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Two experiments were conducted to evaluate perennial ryegrass straw as a forage source for ruminants. Experiment 1 evaluated digestion and physiological variables in steers offered perennial ryegrass straw containing increasing levels of ergot alkaloid, lolitrem B. Sixteen ruminally cannulated Angus x Hereford steers (231 [+ or -] 2 kg BW) were blocked by weight and assigned randomly to one of four treatments. Steers were provided perennial ryegrass straw at 120% of the previous 5-d average intake. Before straw feeding, soybean meal was provided (0.1% BW; CP basis) to meet the estimated requirement for degradable intake protein. Low (L) and high (H) lolitrem B straws (2,000 ppb) and low ( Key Words: Alkaloid, Beef Cattle, Endophyte, Lolitrem B, Perennial Ryegrass, Straw

Seven cannulated (rumen and duodenal) Angus x Hereford steers (264 [+ or -] 8 kg BW) consuming low-quality forage (5% CP; 61% NDF; 31% ADF) were used to determine the influence ofCP degradability and supplementation frequency (SF) on DMI and nutrient digestion. Treatments included an unsupplemented control and degradable intake protein (DIP) or undegradable intake protein (UIP) provided daily, every 3 d, or every 6 d. The DIP treatments (18% UIP) were calculated to provide 100% of the DIP requirement, while the UIP treatments (60% UIP) were provided on an isonitrogenous basis compared with DIP. Forage DMI was not affected by treatment. Total DM and N intake, duodenal N flow, and intestinal N disappearance increased (P < 0.01) with supplementation. Dry matter intake and duodenal N flow responded quadratically (P < 0.04; greatest values on the every-third-day treatments) as SF decreased. However, no differences in N intake or intestinal N disappearance were observed because of CP degradability or SF. Duodenal bacterial N flow and true bacterial N synthesis (g bacterial N/kg of OM truly digested in the rumen) were increased (P < 0.05) with supplementation. Also, duodenal bacterial N flow was greater (P < 0.05) for DIP compared with UIP. Duodenal nonbacterial N flow was increased (P = 0.02) with CP supplementation and for UIP compared with DIP (P < 0.01). Supplemental CP increased (P < 0.01) total tract DM and N digestibility with no difference due to CP degradability or SF. Results suggest CP supplements consisting of 20 to 60% UIP can be effectively used by steers consuming low-quality forage without adversely affecting DMI, nutrient digestibility, or bacterial CP synthesis, even when provided as infrequently as once every 6 d. Key Words: Degradation, Digestion, Forage, Frequency, Protein, Feed Supplementations

Seven ruminally and duodenally cannulated steers (264 [+ or -] 8 kg BW) consuming low-quality forage (5% CP; 61% NDF; 31% ADF) were used to determine the influence of CP degradability and supplementation frequency (SF) on ruminal fermentation characteristics. Treatments included an unsupplemented control and degradable intake protein (DIP) or undegradable intake protein (UIP) provided daily, every 3 d, or every 6 d. The DIP treatments (18% UIP) were calculated to provide 100% of the DIP requirement, while the UIP treatments (60% UIP) were provided on an isonitrogenous basis compared with DIP. Ruminal NH3-N was increased on the day all supplements were provided with supplemental CP (P = 0.04) and for DIP compared with UIP (P < 0.01). Also, because ruminal NH3-N increased at a greater rate with DIP compared with UIP as SF decreased, a linear effect of SF x CP degradability interaction (P = 0.02) was observed. In addition, NH3-N was greater on the day only daily supplements were provided for supplemented treatments (P = 0.04), and decreased linearly (P < 0.01) as SF decreased. Concentration of total VFA increased linearly (P = 0.02) as SF decreased on the day all supplements were provided, whereas on the day only daily supplements were provided, total VFA were greater for UIP compared with DIP (P = 0.01), and decreased linearly (P < 0.01) as SF decreased. An interaction concerning the linear effect of SF and CP degradability (P = 0.02) was observed for ruminal liquid volume on the day all supplements were provided. This was the result of an increase in liquid volume with DIP as SF decreased compared with a minimal effect with UIP. In contrast, there was no influence of supplementation on liquid volume the day only daily supplements were provided. Ruminal liquid dilution rate was greater (P = 0.02) with CP supplementation on the day all supplements were provided. We did observe a quadratic effect of SF x CP degradability interaction (P = 0.01) for dilution rate because of a quadratic response with DIP (greatest value with the every-third-day treatment) compared with a decrease as SF decreased for UIP. On the day only daily supplements were provided, ruminal liquid dilution rate decreased linearly (P = 0.02) as SF decreased. These results suggest that DIP and UIP elicit different effects on ruminal fermentation when supplemented infrequently to ruminants consuming low-quality forage while not adversely affecting nutrient intake and digestibility. Key Words: Degradation, Fermentation, Forage, Frequency, Protein, Supplements

