Supplemental safflower oil affects the fatty acid profile, including conjugated linoleic acid, of lamb

The objective of this study was to determine whether increasing levels of dietary safflower oil would alter unsaturated fat (especially CLA) and tocopherol content of lamb, animal performance, carcass characteristics, or color stability of lamb muscle tissue. Targhee x Rambouillet wethers (n = 60) were assigned to one of three diets (four pens per treatment with five lambs per pen) in a completely random design. Diets were formulated with supplemental safflower oil at 0 (control), 3, or 6% (as-fed basis) of the diet. Diets containing approximately 80% concentrate and 20% roughage were formulated, on a DM basis, to be isocaloric and isonitrogenous and to meet or exceed NRC requirements for Ca, P, and other nutrients. A subsample of 12 wethers per treatment was selected based on average BW (54 kg) and slaughtered. Carcass data (LM area, fat thickness, and internal fat content) and wholesale cut weight (leg, loin, rack, shoulder, breast, and foreshank), along with fatty acid, tocopherol, and color analysis, were determined on each carcass. The LM and infraspinatus were sampled for fatty acid profile. Increasing safflower oil supplementation from 0 to 3 or 6% increased the proportion of linoleic acid in the diet from 49.93 to 55.32 to 62.38%, respectively, whereas the percentage of oleic acid decreased from 27.94 to 23.80 to 20.73%, respectively. The percentage of oil in the diet did not (P > or = 0.11) alter the growth and carcass characteristics of lambs, nor did it alter the tocopherol content or color stability of meat. Increasing levels of safflower oil in lamb diets decreased (P < 0.01) the weight percentage of oleic acid in the infraspinatus and LM, and increased linoleic acid (P < 0.01). Oil supplementation increased (P < 0.01) the weight percentage of various isomers of CLA in muscle, with the greatest change in the cis-9,trans-11 isomer. Supplementation of sheep diets with safflower oil, up to 6% of the diet, resulted in increasing levels of unsaturated fatty acids and CLA in the lean tissue, without adversely affecting growth performance, carcass characteristics, or color stability of lamb.     

Effects of rice straw particle size on digesta particle size distribution,nitrogen metabolism,blood biochemical parameters,microbial amino acid composition and intestinal amino acid digestibility in goats

Effects of rice straw particle size and physically effective neutral detergent fiber (peNDF) on particle size distribution of different digestive tract, nitrogen (N) metabolism, blood biochemical parameters, microbial amino acid (AA) composition and intestinal AA digestibility in goats were investigated. A 4 × 4 Latin square design was employed using four mature Liuyang black goats fitted with permanent ruminal, duodenal, and terminal ileal fistulae. During each of the four periods, goats were offered one of four diets that were similar in chemical composition, but varied in particle sizes and peNDF through alteration of the theoretical cut length of rice straw (10, 20, 40 and 80 mm, respectively). Dietary peNDF contents of four diets were 17.4, 20.9, 22.5 and 25.4%, respectively. Results showed that increasing particle size of rice straw and dietary peNDF significantly affected the particle size distributions of digesta in rumen, duodenum and ileum, except feces. However, increasing particle size of rice straw and peNDF did not affected N metabolism in goats, except the increased apparent N digestibility in rumen and large intestine, and the decreased apparent N digestibility in small intestine. Furthermore, increasing particle size of rice straw and peNDF showed little influence on the profile of blood biochemical parameters, microbial AA composition and intestinal AA digestibility in goats.     

Efficacy of l-glutamic acid,N,N-diacetic acid to improve the dietary trace mineral bioavailability in broilers

