Effects of dietary camelina, flaxseed, and canola oil supplementation on plasma fatty acid concentrations and health parameters in horses.

Camelina (Camelina sativa) is a hardy, low-input oilseed crop that provides a rich source of the n-3 fatty acid, α-linolenic acid (ALA). The primary purpose of the present study was to assess the effects of dietary camelina oil (CAM) consumption on various health parameters, as compared to horses fed canola oil (OLA) or flax oil (FLX). Secondly, to determine how dietary CAM, FLX, and OLA alter circulating plasma total lipids across time. Thirty horses, from three separate herds, were used for this study [14.9 years ± 5.3 years; 544 ± 66 kg calculated BW (mean ± SD)]. After a 4-week gradual acclimation period using sunflower oil mixed with soaked hay cubes, horses were balanced by location, age, sex, weight, and breed and randomly allocated to one of three treatment oils (CAM, OLA, or FLX) at an inclusion of 370 mg of oil/kg BW/day. Horses had ad libitum access to hay and/or pasture for the duration of the study. Body condition score (BCS), BW, oil intake, complete blood counts, plasma biochemical profiles, and plasma total lipids were measured on weeks 0, 2, 4, 8, and 16 throughout the 16-week treatment period. BW, BCS, and oil intake were analyzed using an ANOVA using PROC GLIMMIX in SAS Studio. Complete blood counts and biochemical profiles were analyzed using an ANCOVA, and fatty acids were analyzed using an ANOVA in PROC MIXED in SAS Studio. No differences were observed among treatment groups for BW, BCS, oil intake, complete blood counts, and biochemical parameters. Individual fatty acids that differed among treatments and/or across time were largely reflective of the different FA profiles of the oils provided. Most notably, plasma ALA was greater for FLX than OLA, but neither differed from CAM (P = 0.01). Linoleic acid did not differ among treatments or over time (P > 0.05). The n-6:n-3 ratio decreased over time for both CAM and FLX, and ratios were lower for FLX than OLA at week 16, but not different from CAM (P = 0.02). These results suggest that dietary CAM had no adverse effects on health parameters and that daily supplementation of CAM and FLX at 370 mg of oil/kg BW/day induces positive changes (a decrease) in the n-6:n-3 status of the horse. Consequently, CAM may be considered as an alternative oil to FLX in equine diets.

Effects of leucine or whey protein addition to an oral glucose solution on serum insulin, plasma glucose and plasma amino acid responses in horses at rest and following exercise.

REASONS FOR PERFORMING STUDY: Providing protein or amino acid mixtures in combination with glucose to post exercise in man has resulted in increases in the post feeding insulin response and in muscle glycogen and protein synthesis rates. However, whether protein and/or amino acids can modify the post exercise insulin responses in horses remains to be fully elucidated. OBJECTIVES: To determine whether whey protein or leucine addition to a glucose solution affects the post gavage plasma insulin, glucose and amino acid responses in horses and whether these responses are different following a period of exercise vs. rest. METHODS: Six mature, conditioned Thoroughbreds received a nasogastric gavage containing either 1 g/kg bwt glucose (G), G + 0.3 g/kg bwt whey protein (GW) or G + 0.3 g/kg bwt leucine (GL), following a period of either rest (R) or an exercise test on a high speed treadmill (EX). Each horse was studied under all 6 treatment conditions, separated by 10 day intervals. Blood samples were collected pre-exercise/rest, pregavage and at regular intervals up to 300 min post gavage. Plasma was analysed for glucose and amino acid concentrations and serum insulin concentrations were determined. RESULTS: There was a significantly (P < 0.05) greater insulin response in GL-R and GL-EX when compared to the other treatments. When compared to rest, post exercise plasma glucose responses were lower in G and GW but unchanged following GL administration. Plasma alanine concentrations were elevated post exercise in all EX treatments. With the exception of markedly elevated plasma leucine concentrations after GL-R and GL-EX, the plasma concentrations of all indispensable amino acids decreased during the post gavage period. CONCLUSIONS: Leucine but not whey protein augmented the serum insulin response to an oral glucose load. Leucine supplementation warrants further investigation as a means to increase the rate of post exercise muscle glycogen synthesis in horses.

