51
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Doreau M, Rearte D, Portelli J, Peyraud JL. Fatty acid ruminal metabolism and digestibility in cows fed perennial ryegrass. EUR J LIPID SCI TECH 2007. [DOI: 10.1002/ejlt.200700003] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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52
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Fatty acids and tocopherol levels in M. Longissimus dorsi of beef cattle in Sweden – A comparison between seasonal diets. Meat Sci 2007; 76:746-54. [DOI: 10.1016/j.meatsci.2007.02.021] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2006] [Revised: 02/19/2007] [Accepted: 02/19/2007] [Indexed: 11/23/2022]
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53
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Effect of grazing pastures of different botanical composition on antioxidant enzyme activities and oxidative stability of lamb meat. Meat Sci 2007; 75:737-45. [DOI: 10.1016/j.meatsci.2006.10.010] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2006] [Revised: 10/02/2006] [Accepted: 10/06/2006] [Indexed: 11/22/2022]
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54
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Lee MRF, Tweed JKS, Moloney AP, Scollan ND. The effects of fish oil supplementation on rumen metabolism and the biohydrogenation of unsaturated fatty acids in beef steers given diets containing sunflower oil. ACTA ACUST UNITED AC 2007. [DOI: 10.1079/asc41920361] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
AbstractDuodenally and ruminally fistulated steers were offered grass silage and one of three concentrates at a ratio of 60: 40 (forage: concentrate on a dry-matter basis) : F0, F1 or F4 at 14 g/kg live weight. The concentrates were designed to be iso-lipid and to provide the same amount of sunflower oil but increasing amounts of fish oil : 0, 1 and 4 g per 100 g, respectively. Ruminal characteristics were measured along with fatty acid intakes and duodenal flows to determine the effect of fish oil on : ruminal pH, ammonia-N concentration, volatile fatty acid (VFA) concentration and polyunsaturated fatty acid (PUFA) metabolism. Fish oil had no significant effect on ruminal pH, ammonia-N concentration or the molar proportions of the major VFA, although total VFA concentration was significantly reduced at the highest level of fish oil inclusion. Fish oil significantly increased the flow of long chain PUFA, total conjugated linoleic acid and vaccenic acid to the duodenum and decreased the flow of stearic acid. Biohydrogenation, as determined by the net loss of fatty acid between the mouth and duodenum, of oleic and linolenic acid was not affected by fish oil inclusion and averaged 0·64 and 0·92, respectively. There was a small increase in the biohydrogenation of linoleic acid with increasing fish oil from 0·89 to 0·92 (P< 0·01) on F0 and F4, respectively. Biohydrogenation of the long chain PUFA C20 : 5(n-3) and C22 : 6(n-3) increased from 0·49 and 0·74 to 0·79 and 0·86 (P< 0·01), respectively when fish oil in the concentrate increased from 1 to 4 g per 100 g. The net effect of fish oil on lipid metabolism appears to inhibit the transition of vaccenic acid to stearic acid in the rumen resulting in a build up of this intermediate in the biohydrogenation pathway of C18 PUFA.
