Effect of diets containing n-3 fatty acids on muscle long-chain n-3 fatty acid content in lambs fed low- and medium-quality roughage diets

In two experiments, each with 32 cross-bred ([Merino x Border Leicester] x Poll Dorset) wether lambs (26 to 33 kg weight range), animals were randomly assigned to one of four treatments. A mixture of lucerne chaff:oaten chaff was used as a basal diet, offered in different ratios. Animals were allowed to consume on a free-access basis in Exp. 1 or 90% of ad libitum intake in Exp. 2 in order to provide a low- (6.5 MJ ME/d) and medium- (9.5 MJ ME/d) quality basal diet, respectively. Isoenergetic amounts of lipid supplements, fish meal (80 g DM), canola meal (84 g DM), and soy meal (75 g DM) were tested in Exp. 1. In Exp. 2, fish meal (9% DM), unprotected rapeseed (7% DM), and protected canola seed (6% DM) were fed as supplements. At the end of 53-d (Exp. 1) or 46-d (Exp. 2) experimental periods, lambs were slaughtered at a commercial abattoir and at 24 h postmortem longissimus thoracis (LT) muscle was collected for the analysis of fatty acid (FA) composition of structural phospholipid and storage triglyceride fractions. Fish meal diet increased LT muscle long-chain n-3 FA content by 27% (P < 0.02) in Exp. 1 and 30% (P < 0.001) in Exp. 2 compared with lambs fed the basal diet, but fish meal decreased (P < 0.01) the n-6 FA content only in Exp. 1. Soy meal and protected canola seed diets increased (P < 0.01) LT muscle n-6 FA content but did not affect long-chain n-3 FA content. Longissimus thoracis muscle long-chain n-3 FA were mainly deposited in structural phospholipid, rather than in storage triglyceride. In both Exp. 1 and Exp. 2, the ratio of n-6:n-3 FA in LT muscle was lowest (P < 0.01) in lambs fed fish meal supplement compared with all other treatments. Protected canola seed diet increased the ratio of n-6:n-3 FA (P < 0.01) and PUFA:saturated fatty acid (P < 0.03) content from those animals fed the basal, fish meal, and unprotected rapeseed diets in Exp. 2. This was due to an increase in muscle n-6 FA content, mainly linoleic acid, of both phospholipid (P < 0.001) and triglyceride (P < 0.01) fractions and not to an increase in muscle n-3 FA content. The results indicate that by feeding fish meal supplement, the essential n-3 FA can be increased while lowering the ratio of n-6:n-3 content in lamb meat to an extent that could affect nutritional value, attractiveness, and the economic value of meat.     

Influence of rapeseed meal, whole rapeseed, and soybean meal on fatty acid composition and cholesterol content of muscle and adipose tissue from ram lambs.

Twenty-four Suffolk x Hampshire ram lambs (average 46 kg) were assigned to one of three diets containing rapeseed meal (RM), soybean meal (SBM), or whole rapeseed-soybean meal (RSSBM) as the protein source. Diets contained 75% roughage, 14% CP and 2.0 Mcal of ME/kg and lambs were allowed ad libitum access to diets for 35 d. Lipid composition of the longissimus, semimembranosus, and triceps brachii muscles and their corresponding s.c. adipose tissue was determined by gas-liquid chromatography (GLC). The total lipid content in either muscle or subcutaneous fat was not different (P greater than .01) by diet. In lean tissue, palmitic and palmitoleic acids were higher and stearic acid was lower (P less than .01) in rams fed RM than in rams fed RSSBM or SBM, regardless of anatomical location. In the s.c. adipose tissue, the amounts of myristoleic, pentadecylic, and palmitoleic acids were lower and the amount of stearic acid was higher (P less than .01) in rams fed RSSM than in those fed RM or SBM, regardless of anatomical location. The semimembranosus and triceps brachii muscles from all treatments contained 12 to 19% more polyunsaturated fatty acids (PUFA) than the longissimus muscle. The cholesterol content of the three muscles was highest in SBM-fed lambs, lowest in RM-fed lambs, and intermediate in RSSBM-fed lambs. These results demonstrate that dietary treatments of the types used in the present study elicit changes in fatty acid composition of both adipose and muscle tissue without affecting the quantity of total lipid.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of dietary n-6:n-3 fatty acid ratio on feed intake, digestibility, and fatty acid profiles of the ruminal contents, liver, and muscle of growing lambs

