Comparison of two in situ reference methods to estimate indigestible NDF by near infrared reflectance spectroscopy in alfalfa.

Undigested forage neutral detergent fiber (uNDF) from long-term ruminal in situ incubations are used to estimate indigestible neutral detergent fiber (iNDF). Measurement of iNDF is important in forage evaluation because it defines the potentially digestible pool of neutral detergent fiber (NDF). Near-infrared reflectance spectroscopy (NIRS) can be calibrated to in situ reference sets to rapidly predict uNDF. Our objective was to compare uNDF estimates after 240 h of incubation when two types of bags were used in the in situ reference method. The bags compared were 4 cm × 5 cm Ankom F57 bags (25 micron pore size), and 5 cm × 10 cm Ankom in situ bags (50 micron pore size). Alfalfa samples from Pennsylvania and Wisconsin (n = 144) of different varieties and harvest intervals were used. One-half or two gram samples, respectively, were weighed into the small and large bags in triplicate. Mass to surface area was 0.05 and 0.02 g/cm2 for the small and large bags, respectively. The iNDF content after 240 h incubation was evaluated by two types bags in three rumen-cannulated Holstein cows. Each dried and ground forage was also scanned to determine the visible-near-infrared-reflectance spectra with a FOSS 6500 spectrophotometer. Prediction equations were developed for each bag type using modified partial least square regressions. The estimated iNDF fraction from small and large bags were 13.75% and 9.97%, respectively (SED = 0.39, P < 0.001). The coefficient of determination for calibration (R2), cross-validation (1 - VR), calibration standard deviation (SEC), and interactive authentication standard deviation (SECV) was 0.94, 0.92, 0.85 and 0.98 for values determined with the small bag and 0.88, 0.85, 1.12 and 1.27 for iNDF for values determined with the large bag, respectively. Results indicate that iNDF varies among alfalfa cultivars and NIRS can be used to quickly and quantitatively estimate iNDF content in alfalfa. Bag type influences 240h NDF residues. NIRS predictions of iNDF from the small bag calibration set had higher R2 and lower SEC and SECV than the large bag calibrations.

Randomized clinical trial to assess the effect of antibiotic therapy on health and growth of preweaned dairy calves diagnosed with respiratory disease using respiratory scoring and lung ultrasound.

The primary objective of this randomized field study was to assess the effect of antibiotic therapy on health and growth of preweaned dairy calves diagnosed with naturally occurring respiratory disease, using respiratory scoring and portable lung ultrasound. A secondary objective was to determine whether treatment response depended on clinical presentation at the time of diagnosis. Holstein calves (n = 357) were enrolled at 3 to 6 d of age and followed until 52 d on 2 commercial dairies. Calves were examined twice weekly by blinded members of the research team. Clinical respiratory and ultrasonographic lung scores were assigned at each exam and used to classify the first detected respiratory disease event (BRD1) into upper respiratory tract disease (clinical, no significant consolidation); subclinical lobular pneumonia (not clinical, patchy consolidation ≥1 cm2); clinical lobular pneumonia (clinical, patchy consolidation ≥1 cm2); subclinical lobar pneumonia (not clinical, ≥1 lobe consolidated); and clinical lobar pneumonia (clinical, ≥1 lobe consolidated). At BRD1, calves were blocked by their respiratory disease status and randomized to receive an antibiotic (tulathromycin, 2.5 mg/kg subcutaneous) or placebo (sterile saline, equal volume subcutaneous). Multivariable linear and logistic regression analyses were used to model response to therapy. At BRD1 (n = 289), the distribution of diagnoses was 29% (upper respiratory tract disease), 43% (subclinical lobular pneumonia), 13% (clinical lobular pneumonia), 8% (subclinical lobar pneumonia), and 7% (clinical lobar pneumonia). Early antibiotic therapy limited progression of lung consolidation immediately following treatment, reduced the likelihood of requiring treatment within 7 d of BRD1, and improved growth and mortality before weaning. Despite receiving multiple doses of antibiotics after BRD1, calves treated with either antibiotic or placebo were equally likely to enter the weaning phase with pneumonia. Clinical presentation was associated with response to treatment for worsening of consolidation, early treatment failure, days to retreatment, and average daily gain. Overall, treatment was associated with short-term benefits, but more research is needed to develop treatment protocols that more effectively treat pneumonia and ensure that calves enter the weaning period with ultrasonographically clean lungs.

Technical note: Comparison of dry matter measurements from handheld near-infrared units with oven drying at 60°C for 48 hours and other on-farm methods.

This study compared dry matter (DM) predictions of 3 handheld near-infrared spectrophotometer (NIRS) units (Moisture Tracker, Digi-Star Inc., Fort Atkinson, WI) to conventional oven drying at 60°C using 2 alfalfa and 2 corn silages. In addition, on-farm DM methods [microwave, Koster tester (Koster Moisture Tester Inc., Brunswick, OH), and food dehydrator methods] were also compared. Corn and alfalfa silages (1,600 g) obtained from the University of Wisconsin Dairy Cattle Center (DCC) and the Arlington Research Station (ARS) were analyzed for DM daily for 20 d. Two NIRS calibration methods were also tested within each unit. The DM predicted from the factory-preset calibrations was NIRf. The adjusted DM prediction was NIRa, where the average difference between oven-dried and NIRf determined on duplicate forage samples for 3 d before the experiment was used as a bias adjustment for all subsequent DM determinations. The average predicted DM from the 20 scans was recorded as the forage DM. The process was repeated 3 times with each NIRS unit. Two 100-g subsamples of each forage were also oven-dried for 48 h at 60°C daily in a forced-air oven. Oven DM of ARS and DCC alfalfa silages were 37.3 ± 1.1% and 48.5 ± 1.9%, respectively (mean ± standard deviation). Oven DM of ARS and DCC corn silages were 34.7 ± 1.2% and 37.4 ± 0.5%, respectively (mean ± standard deviation). Dry matter determinations from NIRf were on average 3.5 units higher than the oven DM values. The NIRa DM predictions were on average 1.7 DM units lower than the oven DM values. Additionally, differences among the 3 NIRf probe results were detected (43.1, 40.7, and 41.3% DM, respectively), but all other results were similar between probes. Determinations of DM by the microwave and food dehydrator were also similar with the 60°C, 48-h oven method, whereas the Koster tester was lower than the oven. The handheld NIRS units more accurately predicted DM content of the alfalfa silage but were not as accurate with corn silages when the factory preset calibrations were corrected for bias.

