The influence of timing and the addition of urea to supplements containing DL-methionine on ruminal fermentation and cow weight change in beef cows.

A study was conducted to determine an optimal time for supplementation of DL-methionine in relation to time of forage intake by mature British breed-type crossbred cows, and two other experiments were conducted to determine whether ruminal ammonia concentration limited changes in disappearance rates in situ and ruminal functions caused by supplements containing DL-methionine. Experiments 1 and 2 used 4 x 4 Latin square designs with four cows in each experiment. Treatments in Exp. 1 were no supplement (CON), DL-methionine at feeding (0800), DL-methionine 4 h after feeding (1200), and DL-methionine 7 h after feeding (1500). Treatments in Exp. 2 were .5 kg of beet pulp (CON), .5 kg of beet pulp plus 16.5 g of DL-methionine (MET), .5 kg of beet pulp plus 16.5 g of DL-methionine and 55 g of urea (METU), and .4 kg of soybean (SOY). Experiment 3 was conducted in a 326-ha pasture with treatments of no supplement (CON), .5 kg of beet pulp plus 12.5 g of DL-methionine and 30 g of urea (METU), and .4 of kg soybean meal (SOY). In Exp. 1, in situ NDF disappearance rates of cows supplemented at 1200 and 1500 were greater (P less than .01) than those of cows supplemented at 0800. In Exp. 2, ruminal ammonia concentration was greatest (P less than .001) for METU (5.2 mg/dl) and least for CON (1.5 mg/dl). Disappearance rates in situ for DM differed (P less than .01) among treatments; METU was similar (P greater than .2) to SOY but faster (P less than .01) than MET. Disappearance rates of NDF were greatest (P less than .001) for METU-supplemented cows. In Exp. 3, DM and NDF disappearance rates were faster (P less than .10) for SOY than for METU. Cow BW change was positive for METU and SOY, and decrease in condition score was least (P less than .10) for METU- and SOY-treated cows. These studies indicate favorable ruminal responses to DL-methionine supplementation; however, the response depended on time of supplementation and ruminal ammonia concentration.     

Escape protein for beef cows: I. Source and level in corn plant diets

Two gestating cow winter grazing trials and two lactating cow drylot trials were conducted to evaluate the use of a slowly degraded protein source in corn plant diets for mature beef cows. Gestating beef cows grazing cornstalks were supplemented with .86 kg/(cow.d) of a 20% crude protein equivalent (CPE) pellet (DM basis). In Trial 1 cows fed diets containing 80% dehydrated alfalfa meal (high DEHY) gained more weight (P less than .05) than those fed diets containing 40% dehydrated alfalfa meal (low DEHY) or urea but not more than the cows fed soybean meal (SBM); however, no differences among treatments were observed in Trial 2. Four lactation diets composed of ground corncobs and corn silage were supplemented with either urea, SBM, or two levels of dehydrated alfalfa meal (DEHY) as N sources. The same amount of supplemental N was fed in both trials, consisting of .31 kg of natural protein for the SBM and low DEHY treatments or .42 kg for high DEHY. Ammoniated corncobs replaced 35% of the ground corncobs in Trial 4. Diets were calculated to contain (DM basis) 55% TDN and 9% CPE in Trial 3 and 11% CPE in Trial 4. In Trial 3, lactating cows supplemented with DEHY gained more weight (P less than .10) than those fed the urea supplement but not more than those fed SBM. Gains by cows fed the urea- and SBM-supplemented diets were not different (P greater than .10). Cow weight gains in Trial 4 were not affected by type of protein supplementation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of DL-methionine supplementation on growth, ruminal fermentation and dilution rates in heifers

A 3 X 3 replicated Latin square design was used to evaluate three isonitrogenous supplements designed to supply 250 g crude protein (CP) daily. Measurements included in situ dry matter (DM) and neutral detergent fiber (NDF) fermentation and ruminal dilution rates. Supplements contained beet pulp plus DL-methionine and urea (MET), ammonium sulfate and urea (U) or soybean meal (SBM). Six mature, ruminally cannulated crossbred beef cows were individually fed supplement and a mixture (63% NDF and 6.1% CP) of chopped 75% grass hay and 25% barley straw in ad libitum. Fermentation rate of DM was increased (P less than .05) by 30% with MET in comparison to SBM or U (9.54 vs 7.28% and 7.74%/h for MET, SBM and U, respectively). Even though MET improved fermentation rate by 30%, particle dilution rate was more important in affecting ruminal digestibility than fermentation rate. Two 90-d heifer growth trials were conducted to evaluate similar supplements. Supplements similar to those used in the in situ trial were mixed with roughage to provide a complete diet balanced for .3 kg daily gain. Heifers consumed 112% of the National Research Council CP requirement. Weight gain, intake and feed conversion were similar (P greater than .10) for all treatments. In heifer trial 2, 90% of the National Research Council CP requirement was fed. The heifers supplemented with MET and SBM had faster (P less than .05) weight gains than heifers receiving U. These studies show that feeding DL-methionine with urea, as compared with feeding an isonitrogenous supplement containing SBM, increased the fermentation rate of DM.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effects of ruminal escape protein or fat on nutritional status of pregnant winter-grazing beef cows

