of production system and season, due to the following characteristics: low atherogenic index (AI) and LA/ALA ratio values, and high h/H ratio, desirable fatty acid (DFA) values and health-promoting index values. In conclusion, neither production nor season significantly impacted the fatty-acid composition and the fat-consumption nutritional indices of retail goat milk produced in Greece.

The Effect of Coriander Oil Addition to Goat Feed on the Technological Properties of the Resultant Milk; Rayeb as a Product Model.. [DOI: 10.21203/rs.3.rs-1957228/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Goat milk is an essential alternative milk resource for those suffering from cow and buffalo milk allergies and is considered a nutrient protein source for children and neonates. This paper aims to answer the question: Does adding crude coriander oil to goats' food affect the quality of their milk and the properties of their products? Study the chemical, rheological, and microbiological properties and the acceptability of probiotic goat's rayeb milk. Two coriander oil concentrations were used in the study; a low level of 0.95% (T1) and a high level of 1.9% (T2). The results declared that coriander oil did not affect the coagulation time, which was almost six hours for all batches. At the same time, the apparent viscosity decreased significantly (p ≤ 0.05) in T2 with the high oil level. Moreover, treatments showed a significant (p ≤ 0.05) increase in the content of monounsaturated fatty acids and a decrease in polyunsaturated fatty acids. Low-level oil supplementation showed the best rayeb properties, surpassing the control treatment in most properties and higher sensory scores.

Goat Milk Foodomics. Dietary Supplementation of Sunflower Oil and Rapeseed Oil Modify Milk Amino Acid and Organic Acid Profiles in Dairy Goats

The dietary supplementation of vegetable oils is known to improve the dietary energy density as well as milk fatty acid profile; however, the impacts on the milk foodome is largely unknown. This study investigated the effect of two different sources of unsaturated fatty acids, rapeseed oil and sunflower oil, as a feeding supplement on the milk foodome from dairy goats. Nine Danish Landrace goats at 42 ± 5 days in milk were allocated to three treatment groups for 42 days with three animals per group. A control group received a basal diet made of forage and concentrate at an 85:15 ratio. On top of the basal diet, the second and third groups received rapeseed oil or sunflower oil supplements at 4% of dry matter, respectively. Goat milk was sampled on days 14, 21, and 42. The milk foodome was measured using gas chromatography–mass spectrometry and proton nuclear magnetic resonance spectroscopy. The milk levels of 2-hydroxyisovaleric acid, oxaloacetic acid, and taurine were higher in the milk from goats fed with sunflower oil compared to the control group. More glucose-1-phosphate was found in the milk from goats fed with rapeseed oil compared to the control group. Amino acids, valine and tyrosine, and 2-hydroxyisovaleric acid and oxaloacetic acid were higher in the sunflower group compared to the rapeseed group, while the milk from the rapeseed-fed goats had greater levels of ethanol and 2-oxoglutaric acid compared to the sunflower group. Thus, results show that foodomics is suitable for studying how milk chemistry changes as a function of feeding regime.

Expression patterns of major genes in fatty acid synthesis, inflammation, oxidative stress pathways from colostrum to milk in Damascus goats

The molecular regulation of milk secretion and quality in the transition period from colostrum to milk in goats is largely unknown. In the present study, mammary gland secretion of goats was collected in 0th, 4th, 7th, 14th and 28th days after parturition. In addition to composition and fatty acid profile of colostrum or milk, FASN, SCD, ACACA, COX-2, NRF2, TLR2, NF-kB, LTF and PTX3 genes expression patterns were determined from milk somatic cells. While somatic cell count (SCC), malondialdehyde (MDA), fat, fat-free dry matter, protein and lactose were highest as expression levels of the oxidative and inflammatory genes, freezing point and electrical conductivity were lowest in colostrum. With the continuation of lactation, most of the fatty acids, n3 ratio, and odour index increased but C14:0 and C16:0 decreased. While FASN was upregulated almost threefolds in 14th day, ACACA was upregulated more than fivefolds in 7th and 14th days. Separately, the major genes in fatty acid synthesis, inflammation and oxidative stress were significantly associated with each other due to being positively correlated. MDA was positively correlated with SCC and some of the genes related inflammation and oxidative stress. Furthermore, significant negative correlations were determined between SCC and fatty acid synthesis related genes. With this study, transition period of mammary secretion was particularly clarified at the molecular levels in Damascus goats.

