Effect of fiber source and particle size on chick performance and nutrient utilization.

The addition of fiber in chick feeds is known to dilute nutrients; as a result, this may reduce nutrient digestibility and performance. However, recent studies suggest that moderate inclusion of insoluble fibers (2 to 3%) may stimulate gizzard development, which could result in better nutrient utilization and chick growth. The previous fiber sources evaluated were subject to wide fluctuation in their nutritional and chemical composition due to variation in processing. Miscanthus giganteus is a C4 grass purposefully grown for its fiber content which has a consistent fiber composition compared to food process residues. The objectives of this study were to determine the effect of dietary fiber source and particle size on day-old chick performance and nutrient digestibility. Day-old chicks (8 chicks per cage, 5 cages per treatment) were fed diets containing 3% of either sepiolite (SEP), cellulose (CEL), coarse beet pulp (BP), fine BP, coarse Miscanthus grass (MG), and fine MG. At the end of days 7, 14, and 21, chicks and experimental diets were weighed to compute average daily gain and feed intake. In addition, excreta from the previous 48 h of each data capture point was collected to determine nutrient digestibility. In general, chicks fed diets containing fiber consumed more feed, gained more weight, and had better feed conversion rate than birds fed the SEP diet. Particle size of the fiber had no effect on chick performance; however, nutrient utilization was higher (P < 0.05) for chicks fed coarse fiber particles compared to these fed fine fiber particles. Birds fed diets containing MG performed similar to chicks fed CEL (P > 0.05), but digestibility coefficients of birds fed BP diets were generally higher than chicks fed MG diets. In conclusion, chicks performed better with fiber in their diet and MG was comparable to CEL.

The amino acid composition and protein quality of various egg, poultry meal by-products, and vegetable proteins used in the production of dog and cat diets.

New protein ingredients are used to support pet food market growth and the development of new products while maintaining animal dietary needs. However, novel protein sources (e.g., spray-dried chicken, and (or) rice, pea, and potato protein concentrates) have limited data available regarding their protein quality. The objective of this study was to evaluate protein ingredients used in the pet food industry by laboratory analysis and a chick growth assay as a model. Following analysis for proximate and amino acid composition, chicks (six birds per pen with four pens per treatment) were fed experimental diets for 10 d. Diets contained 10% crude protein from each of the experimental protein sources (spray-dried egg-SDEG; spray-dried egg white-SDEW, spray-dried inedible whole egg-SDIE, chicken by-product meal-CBPM, chicken meal-CKML, low-temperature fluid bed air-dried chicken-LTCK, low-temperature and pressure fluid bed dried chicken-LTPC, spray-dried chicken-SDCK, whey protein concentrate-WPCT, corn gluten meal-CGML, corn protein concentrate-CPCT, potato protein isolate-PPIS, rice protein concentrate-RPCT, pea protein isolate-PEPI, soy protein isolate-SPIS, and soybean meal-SBML) along with an N-free diet (negative control). Chicks fed SDEG, SDIE, and LTPC had the highest protein efficiency ratio (PER; P < 0.0001; 5.18, 5.37, and 5.33, respectively), LTCK and SDCK were intermediate (4.54 and 4.79), and the CBPM and CKML were the lowest among the poultry proteins for EAA:NEAA, PER, and Lys availability. Among the vegetable proteins, PPIS and SBML had the highest PER values (3.60 and 3.48, P < 0.0001). In general, the chick PER method ranked the quality of animal protein sources higher than vegetable proteins, and these results were consistent with the EAA:NEAA ratio and Lys availability.

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.

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.

Effects of species raw material source, ash content, and processing temperature on amino acid digestibility of animal by-product meals by cecectomized roosters and ileally cannulated dogs.