This study was designed to determine the influence of soybean meal supplementation, with or without additional ruminal escape protein or fat, on the nutritional status of pregnant winter-grazing beef cows. During two winters (Trials 1 and 2), approximately 60 prepartum beef cows grazed native foothills range each year. Cows were allotted randomly to five groups and supplemented (g/d) with either none (control); 570 soybean meal (SOY); 450 soybean meal plus 230 blood meal (SOY + BM); 140 soybean meal, 16 urea plus 450 corn gluten meal (SOY + CGM); or 570 soybean meal plus 210 animal fat (SOY + FAT). These supplements were designed to supply similar quantities of ruminal degraded protein while varying in escape protein quantity and source (SOY + BM and SOY + CGM). Condition scores and body weights were determined at trial initiation (mid-December) and conclusion (early March). Eight blood samples obtained over 4 d during three periods (9, 4 and 1 wk prior to parturition) were analyzed for concentrations of glucose, urea nitrogen (N), total bilirubin, creatinine, albumin, total protein and cholesterol. Cows in the control treatment experienced the greatest BW loss in both trials. In Trial 2, escape protein tended to decrease (P less than .06) BW loss compared to SOY, though loss tended to be greater (P less than .08) with SOY + CGM than with SOY + BM. Escape protein can enhance nutritional status when supplemented with .6 kg/d of soybean meal.     

Influence of supplemental nitrogen source on digestion of nitrogen, dry matter and organic matter and on in vivo rate of ruminal protein degradation

Seven Holstein steers (340 kg) fitted with ruminal, duodenal and ileal cannulae were used to measure the influence of supplemental N source on digestion of dietary crude protein (CP) and on ruminal rates of protein degradation. Diets used were corn-based (isonitrogenous, 12% CP on a dry matter basis, and isocaloric, 80% total digestible nutrients) with urea, soybean meal (SBM), linseed meal (LSM) or corn gluten meal (CGM) as supplemental N. Ruminal ammonia N concentrations were higher (P less than .05) in steers fed LSM than in those fed CGM, but did not differ from those in steers fed urea or SBM (11.7, 6.7, 9.1 and 9.2 mg/100 ml, respectively). Due to the high degradability of urea, ruminal digestion of dietary CP was greater (P less than .05) in steers fed urea than in those fed CGM, but intermediate in steers fed SBM and LSM (58.4, 48.8, 53.1 and 53.9%, respectively). Flow of bacterial nonammonia N to the duodenum was highest (P less than .05) in steers fed SBM or LSM, intermediate (P less than .05) for urea and lowest (P less than .05) for CGM (86.8, 86.1, 76.3 and 65.9 g/d, respectively). Efficiency of bacterial protein synthesis was lowest in steers fed CGM and differed (P less than .05) from SBM (15.6 vs 21.8 g N/kg organic matter truly digested, respectively). Rate of ruminal digestion for SBM-CP differed (P less than .05) from that of CGM-CP but not from that of LSM-CP (17.70, 5.20 and 10.13%/h, respectively). The slow rate of ruminal degradability of CGM resulted in increased amounts of dietary protein reaching the intestinal tract but lower amounts of bacterial protein, thus intestinal protein supply was not appreciably altered.     