Energy, nitrogen partitioning, and methane emissions in dairy goats differ when an isoenergetic and isoproteic diet contained orange leaves and rice straw crop residues

The aim of this study was to evaluate the effects of incorporating rice straw and orange leaves into the diets for goats. Ten Murciano-Granadina goats at mid lactation weighing 45 ± 0.3 kg were used in a crossover design. Two isoproteic and isoenergetic diets (180 g/kg DM and 17 MJ/kg DM, respectively) with alfalfa hay as forage source (33% of DM) were fed. A control diet (CON) incorporated barley as energy source and soy hulls as fiber component. The experimental diet (ORG) replaced barley and soy hulls with orange leaves (19% on DM basis), rice straw (12%, on DM basis) and soya oil (2%). Peas and horsebeans were the protein source in both diets. Each goat received the 2 treatments in 2 periods. Goats were fed the experimental diets and after 14 d on their respective treatments moved to individual metabolism cages for another 7 d. Subsequently, feed intake, total fecal and urine output and milk yield were recorded daily over the first 5 d. During the next 2 d ruminal fluid and blood samples were collected, and then individual gas-exchange measurements were recorded by a mobile open-circuit indirect calorimetry system using a head box. No differences in dry matter intake were detected, and apparent total-tract digestibility was greater in CON than ORG. Efficiency of metabolizable energy intake for milk and maintenance also was lower in response to ORG (0.65 vs. 0.63), with energy balance being negative (-12 kJ/kg of BW^0.75) due to mobilization of fat (-16 g/animal vs. 68 g/animal for ORG and CON, respectively). Although actual milk yield was lower in goats fed ORG (2.32 vs. 2.06 kg/d, respectively), energy-corrected milk did not differ (2.81 kg/d on average). In terms of milk quality, milk fat content, and concentrations of monounsaturated (18.54 vs. 11.55 g/100 g milk fat) and polyunsaturated fatty acids (5.75 vs. 3.99 g/100 g milk fat) were greater in goats fed ORG. Based on various indices, the milk produced by ORG would be less atherogenic and thrombogenic than CON milk. Compared with CON, enteric CH₄ emission was lower due to feeding ORG (reduction of 38 g CH₄/kg milk fat). Data suggest that greater fat mobilization in goats fed ORG might have been due to the apparent lack of synchrony between degradable protein and carbohydrate and the lipogenic nutrients associated with the lower cereal content of the ORG diet. Thus, goats fed ORG seemed to rely more on fat depots to help meet energy requirements and reach optimal performance. As such, the lower content of glucogenic nutrients in ORG did not favor body fat deposition and partitioning of ME into body tissue. Overall, responses in terms of CH₄ emissions and milk quality suggest that inclusion of rice straw and orange leaves in diets for small ruminants could be a valuable alternative to reuse, recycle and revalue agricultural by-products.

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.

Multivariate factor analysis of milk fatty acid composition in relation to the somatic cell count of single udder quarters

The present study investigated whether the fatty acid composition of milk changes in relation to an increase in the milk somatic cell count (SCC) of separate udder quarters. We investigated the potential of multivariate factor analysis to extract metabolic evidence from data on the quantity and quality of milk of quarters characterized by different SCC levels. We collected data from individual milk samples taken from single quarters of 49 Italian Holstein cows from the same dairy farm. Factor analysis was carried out on 64 individual fatty acids. In line with a previous study on multivariate factor analysis, a variable was considered to be associated with a specific factor if the absolute value of its correlation with the factor was ≥0.60. Seven factors were extracted that explained the following groups of fatty acids or functions: de novo synthesis, energy balance, uptake of dietary fatty acids, biohydrogenation, short-chain fatty acids, very long chain fatty acids, and odd- and branched-chain fatty acids. An ANOVA of factor scores highlighted the significant effects of the SCC level on de novo fatty acids and biohydrogenation. The de novo fatty acid factor decreased significantly with a high level of SCC, from just 10,000 cells/mL, whereas the biohydrogenation factor showed a significantly higher level in quarters with SCC levels greater than 400,000 cells/mL. This statistical approach enabled us to reduce the number of variables to a few latent factors with biological significance and to represent groups of fatty acids with a common origin and function. Multivariate factor analysis could therefore be key to studying the influence of SCC on the lipid metabolism of single quarters. This approach also demonstrated the metabolic differences between quarters of the same animal showing a different level of SCC.

