Evaluation of dairy food processing wash water solids as a protein source: II. Microbial protein synthesis, duodenal nitrogen flow, and small intestinal amino acid disappearance

Twelve ruminally, duodenally, and ileally-cannulated Hereford heifers (average initial BW 313 +/- 20 kg) were used in a replicated experiment to evaluate dairy food processing wash water solids (WWS) as a protein source. Heifers were fed 2.8 kg of chopped (7.6 cm) hay and one of three supplements (1.5 kg/d, DM basis). Supplements were formulated to be similar in energy and contained 1.0 (control), 23.2 (WWS), and 21.6% (soybean meal; SBM) CP on an OM basis. Total N and nonammonia N entering the duodenum (g/d) were greater (P less than .10) for heifers fed WWS and SBM supplements than for controls. Bacterial N flow (g/d) at the duodenum was less (P less than .10) for controls (43.9) than for WWS- (63.9) and SBM- (69.9) supplemented heifers. Feed escape N (g/d) was greater (P less than .10) for WWS-fed heifers than for those fed SBM (32.1 vs 20.7 g/d, respectively). Total tract N digestion (g/d) was greatest (P less than .10) for SBM, intermediate for WWS, and least for control heifers. Microbial protein synthesis (g/kg of OM intake) was enhanced (P less than .10) by WWS and SBM supplementation, but efficiency of synthesis (g/kg of OM fermented) did not differ among treatments. Essential amino acid (AA) disappearance in the small intestine (g/d) was less (P less than .10) for control than for the other two treatments. Nonessential AA disappearance was greatest (P less than .10) for the WWS and least (P less than .10) for the control treatment.(ABSTRACT TRUNCATED AT 250 WORDS)     

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.     

Effects of supplemental protein percentage and feeding level on intake, ruminal fermentation, and digesta passage in beef steers fed prairie hay.

Twelve ruminally cannulated steers (average initial BW 357 kg) were allotted to four treatments (three steers per treatment) in a replicated 4 x 4 Latin square design with 21-d periods (12 d for adaptation and 9 d for collection) to compare the effects of protein supplements that differed in percentage of CP and feeding level on low-quality forage utilization. Treatments were 1) control (C), ad libitum access to 5.6% CP prairie hay, 2) C +600 g of DM.steer-1.d-1 of a 43% CP supplement based on cottonseed meal (PS), 3) C + 1,200 g of DM.steer-1.d-1 of a 22% CP supplement based on corn grain and cottonseed meal (GS), and 4) C + 600 g of DM.steer-1.d-1 of a 22% CP supplement based on corn grain and cottonseed meal (LS). Ruminal total VFA concentrations were increased 8% (P less than .07) by PS vs GS 1 h after supplementation. Among supplemented steers, ruminal acetate (mol/100 mol) was decreased 1.2 mol/100 (P less than .03) by GS vs PS and LS; however, supplementation did not affect (P greater than .10) acetate proportions compared with C. Neither propionate nor butyrate was affected (P greater than .10) by supplementation, but among supplemented steers, butyrate proportions were 8% greater (P less than .03) for GS than for PS and 5% less (P less than .10) for LS than for the average of GS and PS. Ruminal pH did not differ (P greater than .10) among treatments. Ruminal ammonia concentrations were increased 1.4 to 4.8 mg/100 mL (P less than .07) by supplementation and typically were less for LS than for PS and GS at most sampling times. Prairie hay DMI (average = 16.3 g/kg BW) was not affected (P greater than .10) by supplementation. Fluid dilution rate was 8% faster (P less than .01) when steers were supplemented than when they were not fed supplement, and fluid dilution rate was increased 4% (P less than .04) by GS compared with PS. Particulate digesta passage rate was not affected (P greater than .10) by treatment, but total tract retention time was decreased (P less than .01) 10% by supplementation. Extent and rate of prairie hay NDF digestion in situ were not greatly affected by supplementation, but in situ disappearance of supplement N was 6 to 10 percentage units less (P less than .06) for GS than for PS and 2 to 6 percentage units less for LS than for the average of PS and GS supplements.(ABSTRACT TRUNCATED AT 400 WORDS)     

