Pier Lorenzo Secchiari

Effect of kind of dietary fat on the quality of milk fat from Italian Friesian cows

Four diets, supplemented with different fats of vegetable origin, were compared in a 4×4 Latin square design with eight primiparous Italian Friesian cows (two cows per cell). The four fats were: toasted full fat soy bean in diet WS; toasted full fat linseed in diet WL; calcium soap of palm oil in diet PS; and calcium soap of olive oil in diet OS. Scope of the trial was to study the effect of the four different fat sources on milk yield and composition and on the quality of milk fat in terms of safety for the consumer health, with particular attention to trans fatty acids and to conjugated linoleic acid isomers (CLA). Diet OS induced the highest milk yield (P<0.05), while diet PS gave the fattest milk (P<0.05), and the highest milk content of both saturated and medium chain fatty acids (P<0.05). Saturated to unsaturated ratio of milk fat was decreased when cows were fed diet WS (P<0.05), while the ratio was increased with cows fed on diet PS (P<0.05). With a closely similar behaviour milk CLA content was enhanced with diet WS and strongly depressed (P<0.05) with diet PS. Diet OS increased total CLA as well, probably as a consequence of the bio-hydrogenation process of large amounts of oleic acid, transformed into trans isomers of C18:1, including vaccenic acids. Full fat soy bean promoted some milk fatty acids with beneficial effects on consumer health, but calcium soap of olive oil similarly improved the fatty acid profile of milk fat, while meeting the cows’ requirements as an energy supplement.

Genetic parameters for conjugated linoleic acid, selected milk fatty acids, and milk fatty acid unsaturation of Italian Holstein-Friesian cows.

The objective of this study was to estimate genetic parameters for conjugated linoleic acid (CLA) and other selected milk fatty acid (FA) content and for unsaturation ratios in the Italian Holstein Friesian population. Furthermore, the relationship of milk FA with milk fat and protein content was considered. One morning milk sample was collected from 990 Italian Holstein Friesian cows randomly sampled from 54 half-sib families, located in 34 commercial herds in the North-eastern part of Italy. Each sample was analyzed for milk percentages of fat and protein, and for single FA percentages (computed as FA weight as a proportion of total fat weight). Heritabilities were moderate for unsaturated FA, ranging from 0.14 for C16:1 to 0.19 for C14:1. Less than 10% of heritability was estimated for each saturated FA content. Heritability for index of desaturation, monounsaturated FA and CLA/trans-11 18:1 ratio were 0.15, 0.14, and 0.15, respectively. Standard errors of the heritability values ranged from 0.02 to 0.06. Genetic correlations were high and negative between C16:0 and C18:0, as well as between C14:0 and C18:0. Genetic correlations of index of desaturation were high and negative with C14:0 and C16:0 (-0.70 and -0.72, respectively), and close to zero (0.03) with C18:0. The genetic correlation of C16:0 with fat percentage was positive (0.74), implying that selection for fat percentage should result in a correlated increase of C16:0, whereas trans-11 C18:1 and cis-9, trans-11 C18:2 contents decreased with increasing fat percentage (-0.69 and -0.55, respectively). Genetic correlations of fat percentage with 14:1/14 and 16:1/16 ratios were positive, whereas genetic correlations of fat percentage with 18:1/18 and CLA/trans-11 18:1 ratios were negative. These results suggest that it is possible to change the milk FA composition by genetic selection, which offers opportunities to meet consumer demands regarding health aspects of milk and dairy products.