High rumen degradable starch decreased goat milk fat via trans-10, cis-12 conjugated linoleic acid-mediated downregulation of lipogenesis genes, particularly, INSIG1

Background

Starch is an important substance that supplies energy to ruminants. To provide sufficient energy for high-yielding dairy ruminants, they are typically fed starch-enriched diets. However, starch-enriched diets have been proven to increase the risk of milk fat depression (MFD) in dairy cows. The starch present in ruminant diets could be divided into rumen-degradable starch (RDS) and rumen escaped starch (RES) according to their different degradation sites (rumen or intestine). Goats and cows have different sensitivities to MFD. Data regarding the potential roles of RDS in milk fat synthesis in the mammary tissue of dairy goats and in regulating the occurrence of MFD are limited.

Results

Eighteen Guanzhong dairy goats (day in milk = 185 ± 12 d) with similar parity, weight, and milk yield were selected and randomly assigned to one of three groups (n = 6), which were fed an LRDS diet (Low RDS = 20.52%), MRDS diet (Medium RDS = 22.15%), or HRDS diet (High RDS = 24.88%) for 5 weeks. Compared with that of the LRDS group, the milk fat contents in the MRDS and HRDS groups significantly decreased. The yields of short-, medium- and long-chain fatty acids decreased in the HRDS group. Furthermore, increased RDS significantly decreased ruminal B. fibrisolvens and Pseudobutyrivibrio abundances and increased the trans-10, cis-12 conjugated linoleic acid (CLA) and trans-10 C18:1 contents in the rumen fluid.

A multiomics study revealed that the HRDS diet affected mammary lipid metabolism down-regulation of ACSS2, MVD, AGPS, SCD5, FADS2, CERCAM, SC5D, HSD17B7, HSD17B12, ATM, TP53RK, GDF1 and LOC102177400. Remarkably, the significant decrease of INSIG1, whose expression was depressed by trans-10, cis-12 CLA, could reduce the activity of SREBP and, consequently, downregulate the downstream gene expression of SREBF1.

Conclusions

HRDS-induced goat MFD resulted from the downregulation of genes involved in lipogenesis, particularly, INSIG1. Specifically, even though the total starch content and the concentrate-to-fiber ratio were the same as those of the high-RDS diet, the low and medium RDS diets did not cause MFD in lactating goats.

Endocrine and metabolic status of commercial dairy goats during the transition period

The aim of this study was to evaluate temporal variations in circulating levels of selected hormones and metabolites in commercial dairy goats during the transition period. Blood samples from 940 goats were collected weekly, from -3 to 3 wk relative to delivery, to measure the effects of level of milk production, parity number, and litter size on concentrations of glucose, β-hydroxybutyrate (BHB), fatty acids, and plasma urea nitrogen (PUN). A subset of 80 goats [40 low-yielding (LY, < 1.8 L/d) and 40 high-yielding goats (HY, > 3.7 L/d)] were selected from the study population to measure the effects of level of milk production on plasma concentration of insulin, prolactin, and growth hormone. Average (±SD) milk yield (from 3 to 30 d in milk), body weight, and body condition score for the study population were 2.4 ± 0.78 L/d, 70 ± 16.0 kg, and 2.5 ± 0.28 units, respectively. Milk yield was moderately correlated with parity number (r = 0.49) but had weak correlation with litter size (r = 0.14). In multiparous but not in primiparous goats, antepartum concentrations of fatty acids and BHB increased with increasing litter size. Concentrations of fatty acids, BHB, and PUN were consistently lower in primiparous goats compared with those in second or greater parity. Postpartum, HY goats had higher ratios of glucose, fatty acids, and BHB to insulin than did LY goats, which might explain the greater mobilization of body tissues and enhanced milk production observed in this group. Collectively, our results indicate that increased milk yield has the most significant influence on the magnitude of body tissue mobilization. Our results also show that goats of higher parity display higher levels of lipid mobilization, and that both pregnancy and lactation are less able to elicit lipomobilization in primiparous compared with multiparous goats.

