包被共轭亚油酸对山羊瘤胃氢化、肠道及乳脂肪酸的影响

文章旨在评估日粮添加棕榈油酸钙和包被共轭亚油酸对瘤胃氢化和长链脂肪酸从十二指肠到乳转化的影响。试验将12只体重(61.9±8.57)kg处于泌乳期的多胎次萨能奶山羊随机分为2组,每组6个重复,每个重复1只羊。两个试验组分别在基础日粮中补充50g棕榈油酸钙和包被共轭亚油酸,试验共开展42d。结果显示,两个试验组对山羊干物质、有机物、中性洗涤纤维、淀粉摄入量及养分在十二指肠流量和瘤胃表观消化率均无显著影响(P>0.05)。与棕榈油酸钙组相比,包被共轭亚油酸组有降低干物质和中性洗涤纤维消化率的趋势(P=0.08),但处理组对淀粉消化率无显著影响(P>0.05)。山羊饲喂棕榈油酸钙或包被共轭亚油酸日粮后,脂肪酸的十二指肠流量高于脂肪酸摄入量。包被共轭亚油酸增加了C18:2trans-10,cis-12和C18:2cis-9,trans-11的十二指肠流量,导致两种脂肪酸对瘤胃的氢化保护率均达到16%。C18:1cis-9、C18:2cis-9,12、C18:3cis-9,12,15的瘤胃生物氢化不受包被共轭亚油酸处理的影响(P>0.05)。综上所述,与添加棕榈油钙相比,在奶山羊中饲喂不受瘤胃生物氢化包被共轭亚油酸对干物质、有机物、中性洗涤纤维、淀粉摄入量、十二指肠流量及瘤胃表观消化率无显著影响。包被共轭亚油酸增加了十二指肠的流量和C18:2trans-10,cis-12和C18:2cis-9,trans-11的比例,使瘤胃生物氢化保护率达到15%~16%。     

Concentration of conjugated linoleic acid in grazing sheep and goat milk fat

The conjugated linoleic acid (CLA) content of grazing sheep and goat milk fat, throughout their lactation period, was examined. Six sheep and six goat representative farms were selected at random and milk samples were taken at monthly intervals for fatty acids profile determination. Sheep and goat nutrition was based on natural grazing and on supplementary feeding during the winter months. From April onwards, grazing native pastures was the only source of feed for sheep and goats. The University farm whose sheep are kept indoors all year round without any grazing, was also used as reference. Fifteen individual milk samples were also taken in April from a sheep and goat farm respectively, in order to see the variability of CLA inside the farm. The results showed that: a. the CLA content of grazing sheep and goat milk fat increased significantly in April–May (early growth stage of grass) and then declined while that of indoors kept sheep was more or less constant during the same period, b. the isomers cis-9, trans-11 and trans-10, cis-12 of CLA were found in grazing sheep milk fat, while in indoors kept sheep and goats' milk fat only the cis-9, trans-11 isomer was found, c. the CLA content of sheep milk fat was much higher than that of goats, d. a negative correlation between sheep milk fat and CLA content was found and e. there was considerable variation in milk fat CLA content between sheep and goat farms and inside the farms.     

The Effect of increasing levels of date palm (Phoenix dactylifera L.) seed on the performance,ruminal fermentation,antioxidant status and milk fatty acid profile of Saanen dairy goats