Effects of lactational status on forage intake, digestibility, and particulate passage rate of beef cows supplemented with soybean meal, wheat middlings, and corn and soybean meal

Sixteen mature, lactating (453 kg) and 16 nonlactating (487 kg) Hereford and Angus x Hereford cows were used to determine effects of different dietary supplements and lactational status on forage intake, digestibility, and particulate passage rate. Supplement treatments and amounts fed (kg/d) were as follows: control, 0; and equal daily amounts of CP from soybean meal (SBM), 1.36; wheat middlings (WM), 3.41; or a blend of corn and soybean meal (corn-SBM; 22% corn and 76% SBM), 3.41. Cows were fed supplements at 0800 and had ad libitum access to prairie hay (4.9% CP) in stalls from 0800 to 1100 and from 1300 to 1600 for three 17-d periods. Lactational status and supplement type did not interact (P greater than .50) for hay DMI, DM digestibility, or particulate passage rate. Cows fed SBM ate more hay DM (P less than .01) and had greater hay DM digestibility (P less than .01) than did cows in other treatment groups. Average hay DMI (kg/100 kg of BW) was 1.95, 2.16, 1.94, and 1.89, and hay DM digestibility was 52, 61, 55, and 53% for control, SBM, WM, and corn-SBM supplements, respectively. Total diet DM digestibility was increased by supplementation (P less than .01), but no differences (P greater than .18) were observed among supplements. Lactating cows ate more (P = .13) hay DM (2.11 vs 1.87 kg/100 kg of BW) and had greater (P less than .05) fecal output (4.6 vs 4.3 kg/d) than did nonlactating cows. Dry matter digestibility and particulate passage rate were not affected (P greater than .35) by lactational status.(ABSTRACT TRUNCATED AT 250 WORDS)     

Low- and high-quality forage utilization by heifers and mature beef cows.

Eight cows (7 to 9 yr old, 522 kg) and six heifers (10 mo old, 169 kg) were fed either alfalfa hay (18.7% CP) or mature brome hay (5.1% CP) to determine the effect of cattle age on apparent forage utilization. Cattle were fitted with ruminal and duodenal cannulas and were individually fed once daily (ad libitum intake, 1000). The split-plot design consisted of age (whole-plot) and two sampling periods feeding alfalfa or brome hay (subplot). Each period consisted of 28 d: d 1 to 13 for adaptation, d 13 to 20 for feed intake determination, and d 20 to 28 for sampling. Nylon bags containing NDF substrate from alfalfa or brome hay were incubated ruminally for 0, 3, 6, 12, 24, 48, 96, and 192 h to determine the rate and extent of fiber degradation. Ruminal liquid dilution rate and fermentation characteristics were conducted on d 27. Ruminal fill was determined by total evacuation at 0800 on d 28. Cows consumed more feed (BW.75; P<.01) and had greater ruminal OM fill (P = .04) but had similar fluid fill (P = .88) compared with heifers. Ruminal liquid dilution rate was greater in cows than in heifers (P<.01). The rate of in situ NDF degradation was 3 and .5% per hour greater in cows than in heifers when alfalfa and brome hay were fed, respectively (age x hay, P<.01). Ruminal NDF digestibility as a percentage of intake was greater in cows than in heifers (P<.01). Numbers of ruminal cellulolytic bacteria were not affected by treatment (P>.21). These data indicate that mature cows have a smaller ruminal fluid fill that turns over more rapidly, and this may be responsible for a faster rate of ruminal fiber degradation in cows than in young heifers.     

Influence of ruminal or duodenal soybean oil infusion on intake, ruminal fermentation, site and extent of digestion, and microbial protein synthesis in beef heifers consuming grass hay.

