Relative bioavailability of phosphorus and true amino acid digestibility by poultry as affected by soybean extraction time and use of low-phytate soybeans.

The objectives of this study were to determine if lengthening the time that soybeans (SB) spend in the extractor during preparation of soybean meal (SBM) results in increased relative bioavailability of phosphorus without negatively impacting true amino acid digestibilities, and to compare those modified SBM with that produced from a low-phytate SB. Three SBM were prepared under uniform conditions with the exception of the length of time SB spent in the extractor [45 min (300 rpm), 60 min (225 rpm), or 90 min (150 rpm)]. A SBM prepared from low-phytate SB was obtained for comparison. Relative phosphorus bioavailability in chicks and true amino acid digestibilities by cecectomized roosters were determined. Increasing the length of time that SB spent in the extractor from 45 to 90 min resulted in lower phytate phosphorus and increased phosphorus bioavailability from 34 to 56%. However, this increase came at the expense of available lysine status, with the SBM extracted for 90 min containing less total lysine and less digestible lysine than the SBM extracted for 45 min (traditional extraction time). Phosphorus bioavailability from SBM prepared from low-phytate SB was 1.5 times higher than for SBM extracted for 45 min. Increasing the length of time that SB spend in the extractor led to an increase in bioavailable phosphorus but a decrease in bioavailable lysine, potentially negating the positive effect on phosphorus.

Effects of supplemental fructooligosaccharides plus mannanoligosaccharides on immune function and ileal and fecal microbial populations in adult dogs.

The goal of this study was to examine whether supplemental fructooligosaccharides (FOS) plus mannanoligosaccharides (MOS) influenced immune function and ileal and fecal microbial populations of adult dogs. Eight adult dogs surgically fitted with ileal cannulas were used in a crossover design. Dogs were fed 200 g of a dry, extruded, kibble diet twice daily. At each feeding, dogs were dosed with either 1 g sucrose (placebo) or 2 g FOS plus 1 g MOS orally via gelatin capsule. Fecal, ileal, and blood samples were collected at the end of each 14-d period to measure microbial populations and immune characteristics. Treatment least squares means were compared using the GLM procedure of SAS. Supplementation of FOS plus MOS increased fecal bifidobacteria and fecal and ileal lactobacilli concentrations. Dogs fed FOS plus MOS also tended to have lower blood neutrophils and greater blood lymphocytes vs placebo. Serum, fecal, and ileal immunoglobulin concentrations were unchanged by treatment. Supplementation of FOS plus MOS beneficially altered indices of gut health by improving ileal and fecal microbial ecology. Supplementation of FOS plus MOS also altered immune function by causing a shift in blood immune cells.

The effects of dry extrusion temperature of whole soybeans on digestion of protein and amino acids by steers.

Five Holstein steers (450 kg) with cannulas in the rumen, proximal duodenum, and terminal ileum were used in a 5 x 5 Latin square design to study the effects of extrusion temperature on site of digestion of nitrogenous compounds in whole soybeans. The basal diet contained 50% corn silage, 24% alfalfa hay, 16.6% corn starch, 4.05% ground corn, 1% urea, and 3.4% soybean oil. Raw soybeans or soybeans extruded at 116, 138, or 160 degrees C (diets 116, 138, and 160, respectively) replaced the soybean oil and most of the corn starch in the test diets. Total N (g/d) reaching the duodenum was 232, 293, 285, 308, and 299 for the basal, raw, 116, 138, and 160 diets, respectively. No differences were observed between the raw and extruded soybeans (P = 0.81), or for the linear or quadratic effects of extrusion temperature (P = 0.56 and P = 0.45, respectively). Nonbacterial N (g/d) reaching the duodenum was 63.1, 104.6, 106.7, 101.9, and 113.9 for the same diets, respectively, and was not influenced by extrusion or extrusion temperature. Nitrogen disappearance from the small intestine (g/d) was 150 for the basal diet, 194 for the raw soybean diet, and 187,221, and 213 for the 116,138, and 160 degrees C extruded diets, respectively; no differences were observed between the raw and the extruded soybeans, or for diets containing soybeans extruded at different temperatures. Nitrogen disappearance (% of N entering) from the small intestine was lower (P < 0.05) for steers fed the basal diet than for steers fed the soybean-supplemented diets (64.1 vs 68.5%). No differences (P > 0.10) due to extrusion temperature were detected for flows of individual, essential AA, nonessential AA, and total AA at the duodenum. As extrusion temperatures increased, there were linear increases (P < 0.10) in disappearance (g/d) of all individual AA from the small intestine except for methionine and glycine. Essential, nonessential, and total AA disappearance from the small intestine were increased linearly (P < 0.10) with increasing extrusion temperature. Extrusion of soybeans can protect soy protein against extensive ruminal degradation without compromising intestinal digestibility.