Fish meal as a protein supplement in finishing lamb diets

An in situ protein degradation trial and two growth trials were conducted to evaluate the use of fish meal (FM) as a protein supplement in feeder lamb diets. Finn cross and Hampshire lambs were given ad libitum access to corn diets, minerals, and water. In Growth Trial 1, four isonitrogenous (12.6% CP on a DM basis) and isocaloric (77% TDN) diets were supplemented with the following: a) 100% soybean meal (SBM); b) 70% SBM + 30% FM; c) 40% SBM + 60% FM; and d) 100% FM on a DM basis. Diets were fed to 144 lambs for 56 d in a randomized complete block (initial BW) design. In Growth Trial 2, four diets were fed to 80 lambs for 42 d in a completely randomized design with treatments arranged as a 2 x 2 factorial. Main effects in Growth Trial 2 were dietary CP level (13.3 or 14.9%) and source (SBM or SBM + FM). Alfalfa hay was used as the roughage part of each diet. In situ CP degradation (determined in cattle) of SBM, FM, and corn fed in both growth trials were 77.8, 52.3, and 56.8%, respectively. In neither growth trial was ADG affected (P greater than .05) by dietary CP source. Lambs gained faster (P less than .05) when the CP level was increased from 13.3 to 14.9% in Growth Trial 2. In both trials, protein efficiency ratio (grams of gain/grams of protein intake) and energy efficiency ratio (grams of gain/kilograms of TDN intake) were not different (P greater than .05) among diets. Because of the low ruminal degradation of corn protein, the relative value of SBM and FM in full-fed, high-corn diets was comparable.     

Influence of protein degradability in range supplements on abomasal nitrogen flow, nitrogen balance and nutrient digestibility

Two metabolism trials were conducted with yearling steers fed mature native forage to measure the effect of supplemental protein degradability on selected metabolic variables. Supplements contained 40% crude protein equivalence. In Trial 1, four abomasal-cannulated steers weighing 290 to 379 kg were fed supplements containing the following N sources: (1) 15% corn, 85% urea (U); (2) 100% soybean meal (SBM); (3) 10% corn, 40% soybean meal, 50% urea (SBM-U) and (4) 14% corn, 36% blood meal, 50% urea (BM-U). Equal portions of the daily diet (2.2% of body weight) were fed every 2 h. Treatment differences were not significant for organic matter digestibility, abomasal organic matter flow, nonammonia N flow, feed N flow, bacterial N flow and efficiency of microbial protein synthesis. There was a positive (P less than .05) relationship between quantity of slowly degraded protein fed and nonammonia N flow (r = .97) or feed N flow (r = .98). Escape N was determined to be 21.5, 16.5 and 54.2% in SBM, SBM-U and BM-U supplements, respectively. In the second trial, no supplement, SBM, SBM-U and BM-U were fed in a N balance trial. Dry matter, crude protein and neutral detergent fiber digestibilities were higher (P less than .05) for steers fed supplemented diets. Acid detergent fiber digestibility was higher (P less than .05) for steers supplemented with SBM than steers fed the unsupplemented diets. Nitrogen retention was greater (P less than .05) for cattle fed SBM and BM-U than for cattle fed SBM-U or no supplement.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of defaunation and various nitrogen supplementation regimens on microbial numbers and activity in the rumen of sheep

Five sheep (average BW 62 kg) were fed 65% roughage: 35% concentrate diets (CP = 15%) in a 5 x 5 Latin square design to study the effects of combinations of defaunation and N supplements (soybean meal [SBM], corn gluten meal [CGM], blood meal [BM], urea, and casein) differing in ruminal degradation on ruminal microbial numbers and activity. Diets were fed twice daily (DM intake 1,759 g/d). Defaunation was accomplished with doses of 30 ml of alkanate 3SL3.sheep-1.d-1 for 3 d with 2 d of fasting. Treatment 1 (control) involved feeding faunated sheep a diet in which the supplemental N was 67% SBM N and 33% urea N. Treatment 2 involved feeding defaunated sheep the same diet as the control. Treatments 3, 4, and 5 involved feeding defaunated sheep diets in which the supplemental N source was either 67% CGM-BM N (CGM and BM combined on a 1:1 N ratio): 33% urea N, or 33% CGM-BM N:67% urea N or 33% CGM-BM N:33% urea N:33% casein N, respectively. Compared with the faunated control, defaunation (Treatments 2, 3, 4, and 5) increased (P less than .05) total direct counts of ruminal bacteria (2.7 vs 1.3 x 10(11)/ml), fungal zoospores (2.8 vs 1.4 x 10(5)/ml), and ruminal microbial protease activity (1.4 vs 1.0 mg azocasein/[ml ruminal fluid.h]). Defaunation did not have a consistent effect on ruminal microbial deaminase activity. Compared with the control, defaunation resulted in lower (P less than .05) total perchloric acid-soluble amino N in ruminal fluid at 4 and 10 h after the morning feeding. Defaunation did not decrease (P greater than .05) total free amino acid concentrations in ruminal fluid, but it altered the profile of free amino acids. Although defaunation increased (P less than .05) ruminal bacterial numbers, no increases in total microbial CP or OM concentrations in ruminal contents were observed.     

