Indoor fattening of lambs raised on pasture. Part 1: Influence of stall finishing duration on lipid classes and fatty acids in the longissimus thoracis muscle

Forty male Ile-de-France lambs (10 blocks of 4 homologous lambs) were used to study the effects of four feeding systems on muscle fatty acids (FA): raising and finishing on cool-season grasses (G), raising on the same grasses and stall-finishing, indoors, on concentrates and hay, respectively, for 22 (GSS) or 41 days (GSL), and stall-feeding indoors on concentrates and hay during both growing and finishing periods (S). Twenty-four lambs only (6 blocks) were retained for comparison of growth performances, lipid content in the longissimus thoracis muscle (LT) and their FA composition according to treatment. The 16 other lambs (4 blocks) were removed from the comparison, due to a large spread in the growth of the lambs towards the end of the trial. No significant effects of treatment were seen on the rate of growth (221, 228, 243 and 245±SE 8.0g/d, respectively, for G, GSS, GSL and S groups), and the lipid contents of the LT (2.22, 2.16, 2.17 and 2.52±SE 0.11g/100g fresh tissue). Grazing, lowered n-6 PUFA (polyunsaturated fatty acids), and increased n-3 PUFA and C18:2 c9t11 (conjugated linoleic acid cis9, trans11) compared to concentrate feeding. The main effects of grazing were not removed by a short period of finish indoors on concentrate (GSS group), but C20:4 n-6 and C22:6 n-3 contents achieved the lowest contents in this group, with significant differences from the values observed for GSL and S groups (C20:4 n-6) or from the three other groups (C22:6 n-3). After a longer period of finish on concentrate (GSL group), C18:3 n-3 (linolenic acid), C18:2 c9t11 and long chain (LC) n-3 PUFA were brought to the levels observed in the S group. In terms of adequacy for human health, the C18:2 n-6/C18:3 n-3 ratios were favourably low in the four groups (2.6, 3.6, 4.9 and 5.2±SE 0.7, respectively, for G, GSS, GSL and S groups), the level observed in the case of G group being significantly lower than for the three other groups and the level observed for GSS group being significantly lower than for the GSL and S groups.     

Effect of grass or concentrate feeding systems and rate of growth on triglyceride and phospholipid and their fatty acids in the M. longissimus thoracis of lambs

Thirty-two male Ile-de-France lambs were used in a factorial 2×2 design to analyse the effects of feeding systems (grass outdoor, G, or concentrate and hay indoor: stall, S) and of growth rate (low, L, or high, H) on total lipids, triglyceride (TG) and phospholipid (PL) contents and their fatty acid composition in the longissimus thoracis muscle (L.T.). Contents were lower for TG (10.4 vs. 15.8 mg/100 g fresh tissue, P<0.05) and higher for PL (6.4 vs. 5.8 mg/100 g fresh tissue, P <0.05) in grass-fed lambs compared to stall-fed ones. TG of grass fed lambs displayed lower proportions of palmitic acid (C16:0), monounsaturated fatty acids (MUFAs), linoleic acid (C18:2n-6) and other (n-6) polyunsaturated fatty acids (PUFA) and higher proportions of stearic acid (C18:0), linolenic acid (C18:3n-3), cis 9, 11 trans C18:2 and trans monounsaturated fatty acids. In PL of the same lambs only lower MUFA, C18:2n-6 and (n-6) PUFA and higher C18:3n-3, (n-3) PUFA and cis 9, 11 trans C18:2 were observed. Growth rate had no effect on lipid, TG or PL contents of longissimus thoracis. However C18:0 proportions were higher in TG and lower in PL for low growth rate lambs. Low growth rate lambs had also lower cis 9, 11 trans C18:2 in TG. Thus, irrespective of growth rate, the muscle lipids characteristic of grass fed lambs fulfilled the recommended features of human food components much better than that of stall fed lambs, namely for CLA and C18:3n-3. The lower ratios of (n-6) to (n-3) PUFA displayed in grass fed lambs both in TG and in PL were also useful to discriminate all the grass fed lambs from all the stall fed animals.     