Concentrations of conjugated linoleic acid (cis-9, trans-11-octadecadienoic acid) are not increased in tissue lipids of cattle fed a high-concentrate diet supplemented with soybean oil.

Conjugated linoleic acid (CLA), a mixture of isomers of linoleic acid, has many beneficial effects, including decreased tumor growth in animal cancer models. The cis-9, trans-11 isomer of CLA (CLA9,11) can be formed in the rumen as an intermediate in biohydrogenation of linoleic acid. Recent data, however, indicate that tissue desaturation of trans-fatty acids is an important source of CLA9,11 in milk. Our objective was to determine whether supplementing a high-corn diet with soybean oil (SBO; a source of linoleic acid) would increase concentrations of CLA in ruminal contents and tissue lipids. Four ruminally cannulated steers were utilized in a Latin square design with 28-d periods. A control diet (80% cracked corn, 2.0% corn steep liquor, 8.0% ground corn cobs, and 10% supplement [soybean meal, ground shelled corn, minerals, and vitamins]) was supplemented with 2.5, 5.0, or 7.5% (DM basis) SBO. Supplemental SBO did not affect ruminal pH or concentrations of the major VFA. The proportion and amount (mg FA/g DM ruminal contents) of CLA9,11 were not increased by increasing dietary SBO. However, the proportion and amount of the trans-10, cis-12 CLA isomer (CLA10,12) in ruminal contents increased linearly (P < 0.006) as dietary SBO increased. Trans-18:1 isomers in ruminal contents increased linearly (P < 0.02) as dietary SBO increased. The proportion of CLA10,12 was correlated positively (P < 0.001) with proportions of trans-C 18:1 isomers in ruminal contents. Conversely, CLA9,11 was correlated negatively (P < 0.05) with the proportions of trans-18:1 in ruminal contents. The same high-corn diet, supplemented with 0 or 5% SBO, was fed to 20 Angus-Wagyu heifers for 102 d in a randomized complete block design to determine the effect of added SBO on tissue deposition of CLA. Supplemental SBO did not affect feed intake, gain:feed, or carcass quality. Tissue samples were obtained from the hindquarter, loin, forequarter, liver, large and small intestine, and subcutaneous, mesenteric, and perirenal adipose depots. The concentration of CLA9,11 was greatest in subcutaneous adipose tissue but was not affected in any tissue by SBO. Supplementing high-corn diets with SBO does not increase CLA9,11 concentrations in tissues of fattening heifers. Research is needed to identify regulatory factors for pathways of biohydrogenation that lead to increased concentrations of CLA10,12 in ruminal contents when high-oil, high-concentrate diets are fed.

The ratio of insoluble to soluble fiber components in soybean hulls affects ileal and total-tract nutrient digestibilities and fecal characteristics of dogs.

An experiment was conducted to evaluate the effects of soybean hulls (SH) containing varying ratios of insoluble:soluble fiber (I:S) on nutrient digestibilities and fecal characteristics of dogs. Ileally cannulated dogs (n = 6) were fed seven diets in a 6 x 7 Youden square arrangement of treatments. The seven diets included five SH-containing diets with I:S of 1.9, 2.7, 3.2, 5.2 or 7.2 and two diets containing either beet pulp (BP) or no supplemental fiber (control). Ileal digestibilities of DM, OM, CP, total dietary fiber (TDF), fat and gross energy (GE) were lower (P < 0.05) for dogs fed diets containing supplemental fiber compared with dogs fed the control diet. Fiber inclusion had a modest negative effect (P < 0.05) on total-tract DM, OM, fat and GE digestibilities compared with the control diet. Ileal digestibilities of DM and OM by dogs fed the SH treatments responded quadratically (P < 0.05) to I:S, with digestibility coefficients decreasing as the I:S approached 3.2. Highest ileal digestibilities were observed for diets with an I:S of 1.9 and 7.2. Similarly, a quadratic response (P < 0.05) was observed for digestibility of total amino acids at the ileum. Fecal outputs were lower (P < 0.001) when dogs consumed the control diet vs. fiber-containing diets. Among the SH-containing diets, there was a linear increase in fecal output as I:S increased (P = 0.031). The I:S in the diet affects DM and OM digestibilities at the ileum and affects fecal output, indicating that optimization of this ratio is desirable.

Fruit and vegetable fiber fermentation by gut microflora from canines.