Evaluation of various nitrogen supplements in starter diets for growing Holstein steers and their effects on ruminal bacterial fermentation in continuous culture

Concurrent in vivo and in vitro studies were conducted to evaluate urea (U), soybean meal (SBM), ground soybeans (RAW), extruded soybeans (ES) or extruded soybeans plus urea (ES + U) as primary supplemental N sources in starter diets for Holstein steers. Three groups of 48 Holstein steers each were fed five different starter diets to 181 kg BW in three experimental periods over 2 yr. Average daily gains were similar (P greater than .05) for steers fed ES + U (1.12 kg), ES (1.08 kg) and SBM (1.09 kg) but lower (P less than .05) for those fed U (1.00 kg) or RAW (.97 kg) diets. Feed/gain was similar (P greater than .05) for ES-fed steers vs those fed other diets except U. From 181 to 477 kg, all steers were fed the same diet. Steers fed the RAW starter diet had the lowest (P less than .05) ADG for the entire period. The starter diets were used as substrates for ruminal microbial metabolism in eight dual-flow continuous culture fermenters. True OM digestion was higher and NDF and ADF digestion was lower (P less than .05) for the ES + U diet than for the ES diet. Dietary protein degradation was lowest (P less than .05) for the ES diet (64.4%). Total bacterial N flow was higher (P less than .05) with the ES + U, SBM and U diets than with the ES diet. Lysine flow was higher (P less than .05) for the ES + U diet than for all other diets except ES. Results of these experiments indicate that ES as a protected ruminal escape N source with or without added urea did not improve steer performance above that obtained from SBM in starter diets.     

Hydrolyzed feather meal as a protein source for growing calves

Growth, digestion and in situ studies were conducted to determine the protein value of hydrolyzed feather meal (Fth) for growing ruminants. Dacron bags containing blood meal (BM), Fth, corn gluten meal (CGM) and soybean meal (SBM) were suspended in the rumen of two steers for 12 h to estimate escape protein. The escape protein value for Fth, 69.1%, was less than that for BM (82.8%) and CGM (80.4%; P less than .05) but greater than that for SBM (26.6%; P less than .05). Apparent protein digestion by lambs was similar (P greater than .10) for isonitrogenous diets containing urea (U), BM, Fth, CGM and SBM. Amino acid contents of the protein sources before vs after a 12-h ruminal in situ digestion were similar (P greater than .10). In a growth study, a basal diet of 80% ensiled corncobs and 20% alfalfa was fed to 60 individually fed crossbred steers (215 kg BW). Steers were supplemented with U, BM, Fth, 1/2 BM:1/2 Fth, 1/2 BM:1/2 CGM and 1/3 BM:1/3 Fth:1/3 CGM (protein basis). Protein sources were fed at 30, 45 and 60% of the supplemental N with urea supplying the remainder. Protein efficiency was calculated using the slope ratio technique. Protein efficiency was similar (P greater than .10) for BM- and Fth-supplemented calves. Protein efficiencies were similar (P greater than .10) for BM:CGM, BM:Fth and BM:Fth:CGM combinations. These data indicate the Fth is a digestible high escape protein source that is useful in diets for growing ruminants.     

Manipulation of nitrogen digestion by sheep using defaunation and various nitrogen supplementation regimens

Five ruminally, duodenally, and ileally cannulated sheep (average BW 62 kg) were fed 65% roughage: 35% concentrate diets (CP = 15%) in a 5 x 5 Latin square design to study the applicability of using a combination of defaunation with N supplements (soybean meal [SBM], corn gluten meal [CGM], blood meal [BM], urea, and casein) with different extents of ruminal degradation to manipulate microbial protein synthesis and amount of ruminal escape protein. Diets were fed twice daily (1,759 g DM/d). Defaunation was accomplished with 30-ml doses of alkanate 3SL3 (active ingredient: sodium lauryl diethoxy sulfate)/sheep daily for 3 d with 2 d of fasting. Treatment 1 (control) involved feeding faunated sheep a diet in which the supplemental N (45% of total dietary N) was 67% SBM N and 33% urea N. Treatment 2 involved feeding defaunated sheep the same diet as the control. Treatments 3, 4, and 5 involved feeding defaunated sheep diets in which the supplemental N source was either 67% CGM-BM (1:1 N ratio) N:33% urea N, or 33% CGM-BM N:67% urea N or 33% CGM-BM N:33% urea N:33% casein N, respectively. Compared with the faunated control, defaunation decreased (P less than .05) ruminal ammonia concentration (19 vs 26 mg/dl) and increased (P less than .05) CP flow to the duodenum (253 vs 214 g/d) due to a trend for increases in both bacterial (BCP) and nonbacterial (NBCP) CP flows.(ABSTRACT TRUNCATED AT 250 WORDS)     