Sheep cheese naturally enriched in α-linolenic, conjugated linoleic and vaccenic acids improves the lipid profile and reduces anandamide in the plasma of hypercholesterolaemic subjects

Intake of dairy fat has long been considered as a risk factor for CVD. Pasture and dietary lipid supplementation have been reported to be reliable strategies in ruminant nutrition, in order to increase the content of α-linolenic acid (ALA), conjugated linoleic acid (CLA) and vaccenic acid (VA), and decrease SFA in milk fat. In the present study, we aimed at verifying whether consumption of a sheep cheese, naturally enriched in ALA, CLA and VA, would modify the plasma lipid and endocannabinoid profiles in mildly hypercholesterolaemic subjects. A total of forty-two adult volunteers (nineteen males and twenty-three females) with diagnosed mildly hypercholesterolaemia (total cholesterol 5·68-7·49 mmol/l) were randomly assigned to eat 90 g/d of a control or enriched cheese for 3 weeks, with a cross-over after 3 weeks of washout. Plasma lipids, endocannabinoids, adipokines and inflammatory markers were measured. The intake of enriched cheese significantly increased the plasma concentrations of CLA, VA, the n-3 fatty acids ALA and EPA, and more remarkably decreased that of the endocannabinoid anandamide. LDL-cholesterol decreased significantly (7%). No changes were detected in the levels of inflammatory markers; however, a significant correlation was found between the plasma levels of anandamide and leptin. The control cheese modified none of the parameters measured. The results obtained do not support the view that intake of dairy fat is detrimental to hypercholesterolaemic subjects. Indeed, they show that a naturally enriched cheese possesses beneficial properties, since it ameliorates the plasma lipid profile, and more remarkably reduces endocannabinoid biosynthesis.

Association Between a Polymorphism at the Stearoyl-CoA Desaturase Locus and Milk Production Traits in Italian Holsteins

Associations between stearoyl-CoA desaturase (SCD) gene polymorphisms and milk production traits (milk, fat, and protein yields, fat and protein contents, somatic cell score) were investigated on a sample of 701 lactations of 313 Italian Holsteins. Test-day records (5,097) were analyzed with a mixed linear model that included the fixed effects of herd, date of test, parity, genotype at the SCD locus, and lactation interval nested within SCD genotype, and the random effect of cow. An effect of the SCD genotype on milk and protein yields was detected, with VV cows producing more milk (about 2 kg/d) and protein (about 0.07 kg/d) compared with AA cows. The contribution of the SCD locus to the phenotypic variance of the 2 traits was about 0.015. These results suggest a possible use of the SCD locus in gene-assisted selection programs for the improvement of milk production traits in dairy cattle, although large-scale studies in different breeds are required.

Diacylglycerol acyltransferase 1, stearoyl-CoA desaturase 1, and sterol regulatory element binding protein 1 gene polymorphisms and milk fatty acid composition in Italian Brown cattle.

Several lipogenic genes have been shown to have effects on lipid metabolism: stearoyl CoA desaturase 1 (SCD1) catalyzes the desaturation of several fatty acids (FA) in the cis-Delta(9) position in mammary glands of ruminant animals, diacylglycerol acyltransferase 1 (DGAT1) is a key enzyme in triacylglycerol synthesis in the mammary gland, and sterol regulatory element binding protein (SREBP-1) is a transcription factor that regulates expression levels of the SCD1 gene and other genes relevant to lipid and FA metabolism in adipose tissue and mammary gland. In this work, 351 Italian Brown cows were genotyped for polymorphisms in the SCD1, SREBP-1, and DGAT1 genes to reveal the allelic distribution in the population. Subsequently, effects on individual milk FA composition and on cis-9 unsaturated/saturated FA ratios, a proxy of mammary stearoyl CoA desaturase activity, were investigated. The genotypes of SCD1 (A293V) and DGAT1 (K232A) were determined by an approach based on the ligation detection reaction and a universal array, whereas the genotype of SREBP-1 (84-bp insertion-deletion) was revealed by PCR amplification of intron 5. The genotype analysis showed an unbalanced distribution of alleles within all genes, being the allele with higher gene frequency at 82, 84, and 98% for SCD1, SREBP-1, and DGAT1, respectively. Significant associations between SCD1 and DGAT1 polymorphisms and milk FA composition were found, whereas SREBP-1 polymorphism was not associated with milk FA composition. In particular, SCD1 showed significant association with C14:1 cis-9 and C14:1 cis-9/C14:0, which is considered the best proxy of the desaturation activity in mammary gland. The DGAT1 polymorphism had the strongest association with milk FA composition, which confirmed the key role of DGAT1 in lipid metabolism of mammary gland. However, the unbalanced distribution of alleles in all polymorphisms investigated suggested that the size of population should be increased to confirm the results of the present study.