Technical note: A comparison of alkali treatment methods to improve neutral detergent fiber digestibility of corn stover.

The objective of this study was to compare neutral detergent fiber (NDF) digestibility of corn stover that had been treated by 2 alkali treatment methods. Two experiments were conducted to test a sodium hydroxide (NaOH) treatment method that uses an ethanol/water co-solvent (NaOH/ethanol-H2O, United States Patent No. 20140220228) and a calcium hydroxide (CaOH) treatment method, which uses water as a solvent (CaOH/H2O). An in situ trial was conducted to compare NDF digestion kinetics between NaOH/ethanol-H2O-treated stover, CaOH/H2O-treated stover, untreated corn stover, and soy hulls. The digestion rate of potentially digestible NDF (kd) of NaOH/ethanol-H2O-treated corn stover (5.36%/h) was higher than CaOH/H2O-treated stover (2.27%/h), or untreated corn stover (1.76%/h) and similar to the kd of soy hulls (4.93%/h). The indigestible NDF (iNDF) fraction of untreated corn stover (35.1% of NDF) was reduced by CaOH/H2O treatment (27.3% of NDF) and by NaOH/ethanol-H2O treatment (2.8% of NDF). The iNDF fraction in soy hulls (3.6% of NDF) was similar to iNDF of NaOH/ethanol-H2O-treated stover. An in vivo digestibility trial was also conducted to compare fiber digestibility of diets supplemented with untreated corn stover, NaOH/ethanol-H2O-treated corn stover, or soy hulls. Total-tract apparent dry matter (DM) and NDF digestibility were measured with 8 lactating Holstein cows in a replicated 4 × 4 Latin square with four 21-d periods. Apparent DM digestibility (DMD) was improved when supplemental soy hulls were added to the base diet (60.0% DMD) compared with the base diet with no supplemental fiber (57.7% DMD). Apparent DM digestibility was reduced when diets were supplemented with untreated stover (52.4%). Dry matter digestibility of NaOH/ethanol-H2O-treated stover was similar (54.8% DMD) to all other treatments. Digestibility of NDF was lowest when cows were fed the diet with supplemented untreated stover (35.5% of NDF), and improved when soy hulls (40.6% of NDF) or NaOH/ethanol-H2O-treated stover (43.8% of NDF) were added to the diets. The NaOH/ethanol-H2O treatment process improves the DM and NDF digestibility of corn stover to values similar to those of soy hulls.

The effects on digestibility and ruminal measures of chemically treated corn stover as a partial replacement for grain in dairy diets.

Alkaline treatment of gramineous crop residues can convert an abundant, minimally utilized, poorly digestible straw into a moderately digestible feedstuff. Given the volatile nature of grain prices, substitution of treated stover for grain was investigated with dairy cows to provide insights on ruminal and digestibility effects of a feed option that makes use of alternative, available resources. The objective of this study was to evaluate changes in diet digestibility and ruminal effects when increasing levels of calcium oxide-treated corn stover (CaOSt) were substituted for corn grain in diets of lactating cows. Mature corn stover was treated with calcium oxide at a level of 50g∙kg(-1) dry matter (DM), brought up to a moisture content of 50% following bale grinding, and stored anaerobically at ambient temperatures for greater than 60d before the feeding experiment. Eight ruminally cannulated Holstein cows averaging 686kg of body weight and 35kg of milk∙d(-1) were enrolled in a replicated 4×4 Latin square, where CaOSt replaced corn grain on a DM basis in the ration at rates of 0, 40, 80, and 120g∙kg(-1) DM. All reported significant responses were linear. The DM intake declined by approximately 1kg per 4% increase in CaOSt inclusion. With increasing replacement of corn grain, dietary neutral detergent fiber (NDF) concentration increased. However, rumen NDF turnover, NDF digestibility, NDF passage rate, and digestion rate of potentially digestible NDF were unaffected by increasing CaOSt inclusion. Total-tract organic matter digestibility declined by 5 percentage units over the range of treatments, approximately 1.5 units per 4-percentage-unit substitution of CaOSt for grain. With increasing CaOSt, the molar proportions of butyrate and valerate declined, whereas the lowest detected ruminal pH increased from 5.83 to 5.94. Milk, fat, and protein yields declined as CaOSt increased and DM intake declined with the result that net energy in milk declined by approximately 1 Mcal per 4% increase in CaOSt. Time spent ruminating (min∙kg(-1) DM intake) increased with increasing CaOSt, though total minutes per day were unaffected. These insights on the effect of substitution of treated corn stover for corn grain may be used to predict the effect on nutrient supply to the cow over a range of substitution levels. The acceptability of the effect will depend on the economics of milk production and availabilities of feedstuffs.