Influence of ewe feeding systems on fatty acid composition of suckling lambs

The main objective of this study was to evaluate the effects of ewe dietary treatments on the intramuscular fatty acid composition of suckling lambs. Twenty-four pregnant Italian Merino ewes were divided into two equal groups. One group (pasture-fed group) was allowed to graze a natural pasture and the other group (stall-fed group) was penned indoors and fed with hay and concentrate. After lambing, all ewes stayed with their respective lambs for the whole experimental period. Lambs were slaughtered at 100 days of age with an average live weight of 20kg. Fatty acid profiles of milk and lamb meat (longissimus lumborum muscle) were analysed. Intramuscular fat from pasture-fed lambs showed higher (P<0.001) proportions of polyunsaturated fatty acids. The percentage of lauric (C12:0; P<0.05), palmitic (C16.0; P<0.001) and oleic (C18.1; P<0.001) fatty acids were higher in the intramuscular fat from stall-fed lambs, whereas pasture-fed lambs showed greater proportions of linolenic (C18:3; P<0.001), eicosapentaenoic (C20:5; P<0.001) and docosapentaenoic (C22:5; P<0.05) fatty acids. Moreover, the intramuscular fat from pasture-fed lambs displayed a higher (P<0.001) PUFA/SFA ratio, and a lower (p<0.001) n-6/n-3 ratio. The conjugated linoleic acid (CLA) tended to be higher (P=0.07) in the intramuscular fat from pasture-fed lambs. This study confirmed that pasture enhanced the unsaturated fatty acid profile of intramuscular fat in lambs including n-3 fatty acids.     

The effect of spineless cactus (Opuntia ficus-indica f. inermis) supplementation on growth, carcass, meat quality and fatty acid composition of male goat kids

Lambs from two Turkish breeds, Kivircik a meat breed and Sakiz a breed used for milk and meat production, were fed a diet containing commercial concentrate and hay in the ratios of either 75:25 or 25:75. The effects on fatty acid composition were studied. After weaning (at about 8 weeks) a total of 40 male lambs (20 Kivircik, 20 Sakiz) were divided into four groups of 10 animals and fed either commercial concentrate or grass hay-based diets. The lambs were group fed indoors for 60 days. The mean intramuscular total fatty acid content of longissimus dorsi for Sakiz was lower than that for Kivircik lamb. Increasing the dried grass percentage in the ration decreased the final live weight of the lambs but intramuscular total fatty acid content increased (2088 vs. 1791mg/kg muscle, p<0.001). All n-3 polyunsaturated fatty acids were higher in muscle from lamb fed dried grass-based diets than from lambs fed concentrate-based diets whereas all n-6 were higher in the latter. Polyunsaturated:saturated ratios were higher in the latter animals; 0.26 compared with 0.16 in the lambs fed grass hay. Concentrate groups displayed a higher n-6/n-3 ratio in the same muscle, 7.11 compared with 1.28 in the lambs fed grass. Muscle from Kivircik lambs had higher concentrations of C18:2 n-6 and its metabolite C20:4 n-6 (p<0.001) and also C18:3 n-3.     

Influence of stall finishing duration of Italian Merino lambs raised on pasture on intramuscular fatty acid composition

Forty male Italian Merino lambs were used to study the effects of four feeding systems on muscle fatty acids composition: S group-ten lambs were kept indoors, and fed with concentrate for all experimental period (89 days); P group-ten lambs were allowed to graze a pasture for all experimental period; PS37 group-ten lambs were allowed to graze a pasture for 52 days and shifted indoor, fed with concentrate, 37 days before slaughtered; PS14 group, where 10 lambs were fed on pasture for 75 days and shifted indoor, fed with concentrate, 14 days before slaughtered. Grazing lowered the levels of C12:0, C14:0, C16:0 and n-6 PUFA and increased n-3 PUFA and CLA isomer compared to concentrate feeding. After a short period of indoor finishing with concentrate, the fatty acid characteristics of the meat retain a part of the benefits occurring from grazing, while a longer period seems to erase almost all the benefits from grazing.     