Trace minerals are commonly supplemented in the diets of farmed animals in levels exceeding biological requirements, resulting in extensive fecal excretion and environmental losses. Chelation of trace metal supplements with ethylenediaminetetraacetic acid (EDTA) can mitigate the effects of dietary antagonists by preserving the solubility of trace minerals. Lack of EDTA biodegradability, however, is of environmental concern. l-Glutamic acid, N,N-diacetic acid (GLDA) is a readily biodegradable chelating agent that could be used as a suitable alternative to EDTA. The latter was tested in sequential dose–response experiments in broiler chickens. Study 1 compared the effect of EDTA and GLDA in broilers on supplemental zinc availability at three levels of added zinc (5, 10, and 20 ppm) fed alone or in combination with molar amounts of GLDA or EDTA equivalent to chelate the added zinc, including negative (no supplemental zinc) and positive (80 ppm added zinc) control treatments. Study 2 quantified the effect of GLDA on the availability of native trace mineral feed content in a basal diet containing no supplemental minerals and supplemented with three levels of GLDA (54, 108, and 216 ppm). In study 1, serum and tibia Zn clearly responded to the increasing doses of dietary zinc with a significant response to the presence of EDTA and GLDA (P < 0.05). These results are also indicative of the equivalent nutritional properties between GLDA and EDTA. In study 2, zinc levels in serum and tibia were also increased with the addition of GLDA to a basal diet lacking supplemental trace minerals, where serum zinc levels were 60% higher at the 216 ppm inclusion level. Similar to the reported effects of EDTA, these studies demonstrate that dietary GLDA may have enhanced zinc solubility in the gastrointestinal tract and subsequently enhanced availability for absorption, resulting in improved nutritional zinc status in zinc-deficient diets. As such, GLDA can be an effective nutritional tool to reduce supplemental zinc levels in broiler diets, thereby maintaining health and performance while reducing the environmental footprint of food-producing animals.     

Effect of dietary high-oleic acid sunflower seed, palm oil and vitamin E supplementation on broiler performance, fatty acid composition and oxidation susceptibility of meat

1. A study was conducted to evaluate the effect of inclusion of two fat sources: high-oleic acid sunflower seed (HOASS; 0, 50, 100, 150 and 200 g/kg diet) and palm oil (PO), and dietary supplementation of vitamin E (alpha-tocopheryl acetate, 200 mg/kg diet) on performance, fatty acid composition and susceptibility to oxidation of white and dark chicken meat during refrigerated storage. Female chicks (3 to 6 weeks) were given one of 5 diets containing 90 g/kg of added fat with increasing monounsaturated fatty acid (MUFA) content, adjusted by progressively replacing PO by HOASS. 2. Body weight gain and gain:food ratio of birds were depressed in diets containing the highest proportions of HOASS (150 and 200 g/kg). Relative abdominal fat was reduced in birds fed diets including HOASS, except in the diet containing 100 g HOASS/kg. The inclusion of alpha-tocopheryl acetate improved body weight gain and gain:food ratio. 3. According to the fatty acid profile of the diets, saturated and polyunsaturated fatty acid (SFA and PUFA, respectively) contents were significantly reduced and MUFA content was significantly increased in white and dark chicken meats when the saturated oil, PO, was replaced progressively by HOASS in the diet. The inclusion of alpha-tocopheryl acetate increased PUFA content in both meats. 4. After 4 and 7 d of refrigerated storage, white and dark meat samples obtained from birds fed on diets containing HOASS had significantly lower thiobarbituric acid reacting substance (TBARS) values than those derived from the PO diet. The addition of alpha-tocopheryl acetate significantly reduced the lipid oxidation in white and dark meat. 5. Overall, the results showed that increasing MUFA content of chicken meat by replacing dietary PO with HOASS (up to 100 g/kg) did not adversely affect broiler performance and reduced the susceptibility of meat to oxidation during refrigerated storage. Dietary alpha-tocopherol supplementation improved chicken performance and was effective in protecting lipid meat from oxidation.     

Effect of dietary γ-aminobutyric acid on laying performance,egg quality,immune activity and endocrine hormone in heat-stressed Roman hens

This study was conducted to evaluate the effect of γ-aminobutyric acid (GABA) on laying performance, egg quality, digestive enzyme activity, hormone level and immune activities in Roman hens under heat stress. Roman hens (320 days old) were fed with 0, 25, 50, 75 and 100 mg/kg GABA, respectively during a 60-day experiment. Compared with control, supplementation of 50 mg/kg GABA improved the laying performance and egg quality by significantly increasing egg production, average egg weight and shell strength (P < 0.05), while decreasing the feed–egg ratio and cholesterol level. Anti-oxidation activity was improved by significantly increasing the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), but decreasing malondialdehyde level in serum (P < 0.05), while significantly increasing the glucose and total protein (TP) level, follicle stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E₂), insulin, triiodothyronine (T₃) and free triiodothyronine (FT₃) levels, and IgG, IgA and complement (C3)activity in serum (P < 0.05). The results indicated that oral GABA improved laying performance and physical condition mainly by modulating hormone secretion, enhancing anti-oxidation and immune activity, and maintaining electrolyte balance. Fifty mg/kg was the optimum level for laying hens under heat stress in the present study.     