Two studies were conducted to determine the influence of CP degradability and supplementation frequency (SF) on ruminant performance and N efficiency. Treatments included an unsupplemented control (CON) and degradable intake protein (DIP; 82% of CP) or undegradable intake protein (UIP; 60% of CP) provided daily, every 3 d, or every 6 d. Seven wethers (36 [+ or -] 1 kg BW) were used in the digestibility study with DIP and UIP treatments formulated to meet CP requirements. Eighty-four Angus x Hereford cows (512 [+ or -] 42 kg BW) in the last third of gestation were used for the performance study. The DIP treatments were calculated to provide 100% of the DIP requirement and UIP treatments were provided on an isonitrogenous basis compared with DIP. Basal diets consisted of low-quality (5% CP) meadow hay. Forage DMI and N intake by lambs decreased (P < 0.05) linearly as SF decreased. Additionally, DMI, OM intake, N retention, N digestibility, and digested N retained were greater (P < 0.01) for supplemented wethers than for controls with no difference due to crude protein degradability. Nitrogen balance, DMI, and OM intake decreased linearly (P < 0.05) as SF decreased. Plasma urea (PU; mM) was measured over a 6-d period and supplemented lambs had increased (P < 0.01) PU compared with CON. Plasma urea linearly decreased (P < 0.01) as SF decreased. Pre- and postcalving (within 14 d and 24 h of calving, respectively) cow weight and body condition score change were more positive (P < 0.05) for supplemented groups than for controls. Results suggest CP supplements consisting of 20 to 60% UIP can be effectively used by ruminants consuming low-quality forage without adversely affecting N efficiency and animal performance, even when provided as infrequently as once every 6 d. Key Words: Degradability, Frequency, Nitrogen, Protein, Ruminants, Supplementation

The objective of this study was to test the combined effect of offstream water and trace mineral salt on cattle distribution in a riparian meadow and its adjacent uplands. From July 15 to August 26, 1996 and 1997, three treatments were each randomly assigned to one pasture in each of three blocks. Sixty cow/calf pairs were then randomly allotted to the grazed pastures. The treatments included 1) stream access and access to offstream water and trace-mineral salt (offstream), 2) stream access and no access to offstream water or trace-mineral salt (no-offstream), and 3) ungrazed control. The response of cattle was measured through visual observations of cattle distribution, grazing activity and travel distance, cow/calf performance, and fecal deposit distribution. Distribution patterns of the cattle, measured as the distance of cattle from the stream, was characterized by a time of day x treatment x time in grazing period x year interaction (P < 0.05). No-offstream cattle began the day further from the stream than offstream cattle but consistently moved closer to the stream after the morning grazing period (0600 to 0900). Differences in distribution patterns between the two treatments were more pronounced early in the grazing period than late in the grazing period. Grazing activity, fecal deposit distribution, and travel distance of cattle were not affected by the presence of offstream water and trace-mineral salt. Cows and calves with offstream water and trace-mineral salt gained 11.5 kg and 0.14 kg/d more, respectively, than no-offstream cows and calves averaged across years (P < 0.05). Overall, cattle distribution patterns and cow/ calf performance were influenced by the presence of offstream water and trace-mineral salt. Changes in distribution were most pronounced early in the grazing season. Key Words: Behavior, Distribution, Grazing, Livestock, Riparian Grassland, Water