We conducted experiments to determine amino acid (AA) digestibility of nine animal by-product meals using precision-fed cecectomized roosters and ileally cannulated dogs. The products initially evaluated in roosters were meat and bone meals (MBM) containing 24 or 34% ash, poultry by-product meals (PBP) containing 7 or 16% ash, lamb meals (LM) containing 15 or 24% ash, a LM analog containing a mixture of LM and turkey meal, and two MBM processed at either a low or high temperature. The MBM and PBP differing in ash, low-ash LM, and low-temperature MBM then were incorporated into extruded dry dog foods and evaluated in cecectomized roosters and ileally cannulated dogs. True digestibility of total AA in roosters averaged 76% for the nine meals fed alone, with the low-temperature MBM being highest at 84% and the low-ash LM being lowest at 66% (P < .05). No consistent differences in rooster AA digestibility were observed between pairs of meals differing in ash content. Digestibilities of AA were higher in the low-temperature MBM than in the high-temperature MBM. Differences in rooster AA digestibility values among the six extruded dog foods containing selected animal meals were similar to those observed when the animal meals were fed alone. The ileally cannulated dog assay yielded results for AA digestibilities that were highly correlated (r = .87 to .92) with those of the rooster assay, whereby the high-ash MBM and low-temperature MBM foods had the highest mean AA digestibility at 82% and the low-ash LM food had the lowest mean AA digestibility at 62% (P < .05). Again, no consistent differences in AA digestibilities for dogs were observed between pairs of dog foods containing MBM or PBP differing in ash content. Results of this study indicated that processing temperature influenced AA digestibility of MBM, but species raw material source and ash content had no consistent effect on AA digestibility. Results also indicated that the precision-fed cecectomized rooster assay could be used to predict differences in AA digestibility among animal by-product meals for dogs.

Assessment of postruminal amino acid digestibility of roasted and extruded whole soybeans with the precision-fed rooster assay.

The objectives of these studies were to predict the effects of roasting and extrusion temperatures of whole soybeans (SB) on intestinal protein digestibility in cattle. Intestinal digestibility was assessed with a two-stage in vitro or in situ ruminal incubation/precision-fed cecectomized rooster bioassay. In Exp. 1, whole SB (raw SB or SB roasted to 141, 149, or 157 degrees C exit temperature from a commercial roaster and steeped for 30 min) were incubated in strained ruminal fluid and McDougall's buffer (50:50) at 39 degrees C for 16 h. In Exp. 2, SB (ground raw SB or SB extruded at 116, 138, or 160 degrees C) were placed in polyester bags (20 x 30 cm) and suspended in the ventral rumen of steers for 16 h. Lyophilized residue of the in vitro or in situ incubations and samples of raw SB and most extensively heated SB (roasted SB at 157 degrees C or extruded SB at 160 degrees C) for each respective experiment were crop-intubated to cecectomized roosters. Total excreta were collected for 48 h after intubation and lyophilized, and amino acid (AA) concentrations were determined. In Exp. 1, total AA digestibility was 61.6 and 84.5% for unincubated whole raw SB and 157 degrees C roasted SB, respectively, and 66.2, 88.9, 91.3, and 91.6% for in vitro residues of whole raw SB and SB roasted at 141, 149, and 157 degrees C, respectively. Trypsin inhibitor (TI) activity was 20.09, 1.69, 1.54, and 1.84 mg/g fat-free DM for unincubated whole raw SB and 141, 149, and 157 degrees C roasted SB, respectively, and 30.84, 1.01, .90, and .26 mg/g fat-free DM for in vitro residues of whole raw SB, 141, 149, and 157 degrees C roasted SB, respectively. In Exp. 2, total AA digestibility was 68.5 and 87.7% for unincubated ground raw SB and 160 degrees C extruded SB, respectively, and 81.9, 91.3, 89.7, and 89.4% for in situ residues of ground raw SB and 116, 138, and 160 degrees C extruded SB, respectively. Trypsin inhibitor activity was 17.61, 4.89, 4.08, and 1.56 mg/g fat-free DM for unincubated ground raw SB, 116, 138, and 160 degrees C extruded SB, respectively, and 3.62, .59, .55, and .21 mg/g fat-free DM for incubated ground raw SB, 116, 138, and 160 degrees C extruded SB, respectively. Heat treatment by roasting and extrusion improved AA digestibilities of SB, but there were no differences detected among the roasting or extrusion temperatures. Ruminal fermentation did not eliminate the negative effects of TI activity on intestinal digestibility of AA in whole SB but did reduce TI activity in ground SB.

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.

The effect of roasting temperature applied to whole soybeans on site of digestion by steers: I. Organic matter, energy, fiber, and fatty acid digestion.