Six heifers (two Hereford X Jersey, four Hereford X Longhorn; average BW 278 kg) cannulated at the rumen and duodenum and fed a grass hay (fescue/orchardgrass) diet were used in a replicated 3 X 3 Latin square. Treatments were either no infusion (C), 150 ml of duodenally infused soybean oil (DI), or 150 ml of ruminally infused soybean oil (RI)/heifer twice daily for a total daily infusion of 300 ml of soybean oil. Periods of the Latin square included 18 d for adaptation and 5 d for collection. Forage OM, ADF, NDF, and N intakes were not affected (P greater than .10) by soybean oil infusion. Ruminal (P = .11) and total tract (P less than .10) OM digestibilities were decreased by RI compared with C or DI, but ADF and NDF digestibilities were not affected by treatment. Duodenal N (P less than .05) and microbial N flows were increased (P less than .10) for C and RI compared with DI. Microbial efficiency (g of N/kg of OM truly fermented) was improved (P less than .10) by RI compared with DI but did not differ (P greater than .10) from C. Ruminal pH was lower (P less than .05) with RI than with either C or DI. Ruminal NH3 N, total VFA, and acetate were not affected (P greater than .10) by treatment. Propionate (mol/100 mol) was greater (P less than .05) with RI than with DI and C, but the proportion of butyrate did not differ among treatments. These data indicate minimal direct benefits for improving forage usage as a result of soybean oil infusion with a 100% grass diet; however, animals should realize benefits from additional dietary energy provided by infused lipid.     

Effects of energy supplementation frequency and forage quality on performance, reproductive, and physiological responses of replacement beef heifers

The objective of this study was to compare performance, physiological, and reproductive responses of beef heifers consuming forages differing in nutritional quality and offered a low-starch energy supplement at 2 different frequencies. Forty-eight Brahman × British heifers (initial age = 294 ± 3 d) were allocated into 1 of 16 drylot pens (3 heifers/pen) which were randomly assigned to receive, in a 2 × 2 factorial arrangement of treatments: 1) low-quality hay [LQ; stargrass (Cynodon nlemfuensis) with 8% CP and 81% NDF, DM basis] and daily supplementation (S7); 2) LQ and supplementation 3 times weekly (S3); 3) medium-quality hay [MQ; bermudagrass (C. dactylon) with 12% CP and 74% NDF, DM basis] and S7; and 4) MQ and S3. Throughout the study (d 0 to 120), hay was offered in amounts to ensure ad libitum access, and a supplement based on soybean hulls and wheat middlings was offered at weekly rates of 15.8 and 7.9 kg/heifer (DM basis) for LQ and MQ, respectively. Forage and total DMI were evaluated daily, from d 20 to 26, d 34 to 40, and d 48 to 54. Blood samples were collected weekly for determination of plasma progesterone to evaluate puberty attainment. Blood samples were also collected daily, from d 13 to 16, d 27 to 30, d 41 to 44, and d 55 to 58 for determination of plasma urea nitrogen (PUN), glucose, insulin, IGF-I, and NEFA. On d 60, heifers were reallocated by treatment into 4 paddocks and exposed to Angus bulls (1:12 bull:heifer ratio) until d 120. Date of conception was estimated retrospectively by subtracting gestation length (286 d) from the calving date. Heifers receiving S7 had similar (P = 0.52) ADG compared with S3 heifers (0.27 vs. 0.25 kg/d). Heifers provided S7 had less daily variation in hay DMI and plasma concentrations of glucose, NEFA, and IGF-I compared with S3 cohorts (supplementation frequency × day interaction; P < 0.01). Similarly, heifers offered MQ and LQ and receiving S7 had less daily variation in total DMI, energy and protein intake, and plasma concentrations of PUN compared with heifers offered MQ and LQ and receiving S3 (hay quality × supplementation frequency × day interaction; P < 0.01). Attainment of puberty and pregnancy were hastened in S7 heifers compared with S3 heifers (supplementation frequency × week interaction; P < 0.02). Therefore, reproductive development of beef replacement heifers consuming diets based on low- and medium-quality forages are enhanced when low-starch energy supplements are offered daily instead of 3 times weekly.     

Pregnancy and lactation in beef heifers grazing tallgrass prairie in the winter: influence on intake, forage utilization, and grazing behavior.