NMR Lipid Profile of Milk from Alpine Goats with Supplemented Hempseed and Linseed Diets

The supplementation of goat diets with natural products to obtain milk with nutraceutical components is a common practice. In these last years, the influence of supplementation of specifically designed diets has been studied with different analytical tools in order to explore possible beneficial effects in human consumption of animal milk and milk-derived products. In this study, the lipid fraction of milk from Alpine goats undergoing different dietary regimens was studied by ¹H-NMR spectroscopy. Alpine goats were fed with linseed or hempseed supplements, and after 14 weeks of treatment, milk was collected and analyzed. Results showed that feeding diets supplemented with seeds positively affected the fatty acid composition with a pronounced increase in unsaturated fatty acids for both diets compared to a control diet. Specifically, linolenic acid content was more than doubled for linseed diet compared with the hempseed and control groups, while linoleic acid greatly increased only upon hempseed supplementation. However, a number of conjugated linoleic acid (CLA) isomers and higher levels of fatty acids with trans configuration were found in supplemented diets, particularly in the linseed diet.

Evaluation of human breastmilk adulteration by combining Fourier transform infrared spectroscopy and partial least square modeling

A two-step chemometric procedure was developed on the attenuated total reflection-Fourier transform infrared data of human breastmilk to detect adulteration by water or cow milk. The samples, collected from a Milk Bank, were analyzed before and after adulteration with whole, skimmed, semi-skimmed cow milk and water. A preliminary clustering via principal component analysis distinguished three classes: pure milk, milk adulterated with water, and milk adulterated with cow milk. A first partial least square-discriminant analysis (PLS-DA) classification model was built and then applied on new samples to identify the specific adulterants. The external validation on this model reached 100% of the correct identification of pure milk and 90% of the type of adulterants. In the following step, four PLS calibration models were built to quantify the amount of the adulterant detected in the classification analysis. The prediction performance of these models on new samples showed satisfactory parameters with root mean square error of prediction and percentage relative error lower than 1.38% and 3.31%, respectively.

Quick changes of milk fatty acids after inclusion or suppression of linseed oil in the diet of goats

BACKGROUND

Lipid supplementation of ruminant diet is an excellent tool to improve the nutritional quality of dairy fat. The purpose of this research was to monitor in detail the goat milk fatty acid (FA) profile during the first 24 h after linseed oil (LO) supplementation or suppression in the diet. Particular emphasis was placed in the changes of FA with bioactive properties. Milk fat was analysed by gas chromatography from milkings at 0, 1, 3, 6, 12 and 24 h after diet shift.

RESULTS

The α-linolenic acid levels increased 12 h after LO incorporation in the diet and decreased 3 h after oil suppression. Most of the milk 10:0 to 16:0 saturated FA decreased 24 h after LO supplementation, whereas oil suppression raised their levels after 6 h. Similarly, raising of mono- and polyunsaturated trans-FA after LO inclusion was delayed in comparison with their decrease after oil suppression.

CONCLUSION

This study supports that ruminal bacteria and mammary glands would exhibit a fast responsiveness after the inclusion or suppression of LO in ruminant rations. Milk with an improved FA profile could be collected between 12 h after LO supplementation and the last milking before LO suppression in the diet. © 2018 Society of Chemical Industry.