This study investigated the effect of modifying the n-6:n-3 fatty acid ratio (FAR) of diets using linseed, soybean, and cottonseed oils on apparent digestibility, ruminal fermentation characteristics, growth performance, key circulating hormones, and the fatty acid profile of ruminal digesta, liver, and fore-shank muscle of growing lambs fed a high concentrate diet. Forty individually housed Katadhin Dorper lambs (average of 20.0 kg of BW) were fed Bermudagrass hay in ad libitum amounts and concentrates at 3.7% of BW daily. The concentrate contained 68.9% corn, 23.8% soybean meal, 3.3% limestone, and 4.0% oil supplements (DM basis). The treatments consisted of dietary n-6:n-3 FAR of 2.3:1, 8.8:1, 12.8:1, and 15.6:1. After feeding for 35 d in metabolism crates, lambs were slaughtered 15 h after feeding, and samples of ruminal digesta, blood, liver, and foreshank tissue were collected. Increasing dietary n-6:n-3 FAR did not affect the intake of DM nor the apparent digestibility of DM, ether extract, NDF, or ADF, but did increase apparent digestibility of CP (linear, P < 0.05). Concentrations of ruminal butyrate increased linearly (P < 0.05) with increasing dietary n-6:n-3 FAR, whereas the valerate concentration decreased linearly (P < 0.001). Concentrations of plasma insulin and IGF-I were not affected by dietary n-6:n-3 FAR. Concentrations of C18:3n-3 increased linearly (P < 0.001), whereas that of C18:2n-6 decreased linearly (P < 0.001) in ruminal digesta with decreasing dietary n-6:n-3 FAR. Concentrations of transisomers of fatty acids in ruminal digesta did not change. Proportions of C18:0 in liver and foreshank muscle were unchanged by diet. The proportion of trans11 C18:1 and cis-9 trans11 CLA decreased (P < 0.05) in liver but increased (P < 0.05) in foreshank muscle as dietary n-6:n-3 FAR decreased. Proportions of all measured n-3 fatty acids were greater in liver when diets contained more C18:3n-3 from linseed oil. By decreasing the dietary n-6:n-3 FAR, the proportions of n-6 fatty acids in foreshank muscle decreased dramatically; specifically, C18:2n-6 decreased linearly (P < 0.001) from 28.0 to 16.5% and C20:4n-6 decreased linearly (P < 0.001) from 14.7 to 8.6%. Although feeding a diet that contained more n-3 fatty acids increased the n-3 fatty acid concentration of muscle, the ratio of PUFA to SFA was decreased.     

日粮n-3多不饱和脂肪酸对母猪繁殖性能的影响

n-3多不饱和脂肪酸作为一种重要的营养物质,能影响家畜繁殖性能。本文主要从n-3多不饱和脂肪酸作用机理、使用效果等方面阐述n-3多不饱和脂肪酸对母猪繁殖性能的影响。     

Effect of dietary modification of muscle long-chain n-3 fatty acid on plasma insulin and lipid metabolites, carcass traits, and fat deposition in lambs