Six ruminally and eight bifistulated (ruminal and esophageal) Hereford x Angus heifers were used to determine effects of pregnancy and early lactation on forage intake and utilization under grazing conditions. Three ruminally and three bifistulated heifers were bred (pregnant/lactating; P/L; average calving date was February 11, 1989); remaining heifers served as controls (C). The experiment consisted of three periods (P1 = average of 55 d before parturition; P2 = average of 12 d before parturition; P3 = average of 26 d after parturition). All heifers grazed the same 24-ha Flint Hills range pasture. Dehydrated alfalfa pellets were supplemented at .5% BW/heifer daily prepartum and at .8% BW/heifer daily postpartum. Treatment x period interactions were noted (P less than .10) for forage OM intake, ruminal capacity, indigestible ADF (IADF) fill, and grazing time but not for OM digestibility or IADF passage rate (P greater than .10). In P1 and P3, P/L heifers had greater (P less than .10) forage OM intake than C heifers, whereas no differences were noted (P greater than .10) in P2. Pregnant/lactating heifers spent less time (P less than .10) grazing than did controls in P2 and more time (P less than .10) than controls in P3. Ruminal IADF fill and ruminal capacity, as measured by water fill, tended (P = .14 and .16, respectively) to differ between the two groups in P2. Digestibility of OM was unaffected (P greater than .10) by physiological status, whereas IADF passage rate was greater (P less than .10) in P/L heifers. Only minor differences were noted for the chemical composition of diets selected by the two groups. Ruminal fermentation patterns shifted only slightly; the largest effects were in P3, when P/L heifers had greater (P less than .10) propionate and less (P less than .10) acetate (mol/100 mol) than C heifers. In summary, during the period just before parturition, differences in forage OM intake between P/L and C heifers disappeared, and ruminal fill and capacity tended to be lower for P/L heifers. Intake was 16% greater for P/L than for C heifers during the early postpartum period. Organic matter digestibility was not influenced by physiological status, even though IADF passage rates were greater for P/L heifers.     

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)     

Effects of increasing level of supplemental barley on forage intake, digestibility, and ruminal fermentation in steers fed medium-quality grass hay

Objectives of this research were to evaluate effects of increasing level of barley supplementation on forage intake, digestibility, and ruminal fermentation in beef steers fed medium-quality forage. Four crossbred ruminally cannulated steers (average initial BW = 200 +/- 10 kg) were used in a 4 x 4 Latin square design. Chopped (5 cm) grass hay (10% CP) was offered ad libitum with one of four supplements. Supplements included 0, 0.8, 1.6, or 2.4 kg of barley (DM basis) and were fed in two equal portions at 0700 and 1600. Supplements were fed at levels to provide for equal intake of supplemental protein with the addition of soybean meal. Forage intake (kg and g/kg BW) decreased linearly (P < 0.01), and total intake increased linearly (P < 0.03) with increasing level of barley supplementation. Digestible OM intake (g/kg BW) increased linearly (P < 0.01) with increasing level of barley supplementation; however, the majority of this response was observed with 0.8 kg of barley supplementation. Treatments had only minor effects on ruminal pH, with decreases occurring at 15 h after feeding in steers receiving 2.4 kg of barley supplementation. Total-tract digestibility of DM, OM, NDF, and CP were increased (P < 0.04) with barley supplementation; however, ADF digestibility was decreased by 1.6 and 2.4 kg of barley supplementation compared with controls. Ruminal ammonia concentrations decreased linearly (P < 0.01) at 1 through 15 h after feeding. Total ruminal VFA concentrations were not altered by dietary treatments. Ruminal proportions of acetate and butyrate decreased (P < 0.10) in response to supplementation. Rate, lag, and extent (72 h) of in situ forage degradability were unaffected by treatment. Generally, these data are interpreted to indicate that increasing levels of barley supplementation decrease forage intake, increase DM, OM, and NDF digestibility, and indicate alteration of the ruminal environment and fermentation patterns.     

Influence of supplemental alfalfa quality on the intake, use, and subsequent performance of beef cattle consuming low-quality roughages.