The objective of this study was to assess fermentability by canine gut microflora to include shortchain fatty acid (SCFA) production, organic matter (OM) disappearance, and gas production of vegetable and fruit fiber sources compared to fiber standards (psyllium, citrus pectin, and Solka Floc). Fiber sources included apple pomace, carrot pomace, flaxseed, fruit blend (mixture of peach, almond, nectarine, and plum), grape pomace, pea hulls, pistachio, and tomato pomace. Substrates were fermented in vitro for 4, 12, and 24 h with fecal flora obtained from three healthy dogs. Citrus pectin had the highest OM disappearance, SCFA production, and gas production at all times of fermentation; psyllium was intermediate and Solka Floc was lowest. A wide variation in fermentability was noted among the vegetable and fruit fiber sources. Apple pomace, carrot pomace, and flaxseed had the greatest fermentability as assessed by OM disappearance. Pea hulls and tomato pomace had intermediate OM disappearances, and fruit blend, grape pomace, and pistachio were poorly fermented. Carrot pomace produced the largest amounts of gas and SCFA. Apple pomace produced high concentrations of gas but intermediate concentrations of SCFA. Pea hulls and tomato pomace produced intermediate concentrations of gas and SCFA, whereas flaxseed, fruit blend, grape pomace, and pistachio produced low amounts of these fermentation products. For all substrates collectively, OM disappearance was highly correlated with both gas production (r2 = 0.782 and 0.723 for 12- and 24-h values, respectively) and SCFA production (r2 = 0.737 and 0.738 for 12- and 24-h values, respectively). In general, OM disappearance, gas production, and SCFA production were related to the insoluble:soluble fiber ratio in the samples; as the insoluble:soluble ratio decreased (increased soluble fiber), the OM disappearance, gas production, and SCFA production increased.

Dietary fat supplementation effects on in vitro nutrient disappearance and in vivo nutrient intake and total tract digestibility by horses.

Addition of fat to the diet of the equine is a popular method of increasing energy density of the diet while reducing feed intake. Reducing feed intake is of interest to race horse trainers because additional feed is seen as additional weight and, therefore, a hindrance to performance. Limited information is available regarding the interactions of fat with other dietary components, particularly fiber, in the equine digestive system. The effect of dietary fat on in vitro nutrient disappearance in equine cecal fluid was studied in Exp. 1 using a split-plot design within a 2 x 2 Latin square. Two ponies were fed alfalfa (ALF) alone or alfalfa plus 100 g/d corn oil. Five substrates were used to determine in vitro DM disappearance, OM disappearance, NDF disappearance, and total dietary fiber (TDF) disappearance. The substrates included: ALF, tall fescue (TF), red clover (RC), soybean hulls (SBH), and rolled oats (RO). Fat supplementation did not affect in vitro DM, OM, or NDF disappearance. Addition of fat to the diet increased (P < 0.05) the disappearance of NDF in RO. Among substrates, in vitro DM and OM disappearance were highest (P < 0.05) for RO, followed by SBH, ALF, RC, and TF. In vitro NDF and TDF disappearance were highest (P < 0.05) for SBH, followed by RO, ALF, RC, and TF. In Exp. 2, the effects of varying levels of fat on nutrient intake and total tract digestibility were examined using a 4 x 4 Latin square design. Four mature mares were fed a 60% forage-40% concentrate diet containing different concentrations of fat: 0% supplemental fat control (C); 5% supplemental corn oil (5% CO); 10% supplemental corn oil (10% CO); or 15% supplemental corn oil (15% CO). Treatment did not affect intake of the concentrate portion of the diet or CP, gross energy, or NDF intake. Mares consuming the C diet had the highest (P < 0.05) intake of alfalfa cubes, DM, and OM, followed by those on the 10, 5, and 15% CO treatments, respectively. Treatment did not affect nutrient digestibility. Mares consuming the 15% CO diet had the highest (P < 0.05) fat digestibility, whereas those consuming C had the lowest fat digestibility. Fat in the form of CO generally had little effect on in vitro and in vivo nutrient digestibilities in horses.

In vitro fermentation characteristics of native and processed cereal grains and potato starch using ileal chyme from dogs.