A 4 x 5 Youden square design was used to determine the effects of form of oil and roasting temperature of soybeans on site and extent of OM, fiber, energy, lipid, and fatty acid digestion and the degree of ruminal biohydrogenation of C18 unsaturated fatty acids. Four steers (373 kg +/- 30.7) with ruminal, duodenal, and ileal cannulas were fed each of five diets during five periods. Diets contained (percentage of DM) corn silage (50%), alfalfa hay (24%), and a corn-urea concentrate (6%). Cornstarch grits (4%) and whole full-fat soybeans (16% of diet DM), raw or roasted to an exit temperature of 141 degrees, 149 degrees, or 157 degrees C in a commercial roaster, constituted the remainder of the RAW, 141, 149, and 157 treatments. Soybean oil equivalent to the quantity in the whole soybeans (3.4% of diet DM) and corn starch grits (16.6% of diet DM) constituted the basal treatment. Diets provided 6.0% ether extract (EE) and 4.6 Mcal of GE/kg of DM. Flows of nutrients were determined by reference to Cr2O3 as an external marker. Ruminal pH, molar proportions of acetate and butyrate, and total ruminal VFA (mM) were not affected by treatment. Ruminal digestibilities of OM, GE, EE, NDF, and ADF were not different among treatments (average 49.5, 41.7, -3.6, 47.4, and 50.1%, respectively). Small intestinal disappearances of OM, GE, and EE were not different among treatments (average 18.4, 24.8, and 61.6% of intake, respectively). Overall, C18:0, C18:1, C18:2, and C18:3 acids averaged 4.4, 25.3, 60.6, and 8.5% of total C18 fatty acids in the diet, respectively; digesta at the duodenum contained 79.0, 16.5, 4.4, and .2%, respectively. The unsaturated C18 fatty acids of soybean oil from whole soybeans, regardless of roasting temperature, were hydrogenated to a similar degree as free soybean oil in the basal diet (average 78.0%). Small intestinal digestibility of total fatty acids was greater (P = .04) for roasted than for raw soybeans (70.9 vs 60.4%). Total tract digestibilities of total C18 fatty acids and total fatty acids were greater (P = .01) for roasted soybeans than for raw soybeans (88.0 vs 82.4 and 86.3 vs 81.0%, respectively). Total tract apparent digestibility of energy was lower (P = .07) for the basal diet than for soybean-containing diets (69.2 vs 70.0%, respectively). Diets containing whole soybeans, regardless of roasting temperature, or free SB oil had similar effects on ruminal characteristics and nutrient digestion.(ABSTRACT TRUNCATED AT 400 WORDS)

The effects of roasting temperature applied to whole soybeans on site of digestion by steers: II. Protein and amino acid digestion.

A 4 x 5 Youden square design was used to determine the effect of roasting temperature of whole soybeans on escape of CP from the rumen and disappearance of N from the small intestine in steers. Four steers (average BW 373 kg +/- 30.7) cannulated at the rumen, duodenum, and ileum were fed each of five diets (1.8% of BW) over five periods. The basal diet contained corn silage (50% of diet DM), alfalfa hay (24%), corn-urea premix (6%), corn starch grits (16.6%), and soybean oil (3.4%). Soybeans (16% of diet DM), either raw or heated to an exit temperature of 141, 149, or 157 degrees C in a commercial roaster, replaced the soybean oil and most of the corn starch grits in the soybean-containing diets. Ruminal ammonia N was lower (P < .05) for the basal diet than for the soybean-containing diets. Roasting temperature of whole soybeans had no significant impact on ruminal ammonia N. Total N reaching the duodenum was greater (P < .05) for steers fed the soybean diets than for steers fed the basal diet. Non-bacterial N (dietary N) at the duodenum was increased (P < .05) by feeding soybeans. Soybean N reaching the duodenum decreased with increased roasting temperature. Increased roasting temperature of whole soybeans seemed to make the soybeans more brittle, subsequently increasing degradation of CP in the rumen. However, disappearance of soybean N in the small intestine, as a proportion of the soybean N entering the small intestine, increased with increased roasting temperature. Apparent total tract N digestibility was increased (P < .05) by feeding soybeans. Flow to the duodenum and small intestinal digestibility of total, essential, and nonessential amino acids increased (P < .05) when soybeans were fed and when roasted vs raw soybeans were fed. Under normal roasting conditions, it seemed that little potential for heat damage to the soybean protein existed. Instead, undesirable effects of heating on handling characteristics of the soybeans were reached before the point at which loss of nutritive value occurred. Feeding steers diets containing roasted whole soybeans increased the N and amino acids available to steers over steers fed diets containing raw soybeans due to increased ruminal soybean nitrogen escape and increased small intestinal digestibility.