Fatty acid composition of lambs of indigenous dairy Greek breeds of sheep as affected by post-weaning nutritional management and weight at slaughter

The objective was to assess the effect of breed, sex, post-weaning nutrition and weight at slaughter on the fatty acids (FA) composition in carcass fat of lambs of indigenous Greek dairy breeds of sheep, the Boutsko (B), Serres (S) and Karagouniko (K) breed. The lambs (weaned at approximately 42 days) had been reared under different conditions of housing and feeding in three consecutive experiments (Experiment). In Experiment 1, lambs (n=120) were individually penned and fed ad libitum on a concentrate feed (11.3MJ metabolisable energy (ME)/kg DM and 192g crude protein (CP)/kg DM) together with 100g/day of Lucerne hay (8.3MJ ME/kg DM and 182g CP/kg DM). In Experiment 2, lambs (n=108) were fed the same concentrate on 3 different levels: High (H), Medium (M) and Low (L) and ad libitum on Lucerne hay. In Experiment 3, lambs (n=108) were initially group fed indoors for 63 days on 3 different levels of concentrate (H, M and L) together with ad libitum Lucerne hay. Thereafter they were finished on irrigated, sown pasture. Lambs were slaughtered at one of 5 standard proportions of mature weight (PMW) for each breed in Experiment 1 (i.e. 0.20, 0.30, 0.45, 0.60 and 0.90); at 3 fixed live weights in Experiment 2 (TSLW; i.e. 23, 28 and 33kg) and at 3 fixed PMW in Experiment 3 (PMW; i.e. 0.20, 0.48 and 0.54). The right hand side of their carcasses was minced and a random sample, around 200g, was taken. It was freeze-dried and then grounded to obtain a quantity of 2g for lipid extraction and preparation of fatty acid methyl esters, which were assayed by gas-liquid chromatography to identify. Results were analysed separately for each experiment by analysis of variance. In Experiment 1, breed of lambs had significant effects (P<0.001) on C14:0, C16:0, C17:0, C18:2, C18:3 and C18:1 (P<0.05), whereas sex affected only the percentage of C15:0, C16:1 (P<0.001), C18:0 (P<0.01) and C18:2 (P<0.05). Live weight of lambs at slaughter had significant effects (P<0.05-0.001) on all the fatty acids. In Experiment 2, with the exception of C18:0 and C20:0, all other fatty acids were significantly affected by Breed (P<0.05-0.001). However, only C17:0, C18:0, C18:1 and C18:2 were significantly (P<0.001) affected by the level of concentrates in the diet. The major finding in Experiment 3 was the trend for saturated fatty acids to be lower; possibly due to the fact that lambs finished at pasture. It is concluded that there are possibilities of modifying FA composition in carcass fat of lambs by manipulation of post-weaning nutrition and slaughtering them at a wide range of live weights.     

The effect of maternal linseed supplementation and/or lamb linseed supplementation on muscle and subcutaneous adipose tissue fatty acid composition of indoor lambs

Eighty eight lambs were used in a 2 × 2 factorial arrangement 1) to investigate the effect of maternal dietary linseed supplementation and/or lamb linseed supplemented concentrate on growth performance, carcass fat quality and fatty acid (FA) composition of muscle and dorsal adipose tissue of indoor lambs 2) to study the relationships between subcutaneous fat quality and FA composition. Feeding linseed to ewes increased C18:3 n-3 (ALA) proportion in milk and therefore the ALA supply to suckling lambs. However, ALA and n-3 polyunsaturated FA (n-3 PUFA) proportions in lamb tissues were not affected. Feeding linseed to lambs during the post-weaning period significantly increased the proportions of ALA and n-3 PUFA in tissues. Softer and more colored fat was associated with a decrease in even medium-chain saturated FA and increases in odd and methyl FA proportions but not with ALA proportion in subcutaneous adipose tissue.     

Effect of feeding on fatty acid composition of muscles and adipose tissues in young goats raised in the Argan tree forest of Morocco