Three experiments were conducted to evaluate influences of supplemental alfalfa quality on intake and use of low-quality meadow grass roughages (MG) by beef cattle. In Exp. 1, 15 steers (250 kg) were assigned to three treatments: 1) MG (5.2% CP), no supplement; 2) MG plus high-quality alfalfa (18.8% CP); and 3) MG plus low-quality alfalfa (15.2% CP). High- and low-quality alfalfa supplements were fed at .45 and .55% BW, respectively. Total DMI was greater (P < .01) for alfalfa-supplemented steers than for MG. Likewise, intake of digestible DM, DM digestibility (DMD), and ruminal ammonia level were greater (P < .01) for supplemented steers. In Exp. 2, 96 pregnant Hereford x Simmental cows (537 kg; body condition [BC] score 4.86) were assigned to the same treatments as in Exp. 1. For d 0 to 42, cows grazed on 19.1 ha of stockpiled MG (4,539 kg/ha; 6.8% CP), whereas, on d 43 to 84, cows received MG hay (5.2% CP). Supplemented cows gained more BW (P < .01), BC score (P < .01), and had heavier calf birth weight (P < .01) than nonsupplemented cows. However, there were no treatment effects (P > .10) on cow cyclicity, pregnancy rate, or calving interval. In Exp. 3, 90 pregnant Angus x Hereford cows (475 kg; BC score 4.59) were assigned to three treatments: 16.1%, 17.8% or 20.0% CP alfalfa supplement, with levels of .63, .55, and .50% of BW, respectively. Weight gain and BC score for the 84-d study displayed a quadratic response (P < .10), yet represented only 7 kg BW and .2 units of BC score. In conclusion, alfalfa hay supplementation was effective in increasing DMI and digestibility. However, alfalfa hay quality did not dramatically affect BW, BC score, and(or) calf birth weight, when fed on an isonitrogenous basis.     

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.     

Supplementation to meet metabolizable protein requirements of primiparous beef heifers: I. Performance,forage intake,and nutrient balance

Three experiments were conducted to evaluate the response of supplementing primiparous heifers based on the metabolizable protein (MP) system during pregnancy and lactation. In Exp. 1, 12 pregnant, March-calving heifers (432 +/- 10 kg) grazing Sandhills range were randomly allotted to one of two treatments: supplementation based on either the MP system (MPR) or the CP system (CPR). Supplements were fed to individual heifers from October to February and no hay was offered. Grazed forage organic matter intake (FOMI) was measured in November, January, and February. In Exp. 2, 18 heifers (424 +/- 8 kg) were randomly allotted to one of three treatments: 1) supplementation based on the MP system with hay fed in January and February (average 2.0 kg/d; MPR/hay), 2) supplementation based on the CP system, with hay fed in January and February (CPR/hay), or 3) supplementation based on the MP system, with no hay fed (MPR/no hay). Supplements were fed from October to February, and FOMI was measured in December and February. In Exp. 3, lactating 2-yr-old cows (394 +/- 7 kg) maintained on meadow hay were supplemented to meet either 1) MP requirements (LMPR) or 2) degradable intake protein requirements (LDIPR). Body weight (BW) and body condition score change, hay intake, and milk production were measured. In Exp. 1, grazed FOMI decreased (P = 0.0001) from 1.9% of BW in November to 1.2% in February, but no differences among treatments were detected for FOMI or BW change. In Exp. 2, grazed FOMI declined (P = 0.0001) from 1.7% of BW in December to 1.1% in February, with no differences among treatments. Heifers on the MPR/hay and CPR/hay treatments had higher (P = 0.0018) total intake (grazed forage + hay intake) in February (1.7% BW) than the MPR/no hay heifers (1.1% BW). Heifers on the MPR/no hay treatment had a lower weight (P = 0.02) and tended (P = 0.11) to have a lower BCS than heifers on other treatments. In Exp. 3, the LMPR cows had higher (P = 0.02) ADG than LDIPR cows (0.41 and 0.14, respectively), but treatment did not affect milk production. Organic matter hay intake averaged 2.4% of BW. We conclude that supplementation to meet MP requirements had little benefit to heifer performance during gestation, but increased weight change during lactation. Because grazed forage intake decreased from 1.9 to 1.1% of BW with advancing gestation, supplemental energy is necessary to reduce weight and condition loss of gestating hefiers grazing dormant Sandhills range.     