Effect of roasting on site and extent of digestion of soybean meal by sheep: I. Digestion of nitrogen and amino acids.

Six mature wethers (BW 72 kg) with ruminal, duodenal, and ileal cannulas were fed a control (no added soybean meal [SBM]) diet or diets containing unheated SBM or SBM roasted at 165 degrees C for 75, 150, 180, or 210 min in a 6 x 6 Latin square experiment. Concentrations of indicators of heat exposure (ADIN, ADF, NDF) in SBM increased with increasing roasting time. Duodenal flows of total N, non-bacterial N, and SBM N increased (P < .05) linearly with increased roasting time. Small intestinal (SI) digestibility (percentage entering SI) of total N and SBM N was influenced quadratically (P < .05) by roasting time; SI digestibilities were modestly increased by heating SBM to 150 min, then declined dramatically when SBM was heated for 180 and 210 min. These responses resulted in a quadratic (P < .05) increase in quantity of total and SBM N disappearing in the SI; quantities increased as SBM was heated to 150 min and remained unchanged when SBM was heated for 180 and 210 min. These responses resulted in a quadratic (P < .05) increase in quantity of total and SBM N disappearing in the SI; quantities increased as SBM was heated to 150 min and remained unchanged when SBM was heated for 180 and 210 min. Duodenal flows and SI digestibilities of total and non-bacterial amino acids (AA) and of most individual AA followed patterns similar to those observed for N. Maximum quantities of total and individual AA disappeared from the SI when wethers were fed SBM roasted at 165 degrees C for 150 min. Evaluation of the effects of heat treatment on the nutritive value of a protein source for ruminants should include considerations for both ruminal protein escape and SI availability of escaped protein and for the nature of the AA supply absorbed from the SI.

Effect of roasting on site and extent of digestion of soybean meal by sheep: II. Digestion of artifacts of heating.

Six mature wethers (BW 72 kg) with ruminal, duodenal, and ileal cannulas were fed a basal (no added soybean meal [SBM]) diet or diets containing unheated SBM or SBM roasted at 165 degrees C for 75, 150, 180 or 210 min in a 6 x 6 Latin square experiment. Concentrations of indicators of heat exposure (NDF, ADF, and ADIN) in SBM increased with increasing roasting time. Organic matter digestion characteristics were not affected (P > .05) by supplementation or roasting of SBM. Daily intakes of NDF, ADF, and ADIN were higher (P < .05) when wethers were fed SBM-containing diets than when they were fed the basal diet and also were higher (P < .05) when wethers were fed diets containing roasted SBM than when fed the diet containing unheated SBM. Roasting time of SBM had a quadratic effect (P < .05) on intakes of NDF, ADF, and ADIN, with the lowest intakes observed for diets containing unheated SBM or SBM roasted for 75 min and the highest intakes observed for diets containing SBM roasted for 180 or 210 min. Disappearance of ADF in the stomach (grams per day) was not affected by supplementation or roasting of SBM. Disappearance of NDF and ADIN in the stomach (grams per day) were higher (P < .05) when wethers were fed SBM-containing diets than when they were fed the basal diet and also were higher (P < .05) when wethers were fed diets containing roasted SBM than when they were fed those containing unheated SBM.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of endophyte-infected tall fescue consumption and use of a dopamine antagonist on intake, digestibility, body temperature, and blood constituents in sheep.