This study was conducted to examine the effect of date palm (Phoenix dactylifera L.) seed (DPS) on the performance, ruminal fermentation, antioxidant status and milk fatty acid (FA) profile of dairy goats. Eight multiparous Saanen dairy goats, averaging 97 ± 7 days in milk (DIM) and 2150 ± 130 g of milk production, were used in a 4 × 4 replicated Latin square design. Experimental diets contained 0% (control), 6% (DPS6), 12% (DPS12) and 18% (DPS18) of DPS. Dry matter intake (DMI), milk production, and the composition and digestibility of the dry matter (DM), organic matter (OM), neutral detergent fibre (NDF) and crude protein (CP) were not affected by the diets. Adding DPS to the diet increased linearly total antioxidant capacity (TAC) in milk and blood (p < 0.05). No significant difference was found in the malondialdehyde (MDA) content in milk and blood. Superoxide dismutase (SOD) and glutathione peroxidase (GSH‐Px) activities in the blood, ruminal pH, NH₃‐N, ruminal total volatile fatty acid (VFA), acetate, butyrate, isovalerate and valeric acid concentration had no significant effect among the diets. The propionate acid concentration decreased linearly as DPS was added to the diet, and DPS18 had minimum propionate acid concentration (p < 0.05). The inclusion of DPS18 to diets increased linearly the proportion of C18:0 (compared to control) as well as cis‐18:1, trans‐18:1 (compared to control and DPS6) and decreased C14:1 (compared to control) in milk fat (p < 0.05). The concentration of conjugated linoleic acid (CLA) in DPS18 was higher than other diets (p = 0.04). The results of this study implied that replacing DPS with a part of dairy goats’ ration had no negative effects on the performance of the animals and could also improve the antioxidant activity and increase the concentration of CLA in their milk.     

Effect of dietary fish oil on milk yield, fatty acids content and serum metabolic profile in dairy cows

The aim of the study was to evaluate the effects of dietary unprotected fish oil on milk yield, fatty acids content and serum metabolic profile in dairy cows. Forty lactating Polish Holstein-Friesian cows were assigned to two groups. The cows were fed a control basal diet (C group), or a basal diet containing 2% addition of fish oil on mineral carrier (FOM group) during a 8-week period. Supplementing FOM diet of dairy cows had no significant effect on milk fat, milk protein, milk lactose concentration and somatic cells count, but increased the milk yield (36.5 kg/d), (p < 0.05) compared with the control cows (34.28 kg/d). We observed an increase (p < 0.05) in body condition scoring between C and FOM groups. Additionally, higher levels of non-esterified fatty acids and β-hydroxybutyrate acid were noticed in FOM group after 8 weeks of the experiment; however, these serum parameters still were in the reference range. Concentration of insulin was higher (30.40 μU/ml; p < 0.01) in the FOM group compared with the control group (14.03 μU/ml). In the FOM group, significant increase (p < 0.01) in long-chain fatty acids, mainly cis-9, trans-11 CLA and n-3 fatty acids (eicosapentaenoic and docosahexaenoic acids) was observed. The obtained results demonstrated that addition of fish oil to cows' diet could profitably modify the fatty acids in cow's milk.     

Influence of conjugated linoleic acids and vitamin E on milk fatty acid composition and concentrations of vitamin A and α‐tocopherol in blood and milk of dairy cows

The objective of this trial was to investigate the influences of conjugated linoleic acid (CLA ) and vitamin E (Vit. E) and their interactions on fatty acid composition and vitamins in milk (α‐tocopherol, retinol and β‐carotene) as well as on α‐tocopherol in blood of pluriparous cows from week 6 ante partum until week 10 post‐partum (p.p.). We assigned 59 pluriparous German Holstein cows to four treatment groups with the treatment factors CLA and Vit. E at two levels in a 2 × 2 factorial design. Milk fatty acid composition and milk vitamins were analysed on lactation days 7 and 28. α‐tocopherol in blood serum was analysed on days ?42, ?7, 1, 7, 14, 28 and 70 relative to parturition. Milk concentration of α‐tocopherol was influenced by Vit. E (p  < .001) and CLA (p  = .034). Percentage of cis ‐9, trans ‐11 CLA in total milk fat was influenced by treatment with CLA (p  < .001), while for percentage of trans‐ 10, cis ‐12 CLA an interaction between treatment and day (p  = .019), driven by an increase in both CLA groups from day 7 to day 28, was found. Serum ratios of α‐tocopherol to cholesterol were influenced by Vit. E (p  < .001). Results suggest that treatment with CLA during late pregnancy and early lactation is suitable to enhance the proportion of trans‐ 10, cis ‐12 CLA in milk and thereby influencing nutritional properties. As treatment with Vit. E did not have an impact on milk fatty acid composition, it might be possible to increase the antioxidative capacity of the dairy cow without affecting milk properties. Consequently, combined treatment with CLA and Vit. E might elicit synergistic effects on the cow and milk quality by increasing the proportion of CLA in milk fat as well as the excretion of Vit. E and the Vit. E levels in serum.     