Two in vitro experiments were conducted to evaluate the ability of small intestinal bacteria of dogs to ferment native and extruded cereal grains and potato starch and cereal grain and potato flours. Substrates included barley, corn, potato, rice, sorghum, and wheat. In addition to testing native grains and flours, extruded substrates also were tested. Substrates were extruded at low temperatures (LT; 79 to 93 degrees C) and high temperatures (HT; 124 to 140 degrees C) using a Wenger extruder (model TX-52). Substrates varied widely in concentrations of rapidly digestible starch (RDS), slowly digestible starch (SDS), resistant starch (RS), and total starch (TS). Extrusion of most substrates at HT vs LT resulted in increased RDS and decreased RS concentrations. Organic matter disappearance (OMD) values attributed to microbial fermentation for a 5-h period were as high as 27% for native extruded substrates (LT potato starch) and 39% for potato flour. Average OMD was higher for cereal and potato flours than for native extruded substrates (29.9 vs 25.4%). Average molar percentages of short-chain fatty acids produced from all substrates fermented for 5 h were 73, 14, and 13% (acetate, propionate, and butyrate, respectively). Average lactate production for substrates ranked as follows: flours > native and extruded cereal grains and potato starch (0.33 and 0.18 mmol/g OM, respectively). In vitro microbial fermentation of starches by ileal bacteria can be substantial and is affected by differences in starch source, fraction, and processed form.

Effects of saturation and esterification of fat sources on site and extent of digestion in steers: digestion of fatty acids, triglycerides, and energy.

Five steers (mean BW 526 kg) fitted with ruminal, duodenal, and ileal cannulas were used in a 5 x 6 Youden square design with 14-d periods. Diets contained chopped alfalfa hay, corn silage, and concentrate (25:35:40, DM basis). Treatments were 1) control (no added fat); 2) tallow (T), iodine value (IV) = 51.5; 3) partially hydrogenated tallow (PHT), IV = 30.7; 4) hydrogenated tallow (HT), IV = 6.9; 5) blend (1: 1) of HT and hydrogenated free fatty acids (HTHFA), IV = 9.0; and 6) hydrogenated free fatty acids (HFA), IV = 11.2. Fats replaced cornstarch in the control diet to supply 5% added fatty acids. Intake was restricted to 90% of ad libitum; DMI was similar among diets (mean 9 kg/d). Total fatty acid intake averaged 170, 500, 506, 525, 489, and 491 g/d for treatments 1 to 6, respectively. Flows of total C16, total C18, and total fatty acids to the duodenum were increased by supplemental fat; flows of total C18 and total fatty acids were greater than their intake for all treatments. Flow of total fatty acids associated with ruminal bacteria accounted for 50 and 17% of the total duodenal fatty acid flow for the control and fat-supplemented diets, respectively. Digestibility of total fatty acids entering the small intestine (74, 71, 62, 39, 53, and 63% for treatments 1 to 6, respectively) was greater for the control diet than for fat-supplemented diets and decreased as either saturation (T < PHT < HT) or esterification (HFA < HTHFA < HT) increased. Digestibilities of fatty acids in the total tract followed similar patterns. Ruminal lipolysis of dietary triglycerides decreased linearly as the degree of saturation of fat sources increased. Small intestinal disappearance of triglycerides (89, 75, 51, 44, 64, and 73% of duodenal flow for treatments 1 to 6, respectively) decreased linearly as either saturation or esterification increased. Flows and digestion of gross energy followed patterns similar to those for fatty acids and triglycerides. Resistance to ruminal and small intestinal lipolysis is a major factor contributing to the poor digestibility of highly saturated triglycerides.

Ruminal and total tract digestibilities in steers fed diets containing liquefied or prilled saturated fatty acids.

We studied the effects of the addition of liquefied vs prilled mostly saturated fatty acids (FA) to the concentrate portion of total mixed diets on ruminal and total tract digestibilities. Four Holstein steers (270 +/- 23 kg) fitted with ruminal and duodenal cannulas were used in a 4 x 4 Latin square design with 21-d periods. Diets contained (DM basis) 30.0% corn silage, 22.2% chopped alfalfa hay, 25.0% ground shelled corn, 12.5% soybean meal, and 5% of one of the following fat sources: 1) prilled FA (PFA), 2) choice white grease (triglycerides) added in liquid form (LTG), 3) 2.5% PFA + 2.5% LTG, or 4) 2.5% liquefied PFA (LFA) + 2.5% LTG. Ad libitum OM intake was not different (P > .10) among diets (mean 7.8 kg/d). Ruminal digestibilities of OM (35.7, 39.9, 42.2, and 37.3% for Diets 1 to 4, respectively) were greatest (P < .10) for the combination of PFA + LTG and lowest for PFA alone. Ruminal digestibilities of NDF, ADF, and starch did not differ (P > .10) among diets. Total tract digestibilities of OM, NDF, and ADF were greater (P < .10) for the diet containing LTG alone than for the diet containing LFA + LTG because of trends for greater postruminal digestibilities. The LFA + LTG diet resulted in a greater proportion of acetate and lower proportion of propionate in ruminal fluid than PFA alone (P < .10). The acetate:propionate ratio (3.53, 2.96, 3.10, and 2.89 for Diets 1 to 4, respectively) was lower (P < .05) for LFA + LTG or LTG alone than for PFA alone. Postruminal and total tract digestibilities of total FA (66.0, 76.0, 71.2, and 68.9% for Diets 1 to 4, respectively) were lower (P < .05) for PFA than for other diets. Addition of saturated FA in liquid form resulted in digestibilities and ruminal effects similar to the same saturated FA added in prilled form.