Effects of nutritionally induced metabolic acidosis with or without glutamine infusion on acid-base balance, plasma amino acids, and plasma nonesterified fatty acids in sheep.

This study characterized the effects of nutritionally induced metabolic acidosis with or without Gln infusion on acid-base balance, plasma AA, and plasma NEFA in sheep. In a randomized complete block design with a 2 x 2 factorial arrangement of treatments, 24 fully fleeced sheep (Rideau-Arcott, 63.6 +/- 5.9 kg of BW) were fed a control supplement (CS; 300 g/d of canola meal) or an acidosis supplement (AS; 300 g/d of NutriChlor; HCl-treated canola meal), offered twice daily at 0700 and 1100 h. Sheep were infused at 1400 h daily with 0.3 g of L-glutamine per kg of BW or saline via jugular vein catheters for 7 d. The sheep were individually housed and limit-fed a basal diet of dehydrated alfalfa pellets (1.75 kg/d; 90% DM, 22% CP, and 1.2 Mcal of NE(g)/kg on a DM basis) offered twice daily at 1000 and 1300 h. Blood and urine was sampled daily between 1100 and 1130 h, and blood samples were analyzed for hematocrit, plasma pH, gases, strong ions, AA, and NEFA, whereas urine was analyzed for pH. The AS reduced (P < 0.01) DMI, urine and plasma pH, blood urea, partial pressure of CO(2), strong ion difference, and plasma HCO(3)(-), and increased (P < 0.01) plasma K(+), Ca(2+), and Cl(-). The AS with saline infusion increased (P

Plasma amino acid profile and expression of the ubiquitin-mediated proteolytic pathway in lambs with induced metabolic acidosis.

Metabolic acidosis is a condition often induced by ruminal acidosis. Identification of the specific proteolytic pathways affected by metabolic acidosis and characterization of AA concentration changes induced by metabolic acidosis in ruminants has yet to be confirmed. The objective of this study was to examine the effect of nutritionally induced metabolic acidosis on lamb plasma AA and tissue variables, including mRNA and protein expression of components of the ubiquitin-mediated proteolytic pathway. Lambs (n = 10) were divided evenly into treatment groups receiving alfalfa pellets supplemented with 1) a control canola meal supplement, or 2) HCl-treated canola meal supplement for a 10-d treatment period. On d 11, lambs were slaughtered and liver, muscle, and kidney samples were collected to determine mRNA expression of components of the ubiquitin-mediated proteolytic pathway and ubiquitin protein expression. Plasma concentrations of serine (P = 0.06), glycine (P = 0.002), and glutamine (P = 0.04) were greater in acidotic lambs compared with control animals, indicating that protein catabolism may be occurring. However, no alteration (P > 0.1) in messenger RNA expression of the proteasome subunit C8, ubiquitin-conjugating enzyme E2, or ubiquitin or in ubiquitin protein expression were observed. These results suggest that ubiquitin-mediated proteolysis is not the primary pathway of protein degradation in lambs afflicted with metabolic acidosis.

An estimate of the methionine requirement and its variability in growing pigs using the indicator amino acid oxidation technique.

