Replacing toxic, wild-type Neotyphodium coenophialum-infected tall fescue (E+) with nontoxic, N. coenophialum-infected tall fescue (NE+) has improved cow performance, but producer acceptance of NE+ has been slow. The objective was to compare performance by spring- and fall-calving cows grazing either E+ or NE+ at different percentages of the total pasture area. Gelbvieh × Angus crossbred cows (n = 178) were stratified by BW and age within calving season and allocated randomly to 1 of 14 groups representing 5 treatments for a 3-yr study: i) Fall-calving on 100% E+ (F100); ii) Spring-calving on 100% E+ (S100); iii) Fall-calving on 75% E+ and 25% NE+ (F75); iv) Spring-calving on 75% E+ and 25% NE+ (S75); and v) Spring-calving on 100% NE+ (SNE100). Groups allocated to F75 and S75 grazed E+ until approximately 28 d before breeding and weaning, then were then moved to their respective NE+ pasture area for 4 to 6 wk; those allocated to F100, S100, and SNE100 grazed their pastures throughout the entire year. Samples of tall fescue were gathered from specific cells within each pasture at the time cows were moved into that particular cell (∼1 sample/mo). Blood samples were collected from the cows at the start and end of the breeding season. Stocking rate for each treatment was 1 cow/ha. Forage IVDMD, CP, and total ergot alkaloid concentrations were affected (P < 0.05) by the treatment × sampling date interaction. Hay offered, cow BW, and BCS at breeding, end of breeding, and at weaning were greater (P < 0.05) from fall-calving vs. spring-calving. Cow BW at weaning was greater (P < 0.05) from F75 and S75 vs. F100 and S100. The calving season × NE+ % interaction affected (P < 0.05) calving rates. Preweaning calf BW gain, actual and adjusted weaning BW, ADG, sale price, and calf value at weaning were greater (P < 0.05) from fall-calving vs. spring-calving and from SNE100 vs. S75 except for sale price which was greater (P < 0.05) from S75 vs. SNE100. Cow concentrations of serum prolactin at breeding and serum NEFA at the end of breeding were affected (P < 0.05) by the calving season × NE+ % interaction. Serum Zn and Cu concentrations from cows were affected (P < 0.05) by calving season. A fall-calving season may be more desirable for cows grazing E+, resulting in greater calving rates, cow performance, and calf BW at weaning, whereas limited access to NE+ may increase calving rates, serum prolactin, and NEFA concentrations during certain times in the production cycle, particularly in spring-calving cows. Copyright © 2013. American Society of Animal Science .

The potential for acid-detergent insoluble ash (ADIA), alkaline-peroxide lignin (APL), and acid-detergent lignin (ADL) to predict fecal output (FO) and dry matter digestibility (DMD) by cattle offered bermudagrass [Cynodon dactylon (L.) Pers.] hays of different qualities was evaluated. Eight ruminally cannulated cows (594 ± 35.5 kg) were allocated randomly to 4 hay diets: low (L), medium low (ML), medium high (MH), and high (H) crude protein (CP) concentration (79, 111, 131, and 164 g CP/kg on a DM basis, respectively). Diets were offered in 3 periods with 2 diet replicates per period and were rotated across cows between periods. Cows were individually fed 20 g DM/kg of body weight in equal feedings at 08:00 and 16:00 h for a 10-d adaptation followed by a 5-d total fecal collection. Actual DM intake (DMI), DMD, and FO were determined based on hay offered, ort, and feces excreted. These components were then analyzed for ADL, APL, and ADIA concentration to determine marker recovery and marker-based estimates of FO and DMD.

Economically viable options for retaining ownership of spring-born calves through a winter backgrounding program are somewhat limited in the southeastern United States. Although sod-seeded winter annual forages produce less forage than those same forages planted using conventional tillage practices, sod-seeded winter annual forages have the potential to provide a low-cost, rapid-gain, ecologically and economically viable option for retaining ownership of fall-weaned calves. A study was conducted during the winters of 1998, 1999, and 2000 using 180 crossbred calves (261 +/- 2.8 kg initial BW; n = 60 each year) to compare sod-seeded winter annual forages with conventional hay and supplement backgrounding programs in southeast Arkansas. Calves were provided bermudagrass hay (ad libitum) and a grain sorghum-based supplement (2.7 kg/d) on 1-ha dormant bermudagrass pastures or were grazed on 2-ha pastures of bermudagrass/dallisgrass overseeded with 1) annual ryegrass, 2) wheat plus annual ryegrass, or 3) rye plus annual ryegrass at a set stocking rate of 2.5 calves/ha. Calves grazed from mid-December until mid-April but were fed bermudagrass hay during times of low forage mass. Mean CP and IVDMD concentrations were 19.0 and 71.1%, respectively, across sampling dates and winter annual forages, but three-way interactions among forage treatments, year, and sampling date were detected (P < 0.01) for forage mass, concentrations of CP, and IVDMD. The IVDMD of rye plus ryegrass was greater (P < 0.05) than that of ryegrass in yr 2. A forage treatment x sampling date interaction was detected for forage CP in yr 1 (P < 0.05) and 2 (P = 0.05) but not in yr 3 (P = 0.40). Forage mass did not differ (P > or = 0.22) among winter annual treatments on any sampling date. During the first 2 yr, calves fed hay plus supplement gained less (P < 0.05) BW than calves that grazed winter annual forages; gains did not differ (P > or = 0.23) among winter annual treatments. During the 3rd yr, undesirable environmental conditions limited growth of the winter annual forages; total gain did not differ (P = 0.66) among the four treatments. Winter annual forages offer potential to provide high-quality forage for calves retained until spring, but consistent forage production and quality are a concern when sod-seeding techniques are used.