In a previous study we showed that feeding fish meal significantly increased muscle long chain n-3 fatty acids (FA) and hot carcass weight. In this study we compared the effect of fish meal and fish oil on increasing muscle long-chain FA. We also investigated whether the increase in carcass weight was due to the effect of dietary enrichment of muscle long-chain n-3 FA on muscle membrane phospholipids and(or) to rumen by-pass protein provided by fish meal. Forty crossbred ([Merino x Border Leicester] x Poll Dorset) wether lambs between 26 and 33 kg BW were randomly assigned to one of five treatments: 1) basal diet of oaten:lucerne chaff (Basal); 2) Basal + fish meal (9% DM) = FM; 3) Basal + fish oil (1.5% DM) with protected sunflower meal (9% DM ) = FOSMP; 4) Basal + fish oil (1.5% DM) = FO; or 5) Basal + protected sunflower meal (10.5% DM) = SMP. Daily intake of ME (9.60 - 10.5 MJ ME/d) and CP (150 to 168 g/d) in all treatments was kept similar by varying the ratio of oaten:lucerne chaff and by feeding the animals at 90% ad libitum intake. Blood samples were collected at the start of the experiment and on the day (d 42) prior to slaughter. Lambs were then slaughtered at a commercial abattoir. At 24 h postmortem carcass traits were measured and longissimus thoracis muscle taken for analysis of FA of phospholipid and triglyceride fractions. Lambs fed FO and FOSMP showed a marked increase in muscle longchain n-3 FA (P < 0.001) and a reduction in magnitude of the rise in insulin concentration (P < 0.001) after feeding compared with lambs fed Basal and SMP diets. Lambs in FM had a moderate increase (P < 0.001) in muscle long-chain n-3 FA content. Compared with Basal diet, both plasma total cholesterol (P < 0.02) and high-density lipoprotein cholesterol (P < 0.001) levels were greater in SMP and less in FO and FOSMP treatments. The i.m. fat content was reduced (P < 0.05) in FM and FO treatments, but carcass weight was increased only with fish meal (P < 0.03). Adding SMP to FO produced muscle with an intermediate level of i.m. fat, whereas muscle long-chain n-3 FA, i.m. fat, and insulin concentration were unchanged with SMP treatment. These results indicate that an increase in carcass weight in FM may be due to the supply of ruminally undegraded protein. They also suggest that fish oil along with fish meal can increase long-chain n-3 FA content in phospholipid of muscle membrane. This may be associated with reduced i.m. fat content and altered insulin action and lipoprotein metabolism.     

Evaluation of pearl millet and flaxseed effects on egg production and n-3 fatty acid content

1. A 6-week trial was conducted to evaluate the effects of pearl millet (PM) as a replacement for maize, in combination with flaxseed (FS), on productivity, egg trait parameters and egg n-3 fatty acid (FA) content in White Leghorn hens. 2. Six diet treatments were used: a control (CTL, maize-soybean meal based) diet, and diets containing 0, 2, 4, 8 or 12% FS, in which all maize was replaced by PM (PM-0, PM-2, PM-4, PM-8 and PM-12, respectively). All diets were isocaloric and isonitrogenous and met NRC (1994) requirements. Eight cage replicates per treatment were used (three hens per cage). At the end of each week, three eggs were randomly collected from each cage to measure egg trait parameters and yolks were separated, pooled and lyophilised for FA determination. Body weights and feed consumption were recorded weekly. Egg production (number of eggs and egg mass produced) was recorded daily. At the end of the experiment, all hens were killed to determine liver haemorrhage score. 3. Egg traits and flock performance parameters were not different among treatments except at week 4, when birds on the PM-12 diet produced smaller eggs than hens on the PM-0 and PM-2 diets. Yolk pigmentation scores were lower for the PM-0 and PM-2 diets (1.60 +/- 0.24 and 1.80 +/- 0.20, respectively), increased with higher inclusions of FS (2.75 +/- 0.47 for PM-12 diet) but did not reach control levels (6.00 +/- 0.01). Liver haemorrhage scores were not affected by dietary treatment. Hens given the PM-8 and PM-12 diets produced eggs with n-3 FA content higher than required to be considered as n-3 FA enriched eggs, and had a lower n-6/n-3 FA acid ratio than eggs of hens consuming CTL or the PM based diets with lower FS supplementation. 4. These results suggest that PM can be used to substitute for maize in the diets of layers and may reduce the amount of FS needed to obtain n-3 FA enriched eggs.     