Efficacy of using a combination of rendered protein products as an undegradable intake protein supplement for lactating, winter-calving, beef cows fed bromegrass hay

Seventy-two (36 in each of two consecutive years) lactating, British-crossbred cows (609 +/- 19 kg) were used to evaluate effects of feeding a feather meal-blood meal combination on performance by beef cows fed grass hay. Bromegrass hay (9.6% CP, DM basis) was offered ad libitum and intake was measured daily in individual Calan electronic headgates. Acclimation to Calan gates began approximately 20 d after parturition, and treatments were initiated 21 d later. Cows were assigned randomly to one of four treatments (DM basis) for 60 d: 1) nonsupplemented control (CON), 2) energy control (ENG; 790 g/d; 100% beet pulp), 3) degradable intake protein (DIP; 870 g/d; 22% beet pulp and 78% sunflower meal), or 4) undegradable intake protein (UIP; 800 g/d; 62.5% sunflower meal, 30% hydrolyzed feather meal, and 7.5% blood meal). Net energy concentrations of supplements were formulated to provide similar NE(m) intakes (1.36 Mcal/d). The DIP and UIP supplements were calculated to supply similar amounts of DIP (168 g/d) and to supply 64 and 224 g/d of UIP, respectively. Forage DMI (kg/d) decreased in supplemented vs. nonsupplemented (P = 0.03) and DIP vs. UIP (P = 0.001); however, when expressed as a percentage of BW, forage DMI was not different (P = 0.23). Supplemented cows tended (P = 0.17) to lose less BW than CON. Body condition change was not affected (P = 0.60) by postpartum supplementation. No differences were noted in milk production (P = 0.29) or in calf gain during the supplementation period (P = 0.74). Circulating insulin concentrations were not affected by treatment (P = 0.42). In addition, supplementation did not affect circulating concentrations of NEFA (P = 0.18) or plasma urea nitrogen (P = 0.38). Results of the current study indicate that supplementation had little effect on BW, BCS, milk production, or calf BW when a moderate-quality forage (9.6% CP) was fed to postpartum, winter-calving cows in optimal body condition (BCS > 5). Supplemental UIP did not enhance cow performance during lactation. Forage UIP and microbial protein supply were adequate to meet the metabolizable protein requirements of lactating beef cows under the conditions of this study.     

Effects of dietary energy level and protein source on nutrient digestion and ruminal nitrogen metabolism in steers.

Four Simmental steers with ruminal, duodenal, and ileal cannulas were used to examine effects of dietary forage: concentrate ratio and supply of ruminally degradable true protein on site of nutrient digestion and net ruminal microbial protein synthesis. Steers (345 kg) were fed ammoniated corn cob (high forage; HF)- or corn cob/ground corn/cornstarch (low forage; LF)-based diets supplemented with soybean meal (SBM) or a combination of corn gluten meal and blood meal (CB). Diets were fed at 2-h intervals with average DM intake equal to 2.2% of BW. Feeding LF vs HF increased (P less than .05) OM digestion (percentage of intake) in the stomach, small intestine, and total tract. Efficiency of microbial CP synthesis (EMCP; g of N/kg of OM truly fermented) decreased (P less than .05) for LF vs HF (24.1 vs 26.8), but microbial N and total N flows to the small intestine were similar (P greater than .05) between energy levels (average 112 and 209 g/d, respectively). Total N flows to the small intestine were 13.1% greater (P less than .05) for CB than for SBM because of increased (P less than .05) passage of nonmicrobial N. Feeding SBM vs CB increased (P less than .05) EMCP (27.3 vs 23.3) and microbial N flow to the small intestine (127.5 vs 112.5 g/d), but these increases were not likely due to increased ruminal concentrations of ammonia N (NH3 N). Decreased (P less than .05) incorporation of NH3 N into bacterial N and slower turnover rates of ruminal NH3 N for SBM vs CB suggest that direct incorporation of preformed diet components into cell mass increased when SBM was fed. Results of this study suggest that the inclusion of ruminally degradable protein in the diet may increase the supply of products from proteolysis and that this can increase EMCP and microbial protein flow to the small intestine.     