Effect of soybean oil supplementation on milk fatty acid composition from Saanen goats fed diets with different forage:concentrate ratios

Abstract Twelve lactating Saanen goats were randomly assigned to four experimental diets, which differed in terms of forage:concentrate ratio and soybean oil supplementation. A 4×4 Latin square design was used. On a dry matter (DM) basis, forage:concentrate ratios were 63:37 (‘high-forage’ diet) and 35:65 (‘low-forage’ diet/high beet pulp). These diets were given either with oil (100 g·d-1) or without. The inclusion of soybean oil in the diet resulted in a significant increase in milk yield (but with HF diet) and in milk fat yield and concentration (P<0.05). Milk protein content remained unchanged across the diets. Milk protein yield was, however, higher for the high-forage diet containing added oil (forage × oil interaction, P<0.05). Soybean oil in the diet modified the milk fatty acid composition, reducing the levels of medium-chain and saturated fatty acids and increasing the levels of C18:2 n-6 and conjugated linoleic acid (CLA). The addition of soybean oil to the diet resulted in a significant increase in rumenic acid (cis-9, trans-11 CLA) and vaccenic acid (trans-11 C18:1) content in the milk fat. Interactions between forage and oil resulted in a significant increase in rumenic acid and vaccenic acid in animals fed a high-forage plus oil diet, and in trans-10 C18:1and trans-10, cis-12 CLA in animals fed a low-forage plus oil diet, probably due to a shift in the rumen’s biohydrogenation of linoleic acid.

Conjugated Linoleic Acid (CLA) content of meat from three muscles of Massese suckling lambs slaughtered at different weights

Eighteen Massese male lambs, fed mainly maternal milk were slaughtered at 11, 14 and 17kg. Samples of Longissimus Dorsi (LD), Triceps Brachii (TB) and Semimembranosus (Sm) muscles were collected. Milk from the lambs dams was sampled weekly. Fatty acid composition of milk and meat was determined. TB was the fattest muscle, Sm the leanest one and LD showed an intermediate value of total lipids, while the weight at slaughter did not influence total intramuscular fat content in any muscle. Although slaughter weight slightly affected overall fatty acid composition of muscles, rumenic acid and total CLA content in TB and Sm, but not in LD, significantly increased with slaughter weight. As regard milk fatty acid composition, the contents of total CLA, RA and others minor CLA isomers decreased during the first four weeks after lambing and then increased at the last control (five weeks). The animals slaughtered at a live weight of 14 and 17kg showed a greater SCD enzyme activity (estimated by product/substrate ratio) and a higher rumen activity (estimated by means of branched chain and odd chain fatty acid content in meat) than animals slaughtered at 11kg. Cis-7, trans-9 CLA content significantly increased with the slaughter age in TB and SM, while trans-7, trans-9 CLA, only increased in TB, and cis-8, cis-10 CLA, only increased in SM. Further studies are needed in order to verify weather the different behaviour of RA in LD muscle may be due to differences in muscle metabolism or fatty acid utilisation.