饲用酸化剂中甲酸、乙酸、丙酸、乳酸、柠檬酸的同步测定

实验建立利用高效液相色谱同时测定饲用酸化剂中甲酸、乙酸、丙酸、乳酸、柠檬酸含量的方法。采用Grom-Sil org acid柱(250 mm×2.1 mm,5μm)进行分析。流动相为pH值2.5磷酸水溶液;流速为1.0 ml/min;检测波长为210 nm;柱温为30℃。在此色谱条件下,5种有机酸分离良好。平均回收率均大于85%,RSD小于10.0%。对实际样品的检测结果表明:该方法操作简便易行,准确可靠。     

Effect of dietary fish oil substitution with linseed oil on the performance, tissue fatty acid profile, metabolism, and oxidative stability of Atlantic salmon

The objective of this experiment was to test the effect of total or partial substitution of dietary fish oil (FO) by linseed oil (LO) in Atlantic salmon feeding on performance, liver and muscle fatty acid composition, selected lipogenic and lipolytic enzyme activities, and flesh oxidative stability. For 12 wk, fish (220 +/- 12 g of initial BW) were fed five experimental diets in which the FO was serially replaced by 25, 50, 75, and 100% LO. Total FO replacement by LO did not (P = 0.20) affect fish final weight, biometric indices, or i.m. fat contents. Liver and muscle neutral lipid (NL) composition responded to dietary treatments in different ways. Whereas the sum of n-3 PUFA in muscle followed a linear and quadratic pattern with increasing levels of LO, a linear (P = 0.005) effect was observed in the liver NL fraction. Total n-3 and n-6 PUFA contents in the polar lipid fraction (PL) were unaffected (P = 0.356) by dietary input of LO in muscle. Activity of liver glucose-6-P-dehydrogenase (G6PD) was greater with increasing levels of LO (P = 0.004). A time effect (P < 0.001) was observed in the concentration of lipid peroxidation products, expressed as thiobarbituric acid reactive substances, in fish flesh stored under refrigeration for 9 d; however, the progressive inclusion of LO in the feed did not affect (P = 0.125) flesh oxidation stability. In summary, LO can totally replace FO in Atlantic salmon feed without affecting growth performance and muscle susceptibility to lipid oxidation. Fatty acid metabolism in the liver was affected by LO, promoting G6PD activity and eicosatetraenoic acid accumulation; however, a 100% LO replacement decreased (P < 0.001) concentrations of eicosapentaenoic and docosahexaenoic acids in salmon muscle.     

Influence of picolinic acid on the uptake of 65zinc-amino acid complexes by the everted rat gut

Three hundred fifty rats were used in three experiments to: 1) validate the everted gut procedure as an in vitro technique for estimating Zn absorption, 2) determine the effect of increasing ratios of picolinic acid (PA) to Zn on Zn absorption and 3) determine the effect of PA on absorption of Zn and amino acid complexes at pH 6, 7 and 8. In the first experiment the time delay between tissue collection with subsequent storage in ice-cold saline and start of tissue incubation was 0, 10, 20 or 30 min. A linear decrease was observed for 65Zn uptake with increasing delay time. Lysine absorption was not affected by delay time. In the second experiment, molar ratios of PA:Zn of 0, .5, 1.0, 1.5, 2.0 and 2.5 with Zn held constant were evaluated. A linear decrease in 65Zn absorption from 65ZnCl2 occurred as the molar ratio of PA to Zn increased. In the third experiment, 0 and 5 molar ratios of PA to a constant Zn level were evaluated using 65ZnCl2, 65Zn-14C-methionine (ZnMet) and 65Zn-3H-lysine (ZnLys) at pH 6, 7 and 8. The addition of PA decreased Zn absorption regardless of Zn source. The data suggest that the Zn sources used were of similar biological value. The data do not support the theory that PA facilitates Zn absorption.     