Effects of induced subacute ruminal acidosis on milk fat content and milk fatty acid profile

Two lactating dairy cows fitted with a rumen cannula received successively diets containing 0%, 20%, 34% and again 0% of wheat on a dry matter basis. After 5, 10 and 11 days, ruminal pH was measured between 8:00 and 16:00 hours, and milk was analysed for fat content and fatty acid profile. Diets with 20% and 34% wheat induced a marginal and a severe subacute ruminal acidosis respectively. After 11 days, diets with wheat strongly reduced the milk yield and milk fat content, increased the proportions of C8:0 to C13:0 even- or odd-chain fatty acids, C18:2 n-6 and C18:3 n-3 fatty acids but decreased the proportions of C18:0 and cis-9 C18:1 fatty acids. Wheat also increased the proportions of trans-5 to trans-10 C18:1, the latter exhibiting a 10-fold increase with 34% of wheat compared with value during the initial 0% wheat period. There was also an increase of trans-10, cis-12 C18:2 fatty acid and a decrease of trans-11 to trans-16 C18:1 fatty acids. The evolution during adaptation or after return to a 0% wheat diet was rapid for pH but much slower for the fatty acid profile. The mean ruminal pH was closely related to milk fat content, the proportion of odd-chain fatty acids (linear relationship) and the ratio of trans-10 C18:1/trans-11 C18:1 (nonlinear relationship). Such changes in fatty acid profile suggested a possible use for non-invasive diagnosis of subacute ruminal acidosis.     

Effect of supplementation of soy sauce oil and Ca salts of fatty acids on rumen fermentation,milk production and conjugated linoleic acid in milk of dairy cows

Eight cows were used to evaluate the effects of supplementation of soy sauce oil (SO) or Ca salts of fatty acids (FA) on rumen fermentation and milk production. The control diet (CO) consisted mainly of hay, corn silage and a concentrate. In the experimental diets, 400 g/day per cow of SO or FA (soybean oil and rapeseed oil) was supplemented to the CO diet. Experimental period for the three treatments was 14 days, and milk samples were taken during the last 2 days and rumen sample was taken on the last day. Dry matter intake was not affected by the treatments. The number of rumen protozoa at 0 h increased by SO and FA diets. Total volatile fatty acids at 2 h after feeding of SO diet was decreased compared to CO. The milk composition yield did not differ among treatments, although the percentages of fat and protein were decreased by SO and FA diets. The proportions of C8–C16 fatty acids in milk fat decreased, and those of C18 increased by SO and FA diets. The proportion of cis‐9, trans‐11 conjugated linoleic acid in milk fat by SO and FA diets increased by 120% and 135%, respectively. In spite of the slight suppression of rumen fermentation by SO diet, negative effects on feed intake and milk production were not detected.     

Quality and fatty acid profile of the milk of indigenous goats subjected to different local diets in Tunisian arid lands

