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Tall fescue (Schedonorus arundinaceus) is a cool-season perennial grass that is widely used as a forage for many livestock species including sheep. An endophyte (Neotyphodium coenophialum) in tall fescue produces ergot alkaloids that enhance plant survival but produce toxicosis in animals. The objective of this study was to investigate the rumen microbiota from gestation and lactation in ewes grazing tall fescue pastures with high (HA) or moderate (MA) levels of endophyte infection, and their relationship with serum parameters. Data were collected at the beginning of the study (d1), the week before initiation of lambing (d51), and at the end of the trial (d115). The rumen microbiota was evaluated using 16S rRNA gene sequencing. Ewes grazing HA had greater serum non-esterified fatty acid (NEFA) (P = 0.024) levels compared with ewes in MA pasture at d115. Both the number of observed OTUs and Shannon diversity index tended (P = 0.08, P = 0.06) to be greater for HA than for MA on d115. At the genus level, Prevotella relative abundance increased with time in both MA and HA (on d1, d51 and d115: 15.17%, 25.59% and 24.78% in MA; 14.17%, 18.10% and 19.41% in HA). Taxa unclassified at the genus level including (unclassified) Lachnospiraceae, Coriobacteriaceae and Veillonellaceae exhibited higher abundances in HA at d51 (3.72%, 2.07% and 11.22%) compared with MA (2.06%, 1.28% and 7.42%). The predictor microbiota for HA and MA were identified by a random forest classification model. The HA predictors included bacteria associated with unclassified Coriobacteriaceae and Ruminococcaceae. Other OTUs classified as Prevotella and Clostridiales could be microbial predictors for MA. The OTUs classified as Prevotella and Lachnospiraceae were negatively correlated with serum concentration of prolactin. Negative correlations with NEFA were observed in the microbiota such as species affiliated to unclassified Clostridiales and Prevotella. OTUs classified as Bacteroidetes and Coriobacteriaceae exhibited a positive correlation with NEFA. Our study confirmed that the rumen microbiota populations were affected by high levels of toxins in endophyte-infected tall fescue and were associated with host hormone and energy metabolism.

Forage for grazing and hay may be limited during drought years, necessitating alternative feeding options. Co-product feedstuffs, such as soybean hulls (SH), may be a more economical means to maintain cows through such conditions. The objective of this study was to determine if SH could be used to meet the majority of the energy demands for cows in late gestation when access to hay was restricted to 1 h daily. Eighty-six gestating, spring-calving cows (527 ± 7.5 kg initial BW; 4.3 ± 0.27 yr of age) were allocated to 1 of 6 groups for a 68-d study beginning December 6, 2012. Three groups were given ad libitum access to medium-quality bermudagrass [Cynodon dactylon (L.) Pers.] hay. The 3 remaining groups were offered 6.4 kg of SH/cow daily and allowed access to a very-poor-quality, mature, mixed-grass hay for only 1 h daily. Each group was housed in separate 2.02-ha dormant bermudagrass pastures. Birth weight and dystocia scores were recorded, and calf performance was monitored through weaning. Representative bales of each hay were weighed to determine total hay offered. Differences in BW and BCS, and changes in these measurements during the study, were minimal between treatments (P ≥ 0.53). Calf birth weight, weaning weight, BW/d of age at weaning, and birth-to-weaning ADG did not differ (P ≥ 0.11) between treatments. Therefore, SH may be used as the major dietary energy component for cows in late gestation having access to hay for only 1 h daily without having adverse effects on the cows or their subsequent calves.

Negative effects on cattle grazing tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] infected with the wild-type endophyte Neotyphodium coenophialum (E+) are well documented, but information about the carryover effects on weaned calves is limited. Our objective was to compare pre- and postweaning performance by spring-calving cows and calves grazing E+ with that by cows grazing a nontoxic endophyte–tall fescue association (NE+). Pregnant Gelbvieh × Angus crossbred cows (n = 136; 492 ± 19.2 kg of initial BW) were stratified by BW and age and allocated randomly to one of four 10-ha pastures in yr 1 (October 15) and one of eight 10-ha pastures in yr 2 (November 30). Pastures were allocated randomly before establishment to E+ or NE+. Cows remained on their assigned pastures until weaning in yr 2 but were removed from NE+ in the summer of yr 1 because of low forage mass. After weaning, calves grazed bermudagrass [Cynodon dactylon (L.) Pers.] followed by cool-season annual grasses. Cow BW and pregnancy rate, and calf weaning weight and preweaning gain were greater (P < 0.05) from NE+ versus E+. Weaning weight differentials were maintained throughout postweaning production phases, resulting in heavier HCW (P < 0.05) by steers and a tendency for greater (P < 0.10) subsequent calving rates by heifers. Therefore, replacing E+ with NE+ may improve preweaning cow and calf performance and heifer reproductive rates, but postweaning gains may not be affected by previous exposure to E+.