The characteristics of meat from goats raised in the Argan tree forest in the south-western part of Morocco were studied in two experiments. Each experiment was carried out on three groups of six male goats. They were reared either indoors (IC) and fed concentrate or outdoors where they grazed in the Argan tree forest and were offered concentrate (OC) or only Argan fruit pulp (OS). Outdoor-raised goats had a very low growth rate in the first experiment (34 g/d), whereas it was relatively high in the second experiment (64 g/d) in which herbaceous vegetation availability was higher. In each experiment, omental (OM) and perirenal (PR) weights were the lowest in the two groups of goats raised outdoors. Lipid and cholesterol contents in muscles were lower in goats raised in the Argan tree forest than in those raised indoors. Outdoor-raised goats had particularly high proportions of odd-chain fatty acids (FA), branched-chain (FA) of the iso and anteiso series in adipose tissues and muscles and higher n-6 and n-3 polyunsaturated FA (PUFA) proportions and a lower n-6:n-3 PUFA ratio than indoor-raised goats. Indoor-raised goats had a higher proportion of palmitic acid and a lower proportion of archidic acid than outdoor-raised goats. In indoor-raised goats, the proportions of Δ9 straight-chain mono-unsaturated fatty acids (MUFA) (C(16:1n-7) and cis C(18:1n-9)) were relatively higher than those of total MUFA, because of lower percentages of some MUFA, such as C(16:1n-9) and other isomers of oleic acid. The low fat content and FA profile of the meat from the goats reared in the Argan tree forest conveyed beneficial characteristics to this meat in regards to human health. The relatively high contents of branched-chain FA of iso and anteiso series and PUFA in the meat from goats raised in the Argan tree forest could be considered as a sign of typicity.     

Effect of restricted feeding and realimentation periods on pork quality and fatty acid profile of M. longissimus thoracis

An experiment with 94 fattening pigs (48 gilts and 46 barrows) was conducted to determine the effect of feeding 25% restricted diets at different body weights on meat quality and fatty acid profile of M. longissimus thoracis (LT). During the 84 days of the experiment (4 periods, 21 days each), animals with an initial weight of about 31 kg were fed in different periods of observation ad libitum (A) or restricted diets (R) in groups AAAA, AARA, RAAA and RARA. After 21 days of the experiment, the restricted-fed pigs, compared to those fed ad libitum, had a lower total fat content of M. longissimus thoracis (P<0.05), higher shear force (P=0.068), and lower proportions of SFA (C14:0, C18:0 P<0.05) and MUFA and higher proportions of PUFA (C20:4, C22:4 P<0.05) in the fatty acid profile. Three weeks after the restricted feed supply was lifted, the total fat content in LT muscle was higher than in animals fed ad libitum throughout (2.34 vs. 2.02), very close after the next 3 weeks of realimentation (3.16 vs. 3.15) and lower after another 3 weeks (3.19 vs. 3.49). Regardless of the time at which restricted feeding was started and the number of restricted feeding periods, the total fat content in the LT muscle at the end of the experiment was similar or lower in groups RAAA, AARA and RARA, compared to group AAAA. The coefficient of correlation between the total fat content in LT and the shear force was -0.36 (P<0.01). Colour, pH and drip loss did not depend on the level of nutrition. After 84 days of observation, animals from groups RARA and AARA, compared to pigs from groups AAAA and RAAA, were characterized by a slightly higher shear force of LT, lower SFA and MUFA (P<0.001), and higher n-6 PUFA (P<0.01) and n-3 PUFA (P<0.01) proportions in the fatty acid profile. The fatty acid profiles of AAAA pigs and pigs undergoing a 63-day realimentation period (RAAA) were similar. Regardless of the feeding scheme, the n-6:n-3 ratio exceeded 10 in all the groups.     

FATTY ACID COMPOSITION IN TISSUES OF MICE FED DIETS CONTAINING CONJUGATED LINOLENIC ACID AND CONJUGATED LINOLEIC ACID

The influence of 1% alpha-eleostearic acid (α-ESA, cis9,trans11,trans 13-18:3) and 1% punicic acid (PA, cis9,trans11,cis13-18:3) on fatty acid composition in mouse tissues was compared with conjugated linoleic acid (CLA, mixture of primarily cis9,trans11- and trans10,cis12-18:2) in the present study. The content (% total fatty acids) of 18:2n-6 was significantly reduced in the heart and adipose tissues, and total polyunsaturated fatty acids (PUFAs) and n-6 PUFA were significantly reduced in adipose tissue by α-ESA, PA and CLA feeding. The content of 22:6n-3 and total n-3 PUFA were significantly increased in the liver, kidney and heart by PA feeding, but not by α-ESA. In contrast to PA, supplementation with CLA significantly decreased 22:6n-3 in the liver, kidney and heart. The content of 20:4n-6 was significantly decreased in the liver and kidney by CLA feeding, but not by α-ESA and PA. The present results indicate that α-ESA, PA and CLA have differential effects on 22:6n-3 and 20:4n-6 content in mouse tissues.