The study tested the hypothesis that certain pastoral forages and olive by‐products, available in arid areas, may positively influence fatty acid composition and physicochemical properties of goat's milk. Thirty indigenous goats (body weight = 25.2 kg; age = 4.1 years) were allocated to three groups. During 60 days, the goats received ad libitum either dried olive leaves + Stipa tenacissima (group OL), khortane grass hay (group Ko) or oat hay (control diet, group OH). Milk samples were collected and analysed for total solids, fat, protein, lactose and ash content and fatty acid profile. Average milk yield did not statistically differ among groups. Milk total solids from OL group were higher in comparison with Ko and C groups (15.3, 14.7 and 14.5%, respectively; p < 0.05). Fat content was also higher for the OL group as compared to the other groups (5.44 vs. 5.01 and 4.66%, respectively, for Ko and OH). No significant differences were observed for the milk content of lactose, protein and ash. The percentage of saturated fatty acids of total milk fat was higher in OL and Ko groups compared to the C group (p < 0.001); the milk whereof was characterized by the highest percentage of monounsaturated (p < 0.01) and total unsaturated fatty acids. Milk fat of Ko and C groups showed significantly higher proportions of rumenic (CLA cis‐9 trans‐11) and vaccenic acids (C18:1 trans‐11) compared to OL milk. The feeding system based on Stipa tenacissima and dried olive leaves resulted in the milk lowest proportion of trans‐fatty acids and the highest proportion of polyunsaturated ω3‐fatty acids (p < 0.05).     

Effect of dietary fermented fish waste on the digestion of feed and supply of unsaturated fatty acids including conjugated linoleic acid in cattles

Abstract

This study was conducted to evaluate the effect of fermented fish waste (FW) on the digestion of fiber and the flow of unsaturated fatty acids (UFA) to the duodenum and plasma in cattle. Four Holstein cows were used in a 4×4 Latin square design and cows were provided with one of four treatments consisting 0, 5.5, 11, and 16.5% of FW. The digestion of dry matter decreased as the FW increased; however, the lipid concentration increased linearly (P<0.05) as the FW increased. According to the duodenal composition, the lipid concentration and UFA such as conjugated linoleic acid (CLA), arachidonic acid, and docosahexaenoic acid (DHA) increased linearly (P<0.05) as the amount of FW increased in the diet. Additionally, the concentration of CLA, eicosapentaenoic acid and DHA increased linearly (P<0.05) in the plasma as the FW increased. Thus, these findings indicate that FW can be useful as UFA supplementation of feedstuff.     

Effects of pH and fermentative substrate on ruminal metabolism of fatty acids during short‐term in vitro incubation

The ruminal biohydrogenation of c9,c12‐18:2 can be affected by the fibre/starch ratio of the diet and the ruminal pH. The objectives of this study were to examine independently in vitro the effects of fermentation substrate (hay vs. corn starch) and buffer pH (6 vs. 7) on the biohydrogenation of c9,c12‐18:2 carried out by grape seed oil, focusing on its t11 and t10 pathways, using 6‐h ruminal incubations. The experimental design was a 2 × 2 factorial arrangement. Fermentation substrate and pH affected the C18 fatty acid balance in incubated media, but few interactions were observed. Compared with starch, hay as the fermentation substrate favoured the production of 18:0 (×2.3), all trans‐18:1 isomers (×12.6) and CLA (×6.1), except c9,t11‐CLA, and the disappearance of unsaturated C18 fatty acids, but decreased the production of odd and branched chain fatty acids. Compared with pH 6 buffer, pH 7 buffer resulted in higher c9,c12‐18:2 disappearance and CLA production. For c9,t11‐CLA, an interaction was noticed between the two factors, leading to the highest production in cultures incubated on hay with the 7 pH buffer. Compared with starch, hay as fermentation substrate favoured the activity of t11 producers, which are fibrolytic bacteria, and the production of t10 isomers, possibly due to the presence of potential t10 producers in hay. Low pH resulted in a decreased t11 isomers production and in a slightly increased t10 isomers production, probably due to a modulation of enzymatic or bacterial activity.     