Effect of dietary mono- and polyunsaturated fatty acids on the fatty acid composition of pigs' adipose tissues.

In two experiments with growing-finishing pigs six different dietary fats were added to a conventional diet (control--C) to study the effects of dietary monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA) on the fatty acid composition of backfat and kidney fat at similar amounts of double bonds in feed (Exp. 1:7% pork fat--PF, 4.95% olive oil--OO, 3.17% soybean oil--SO) or a constant amount of 5% of processed fats (Exp. 2: partially hydrogenated fat--SAT, fractionated pork fats: olein--OLE, stearin--STE). Compared with the control, PUFA were only slightly increased in backfat of pigs fed PF, OLE, STE or OO, although dietary PUFA intake was up to 70% higher. With SO PUFA were significantly increased in adipose tissues, predominantly at the expense of MUFA. Consequently, a non-linear relationship was found between PUFA intake and proportion in backfat. MUFA were incorporated at the expense of SFA, therefore, adipose tissues of OO fed animals were lowest in SFA. Despite comparable amounts of double bonds in feed (Exp. 1), the degree of unsaturation measured as fat score (sum of double bonds) was in the order SO > OO > PF > C. In contrast, the proportion of SFA was C > PF = SO > OO. Regarding the decisive role of SFA for fat consistency it may be concluded that MUFA should also be considered in feeding recommendations for pigs. Furthermore, in case of a high dietary supply of MUFA, a simple index of double bonds might not be sufficiently conclusive to judge pig fat quality.     

Depot specific endocrine control of fatty acid synthesis in adipose tissues of foetal lambs

Chronic endocrine control of fatty acid synthesis in perirenal and subcutaneous adipose tissues of foetal lambs has been investigated. Maintenance of explants of subcutaneous adipose tissue in culture for 48 hr with insulin and dexamethasone (a glucocorticoid analogue), either singly or in combination showed that the two acted synergistically to increase the rate of fatty acid synthesis. Growth hormone inhibited the ability of insulin plus dexamethasone to increase the rate of fatty acid synthesis in explants of subcutaneous adipose tissue. In contrast neither insulin nor dexamethasone either singly or together increased the rate of fatty acid synthesis in perirenal adipose tissue; growth hormone also had no effect on the rate of fatty acid synthesis in this depot. These studies show that fatty acid synthesis is under distinct endocrine control in subcutaneous and perirenal adipose tissues in foetal lambs.     

Effects of dietary ratio of n-6 to n-3 polyunsaturated fatty acids on immunoglobulins,cytokines, fatty acid composition,and performance of lactating sows and suckling piglets

This experiment was conducted to investigate the effects of dietary ratios of n-6:n-3 polyunsaturated fatty acids (PUFA) on the performance of lactating sows and their piglets. Thirty pregnant Landrace sows were assigned to one of three treatments from d 108 of gestation until weaning (26–29 d) and were fed diets containing different ratios of n-6:n-3 PUFA including 3:1, 9:1 and 13:1. The effects on sow and litter production traits were examined together with an assessment of sow body condition. No differences were detected among the treatments for the daily feed intake of sows or changes in sow weight and back-fat levels during lactation (P > 0.05). Litter size at d 14 and d 21 were tended to increase in 3:1 treatment compared with 9:1 and 13:1 treatments (P < 0.10). Litter weight gain (1.77 kg/d) from d 0 to d 14 was tended to increase in 9:1 groups compared with the other two treatments (P < 0.10). A significant difference was observed for the content of α -linolenic acid, total n-3 PUFA, and the ratio of n-6:n-3 PUFA in the colostrum, milk, and piglets plasma (P < 0.01). The effects of different ratios of n-6:n-3 PUFA in sow diets on colostrum, milk, and piglet plasma immunoglobulin concentrations are studied. No difference was observed among treatments in the concentrations of IgM, and IgA in colostrum (P > 0.05). A great significant difference for IgG concentration was observed among 3 group in colostrum. A great significant difference for IgA, and IgM (P < 0.01) concentrations in piglet plasma at d14 and a significant difference for IgG(P < 0.05) was observed at d14. Furthermore, at d 21 of lactation, piglet plasma IgG and IgA concentration were greater in 3:1 compared with 13:1 group (P < 0.01).In summary, the current study demonstrated that altering the ratio of n-6:n-3 PUFA in lactating sow diet had an effect on the immune component including immunoglobulin and cytokines, and it tended to increase the litter average daily gain and improve the immune status of piglets when dietary ratio of n-6:n-3 PUFA was 9:1.     