Effects of partial replacement of corn and alfalfa silage with tall fescue hay on total-tract digestibility and lactation performance in dairy cows.

Our objective was to evaluate the effects of replacing either corn or alfalfa silage with tall fescue hay on total-tract neutral detergent fiber (NDF) digestibility and lactation performance in dairy cows. Twenty-four primiparous (75±35 d in milk) and 40 multiparous (68±19 d in milk) Holstein cows were blocked by parity and randomly assigned to 1 of 4 treatment groups in a pen equipped with 32 feeding gates to record intake by cow. Each gate was randomly assigned to 1 treatment group; thus, each cow had access to all 8 gates within the respective treatment and cow was the experimental unit. Treatments were formulated to replace either corn silage (CS) or alfalfa silage (AS) with tall fescue hay (TF) as follows (DM basis): 33% AS and 67% CS (control; 33AS67CS), 60% TF and 40% AS (60TF40AS), 60% TF and 40% CS (60TF40CS), and 33% TF and 67% CS (33TF67CS). The experiment was a 7-wk continuous lactation trial with a 2-wk covariate period. Milk production did not differ among treatments and averaged 40.4 kg/d. Fat yield and concentration and protein yield and concentration did not differ among treatments and averaged 1.58 kg/d, 3.94%, 1.28 kg/d, and 3.15%, respectively. Dry matter intake was greater for 33AS67CS (24.5 kg/d) compared with 60TF40CS (22.1 kg/d) and 33TF67CS (22.7 kg/d), and tended to be greater than 60TF40AS (23.2 kg/d). In vivo total-tract dry matter digestibility did not differ among treatments and averaged 66.2%. In vivo total-tract NDF digestibility was lower for 33AS67CS (37.8%) compared with 60TF40AS (44.4%) and 33TF67CS (45.3%), and similar to 60TF40CS (42.4%). In vivo total-tract NDF digestibility and an estimate of in situ total-tract NDF digestibility were similar between techniques across all treatment diets (42.3 vs. 42.6%, respectively). Inclusion of tall fescue grass hay increased the total-tract NDF digestibility of the diet and has the potential to replace corn silage and alfalfa silage and maintain milk production if economically feasible based on current market prices.

The effects of calcium hydroxide-treated whole-plant and fractionated corn silage on intake, digestion, and lactation performance in dairy cows.

The objective of this trial was to evaluate, in dairy cattle, the effects of calcium hydroxide treatment of whole-plant corn and a treatment applied to the bottom stalk fraction of the corn plant, achieved by harvesting corn in 2 crop streams. The treatments were calcium hydroxide-treated corn silage (TRTCS), toplage supplemented with calcium hydroxide-treated stalklage (TPL), a positive control of brown midrib corn silage (BMR), and a negative control of conventional whole-plant corn silage (WPCS). The toplage was harvested at a height of 82 cm with 2 of the 6 rows set as ear-snapping to incorporate higher tissues into the stalklage. Stalklage was harvested at 12 cm, and other corn silages were harvested at 27 cm. Sixteen pens, each with 8 Holstein cows averaging 70±25 d in milk and 46±11 kg of milk d(-1), were assigned 4 per treatment in a completely randomized design. The diet was approximately 40% corn silage, 20% alfalfa silage, and 40% concentrate on a dry matter basis. A 2-wk covariate period with conventional corn silage was followed by an 8-wk treatment period in which the 4 corn silage treatments were the only effective difference in diets. Cows fed TPL and TRTCS consumed more (1.9 and 1.4 kg of organic matter d(-1), respectively) than did cows fed WPCS. Milk yield was greater for cows fed BMR, TPL, and TRTCS. Cows fed BMR and TPL produced 2.9 and 2.7 kg d(-1), respectively, more energy-corrected milk (ECM) than cows fed WPCS, and cows fed TRTCS had the greatest ECM production (4.8 kg of ECM d(-1) greater than cows fed WPCS). No differences in body weight or body condition scored were observed. Milk fat concentration was similar among treatments and milk protein concentration was reduced for TRTCS. Starch and neutral detergent fiber digestibility were greater for cows fed TRTCS.

Comparison of in situ versus in vitro methods of fiber digestion at 120 and 288 hours to quantify the indigestible neutral detergent fiber fraction of corn silage samples.