Effect of short‐chain fatty acids on triacylglycerol accumulation,lipid droplet formation and lipogenic gene expression in goat mammary epithelial cells

Short‐chain fatty acids (SCFAs) are the major energy sources for ruminants and are known to regulate various physiological functions in other species. However, their roles in ruminant milk fat metabolism are still unclear. In this study, goat mammary gland epithelial cells (GMECs) were treated with 3 mmol/L acetate, propionate or butyrate for 24 h to assess their effects on lipogenesis. Data revealed that the content of triacylglycerol (TAG) and lipid droplet formation were significantly stimulated by propionate and butyrate. The expression of FABP3, SCD1, PPARG, SREBP1, DGAT1, AGPAT6 and ADRP were upregulated by propionate and butyrate treatment. In contrast, the messenger RNA (mRNA) expression of FASN and LXRα was not affected by propionate, but reduced by butyrate. Acetate had no obvious effect on the content of TAG and lipid droplets but increased the mRNA expression of SCD1 and FABP3 in GMECs. Additionally, it was observed that propionate significantly increased the relative content of mono‐unsaturated fatty acids (C18:1 and C16:1) at the expense of decreased saturated fatty acids (C16:0 and C18:0). Butyrate and acetate had no significant effect on fatty acid composition. Overall, the results from this work help enhance our understanding of the regulatory role of SCFAs on goat mammary cell lipid metabolism.     

Effects of dietary supplementation with conjugated linoleic acid on fatty acid composition and lipid oxidation in chicken breast meat

We investigated the effects of dietary conjugated linoleic acid (CLA) on fatty acid composition and lipid oxidation in breast meat of broiler chickens. Broiler chickens (28-day-old females) were fed diets containing experimental oils at 20 g/kg diet for 28 days. The experimental oils consisted of either a 2:0, 1:1, or a 0:2 (wt : wt) ratio of safflower oil (high linoleic acid content) to a commercial CLA mixture. In this study, dietary CLA supplementation significantly increased the composition and content of CLA in chicken meat. The predominant CLA in meat from birds with supplemented diets was the cis -9, trans -11 isomer. The proportion of saturated fatty acid in meat significantly increased with increasing CLA supplementation, with a corresponding decrease in monounsaturated fatty acid. Dietary CLA also reduced thiobarbituric acid reactive substances (TBARS) values in raw meat during storage at 4°C for 5 days. These results provide evidence that CLA feeding is a practical strategy not only for adding nutritional benefits to chicken meat but also for improving meat quality including oxidative stability.     

Pleiotropic effects of the goat prolactin receptor genotype on milk fatty acid composition

In the lactating mammary gland, prolactin (PRL) stimulates the synthesis of lactose as well as fatty acid uptake, lipogenesis, and triacylglycerol synthesis. Associations between bovine PRL receptor (PRLR) genotype and fat yield have been reported, which illustrates the role of PRL in conveying lipids toward the udder as well as in stimulating their local synthesis during lactation. Conversely, and to the best of our knowledge, the effects of PRLR genotype on milk fatty acid content have not been studied so far in any mammalian species. In this study, we sequenced most of the coding region of the caprine PRLR gene in several individuals from the Malagueña and Murciano-Granadina breeds. This approach allowed us to identify 2 long and short mRNA isoforms, produced by alternative splicing, and 4 single-nucleotide polymorphisms (SNPs), namely, c.177T>C, c.1131G>A, c.1201G>A and c.1355C>T. Two of these SNPs are nonsynonymous and involve G401R (c.1201G>A) and T452I (c.1355C>T) amino acid substitutions in the cytoplasmic domain of PRLR, which plays a fundamental role in signal transduction. Performance of an association analysis with milk composition traits in a Murciano-Granadina goat population revealed highly suggestive effects on palmitoleic acid content, whereas suggestive effects were detected for other fatty acids, such as palmitic and linoleic. These results are consistent with the pleiotropic effects of PRL on mammary gland lipid metabolism and milk composition.     