Early deposition of n-3 fatty acids from tuna oil in lean and adipose tissue of fattening pigs is mainly permanent

A total of 600 crossbred pigs, whereof 56 were randomly selected for more in-depth studies of carcass and pork quality, were employed to test different tuna oil feeding regimens. The focus was put on the efficiency to enrich lean and adipose tissue with n-3 fatty acids and the expression of adverse side-effects on performance, carcass, and pork quality. The 4 treatments were 0% tuna oil in diet (T0; control), 1% of unrefined tuna oil in diet fed from 35 to 90 kg of BW (T1), and 3% of unrefined tuna oil in diet offered during the early (35 to 60 kg of BW; T3-E) or late stage of fattening (75 to 90 kg of BW; T3-L). With this arrangement, pigs consumed equal lifetime amounts of tuna oil (approximately 1.6 kg per pig). None of the tuna oil treatments had significant effects on performance. There were no differences in carcass quality among tuna oil groups except for group T3-E where carcasses and loin chops were fatter than those of the other groups. Water-holding capacity and texture of the loin as well as firmness and melting properties of the backfat remained widely unaffected by the treatments. Tuna oil feeding resulted in a lighter, less red and less yellow backfat and was found to increase the proportion of n-3 fatty acids to total fatty acids in all treatments. This especially concerned eicosapentaenoic acid and docosahexaenoic acid, but not alpha-linolenic acid. There was also a slight increase in oleic acid, whereas n-6 fatty acids largely decreased. Feeding tuna oil during a short period at the end of fattening (T3-L) or permanently during fattening (T1) proved to be similarly efficient in increasing n-3 fatty acid content of lean and adipose tissue (to about 1.6-fold of T0). By contrast, only two-thirds of this increase was found when the same amount of tuna oil had been fed exclusively during early fattening (T3-E). The decreased efficiency in T3-E was associated with better sensory flavor, overall acceptability grading, and oxidative status. The results show that, particularly under the condition of a continuous supply, much of the n-3 fatty acids ingested in early fattening can be recovered in pork. These findings give farmers flexibility as to when and how pork can be enriched in n-3 fatty acids with fish oil.     

Lipid composition of muscle and adipose tissue from crossbred ram, wether and cryptorchid lambs

Lambs from rams (R), cryptorchids (C) and wethers (W) were examined to compare with the dietary guidelines for humans on fat and cholesterol intake. Twenty-four lambs were assigned to treatments as R, C or W at weaning (60 d). Each lamb had ad libitum access to a 77:23% forage:concentrate diet containing 11.7% crude protein and 1.84 Mcal ME/kg. The experiment was terminated when the lambs reached 50 kg body weight. Lipid composition of the longissimus muscle (LM) and s.c. adipose tissue was determined by gas-liquid chromatography. Rams has less (P less than .01) s.c. fat (cm) and i.m. lipid (%) (.26 cm; 3.*%) than W (.56 cm; 4.9%). Total polyunsaturated fatty acids were greater (P less than .01) in the LM of R (7.06%) than in LM of W (5.21%). Rams had higher percentages of C18:2, C18:3, C20:4 and C18:1 in their LM than W did. On the basis of a 100-g serving of LM, R had 1.73, C had 2.15 and W had 2.21 g saturated fatty acids. There were no (P less than .01) differences among sex types for cholesterol content of LM, which averaged 66.6 mg/100 g wet tissue. The only major difference of the s.c. fat lipid composition was in saturated fatty acids. Wethers had higher (P less than .01) saturated fatty acids (51.4%) than C 46.8%) and R (43.3%). Based on the lipid composition of these three types of lambs, the LM muscle from young R lambs approached dietary fat guidelines for humans more closely than did that from castrates.     