Ruminal digestion of neutral detergent fiber (NDF) is affected in part by the proportion of NDF that is indigestible (iNDF), and the rate at which the potentially digestible NDF (pdNDF) is digested. Indigestible NDF in forages is commonly determined as the NDF residue remaining after long-term in situ or in vitro incubations. Rate of pdNDF digestion can be determined by measuring the degradation of NDF in ruminal in vitro or in situ incubations at multiple time points, and fitting the change in residual pdNDF by time with log-transformed linear first order or nonlinear mathematical treatments. The estimate of indigestible fiber is important because it sets the pool size of potentially digestible fiber, which in turn affects the estimate of the proportion of potentially digestible fiber remaining in the time series analysis. Our objective was to compare estimates of iNDF based on in vitro (IV) and in situ (IS) measurements at 2 fermentation end points (120 and 288h). Further objectives were to compare the subsequent rate, lag, and estimated total-tract NDF digestibility (TTNDFD) when iNDF from each method was used with a 7 time point in vitro incubation of NDF to model fiber digestion. Thirteen corn silage samples were dried and ground through a 1-mm screen in a Wiley mill. A 2×2 factorial trial was conducted to determine the effect of time of incubation and method of iNDF analysis on iNDF concentration; the 2 factors were method of iNDF analysis (IS vs. IV) and incubation time (120 vs. 288h). Four sample replicates were used, and approximately 0.5g/sample was weighed into each Ankom F 0285 bag (Ankom Technology, Macedon, NY; pore size=25 µm) for all techniques. The IV-120 had a higher estimate of iNDF (37.8% of NDF) than IS-120 (32.1% of NDF), IV-288 (31.2% of NDF), or IS-288 technique (25.7% of NDF). Each of the estimates of iNDF was then used to calculate the rate of degradation of pdNDF from a 7 time point in vitro incubation. When the IV-120 NDF residue was used, the subsequent rates of pdNDF digestion were fastest (2.8% h(-1)) but the estimate of lag was longest (10.3h), compared with when iNDF was based on the IS-120 or IV-288 NDF residues (rates of 2.3%h(-1) and 2.4%h(-1); lag times of 9.7 and 9.8 h, respectively). Rate of pdNDF degradation was slowest (2.1% h(-1)) when IS-288 NDF residue was used as the estimate of iNDF. The estimate of lag based on IS-288 (9.4h) was similar to lag estimates calculated when IS-120 or IV-288 were used as the estimate of iNDF. The TTNDFD estimates did not differ between treatments (35.5%), however, because differences in estimated pools of iNDF resulted in subsequent changes in rates and lag times of fiber digestion that tended to cancel out. Estimates of fiber digestion kinetic parameters and TTNDFD were similar when fit to either the linear or nonlinear fiber degradation models. All techniques also yielded estimates of iNDF that were higher than predicted iNDF based on the commonly used ratio of 2.4 × lignin.

Effects of varying dietary ratios of corn silage to alfalfa silage on digestion of neutral detergent fiber in lactating dairy cows.

An in vivo study was performed to test an in vitro procedure and model that predicts total-tract neutral detergent fiber (NDF) digestibility for lactating dairy cattle. Corn silage (CS) and alfalfa silage (AS) were used as forages for this study. These forages had similar NDF composition, but fiber in the CS contained less indigestible NDF compared with AS (35.5 and 47.8% of indigestible NDF, respectively). The in vitro method estimated rate of digestion of alfalfa potentially digestible NDF to be approximately 2 times faster than CS fiber (6.11 and 3.21%/h, respectively). Four diets were formulated containing different proportions of CS to AS: 100CS:0AS, 67CS:33AS, 33CS:67AS, and 0CS:100AS, as percentage of diet DM basis. The objective was to construct diets that contained approximately similar levels of NDF but with different pool sizes and rates of digestion of potentially digestible NDF. Diets were fed to 8 ruminally cannulated, multiparous, lactating dairy cows in a replicated 4×4 Latin square with 21-d periods. Total-tract fiber digestibility and fiber digestion kinetic parameters observed in vivo were compared with the values predicted by the in vitro assay and model. Total-tract NDF digestibility coefficients were similar (41.8 and 40.6% of total NDF) for the in vitro and in vivo methods, respectively. As the proportion of dietary alfalfa increased, the digestibility of NDF increased. The rate of digestion of potentially digestible NDF predicted from the in vitro assay was also similar to what was observed in vivo. Results suggest that the in vitro total-tract NDF digestibility model could be used to predict rate of fiber digestion and NDF digestibility for lactating dairy cattle.

Validation of an approach to predict total-tract fiber digestibility using a standardized in vitro technique for different diets fed to high-producing dairy cows.

The experimental objective was to validate an in vitro model to predict total-tract neutral detergent fiber (NDF) digestibility in dairy cattle. Twenty-one diets from 7 studies conducted at University of Wisconsin-Madison were analyzed for in vitro fiber digestibility. Forages varied among diets (corn, alfalfa, tall and meadow fescue, and wheat straw silages) and nutrient composition (ranges: NDF = 22.5 to 33.8%; crude protein = 15.8 to 18.9%; nonfiber carbohydrates = 38.0 to 51.0%). Total-tract NDF digestibility (TTNDFD) observed in in vivo trials was determined using different markers as described in the individual studies. The in vitro TTNDFD model predicted total-tract fiber digestibility from the proportion of total NDF potentially digestible (pdNDF), rate of pdNDF degradation, and rate of passage of pdNDF. The model predicted TTNDFD similar to in vivo measurements. The relationship between TTNDFD measured in vivo and TTNDFD predicted by the in vitro assay was significant (R(2) = 0.68). The relationship between in vitro 30-h NDF digestibility values and in vivo total-tract NDF digestibility values was not significant, whereas in vitro 48-h NDF digestibility values were correlated (R(2) = 0.30) with in vivo TTNDFD measurements. Indigestible NDF (iNDF) showed a negative relationship (R(2) = 0.40) with TTNDFD in vivo. Each 1-percentage-unit increase of iNDF resulted in a decrease of 0.96 percentage units of total-tract NDF digestibility; however, iNDF by itself was not a good predictor of TTNDFD because of the difference among the means. This study showed that an in vitro TTNDFD model that uses iNDF, pdNDF, and rates of pdNDF digestion and passage can predict (R(2) = 0.68) total-tract NDF digestibility. Most importantly, we demonstrated the ability to predict total-tract fiber digestibility from a model based on in vitro NDF degradation, which could improve our ability to optimize forage utilization and milk production.

Validation of an in vitro model for predicting rumen and total-tract fiber digestibility in dairy cows fed corn silages with different in vitro neutral detergent fiber digestibilities at 2 levels of dry matter intake.