Two studies were conducted to evaluate high-quality tall fescue hay as a supplement to beef cattle fed low-quality roughages. In Exp. 1, 15 ruminally cannulated Hereford x Angus steers (average weight 390 kg) were blocked by weight and assigned randomly to one of three treatments: 1) tall fescue straw, no supplement; 2) tall fescue straw plus tall fescue hay supplement; 3) tall fescue straw plus alfalfa hay supplement. The 28-d digestion study consisted of 14 d of adaption, 6 d of intake data, and 6 d of collection of feces, respectively, with a 1-d ruminal sampling (d 27) and ruminal evacuations (d 28). In Exp. 2, 90 gestating Hereford x Angus cows were stratified by age and body condition and, within stratum, assigned randomly to three replications of the same treatments as described for Exp. 1. In both studies, a basal diet of tall fescue straw was fed with ad libitum access, alfalfa hay was fed at .4% BW, and tall fescue hay was fed at a level isonitrogenous with the alfalfa hay (.61% BW). In Exp. 1, DMI was at least 13% greater (P < .01) for supplemented steers than for nonsupplemented steers and was 12% greater (P < .10) for steers receiving supplemental tall rescue hay than for alfalfa hay-supplemented steers. Digestibility of DM was greater for supplemented steers than for nonsupplemented steers (P < .05) and, between supplement treatments, greater for tall fescue hay-supplemented steers than for alfalfa hay-supplemented steers (P < .10). Ruminal ammonia values peaked at 3 h after feeding and were higher for steers fed supplement treatments than for those fed the control treatment from just before feeding through 6 h after feeding (P < .10). In Exp. 2, supplemented cows gained more BW than nonsupplemented cows (P < .01), and the tall fescue hay-supplemented cows gained more BW (P < .10) than cows supplemented with alfalfa hay. Likewise, supplemented cows lost less condition (P < .01) than their nonsupplemented counterparts during the 84-d supplementation period, and cows receiving tall fescue hay supplement tended (P = .23) to lose less condition than cows receiving alfalfa hay supplement. No differences in calf growth were noted among treatment groups (P < .10). In conclusion, supplementation of high-quality tall fescue hay to cows fed low-quality forage diets seems to result in performance that is similar to or better than that of cows receiving alfalfa hay supplements when fed on an isonitrogenous basis. Key Words: Beef Cattle, Supplementation, Tall Fescue Hay, Alfalfa Hay

Two experiments were conducted to compare whole, raw soybeans (WSB), extruded soybeans (ESB), and soybean meal + barley (SBM+BAR) as supplemental protein sources for growing beef steers consuming low-quality, mature grass hay (6.5% CP). In Exp. 1, a 23-d digestion study, four ruminally cannulated steers were assigned to the following treatments in a 4 x 4 Latin square design: 1) control, no supplement; 2) 1.5 kg|center dot~|animal.sup.-1~|center dot~|d.sup.-1~ of WSB; 3) 1.36 kg|center dot~|animal.sup.-1~|center dot~|d.sup.-1~ of ESB; and 4) 1.48 kg|center dot~|animal.sup.-1~|center dot~|d.sup.-1~ of 62%:38% SBM+BAR. Apparent DM digestibility was increased by supplementation (P |is less than~ .10), but NDF digestibility was not changed (P |is greater than~ .10). No differences in digestibility were observed among supplement treatments (P |is greater than~ .10). In situ rate and extent of supplement CP disappearance in Dacron bags did not differ among supplements (P |is greater than~ .10), but extent of DM disappearance was greater for WSB than for ESB (P |is less than~ .10). In situ rate of forage NDF disappearance was decreased by protein supplementation (P = .10). In Exp. 2, 40 Polled Hereford and Red Angus x Simmental weanling steer calves were stratified by weight (average BW, 250 kg) and allotted randomly to one of two replications of the four treatments used in Exp. 1 (eight pens, five animals per pen). Forage DMI was not affected by treatment (P |is greater than~ .10). Average daily gain and feed efficiency were increased by supplementation (P |is less than~ .05). Supplement source had no effect on intake or ADG (P |is greater than~ .10), but ESB tended to exhibit better feed efficiency than WSB (P = .10). In conclusion, WSB and ESB seem to be as effective as SBM+BAR protein supplements for growing beef cattle. In addition, WSB and ESB, at the levels used in these experiments, can be incorporated into diets for cattle consuming low-quality roughage without deleterious effects on fiber digestion or subsequent performance.