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

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

Effect of glutamic acid content of the diet on the catabolic rate of isotope-labeled glutamic acid in rats. 3. Determination of 14CO2 and 15N excretion following intragastric infusion of 14C- and 15N-glutamic acid

Male rats (body weight 100 g) received during a 8 days experimental feeding period diets with different contents in glutamic acid. The daily feed intake was restricted to the energy maintenance level of 460 kJ/kg0.75. The diet contained a mixture of L-amino acids corresponding to the pattern of egg protein except glutamic acid. Glutamic acid was added successively at 10 levels (0 to 14,8% of dry matter) and the resulting diets were fed to groups of 4 animals each. At the end of the experimental feeding period 14C- and 15N-labelled glutamic acid were applied by intragastric infusion. CO2- and 14CO2-excretion was measured during the following 4 hours and the urinary N- and 15N-excretion during the following 24 hours. The CO2-excretion decreased from 53 to 44 mmol CO2/100 g body weight with increasing levels of dietary glutamic acid. This change seems to result from the increasing proportion of amino acids as an energetic fuel. While the amount of oxidized glutamic acid increased with increasing supplements of glutamic acid the relative 14CO2-excretion decreased from 57 to 48% of the applied radioactivity. The urinary 15N-excretion during 24 hours was 31% of the given amount of 15N if no glutamic acid was included in the diet. This proportion increased successively up to 52% in the case of the highest supply of glutamic acid. Because the total N-excretion increased at the same extent as the 15N-excretion a complete mixing of the NH2-groups resulting from glutamic acid due to desamination with the ammonia pool was assumed. No correlation between glutamic acid content of the diet and specific radioactivity of CO2 or atom-% 15N excess of urinary N was observed.     

Duration of feeding conjugated linoleic acid influences growth performance, carcass traits, and meat quality of finishing barrows

Conjugated linoleic acid (CLA) was fed to growing-finishing barrows (n = 92) at 0.75% of the diet. A commercial CLA preparation (CLA 60) containing 60% CLA isomers was included at 1.25% to provide 0.75% CLA in the diet. The inclusion of CLA in diets was initiated at various BW and fed until slaughter. Growth, carcass, meat quality, physical, chemical, and sensory data were collected and analyzed. Treatments T1, T2, T3, and T4 included the last 0, 29, 56 and 87 kg, respectively, of weight gain before slaughter. Average daily gain and feed intake were not affected (P > or = 0.06) by CLA, but gain:feed responded quadratically (P = 0.05), over the entire BW gain (28 to 115 kg) with pigs of T2 and T3 having the greatest gain:feed. Loin muscle area increased (P = 0.01) linearly with increasing weight gain while fed CLA, and 10th rib, first rib, and last rib fat depth decreased (P < or = 0.05) linearly. Subjective quality measures on loin muscles increased linearly for marbling (P < 0.05) and tended to increase for firmness (P = 0.07) with increasing weight gain while barrows were fed CLA. Objective Hunter color values for loin chops from T1 and T4 were not different for L* (P = 0.12) or a* (P = 0.08) values but were higher (P < 0.05) for b* values with CLA feeding. Lipid oxidation values of loin muscle tissue were lower (P < 0.05) for pigs fed CLA (T1 vs T4). Increasing the period of weight gain while feeding CLA linearly increased (P < 0.01) saturated fatty acids and CLA isomers in loin tissue and linearly increased (P < 0.01) saturated fatty acids and CLA isomers in subcutaneous adipose tissue. Sensory panel characteristics of loin chops were not changed (P > 0.05) by feeding CLA. Increased gain:feed, increased loin muscle area, decreased fat depth, and improvements in marbling and firmness with CLA feeding could result in improved profitability of pork production systems.     

外源多胺对葡萄果实发育过程中糖酸含量的影响

本试验通过对藤稔葡萄喷施不同浓度Put（腐胺）,研究了Put对葡萄果实发育过程中糖、酸的含量变化。结果表明,Put有增糖降酸的作用,对增进果实品质有良好的作用。     

Effect of chlorogenic acid on intestinal inflammation,antioxidant status,and microbial community of young hens challenged with acute heat stress