Two experiments were conducted with lambs that consumed endophyte-infected (Acremonium coenophialum) tall fescue diets under elevated temperature and humidity and supplemented with the dopamine antagonist metoclopramide (M). In Exp. 1, 12 ruminally cannulated wethers (average weight 49 kg) were allotted by weight to either an endophyte-free diet (E-) or endophyte-infected diet (E+; 1,170 ppb of ergovaline), or E+ supplemented with M (15 mg/kg of lamb BW; E+M). Ad libitum DM intake and digestibility were lower (P < .05) for E+ than for E- diet. Supplementation of E+ with M increased (P < .05) DM intake by 27.6% but did not change DM digestibility. Body temperature increased (P < .05) when lambs consumed E+ and was further increased when M was supplemented. For Exp. 2, 19 wether lambs (average weight 24 kg) were allotted to treatments to evaluate the effects of endophyte consumption (0 vs 2,430 ppb of ergovaline) and supplementation with M (0 vs 20 mg/kg BW). An interaction (P < .05) of main effects was measured for DM intake. Lambs that consumed E+M consumed more DM than did lambs fed only E+, but lambs offered the E- diet and supplemented with M did not increase DM consumption. Diet DM digestibility was not different among treatments. Skin vaporization decreased (P < .05) due to E+ consumption and M supplementation. The concentration of prolactin in plasma was decreased (P < .05) by consumption of E+ (8 vs 136 ng/mL) and did not increase due to M supplementation.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of endophyte-infected tall fescue consumption on diet utilization and thermal regulation in cattle.

Two experiments were conducted to determine the effects of endophyte fungus (Acremonium coenophialum) ingestion in tall fescue diets and environmental temperature on heat dissipation and diet utilization by cattle. In Exp. 1, 12 Angus heifers (average weight 244 kg) were allotted by weight to either an endophyte-free (E-) or endophyte-infected (E+; 381 ppb of ergovaline) diet. Environmental temperature varied between 22 and 32 degrees C. Voluntary DM and water intakes were similar (P > .10) among treatments. Rectal temperatures and concentrations of prolactin in plasma were lower (P < .05) after ingestion of the E+ diet. Plasma triiodothyronine, thyroxine, and cortisol concentrations were not affected by diet. In Exp. 2, 24 Holstein steers (average weight 114 kg) were allotted by weight to either E- or E+ (285 ppb of ergovaline) and one of two environmental temperatures (22 or 32 degrees C). At 32 degrees C, feed intake was reduced by 22%, and water consumption was increased by 62% compared with steers housed at 22 degrees C. Consumption of E+ reduced feed intake by 10% but did not influence water consumption. Plasma concentration of prolactin was decreased (P < .05) within 48 h after consumption of E+. Rectal temperatures increased in response to both environmental temperature (P < .05) and E+ consumption (P = .06). Digestibilities of DM and OM for E+ were 9% lower (P < .05) than for E-.(ABSTRACT TRUNCATED AT 250 WORDS)

Performance, forage utilization, and ergovaline consumption by beef cows grazing endophyte fungus-infected tall fescue, endophyte fungus-free tall fescue, or orchardgrass pastures.

Two 120-d trials (May to September, 1988 and 1989) determined the effects of grazing tall fescue (two varieties) or orchardgrass on forage intake and performance by beef cows. Each summer, 48 cow-calf pairs grazed endophyte-infected Kentucky-31 tall fescue (KY-31), endophyte-free Mozark tall fescue (MOZARK), or Hallmark orchardgrass (OG) pastures (16 pairs/treatment). Forage OM intakes and digestibilities were determined during June and August each year. Cow and calf BW and milk production were determined every 28 d. During June of both years, OM intakes did not differ (P greater than .10) among treatments. During August of 1988, intakes were 18% lower (P less than .05) by KY-31 cows (1.6% of BW) than by MOZARK or OG cows (average 1.95% of BW); however, no differences (P greater than .10) were measured in August of 1989. Estimates of ergovaline consumption during June from KY-31 were between 4.2 (1988) and 6.0 mg/d (1989), whereas August estimates were between 1.1 (1988) and 2.8 mg/d (1989). Ergovaline in MOZARK estrusa was below detection limits, except in August of 1989. Cows that grazed KY-31 lost three times (P less than .01) more BW than cows that grazed MOZARK or OG (42 vs 9 and 13 kg, respectively). Milk production by KY-31 cows was 25% lower (P less than .01) than that by cows that grazed MOZARK or OG (6.0 vs average of 8.0 kg/d). Similarly, slower (P less than .01) calf gains were noted for KY-31 than for MOZARK or OG (.72 vs .89 and .88 kg/d, respectively). Cows grazing KY-31 experienced accelerated BW loss and reduced milk production and weaned lighter calves than did cows grazing MOZARK or OG. Decreased performance was not explained by consistently reduced forage intakes; hence, altered nutrient utilization was suspected.