Upgrading the lipid fraction of foods of animal origin by dietary means: rumen activity and presence of trans fatty acids and CLA in milk and meat

Abstract The recent literature dealing with the effect of the diet on the quality of milk and meat fat is reviewed. Some aspects of the rumen metabolism of lipids are dealt with: lipolysis, bio-hydrogenation, synthesis of microbial fatty acids and inhibition mechanisms on fermentation. Firstly, the influence of forage is considered. Pasture is the best forage, better if high hill pasture, as compared to hay and silage: short chain fatty acids (SCFA) (shorter than C10) are increased, medium chain fatty acids (MCFA) (C12 through C16) are decreased, oleic (OA), linoleic (LA) and linolenic (LNA) acids are increased and so are the conjugated linoleic acid pool of isomers (CLA) and n-3 polyunsaturated fatty acids (n-3 PUFA). Secondly, the energy supplementation of diets with fats is looked at. Animal fats depress milk yield and SCFA, while OA is increased because of the enhanced activity of mammary ∆9 desaturase. Fish oil depresses milk yield as well, but promotes CLA and n-3 PUFA. If animal fats are protected against rumen bacteria, milk yield and milk fat depression are avoided. Vegetable fats are richer in unsaturated fatty acids (UFA), thus more susceptible to the rumen bio-hydrogenation. As calcium soaps or inside whole seeds, plant fats are protected and CLA is increased. CLA is an important component of fat. In ruminants it comes from the desaturation of vaccenic acid (VA) both in rumen and udder; and the yield of VA depends on the diet quality. In conclusion, simple directions are given on how to improve the quality of animal fat by dietary means, without affecting yield.

Short communication: Effects of β-lactoglobulin, stearoyl-coenzyme A desaturase 1, and sterol regulatory element binding protein gene allelic variants on milk production, composition, acidity, and coagulation properties of Brown Swiss cows

Associations of allelic variants of the β-lactoglobulin (LGB), stearoyl-coenzyme A desaturase 1 (SCD), and sterol regulatory element binding protein (SREBP-1) genes with milk production, composition (fat, protein, and casein content), acidity (pH and titratable acidity), and coagulation properties (rennet coagulation time and curd firmness) were investigated in Brown Swiss cows. In total, 294 animals (progeny of 15 sires) reared in 16 herds were milk-sampled once. The additive effects of LGB (rs109625649:C>T), SCD (ss469414220:C>T), and SREBP-1 (AB355704: g.101_185ins) polymorphisms on the aforementioned traits were analyzed through Bayesian linear models. The LGB genotype affected rennet coagulation time, with TT (or BB) alleles showing longer rennet coagulation time compared with CC (or AA) cows. The SCD gene allelic variants were found to be associated with protein and casein contents and curd firmness: CC animals had the lowest values for the aforementioned traits. An association was found between SREBP-1 alleles and fat content, with the highest values for cows carrying the 84-bp insertion (or L) allele. Results suggest a possible use of these loci in gene-assisted selection programs for the improvement of milk quality traits and coagulation properties in Brown Swiss cattle.

Olive oil calcium soaps and rumen protected methionine in the diet of lactating ewes: effect on milk quality

Abstract Eight Massese ewes were fed 4 diets with alfalfa hay as the forage (73% on the DM basis): 1) control diet (C); 2) diet C supplemented with olive oil calcium soaps, 50 g/d (L); 3) diet C supplemented with protected methionine, 5 g/d (M) or 4) plus both soaps and methionine (ML); the experimenthal design was a 4x4 Latin square with 2 replicates per diet. During the experimental periods, lasting one week each, the ewes were milked twice daily (8:00 a.m. and 7:00 p.m.). Milk yield was not affected by diet quality, but milk fat percentage and 6.5% fat corrected milk yield were higher in diets L, M and ML with respect to diet C (P<0.05). Milk protein content was depressed and blood urea increased following the Ca soap diet alone or with protected methionine. Diet M worsened (P<0.05) Rennet clotting time (r) and curd firmness after 30 minutes (A30). Saturated fatty acids C10:0, C12:0, C14:0 and C16:0 were depressed in milk fat with the Ca soap supplemented diet, some of them significantly. C18:1 increased (P<0.05) with diet L only, whereas the association of Ca salts and methionine in diet ML significantly affected the linoleic acid and CLA content. It is concluded that the use of olive oil fatty acids as a protected fat source seems to improve the milk fatty acid characteristics towards a safer pattern, but the presence of this type of Ca salts in the diet appears to worsen the metabolic utilisation of amino acids.