Two experiments (Exp) were conducted to determine the influence of CP degradability (CPD) and supplementation frequency (SF) on performance and N efficiency of ruminants consuming low-quality meadow hay (5% CP). Treatments (TRT) included an unsupplemented control (CON) and degradable intake protein (DIP; 18% UIP) or undegradable intake protein (UIP; 60% UIP) provided daily, every 3 d, or every 6 d. Exp 1 was a N balance study using 7 wethers (36 [+ or -] 1 kg BW) with DIP and UIP TRT formulated to meet CP requirements. Exp 2 was a performance study using 84 cows (512 [+ or -] 42 kg BW) during the last third of gestation. Supplements were formulated so that the DIP TRT provided 100% of DIP requirement while UIP TRT were isonitrogenous compared with DIP TRT. In Exp 1 forage DMI and N intake decreased (P < 0.05) linearly as SF decreased. Dry matter intake, N balance, N digestibility, and digested N retained were greater (P < 0.01) for supplemented wethers compared with CON, with no difference (P > 0.10) due to CPD or SF. Nitrogen balance decreased linearly (P < 0.05) as SF decreased. Plasma urea (PU; mM), measured over a 6 d period, increased (P < 0.01) with supplemented lambs compared with CON. In addition, PU linearly decreased (P < 0.01) as SF decreased. In Exp 2 cow pre- and post-calving (within 14 d and 24 hr of calving, respectively) BW and BCS change were improved (P < 0.05) for supplemented groups compared with CON. No differences (P > 0.10) were observed for CPD or SF. Our results suggest CP supplements consisting of 20 to 60% UIP can be effectively used by ruminants consuming low-quality forage without adversely affecting N efficiency and animal performance, even when provided as infrequently as once every 6 d. Key Words: Protein Degradability, Nitrogen, Supplementation Frequency

Seven cannulated (rumen and duodenal) steers (264 [+ or -] 8 kg BW) were used to determine the influence of CP degradability (CPD) and supplementation frequency (SF) on DMI, ruminal fermentation, and nutrient digestion of low-quality forage (5% CP). Treatments (TRT) included an unsupplemented control and degradable intake protein (DIP) or undegradable intake protein (UIP) provided daily, every 3 d, or every 6 d. The DIP TRT (18% UIP) were calculated to provide 100% of the DIP requirement while the UIP TRT (60% UIP) were provided on an isonitrogenous basis compared with DIP TRT. Forage DMI was not affected (P > 0.10) by TRT. Total DM and N intake, duodenal N flow, and intestinal N disappearance increased (P < 0.01) with supplementation. No differences in DMI, N intake, duodenal N flow, or intestinal N disappearance were observed due to CPD or SF (P > 0.10). Supplemental CP increased (P < 0.01) total tract DM and N digestibility with no difference (P > 0.10) due to CPD or SF. Rumen fluid was collected 0, 3, 6, 9, 12, and 24 h after feeding on the d of and d before supplementation for all TRT. Ammonia N (mM) increased (P < 0.05) the d of and the d before supplementation for all protein TRT. However, a CPD x SF interaction (P < 0.05) on the d of supplementation indicated that N[H.sub.3] N increased at a greater rate for DIP as SF decreased compared with UIP. Ammonia N linearly decreased (P < 0.01) as SF decreased the d before supplementation. Results suggest CP supplements consisting of 20 to 60% UIP can be effectively used by steers consuming low-quality forage without adversely affecting DMI and nutrient digestibility, even when provided as infrequently as once every 6 d. Key Words: Protein, Degradability, Supplementation frequency