An in vivo study was performed to validate an in vitro procedure that predicts rate of fiber digestion and total-tract neutral detergent fiber digestibility (TTNDFD). Two corn silages that differed in fiber digestibility were used in this trial. The corn silage with lower fiber digestibility (LFDCS) had the TTNDFD prediction of 36.0% of total NDF, whereas TTNDFD for the corn silage with higher fiber digestibility (HFDCS) was 44.9% of total neutral detergent fiber (NDF). Two diets (1 with LFDCS and 1 with HFDCS) were formulated and analyzed using the in vitro assay to predict the TTNDFD and rumen potentially digestible NDF (pdNDF) digestion rate. Similar diets were fed to 8 ruminally cannulated, multiparous, high-producing dairy cows in 2 replicated 4×4 Latin squares with 21-d periods. A 2×2 factorial arrangement of treatments was used with main effects of intake (restricted to approximately 90% of ad libitum intake vs. ad libitum) and corn silage of different fiber digestibility. Treatments were restricted and ad libitum LFDCS as well as restricted and ad libitum HFDCS. The input and output values predicted from the in vitro model were compared with in vivo measurements. The pdNDF intake predicted by the in vitro model was similar to pdNDF intake observed in vivo. Also, the pdNDF digestion rate predicted in vitro was similar to what was observed in vivo. The in vitro method predicted TTNDFD of 50.2% for HFDCS and 42.9% for LFDCS as a percentage of total NDF in the diets, whereas the in vivo measurements of TTNDFD averaged 50.3 and 48.6% of total NDF for the HFDCS and LFDCS diets, respectively. The in vitro TTNDFD assay predicted total-tract NDF digestibility of HFDCS diets similar to the digestibility observed in vivo, but for LFDCS diets the assay underestimated the digestibility compared with in vivo. When the in vitro and in vivo measurements were compared without intake effect (ad libitum and restricted) considering only diet effect of silage fiber digestibility (HFDCS and LFDCS), no differences were observed between methods. These values suggest that our in vitro TTNDFD model could be used to predicted rate of fiber digestion and NDF digestibility for dairy cattle.

Introductory animal science-based instruction influences attitudes on animal agriculture issues.

The demographics of incoming university animal science majors have shifted from students with a farm background to urban students with no history of direct livestock contact. Research completed before the Internet was a central source of information indicated that incoming urban students tend to express no opinion or a neutral opinion regarding livestock agriculture issues. Due to the changing background of incoming students enrolled in introductory university-level animal science classes, we sought to determine 1) if livestock background (self-identified as raised in a farm or urban setting), sex, or animal science career interest influenced the opinions of incoming students regarding critical issues involving livestock farming practices and 2) if 15 wk of introductory animal science instruction changed student opinions. A total of 224 students were given 2 identical anonymous surveys (start and end of 15 wk) with 5 demographic questions and 9 animal issue statements. For each statement, students marked their opinion by placing a vertical line on a continuous 130 mm horizontal line, where a vertical line placed at 0 mm = strongly agree and 130 mm = strongly disagree. Data were analyzed by ANOVA to determine any significant effects of instruction, background, sex, and future career preference on survey responses. Before instruction, urban students were less agreeable than farm students that animal farming was moral and humane and that farmers are concerned about animal welfare and livestock are of value to society (P ≤ 0.05). Urban students were more likely than farm students to purchase organic foods or food based on environmental/welfare standards (P ≤ 0.05). Introductory animal science instruction resulted in students becoming more agreeable that animal farming was humane, farmers are concerned about animal welfare, and animal agriculture is a value to society (P ≤ 0.05). Postinstruction, students were more likely to buy food products based on price (P ≤ 0.05). Males found farm practices more humane than females (P ≤ 0.05), but sex differences were not evident for other questions. Future professional career plans did not affect student opinions. Data showed that incoming urban students tend to be more neutral with regards to animal farming issues, and introductory animal science instruction fosters a more agreeable attitude towards animal farming practices, especially in students with urban backgrounds.

Effects of acute feed restriction combined with targeted use of increasing luteinizing hormone content of follicle-stimulating hormone preparations on ovarian superstimulation, fertilization, and embryo quality in lactating dairy cows.

Multiple metabolic and hormonal factors can affect the success of protocols for ovarian superstimulation. In this study, the effect of acute feed restriction and increased LH content in the superstimulatory FSH preparation on numbers of ovulations, fertilization, and embryo quality in lactating dairy cows was evaluated. Two experiments were performed using a Latin square design with treatments arranged as a 2 × 2 factorial: feed restriction (FR; 25% reduction in dry matter intake) compared with ad libitum (AL) feeding, combined with high (H) versus low (L) LH in the last 4 injections of the superstimulatory protocol. As expected, FR decreased circulating insulin concentrations (26.7 vs. 46.0 µU/mL). Two analyses were performed: one that evaluated the complete Latin square in experiment 2 and a second that evaluated only the first periods of experiments 1 and 2. For both analyses, follicle numbers, ovulation rates, and corpora lutea on d 7 were not different. In the first period analysis of experiments 1 and 2, we observed an interaction between feed allowance and amount of LH on fertilization rates, percentage of embryos or oocytes that were quality 1 and 2 embryos, and number of embryos or oocytes that were degenerate. Fertilization rates were greater for the AL-L (89.4%) and FR-H (80.1%) treatments compared with the AL-H (47.9%) and FR-L (59.9%) treatments. Similarly, the proportion of total embryos or oocytes designated as quality 1 and 2 embryos was greater for AL-L (76.7%) and FR-H (73.4%) treatments compared with AL-H (35.6%) and FR-L (47.3%) treatments. In addition, the number of degenerate embryos was decreased for AL-L (1.3) and FR-H (0.4) treatments compared with the AL-H (2.6) and FR-L (2.3) treatments. Thus, cows with either too low (FR-L) or too high (AL-H) insulin and LH stimulation had lesser embryo production after superstimulation because of reduced fertilization rate and increased percentage of degenerate embryos. Therefore, interaction of the gonadotropin content of the superstimulatory preparation with the nutritional program of the donor cow needs to be considered to optimize success of ovarian superstimulatory protocols.

