Goat Milk Fatty Acid Composition Research Articles

Goat milk fatty acid composition in the Peninsula of Baja California, Mexico

ABSTRACTObjective. The objective of the study was to determine the composition of fatty acids in milk of Creole goats in an extensive production system in an arid region of the peninsula of Baja California and compare it to two seasons of the year (rainy and dry). Materials and methods. Sampling was conducted during the dry season (June) and after the rainy season (December) in the municipality of Comondú in Baja California Sur. The extensive production system used involved releasing goats to roam freely in the rangeland to graze for food, and no additional food or supplements were provided. Results. The most abundant fatty acids were saturated fatty acids (66.3 and 70.9% in the rainy and dry reasons, respectively). The most abundant of these were palmitic, myristic, and stearic acid in both seasons. Monounsaturated fatty acids (15-20%) were the most numerous in terms of isomers, but mostly in low concentrations. The largest average constituent of polyunsaturated fatty acids (5-6%) was linoleic acid (3%) and alpha-linolenic acid (1.2%) in both seasons. Branched, fatty acid concentrations were highly variable; the only stable constituents were C15:0 iso (1.5%) and C16:0 anti-iso, with 0.7% of total fatty acids. Conclusions. The seasons in this extensive production system significantly effected the composition of most monounsaturated and branched fatty acids in goat milk; however, saturated and polyunsaturated showed only a few compositional changes in abundance of fatty acids. Moreover, season effects were not significant on the total fatty acid content, except for branched fatty acids and omega-3.

Prediction of the goat milk fatty acids by near infrared reflectance spectroscopy

AbstractNear infrared reflectance spectroscopy (NIRS) was used to predict the goat milk fatty acid (FA) profile. The ability of cow milk broad‐based calibration equations to predict the goat milk FA profile was assessed. Three hundred twenty‐eight samples in the calibration set and 108 in the validation set were analyzed. We showed that the bias and unexplained error were significant for most of the FA despite an adequate standardized Mahalanobis distance (index to establish the boundaries of a population of samples) which allowed us to test the ability of bovine models to predict goat milk FA profiles. To better predict the goat milk FA composition, a specific goat model was investigated. The cross‐validation coefficient of determination (R2CV; proportion of variance explained by the model in cross‐validation) and residual predictive deviation (RPD; index which allows to standardize the standard error of prediction (SEP)) were >0.90 and 3, for saturated, monounsaturated, and unsaturated FA, total trans FA, isomer cis9trans11 of CLA, cis9‐, trans10‐, and trans11‐C18:1, respectively. Monitoring of the equation performance of milk FA included the calculation of the bias and unexplained error.Practical applications: In this work, we evaluated the ability of NIRS to predict FA composition of goat milk and tested the ability of using broad‐based cow milk calibration equations to monitor an independent set of goat milk samples. We tested the hypothesis that the calibration equations obtained for FA from cow milk could be applied on goat milk. As the spectra of goat milk are similar to those of cow milk when they are measured by the standardized Mahalanobis distance (index to establish the boundaries of a population of samples), we can accept the hypothesis. It will be possible to use the existing calibration equations for predicting FA profile on spectra of milk of a different specie. However, the rejection of the hypothesis would put in doubt the use of Mahalanobis distance as the unique index for testing the performance of calibration equations on different milk populations for predicting FA.

Changes in goat milk fatty acids during abrupt transition from indoor to pasture diet

Goal of this study was to evaluate the kinetics of goat milk fatty acids during abrupt transition from indoor to pasture-based diets. Twelve Valdostana goats in mid-lactation reared indoors and fed hay and concentrates for 40days were abruptly brought outdoors on natural pasture and fed fresh grass ad libitum. Feed samples and individual milk samples were collected for fatty acids analysis on the last day of indoor feeding (day 0) and after 1, 2, 3, 4, 6, 9, 13, 18 and 23days of fresh grass feeding. Milk fatty acid composition was significantly affected by sampling day. Significant changes already took place few days after transition. The most marked and consistent variations occurred at the expense of some unsaturated fatty acids. Total trans-octadecenoic and trans-octadecadienoic acids, conjugated linoleic acids (CLA) and omega-3 fatty acids constantly increased, reaching concentrations 4.0, 3.0, 3.9, and 2.2 times higher at the end of the trial than at its beginning, respectively. On the last sampling day the omega-6/omega-3 fatty acids ratio was two times lower than its initial value. Considering individual fatty acids, the most consistent and remarkable increasing trends throughout the trial were observed for C18:1 t6–11, C18:1 t12–14+c6–8, C18:1 c14+t16, C18:2 t11c15, C18:2 c9t13+t8c12, CLA isomers c9t11+t7c9+t8c10 and t11c13+c9c11. Alpha-linolenic and eicosapentaenoic acids also increased significantly, but to a lesser extent. In view of the many beneficial biological effects that have been attributed to vaccenic acid (C18:1 t11), rumenic acid (C18:2 c9t11), and omega-3 fatty acids, results showed that, from a human health perspective, goat milk fatty acid composition consistently improved after transition from indoor to pasture feeding. Such improvements, mainly due to the high content of α-linolenic acid in pasture plants, were already significant after two or three days of fresh grass feeding. Further increases of beneficial fatty acids in milk fat were observed till about thirteen (vaccenic acid and CLA) or twenty-three (omega-3 fatty acids) days after transition. These results show that pasture can be considered a natural feeding strategy to quickly enhance the healthfulness of goat milk fat.