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55
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Lee MRF, Tweed JKS, Dewhurst RJ, Scollan ND. Effect of forage: concentrate ratio on ruminal metabolism and duodenal flow of fatty acids in beef steers. ACTA ACUST UNITED AC 2007. [DOI: 10.1079/asc20058] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
AbstractThe objective of this study was to determine the proportion of forage in the diet which would maximize duodenal flow of unsaturated fatty acids in beef steers supplemented with linseed oil. A second objective was to determine how diets differing in forage content, but equal in nitrogen (N), energy and lipid supply, would affect the duodenal flow of C18:1and conjugated linoleic acid (CLA) isomers. Eight Hereford×Friesian steers (533±13·6 kg), prepared with rumen and duodenal cannulae were offered one of four forage:concentrate (F:C) ratios: F80C20; F60C40; F40C60 and F20C80 on a dry-matter (DM) basis. All diets were offered at 0·013 body weight and designed to be isonitrogenous and isoenergetic with total lipid made up to 0·06 DM intake with linseed oil. The experimental design was a replicated incomplete 4×4 Latin square with three periods. Increasing the concentrate component in the diet from 0·20 to 0·60 reduced rumen pH from 6·58 to 6·37 and caused a small but significant shift in volatile fatty acid molar proportions, decreasing the non-glucogenic ratio. Rumen ammonia-nitrogen concentration was also significantly reduced with increasing concentrate, from 156·8 to 101·0 mg N per l on F80C20 and F20C80, respectively. Microbial nitrogen (MN) and the efficiency of microbial protein synthesis was significantly elevated as forage level decreased from 51·6 to 72·4 g/day and 17·2 to 27·3 g MN per kg organic matter apparently digested in the rumen, respectively for F80C20 and F20C80. Intake and duodenal flow of C18:1n-9 and C18:2n-6 were significantly higher with increasing concentrate level in the diet whereas C18:3n-3 intake and flow was not different, averaging 143·6 and 6·37 g/day, respectively. There were no differences in the flows of total C18:1transor CLA (47·7 and 1·79 g/day, respectively) across the diets. However, although not significantly different in duodenal flow there were trends (P<0·1) for an increasing proportion of trans-10 and a decreasing proportion oftrans-11 when increasing the concentrate in the diet. Biohydrogenation of C18:2n-6 decreased from 0·91 to 0·85 when increasing concentrate in the diet from 0·20 to 0·40 but further increases had no effect. F:C ratio had little effect on the flow of unsaturated fatty acids, C18:1transand CLA to the duodenum of beef steers, and this may relate to the ability of the rumen to buffer the large changes in concentrate intake.
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56
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Broderick GA, Brito AF, Olmos Colmenero JJ. Effects of Feeding Formate-Treated Alfalfa Silage or Red Clover Silage on the Production of Lactating Dairy Cows. J Dairy Sci 2007; 90:1378-91. [PMID: 17297112 DOI: 10.3168/jds.s0022-0302(07)71624-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
In trial 1, 15 Holsteins were fed 3 total mixed rations (TMR) with 33% neutral detergent fiber in 3 x 3 Latin squares (28-d periods). Two TMR contained (dry matter basis): 40% control alfalfa silage (CAS) or 40% ammonium tetraformate-treated alfalfa silage (TAS), 20% corn silage (CS), 33% high-moisture shelled corn (HMSC), 6% solvent soybean meal (SSBM), and 18% crude protein (CP); the third TMR contained 54% red clover silage (RCS), 6% dried molasses, 33% HMSC, 6% SSBM, and 16.3% CP. Silages differed in nonprotein N (NPN) and acid detergent insoluble N (ADIN; % of total N): 50 and 4% (CAS); 45 and 3% (TAS); 27 and 8% (RCS). Replacing CAS with TAS increased intake, yields of milk, fat-corrected milk, protein, and solids-not-fat, and apparent dry matter and N efficiency. Replacing CAS with RCS increased intake and N efficiency but not milk yield. Replacing CAS or TAS with RCS lowered milk urea N, increased apparent nutrient digestibility, and diverted N excretion from urine to feces. In trial 2, 24 Holsteins (8 ruminally cannulated) were fed 4 TMR in 4 x 4 Latin squares (28-d periods). Diets included the CAS, TAS, and RCS (RCS1) fed in trial 1 plus an immature RCS (RCS2; 29% NPN, 4% ADIN). The CAS, TAS, and RCS2 diets contained 36% HMSC and 3% SSBM and the RCS1 diet contained 31% HMSC and 9% SSBM. All TMR had 50% legume silage, 10% CS, 27% neutral detergent fiber, and 17 to 18% CP. Little difference was observed between cows fed CAS and TAS. Intakes of DM and yields of milk, fat-corrected milk, fat, protein, lactose, and solids-not-fat, and milk fat and protein content were greater on alfalfa silage vs. RCS. Blood urea N, milk urea N, ruminal ammonia, and total urinary N excretion were reduced on RCS, suggesting better N utilization on the lower NPN silage. Apparent N efficiency tended to be higher for cows fed RCS but there was no difference when N efficiency was expressed as kilograms of milk yield per kilogram of total N excreted.