The objective of these experiments was to determine the effect of daily or alternate day supplementation of dried distillers grains with solubles (DDGS) with or without monensin on performance of grazing calves. Treatments included (1) a negative control with no supplemental feed except free-choice mineral; (2) DDGS offered daily at 1.02 kg as-fed per calf, including a mineral premix; (3) daily DDGS and monensin (Rumensin, Elanco, Greenfield, IN) at 1.02 kg as-fed per calf, including a mineral premix supplying 160 mg of monensin/calf daily; (4) alternate day DDGS to supply 2.04 kg as-fed per calf, including the mineral premix offered on alternate days; and (5) alternate day DDGS and monensin to supply 2.04 kg as-fed per calf, including a mineral premix and 320 mg of monensin/calf on alternate days. Four experiments were conducted which included both steers (n = 70) and heifers (n = 230) grazing warm season grass based pastures (Exp. 1, 2, and 3) or nontoxic endophyte-infected tall fescue (Exp. 4). Supplementation increased ADG (P ≤ 0.04) by 0.16 to 0.26 kg/d in the 4 studies, with an average improvement (P

A total of 120 Gelbvieh × Angus crossbred heifers (552 ± 2.5 lb initial BW) grazed pastures of common bermudagrass [Cynodon dactylon (L.) Pers.] overseeded with wheat (Triticum aestivum L.) and annual ryegrass (Lolium multiflorum Lam.) for a 3-year study to compare the effect of seeding dates and tillage intensities on heifer growth performance. Half of the pastures were seeded in early September (Early) and half in mid October (Late). Within seeding date, half of the pastures were disked once (1×) and half were disked twice (2×) before seeding. Grazing began when forage mass reached approximately 2000 lb/acre and continued through 11 May 2002 (year 1), 25 April 2003 (year 2), and 10 May 2004 (year 3). Forage mass was greater from Early than from Late seeded pastures for 2 of the first 3 months of grazing resulting in 17-day earlier grazing initiation and approximately 165 lb less hay fed per heifer. Total body weight gain, or gain while grazing cool-season annuals did not differ between seeding dates or tillage intensities. Producers in the Mid South region with bermudagrass pastures may have considerable flexibility in their decisions as to when to seed annual forages and to what intensity they till their sod depending upon how soon they need available forage.

Tall fescue toxicosis adversely affects calving rate and weight gains reducing returns to cow-calf producers in the south–central United States. This grazing study estimated animal and economic performance implications of endophyte-infected fescue and calving season. Establishing novel endophyte-infected tall fescue on 25% of pasture acres resulted in improved calving rates (87% vs. 70%), weaning weights (532 lbs vs. 513 lbs), and partial returns per acre ($257 vs. $217). Additionally, fall-calving cows had higher calving rates (91% vs. 67%), weaning weights (550 lbs vs. 496 lbs), and partial returns per acre ($269 vs. $199) than spring calving cows.

a b s t r a c t Bermudagrass (Cynodon dactylon (L.) Pers.) is commonly used for grazing and haying in the southern USA, but hay curing can be challenging due to frequent rainfall events dur- ing spring and early summer. An existing stand of 'Greenfield' bermudagrass was divided into 12 plots using a randomized complete block design with a 2×2 factorial treatment arrangement to evaluate the influence of a non-viable Lactobacillus-lactic acid preservative and moisture concentration at baling on chemical composition, intake by sheep, and in situ disappearance in cattle. At time of mowing, half of the plots in each block were either spray-treated (T) or not treated (U) with 81 mL/t forage dry matter (DM) of the preser- vative solution. Hay was then baled at target moisture concentrations of either 174 g/kg DM (L) or 267 g/kg DM (H). Maximum temperature and heating degree days were greater (P 0.10). Post-storage nutritive value was largely influenced by moisture treatments only. Intake and digestibility, and in situ DM dis- appearance of these same hays were determined using 16 wether lambs (43 ± 3.7 kg initial BW), or six ruminally cannulated cows (617 ± 3.5 kg initial BW), respectively. Dry matter intake by sheep was not affected by either treatment factor (P>0.05), but DM digestibil- ity and digestible DM intake were greater (P