Assessment of heifer grazing experience on short-term adaptation to pasture and performance as lactating cows.

A 3-yr study evaluated the carryover effects of dairy heifer grazing experience on behavior and first-lactation performance as dairy cows. Forty-one Holstein and 23 Holstein-Jersey crossbred calves born between January and April 2008 were randomly assigned to 1 of 4 treatments (n=8 per group, 2 groups per treatment) in a completely randomized design. Treatments were combinations of managing dairy heifers in confinement (CNF) or on pasture (PST): grazed yr 1 and 2 (PSTPST); grazed yr 1, but confined yr 2 (PSTCNF); confined yr 1 and grazed yr 2 (CNFPST); or confined yr 1 and 2 (CNFCNF). After calving, all heifers on all treatments were grazed as cows in yr 3. In yr 1, PSTPST and PSTCNF heifers were grazed for 41 d on Italian ryegrass pastures, whereas CNFPST and CNFCNF were housed in bedded-pack pens and fed a TMR. In yr 2, PSTPST and CNFPST heifers grazed Italian ryegrass pasture for 65 d, whereas PSTCNF and CNFCNF remained in confinement. In yr 2, a mid-trial assessment of heifer grazing behavior was made on PSTPST versus CNFPST heifers. Grazing activities were assessed by visual observation and heifer movement measured by portable global positioning system units. Heifers from all treatment groups subsequently calved between January and April in yr 3. All primiparous cows were then allocated to pastures by treatment group, grazed for 61 d, (May through July) in yr 3, with grazing behavior and milk production evaluated while grazing. In yr 2, heifers on the PSTPST treatment spent more time grazing than heifers on the CNFPST treatment (78 vs. 35% of the time) when first exposed to pasture (d 1). On d 1 to 3, PSTPST heifers walked a greater distance than CNFPST heifers; however, PSTPST and CNFPST heifers had similar daily grazing times and walking patterns after 3 d of pasture exposure in yr 2. As lactating cows (yr 3), cows with no (CNFCNF) grazing experience grazed less on d 1 compared with cows with (PSTPST, PSTCNF, or CNFPST) grazing experience. Day-1 grazing times in yr 3 were 62, 59, 76, and 13% of the times for cows with PSTPST, PSTCNF, CNFPST, and CNFCNF grazing experience, respectively. In yr 3, on d 1 to 3, cows with previous grazing experience as heifers (PSTPST, CNFPST, and PSTCNF) walked a greater distance than cows without previous grazing experience (CNFCNF). Milk production was lowest on d 1 to 3 for cows with no previous grazing experience (CNFCNF), but average daily milk production was not different overall over the 61 d of study in yr 3. Results indicate that grazing experiences as a heifer can affect behavior and milk production during a cow's first days on pasture. After a short acclimation period, dairy cows without grazing experience as heifers developed similar grazing behaviors and performance as cows with grazing experience as heifers.

Effect of Lactobacillus inoculants and forage dry matter on the fermentation and aerobic stability of ensiled mixed-crop tall fescue and meadow fescue.

This study evaluated the effects of Lactobacillus plantarum with or without Lactobacillus buchneri on the fermentation and aerobic stability of mixed tall fescue (Festuca arundinacea Schreb) and meadow fescue (Festuca pratensis Huds.) silage ensiled at different dry matter (DM) contents. The first cut was harvested at boot stage and second-cut grasses were harvested when 30- to 35-cm tall. Four DM content treatments of the first cut were 17.9, 24.9, 34.6, and 48.7%; and of the second cut were 29.1, 36.3, 44.1, and 49.2%. Chopped grasses at each DM content were treated with (1) deionized water (control), (2) Lb. plantarum MTD-1 (LP), or (3) a combination of Lb. plantarum MTD-1 and Lb. buchneri 40788 (LP+LB). The application amount of each inoculant to the fresh forage was 1 × 10(6) cfu/g. Grasses were ensiled in vacuum-sealed polyethylene bags containing 150 g of DM for 60 d, with 4 replicates for each treatment. Silages inoculated with LP+LB had greater pH compared with untreated or LP-treated silages. Lactate was greater in LP silage than control or LP+LB silages. As silage DM increased, lactate in untreated and LP-treated silages decreased, but increased in LP+LB-treated silage. Acetate concentration decreased with increased DM in all silages. The LP+LB-treated silage had the longest and control silage the shortest aerobic stability for both harvests. The greatest values in aerobic stability were observed in silages with highest DM content. In this study, aerobic stability of grass mixes ensiled between 18 and 44% DM content increased as the percentage of DM increased. The LP and LP+LB inoculants improved aerobic stability of silages harvested between 18 and 44% DM content.

Evaluation of potential carryover effects associated with limit feeding of gravid Holstein heifers.