Comparison of soybean meal/sorghum grain, alfalfa hay and dehydrated alfalfa pellets as supplemental protein sources for beef cattle consuming dormant tallgrass-prairie forage

Three experiments were conducted to compare soybean meal/sorghum grain (SBM/SG), alfalfa hay or dehydrated alfalfa pellets (DEHY) as supplemental protein sources for beef cattle grazing dormant range forage. In Exp. 1 (35-d digestion study), 16 ruminally cannulated steers were stratified by weight (average BW 259 kg) and assigned randomly within stratification to: 1) control, no supplement; 2) SBM/SG (25% CP) fed at .48% BW; 3) alfalfa hay (17% CP) fed at .70% BW; or 4) DEHY (17.4% CP) fed at .67% BW. Steers receiving protein supplements displayed at least a twofold increase in forage intake (P less than .10). In addition, steers supplemented with DEHY consumed approximately 15% more forage (P less than .10) than SBM/SG- or alfalfa hay-supplemented steers. Digestible DM intake (kg/d), however, was similar between alfalfa hay- and DEHY-supplemented steers and 20% greater (P less than .10) than for SBM/SG-supplemented steers. In Exp. 2, 82 mature, nonlactating Hereford x Angus cows (average BW 489 kg) were assigned randomly to SBM/SG, alfalfa hay or DEHY supplement treatments, which were replicated in three pastures. Cows supplemented with DEHY gained more weight (P less than .05) during the first 84 d of supplementation and displayed the least amount of weight loss at calving (d 127; P less than .05) and just prior to breeding (P less than .10). In contrast, calving interval (361 d) and pregnancy rate (94%) were unaffected (P greater than .10) by dam's previous supplemental treatment. In Exp. 3, one block (pasture) of cows from Exp. 2 was selected at random and grazing behavior was monitored during week-long periods in January and February. A treatment X time interaction (P less than .05) occurred for total time spent grazing; treatments did not differ in January, but cows supplemented with alfalfa hay spent less time grazing in the February grazing period. In conclusion, DEHY and alfalfa hay appear to be at least as effective as SBM/SG as a supplemental protein source for pregnant grazing cows when supplements are fed on an equal CP and ME basis.     

Dried poultry waste for cows grazing low-quality winter forage

Two trials conducted in 1996-97 measured BW and body condition score changes of cows fed different sources of degradable intake protein, including dried poultry waste and soybean meal, while grazing low-quality winter forages. In Trial 1, 60 spring-calving cows (5 yr; 555 kg) were used in an individual supplementation trial. Cows were gathered three times a week, sorted into individual pens, and fed their respective supplement. Cows grazed dormant native Sandhills winter range (common pasture) and were assigned to one of six supplemental treatments: 1) no supplement, 2) urea, 3) 22% dried poultry waste + urea, 4) soybean meal, 5) 22% dried poultry waste + soybean meal, or 6) 44% dried poultry waste. All supplements were based on wheat middlings and soybean hulls and were formulated to contain 44% CP. Thirty-six cows were selected randomly (six per treatment) for a 5-d measurement of forage intake from December 16 through December 20, 1996. Cows receiving supplements gained more weight (P < 0.001) and maintained greater body condition (P < 0.001) than unsupplemented cows. Cows receiving urea gained less (P < 0.10) than cows receiving a source of natural protein, but body condition remained similar. No differences were found in daily forage or total organic matter intake (P > 0.10). In Trial 2, cows grazed corn residues. Forty-eight spring-calving cows were group-fed supplements in one of six 4-ha paddocks. Cows received supplements containing either soybean meal or dried poultry waste that were the same as the soybean meal and 44% dried poultry waste supplements fed in Trial 1; gains were not different (P > 0.10). Under the economic conditions that existed at the time of these experiments, the supplement containing dried poultry waste resulted in a savings of $.04 per cow per day and a total savings of $3.20 per cow over an 80-d period. Feeding a supplement containing dried poultry waste resulted in performance similar to that when feeding a more conventional supplement containing soybean meal.     

Effects of supplemental protein source and metabolizable energy intake on nutritional status in pregnant ewes.