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Affiliation(s)
- G A Broderick
- Agricultural Research Service, USDA US Dairy Forage Research Center, 1925 Linden Drive West, Madison 53706, USA.
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57
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Effect of botanical composition of silages on rumen fatty acid metabolism and fatty acid composition in longissimus muscle and subcutaneous fat of lambs. Animal 2007; 1:911-21. [DOI: 10.1017/s1751731107000316] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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58
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Effect of grazing pastures with different botanical composition by lambs on rumen fatty acid metabolism and fatty acid pattern of longissimus muscle and subcutaneous fat. Animal 2007; 1:537-45. [DOI: 10.1017/s1751731107703531] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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59
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60
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Dewhurst R, Shingfield K, Lee M, Scollan N. Increasing the concentrations of beneficial polyunsaturated fatty acids in milk produced by dairy cows in high-forage systems. Anim Feed Sci Technol 2006. [DOI: 10.1016/j.anifeedsci.2006.04.016] [Citation(s) in RCA: 269] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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61
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Lee MRF, Connelly PL, Tweed JKS, Dewhurst RJ, Merry RJ, Scollan ND. Effects of high-sugar ryegrass silage and mixtures with red clover silage on ruminant digestion. 2. Lipids1. J Anim Sci 2006; 84:3061-70. [PMID: 17032800 DOI: 10.2527/jas.2005-736] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The experiment investigated the digestion of lipids from different forage silages in beef steers. Six Hereford x Friesian steers prepared with rumen and duodenal cannulas were given ad libitum access to a high-sugar grass silage, control grass silage, red clover silage, or mixtures of the red clover and each of the grass silages (50:50, DM basis). The experiment was conducted as an incomplete 5 x 5 Latin square, with an additional randomly repeated sequence. Total fatty acid and C18:3n-3 concentrations were greater (P < 0.05) for the high-sugar grass silage than the control grass silage or the red clover silage. Dry matter and total fatty acid intake were less (P < 0.05) for steers fed the control grass silage than for steers fed the other diets. Duodenal flow of C18:3n-3 was greater (P < 0.05), and flows of C18:0 and total C18:1 trans were less (P < 0.05), for the red clover silage compared with the 2 grass silage diets, with the mixtures intermediate. These results were supported by a reduction (P < 0.05) in biohydrogenation of C18:3n-3 for the red clover silage, with the mixtures again being intermediate. Flows of total branched- and odd-chain fatty acids were greater (P < 0.05) for the high-sugar grass silage diet, possibly as a result of greater microbial flow, because these fatty acids are associated with bacterial lipid. Duodenal flows of the chlorophyll metabolite, phytanic acid, were greater (P < 0.05) for animals fed the high-sugar grass silage treatments compared with the other treatments. These results confirm the potential for modifying the fatty acid composition of ruminant products by feeding red clover silage.
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Affiliation(s)
- M R F Lee
- Institute of Grassland and Environmental Research, Plas Gogerddan, Aberystwyth, SY23 3EB, UK.
