Ruminal Undegradable Protein Research Articles

Comparison of In Situ and In Vitro Techniques for Measuring Ruminal Degradation of Animal By-Product Proteins

Ruminally undegraded protein (RUP) values of blood meal (n = 2), hydrolyzed feather meal (n = 2), fish meal (n = 2), meat and bone meal, and soybean meal were estimated using an in situ method, an inhibitor in vitro method, and an inhibitor in vitro technique applying Michaelis-Menten saturation kinetics. Degradation rates for in situ and inhibitor in vitro methods were calculated by regression of the natural log of the proportion of crude protein (CP) remaining undegraded versus time. Nonlinear regression analysis of the integrated Michaelis-Menten equation was used to determine maximum velocity, the Michaelis constant, and degradation rate (the ratio of maximum velocity to the Michaelis constant). A ruminal passage rate of 0.06/h was assumed in the calculation of RUP. The in situ and inhibitor in vitro techniques yielded similar estimates of ruminal degradation. Mean RUP estimated for soybean meal, blood meal, hydrolyzed feather meal, fish meal, and meat and bone meal were, respectively, 28.6, 86.0, 77.4, 52.9, and 52.6% of CP by the in situ method and 26.4, 86.1, 76.0, 59.6, and 49.5% of CP by the inhibitor in vitro technique. The Michaelis-Menten inhibitor in vitro technique yielded more rapid CP degradation rates and decreased estimates of RUP. The inhibitor in vitro method required less time and labor than did the other two techniques to estimate the RUP values of animal by-product proteins. Results from in vitro incubations with pepsin-HCl suggested that low postruminal digestibility of hydrolyzed feather meal may impair its value as a source of RUP.

Effects of Supplementation of Energy or Ruminally Undegraded Protein to Lactating Cows Fed Alfalfa Hay or Silage

Alfalfa was harvested as silage or hay and fed in two 12-wk trials with a 4×4 Latin square design that used 12 (trial 1) or 24 (trial 2) multiparous lactating cows (4 ruminally cannulated cows per trial). Diets contained (dry matter basis) 75 or 50% alfalfa plus 24 or 40% high moisture corn (trial 1) or 50% alfalfa, 44 or 41% high moisture corn, with (3%) or without fish meal (trial 2). Experiments were conducted to evaluate the responses of cows fed alfalfa hay or alfalfa silage diets to an increase in protein supply from microbial protein synthesis (trial 1) or from the supplementation of ruminally undegraded protein (RUP) (trial 2). In trial 1, the increase in high moisture corn in the diet increased both milk protein and microbial crude protein yields (estimated from the excretion of purine derivatives) to a greater extent for the cows fed the alfalfa silage diets (170 and 337 g/d, respectively) than for the cows fed the alfalfa hay diets (100 and 100 g/d, respectively). In trial 2, RUP supplementation (as fish meal) increased milk protein yield 100 g/d for cows fed alfalfa silage diets and 20 g/d for cows fed alfalfa hay diets. These results indicated that protein status was poorer and, thus, more responsive to absorbable protein from microbial protein (trial 1) or RUP (trial 2) for cows that consumed alfalfa conserved as silage versus those that consumed alfalfa conserved as hay.

Relationships Between In Situ Protein Degradability and Grass Developmental Morphology

The objective of this research was to determine the relationships between the morphological development and in situ ruminally degradable protein (RDP), ruminally undegradable protein (RUP), and microbial protein of two cool season grasses (intermediate wheatgrass and smooth bromegrass) and two warm season grasses (switchgrass and big bluestem). The initial growth of grass tillers grown near Mead, Nebraska was clipped at ground level six times during the 1992 growing season and morphologically classified. Mean stage was calculated. Forage was ground to pass a 2-mm screen and was incubated in ruminally fistulated steers for 16h. The RUP was adjusted for microbial protein and acid detergent insoluble N. The mean stage of cool season grasses was higher than that of warm season grasses throughout the growing season. The RDP decreased as plant maturity increased for all species. The RUP expressed as a percentage of crude protein for the cool season grasses was lower than that for warm season grasses. The RUP for intermediate wheatgrass, smooth bromegrass, and switchgrass remained constant across maturities, but RUP for big bluestem decreased as maturity increased. Microbial augmentation of RUP decreased as crude protein decreased in all species. The RUP corrected for acid detergent insoluble N and microbial protein was relatively constant across plant maturities. The quantification of RUP across a range of plant maturities provided information for incorporating RUP content of forage grasses into the diets of animals.