Heat stress in poultry is deleterious to productive performance. Chlorogenic acid (CGA) exerts antibacterial, anti-inflammatory, and antioxidant properties. This study was conducted to evaluate the effects of dietary supplemental CGA on the intestinal health and cecal microbiota composition of young hens challenged with acute heat stress. 100-day-old Hy-line brown pullets were randomly divided into four groups. The control group (C) and heat stress group (HS) received a basal diet. HS + CGA₃₀₀ group and HS + CGA₆₀₀ group received a basal diet supplemented with 300- and 600-mg/kg CGA, respectively, for 2 weeks before heat stress exposure. Pullets of HS, HS + CGA₃₀₀, and HS + CGA₆₀₀ group were exposed to 38°C for 4 h while the control group was maintained at 25°C. In this study, dietary CGA supplementation had effect on mitigate the decreased T-AOC and T-SOD activities and the increasing of IL-1β and TNFα induced by acute heat stress. Dietary supplementation with 600 mg/kg CGA had better effect on increasing the relative abundance of beneficial bacterial genera, such as Rikenellaceae RC9_gut_group, Ruminococcaceae UCG-005, and Christensenellaceae R-7_group, and deceasing bacteria genera involved in inflammation, such as Sutterella species. Therefore, CGA can ameliorate acute heat stress damage through suppressing inflammation and improved antioxidant capacity and cecal microbiota composition.     

Effects of dietary glutamine and gamma-aminobutyric acid on meat colour,pH, composition,and water-holding characteristic in broilers under cyclic heat stress

1. An experiment was conducted to evaluate the effects of dietary glutamine (Gln, 0 and 5?g/kg) and gamma-aminobutyric acid (GABA, 0 and 100?mg/kg) on raw breast meat colour, pH, composition and water-holding characteristic of broilers under cyclic heat stress (HS).

2. A total of 360 21-d-old Arbor Acres male chicks were randomly assigned to 5 treatment groups (6 replicates of 12 birds per cage). The positive control (PC) broilers were kept in a thermoneutral chamber (22–24°C) and fed on the basal diet. The other 4 groups were kept in a cyclic HS chamber (30–34°C) for 9?h (from 09:00 to 18:00).

3. A significant increase was observed in breast meat lightness at 28, 35 and 42?d; and pH values at 28, 35 and 42?d; while a significant decrease was observed in breast meat cooking loss (CL) and contents of moisture, crude protein (CP), crude fat (CF) and crude ash (CA) due to HS.

4. The supplementation with 0·5?g?Gln/kg decreased lightness at 28, 35 and 42?d; while increasing redness at 28?d, yellowness at 35?d, contents of CP, CF and CA, thawing loss (TL) and drip loss (DL). The addition of 100?mg?GABA/kg decreased lightness at 28 and 35?d, pH value at 28, 35 and 42?d, and TL; while increasing redness at 28?d, 35 and 42?d, contents of moisture, CP and CF.

5. The lightness, redness, and pH value; contents of moisture, CP, CF and CA; and TL, DL and CL of breast meat of broilers fed with the mixture of Gln and GABA under cyclic HS were similar to those of the broilers in the PC group.

6. Significant interactions were found between Gln and GABA for yellowness at 28 and 35?d; pH at 28, 35 and 42?d; moisture content, CP content, water-holding capacity and TL.

7. These results demonstrated that dietary Gln and GABA offer a potential nutritional strategy to prevent cyclic HS-related depression in broiler meat chemical composition and quality.     

Impact of feeding various amounts of wet and dry distillers grains to yearling steers on palatability, fatty acid profile, and retail case life of longissimus muscle

Due to increased production of ethanol, abundance of distillers grains (DG) is increasing. Steers (n = 176) were assigned to 1 of 5 treatment groups: steam-flaked corn (SFC), 10% dry DG (DDG), 10% wet DG (WDG), 20% WDG, or 30% WDG. The objectives were to determine the effects of feeding greater amounts of WDG, or DDG on meat quality. Steaks, 2.54 cm, were cut from strip loins and identified for simulated retail display, Warner-Bratzler shear force analysis, palatability, and fatty acid composition. Steaks from cattle fed 10% WDG and 30% WDG had smaller (P < 0.05) Warner-Bratzler shear force values than steaks from cattle fed 20% WDG. Trained sensory panelists found no differences (P > 0.05) in overall tenderness and off-flavors. No differences were found in total SFA and MUFA composition among treatments; however, 20% and 30% WDG had a greater proportion of PUFA and n-6 fatty acids than 10% WDG. No differences were found during simulated retail display between various amounts of WDG. Further research needs to be conducted to evaluate methods that aid in increasing shelf life of steaks from cattle fed greater rates of WDG.     