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62
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Merry RJ, Lee MRF, Davies DR, Dewhurst RJ, Moorby JM, Scollan ND, Theodorou MK. Effects of high-sugar ryegrass silage and mixtures with red clover silage on ruminant digestion. 1. In vitro and in vivo studies of nitrogen utilization1. J Anim Sci 2006; 84:3049-60. [PMID: 17032799 DOI: 10.2527/jas.2005-735] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Two experiments were carried out to determine the effects of feeding grass silages differing in their water-soluble carbohydrate content, with or without red clover silage, on the efficiency of nutrient use. High-sugar grass, control grass, and red clover were ensiled in laboratory silos for use in an in vitro experiment (Exp. 1). For an in vivo experiment (Exp. 2), the same forage types were baled and ensiled. All silages were well preserved; within experiments the grass silages had similar composition, except for greater (P < 0.05) water-soluble carbohydrate concentrations in the high-sugar than the control grass silage. In Exp. 1, high-sugar grass, control grass, and red clover silages were fed alone or as mixtures (30:70, 50:50, or 70:30 on a DM basis, respectively) of each grass with the red clover silage to a simulated rumen culture system. There were no significant differences in microbial N flow or efficiency of microbial protein synthesis between individual forages. However, the corresponding values for the 70:30 ratio of high-sugar grass:red clover silage were greater (P < 0.05) than for the red clover silage. The value for the efficiency of N use (g of microbial N/g of feed N) was greater (0.86; P < 0.05) for high-sugar grass silage than the control grass silage. In addition, the high-sugar grass:red clover silage mixtures all gave greater (P < 0.05) values for the efficiency of N use than red clover silage alone; this difference was not achieved with the control grass mixture. Experiment 2 was an incomplete Latin square design conducted with 6 Here-ford x Friesian steers (163 +/- 5.9 kg of BW) with rumen and duodenal cannulas fed the following 5 silage diets: high-sugar grass silage; control grass silage; high-sugar grass and red clover silage (50:50 DM basis); control grass and red clover silage (50:50 DM basis); and red clover silage. Rumen NH3-N concentration was lowest (P < 0.05) with the high-sugar grass silage. Microbial N flows to the duodenum and efficiency of microbial protein synthesis were greater (P < 0.05) for steers fed the high-sugar grass silage than for control grass and red clover silages, and mixing red clover with grass silages increased (P < 0.05) these values compared with red clover silage alone. In both experiments, the efficiency of incorporation of silage N into microbial N was more than 20% greater (P < 0.05) for high-sugar grass than for control grass silage. These data suggest that grass silage with high-sugar content provides a forage-based strategy for balancing N and energy supply and improving the efficiency of use of grass silage N in the rumen.
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Affiliation(s)
- R J Merry
- Institute of Grassland and Environmental Research, Plas Gogerddan, Aberystwyth, SY23 3EB, UK
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63
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Givens D, Kliem KE, Gibbs RA. The role of meat as a source of n−3 polyunsaturated fatty acids in the human diet. Meat Sci 2006; 74:209-18. [DOI: 10.1016/j.meatsci.2006.04.008] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2006] [Revised: 04/05/2006] [Accepted: 04/11/2006] [Indexed: 10/24/2022]
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64
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Ribeiro CVDM, Karnati SKR, Eastridge ML. Biohydrogenation of fatty acids and digestibility of fresh alfalfa or alfalfa hay plus sucrose in continuous culture. J Dairy Sci 2006; 88:4007-17. [PMID: 16230707 DOI: 10.3168/jds.s0022-0302(05)73087-3] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The pattern of biohydrogenation of fatty acids from fresh alfalfa or alfalfa hay supplemented with 3 concentrations (0, 4, and 8%) of sucrose was studied at a constant pH of 6.2. Four continuous culture fermenters were used in a 4 x 4 Latin square design to test the hypothesis that fresh forage would increase flow of vaccenic acid (VA) from the fermenters compared with the same forage in hay form and that this difference would be diminished by adding sucrose to the hay diet by changing the bacterial community profile. Effluent was collected from each of the 4 fermenters during the last 3 d of each 10-d period. Nutrient digestibility, volatile fatty acids (VFA), and fatty acids in the effluent were measured. Flow of bacterial organic matter (OM) and neutral and acid detergent fiber and acid detergent fiber digestibilities were higher for fresh alfalfa than alfalfa hay. True OM digestibility of alfalfa hay tended to linearly decrease with sucrose supplementation. However, microbial efficiency and flow of bacterial OM (g/d) linearly increased with sucrose addition. There was no change in total VFA concentration; however, proportion of acetate linearly decreased and proportion of butyrate linearly increased with sucrose addition. Fresh alfalfa increased total biohydrogenation of fatty acids compared with than hay. Vaccenic acid flow (mg/d) was much higher for fresh alfalfa compared with alfalfa hay (216 vs. 41) and VA was the predominant 18:1 isomer, followed by trans-13 18:1; however, sucrose had no effect on VA flow. The percentage of VA (of total trans-18:1) was not different between fresh alfalfa and hay, whereas percentage of trans-10 18:1 was much lower for fresh alfalfa. Therefore, the ratio of VA to trans-10 18:1 was higher for fresh alfalfa. Flow of trans-12 18:1 linearly increased, whereas flows of cis-12 and total cis-18:1 had quadratic responses to sucrose supplementation. Total biohydrogenation and biohydrogenation of linoleic and linolenic acids linearly decreased with sucrose; however, there was no effect of sucrose on total trans fatty acid flow. Sucrose may be more detrimental to the last step of biohydrogenation of VA. The effects of sucrose on biohydrogenation and concentration of VFA may have been caused by a shift in microbial population by mechanisms that are independent of pH.