Factors Affecting Body Tissue Mobilization in Early Lactation Dairy Cows. 1. Effect of Dietary Protein on Mobilization of Body Fat and Protein

Twenty Holstein cows were fed diets that were formulated with 16 or 19% crude protein (CP) that contained, respectively, 6 and 9% ruminally undegradable protein (RUP) (dry matter basis) to study the effect of increased RUP on tissue mobilization and production parameters. Cows were enrolled in the study from –14 to 114 d postpartum. Body composition measurements using the D2O dilution technique were made at –2, 5, and 12 wk postpartum. Maximum loss of body tissue occurred between wk 2 prepartum and wk 5 postpartum during which time cows fed both treatments mobilized a mean of 54kg of body fat and 21kg of body protein. Cows continued to mobilize 18kg of body fat through wk 12 postpartum, but the amount of body protein was unchanged. One unit of change in body condition score corresponded to about 40kg of empty body fat. Partitioning of empty body energy between empty body fat and protein indicated that, for each unit of change in body energy, 93% was lost or gained as body fat, and body protein accounted for only 7%. Increasing RUP in the diet had no effect on the postpartum amounts of empty body protein, empty body fat, or empty body energy. Milk production was 39.8kg for cows fed the 16% CP diet and 42.4kg for cows fed the 19% CP diet. There was an interaction of treatment by week postpartum. Both dry matter intake and milk production were lower during the first 6 wk postpartum but were greater thereafter for cows fed the 19% CP diet than for cows fed the 16% CP diet. Milk CP percentage was higher (3.08% vs. 2.89%), and milk CP yield tended to be greater (1.29 vs. 1.15 kg/d), for cows fed the 19% CP diet.

Lactational Performance of Cows Fed Low or High Ruminally Undegradable Protein Prepartum and Supplemental Methionine and Lysine Postpartum

Multiparous Holstein cows (n = 24) were fed diets containing 34 or 41% ruminally undegradable protein (RUP) for 30 d before parturition; then each group was fed a basal diet supplemented with or without ruminally stable Met (10.6 g/d) and Lys (15.2 g/d) for 75 d in the subsequent lactation. Supplementation of Met and Lys increased the milk yield of cows previously fed the low RUP diet, but milk yields before and after amino acid (AA) supplementation were similar for cows previously fed the high RUP diet. Milk protein content (percentage) increased from 2.83 to 2.96 for cows previously fed the high RUP diet. Milk protein yield increased from 1.13 to 1.21 kg/d when Met and Lys were fed. Data on AA concentration in plasma and AA extraction by the mammary gland suggest that the supplementation of Met and Lys corrected a Met limitation.According to the Cornell Net Carbohydrate and Protein System, the lactation diet was limiting for Met for maximum milk yield and was corrected by AA supplementation. Based on limiting AA, allowable milk yield was 42.5 kg/d, and the observed yield was 40.9 kg/d averaged across treatments. The group with the greatest allowable milk yield (45.2 kg/d) had the greatest actual milk yield (43.0 kg/d). The regression equation of observed milk yield on allowable milk yield was Y = 3.4 + 0.8805X.

Opioid-Mediated Responses of Dietary Protein on Reticular Motility and Plasma Insulin

Four ruminally and abomasally cannulated steers (603±22.7kg of body weight) were used to determine whether ruminally undegradable protein (RUP) would exert opioid-mediated effects on reticuloruminal motility or circulating concentrations of insulin. Steers were fed isonitrogenous diets (16% crude protein) containing either 30 or 40% RUP. The low RUP diet was supplemented with urea and soybean meal, and the high RUP diet was supplemented with blood meal, fish meal, corn gluten meal, and meat and bone meal. Diets contained 57% wheat silage and were fed twice daily at 0800 and 1600h. Experimental periods were 10 d in length. Blood samples were taken from jugular catheters, and reticular motility was measured at hourly intervals on d 10 over a 16-h period. Either naltrexone (0.5 mg/kg of body weight) or saline was infused into the abomasum at the second feeding (9h). Naltrexone reduced the frequency of reticular contractions by 16.5% for steers fed the low RUP diet. Naltrexone decreased the duration of reticular contractions by 9.3% for steers fed the low RUP diet and increased duration by 8.7% for steers fed the high RUP diet. Naltrexone decreased the opening time of the reticuloomasal orifice, expressed as a percentage of predose measurements, by 16.3% for steers fed the high RUP diet. Insulin was 21.3% higher with the high RUP diet. The postprandial rise in insulin decreased 36.7% with naltrexone. Dietary protein can exert effects mediated by opioids in ruminants.