Effects of dietary concentrate composition and linseed oil supplementation on the milk fatty acid profile of goats

Milk fat composition can be modulated by the inclusion of lipid supplements in ruminant diets. An interaction between the lipid supplement and the forage to concentrate ratio or the type of forage in the rations may affect milk fat composition. However, little is known about the effects of the starch-to-non-forage NDF ratio in the concentrate and lipid supplementation of goat diets. The aim of this work was to determine the role of dietary carbohydrates in goats rations supplemented with linseed oil on animal performance and milk fatty acid (FA) profile. A total of 16 dairy goats were allocated to two simultaneous experiments (two treatments each), in a crossover design with four animals per treatment and two experimental periods of 25 days. In both experiments alfalfa hay was the sole forage and the forage to concentrate ratio (33:67) remained constant. The concentrate in experiment 1 consisted of barley, maize and soybean meal (concentrate rich in starch), whereas it included soybean hulls replacing 25% of barley and 25% maize in experiment 2 (concentrate rich in NDF). As a result, the starch-to-non-forage NDF ratio was 3.1 in experiment 1 and it decreased to 0.8 in experiment 2. Both concentrates were administered either alone or in combination with 30 g/day of linseed oil. Animal performance parameters were not affected by experimental treatments. In contrast, major changes were observed in milk FA profile due to lipid supplementation and the type of concentrate. Linseed oil significantly raised vaccenic and rumenic acids as well as α-linolenic acid and its biohydrogenation intermediates while decreased medium-chain saturated FA (12:0 to 16:0) in milk fat. Milk fat contents of odd and branched-chain FA and trans-10 18:1 responded differently to linseed oil supplementation according to the concentrate fed.

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.

Diets supplemented with starch and corn oil, marine algae, or hydrogenated palm oil differentially modulate milk fat secretion and composition in cows and goats: A comparative study

A direct comparative study of dairy cows and goats was performed to characterize the animal performance and milk fatty acid (FA) responses to 2 types of diets that induce milk fat depression in cows as well as a diet that increases milk fat content in cows but for which the effects in goats are either absent or unknown. Twelve Holstein cows and 12 Alpine goats, all multiparous, nonpregnant, and at 86 ± 24.9 and 61 ± 1.8 DIM, respectively, were allocated to 1 of 4 groups and fed diets containing no additional lipid (CTL) or diets supplemented with corn oil [5% dry matter intake (DMI)] and wheat starch (COS), marine algae powder (MAP; 1.5% DMI), or hydrogenated palm oil (HPO; 3% DMI), according to a 4 × 4 Latin square design with 28-d experimental periods. Dietary treatments had no significant effects on milk yield and DMI in both species, except for COS in cows, which decreased DMI by 17%. In cows, milk fat content was lowered by COS (-45%) and MAP (-22%) and increased by HPO (13%) compared with CTL, and in goats only MAP had an effect compared with CTL by decreasing milk fat content by 15%. In both species, COS and MAP lowered the yields (mmol/d per kg of BW) of <C16 and C16 FA. With COS, this decrease was compensated by an increase of >C16 FA in goats, but not in cows, and the >C16 FA yield decreased with MAP in both species. HPO supplementation increased the milk yield of C16 FA in cows. Compared with CTL, COS induced an increase of trans-10,cis-12 conjugated linoleic acid by 18 fold in cows and 7 fold in goats and of trans-10 18:1 by 13 fold in cows and 3 fold in goats. Moreover, other conjugated linoleic acid isomers, such as trans-10,trans-12 and trans-7,cis-9, were increased to a greater extent in cows (8 and 4 fold, respectively) compared with goats (4 and 2 fold, respectively) on the COS treatment. In both species, the responses to MAP were characterized by a decrease in the milk concentration of 18:0 (3 fold, on average) and cis-9 18:1 (2 fold, on average) combined with a 3-fold increase in the total trans 18:1, with an increase in trans-10 18:1 only observed in cows. Compared with CTL, the response to HPO was distinguished by an increase in 16:0 (10%) in cows. This comparative study clearly demonstrated that each ruminant species responds differently to COS and HPO treatments, whereas MAP caused similar effects, and that goats are less sensitive than cows to diets that induce a shift from the trans-11 toward the trans-10 ruminal pathways.