Diet-induced milk fat depression: Association with changes in milk fatty acid composition and fluidity of milk fat

This experiment was designed to examine changes in milk fatty acids during fish oil-induced milk fat depression (MFD) and to test the theory that these changes are related to milk fat fluidity. The experiment was divided into three periods: 1) Baseline: all cows (n = 12) received a high fiber diet without fish oil (FO) for 12 days; 2) Treatment: 4 cows/group received the following treatments for 21 days: a) Low fiber diet without FO (LF), b) High fiber diet + FO (HF + FO) and c) Low fiber diet + FO (LF + FO); 3) Post-treatment: cows returned to the baseline diet and were monitored for 12 days. FO was included at 1.6% DM and HF and LF diets had 40 and 26% NDF, respectively. Milk fat content and yield were unchanged by the LF diet, but were reduced by FO diets at both dietary fiber levels and recovered in the post-treatment period. FO diets caused a pronounced reduction in stearic and oleic acid concentrations in milk fat and an equally pronounced increase in trans-18:1 fatty acid concentrations. Milk fat mean melting point (MMP) was correlated with MFD (r = 0.73) and with milk oleic acid concentration (r = − 0.92). The ratio of oleic:stearic in milk fat increased gradually and consistently in response to FO. Trans-C18:1 isomers with double bounds at carbon ≤ 10 increased with greater MFD and those with double bonds at carbon ≥ 11 decreased with greater MFD. Trans-9 cis-11 CLA explained more than 80% of MFD and was strongly correlated with trans-10 C18:1. Maintenance of MMP below 39–40 °C suggests that the mammary gland was able to secrete only milk fat with adequate fluidity and that MFD could be an adaptation mechanism to prevent secretion of milk with higher MMP.     

The influence of dietary conjugated linoleic acid on blood serum and colostrum immunoglobulin G concentration in female goats before and after parturition

The effects on blood serum and colostrum immunoglobulin G (IgG) levels from including conjugated linoleic acid (CLA) in the diet were evaluated in goats. In experiment 1, 20 goats were allotted into two groups; the CLA group received 20 g/kg of dry matter of CLA 60 and the control group received 0 g/kg of CLA 60, from the third month of gestation until partum. Blood samples were taken every 2 weeks from 1 day before CLA inclusion to partum. From partum until 96 hours, blood and colostrum samples were taken every 24 h. Before partum, IgG serum blood levels were 15.6 and 9.4 mg/ml (CLA and control, respectively); the time effect was statistically significant. After partum (96 h), the effect of CLA dietary inclusion was statistically significant.     

Genotype,production system and sex effects on fatty acid composition of meat from goat kids

Two trials were performed to assess the meat fatty acid profile of goat kids from different genotypes, production systems and sex. In the first trial, genotype effect was determined in 24 suckling male kids from Turkish Saanen, Maltese and Gokceada breeds. In the second trial, male and female Gokceada Goat kids were used to compare the effect of extensive and semi‐intensive production systems on fatty acid composition of meat. Significant genotype effect was observed in the percentages of myristic acid (C14:0), palmitic acid (C16:0), oleic acid (C18:1 n‐9), linolenic acid (C18:3 n‐3), arachidonic acid (C20:4 n‐6) and docosahexaenoic acid (C22:6 n‐3), despite no differences on the ratios of polyunsaturated fatty acids to saturated fatty acids (PUFA/SFA) and n‐6/n‐3 (P > 0.05). The effect of production system had also significant effects on fatty acids, but sex only influenced significantly stearic acid (C18:0), C18:1 n‐9 and C18:3 n‐3 fatty acids and total PUFA level and PUFA/SFA ratio. This study confirms that dairy breeds are prone to produce higher levels of unsaturated fatty acids in their muscle. Meanwhile, meat from Gokceada goat kids, which is one of the indigenous breeds in Turkey, had similar PUFA/SFA and n‐6/n‐3 ratios to Turkish Saanen and Maltase.     