Ninety-six Holstein heifers (400±6kg, 15.2±0.1 mo), including 9 with ruminal cannulas, were offered 1 of 3 diets for 180±8 d in a randomized replicated pen design. Dietary treatments included a control diet (C100) and 2 independent limit-fed (LF) diets. The LF diets included one offered at 85% of C100 intake (L85) without an ionophore, and a second containing an ionophore (325 mg/head per day of lasalocid) that was offered at 80% of C100 intake (L80+I). Heifers were evaluated for growth, rumen digesta volume, nutrient excretion, and subsequent lactation performance. Limit-fed heifers consumed less dry matter and neutral detergent fiber, and had greater respective average daily gains (0.96 or 0.89 vs. 0.81 kg/d), and lower feed:gain ratios (9.1 or 9.3 vs. 13.0 kg/kg) compared with heifers offered the C100 diet. No differences in rumen pH, NH(3)-N, or volatile fatty acid concentrations were observed between C100 and LF heifers. Rumen digesta volume, density, and weight were unaffected by LF, and feeding L85 or L80+I did not result in carryover effects for rumen digesta volume when these heifers were offered a common high-fiber diet immediately after the 180-d growth trial. At parturition, no differences were observed for dystocia index, calf body weight, or 7-d postpartum body weight between cows offered LF or C100 diets as heifers. Lactation body weight, dry matter intake, and feed efficiency of cows did not differ between treatments at 45 or 90 d in milk. Milk yield and milk components also were not different between cows that were offered C100 or LF diets as gravid heifers. At 45 d in milk, rumen digesta volume was greater (99.1 vs. 66.1L) for cows offered L85 compared with cows offered L80+I as gravid heifers, but this effect was not observed at 90 d in milk. Limit feeding of gravid Holstein heifers for 180 d did not result in any carryover effects during their first lactation for rumen digesta volume, dry matter intake, or milk yield.

An alternative method to assess 24-h ruminal in vitro neutral detergent fiber digestibility.

Interassay error caused by the inconsistent nature of rumen fluid inoculum confounds comparisons of forage in vitro neutral detergent fiber (NDF) digestibility (NDFD) analyzed in different repetitions or laboratories. Our objective was to determine if priming rumen fluid and allowing it to produce a standard amount of gas before inoculating samples improved assay repeatability. In 2 experiments, we compared interassay error of NDFD estimates between several in vitro assays. In both experiments, dried, ground (1 mm) alfalfa samples (0.5 g) sealed in bags were placed in 125-mL Erlenmeyer flasks and incubated with in vitro media and 10 mL of rumen fluid. In experiment A, rumen fluid was collected from a cannulated cow fed a high forage diet and prepared one of 2 ways; rumen fluid was either used immediately after it was collected and strained through cheese cloth (GVA), or strained fluid was combined with buffer, reducing solution, and 12.5 mg of cellulose/mL of rumen fluid and allowed to produce a consistent amount of gas before inoculation (RPA). The assay was repeated 5 times, with 13 samples per method. In experiment B, inoculum was prepared one of 3 ways; RPA, GVA except rumen fluid was collected and pooled from 2 cows (GVB), or RPA with fluid pooled from 2 cows. The in vitro assays were repeated 5 times with 8 samples per method. Neutral detergent fiber was analyzed using a forage fiber analyzer and 24-h NDFD was determined as: NDFD (% of NDF) = 100 x [(NDF(0h) - NDF(residue))/(NDF(0h))]. Data for each experiment were analyzed using a mixed model procedure and repetition sum of squares for each technique was determined and compared with an F-test to assess technique interassay error. In both experiments, rumen fluid priming significantly reduced repetition sums of squares, 51.2 versus 503 and 23.3 versus 164, compared with the respective GVA or GVB. However, priming significantly decreased NDFD values, 22.5 versus 24.8 and 23.9 versus 26.6%, compared with GVA and GVB, respectively. Priming rumen fluid with cellulose improved in vitro NDFD assay precision, but depressed in vitro NDFD.

Modification of a rumen fluid priming technique for measuring in vitro neutral detergent fiber digestibility.

Recently, we developed an alternate method to measure in vitro neutral detergent fiber (NDF) digestibility (ivNDFD) based on a primed rumen fluid inoculum. Pretreating rumen fluid inoculum with cellulose and holding the inoculum until it generated 0.3 mL of gas/mL of rumen fluid before inoculating forage samples improved ivNDFD assay repeatability but depressed ivNDFD means. Our objective in this study was to determine if pretreating rumen fluid with a mixture of carbohydrates and urea would affect the ivNDFD mean and variance. We also used the modified procedure as a reference assay to calibrate near-infrared reflectance spectroscopy (NIRS) to predict 24-, 30-, and 48-h ivNDFD. Two experiments were completed. In experiment A, 3 ivNDFD assays modified from the method of Goering and Van Soest were evaluated over 24, 28, 48, 54, and 72 h by using dried, ground alfalfa (1 mm) or wheat straw (0.5 g) sealed in Ankom F57 forage fiber bags. Bags were placed individually in 125-mL Erlenmeyer flasks and incubated with Goering and Van Soest media and 10 mL of rumen fluid. Rumen fluid was collected before feeding from 2 cannulated cows fed a high-forage diet and was prepared in 1 of 3 ways: 1) pooled rumen fluid was strained and used immediately to inoculate flasks (modified Goering and Van Soest method); 2) strained, pooled fluid was combined with buffer, reducing solution, and 1.25 mg of primer/mL of rumen fluid and allowed to produce 0.12 mL of gas/mL of rumen fluid before sample inoculation [Combs-Goeser (CG) method]; or 3) the CG method was used without the primer mixture (unprimed method). The assay was repeated 5 times, with 5 time points (24, 28, 48, 54, and 72 h) and 2 subsamples per time point for each method. Neutral detergent fiber was analyzed using an Ankom(200) forage fiber analyzer and ivNDFD was determined as follows: ivNDFD (% of NDF) = 100 x [(NDF(0h) - NDF(residue))/(NDF(0h))]. Results were analyzed using a mixed model procedure, and data were blocked by method to obtain repetition sums of squares, which were compared by an F-test to assess interassay error. Repetition sums of squares were reduced with the CG method compared with the Goering and Van Soest method (19 vs. 228), and mean ivNDFD estimates were similar at 28, 48, and 54 h. In experiment B, 24-, 30-, and 48-h ivNDFD data for 54 feeds were determined in triplicate using the CG method, and corresponding samples were then scanned with an NIRS instrument. Calibrations were computed using partial least squares regression techniques. The NIRS calibration equation R(2) values were 0.93, 0.93, and 0.89 for 24-, 30-, and 48-h ivNDFD. Results suggest that the modified ivNDFD method using rumen fluid primed with a mixture of carbohydrate and urea (CG method) reduced interassay error.