Two experiments were conducted to evaluate effects of supplemental protein source and ME intake (Exp. 1) on ewe nutritional status during pregnancy. Forty-two mature Targhee ewes were allotted randomly in Exp. 1 to one of six treatments (n = 7) using a 2 x 3 factorial arrangement. Ewes were individually fed chopped barley straw and supplements containing either urea (U), soybean meal (SBM), or blood meal (BM) plus SBM during the 84-d experiment. Straw and supplement intakes were adjusted to meet either 80 or 100% of ME requirements. In Exp. 2, 30 pregnant Targhee ewes that were allotted randomly to one of three groups (n = 10) were individually fed protein supplements similar to those in Exp. 1 and had group access to long-stem barley straw. In Exp. 1, ewes fed BM + SBM gained more (P less than .05) weight, lost less (P less than .05) body condition, and had increased (P less than .05) wool fiber length compared with ewes fed U; SBM ewes were intermediate (P less than .05) in response. Ewes fed BW + SBM had increased (P less than .05) blood urea N and albumin concentrations compared with ewes fed U. Metabolizable energy intake did not affect (P greater than .05) ewe performance or serum metabolite concentrations. Ewes fed BM + SBM in Exp. 2 gained more (P less than .05) weight than ewes fed either SBM or U, and ewes fed SBM lost less weight (P less than .05) than ewes fed U.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of corn gluten feed on forage intake, digestibility and ruminal parameters of cattle fed native grass hay

Thirty-two beef cows (467 kg) were individually fed native grass hay and supplement for two 14-d periods in each of 2 yr. Supplement treatments and amounts fed (kilograms/day) were negative control (NC), 0, or equal amounts of protein from soybean meal (SBM), .7; a blend of soybean meal and corn gluten feed (SBM/CGF), 1.0; or corn gluten feed (CGF) 1.6. Cows received supplement at 0645 and had ad libitum access to native grass hay from 0700 to 1130 and from 1530 to 2000. Compared with NC, all protein supplements increased (P less than .05) ruminal NH3, propionate and butyrate concentrations at 4 and 25 h postfeeding. Ruminal fluid pH, total VFA and acetate concentrations at 4 and 35 h postfeeding were not affected by supplements. All supplements increased (P less than .01) hay intake as well as hay, acid detergent fiber (ADF) and total diet dry matter (DM) digestibility. Compared to supplemental SBM, feeding CGF reduced (P less than .01) hay intake. Calculated daily intakes of metabolizable energy (ME) were 12, 17, 18, and 17 Mcal for NC, SBM, SBM/CGF and CGF, respectively. Hay intake, DM and ADF digestibility and ME intakes tended to be higher for SBM/CGF than for the average of SBM and CGF fed alone. Intakes of digestible DM and ADF were not altered by protein supplements, suggesting that intake responses were due to increased diet digestibility. Corn gluten feed appears to be an effective source of supplemental protein and energy for cows consuming low-quality roughage.     

Effect of energy source and ruminally degradable protein addition on performance of lactating beef cows and digestion characteristics of steers

Two trials were conducted to determine the effect of energy source (ENG) and ruminally degradable protein (RDP) on lactating cow performance and intake and digestion in beef steers. In Trial 1, 78 cow-calf pairs were used in a 2 x 2 factorial design to determine the effect of ENG (corn or soyhulls; SH) and RDP (with our without sunflower meal) to a forage diet for lactating beef cows. The basal diet consisted of 75% grass hay (11.5% CP) and 25% wheat straw (7.4% CP). Supplement treatments and predicted RDP balances were corn (-415 g of RDP/d); SH (-260 g of RDP/d); corn plus RDP (0 g of RDP/d); or SH plus RDP (0 g of RDP/d). Data were analyzed as a split-plot in time, with pen as the experimental unit (two pens per treatment). No interaction between ENG and RDP was present (P > 0.08) for any response variable. No differences (P > 0.39) due to ENG or RDP were noted for BW, BCS, or milk yield; however, final calf weight tended to increase with ENG (P = 0.06). In Trial 2, a 5 x 5 Latin square was used to determine effects of ENG and RDP on intake and digestion in steers (686 +/- 51 kg BW). Treatments were arranged as a 2 x 2 plus one factorial and comprised a control (CON; grass hay, 7% CP), grass hay plus 0.4% BW SH, grass hay plus 0.4% BW SH and 0.15% BW sunflower meal, grass hay plus 0.4% BW corn, and grass hay plus 0.4% BW corn and 0.2% BW sunflower meal. Preplanned contrasts included main effects of ENG and RDP, ENG x RDP interaction, and CON vs. supplemented (SUP) treatments. Supplementation increased total DMI compared with CON (P = 0.001), but forage DMI was greater (P = 0.001) for CON than for SUP. An ENG x RDP interaction occurred for forage DMI (P = 0.02); addition of RDP to corn decreased forage intake, whereas addition of RDP to SH had no effect. There was an ENG x RDP interaction (P = 0.001) for ruminal pH; pH tended to increase with RDP addition to SH (P = 0.07), but decreased with RDP addition to corn (P = 0.001). Supplementation increased ruminal ammonia compared with CON (P = 0.001). Likewise, RDP increased ruminal ammonia (P = 0.001). An interaction occurred for OM disappearance (OMD; P = 0.01). The RDP addition to SH numerically decreased OMD (P = 0.23), whereas RDP addition to corn numerically increased OMD (P = 0.14). Intake and digestion seem to respond differently to RDP addition depending on supplemental energy source. Both corn or SH seem to be suitable supplements for the quality of forage used in this trial. Addition of supplemental protein did not improve cow or calf performance.     