Tarentaise heifers fitted with a rumen cannula (539 +/- 7.5 and 487 +/- 15.7 kg avg initial BW in Exp. 1 and 2, respectively) were used in two Latin square metabolism experiments having 2 x 2 factorial treatment arrangements to determine the effects of supplementation with Aspergillus oryzae fermentation extract (AO) or laidlomycin propionate (LP) on intake, digestion, and digestive characteristics of Neotyphodium coenophialum-infected (IF) or uninfected (FF) tall fescue (Festuca arundinacea) hay diets consumed ad libitum. Heifers were housed in individual stanchions in a metabolism facility with ambient temperatures controlled to range between 26.7 and 32.2 degrees C daily. Total feces and urine were collected for 5 d following a 21-d dietary adaptation period. In situ DM and NDF disappearance and ruminal fermentation characteristics were also determined. In Exp. 1, DMI was 24% greater (P < 0.01) by heifers offered FF than by those offered IF (6.7 vs 5.4 kg/d). Heifers fed 2 g/d AO tended (P = 0.09) to consume 4% more DM than those fed a diet without AO. Degradable DM and NDF fractions of IF were greater (P < 0.01) than those of FF, but AO supplementation did not affect situ disappearance (P > or = 0.42). In Exp. 2, DMI was 18.9% greater (P < 0.01) by heifers offered FF than by those offered IF (6.6 vs 5.5 kg/d). Heifers fed LP (50 mg/d) consumed 10.6% less (P < 0.05) DM than those not fed LP (5.7 vs 6/5 kg/d). Digestibility of NDF tended to be greater (P = 0.08) and digestibility of ADF was greater (P < 0.05) from FF than from IF. Conversely, apparent N absorption (%) was greater (P < 0.05) from IF than from FF. Heifers fed LP had lower (P < 0.05) ADF digestibility than those not fed LP. In situ degradable DM and NDF fractions were greater (P < 0.01) from IF than from FF. Diets supplemented with LP had higher (P < 0.01) indigestible DM and NDF fractions than those without LP. Propionic acid and total VFA concentrations were greater (P < 0.05) from heifers offered FF than from those offered IF and from heifers fed LP than from those not fed LP. Therefore, it appears the major effect of N. coenophialum was a reduction in forage intake and total-tract fiber digestibility in certain situations. Response to the feed additives was similar whether heifers were offered IF or FF and no evidence was apparent that either additive would improve performance substantially by animals consuming low-quality fescue hay diets.

Forage management and environmental conditions affect water soluble carbohydrate (WSC) storage, and, in turn, influence ruminant forage utilization in silvopastoral systems. The objective was to determine effects of four dependent variables: forage species [(non-native, C₃ (orchardgrass (Dactylis glomerata L.)) and native C₄ mix (8:1:1 big bluestem (Andropogon gerardii Vitman), little bluestem (Schizachyrium scoparium Michx. Nash) and indiangrass (Sorghastrum nutans L.))]; fertility (poultry litter and an unfertilized control); forage sampling date (mid-May, late-May, early-June, mid-June, and late-June); and hour of day (0800, 1100, 1400, and 1700 h) on WSC accumulation in a silvopasture. Concentrations of WSC (g kg DM⁻¹) were greater (p ≤ 0.05) for C₃ forages, with poultry litter not impacting WSC accumulation. Overall, WSC was greatest in mid-June, with the lowest WSC concentration observed at 0800 compared to 1100, 1400, and 1700 h (p ≤ 0.05). Therefore, harvesting forages later in the day resulted in greater WSC. A stepwise regression model indicated acid detergent fiber, ash, and forage P concentration were the best predictors (R₂ = 0.85, p ≤ 0.05) of forage WSC. These results may be useful in future studies aimed at explaining diurnal cattle grazing preference and optimum forage harvest timing in silvopastoral systems.