Relating single-nucleotide polymorphisms (SNP) to cows with acceptable productivity could benefit cattle breeders in areas where tall fescue is the predominant forage. This study aimed to (i) identify SNPs in bovine cytochrome P450 3A28 (CYP3A28) and (ii) determine the associations between SNP genotype, forage and cow body condition (BC). Genotype (CC, CG or GG) and forage [Kentucky-31 wild-type endophyte-infected tall fescue (KY+) vs. bermudagrass] effects on milk volume and quality were determined in Herd 1 cows (123 cows); in Herd 2 (99 cows), genotype and BC (low vs. moderate) effects on ovarian follicle size, calving date and calving per cent were determined; and in Herd 3 (114 cows), effects of genotype and fescue cultivar [KY+ vs. non-toxic endophyte-infected tall fescue (HiMag4)] were related to calving per cent, calving date and weaning weights of both cow and her calf. A cytosine (C) to guanine (G) transversion at base 994 (C994G) in CYP3A28 was identified. There was a genotype × forage type interaction (p < 0.05) on milk protein in Herd 1 cows; CC cows grazing bermudagrass had greater milk protein percentage in relation to other cows in the herd. In Herd 2, BC and genotype × BC tended (p < 0.10) to influence follicle size and Julian calving date respectively. Diameter of the largest follicle tended to be larger in moderate BC than in low-BC cows; whereas, CC and CG cows in moderate BC and homozygous (CC and GG) cows in low BC tended to calve 14 days earlier in relation to CG cows in low BC. In Herd 3, there was a genotype × forage type interaction (p < 0.05) on calving per cent, Julian calving date and calf weaning weight. In this study, genetic alterations (G allele at C994G) coupled with nutritional factors (low BC and toxic tall fescue) resulted in overall lower productivity in cows.

Fall-born calves grazing Neotyphodium coenophialum-infected tall fescue [E+; Lolium arundinaceum (Schreb.) Darbysh.] pastures should benefit from early weaning because of reduced exposure to fungal toxins. However, fall-born calves that grazed E+ and were weaned in mid-April had reduced post-weaning performance compared with calves managed similarly but weaned in early June. Gelbvieh × Angus calves (n = 238) were used in a 3-year study to determine the optimal time to wean fall-born calves grazing E+. Cow/calf pairs were allocated randomly to one of four weaning date treatments: 1) March 16 (177 ± 4.7 days of age; MarW), 2) April 13 (204 ± 4.7 days of age; AprW), 3) May 11 (236 ± 4.7 days of age; MayW), and 4) June 8 (264 ± 4.8 days of age; JuneW). On their assigned weaning date, calves were weighed, vaccinated, blood samples were collected, and calves were moved to 3.2-ha pastures adjacent to their dams for 14 days. After the weaning period, calves were weighed, blood samples were collected, and then calves were moved to pastures containing non-toxic forages. Birth weight and calf weights on MarW, AprW, and MayW weaning dates did not differ (P ≥ 0.21) across weaning date treatments. However, calf weaning weights on their respective weaning dates, weight on JuneW and on June 22 (14 days following the JuneW), daily gain between birth and June 22, and weight change between MarW and JuneW increased linearly (P

A number of studies have reported performance by spring-calving cows grazing Neotyphodium -infected fescue [E+, Lolium arundinaceum (Schreb.) Darbysh.], but post-weaning calf performance from the majority of those studies is limited. Furthermore, both pre- and post-weaning information pertaining to fall-calving cows and their calves grazing E+ is particularly limited. A 3-year study was initiated in April 2000 near Batesville, AR (USA) to investigate the impact of rotational management (twice monthly vs. twice weekly) program and weaning date [mid-April (EARLY) vs. early June (LATE)] on production of fall-calving cow-calf pairs grazing E+ overseeded with ladino ( Trifolium repens L.), and red clover ( Trifolium pretense L), lespedeza ( Lespedeza stipulacea Maxim.), and crabgrass ( Digitaria sanguinalis (L.) Scop.). A secondary objective of the study was to evaluate calf performance both at weaning and after weaning until either breeding of the heifers or slaughter of the steers. Calves weaned later had greater ( P P P P P P ≥ 0.11) from LATE in the other 2 years. Initial and final feedlot BW and gain did not differ ( P ≥ 0.16) among previous treatments in 2 of 3 years. Therefore, carryover effects of weaning date or rotational grazing on calves previously grazing E+ tall fescue may be mitigated during a subsequent backgrounding period such that impacts on subsequent breeding or feedlot performance is minimized.