Effects of cottonseed meal supplementation time on ruminal fermentation and forage intake by Holstein steers fed fescue hay.

Four ruminally cannulated Holstein steers (average BW 303 kg) were used in a 4 x 4 Latin square design digestion trial to study the influence of daily cottonseed meal (CSM; 1.6 g of CP/kg of BW) supplementation time on forage intake and ruminal fluid kinetics and fermentation. Steers were housed individually in tie stalls and were fed chopped fescue hay on an ad libitum basis at 0600 and 1400. Treatments were 1) control, grass hay only (CON) and grass hay and CSM fed once daily at 2) 0600 (EAM) 3) 1000 (MAM), or 4) 1400 (PM). Ruminal NH3 N concentrations reflected a time of supplementation x sampling time interaction (P less than .05); CON steers had the lowest (P less than .05) ruminal NH3 N concentrations at all times other than at 0600, 1000, 1200, and 2400, when they did not differ (P greater than .05) from at least one of the supplemented groups. Forage intake, ratio of bacterial purine:N, rate of DM and NDF disappearance, and ruminal fluid kinetics were not influenced (P greater than .05) by supplementation time. Total ruminal VFA differed (P less than .05) between CON and supplemented steers, as well as among supplemented steers (linear and quadratic effects P less than .05). Acetate, propionate, and valerate proportions were influenced (P less than .05) by a sampling time X supplementation time interaction. Under the conditions of this study, greater peak ammonia concentrations with morning supplementation than with afternoon supplementation did not stimulate ruminal fermentation or rate of NDF disappearance.     

Intestinal supply of amino acids in sheep fed alkaline hydrogen peroxide-treated wheat straw-based diets supplemented with soybean meal or combinations of corn gluten meal and blood meal

The intestinal supply of amino acids (AA) in sheep fed alkaline hydrogen peroxide-treated wheat straw (AHPWS)-based diets supplemented with soybean meal (SBM) or corn grain plus combinations of corn gluten meal (CGM) and blood meal (BM) was measured in a 5 X 5 latin square. Sheep (avg wt 45 kg) with ruminal, duodenal and ileal cannulas were fed diets containing 65% AHPWS supplemented with the following protein sources: soybean meal (SBM), corn gluten meal (CGM), blood meal (BM), 2/3 CGM:1/3 BM and 1/3 CGM:2/3 BM. Total nitrogen (N) flow at the duodenum was not affected (P greater than .05) by protein source. Flows of bacterial N and AA increased (P less than .05) and flows of nonbacterial N and AA decreased (P less than .05) when wethers were fed SBM vs corn plus other protein sources. When diets contained SBM, quantities of total AA at the duodenum were lower (P less than .05) and the profile of AA supplied to the intestine was altered substantially. Total flows of AA at the duodenum and total quantities of AA disappearing from the small intestine were similar (P greater than .05) for all diets containing BM and CGM, but flows and disappearance of valine, histidine, lysine and arginine increased linearly (P less than .05), whereas flows and disappearance of leucine, isoleucine and methionine decreased linearly (P less than .05) as BM replaced CGM in the diets. Results suggest that quantities of individual AA flowing to the duodenum and disappearing from the intestine of wethers fed AHPWS-based diets can be altered by source of dietary protein. Furthermore, feeding protein sources resistant to ruminal degradation in combination may improve the profile of AA supplied to the intestine.