Aromatic amino acid requirement of the lactating sow

Six mature Yorkshire X Landrace sows were randomly assigned to a 6 X 6 Latin-square experiment on d 5 of lactation to determine the total phenylalanine (Phe) and tyrosine (Tyr) requirement. A control diet of corn sugar, cornstarch, whey, L-glutamic acid, solka floc, soybean oil, amino acids, minerals and vitamins was supplemented with L-Phe to provide .30 (basal), .45, .60, .75, .90 and 1.05% total aromatic amino acids (TAAA). Each diet was fed to a maximum of 5.5 kg/d within each of six 10-d periods. Feed intake, average pig weight gain and sow milk yield decreased linearly (P less than .01) with increasing period. Sow milk yield was maximized at .75% TAAA (quadratic, P less than .10), but average pig weight gain did not reflect the higher yield. Urea nitrogen decreased quadratically with increasing dietary Phe in both plasma (P less than .05) and urine (P less than .01) to a breakpoint at .56% TAAA. Plasma Phe increased (quadratic, P less than .01) as dietary TAAA increased, but no clear inflection point was obtained. A sharp rise (quadratic, P less than .001) in plasma Tyr occurred at .73% dietary TAAA. Plasma lysine decreased (linear, P less than .001) to a low level at .76% TAAA, but plasma methionine was unaffected by treatment. Urine allantoin/urea X protein intake was maximized at .61% TAAA (quadratic, P less than .01). Nitrogen (N) intake varied among diets (quadratic, P less than .05), but fecal N was not altered by TAAA level.(ABSTRACT TRUNCATED AT 250 WORDS)     

Fatty acid composition of ruminal bacteria and protozoa, with emphasis on conjugated linoleic acid, vaccenic acid, and odd-chain and branched-chain fatty acids

Knowledge of the fatty acid profile of microbial lipids is of great nutritional importance to the animals and, subsequently, their products. This study was conducted to examine the fatty acid profiles of mixed rumen bacteria and protozoa. Bacterial and protozoal cells were isolated by differential centrifugation of rumen contents. The main fatty acids were palmitic (16:0) and stearic (18:0) in both the bacterial and protozoal fractions. Palmitic acid was 74% greater in the protozoal fatty acids than in the bacterial fatty acids, whereas bacteria had 2.25-times greater stearic acid (18:0) proportions compared with protozoa. The total odd-chain plus branched-chain fatty acids were 16.5% of bacterial fatty acids and 11.0% of protozoal fatty acids. The anteiso-17:0 proportions in bacterial and protozoal fatty acids were 1.4 and 2.9%, respectively. The most abundant trans-18:1 isomer, vaccenic acid (18:1 trans-11), was 6.6% of total fatty acids in protozoa and 2.0% of total fatty acids in bacteria. The cis-9, trans-11 CLA was 8.6-times greater in the protozoal fraction (1.32% of total fatty acids) than in the bacterial fraction (0.15%). These results suggest that the presence of protozoa in the rumen may increase the supply of CLA and other unsaturated fatty acids for lower gut absorption by ruminants.     

Supplemental algal meal alters the ruminal trans-18:1 fatty acid and conjugated linoleic acid composition in cattle

The effects of dietary algal supplementation, a source of docosahexaenoic acid, on the fatty acid profile of rumen lipids in cattle were evaluated, with special emphasis on CLA and trans fatty acids produced by rumen microbes. A diet based on corn silage was fed with supplements containing the following: 1) no algal meal and fed at 2.1 kg of DM/d (control), 2) algal meal and fed at 1.1 kg of DM/d (low algal meal), 3) algal meal and fed at 2.1 kg of DM/d (medium algal meal), and 4) algal meal and fed at 4.2 kg of DM/d (high algal meal). A modified lipid extraction procedure was developed to analyze the lipid changes in rumen fluid. The percentage of stearic acid (18:0) in rumen fluid was decreased by algal meal supplementation (P < 0.001) compared with control and was linearly dependent on the level of algal meal supplementation (P = 0.005). Total trans-18:1 in rumen fluid of cattle fed the control diet was 19% of total fatty acids. Addition of algal meal increased (P < 0.001) total trans-18:1 up to 43%, mostly due to 18:1 trans-10 that increased (P = 0.002) to 29.5% of total rumen fatty acids. This increase in 18:1 trans-10 seems to suggest a change in the rumen microbial population. Vaccenic acid (18:1 trans-11) increased quadratically (P = 0.005) with increasing level of algal meal supplementation in the diets. The total CLA content was low in the control (<0.9%) and increased with dietary algal meal addition, although not significantly; the greatest level was 1.5% with the medium algal meal diet. The increase of rumenic acid (cis-9, trans-11 CLA) was quadratic (P = 0.05) with algal meal supplementation, whereas trans-10, cis-12 CLA increased linearly with increased level of algal meal from 0.08 to 0.13% (P = 0.03). The ratio of trans-11 (cis-9, trans-11 CLA + 18:1 trans-11) to trans-10 (trans-10, cis-12 CLA + 18:1 trans-10) decreased from 2.45 to 0.77, 0.87, and 0.21 for the control, low algal meal, medium algal meal, and high algal meal diets, respectively. The content of docosahexaenoic acid in rumen fluid increased (P = 0.002) from 0.3 to 1.4% of total fatty acids with increasing level of algal meal supplementation in the diets. Our results suggest that algal meal inhibits the reduction of trans-18:1 to 18:0, giving rise to the high trans-18:1 content. In conclusion, algal meal could be used to increase the concentration in rumen contents of trans-18:1 isomers that serve as precursors for CLA biosynthesis in the tissues of ruminants.     