Effect of Degradability of Dietary Protein and Fat on Ruminal, Blood, and Milk Components of Jersey and Holstein Cows

Twelve Holstein cows and 12 Jersey cows were used in six 4 × 4 Latin squares to investigate the effects of the degradability of dietary protein and supplemental dietary fat on milk components. Dietary dry matter contained 16% crude protein with two concentrations of ruminally undegradable protein (RUP) obtained by substituting blood meal for a portion of the soybean meal. Treatments were 1) 29% RUP, 0% added fat; 2) 29% RUP, 2.7% added fat (Ca soaps of fatty acids); 3) 41% RUP, 0% added fat; and 4) 41% RUP, 2.7% added fat. The dry matter of the total mixed ration fed at 1000 and 1400h consisted of 30% corn silage, 29% alfalfa haylage, and 41% concentrate. Supplemental dietary fat depressed dry matter intake by 6.2%. Plasma urea N was greater at 0700 and 1600h for Jerseys fed diets containing added fat and greater at 0700h for Holsteins fed diets containing 41% RUP than for Holsteins fed 0% added fat and 29% RUP. When averaged across both breeds, milk production increased 7.1%, and production of 4% fat-corrected milk by Jerseys increased 8.4%, in response to added dietary fat. Milk protein was reduced when Holstein diets contained 41% RUP. Milk protein content was reduced 7.1 and 3.9%, and milk urea N was increased 4.9 and 8.5%, by added fat and 41% RUP in both breeds, respectively. Added fat reduced the concentration, but not the yield, of milk components. Substitution of blood meal decreased the concentration and yield of milk protein and casein N.

Variation in ruminal degradation and intestinal digestion of animal byproduct proteins

In situ and in vitro procedures were used to determine ruminal degradation and intestinal digestion of crude protein (CP) from animal byproducts. Seven samples of meat and bone meal (MBM), hydrolyzed feather meal (HFM), ring dried blood meal (RBM), and batch dried blood meal (BBM) were obtained from various rendering and meat packing plants. Ruminal undegradable CP determined using in situ procedures ranged from 51.3 to 60.8% ( x ̄ = 55.4 ± 1.3% ), 53.6–87.9% ( x ̄ = 73.6 ± 3.8% ), 76.4–86.4% ( x ̄ = 81.0 ± 1.2% ), and 77.6–94.4% ( x ̄ = 84.3 ± 2.1% ), for MBM, HFM, RBM and BBM, respectively. Estimates of intestinal digestion of ruminal undegradable CP, determined using a three-step in vitro procedure, ranged from 40.9 to 70.1% ( x ̄ = 56.0 ± 4.0% ), 59.2–75.2% ( x ̄ = 65.3 ± 2.1% ), 72.0–90.3% ( x ̄ = 79.6 ± 2.5% ) and 28.8–79.2% ( x ̄ = 61.4 ± 6.8% ), for MBM, HFM, RBM, and BBM, respectively. Total intestinally absorbable dietary protein (IADP) was calculated as ruminal undegradable protein multiplied by intestinal digestion of the ruminal undegradable protein fraction. Intestinally absorbable dietary protein ranged from 21.6 to 39.3% ( x ̄ = 31.2 ± 2.7% ), 35.8–59.4% ( x ̄ = 47.6 ± 3.1% ), 57.5–75.2% ( x ̄ = 64.6 ± 2.6% ), and 24.8–62.7% ( x ̄ = 51.3 ± 5.3% ), for MBM, HFM, RBM, and BBM, respectively. Results demonstrate that large variations in ruminal degradation, intestinal digestion and IADP can occur among and within different rendering byproducts. These variations should be considered when determining the quality of animal byproducts as protein supplements for ruminants. Measurements of ruminal degradation and intestinal digestion of CP should be used by manufacturers to guarantee the quality of various batches of byproduct that are produced.

In vitro determination of ruminal protein degradation using freeze-stored ruminal microorganisms.