Two tall fescue (Festuca arundinacea Schreb.) forages, one an experimental host plant/endophyte association containing a novel endophyte (HM4) that produces low or nil concentrations of ergot alkaloids, and the other a typical association of Kentucky 31 tall fescue and the wild-type endophyte (Neotyphodium coenophialum; E+), were autumn-stockpiled following late-summer clipping and fertilization with 56 kg/ha of N to assess the nutritive value and ruminal disappearance kinetics of autumn-stockpiled tall fescue forages. Beginning on December 4, 2003, sixteen 361 +/- 56.4-kg replacement dairy heifers were stratified by weight and breeding and assigned to one of four 1.6-ha pastures (2 each of E+ and HM4) that were strip-grazed throughout the winter. Pastures were sampled before grazing was initiated (December 4), each time heifers were allowed access to a fresh strip (December 26, January 15, and February 4), and when the study was terminated (February 26). For fiber components, there were no interactions between fescue type and sampling date for either pregrazed or postgrazed forages. Over sampling dates, neutral detergent fiber (NDF; 56.5 to 67.8%), acid detergent fiber (27.7 to 34.9%), hemicellulose (28.8 to 34.0%), cellulose (25.0 to 28.1%), and lignin (3.61 to 10.05%) varied with sampling date, but patterns were almost exclusively curvilinear with time. Ruminal disappearance rate of dry matter (DM) was not affected by any treatment factor (overall mean for both pregrazed and postgrazed forages = 0.050 h(- 1)); similar responses were observed for NDF disappearance (overall mean = 0.048 h(- 1)). Interactions of fescue type and sampling date were observed for both pregrazed and postgrazed forages with respect to effective ruminal disappearance of DM; however, estimates were relatively high for all forages (overall mean = 64.0%). Effective disappearance of NDF was relatively extensive for all forages (overall mean = 55.4% of NDF). Based on the results of this trial, the endophyte status of stockpiled tall fescue forages had little practical effect on forage nutritive value and kinetics of ruminal DM or NDF disappearance. Overall, autumn-stockpiled tall fescue forages would appear to be a legitimate and lower cost alternative to harvested forages, and appear to possess suitable nutritional characteristics for developing dairy heifers in the Ozark Highlands.

The economic impact of rotation frequency (twice weekly vs. twice monthly until time of weaning) and time of weaning (early April vs. 56 d later) was examined for fall-calving cows using a modified put and take grazing strategy implemented to maintain equal grazing pressure across production systems. Cow and/or calf death losses resulted in replacements with either bred cows or cow-calf pairs. While the analysis on heifer calves was limited to sale at time of weaning, steer calves were tracked through the feedlot stage to determine if the time of sale would alter production system recommendations. For the conditions presented in this study, cow-calf producers may be advised that (i) relative to late weaning, early weaned calves did not regain their weight disadvantage observed at time of weaning; (ii) more intensive pasture management (rotating twice weekly rather than twice monthly) was not worth the effort because partial return results for late-weaned steer and heifer calves did not differ statistically by rotation frequency, regardless of sale time; (iii) partial returns were highest for steer calves retained through the finishing stage at the feedlot (regardless of production system) compared with sale at the time of weaning or at the time of placement in the feedlot; (iv) the range of returns or financial risk exposure increased with length of calf ownership. However, use of long-term average prices excluded input price risk from the analysis and output price risk was only partially addressed.

A 4-yr trial was initiated in January 2000 to evaluate cow-calf performance on mixed-species pasture systems consisting of (i) endophyte-infected tall fescue (E+; Festuca arundinacea Schreb.) diluted by approximately 50% with common bermudagrass [Cynodon dactylon (L.) Pers.] and other forages; (ii) endophyte-free tall fescue (E-) overseeded into dormant common bermudagrass; and (iii) orchardgrass (OG; Dactylis glomerata L.) established under the same conditions as E-. The E- and OG pastures were grazed with either twice weekly (2W) or twice monthly (2M) rotation schedules, while pastures with E+ were grazed with 2M only. Actual weaning weights tended to be greater (P = 0.096), and age-adjusted 205-d weaning weights and average daily gain from birth to weaning were greater (P ≤ 0.035) for calves raised on low-toxicity (E - or OG) pastures compared to those raised on E+. Over 4 yr, calves raised on low-toxicity pastures exhibited 22- and 24-kg advantages in actual and 205-d adjusted weaning weights, respectively, compared to those raised on E+. Cows grazing OG and E- pastures exhibited greater (P ≤ 0.021) body weights and body condition scores (BCS) at calving than cows grazing E+ pastures. Furthermore, reductions in body weight and BCS between calving and weaning tended to be greater (P ≤ 0.088) for cows grazing E+ pastures. Calf performance was improved consistently by these low-toxidty pasture systems, but management requirements may limit adaptation by producers.

A grazing study was initiated in April 2000 and continued through three calving and weaning cycles (ending July 2003) to investigate the effects of rotational grazing management (twice monthly [2M] vs. twice weekly [2W]) and weaning date (mid-April [EARLY] vs. early June [LATE]) on production of fall-calving cow-calf pairs (495 +/- 9.6 kg initial BW) grazing Neotyphodium coenophialum-infected tall fescue (Festuca arundinacea Schreb.) overseeded with legumes and crabgrass. Secondary objectives of the experiment were to monitor differences in quantity and quality of available forage and to evaluate changes in forage species composition. Pastures were dominated by tall fescue throughout the study, and the proportion of basal cover was greater (P < 0.05) in 2M than in 2W pastures. The percentage of legumes was very low across all treatment combinations, but the percentage of crabgrass continued to increase (P < 0.05) linearly and quadratically across years for both summer and fall sampling periods, regardless of rotation or weaning program. In vitro DM disappearance and mineral concentrations varied minimally because of rotation frequency or weaning date. Rotation frequency did not substantially affect (P = 0.11 to 0.97) cow BW, hay offered, milk production, calving interval, calf birth weight, or actual or adjusted weaning weights; however, 2M cows had 0.3 units higher (P < 0.05) BCS at the time of breeding than 2W cows. Calves weaned late had greater (P < 0.05) actual weaning weight and weighed more (P < 0.05) on the LATE weaning date than on the EARLY weaning date, but 205-d adjusted weaning weights did not differ (P = 0.74) across weaning dates. Therefore, rotation frequency and/or weaning date had little effect on forage species composition or forage quality. In addition, the rapid rotation program offered little advantage with respect to animal performance, and weaning fall-born calves grazing endophyte-infected tall fescue pastures at approximately 189 d of age seemed to be detrimental to calf performance compared with delaying weaning until 243 d of age.