Extruded linseed alone or in combination with fish oil modifies mammary gene expression profiles in lactating goats

Nutrition is a major factor that regulates ruminant milk components, particularly its fatty acid (FA) composition, which is an important determinant of milk nutritional quality. In the mammary gland, milk component biosynthesis involves a large number of genes under nutritional regulation that are not well understood. Thus, the objective of the present study was to evaluate the effects of extruded linseeds (EL) alone or in combination with fish oil (ELFO) on goat mammary gene expression. In total, 14 goats were fed one of the following three diets: a natural grassland hay basal diet (CTRL) alone, CTRL supplemented with 530 g/day of EL, or 340 g/day of EL plus 39 g/day of fish oil (ELFO). Mammary secretory tissues were collected after slaughter on day 28, to determine the expression of 14 lipogenic genes and five lipogenic enzyme activities and transcriptomic profiles. The mRNA abundance decreased for SCD1 (P<0.1) with ELFO v. CTRL, and for AZGP1 (P<0.1) and ACSBG1 (P<0.05) decreased with EL v. ELFO and the CTRL diets (only for ACSBG1), respectively. Transcriptomic analyses performed using a bovine microarray revealed 344 and 314 differentially expressed genes (DEG) in the EL and ELFO diets, respectively, compared with the CTRL diet, with 76 common DEGs. In total, 21 and 27 DEGs were involved in lipid metabolism and transport class in the EL and ELFO v. the CTRL diets, respectively, with eight common genes (ALDH3B1, ALDH18A1, DGKD1, ENPP1, IL7, NSMAF, PI4KA and SERINC5) down-regulated by these two treatments. In EL v. CTRL diets, a gene network related to lipid metabolism and transport was detected. Although this network was not detected in the ELFO v. CTRL analysis, five genes known to be involved in lipid metabolism and transport were up-regulated (SREBF1, PPARG and GPX4) or down-regulated (FABP1 and ENPP6) by ELFO. The protein metabolism and transport biological processes were largely altered by both EL and ELFO v. CTRL diets without changes in major milk protein secretion. Amino acid metabolism was highlighted as an enriched network by Ingenuity Pathway Analysis and was similar to cellular growth and proliferation function. Two regulation networks centered on the estrogen receptor (ESR1) and a transcriptional factor (SP1) were identified in EL and ELFO v. CTRL diets. In conclusion, these results show that these two supplemented diets, which largely changed milk FA composition, had more effects on mRNA linked to protein metabolism and transport pathways than to lipid metabolism, and could affect mammary remodeling.

trans-10,cis-12-Conjugated Linoleic Acid Affects Expression of Lipogenic Genes in Mammary Glands of Lactating Dairy Goats

The molecular mechanisms on milk fat depression (MFD) in response to trans-10,cis-12-conjugated linoleic acid (t10,c12-CLA) supplementation in ruminants were elucidated in this research with dairy goats. A total of 30 2-year-old Xinong Saanen dairy goats [40 ± 5 days in milk (DIM)] at peak lactation stage were assigned to a 3 × 3 Latin square design (14 day treatment period, followed with 14 day washout). Three CLA treatments included (a) control, fed the basal diet only without CLA supplementation; (b) orally supplemented with 8 g/day of lipid-encapsulated CLA (low dose, CLA-1); and (c) orally supplemented with 16 g/day of lipid-encapsulated CLA (high dose, CLA-2). Expression levels of fatty acid metabolism genes in the mammary tissues were analyzed by real-time quantitative polymerase chain reaction (RT-qPCR) in three goats on day 1 and the other three goats on day 14 in each group after the discontinuation of CLA treatment in the third experimental period. Dietary supplementation of CLA led to a significant decrease of milk fat compared to the control (p < 0.05). Milk fat concentrations in CLA-1 and CLA-2 groups were 2.74 and 2.42%, respectively, while the milk fat concentration in the control group was 2.99%. Decreases in short- and medium-chain fatty acids (<16 carbons) and increases in unsaturated fatty acids were observed in the CLA-2 group (p < 0.05). The desaturation indexes of C16 and C18 fatty acids were obviously increased (p < 0.01). RT-qPCR results revealed decreases of the mRNA expression levels of SREBF1, PPARG, LPL, CD36, FABP3, ACSL1, FASN, ACACA, DGAT2, TIP47, ADRP, and BTN1A1 genes in mammary glands (p < 0.05) and an increase of the SCD gene because of CLA supplementation (p < 0.05). In conclusion, t10,c12-CLA-induced MFD was possibly the result from the downregulation of genes involved in lipogenesis in goat mammary glands.

