A.N. Young

Performance by spring and fall-calving cows grazing with full, limited, or no access to toxic Neotyphodium coenophialum-infected tall fescue1

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.

Storage characteristics, nutritive value, energy content, and in vivo digestibility of moist, large rectangular bales of alfalfa-orchardgrass hay treated with a propionic acid-based preservative1

Unstable weather, poor drying conditions, and unpredictable rainfall events often place valuable hay crops at risk. Recent research with large round bales composed of alfalfa (Medicago sativa L.) and orchardgrass (Dactylis glomerata L.) has shown that these large-bale packages are particularly sensitive to spontaneous heating and dry matter (DM) losses, as well as other undesirable changes with respect to forage fiber, protein, and energy density. Various formulations of organic acids have been marketed as preservatives, normally for use on hays that are not desiccated adequately in the field to facilitate safe bale storage. Our objectives for this study were to (1) evaluate the efficacy of applying a commercial (buffered) propionic acid-based preservative at 3 rates (0, 0.6, and 1.0% of wet-bale weight) to hays baled at 3 moisture concentrations (19.6, 23.8, and 27.4%) on the subsequent storage characteristics and poststorage nutritive value of alfalfa-orchardgrass forages packaged in large rectangular (285-kg) bales, and then (2) evaluate the in vivo digestibility of these hays in growing lambs. Over a 73-d storage period, the preservative was effective at limiting spontaneous heating in these hays, and a clear effect of application rate was observed for the wettest (27.4%) bales. For drier hays, both acid-application rates (1.0 and 0.6%) yielded comparable reductions in heating degree days >30°C relative to untreated controls. Reductions in spontaneous heating could not be associated with improved recovery of forage DM after storage. In this study, most changes in nutritive value during storage were related to measures of spontaneous heating in simple linear regression relationships; this suggests that the modest advantages in nutritive value resulting from acid treatment were largely associated with perturbations of normal heating patterns during bale storage. Although somewhat erratic, apparent digestibilities of both DM (Y=-0.0080x + 55.6; R(2)=0.45) and organic matter (Y=-0.0085x + 55.5; R(2)=0.53) evaluated in growing lambs were also directly related to heating degree days in simple linear relationships. Based on these data, applying propionic acid-based preservatives to large rectangular bales is likely to provide good insurance against spontaneous heating during storage, as well as modest benefits with respect to nutritive value and digestibility.

Cooked color of precooked ground beef patties manufactured with mature bull trimmings

Lean (80%) ground beef was formulated with 0, 25, 50, 75, or 100% mature bull trimmings, formed into patties, cooked to 71 °C in an air-impingement oven, and stored at -20 °C until reheating to 71 °C either in a microwave oven or on a gas-fired chargrill. Instrumental color of raw patties was not (P ≥ .080) affected by levels of bull trim. After initial cooking, internal cooked redness values were not affected (P ≥ .202) by the proportion of bull trim; however, the internal reheated patty redness increased (greater a* values and lesser HA; P ≤ .001) with increasing proportions of bull trimmings. Formulating ground beef with high levels (>50%) of mature, bull trimmings had minimal effects on raw ground beef color, but patties formulated with the highest proportions of bull trimmings appeared undercooked even after cooking twice to 71 °C.

Nutritive value and in situ digestibility of pearl millet hay as affected by moisture concentration and bale sampling depth

Seven hectares (ha) of pearl millet [Pennisetum glaucum (L.) R. Br.] were divided into 3 blocks with 3 whole plots each to evaluate the effects of moisture (165, 187, and 274 g/kg of DM) and sampling depth (0.2, 0.4, and 0.6 m) in round bales on chemical composition and in situ disappearance. Plots were assigned randomly to moisture treatments. Round bales (n = 3 per plot; 1.2 × 1.5 m, 568 kg) were obtained and sampled at 3 different depths within each bale (n = 81) before and after 71 d of storage. Duplicate in situ bags (10 × 20 cm) were incubated in 6 ruminally cannulated cows (BW = 585 ± 37.8 kg) up to 120 h. Residual DM for each sampling time was fit to a nonlinear model using PROC NLIN of SAS to determine DM degradation kinetics. Data were analyzed as a split-plot design using Proc Mixed procedures of SAS and tested for moisture, depth, and their interactions. Bale temperature and concentrations of ADL were greater (P 0.10) any of the digestion variables, but the water-soluble fraction, potentially degradable fraction, and effective ruminal disappearance as well as concentrations of OM, NDF, and acid-detergent insoluble nitrogen were affected (P < 0.05) by the moisture × sampling depth interaction. Therefore, a greater range in sampling depth should be used to accurately assess heat damage in large round bales.