Autumn stockpiling is a management technique in which forage is allowed to accumulate throughout the late summer and early fall for subsequent grazing throughout the late fall and winter. Well-established stands of common and 'Tifton 44' bermudagrass [Cynodon dactylon (L.) Pers.] located at Fayetteville and Batesville, AR, respectively, were chosen to evaluate the effects of stockpiling initiation date (August or September) and N fertilization rate (0, 37, 74, or 111 kg N ha -1 ) on the canopy height and dry matter (DM) yield potential of autumn-stockpiled bermudagrass forage. Within year, DM yield increased linearly (P ≤ 0.008) with N fertilization rate at Fayetteville in 2001 and in Batesville during both years. For August initiation dates, DM yield declined linearly (P ≤ 0.007) with harvest date at both sites during both years; however, cubic responses (P ≤ 0.024) also were observed at both sites in 2000 but not (P ≥ 0.076) in 2001. For September initiation dates, DM yield exhibited less consistent patterns over harvest dates, but responses were cubic (P ≤ 0.053) over time for all four site-years. Tests of homogeneity for regressions of DM yield on canopy height for individual site-years indicated there were differences for the intercepts (P < 0.001) and linear coefficients (P < 0.001) and a tendency for the quadratic coefficients (P = 0.063) to differ. Quadratic equations are not suitable for producer use; therefore, a combined linear model for all data (N = 512) was determined, Y = 146x - 838 (P < 0.001; r 2 = 0.762), which may address the need for a quick estimator of available forage.

Ruminal in situ disappearance kinetics of nitrogen (N) in forages are frequently evaluated in confined animals, but there have been relatively few attempts to obtain these kinetic estimates from grazing animals. Our objectives were to evaluate the effects of harvest technique and sampling date on the in situ N disappearance kinetics and nutritive value of wheat ( Triticum aestivum L.) forage, and to compare in situ disappearance kinetics of N for these forages when the experimental steers were housed in confinement with those obtained from steers grazing wheat pasture. Wheat forages were harvested on three dates (March 6, March 27, and April 11, 2000) using five sampling techniques. These included three clipping techniques (whole plant, random pluck, and top half) and two evaluations of masticates (oven dried at 50 °C or lyophilized). Disappearance kinetics of N for the 15 experimental forages were evaluated by the in situ technique using five 393±54.4 kg crossbred steers that were offered an alfalfa based ( Medicago sativa L.) diet and were housed in confinement. Subsequently, this evaluation was repeated in five 448±48.6 kg crossbred steers grazing wheat pasture during March 2001. Kinetic parameter estimates obtained from grazing steers were regressed on those obtained from confined steers. A slope of unity and an intercept of zero is indicative of agreement between the two methods. For lag time and fractions A and B (i.e., portions of total N that are immediately soluble and that disappear at a measurable rate, respectively), the slopes and intercepts did not differ ( P ≥0.126) from unity and zero, respectively. For the disappearance rate ( K d ), the slope (0.92) did not differ ( P =0.408) from unity, but the intercept (0.027) was higher ( P =0.026) than zero. The slope (1.23) and intercept (−24.3% of N) for estimates of effective ruminal disappearance of N differed ( P ≤0.033) from unity and zero, respectively, but these differences were largely an artifact of the different ruminal passage rates used to calculate effective disappearance. From a practical standpoint, the in situ disappearance kinetics of N for these wheat forages were not altered substantially when they were obtained from grazing steers.