Mixed ruminal microorganisms were harvested from a lactating dairy cow and preserved frozen or lyophilized. Fermentation characteristics of freshly strained ruminal fluid, frozen microorganisms, or lyophilized microorganisms were evaluated during a 24-h pre-incubation and a 4-h incubation with test proteins. Differences observed during the first 4 to 6 h in total amino acid concentration, optical density, pH and VFA concentrations, acetate:propionate ratio, and lactate concentration largely disappeared later in the pre-incubation. Protein degradation rates determined for expeller and solvent meals were .015 and .092 h-1, .015 and .101 h-1, and .005 and .019 h-1, with fresh ruminal fluid, frozen microorganisms, and lyophilized microorganisms, respectively. Regression of degradation rates obtained with fresh ruminal fluid on those obtained with pre-incubated, frozen microorganisms indicated the two methods were well correlated (r2 = .98 and .94 in two experiments). Mean in vitro degradability obtained for 17 feeds using pre-incubated, frozen microbes was 89% of that obtained using the in situ method; however, in situ degradation rates for these same feeds averaged only 67% of those obtained using frozen microorganisms. Ruminal undegraded protein values for nine samples of heated soybeans and soybean meal, determined using frozen microbes, were overestimated relative to in vivo values (in vivo = 1.1 + .8 in vitro; r2 = .77). These results indicated that ruminal microorganisms can be preserved by freezing and used as the inoculum for in vitro determination of ruminal protein degradation after overnight pre-incubation.

Effect of ruminally undegradable protein from fish meal on growth and reproduction of peripuberal Brahman bulls1

Thirty-nine Brahman bulls (301.7 +/- 4.1 d; 202.7 +/- 4.7 kg) were allotted to one of two treatments and fed soybean meal (SBM)- or fish meal (FIS)-based supplements and hay to examine the effects of source of protein on growth and reproductive development. The fish meal supplement had 72% ruminally undegradable protein (RUP) and the soybean meal supplement had 47% RUP. Bulls assigned to the FIS treatment had higher (P < .01) total weight gain (81.2 +/- 1.4 vs 71.2 +/- 2.2 kg), higher (P < .01) ADG (.97 +/- .02 vs .85 +/- .03 kg), and better (P < .05) feed:gain ratio (7.6 +/- .1 vs 8.6 +/- .1 feed/BW gain for FIS vs SBM, respectively). Age at first motile spermatozoa was not affected (P > .05) by source of protein (429.9 +/- 9.6 vs 427.2 +/- 9.5 d, for bulls receiving FIS or SBM supplements, respectively). Likewise, age at puberty (473.3 +/- 21.7 d vs 465.9 +/- 12.9 d for bulls receiving FIS and SBM supplements, respectively) was similar for both treatment groups. There were no differences between treatments in scrotal circumference at those stages. At puberty semen quality was similar for bulls receiving FIS or SBM treatments, and no differences existed in LH and testosterone concentrations between treatments. We conclude that fish meal supplement increased growth but did not alter reproductive parameters in Brahman bulls.

Digestion and live-weight gain by beef cattle consuming bermudagrass supplemented with grain or different high-protein foodstuffs

ABSTRACTTwo experiments were made to determine the effects on digestion characteristics and live-weight (LW) gain of cattle consuming bermudagrass of supplementing with ground maize, soya-bean meal or a maizegluten— blood meal mix alone or maize plus the protein supplements. Experiment 1 was a Latin-square design with 14-day periods using six beef cows fitted with rumen and duodenal cannulas (490 kg). Cows were given bermudagrass hay at 12·7 g/kg LW alone (control, C) or with 2·4 g/kg LW of ground maize (M), 0·98 g/kg LW of soya-bean meal (S), 0·53 g/kg LW of maize-gluten plus 0·17 g/kg (dry matter basis) of blood meal (GB), M plus S (M + S) or M plus GB (M + GB). Nitrogen (N) intake was 106, 123, 143, 148, 166 and 166 g/day; total N at the duodenum was 101, 124, 117, 126, 140 and 161 (s.e. 5·91) g/day; and post-ruminal N disappearance was 61, 77, 72, 84, 87 and 110 (s.e. 5·6) g/day for C, M, S, GB, M + S and M + GB, respectively. In experiment 2, 96 crossbred beef heifers (203 kg LW) implanted with 200 mg testosterone and 20 mg oestradiol benzoate were allotted to 12 groups by LW (two groups per treatment). Heifers grazed bermudagrass paddocks for 84 days in two 42-day periods and supplement treatments were those in experiment 1. A period × treatment interaction in LW gain was noted (P&lt; 0·05). LW gain was 0·78, 0·81, 0·79, 0·76, 0·70 and 0·95 kg in period 1 and 0·46, 0·51, 0·56, 0·53, 0·64 and 0·61 kg in period 2 for C, M, S, GB, M + S and M + GB, respectively (s.e. 0·049). In conclusion, duodenal flow and post-ruminal disappearance of N were similar for the protein sources when offered singularly, but when given with maize values were greater for the mix of protein meals high in ruminal undegradable protein as compared with soya-bean meal. LW gain by heifer calves grazing bermudagrass was increased only by supplementation with ground maize plus the protein meal mix of low ruminal degradability.