Sixty-four beef heifers (287 [+ or -] 2 kg) and 4 ruminally cannulated steers (286 [+ or -] 4 kg) were used in an 84-d study to evaluate beet pulp (BP) supplementation of early-to-mid season native flood meadow pasture. Treatments (TRT) consisted of an unsupplemented control (CON) and 0.25 (L), 0.50 (M), and 0.75 (H) kg/d dried BP. Heifers were gathered daily at 0730 from a common 35 ha pasture and sorted into pens (4 heifers/pen; 4 pens/TRT) and provided BP. After the BP was consumed (approximately 3 hr) heifers were returned to the common native flood meadow pasture. Heifers were weighed every 28 d and available forage determined by clipping 25 randomly placed 0.19-[m.sup.2] quadrats. In addition, rumen fluid was obtained via stomach tube on d 42 from one heifer randomly selected from each pen 4 hr after supplementation. Cannulated steers were used to estimate diet quality on d 0, 28, 56, and 84 by rumen evacuation/masticate collection procedures. Diet quality estimates were 23, 18, 15, and 12% CP and 44, 49, 53, and 58% NDF for d 0, 28, 56, and 84, respectively. Heifer ADG was not affected (P > 0.10) by BP supplementation (1.11, 1.08, 1.04, and 1.08 kg/d for CON, L, M, and H, respectively). In addition, ruminal N[H.sub.3] N and pH were not altered (P > 0.10) by BP supplementation. These data suggest that BP is not a beneficial supplement to growing beef heifers consuming high-quality native flood meadow. Key Words: Beet Pulp, Supplementation, Performance

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% CO). 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%, 178% 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. Key Words: Beef Cattle, Supplements, Alfalfa Hay, Roughages

Abstract: A series of experiments were conducted to quantify PGF2α in bovine semen, seminal plasma, and extended semen, and to determine if PGF2α was synthesized or released during extension of bovine semen. Concentrations of PGF2α were measured in paired samples of whole and extended semen from beef and dairy bulls. Concentrations of PGF2α did not differ between beef and dairy (mean ± SEM, 273.8 ± 42.8 vs. 210.3 ± 18.5 pg/mL, respectively; P = 0.12), but tended (P = 0.08) to be greater for whole compared with extended semen (255.5 ± 29.8 vs. 194.5 ± 17.0 pg/mL). Whole semen was extended at eight dilution rates (regardless of initial sperm concentration), using a diluent consisting of two fractions. Samples collected after each dilution step resulted in four subsamples. Concentrations of PGF2α in subsamples decreased (P < 0.001) at higher dilution rates and later steps of extension. Subsequently, whole semen and seminal plasma were extended at three dilution rates. Initial PGF2α concentration was greater (P < 0.001) for whole semen compared with seminal plasma. During extension, PGF2α synthesis or release resulted in less disparity, but the amount synthesized or released was greater (P = 0.03) for semen compared with seminal plasma. We concluded that synthesis or release of PGF2α during extension resulted in concentrations similar to whole semen. [Copyright &y& Elsevier]

Beef cattle distribution and use patterns are a continual challenge for livestock and land managers in the western US. Designing grazing management plans that optimize animal performance while maintaining or improving native vegetation are critical goals of land managers. To achieve these goals, the manager needs to understand how biotic (cow age, breed, stage of production, experience, etc) and abiotic (slope, aspect, vegetation type, soil depth, etc.) factors influence grazing distribution and diet selection. Pasture distribution and diet selection of beef cattle are influenced by the animal's nutritional requirements and the availability, palatability, and nutritional quality of the vegetation. The availability of water and the diurnal pattern of grazing relative to water location clearly illustrate the importance of water and associated vegetation in beef cattle thermal regulation and grazing distribution. However, the role of vegetation quality (CP, NDF, ADF, IVDMD, and DM), in predicting beef cattle distribution and use patterns, is less clear. In comparison to other herbivores, cattle have strong preferences for herbaceous vegetation even when woody vegetation is superior in nutrient density. Changes in vegetation are a function of landscape characteristics and, as a result, are often confounded with attributes such as elevation, topography, aspect, slope, and surface water. Past research has documented grazing behavior differences due to breed, age, and lactation status, suggesting that beef cattle nutrient requirements also influence grazing distribution and use patterns. [ABSTRACT FROM AUTHOR]