A 64-d grazing study was conducted with a 2 × 2 factorial arrangement of treatments to evaluate the impact of implant treatment on growth performance, hair score, and serum prolactin levels of steers grazing tall fescue with high (HE) or low (LE) levels of infection with the endophytic fungus Neotyphodium coenophialum. Mixed-breed steers (n = 130; 246 ± 3.5 kg initial BW) were allocated randomly to one of three HE or one of four LE pastures beginning April 13. Within each replication, one-half of the steers were implanted (IMP) with trenbolone acetate (40 mg) and estradiol (8 mg), and one-half were not implanted (NI). No implant treatment × endophyte level interactions were detected (P>0.10). Steers grazing HE had lower (P 0.10) between IMP and NI steers on either d 36 or 64. When tabulated across forage and implant treatments, correlations were negative between overall BW gains and hair scores measured on d 64 (r = 0.28; P

Magnesium supplementation has been shown to benefit feedlot cattle and is typically added at high concentrations to mineral supplements for calves grazing wheat pasture. Two experiments were conducted to determine the effects of Mg-mica supplementation on performance and serum mineral concentrations of stocker calves grazing wheat pasture. Supplemental Mg was provided at 6.1 g/d of supplemental Mg/ animal, Monday through Friday. In Exp. 1, 36 mixed-breed stocker calves (243 ± 3.9 kg BW) were stratified by BW and gender and allocated randomly to one of nine groups of four animals for a 112-d grazing study. Weight gain, shrink percentage, and serum Mg, Ca, K, Cu, and Zn concentrations did not differ (P>0.10) among calves fed either weathered Mg-mica (WMM), unweathered Mg-mica (UMM), or MgO. All serum mineral concentrations were within normal physiological ranges. In Exp. 2, 64 mixed-breed stocker steers (275 ± 1.7 kg BW) were stratified by BW and allocated randomly to one of 16 groups of four animals. Weight gain during a 50-d grazing study and subsequent feedlot period did not differ (P>0.10) among calves fed either no added Mg source or WMM, UMM, or MgO. Serum Cu was higher (P

Two experiments were conducted to determine the effects of Mg-mica supplementation on grazing and feedlot performance of stocker steers. In Exp. 1, eight groups of six steers were fed a basal diet of 80% ground grain sorghum, 15% corn silage, and 5% control protein supplement (DM basis) or a supplement containing Mg-mica (9% of supplement; 4.5 mg/kg diet DM) for 141 d. Marbling scores tended (P 0.10) higher marbling scores, and a higher percentage of carcasses grading USDA Choice than steers fed the control supplement during the pasture phase. Therefore, adding Mg-mica to pasture supplements or feedlot diets appears to have no impact on grazing or feedlot performance, but may improve carcass quality.

Bermudagrass [Cynodon dactylon (L.) Pers.] is productive in summer but dormant for much of the year in the central USA. The grazing season for bermudagrass can be lengthened with fall-interseeded small grains, which provide forage for early-season grazing. We compared forage yield and quality of rye (Secale cereale L., two cultivars), wheat (Triticum aestivum L., three cultivars), and barley (Hordeum vulgare L., one cultivar) when interseeded into bermudagrass sod or grown in monoculture. Field plots of each small grain were harvested two to four times each season and analyzed for in vitro dry matter digestibility (IVDMD) and crude protein (CP). Cumulative forage production for early spring (growing degree days [GDD] 1000) production of barley was usually greater than that of rye, but wheat cultivars were more balanced in seasonal production. Total forage production among small grains was often similar within each system, but the monoculture system had an almost threefold advantage. Although cultivars varied for IVDMD in the monoculture system, comparisons of digestible dry matter (DDM) were more consistent among harvests. Early DDM production of barley was usually lowest among the species, but as high or higher than other species for ryes. Concentrations of CP were variable, but relative CP production and yield had similar trends. In this study, rye was the best-suited species for interseeding in bermudagrass for early-season forage in grazing systems.

Generally, grazing endophyte-infested tall fescue (Festuca arundinace Schreb.) in the late spring and summer is not recommended because of the effects of fescue toxicosis on cattle weight gains, which can be extreme. For steers conditioned to graze tall fescue in the early spring, stocking rate (3, 4, 5, and 6 steers/ha) effects were evaluated for two methods designed to avoid poor cattle performance during the late spring and summer (compensation period). The evaluation was conducted in 1997 and 1998. During the compensation phase, one replicate of each stocking rate was randomly assigned to 1-ha pastures of eastern gamagrass (Tripsacum dactyloides L.), and the other replicate of each stocking rate remained on tall fescue; the steers were fed a 1:1 mixture of broiler litter and corn at 2.27 kg as fed/steer per d. Average daily gain for steers fed eastern gamagrass during the compensation phase declined linearly (P

Eastern gamagrass [Tripsacum dactyloides L.] is a native, warm-season, perennial, bunch-type grass adapted generally to moist sites throughout much of the eastern United States. Nitrogen concentrations of eastern gamagrass will normally exceed 20 g/kg at growth stages (boot and anthesis) that produce reasonable yields. With moderate N fertilization, concentrations of N approaching 32 g/kg are realistic in whole-plant tissue harvested at boot stage in the upper Midwest. Recent studies suggest that high proportions (>50%) of this N are insoluble in neutral detergent (NDIN), thereby implying association with the cell wall. In situ studies in Kansas have shown that the potential extent of ruminal N degradation for gamagrass harvested at boot stage is comparable with that of high quality legumes, but degradation occurs at slower rates; generally, similar trends have been observed for in situ disappearance of DM and fibrous components. Increasing plant maturity appears to limit extent primarily, but not the rate, of degradation for these plant components. Concentrations of NDF are generally high (>600 g/kg), even at immature growth stages; this observation is consistent with findings for other warm-season grasses. In studies conducted throughout the mid South, researchers report that ADG ranged between 0.5 and 1.0 kg/d for steers continuously grazing eastern gamagrass pastures. Daily gains are likely to be reduced as days on pasture increase. Mounting evidence suggests that gamagrass grown in the Midwest demonstrates better quality characteristics than that grown in the Southeast.