Early aspects of locoweed toxicosis and evaluation of a mineral supplement or clinoptilolite as dietary treatments.

Sixteen crossbred beef heifers were used to determine the efficacy of serum clinical profiles as diagnostic tools for detection of early stages of locoweed toxicity and to test the ability of two mineral supplements for prevention or therapy of toxicosis. Dietary treatments were (DM basis) 1) 100% sorghum sudangrass hay, 2) 80% sorghum sudangrass hay:20% locoweed, 3) 80% sorghum sudangrass hay:20% locoweed plus 100 g of Silent Herder Mineral Mix (a mineral supplement reported to alleviate locoweed toxicity), and 4) 80% sorghum sudangrass hay:20% locoweed plus 100 g of clinoptilolite (a natural zeolite clay). Diets were fed at 1.5% of BW for 28 d, after which heifers had ad libitum access to sorghum sudangrass hay for 14 d. Jugular blood was sampled before feeding every 7 d, and at 2, 4, 6, and 8 h after feeding on d 28. Compared with controls, heifers fed locoweed had elevated (P less than .01) serum alkaline phosphatase activities from d 7 through 35. On d 42, alkaline phosphatase activities in heifers previously fed locoweed were lower (P less than .05) than in control heifers. Serum glutamic oxaloacetic transaminase activities were elevated (P less than .01) in heifers fed locoweed from d 7 through 42 compared with control heifers. In heifers fed locoweed, serum Fe concentrations were less (P less than .01) on d 7 through 28, but no treatment effects were noted (P greater than .10) on d 35 or 42.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of soybean lipid on growth and ruminal nitrogen metabolism in cattle fed soybean meal or ground whole soybeans

Three experiments were conducted to determine the effect of soybean lipid on ruminal proteolysis of soybean meal (SBM) and ground whole soybeans (GSB). Experiment 1 was a 92-d growth experiment using 120 calves (206 kg) allotted to 12 pens of 10 calves each. Three replicate pens were assigned to each of the treatment supplements: low SBM (LSBM), low GSB (LGSB), high SBM (HSBM) and high GSB (HGSB). Calves received ad libitum amounts of corn silage top-dressed with the respective supplement (.81 kg/head). High protein supplements produced greater (P less than .05) gains than low protein supplements, with HSBM calves gaining faster (P less than .05) than HGSB calves and LSBM and LGSB calves having similar (P greater than .10) gains. In Exp. 2, 15 ruminally cannulated Angus X Hereford heifers (380 kg) fed corn silage were used to determine ammonia-N release from the treatment supplements: ground corn (control), GSB, SBM and SBM coated with soybean oil (SBMO). Heifers fed the control supplement had lower (P less than .05) ruminal NH3-N concentrations than those consuming soybean protein. Ruminal NH3-N concentrations were similar (P greater than .10) for GSB and SBM; whereas, SBMO had lower (P less than .10) concentrations than SBM through 3 h. In Exp. 3, two ruminally cannulated Angus X Jersey steers (250 kg) were used to determine in situ disappearance of SBM, GSB and SBMO. Total and feed N disappearances were greater (P less than .001) for GSB than SBM or SBMO.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of protein supplementation on site and extent of digestion, forage intake, and nutrient flow characteristics in steers consuming dormant bluestem-range forage