Supplemental cracked corn for steers fed fresh alfalfa: II. Protein and amino acid digestion.

The effects of different levels of cracked corn on N intake, ruminal bacterial CP synthesis, and duodenal flows and small intestinal digestion of amino acids (AA) in steers fed fresh alfalfa indoors were determined. Angus steers (n = 6; average BW 338 +/- 19 kg) cannulated in the rumen, duodenum, and ileum were fed each of five diets over five periods in a Latin square design with an extra animal. Steers consumed 1) alfalfa (20.4% CP, 41.6% NDF) ad libitum (AALF); 2), 3), and 4) AALF supplemented (S) with three levels of corn (.4, .8, or 1.2% of BW, respectively), or 5) alfalfa restricted (RALF) to the average forage intake of S steers. Average N intake and duodenal flow of nonammonia N (NAN) were greater (P < .01) in S than in RALF steers. Greater duodenal flows of NAN in S compared with RALF were due to a trend toward higher (P = .06) flows of both bacterial and dietary N. Levels of corn decreased (P < .01) linearly N intake and increased (P < .01) linearly duodenal flow of NAN owing to a numerical linear increase in nonbacterial N (P = .15) with no increase in bacterial N flow. Duodenal NAN flows as percentages of N intake increased (P < .01) linearly (69.3 to 91.0%) as corn increased. Ruminal NH3 N concentration, ruminal CP degradability, and the proportion of bacterial N in duodenal NAN were decreased (P < .01) linearly as corn increased. Efficiency of net microbial CP synthesis was not affected (P > .05) by treatment (average 42.6 and 30.9 g N/kg of OM apparently or truly digested in the rumen, respectively). Small intestinal disappearance of total N and individual AA, except for threonine and lysine, and small intestinal digestibility of N and individual AA, except for methionine, histidine, and proline, increased (P < .01) linearly with level of corn and were greater (P < .01) in S than in RALF steers. Supplementing corn to steers fed fresh alfalfa reduced ruminal N losses and CP degradability and increased the duodenal flow and the small intestinal disappearance and digestibility of total N and total, essential, and nonessential AA.

Performance and digestion by steers grazing tall fescue and supplemented with energy and protein.

We studied the effects of different levels of protein and energy supplementation on BW gains and sites of nutrient digestion in steers grazing the primary growth of endophyte-infected tall fescue (Festuca arundinacea Schreb cv. Kentucky 31). Angus steers (n = 168; mean BW = 246.8 +/- 15.0 kg) grazed tall fescue without supplementation (C) or were supplemented with 1.4 kg/d of cracked corn (CC1), 1.4 kg/d of corn gluten feed (CGF1), 2.8 kg/d of CC (CC2), 2.8 kg/d of CGF (CGF2), or .7 kg/d of cornstarch and .7 kg/d of corn gluten meal (CS-CGM) during an 85-d period in a randomized complete block design. Supplemented steers (S) had a higher (P = .03) ADG than the control steers (.64 vs .74 kg/d). There was an interaction (P = .02) between supplement type and level. Supplementation during the grazing period had no effect on subsequent feedlot ADG (average 1.3 kg/d). In a digestion study, Angus x Simmental steers (n = 4; 412 +/- 20.4 kg) fitted with cannulas in the esophagus, rumen, and duodenum grazed tall fescue (C), C + 3.1 kg/d CGF, C + 3.1 kg/d of cracked corn (CC), or C + 1.4 kg/d CS-CGM over four experimental periods in a Latin square design. The ruminal ammonia nitrogen concentration tended to be higher (P < .09) in C than in CGF and in CC (21.9 vs 19.2 mg/dL), but ruminal pH and total VFA concentration did not differ among treatments. Forage OM intakes were lower (P < .05) in steers supplemented with CC or CGF (an average of 7,570 g/d) than in C (9,658 g/d). Total OM intakes and digestibilities did not differ (P > .10) among treatments. Duodenal N flows and efficiencies of net ruminal microbial protein synthesis were not different (P > .10) among treatments. Supplementation of steers grazing primary growth of tall fescue improved animal gain but did not have a great effect on ruminal fermentation, OM digestion, or net ruminal microbial protein synthesis.