In complex landscapes with multiple land uses, it is often difficult to identify the source of contaminant loadings. The objective of this study was to compare nutrient runoff as affected by grazing animal depositions vs. poultry litter application. Simulated rainfall was applied twice to 1.5 by 6.0 m runoff plots of tall fescue (Festuca arundinacea Schreb.) with treatments of no waste (CT), dairy calf feces and urine (DFU), poultry litter (PL), and dairy calf feces and urine with poultry litter (DFU + PL). Chemical properties of the runoff samples including pH, electrical conductivity (EC), C, soluble reactive phosphorus (SRP), total nitrogen (TN), NH 4 -N, NO 3 -N, K, Mg, S, B, Cu, Fe, Mn, Mo, Na, and Zn were determined. Plots receiving poultry litter had significantly greater losses of most nutrient parameters for both rainfall simulations. For the nutrient parameters of primary interest with regard to water quality, 5.0, 29.5, and 21.9% of the TN, NH 4 -N, and SRP applied in the PL treatment were transported in runoff during the first rainfall simulation as compared to 3.9, 5.0, and 15.3%, respectively, for the DFU treatment. Comparable percentages of the applied nutrients were lost from the PL and DFU treatments even though the PL treatment, with the exception of NH 4 -N, provided at least six times the amount of each nutrient. A severe rainfall event shortly after poultry litter application produces significantly greater nutrient losses as compared to similar application of grazing animal depositions at the rates used in the experiment.

Some aspects of wheat pasture bloat have been researched extensively, but few studies have evaluated the effect of wheat type or variety on bloat. Eight Gelbvieh x Angus ruminally cannulated heifers (515 +/- 49 kg of BW) and 48 Angus heifers (238 +/- 12 kg of BW) grazed 1-ha pastures of hard-red or soft-red winter wheat (Triticum aestivum L.) to evaluate the effect of wheat variety on bloat potential. In Exp. 1, cattle grazed from November 11 to 22 and from November 26 to December 7, 2006, in a crossover design. In Exp. 2, cattle were shrunk for 20 h and then grazed from December 19 to 20, 2006, and from January 19 to 20, 2007. In both experiments, bloat was scored at 1000 and 1600 h daily. Rumen samples were collected at 0600, 1200, and 1800 h during each of the last 2 d of each period in Exp. 1 and during both days of each period of Exp. 2. Rumen samples were evaluated for pH, foam production and strength, and viscosity. In Exp. 1, cannulated heifers grazing soft-red had a greater (P < 0.01) percentage of observed bloat (21.9 vs. 5.6%) than those grazing hard-red winter wheat, but bloat incidence was low (2.1%) for the stocker cattle, with no difference between hard-red and soft-red winter wheat (P = 0.52). Viscosity of the rumen fluid was affected (P = 0.03) by the wheat variety x time interaction, with soft-red at 1200 and 1800 h being more viscous than soft-red at 0600 h and hard-red at all times. Foam strength, as determined by bubbling CO(2) gas through rumen fluid, had a wheat variety x time interaction (P = 0.02) with both wheat varieties similar at 0600 h but soft-red having greater foam strength at 1200 and 1800 h. In Exp. 2, no bloat was observed, and no differences between wheat varieties were observed for any of the rumen foam measures. Therefore, for these 2 varieties, the soft-red winter wheat had a greater bloat potential than the hard-red winter wheat based on results from the cannulated heifers, but no differences were observed in the frequency of bloat in stocker cattle. In this study, shrinking of cattle before grazing wheat pasture did not induce bloat.