Four multicannulated Holstein steers (initial BW 424 +/- 16 kg) were used in a 4 x 4 Latin square to determine the influence of protein supplementation on forage intake, site and extent of digestion, and nutrient flow in steers consuming dormant bluestem-range forage (2.3% CP). Treatments were 1) control, no supplement; 2) 1.8 kg of low-protein supplement, 12.8% CP (Low-CP); 3) 1.8 kg of moderate-protein supplement, 27.1% CP (Mod-CP); and 4) 2.7 kg of dehydrated alfalfa pellets, 17.5% CP (Dehy). The Dehy supplement was fed to provide the same amount of CP/d as Mod-CP, and all supplements provided similar amounts of ME/d. Forage DMI was increased (P less than .05) by feeding Mod-CP and Dehy. Ruminal OM digestibility was 39% greater (P less than .05) for the Mod-CP and Dehy supplementations than for the Low-CP supplementation and control. Ruminal CP digestibility was negative for all treatments, and control (-326%) was less (P less than .05) than supplemented treatments (average -27%). Total tract OM digestibility was greatest (P less than .10) for steers fed Mod-CP and least for control steers; Low-CP and Dehy steers were intermediate. Total tract NDF digestibility tended (P = .15) to be less with Low-CP than with Mod-CP and Dehy. Duodenal N flow was greater (P less than .05) with Mod-CP and Dehy than with Low-CP and control. In summary, supplementation with Mod-CP increased forage intake, digestion, and duodenal N flow compared with Low-CP or control; however, the response was similar when Mod-CP and Dehy supplements were fed to provide equivalent amounts of CP and ME daily.     

Effect of distillers grains or corn supplementation frequency on forage intake and digestibility

Ten ruminally cannulated heifers (BW = 416 kg; SD = 24) were used to test the effect of the form and frequency of supplemental energy on forage DMI and digestibility. Five treatments were arranged in a replicated, 5 x 4 Latin rectangle (n = 8), and included no supplement (control), dry-rolled corn (DRC) fed daily, DRC fed on alternate days (DRC-A), dried distillers grains plus solubles (DDGS) fed daily, and DDGS fed on alternate days (DDGS-A). Supplements fed daily were fed at 0.40% of BW, whereas alternate day-fed supplements were fed at 0.80% of BW every other day. Chopped grass hay (8.2% CP) was fed to allow ad libitum DMI, and the intake pattern was measured. Control heifers had greater (P < 0.01) hay DMI than supplemented heifers (1.88 vs. 1.66% of BW daily, respectively), although total DMI was lower (P < 0.01) for control. Hay DMI did not differ (P = 0.45) between DRC and DDGS, and tended to be lower (P = 0.08) by heifers on DDGS-A and DRC-A than by heifers supplemented daily. Hay intake was lower (P < 0.01) on supplementation days for DDGS-A and DRC-A than on nonsupplemented days. Heifers in alternate-day treatments had fewer (P < 0.01) and larger (P < 0.01) meals and spent less (P < 0.01) time eating than those supplemented daily. Average rumen pH was greater (P = 0.05) for control than supplemented heifers (6.30 vs. 6.19). Control heifers had greater (P = 0.04) rates and extents of NDF disappearance than supplemented heifers. Rate of hay NDF disappearance was lower (P = 0.02) for DRC than for DDGS. Supplementation decreased hay DMI and changed digestion kinetics. Supplementation frequency affected amount and pattern of DMI. Rate of hay NDF disappearance was greater for DDGS than DRC.     

Digestion, feed intake, and live weight gain by cattle consuming bermudagrass hay supplemented with whey.

Three experiments were conducted with cattle consuming bermudagrass hay to determine whether low-level supplements of whey alone, corn alone, or whey plus corn affect feed intake, digestion, and(or) BW gain. Six ruminally and duodenally cannulated beef cows (574 kg), used in a Latin-square trial (Exp. 1), were fed bermudagrass hay without supplementation (control) or with 2.8% whey (low whey, LW), 5.6% whey (high whey, HW), 17.4% ground corn (C), 2.8% whey plus 14.9% corn (C-LW), or 5.6% whey plus 12.4% corn (C-HW). Supplementing with whey and(or) corn increased ruminal butyrate (8.8, 9.4, 10.0, 9.6, 10.5, and 11.0 mol/100 mol of total VFA for control, LW, HW, C, C-LW, and C-HW, respectively; SE = .20). Supplements did not affect microbial N flow at the duodenum. Six Holstein steer calves (158 kg) in a Latin square (Exp. 2) consumed bermudagrass hay ad libitum alone (control) or with .075 or .15% BW whey (LW and HW, respectively), .5% BW ground corn (C), or corn-whey mixes made by substituting whey for corn (C-LW and C-HW). Substituting .15% BW of whey for corn increased (P less than .05) total OM intake slightly (3.99, 3.84, 3.75, 4.11, 4.28, and 4.47 kg for control, LW, HW, C, C-LW, and C-HW, respectively; SE = .10). In an 84-d randomized block experiment (Exp. 3), 96 beef calves (194 kg) consumed (ad libitum) low-quality bermudagrass hay alone or with C, LW, HW, C-LW, or C-HW supplements.(ABSTRACT TRUNCATED AT 250 WORDS)     