The influence of processed corn and supplemental fat on digestion of limit-fed diets and performance of beef cows.

Trial 1, 135 crossbred cows with calves were used to compare limit-fed corn-hay diets with ad libitum hay and cracked with whole corn in limit-fed diets. Diets were to supply similar TDN intakes. Cow-calf pairs were fed treatment diets from 24 h after parturition until the beginning of the breeding season (62+/-13 d). Cow and calf performance was not affected (P > .05) by intake level or corn processing. In Trial 2, 48 crossbred primiparous cows with calves were used to determine the effect of adding 4% fat to a limit-fed corn-hay diet. Diets were to provide similar TDN intakes. Cow-calf pairs were fed treatment diets from 24 h after parturition until the breeding season started (79+/-14 d). Cow weight, condition score change, and calf gain were not affected (P > .05) by supplemental fat. Milk yield and composition were not different (P > .05) 52 d postpartum. At 92 d postpartum, milk production was 65% greater (P = .01) for cows that received supplemental fat. In Trial 3, four cannulated steers were used to evaluate the influence of corn processing and fat supplementation on digestion. Feeding cracked corn improved (P < .05) DM and OM digestion compared with whole corn. Adding 4% supplemental fat did not influence (P > .05) digestion. Limit-feeding a corn-hay diet is an alternative to feeding ad libitum hay that can accomplish similar cow and calf performance. Supplementation of 4% fat can be used in a limit-fed diet without detrimental effects on digestion, lactation, or cow and calf performance.

Effects of saturation and esterification of fat sources on site and extent of digestion in steers: ruminal fermentation and digestion of organic matter, fiber, and nitrogen.

Five steers (average 526 kg) fitted with ruminal, duodenal, and ileal cannulas were used in a 5 x 6 Youden square design with 14-d periods. Diets contained chopped alfalfa hay, corn silage, and concentrate (25:35:40, DM basis). Treatments were 1) control (no added fat), 2) tallow (T), 3) partially hydrogenated tallow (PHT), 4) hydrogenated tallow (HT), 5) blend (1:1) of HT and hydrogenated free fatty acids (HTHFA), and 6) hydrogenated free fatty acids (HFA). Fats replaced cornstarch in the control diet to supply 5% added fatty acids. Intake was restricted to 90% of ad libitum; DMI was similar among diets (average 9 kg/d). Ruminal pH and molar proportion of propionate (P) were greater (P < .05) but total VFA concentration, proportion of acetate (A), A:P, and percentages of OM digested in the rumen and total tract were less (P < .05) when fat-supplemented diets were fed than when the control diet was fed. Total VFA concentration increased linearly (P < .05) as esterification of fat sources increased (HFA < HTHFA < HT). Acetate and A:P increased linearly (P < .10) but propionate and apparent total tract digestibility of OM decreased linearly (P < .05) as either saturation (T < PHT < HT) or esterification of fat sources increased. Ruminal NH3 N concentration increased linearly (P < .001) as saturation increased. Apparent ruminal digestibilities of ADF (P < .05) and NDF (P < .10) increased linearly as esterification increased. Flow of nonammonia nonmicrobial N to the duodenum was less (P < .10) but flow of microbial N was greater (P < .05) for the control diet than for fat-supplemented diets. Flows and small intestinal digestibilities of N and efficiencies of microbial protein synthesis were not altered by degree of saturation or esterification. Results confirm previous in vitro observations that T or HFA can alter ruminal digestion; however, because these effects usually are not observed in dairy cows, feed intake likely is very important in responses to supplemental fats.

The effects of chemical treatment of whole canola seed on intake, nutrient digestibilities, milk production, and milk fatty acids of Holstein cows.