Production of trans and conjugated fatty acids in dairy ruminants and their putative effects on human health: A review

Consumption of milk and dairy products is important in Western industrialised countries. Fat content is an important constituent contributing to the nutritional quality of milk and dairy products. In order to improve the health of consumers, there is high interest in improving their fatty acid (FA) composition, which depends principally on rumen and mammary metabolism. This paper reviews the lipid metabolism in ruminants, with a particular focus on the production of trans and conjugated linoleic acids (CLA) and conjugated linolenic acids (CLnA) in the rumen. After the lipolysis of dietary lipids, an extensive biohydrogenation of unsaturated FA occurs by rumen bacteria, leading to numerous cis and trans isomers of 18:1, non-conjugated of 18:2, CLA and CLnA. The paper examines the different putative pathways of ruminal biohydrogenation of cis9-18:1, 18:2n-6, 18:3n-3 and long-chain FA and the bacteria implicated. Then mechanisms relative to the de novo mammary synthesis are presented. Ruminant diet is the main factor regulating the content and the composition of milk fat. Effects of nature of forage and lipid supplementation are analysed in cows and small ruminants species. Finally, the paper briefly presents the effects of these FA on animal models and human cell lines. We describe the properties of ruminant trans 18:1, when compared to industrial trans 18:1, CLA and CLnA on human health from meta-analyses of intervention studies and then explore the underlying mechanisms.

Effect of supplementary glycerin on milk composition and heat stability in dairy goats

Objective

This experiment was studied the effects of various levels of crude glycerin (CG) in dairy goat diet on daily intake, milk yield, milk composition, some physical properties and some quality changes of goat milk after sterilization.

Methods

Twelve 75% Saanen dairy goats (body weight = 49±3 kg; days in milk = 60±12 d) were randomly assigned in a completely randomized design to evaluate the effects of three experimental diets consisting of 0%, 5%, and 10% CG (dry matter basis) which were formulated to meet or exceed the nutrient requirements of goats. Experimental dairy goats were evaluated for feed and milk yield. Milk samples were analyzed for their composition, including fatty acids, casein profile, fat globule size, and color, and were sterilized to evaluate milk heat stability.

Results

There were no significant differences between 0% and 5% CG treatments infeed. Increasing CG supplementation from 0% to 5% increased milk yield from 2.38±0.12 to 2.64±0.23 kg/goat/d. In addition, milk samples from 5% CG treatment had the highest total solids, fat content and lactose content, and largest fat globule size. Increasing CG to 10% resulted in a decrease in milk fat. After sterilizing at 116°C, F₀ = 3 min, goat milk samples from 5% CG treatment had slightly higher sediment content and comparatively higher degree of browning.

Conclusion

Considering milk yield, milk fat content and quality of sterilized milk, 5% CG supplementation in a total mixed ration has a potential for implementation in dairy goats.

Comparison of ruminal lipid metabolism in dairy cows and goats fed diets supplemented with starch, plant oil, or fish oil