n-3多不饱和脂肪酸强化鸡蛋育鳙鱼苗效果研究

鸡蛋因营养全面均衡,可制成微粒来培育鱼苗,以弥补高密度养殖鱼苗时天然饵料的不足。近20年来,人们愈来愈重视饲料中n-3多不饱和脂肪酸(PUFA)对鱼类的作用,研究开发的n-3PUFA强化鸡蛋是用含有一定量n-3PUFA的原料如鱼油、亚麻籽、红花油等饲喂蛋鸡,经鸡蛋富集而成。目前,该技术     

Effect of a dietary n-6 polyunsaturated fatty acid supplement on distinct immune functions of goats

The aim of this study was to investigate whether dietary n-6 polyunsaturated fatty acids (PUFA) alter immune functions as lymphocyte blastogenesis, expression of lymphocyte and monocyte markers, and cell adhesion molecules of the integrin family in goats. Dutch White castrated male goats received a diet either rich in olive oil (control group, n = 4) or rich in corn oil (test group, n = 4) over a period of 3 weeks. The animals in the test group had significantly higher linoleic acid (LA, 18:2n-6) levels in plasma on days 7, 14 and 21 of the diet than control animals. This was also true for washed erythrocyte membranes at day 21. A significant reduction in the percentage of alpha-4 integrin (CD49d) expressing lymphocytes was observed in goats fed LA rich corn oil at day 21. However, no changes were observed in either lymphocyte proliferative responses to ConA and PHA or the expression of other lymphocyte/monocyte markers. In conclusion, feeding corn oil rich in LA caused significant increases in the proportion of LA in the fatty acid composition of plasma and erythrocyte membranes and was accompanied by a significant decrease of the adhesion molecule alpha-4 integrin (CD49d) on lymphocytes but not on monocytes.     

Effects of breed type and restricted versus ad libitum feeding on fatty acid composition and cholesterol content of muscle and adipose tissue from mature bovine females

Fatty acid composition and cholesterol content of muscle and adipose tissue from mature cows (N = 101) representing 15 breeds and crosses were determined. An initial group of cows was slaughtered after being fed slightly above the maintenance level for 2 wk; the remaining cows were fed either at the maintenance level or ad libitum for 84 d, then slaughtered. Samples of triceps brachii and longissimus muscle and subcutaneous and perinephric adipose tissue were obtained from each carcass. In addition, phospholipid and triacylglycerol fatty acids from total lipid extracts of triceps brachii muscle and subcutaneous adipose tissue were analyzed for 24 cows that were fed ad libitum or at the maintenance level for 84 d. Breed type effects on fatty acid composition were more pronounced in adipose tissue than in muscle tissue. Total lipid extracts of both triceps brachii and longissimus muscle from animals fed a maintenance diet for 84 d contained higher (P less than .01) percentages (3 to 8%) of polyunsaturated fatty acids (PUFA) and lower percentages (2 to 3%) of saturated fatty acids (SFA) than those from animals fed ad libitum for 84 d. This reflected significant variation in the fatty acids C14:0, C16:0, C18:2, C18:3 and C20:4 for both longissimus and triceps brachii muscle. Fatty acid composition within phospholipid and triacylglycerol fractions was similar regardless of maintenance or ad libitum feeding. Much of the variation in total lipid fatty acid composition appeared to be the result of differences in triacylglycerol:phospholipid ratios. Adipose tissue contained about twice as much cholesterol (mg/100 g wet weight) as muscle tissue. Both breed type and feeding group effects on cholesterol content of muscle tissue were nonsignificant. Values for cholesterol content of adipose tissue from cows fed restricted diets were higher than those from cows fed ad libitum (approximately 55 mg/100 g higher for subcutaneous and 25 mg/100 g for perinephric). The results show that changes in fatty acid composition of bovine tissues can be made genetically and by varying the energy level in the diet. Alteration of the cholesterol content of muscle tissue by these methods does not appear to be feasible.     