Effects of malic acid on feed intake, milk yield, milk components and metabolites in early lactation Holstein dairy cows

The objective of this study was to evaluate the effects of malic acid (MA) on feed intake, milk yield and composition, blood metabolites and energy balance in early lactation Holstein dairy cows from 1 to 63 day in milk (DIM). Twenty-eight multiparous Holstein dairy cows, blocked by lactation number, previous 305-d mature equivalent milk production, and expected calving date, were arranged into four groups in a randomized block design. Treatments were: control (without MA), LMA, MMA and HMA with 70, 140 and 210 g malic acid per cow per day, respectively. The supplement of food grade MA (99.8% of MA) was hand-mixed into the top one-third of the daily ration. Cows were fed ad libitum a total mixed ration consisting of equal proportion of forage and concentrate. Milk yield increased (P = 0.04), but feed intake and milk components were not affected (P > 0.05) by MA supplementation. The energy balance, expressed as the difference between energy input and output, tended to be higher (P = 0.08) for MA supplemented cows during the 63-DIM period MA and supplemented cows showed a trend (P = 0.07) toward less loss of BW during the 63-day period, especially during the first 21-day of lactation. Concentrations of plasma glucose and serum insulin were higher for cows fed LMA, MMA, and HMA relative to control and linearly (P < 0.01) increased with increasing MA supplementation. Concentrations of non-esterified fatty acids (NEFA), beta-hydroxybutyrate (BHBA) and urine ketones were lower for MA-supplemented cows at 7, 14 and 21 DIM of lactation and linearly (P < 0.01) decreased with increasing MA supplementation. Although feed intake was not affected, milk yield increased, MA-supplemented cows experienced higher concentrations of plasma glucose and serum insulin, lower concentrations of plasma BHBA and NEFA, and lower concentrations of urine ketones, suggesting that nutrient digestibilities and energy availability may have been improved.     

Arterial baroreflex control of heart rate in the horse, pig, and calf

The heart rate (HR) response to stepwise changes in mean arterial pressure (MAP) produced by methoxamine and sodium nitroprusside was studied in conscious horses, pigs, and calves. The respective steady-state arterial baroreflex sensitivities (delta HR/delta MAP expressed as beats min-1 . mm of Hg-1) were -1.20, -1.21, and -0.39 for decreasing MAP and -0.08, -0.91, and -0.56 for increasing MAP. After parasympathetic nervous system (PNS) blockade with atropine, the reflex sensitivity to decreasing MAP in horses and the pigs decreased to -0.62 and -0.65, respectively (P less than 0.05), whereas the sensitivity in calves was not significantly different from the calves' base-line sensitivity (P greater than 0.05). In pigs, the sensitivity to increasing MAP decreased to -0.43 after PNS blockade (P less than 0.05). Horses and calves had a response to small increases in MAP similar to that observed in the absence of PNS blockade. There was no additional change in HR with larger increases in MAP in these 2 species. These responses indicate that varying degrees of mixed PNS and sympathetic nervous system activity changes mediate the baroreflex change in HR seen for increasing and decreasing MAP in pigs and for decreasing MAP in horses. Predominantly PNS activity is responsible for the response to increasing MAP in the horses and calves, whereas predominantly sympathetic nervous system activity is responsible for the response to decreasing MAP in calves. Comparisons were made between the observations in these 3 species and other mammalian species.