PRACTICAL APPLICATIONS

Conjugated linolenic acid (CLnA), a group of octadecatrienoic acid isomers with a conjugated triene system, has been reported to exhibit favorable physiological effects, including anticancer properties and regulation of lipid metabolism. Punicic acid and alpha-eleostearic acid, two isomers of CLnA, have been shown to convert into cis 9, trans 11-18:2 in vivo . The effect of CLnA on fatty acid composition in mouse tissues was investigated in comparison with CLA mixtures in the present study. The data obtained here could provide information for the potential application of CLnA-containing seeds as functional food ingredients, a natural source of endogenously formed cis 9, trans 11-18:2 and a dietary feeding strategy to beneficially modify the fatty acid composition of animal tissues.     

Effect of corn silage harvest maturity and concentrate type on milk fatty acid composition of dairy cows

The variation in maturity at harvest during grain filling has a major effect on the carbohydrate composition (starch:NDF ratio) and fatty acid (FA) content of corn silages, and can alter the FA composition of milk fat in dairy cows. This study evaluated the effect of silage corn (cv. Atrium) harvested and ensiled at targeted DM contents of 300, 340, 380, and 420 g/kg of fresh weight and fed to dairy cows in combination with a highly degradable carbohydrate (HC) or low-degradable carbohydrate concentrate, on the nutrient intake, milk yield, and composition of milk and milk fat. Sixty-four multiparous Holstein-Friesian dairy cows in their first week of lactation were assigned to the 8 dietary treatments according to a randomized complete block design. The 8 dietary treatments consisted of a factorial combination of the 4 corn silages and the 2 concentrates. Corn silages were offered ad libitum as part of a basal forage mixture, whereas the concentrates were given at the rate of 8.5 kg of DM/cow per day during the 15-wk experimental period. Dry matter, crude protein, and energy intakes did not differ across the corn silages. However, the intake of starch increased, and those of NDF and C18:3n-3 decreased with increasing maturation. Milk yield and composition were not different across the corn silages. Yield (kg/d) of milk, protein, and lactose was higher for low-degradable carbohydrate compared with HC concentrate-fed groups. Increasing maturity of corn silages decreased the content of C18:3n-3 and total n-3 and increased the n-6:n-3 ratio in milk fat. Concentrate type significantly altered the composition of all trans FA, except C18:2 trans-9,12. Inclusion of the HC concentrate in the diets increased the contents of all C18:1 trans isomers, C18:2 cis-9,trans-11, and C18:2 trans-10,cis-12 conjugated linoleic acid in milk fat. Milk fat composition was strongly influenced by the stage of lactation (wk 3 to 10). The content of all even short- and medium-chain FA changed with lactation, except C8:0 and C10:0. The content of C12:0, C14:0, and C16:0 and total saturated FA increased and the content of C18:0, C18:1 cis total, and total cis monounsaturated FA decreased with lactation. Maturity of the corn silages at harvest did not affect the production performance of dairy cows, but resulted in a decreased content of C18:3n-3, total n-3, and an increased n-6:n-3 ratio in the milk fat of dairy cows.     

Effect of different feeds on meat quality and fatty acid composition of lambs fattened at pasture

Two kinds of feed (commercial concentrate vs whole supplemented barley) were compared in unweaned lambs and lambs weaned at 40 days of age, fattened at pasture and slaughtered at 28 kg live weight, in order to observe their effects on meat quality and fatty acid composition. The weaning status influenced fatness; unweaned lambs displayed a greater carcass fatness score and more kidney knob and channel fat than weaned lambs. Compared with the unweaned animals, weaned lambs exhibited higher pH values at 0 h and 45 min in the m. longissimus thoracis (LT) and at 45 min and 24 h in the m. semitendinosus. The redness index (a*) of the m. LT of weaned lambs was higher than that of unweaned lambs, and lambs fed concentrate displayed a higher yellowness index (b*) and a higher Hue value than those given whole barley. Water-holding capacity did not vary with the treatments studied. The proportion of saturated fatty acids (SFA) in intramuscular fat was higher (P?0.001) in unweaned lambs than in weaned ones while, on the other hand, the latter displayed a higher proportion of monounsaturated fatty acids (MUFA) and a higher n-6/n-3 ratio in the same tissue. As was the case with intramuscular fat, the subcutaneous fat of unweaned lambs exhibited higher proportions of medium-chain fatty acids (C12:0, C14:0 y C16:0) and lower ones of stearic (C18:0) and oleic (C18:1) fatty acids than that of weaned lambs. Higher levels of heptadecenoic acid (C17:1) were found in the subcutaneous fat of lambs fed whole barley than in that of lambs given concentrate. PUFA/SFA and n-6/n-3 ratios were lower in the m. LT than in the m. quadriceps femoris.     