Polymorphism at α s1-casein locus. Effect of genotype × diet interaction on milk fatty acid composition in Girgentana goat

Eighteen Girgentana lactating goats, nine homozygous for strong alleles (AA) and nine homozygous for weak alleles (FF) at α s1-casein locus, were used to evaluate the effect of genotype × diet interaction on goat milk fatty acid composition. Animals were divided in two groups. First group consisted of 5 AA and 4 FF, the second one consisted of 4 AA and 5 FF animals. The experimental groups were used in a 2 × 2 factorial arrangement of treatments, with two genotypes (AA, FF) and two diets (D100 and D65) at different energy level (1099 and 1386 kcal NEl/kg), obtained with 100% and 65% of pelleted alfalfa hay inclusion, respectively. All the animals were housed in individual pens. The genotype × diet interaction was significant ( P < 0.05) for 11 different milk fatty acids. In particular, C8:0, C10:0, C12:0, C14:0 increased when FF animals shifted from D100 to D65, while the same fatty acids did not significantly change in AA animals; moreover, percentage of palmitic acid (C16:0) was significantly lower in animals with strong genotype when fed the high energy diet. Shifting from D100 to D65, long chain fatty acids (>C18) significantly increased in AA and decreased in FF goat milk. In conclusion, goats homozygous for weak and strong alleles at αs 1-casein locus seem to respond in a different way when fed diets with different energy levels; in particular, receiving a high energy diet, AA goats did not show any remarkable effect on milk fat quality, whereas FF goats showed a worsening in fat nutritional value.

Relationships between the contents of vaccenic acid, CLA and n − 3 fatty acids of goat milk and the muscle of their suckling kids

The relationship between goat milk fatty acid composition, especially trans-11 C18:1 (vaccenic acid, VA), conjugated linoleic acid (CLA) and n − 3 fatty acids, and that of the meat from their suckling kids was investigated by feeding the dams a diet supplemented with whole cottonseed (COT) or extruded linseed (LIN). Fifteen Sarda goats, fed 1.2 kg/day per head of concentrate and hay ad libitum, were divided into two groups and supplemented during weeks 4 and 5 post-partum with 32 g/day per head of fat from LIN and COT, which have high C18:3 and C18:2 content, respectively. Fifteen kids were fed exclusively by suckling maternal milk until slaughtering (at 9–10 kg of body weight and approximately 6 weeks of age). Twenty-four hour after slaughter, the longissimus dorsi (LD) muscle was removed from each carcass. Fatty acid profiles of milk and LD were significantly affected by diets. Compared to COT, feeding LIN changed the milk fatty acid profiles by decreasing the proportion of C16:0 and increasing the contents of VA, C18:3 n − 3 (linolenic acid) and total CLA, including cis-9, trans-11-, trans-11, cis-13-, trans-11, trans-13- and trans, trans isomers. The concentrations of VA, cis-9, trans-11 C18:2 (rumenic acid, RA) and linolenic acid in milk and those in kid muscle were strongly correlated. The fatty acid profile of meat from suckling kids was effectively modified by manipulating the diet of the dams.

Effect of a Diet Enriched in Whole Linseed and Sunflower Oil on Goat Milk Fatty Acid Composition and Conjugated Linoleic Acid Isomer Profile

The aim of the present research was to study changes in milk composition and fatty acid profile, specifically conjugated linoleic acid (CLA) and its isomers, in goat milk as affected by dietary supplementation of sun-flower oil and whole linseed (0.81 and 1.84% of dry matter on basal diet, respectively) and to assess the persistency of the response. To achieve this objective, bulk milk from a herd and from 6 individual dairy goats fed a diet supplemented with sunflower oil and whole linseed was monitored for a period of 3 mo. Gas chromatography and silver ion HPLC were used to analyze total CLA content and the isomeric profile of these fatty acids, respectively. The contents of α-linolenic acid increased from 0.35% with the reference diet to 0.62% with the supplemented diet. Similarly, CLA milk content increased from 0.46 to 1.18%. The same pattern was also observed for trans-11 C18:1 (1.38 to 4.05%, respectively) in goat milk after 3 mo of lipid supplementation. In contrast, changes in other trans C18:1 isomers were less remarkable. There was a strong linear correlation between cis-9, trans-11 C18:2, the main CLA isomer, and trans-11 C18:1 under the conditions assayed and their concentration remained stable throughout the duration of the study. Levels of the minor CLA isomers were also enhanced as a consequence of lipid supplementation. The most remarkable increases were observed for 11–13 (trans-trans and trans-cis geometric isomers), whereas trans-7, cis-9 (the second most important CLA isomer from a quantitative point of view) and trans-10, cis-12 increased only slightly with lipid supplementation.

Dietary lipids and forages interactions on cow and goat milk fatty acid composition and sensory properties

This review summarises the known effects of dietary factors on bovine and caprine milk fatty acid composition, as well as the regulation of cow and goat mammary lipid secretion. Special attention is given to fatty acids that could play a role for human health, such as saturated fatty acids, oleic acid, n-6- or n-3-C18 to C22 polyunsaturated fatty acids, trans isomers of C18:1 and C18:2, and isomers of conjugated linoleic acid (CLA). The main dietary factors taken into account are the nature of forages, including pasture, the forage:concentrate ratio and diet starch content, and the supplementation of dairy rations with crude or processed vegetable oils or oilseeds, and vitamin E. A particular emphasis is given to studies on interactions between these dietary factors, which show that there is a considerable plasticity of ruminant milk fatty acid composition. Despite the existence of several studies on the effects of dietary factors on the sensorial quality of milk and dairy products, there is a need to evaluate more deeply how the different feeding strategies could change the nutritional, sensorial and technological aspects of milk fat quality.