The scope for manipulating the polyunsaturated fatty acid content of beef: a review

Since 1950, links between intake of saturated fatty acids and heart disease have led to recommendations to limit consumption of saturated fatty acid-rich foods, including beef. Over this time, changes in food consumption patterns in several countries including Canada and the USA have not led to improvements in health. Instead, the incidence of obesity, type II diabetes and associated diseases have reached epidemic proportions owing in part to replacement of dietary fat with refined carbohydrates. Despite the content of saturated fatty acids in beef, it is also rich in heart healthy cis-monounsaturated fatty acids, and can be an important source of long-chain omega-3 (n-3) fatty acids in populations where little or no oily fish is consumed. Beef also contains polyunsaturated fatty acid biohydrogenation products, including vaccenic and rumenic acids, which have been shown to have anticarcinogenic and hypolipidemic properties in cell culture and animal models. Beef can be enriched with these beneficial fatty acids through manipulation of beef cattle diets, which is now more important than ever because of increasing public understanding of the relationships between diet and health. The present review examines recommendations for beef in human diets, the need to recognize the complex nature of beef fat, how cattle diets and management can alter the fatty acid composition of beef, and to what extent content claims are currently possible for beef fatty acids.     

Breed differences and heterosis in triacylglycerol fatty acid composition of bovine adipose tissue

Subcutaneous adipose tissues were biopsied in purebred Jersey (n=17), purebred Limousin (n=17) and reciprocal F₁ Jersey × Limousin crossbred (n=33) calves at the age of 9–10 months. Triacylglycerol fatty acids were extracted and analysed for sex and breed differences. Heterosis, additive and maternal variances were estimated. All calves were pasture‐fed in a single management group and biopsied from the same anatomical site. Heifer calves had significantly higher proportions of palmitoleate, total mono‐unsaturated fatty acids, desaturation index and lower stearate than steer calves. Significant breed differences were observed in that Limousin calves had the highest proportions of palmitate and total saturated fatty acids, whereas Jersey calves had the most palmitoleate and desaturation index. Dominance effects were evident in the proportions of palmitate, stearate, desaturation and elongation enzyme indices due to the observed highly significant heterosis effect. Myristate, palmitate and total saturated fatty acids were considered heritable due to the observed highly significant additive genetic effect.     

The scope for manipulating the polyunsaturated fatty acid content of beef:a review

Since 1950, links between intake of saturated fatty acids and heart disease have led to recommendations to limit consumption of saturated fatty acid-rich foods, including beef. Over this time, changes in food consumption patterns in several countries including Canada and the USA have not led to improvements in health. Instead, the incidence of obesity, type II diabetes and associated diseases have reached epidemic proportions owing in part to replacement of dietary fat with refined carbohydrates. Despite the content of saturated fatty acids in beef, it is also rich in heart healthy cis-monounsaturated fatty acids, and can be an important source of long-chain omega-3(n-3) fatty acids in populations where little or no oily fish is consumed. Beef also contains polyunsaturated fatty acid biohydrogenation products,including vaccenic and rumenic acids, which have been shown to have anticarcinogenic and hypolipidemic properties in cell culture and animal models. Beef can be enriched with these beneficial fatty acids through manipulation of beef cattle diets, which is now more important than ever because of increasing public understanding of the relationships between diet and health. The present review examines recommendations for beef in human diets, the need to recognize the complex nature of beef fat, how cattle diets and management can alter the fatty acid composition of beef, and to what extent content claims are currently possible for beef fatty acids.