Lamb meat quality as affected by a natural or artificial milk feeding regime

Fourteen Barbaresca lambs were divided into two groups of seven at 24h from birth and reared exclusively on natural milk (NR) or on artificial milk (AR). Lambs were slaughtered at 40 days of age. The NR group tended (P<0.10) to grow faster, thus resulting in a higher (P<0.10) carcass weight as compared to the AR group. AR meat was darker (P<0.05), leaner (P<0.001) and with a higher moisture (P<0.10) and ash (P<0.05) content than its counterpart. The proportion of polyunsaturated fatty acids was higher (P<0.01), while that of saturated lower (P<0.01) in meat from the AR group, resulting in a higher (P<0.01) polyunsaturated/saturated ratio. Linoleic acid content (P<0.001) and its n-6 series derivatives, except 9-12 trans C18:2 n-6 (P<0.001), increased more in the AR group meat than in the NR group. On the other hand, α-linolenic (P<0.001) and other n-3 series fatty acids were higher in meat from the NR group than in the AR group, leading to a lower (P<0.001) n-6/n-3 ratio. Furthermore, 9 cis 11 trans CLA was higher (P<0.001) in NR meat compared to AR meat. Finally, a milk-feeding regime exclusively based on artificial milk adversely affected the dietetic value of lamb meat compared to a natural rearing system, reducing the level of desirable fatty acids such as n-3 series and CLA.     

Changes in fatty acid composition in muscle and adipose tissue of farmed rainbow trout (Oncorhynchus mykiss) in relation to ration and age

To evaluate the importance of age and feed ration level (RL) on the composition of tissue fatty acid (FA) in rainbow trout (Oncorhynchus mykiss), fish were fed rations ranging from appreciable underfeeding to gross overfeeding in a longitudinal experiment lasting from start of feeding to onset of sexual maturation 2.4 years later. In order to study the effects of compensatory growth and reduced feed availability, fish were moved from high to low ration and vice versa. Changes of individual FA of total lipid (TL), triacylglycerols (TAG) and total phospholipids (PL) were studied in white and red muscle, as well as in three major adipose tissues. The effect of saltwater transfer on FA composition was also examined. A strong interdependence was found between the relative proportion of PL and TAG with changes in TL content. This was most prominent in white muscle. In parallel with this change in relative lipid class composition, a major effect was seen on FA in the TL fraction. The most marked effect of RL was an inverse relationship between 22:6 n-3 of the PUFA n-3 series and 16:1 and 18:1 of the MUFA series. This was seen in all tissues studied. It is suggested that the most important factor governing FA composition in muscle, pending changes in feed intake, is the TL content, affecting the relative level of PL and TAG. In adipose tissue, consisting mainly of TAG, more subtle changes were observed. The FA compositions of PL and TAG were not affected to any major extent by RL, except at extreme reductions. Significant changes in FA of PL and TAG were observed as an effect of saltwater transfer.     