To determine the effect of alkaline hydrogen peroxide treatment of whole canola seed on milk fatty acid composition, 12 multiparous lactating Holstein cows (618 kg, 47 d in milk) were fed total mixed rations in a replicated (3) 4 x 4 Latin square designed experiment. The control diet contained no supplemental fat source. Canola seed (11.2%), either crushed or treated with alkaline hydrogen peroxide or Megalac (5.6%) were supplemental fat sources in the crushed, treated, and calcium salts of long-chain fatty acids (Ca-LCFA) dietary treatments. Experimental periods consisted of 28 d, with 21 d of adaptation to diets and 7 d for data collection. Cows were offered ad libitum access to feed. Intakes, ruminal characteristics, and total tract apparent digestibilities were measured and are discussed. Production of milk and 4% fat-corrected milk were not different among treatment groups (average 35.0 and 32.8 kg/d, respectively). Milk fat percentages were greater (P = .02) for cows fed treated canola seed or Ca-LCFA than for cows fed crushed canola seed (average 3.71 vs 3.43%, respectively), but milk fat yield (kg/d) was unaffected. Cows fed fat-supplemented diets had lower milk protein percentages than cows fed the control diet. Within the fat-supplemented diet groups, cows fed crushed canola seed had greater milk protein percentages (P = .01) and yields (P < .01) than cows fed treated canola or Ca-LCFA. Milk fat from cows fed diets supplemented with canola seed (treated or crushed) had lower proportions of 14:0 and 16:0 and greater proportions of 18:0 and 18:1 than milk fat from cows fed the control or Ca-LCFA diets. Intakes, milk production, milk composition, and milk fatty acid profiles substantiate that treated canola seed was utilized by cows to an extent similar to that of crushed canola seed. Further definition of the method for treatment of canola seed may provide a strategy for adding higher levels of monounsaturated fatty acids to lactation diets to produce favorable alterations in milk fat composition.

The effects of chemical treatment of whole canola seed on lipid and protein digestion by steers.

Five Angus x Simmental steers (average BW 259 kg) cannulated in the rumen, proximal duodenum, and terminal ileum were fed five diets in a 5 x 5 Latin square design. Experimental periods were 14 d in length, with 10 d of diet adaptation and 4 d of sample collection. The basal diet contained (percentage of diet DM) ammoniated corn cobs (50%), alfalfa hay (22%), cornstarch grits (13%), corn (6.7%), cane molasses (5%), and urea (1.25%). Three canola seed-containing diets and a diet containing Ca salts of long-chain fatty acids (Ca-LCFA) were formulated by replacing cornstarch grits from the basal diet with the test feedstuffs. Whole canola seed untreated, crushed, or treated with a caustic alkaline solution and an oxidant were included at 10% of diet DM. The Ca-LCFA diet contained (percentage of diet DM) canola meal (5%) and Megalac (5%). Diets containing untreated, crushed, and treated canola seed and Ca-LCFA contained, on average, 5.6% more total fatty acids than the basal diet. Steers were fed 5.3 kg DM/d (2.05% of initial BW) in 12 equal portions (every 2 h). Ruminal fermentation characteristics and digestibilities of OM, GE, N, NDF, and ADF were unaffected (P > .05) by diet. Biohydrogenation of total 18-carbon unsaturated fatty acids was greater (P < .05) for steers fed the crushed canola seed-containing diet (72.0%) than for steers fed the untreated (27.9%) and treated (38.6%) canola seed-containing diets. Digestibility of total 18-carbon fatty acids in the small intestine was greater for steers fed the crushed canola seed (58.9% of duodenal flow) rather than the untreated canola seed (28.4% of duodenal flow) and intermediate for steers fed the treated canola seed (47.0% of duodenal flow). Chemical treatment of whole canola seed may be a viable method for the postruminal delivery of intestinally available unsaturated fatty acids to ruminants.

Nutrient digestion by ileal cannulated dogs as affected by dietary fibers with various fermentation characteristics.

We studied the effects of dietary fibers with various fermentation characteristics on nutrient digestion at the distal ileum and in the total tract of dogs. The following high-protein (34%), high-fat (23%) diets were fed: 1) a control treatment (CON) with 0% supplemental fiber; 2) beet pulp (BP), 7.5%; 3) low-cellulose mixture (LCM), 2.5% cellulose + 5.0% pectin; 4) high-cellulose mixture (HCM), 5.0% cellulose + 2.5% pectin; or 5) Solka Floc (SF), 7.5% cellulose. Nutrient intakes by fiber-supplemented dogs were similar among treatment groups but greater (P < .05) than for dogs fed the control diet. Digestion of nutrients at the distal ileum was similar among groups except for fat: the dogs fed BP digested less fat than those fed the other sources of dietary fiber. Digestion of amino acids at the distal ileum was similar for all groups, except for lysine, which increased (P < .05) in digestibility as dietary cellulose concentration increased. Dogs consuming LCM had lower apparent ileal digestibility values for all nutrients, including most amino acids, than dogs consuming HCM or SF. Total tract digestion of DM and OM by dogs fed supplemental fiber was less (P < .05) than for dogs fed the control diet. The BP treatment was higher than other fiber treatments in total tract digestion of OM (P < .10) and total dietary fiber (P < .05). Total tract digestibilities of all nutrients exhibited either linear or quadratic responses to dietary cellulose concentrations. Apparent ileal and total tract nutrient digestion was influenced by the source of dietary fiber consumed.