Meat colour,fatty acid profile and carcass characteristics of Hereford bulls finished on grazed pasture or grass silage-based diets with similar concentrate allowance

The objective of this study was to determine the impact of grazed grass (PAS bulls) and grass silage-based (UB bulls) diets on muscle colour, intramuscular fatty acid composition and carcass characteristics of Hereford bulls with similar concentrate allowances, ages, growth rates and carcass weights. The carcass fat score of the UB bulls was 14% higher than that of the PAS bulls (P < 0.05). Muscle lightness was 5%, redness 5% and yellowness 8% higher in the UB bulls than in the PAS bulls (P < 0.05). The Longissimus muscle (LM) of the UB bulls contained a higher proportion of 14:1 and 16:0 fatty acids compared to that of the PAS bulls (P < 0.05). In contrast, the LM of the PAS bulls contained a higher proportion of 18:3n-3 fatty acid and 18:2 cis-9 trans-11 CLA compared to that of the UB bulls (P < 0.01). There were no differences in saturated fatty acid, monounsaturated fatty acid or polyunsaturated fatty acid proportions of the LM muscle between treatments.     

共轭亚油酸在猪生产中的营养重分配作用机理的研究进展

共轭亚油酸(CLA)类似于亚油酸,其有多种异构体,从而具有多种生物学功能。近年来研究发现,在猪生产上CLA在降低体脂含量,促进体蛋白的合成,提高瘦肉率等方面具有重要的营养重分配作用。本文针对CLA的结构组成、营养重分配剂的作用及相关机理的研究作一综述。     

瘤胃保护共轭亚油酸和亚油酸对奶牛产奶性能的影响

选择健康、泌乳月份与产奶量相近的多胎荷斯坦泌乳牛20头,随机分成5组,每组4头,研究日粮中添加商业来源的瘤胃保护共轭亚油酸钙盐(Ca-CLA)同时添加自然来源亚油酸(葵花油)对奶牛生产性能的影响。试验期为52d。对照组基础日粮为60%粗饲料(苜蓿、羊草、青贮)和40%精料(以DM为基础),处理组在对照组日粮基础上分别添加Ca-CLA100g/d·头(CLA)、葵花油350g/d·头(Sunf);Ca-CLA100g/d·头 葵花油350g/d·头(CLA Sunf),Ca-CLA50g/d·头 葵花油175g/d·头(1/2CLA 1/2Sunf)。结果表明:在奶牛日粮中,单独添加自然来源亚油酸产奶量较对照组差异不显著(P>0.05),而单独添加共轭亚油酸钙盐或与自然来源亚油酸高低不同剂量添加产奶量较对照组都分别显著提高2.20%、9.95%、11.16%,无论单独添加自然来源亚油酸或Ca-CLA或二者以高低不同剂量同时添加,牛奶的乳脂率较对照组都分别显著降低15.0%,6.24%,21.74%,14.35%。总之,奶牛日粮中同时添加Ca-CLA和自然来源亚油酸能显著提高产奶量,降低乳脂率,并且,减少Ca-CLA的添加量同时添加自然来源亚油酸可以达到高剂量添加Ca-CLA相同的效果。     

Growth performance,carcass characteristics,fatty acid composition and CLA concentrations of lambs fed diets supplemented with different oil sources

Quality food for human consumption will always be the aim for animal producers. Quantity and composition of fat deposits (fatty acid profile) strongly influences meat quality in ruminants, especially via increasing conjugated linoleic acid (CLA) concentration, which is known to have beneficial anticarcinogenic, antiatherogenic, antidiabetic and cholesterol reduction properties for human health. Awassi lambs are one of the main and most consumed meat sources in the Middle East area; however, studies addressing the fat content of CLA and methods to enhance its concentrations in this breed are still rare. For this reason, the aim of this study was to evaluate the effect of adding two different oil sources (soybean oil (SBO) and sunflower oil (SFO) at two levels (1.8 and 3%)) on growth performance, carcass characteristics and fatty acid profile of fat in Awassi lambs. Oil supplementation had no effect on growth performance or carcass characteristics, while fatty acid composition changed according to the site of extraction. CLA concentrations were increased in the tail fat deposit, with 1.8% SBO and in intermuscular fat deposit with 3% SFO. Intermuscular fat is the one most naturally consumed by humans, serving to improve food quality.