Nutritional characteristics of veal from weaned and unweaned calves: Discriminatory ability of the fat profile

The chemical and nutritional composition of the Longissimus thoracis muscle from 58 'Rubia Gallega' breed animals was measured to differentiate veal of weaned from unweaned calves. Fat, protein, ash, and moisture contents of muscle were determined by near infrared reflectance spectroscopy (NIRS) and the fatty acid (FA) profiles were determined by gas chromatography. Calves suckled their mothers at pasture followed by an indoor period. The weaned group was finished on concentrates indoors, whereas the unweaned group was continued suckling with a complementary concentrate diet, also indoors. The unweaned group had higher total FA (p<0.001), monounsaturated (MUFA) (p<0.05) and polyunsaturated (PUFA) (p<0.05) FA contents, lower saturated FA (SFA) (p<0.01) concentration, and a higher PUFA:SFA ratio (p<0.05) than the weaned group. A multivariate step discriminant procedure selected nine variables out of 38 tested from the FA profile. The SFA fraction lower than C11 followed by the margaric FA and the n-6:n-3 PUFA ratio were the most discriminating variables for separating the weaning classes, regardless of the gender. Calibration and cross-validation misclassification errors were 0% and 1.67%, respectively. A more powerful discriminant function was estimated for males only, where the SFA fraction lower than C11 followed by tricosanoic, and margaric FA were the most discriminant, with zero misclassification errors.     

Ruminal fermentation characteristics and fatty acid profile of ruminal fluid and milk of dairy cows fed flaxseed hulls supplemented with monensin

Flaxseed hull, a co-product obtained from flax processing, is a rich source of n-3 fatty acids (FA) but there is little information on its value for dairy production. Monensin supplementation is known to modify biohydrogenation of FA by rumen microbes. Therefore, the main objective of the experiment was to determine the effect of feeding a combination of monensin and flaxseed hulls on ruminal fermentation characteristics and FA profile of ruminal fluid and milk. Four ruminally fistulated multiparous Holstein cows averaging 665 ± 21 kg body weight and 190 ± 5 d in milk were assigned to a 4×4 Latin square design (28-d experimental periods) with a 2×2 factorial arrangement of treatments. Treatments were: 1) control, neither flaxseed hulls nor monensin; 2) diet containing (dry matter basis) 19·8% flaxseed hulls; 3) diet with monensin (16 mg/kg dry matter); 4) diet containing 19·8% (dry matter basis) flaxseed hulls and 16 mg monensin/kg. Flaxseed hull supplementation decreased the acetate to propionate ratio in ruminal fluid and monensin had no effect. Concentrations of trans-18:1 isomers (trans9,trans11,trans13/14+6/8) and cis9,12,15-18:3 in ruminal fluid and milk fat were higher and those of cis9,12-18:2 in milk fat tended (P=0·07) to be higher for cows supplemented with flaxseed hulls than for cows fed no flaxseed hulls. Monensin had little effect on milk fatty acid profile. A combination of flaxseed hulls and monensin did not result in better milk fatty acid profile than when feeding only flaxseed hulls.     

Comparison of the color stability and lipid oxidative stability of fresh and vacuum packaged lamb muscle containing elevated omega-3 and omega-6 fatty acid levels from dietary manipulation

A series of three experiments were conducted with second cross ([Merino×Border Leicester]×Poll Dorset) wether lambs to evaluate the effects of dietary treatments on manipulation of muscle long-chain (LC) omega-3 fatty acids (FA) on the color stability and oxidative stability of fresh and vacuum packaged lamb. At the end of 7-, 6- and 6-week experimental periods for experiments (Exp.) 1-3 respectively, lambs were slaughtered at a commercial abattoir. At 24 h post-mortem, muscle longissimus lumborum (LL) and longissimus thoracis (LT) were removed and evaluated for color and lipid oxidative stability under specified commercial storage and display condition. Of the dietary supplements used, fish meal and fish oil moderately (P<0.01) and markedly (P<0.001) increased muscle omega-3 FA content, while both protected canola seed (P<0.001) and protected sunflower meal protein significantly (P<0.02) increased muscle omega-6 FA content or ratio of omega-6/omega-3 of the longissimus muscle. In all experiments, the substantial increase (P<0.001) in muscle LC omega-3 and omega-6 FA had no consistent significant effect on color values (redness (a*), yellowness (b*) and lightness (L*)) for fresh and vacuum packaged lamb over a 6-day display period. Lipid oxidation, determined by the levels of thiobarbituric acid reactive substances (TBARS) indicated the enrichment of muscle polyunsaturated fatty acid (PUFA) levels in lambs did not produce significant differences resulting either from main treatment effects or for treatment×day×type interactions (where type was fresh and vacuum packaged). Present results demonstrated the color and lipid oxidative stability of lamb longissimus muscle during refrigerated display was not affected by enhanced levels of omega-3 and omega-6 FA due to dietary treatments.     