Feed intake and digestion by beef cows fed prairie hay with different levels of soybean meal and receiving post-ruminal administration of antibiotics

Six cannulated beef cows (one Angus, two Hereford and three Angus x Hereford; 405 kg) were used in a 6 x 6 latin square experiment with a 2 x 3 factorial arrangement of treatments. Prairie hay (.77% N, 73% neutral detergent fiber [NDF] and 7% acid detergent lignin) was fed ad libitum from d 1 through 14 and at 90% of ad libitum intake from d 15 through 21 during digesta collection. Periods lasted 21 d. Soybean meal (SBM) was offered at 0 (control, C), .12 (low, L) or .24% of body weight (high, H; dry matter basis). Cows received daily doses of an antibiotic mixture (1 g neomycin and .125 g bacitracin) or saline in the duodenum. Prairie hay dry matter (DM) intake increased (P less than .05) linearly with SBM supplementation, being 25 and 40% greater for L and H than for C, respectively. Ruminal fluid concentrations of NH3-N and total volatile fatty acids increased (P less than .05) linearly as SBM was added to the diet. Ruminal fluid dilution rate increased linearly and particulate passage rate increased (P less than .05) quadratically with increasing SBM. True ruminal digestibilities of organic matter, NDF and N increased (P less than .10) quadratically with increasing SBM (organic matter; 50.3, 57.9 and 58.3%; NDF: 54.7, 60.4 and 59.8%; N: 17.5, 45.1 and 51.4% for C, L and H, respectively). Main effects of antibiotic administration were not significant. Increases in DM intake when SBM was given were large compared with the small elevations in ruminal digestion, implying that metabolic regulation was modifying intake of low-quality forage.     

Influence of fish meal and supplemental fat on performance of finishing steers exposed to moderate or high ambient temperatures.

Ninety-six Hereford x Angus steers (mean initial BW = 295 kg) were used in two growth experiments conducted at moderate and high ambient temperatures (AT), 48 steers per AT. Within each AT, calves were assigned to six dietary treatments consisting of a basal diet (approximately 60% corn and 20% grass hay) supplemented with either 0, 2.5, or 5% fat and with either soybean meal (SBM) or Menhaden fish meal (FM) included at levels such that a ratio of 16.3 kcal of NEm per kilogram of CP was maintained. Blood and ruminal fluid were collected 40 d before slaughter. During the final 28 d of the moderate AT experiment, apparent digestibility of dietary components was measured in four individually fed steers from each dietary treatment. Steer ADG was not affected by fat, and DMI and efficiency of gain were not affected (P > .10) by treatment. Average daily gain was lower for steers fed FM than for those fed SBM at moderate AT but higher at high AT (CP source x AT interaction; P < .05). Ruminal ratio of acetate to propionate declined linearly with increasing fat at moderate AT but was not affected by fat at high AT (fat x AT interaction trend; P = .08). Plasma urea N concentration increased linearly (P < .05) with increasing fat and was higher (P < .05) in steers kept at high than in those kept at moderate AT. Although apparent digestibility was not altered in steers fed FM, DM and NDF (P < .05) and ADF (P = .07) digestibility decreased with increasing fat in steers fed SBM (CP source x fat interaction).(ABSTRACT TRUNCATED AT 250 WORDS)