Intake and milk production of cows fed diets that differed in dietary neutral detergent fiber and neutral detergent fiber digestibility.

The objectives of this study were to determine how feeding diets that differed in dietary neutral detergent fiber (NDF) concentration and in vitro NDF digestibility affects dry matter (DM) intake, ruminal fermentation, and milk production in early lactation dairy cows. Twelve rumen-cannulated, multiparous Holstein cows averaging 38 +/- 15 d (+/-standard deviation) in milk, and producing 40 +/- 9 kg of milk daily, were used in a replicated 4 x 4 Latin square design with 28-d periods. Treatment diets were arranged in a 2 x 2 factorial with 28 or 32% dietary NDF (DM basis) and 2 levels of straw NDF digestibility: 1) LD, untreated wheat straw (77% NDF, 41% NDF digestibility) or 2) HD, anhydrous NH(3)-treated wheat straw (76% NDF, 62% NDF digestibility). All 4 diets consisted of wheat straw, alfalfa silage, corn silage, and a concentrate mix of cracked corn grain, corn gluten meal, 48% soybean meal, and vitamins and minerals. Wheat straw comprised 8.5% DM of the 28% NDF diets and 16% DM of the 32% NDF diets. Cows fed 28% NDF and HD diets produced more milk, fat, and protein than those consuming 32% NDF or LD diets. Dry matter intake was greater for cows consuming 28% NDF diets, but intakes of DM and total NDF were not affected by in vitro NDF digestibility. Intake of digestible NDF was greater for cows consuming HD diets. Ruminal fermentation was not affected by feeding diets that differed in NDF digestibility. Ruminal NDF passage rate was slower for cows fed HD than LD. No interactions of dietary NDF concentration and in vitro NDF digestibility were observed for any parameter measured. Regardless of dietary NDF concentration, increased in vitro NDF digestibility improved intake and production in early lactation dairy cows.

Utilization of kura clover-reed canarygrass silage versus alfalfa silage by lactating dairy cows.

The mixture of kura clover (Trifolium ambiguum M. Bieb.) and reed canarygrass (Phalaris arundinacea L.) has proven to be extremely persistent in the northern United States, but information about dairy cow performance on this mixture is lacking. Twenty lactating Holstein cows were used in a crossover design to compare dry matter (DM) intake and milk production from diets containing kura clover-reed canarygrass silage (KRS) or alfalfa (Medicago sativa L.) silage (AS). Forages were cut, wilted, ensiled in horizontal plastic bags, and allowed to ferment for at least 50 d before beginning the feeding experiment. The KRS was approximately 40% kura clover and 60% reed canarygrass. Treatments were total mixed rations formulated with either 57% of total DM from 1) AS or 2) KRS. Experimental periods were 28 d, with the first 14 d for diet adaptation and the last 14 d for measurement of intake and milk production. The neutral detergent fiber (NDF) concentrations of AS and KRS were 37.3 and 47.3%, respectively. The fermentation analyses indicated that both silages underwent a restricted fermentation, producing primarily lactic acid and some acetic acid. Dry matter intake (24.2 vs. 22.8 kg) and 4% fat-corrected milk (32.8 vs. 30.9 kg) were significantly higher for cows fed AS than for cows fed KRS. Cows consumed less NDF (6.7 vs. 8.0 kg) and less digestible NDF (3.0 vs. 4.4 kg) when fed AS diets compared with KRS diets, but the pool of ruminally undegraded NDF was similar (3.7 kg) between diets. Cows produced 1.5 kg of milk/kg of DM consumed regardless of the diet, indicating that digestible NDF of KRS was utilized with similar efficiency as the cell wall constituents of AS, but the intake of cows fed KRS may have been limited by rumen fill. Milk fat concentration tended to be higher for cows fed AS, but the milk true protein concentration and yields of fat and protein did not differ by treatment. Milk urea nitrogen content was higher when cows consumed AS (16.4 mg/ dL) compared with KRS (13.4 mg/dL). The cows fed KRS consumed more NDF but less total DMI, based on the results from this trial with diets formulated to contain approximately 60% of DM as forage, resulting in slightly lower milk yields than cows fed excellent-quality AS. This grass-legume mixture has the potential to be a source of quality forage for dairy cows in regions where alfalfa persistence is a problem.