Effect of weaning status on lipids of Galician Blond veal: Total fatty acids and 18:1 cis and trans isomers

The effect of weaning at different ages (NW = not weaned, W5 = 5.5 months and W2 = 2 months) on fatty acids (FA) of the Longissimus thoracis (LT) muscle was studied in 36 Galician Blond (GB) calves. Total FA (TFA) were determined by gas chromatography (GC) and 18:1 isomers by a combination of reversed-phase high performance liquid chromatography (HPLC) and GC. NW group showed higher (P < 0.001) values of n-3 polyunsaturated FA (PUFA), conjugated linoleic acid (CLA) and 18:1trans-11 compared to LT from W5 and W2 calves. W2 calves showed the highest levels of n-6 PUFA (P < 0.01), 18:1trans-10 and 18:1trans-6/7/8 (P < 0.001). Generally, W5 calves had intermediate values for TFA and 18:1 isomers. As the suckling period was longer, GB milk and veal FA profiles became more similar, it seems that muscle FA were partially transmitted by the milk FA intake due to the persistence of the reticular grove closing reflex.     

Effect of pasture finishing on the meat characteristics and intramuscular fatty acid profile of steers of the Rubia Gallega breed

The Rubia Gallega cattle breed is the most important stock for beef production in Spain. A study about the influence of feeding systems on beef quality is needed. Comparison of the effect of a pasture finishing system and an indoors finishing system (maize silage and concentrate) on the meat quality and intramuscular fatty acid profile of Rubia Gallega steers (slaughter age 30 months) was determined using samples of Longissimus thoracis muscle. There were no differences between treatments in meat pH, drip loss, water holding capacity, cooking loss and muscle colour. Meat from pasture-fed steers was more tender than meat from indoors finished ones at 24 h post-mortem, but differences disappeared at 7 days. Subcutaneous fat of grass-fed steers showed higher yellowness at 24 h and 7 days post-mortem and lower brightness at 7 days post-mortem than indoors finished ones. Intramuscular fat of indoors finished steers presented higher concentrations of C18:2 and a less favourable ratio of n-6/n-3 polyunsaturated fatty acids than pasture finished steers.     

Fatty acid composition of M. Longissimus dorsi from Holstein-Friesian steers of New Zealand and European/American descent and from Belgian Blue×Holstein-Friesian steers, slaughtered at two weights/ages

Our objective was to determine the effect of breed (B) and slaughter age/weight on the fatty acid composition, particularly the conjugated linoleic acid (CLA) concentration of beef. Two strains of a dairy breed [Holstein-Friesian (HF) (n=16 steers/strain)] and a late-maturing breed [Belgian Blue×Holstein-Friesian (BB) (n=16 steers)] were used. The HF strains were either of New Zealand (NZ) or European-American (EU) descent (selected in a grazed grass or a high concentrate nutritional environment, respectively). Animals were grown from calves to either a light (L; 560kg) or heavy (H; 630kg) target slaughter weight. Samples of M. longissimus dorsi were collected post-slaughter, lipids were separated into neutral (NL) and polar (PL) fractions, and fatty acid composition determined by gas-chromatography. The total fatty acid concentration and the concentrations of cis9, trans11 CLA, total CLA, MUFA and SFA in total intramuscular lipids were lower and the P:S ratio higher for BB than NZ or EU which did not differ. These differences largely reflected the changes in NL. The C18 desaturase index was higher for NZ than EU but EU did not differ from BB. Increasing slaughter weight/age increased the total fatty acid concentration and the concentrations cis9, trans11 CLA (P=0.06), total CLA (P=0.06), trans11 C18:1, MUFA and SFA and the C18 desaturase index and decreased the P:S ratio. The n-6:n-3 PUFA ratio was similar at the lighter slaughter weight/age for the three breeds/strains but increased for NZ and EU with increasing slaughter weight/age but was not affected in BB. It is concluded that the CLA concentration largely reflected muscle fatness but that increasing slaughter weight/age differentially affected the n-6:n-3 PUFA ratio of beef from early and late-maturing cattle.