Ruminal in situ disappearance kinetics of forages are commonly evaluated in confined animals, but there have been relatively few attempts to evaluate disappearance kinetics of forage dry matter (DM) in grazing animals. Our objectives were 1) to evaluate the effects of harvest technique and sampling date on the in situ DM disappearance kinetics and nutritive value of wheat ( Triticum aestivum L.) forage, and 2) to compare the in situ disappearance kinetics of DM for these forages when the experimental steers were housed in confinement with those obtained from steers grazing wheat pasture. Wheat forage was harvested on three dates (March 6, March 27, and April 11, 2000). Sampling techniques evaluated on each date included three clipping techniques (whole plant, random pluck, and top half) and two evaluations of masticates (oven dried at 50°C or lyophilized). There was an interaction of harvest technique and sampling date main effects for crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), hemicellulose, cellulose, lignin, and whole-plant ash. Disappearance kinetics of DM for these 15 forages were then evaluated by the in situ technique using five 393-±54-kg crossbred steers consuming an alfalfa-based ( Medicago sativa L.) diet in confinement, and subsequently, in five 448±49-kg crossbred steers grazing wheat pasture during March 2001. For fractions A, B, and C, potential extent, rate of disappearance (K d ), and effective ruminal degradability, linear regressions of values obtained for steers grazing wheat pasture on those obtained from confined cattle had significant slopes and exhibited high r 2 statistics (>0.821). For fractions A and B, and K d , the slope of these regression lines did not differ from unity, and the intercept did not differ from zero. For fraction C, potential extent of disappearance, and effective ruminal degradability, slopes were all equal to 1.19 and differed from unity. For effective degradability, deviation of the slope from unity can be explained, in part, on the basis of the passage rates used to calculate these values (0.035 and 0.062/h for confined and grazing steers, respectively). From a practical standpoint, the in situ disappearance kinetics of DM for these wheat forages did not appear to be altered substantially by evaluating them in grazing steers.

Limited information is available that describes the disappearance kinetics of bermudagrass (Cynodon dactylon L. Pers.) during fall and early winter. Five ruminally cannulated, crossbred steers (387 +/- 18.3 kg) were used to determine the effects of calendar date and previous summer management on the in situ degradation kinetics of DM and NDF for forage clipped from stockpiled 'Greenfield' bermudagrass pastures. Forage was stockpiled at two sites following summer hay or pasture management, and samples were taken outside (GRAZED) and under caged exclosures (UNGRAZED) at 4-wk intervals beginning October 17, 1997, and ending January 9, 1998. No effort was made to remove or avoid contaminate species. Concentrations of NDF increased (P0.001) to a maximum for UNGRAZED forages at the hay site between October 17 and December 12, but sampling date had no effect (P = 0.627) on concentrations of NDF at the pasture site. Concentrations of ADF and lignin increased (Por = 0.023) during at least one sampling interval in UNGRAZED forages at both sites. At the hay site, degradation rates of DM decreased (P0.001) by 0.013/h for UNGRAZED forage between October 17 and January 9, whereas the effective ruminal degradability of DM decreased (P0.001) by 33.5% during the same time period. Fractional degradation rates of NDF for UNGRAZED forages at the hay site decreased (P0.001) by 0.014/h between October 17 and November 14 but did not change (Por = 0.077) throughout the remainder of the study. The effective ruminal degradability of NDF decreased (P0.001) by 33.8% between the first and last sampling date. At the pasture site, sampling date did not affect (P = 0.458) rates of DM degradation, but the effective degradability of DM for UNGRAZED forages decreased (P = 0.001) by 19.0% from October 17 to December 12. Rates of NDF degradation for UNGRAZED forages did not differ (Por = 0.113) on the first three sampling dates, but the rate on January 9 was slower than that observed on October 17 (P = 0.025) and November 14 (P = 0.044). The effective degradability of NDF decreased (P0.001) by 19.2% between October 17 and December 12. These data indicate that stockpiled bermudagrass should be used during a limited window during the late fall; after this time, the nutritive value becomes very poor.

Eighty mixed breed steers (avg. wt. 560 lb.) were used to evaluate the effect on grazing gain and subsequent feedlot performance of different management options for steers earlyintensively grazing Acremonium coenophialuminfected tall fescue pastures. Steers were allotted to pastures of infected fescue pastures or infected fescue overseeded with ladino clover and received no supplement or were offered grain sorghum at .25% of their body weight. Neither supplementation nor overseeding affected grazing or feedlot performance. However, grain supplementation on overseeded pastures reduced subsequent feedlot feed efficiency (P

Background Integration of behavioral observations with traditional selection schemes may lead to enhanced animal well-being and more profitable forage-based cattle production systems. Brahman-influenced (BR; n = 64) and Gelbvieh × Angus (GA; n = 64) heifers consumed either toxic endophyte-infected tall fescue (E+) or one of two nontoxic endophyte-infected tall fescue (NT) cultivars during two yr. Heifers were weighed at midpoint and termination of grazing. Grazing behavior (grazing, resting in the shade, lying, or standing without grazing) was recorded (n = 13 visual observations per yr in June and July) for each pasture. During yr 2, exit velocity (EV) and serum prolactin (PRL) were determined. Results Grazing behavior was influenced (P P P P P P Conclusion Collectively fescue cultivar, EV, and concentrations of serum PRL were associated with grazing behavior. Heifers grazing NT pastures were observed to be grazing more than heifers assigned to E+ pastures, regardless of breed type, which may have contributed to changes in BW and average daily gain (ADG) in heifers. Integration of behavioral observations along with traditional selection schemes may lead to enhanced animal well-being and more profitable forage-based cattle production systems.