Although AA requirements for the mean of a population of growing pigs have been established using traditional methods, there are no estimates of the variability within the population and whether this variation differs among AA. With the increased use of supplemental Lys in pig diets, there will be an increased need to supplement Met, commonly the second or third limiting AA in corn-soybean diets. The indicator AA oxidation method allows repeated measurements in a short period of time so that the AA requirement can be determined for individual pigs at a similar physiological stage. The objective of this study was to determine the mean Met requirement in individual gilts and to estimate the related variability. Six individually housed female pigs (initial BW = 8.8 kg, SD 1.5) each received diets providing 6 levels of dl-Met. The isonitrogenous and isoenergetic diets contained 0.187, 0.250, 0.290, 0.320, 0.350, and 0.377% Met (analyzed, as-fed basis). Cysteine (0.48%) and Lys (1.44%) concentrations were similar for all diets. Pigs were adapted for 6 d to the basal corn-soybean meal diet (0.187% Met), which was offered at 95 g/kg(0.75) of BW to ensure complete consumption of the test diets. During 4-h oxidation studies, 313.4 kBq, (SD 35.6) of L-[1-(14)C]Phe was mixed with each of 8 half-hourly meals, and expired CO(2) was collected. The breakpoint in Phe oxidation, representing the Met requirement, and its variability, was determined using 2-phase linear regression. Phenylalanine oxidation decreased as the Met content increased from 0.187 to 0.29%. Phenylalanine oxidation was not different (P > 0.2) for diets ranging from 0.320 to 0.377% Met. The dietary Met requirement varied from 0.320 to 0.373% for individual pigs. The mean Met requirement for individual pigs was determined to be 0.340% of diet (SD = 0.024%, CV= 7.1%), with 0.340, 0.364, and 0.388% covering the requirement of 50, 66, and 95% of the population, respectively. The present mean population estimate was similar to the recommended dietary Met concentration of 0.325% for pigs of this BW and feed intake. To maximize profitability, Met levels in starter pig diets should be determined, depending on the cost of crystalline Met and the fraction of the population whose requirement is to be met.

Effects of dietary strong acid anion challenge on regulation of acid-base balance in sheep.

The acid-base status of the extracellular fluid is directly affected by the concentrations of strong basic cations and strong acid anions that are absorbed into the bloodstream from the diet. The objective of this study was to develop and characterize a model for dietary acid challenge in sheep by decreasing the dietary cation-anion difference (DCAD) using NutriChlor (HCl-treated canola meal), an anionic feed supplement. Ten fully fleeced sheep (Rideau-Arcott, 54.3 +/- 6.7 kg of BW) were fed either a control supplement [200 g/d of canola meal, DCAD = 184 mEq/kg of DM, calculated as (Na+ + K+) - (Cl- + S2-)] or an anionic supplement (AS; 200 g/d of NutriChlor, DCAD = -206 mEq/kg of DM) offered twice daily at 0700 and 1100 in a randomized complete block design. The sheep were individually housed and limit-fed a basal diet of dehydrated alfalfa pellets (22% CP and 1.2 Mcal of NE(g)/kg, DM basis) at 1.1 kg of DM/d offered twice daily at 1000 and 1300. Two days before the beginning of the experiment, the sheep were fitted with vinyl catheters (0.86-mm i.d., 1.32-mm o.d.) in the left jugular vein to facilitate blood sampling. Blood and urine samples were obtained daily from 1100 to 1130 on d 1 through 9 and at 0700, 1000, 1300, 1600, and 1900 on d 10. Blood was analyzed for hematocrit, plasma pH, gases, strong ions, and total protein. Urine samples were analyzed for pH. The AS induced a nonrespiratory acid-base disturbance associated with lower (P < 0.05) plasma pH (7.47 vs. 7.39), lower (P < 0.05) urine pH (8.13 vs. 6.09), and lower (P < 0.05) strong ion difference (42.5 vs. 39.5). The AS reduced (P < 0.05) the concentration of plasma glucose, base excess, and bicarbonate and increased (P < 0.05) the concentration of K+ and Cl-. Lowering DCAD increased (P < 0.05) Ca2+ concentrations in plasma by 13%. In conclusion, this dietary model successfully induced a significant acid-base disturbance in sheep. Although the acidifying effects of negative DCAD in the diet may have short-term prophylactic effects of elevating the concentration of Ca2+ in plasma, negative DCAD may have detrimental effects on acid-base balance.