Direct comparison of cow and goat performance and milk fatty acid responses to diets known to induce milk fat depression (MFD) in the bovine reveals relevant species-by-diet interactions in ruminal lipid metabolism. Thus, this study was conducted to infer potential mechanisms responsible for differences in the rumen microbial biohydrogenation (BH) due to diet and ruminant species. To meet this objective, 12 cows and 15 goats were fed a basal diet (control), a similar diet supplemented with 2.2% fish oil (FO), or a diet containing 5.3% sunflower oil and additional starch (+38%; SOS) according to a 3 × 3 Latin square design with 25-d experimental periods. On the last day of each period, fatty acid composition (by gas chromatography) and bacterial community (by terminal-RFLP), as well as fermentation characteristics, were measured in rumen fluid samples. Results showed significant differences in the response of cows and goats to dietary treatments, although variations in some fermentation parameters (e.g., decreases in the acetate-to-propionate ratio due to FO or SOS) were similar in both species. Main alterations in ruminal BH pathways potentially responsible for MFD on the SOS diet (i.e., the shift from trans-11 to trans-10 18:1 and related increases in trans-10,cis-12 18:2) tended to be more pronounced in cows, which is consistent with an associated MFD only in this species. However, changes linked to FO-induced MFD (e.g., decreases in 18:0 and increases in total trans-18:1) were stronger in caprine rumen fluid, which may explain their unexpected susceptibility (although less marked than in bovine) to the negative effect of FO on milk fat content. Altogether, these results suggest that distinct ruminal mechanisms lead to each type of diet-induced MFD and confirm a pronounced interaction with species. With regard to microbiota, differences between cows and goats in the composition of the rumen bacterial community might be behind the disparity in the microorganisms affected by the experimental diets (e.g., Ruminococcaceae, Lachnospiraceae, and Succinivibrionaceae in the bovine, and Pseudobutryrivibrio, Clostridium cluster IV, Prevotella, and Veillonellaceae in the caprine), which hindered the assignation of bacterial populations to particular BH steps or pathways. Furthermore, most relevant variations in microbial groups corresponded to as yet uncultured bacteria and suggest that these microorganisms may play a predominant role in the ruminal lipid metabolism in both cows and goats.

Comparison of the nutritional regulation of milk fat secretion and composition in cows and goats

A study with 2 ruminant species (goats and cows) with inherent differences in lipid metabolism was performed to test the hypothesis that milk fat depression (MFD) due to marine lipid supplements or diets containing high amounts of starch and plant oil is caused by different mechanisms and that each ruminant species responds differently. Cows and goats were allocated to 1 of 3 groups (4 cows and 5 goats per group) and fed diets containing no additional oil (control) or supplemented with fish oil (FO) or sunflower oil and wheat starch (SOS) according to a 3 × 3 Latin square design with 26-d experimental periods. In cows, milk fat content was lowered by FO and SOS (-31%), whereas only FO decreased milk fat content in goats (-21%) compared with the control. Furthermore, FO and SOS decreased milk fat yield in cows, but not in goats. In both species, FO and SOS decreased the secretion of <C16 and C16 fatty acids (FA), and FO lowered >C16 FA output. However, SOS increased milk secretion of >C16 FA in goats. Compared with the control, SOS resulted in similar increases in milk trans-10,cis-12 conjugated linoleic acid (CLA) in both species, but caused a 2-fold larger increase in trans-10 18:1 concentration in cows than for goats. Relative to the control, responses to FO in both species were characterized by a marked decrease in milk concentration of 18:0 (-74%) and cis-9 18:1 (-62%), together with a ~5-fold increase in total trans 18:1, but the proportionate changes in trans-10 18:1 were lower for goats. Direct comparison of animal performance and milk FA responses to FO and SOS treatments demonstrated interspecies differences in mammary lipogenesis, suggesting a lower sensitivity to the inhibitory effects of trans-10,cis-12 CLA in goats and that ruminal biohydrogenation pathways are more stable and less prone to diet-induced shifts toward the formation of trans-10-containing intermediates in goats compared with cows. Even though a direct cause and effect could not be established, results suggest that regulation of milk fat synthesis during FO-induced MFD may be related to a shortage of 18:0 for endogenous mammary cis-9 18:1 synthesis, increase in the incorporation of trans FA in milk triacylglycerols, and limitations in the synthesis of FA de novo to maintain milk fat melting point. However, the possible contribution of biohydrogenation intermediates with putative antilipogenic effects in the mammary gland, including trans-9,cis-11 CLA, trans-10 18:1, or cis-11 18:1 to FO-induced MFD cannot be excluded.