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Affiliation(s)
- C V D M Ribeiro
- Department of Animal Sciences, The Ohio State University, Columbus 43210, USA
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65
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Loor J, Ueda K, Ferlay A, Chilliard Y, Doreau M. Intestinal flow and digestibility of trans fatty acids and conjugated linoleic acids (CLA) in dairy cows fed a high-concentrate diet supplemented with fish oil, linseed oil, or sunflower oil. Anim Feed Sci Technol 2005. [DOI: 10.1016/j.anifeedsci.2005.01.001] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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66
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Palmquist DL, Lock AL, Shingfield KJ, Bauman DE. Biosynthesis of conjugated linoleic acid in ruminants and humans. ADVANCES IN FOOD AND NUTRITION RESEARCH 2005; 50:179-217. [PMID: 16263431 DOI: 10.1016/s1043-4526(05)50006-8] [Citation(s) in RCA: 170] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Affiliation(s)
- Donald L Palmquist
- Department of Animal Sciences, Ohio Agricultural Research and Development Center/The Ohio State University, Wooster, Ohio 44691, USA
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67
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Dewhurst RJ, Scollan ND, Lee MRF, Ougham HJ, Humphreys MO. Forage breeding and management to increase the beneficial fatty acid content of ruminant products. Proc Nutr Soc 2004; 62:329-36. [PMID: 14506880 DOI: 10.1079/pns2003241] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The declining consumption of ruminant products has been partly associated with their high proportion (but not necessarily content) of saturated fatty acids. Recent studies have focused on the less prominent fact that they are also important sources of beneficial fatty acids, including n-3 fatty acids and conjugated linoleic acids. alpha-Linolenic acid (18 : 3n-3) is of particular interest because it also contributes to improved flavour of beef and lamb. Many recent studies showed large effects of special concentrates on levels of fatty acids in milk and meat. However, the 'rumen protection' treatments, needed to ensure a worthwhile level of fatty acid in products, are expensive. Herbage lipids are the cheapest and safest source of these fatty acids and so breeding to increase delivery of fatty acids from plants into ruminant products is an important long-term strategy. Plant lipids usually contain high levels of polyunsaturated fatty acids, particularly 18 : 2n-6 and 18 : 3n-3 which are the precursors of beneficial fatty acids. Whilst some plants are particularly rich in individual fatty acids (e.g. 18 : 3n-3 in linseed), there are also useful levels in grass and clover (Trifolium Spp.). Levels of fatty acids in forages in relation to species and varieties are considered, as well as management and conservation methods. Relationships between levels of fatty acids and existing traits and genetic markers are identified. The effects of forage treatments on the fatty acid content of ruminant products are reviewed. The higher levels of polyunsaturated fatty acids in milk from cows fed clover silages show that the level of fatty acids in herbage is not the only factor affecting levels of fatty acids in ruminant products. Further effort is needed to characterise susceptibility of unsaturated fatty acids to oxidative loss during field wilting and biohydrogenation losses in the rumen, and the relative importance of plant and microbial processes in these losses. The pathways of lipolysis and lipid oxidation are reviewed and other plant factors which offer potential to breed for reduced losses are considered.
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Affiliation(s)
- R J Dewhurst
- Institute of Grassland and Environmental Research, Plas Gogerddan, Aberystwyth SY23 3EB, UK.