Effects of chemical treatment of whole canola seed on digestion of long-chain fatty acids by steers fed high or low forage diets.

The objective was to evaluate the effectiveness of alkaline H2O2 treatment of whole canola seed as a means of weakening the seed coat while simultaneously protecting long-chain unsaturated fatty acids from ruminal biohydrogenation without hindering their digestion in the lower gut. Six ruminally and duodenally cannulated beef steers were offered six isonitrogenous diets for ad libitum intake twice daily in a 6 x 6 Latin square design. Treatments were arranged as a 2 x 3 factorial with two forage percentages (70 vs. 30% of dietary DM as corn silage) and three forms of canola seed supplementation, including no canola seed or canola seed added at 10% of dietary DM as treated whole seed or as crushed seed. Canola seed contributed 5% added fat to the total diet. Treated whole canola seed was superior to crushed seed in increasing the amounts of C18:1, C18:2, and C18:3 flowing to the duodenum and the amounts digested postruminally. However, digestibilities of these long-chain fatty acids (as percentages of the amounts entering the small intestine) did not differ between diets containing canola seed as treated whole seed or crushed seed. Results suggest that chemically treated whole canola seed can be used as a means of postruminal delivery of digestible long-chain unsaturated fatty acids, especially C18:1, which contributes 62% of the total fatty acids in canola seed. Results also suggest that treated whole canola seed may be more beneficial when fed with low than with high forage diets.

Effects of forage percentage and canola seed on ruminal protein metabolism and duodenal flows of amino acids in steers.

The objective was to determine the effects of dietary forage percentage and fat supplementation on ruminal N metabolism, duodenal flows of AA, and digestion of N. Six ruminally and duodenally cannulated steers were offered six isonitrogenous diets for ad libitum intake twice daily in a 6 x 6 Latin square design. Treatments were arranged as a 2 x 3 factorial with two forage percentages (70 vs. 30% of dietary DM as corn silage) and three forms of canola seed supplementation, including no canola seed or canola seed added at 10% of dietary DM as whole seed treated with alkaline H2O2 or as crushed seed. No interactions between dietary forage percentage and canola seed supplementation occurred for any of the measurements. Duodenal flows of NAN and AA were greater for diets containing low forage than for diets containing high forage. However, duodenal flows of total N and NAN did not differ among diets when corrected for differences in intake. Efficiency of bacterial protein synthesis and duodenal flows of bacterial N and AA were increased when treated whole canola seed was supplemented. Apparent total tract digestibility of N was not altered by dietary forage percentage or canola seed supplementation. Results indicate that fat supplementation from canola seed (at 5% of dietary DM), in either form, had no effects on ruminal N metabolism or flows of AA to the duodenum and suggest that treated whole canola seed may stimulate ruminal bacterial protein synthesis.

In vitro fermentation of cellulose, beet pulp, citrus pulp, and citrus pectin using fecal inoculum from cats, dogs, horses, humans, and pigs and ruminal fluid from cattle.

We evaluated the influence of gastrointestinal tract microflora from several species on fiber fermentation characteristics in vitro. Selected fibrous substrates (cellulose, beet pulp, citrus pulp, and citrus pectin) were incubated for 6, 12, 24, and 48 h with ruminal fluid from cattle or feces from dogs, cats, pigs, horses, or humans. When data were pooled across all substrates and fermentation times, OM disappearance (29.4%) and acetate, propionate, butyrate, and total short-chain fatty acid (SCFA) production (1.09, .41, .12, and 1.61 mmol/g of OM, respectively) were lowest (P < .05), and lactate production (.23 mmol/g of OM) was greatest (P < .05) for horse fecal microflora compared with samples from the other species. The greatest (P < .05) acetate production resulted when substrates were fermented by cat fecal microflora (2.38 mmol/g of OM). The greatest (P < .05) propionate productions resulted from pig fecal and cattle ruminal microflora (.88 and .83 mmol/g of OM, respectively), and the greatest (P < .05) butyrate productions resulted from human and pig fecal microflora (.39 and .40 mmol/g of OM, respectively). Total SCFA production was greatest (P < .05) for cat fecal microflora (3.38 mmol/g of OM). When data were pooled across the species, substrate OM disappearance and SCFA production ranked from least to greatest in the following order: cellulose < beet pulp < citrus pulp < citrus pectin. The fermentability of different fibrous substrates by fecal or ruminal microflora from various species seems to be dependent not only on the fermentative activity of the microbial population but on other factors as well, perhaps lag time and rate of digesta passage.