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68
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Al-Mabruk RM, Beck NFG, Dewhurst RJ. Effects of Silage Species and Supplemental Vitamin E on the Oxidative Stability of Milk. J Dairy Sci 2004; 87:406-12. [PMID: 14762084 DOI: 10.3168/jds.s0022-0302(04)73180-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Two experiments were conducted to study the effects of feeding legume silages and providing supplemental vitamin E in concentrates on the oxidative stability of milk. In experiment 1, six multiparous Holstein-Friesian cows were offered 1 of 6 silage treatments in a cyclical changeover-design experiment, with four 4-wk periods. The silages were grass, red clover, white clover, alfalfa, grass and red clover mixture (50:50 on a DM basis), and grass and white clover mixture (50:50 on a DM basis). In experiment 2, 8 cows were used in a changeover-design experiment with three 4-wk periods. The 4 treatments were a factorial combination of forages (grass silage or red clover silage) and supplemental vitamin E in the form of all-rac-alpha-tocopheryl acetate (29 or 290 IU/kg of DM in the concentrate). All forages were offered ad libitum and a flat rate of concentrates (8 kg/d) was fed in both experiments. Red clover silage led to significantly higher forage intakes, milk yields, and milk protein percentage in experiment 2, which was in agreement with results from experiment 1. There was no effect of vitamin E on feed intake, milk production, or milk fat and protein percentage. Red clover silage also led to significant changes in milk fatty acid profiles, particularly increased levels of polyunsaturated fatty acids. Milk samples were stored at 4 degrees C and 20 degrees C and analyzed for alpha-tocopherol and thiobarbituric acid reactive substances at intervals to determine oxidative stability. Diets based on red clover and alfalfa silages were associated with more rapid loss of alpha-tocopherol and increased production of thiobarbituric acid reactive substances during the storage of milk in comparison with diets based on grass silage. The increased oxidative deterioration of milk produced from cows fed red clover silage was avoided by vitamin E supplementation.
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Affiliation(s)
- R M Al-Mabruk
- Institute of Rural Studies, University of Wales, Aberystwyth SY23 3AL, UK
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69
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Dewhurst RJ, Evans RT, Scollan ND, Moorby JM, Merry RJ, Wilkins RJ. Comparison of grass and legume silages for milk production. 2. In vivo and in sacco evaluations of rumen function. J Dairy Sci 2003; 86:2612-21. [PMID: 12939085 DOI: 10.3168/jds.s0022-0302(03)73856-9] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Two experiments were conducted to investigate the basis for higher voluntary intakes and increased alpha-linolenic acid content in milk from cows offered clover silages. Six cows with rumen and duodenal cannulae were used in a four-period changeover-design experiment. Cows received 8 kg/d of dairy concentrate and had ad libitum access to one of six silage treatments: grass, red clover, white clover, alfalfa, and 50/50 (dry matter basis) mixtures of grass with red clover or white clover. The rumen fermentability of grass, red clover, white clover, and grass/red clover silages was also evaluated in a nylon bag study. Legume silages led to increased dry matter intake and milk production in comparison with grass silage. There was no significant effect of legume silages on rumen pH and volatile fatty acid concentrations, but a significant increase in rumen ammonia concentration with the legume silages, reflecting their higher protein content. The inclusion of white clover or alfalfa silage, but not red clover silage, in diets led to an increase in molar proportions of isobutyric, iso-valeric, and n-valeric acids in comparison with diets based on grass silage. Rumen fill was significantly lower, and rumen passage rates were significantly higher for cows offered alfalfa or white clover silages. However, the markedly different particle size distribution of rumen contents with these feeds suggests very different mechanisms for the high intake characteristics: high rates of particle breakdown and passage with alfalfa, and high rates of fermentation and passage with white clover. Microbial energetic efficiency (grams microbial N per kilogram organic matter apparently digested in the rumen) was highest for cows offered alfalfa silage, intermediate for clover silage, and lowest for cows offered grass silage. These differences reflect the higher rumen outflow rates for legume silages in comparison with grass silage. However, the effect of these differences on N-use efficiency (feed to milk) was probably quite small in comparison with effects of N intake. Although the biohydrogenation of alpha-linolenic acid was still high for red clover silage (86.1% compared with 94.3% for grass silage), there was a 240% increase in the proportion of alpha-linolenic acid passing through the rumen. This explains the increased recovery of alpha-linolenic acid from feed into milk with diets based on red clover silage.
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Affiliation(s)
- R J Dewhurst
- Institute of Grassland and Environmental Research, Plas Gogerddan, Aberystwyth SY23 3EB, UK.
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