Efficacy of recycled sand or organic solids as bedding sources for lactating cows housed in freestalls.

Our objective was to compare the composition of bedding materials and manure, cow welfare and hygiene assessments, measures of milk production and quality, and incidence of mastitis during a 3-yr trial with lactating Holstein cows housed in a freestall barn containing 4 identical pens with 32 freestalls/pen. Bedding systems evaluated included deep-bedded organic manure solids (DBOS), shallow-bedded manure solids spread over mattresses (MAT), deep-bedded recycled sand (RSA), and deep-bedded new sand (NSA). The experiment was designed as a 4 × 4 Latin square with 4 bedding systems and 4 experimental periods, but was terminated after 3 yr following discussions with the consulting statistician; therefore, data were analyzed as an incomplete Latin square. A total of n = 734 mostly primiparous cows (n = 725 primiparous, n = 9 multiparous; 224 to 267 cows/yr) were enrolled in the trial. Before placement in freestalls, organic solids (OS) exhibited lower concentrations of dry matter (36.5 vs. 94.3%), and greater concentrations of volatile solids, C, N, NH4-N, P, water-extractable P, K, and S compared with RSA or NSA. Cow comfort index was greater for sand-bedded systems compared with those using OS (88.4 vs. 82.8%). Cows bedded in systems using OS (DBOS and MAT) exhibited greater mean hock scores (1 = no swelling, no hair loss; 2 = no swelling, bald area on hock) than those bedded in sand (1.25 vs. 1.04), but this effect was entirely associated with use of mattresses (MAT), which differed sharply from DBOS (1.42 vs. 1.07). Generally, hygiene scores for legs, flanks, and udders were numerically similar for DBOS, NSA, and RSA bedding systems, and differences between bedding systems were associated entirely with MAT, yielding detectable contrasts between MAT and DBOS for legs (2.94 vs. 2.20), flanks (2.34 vs. 1.68), and udders (1.83 vs. 1.38). No significant contrast comparing bedding systems was detected for measures of milk production or quality. Documented cases of clinical mastitis requiring treatment ranged from a low rate of 7.4 cases/yr for RSA to a high of 23.1 cases/yr for DBOS, based on a mean enrollment of 60.7 to 63.0 cows/treatment per yr. Cows bedded with OS exhibited a greater incidence of mastitis than those bedded with sand (19.0 vs. 8.4 cases/yr), but no differences were observed for comparisons within individual bedding-material types. Collectively, these results generally favored use of sand-bedding materials over systems using OS.

Voluntary intake and digestibility by sheep of alfalfa ensiled at different moisture concentrations following fertilization with dairy slurry.

Dairy slurry is used commonly as an animal-sourced fertilizer in agronomic production. However, residual effects of slurry application on intake and digestibility of alfalfa (Medicago sativa L.) silage from subsequent harvests are not well known. The objective of this study was to determine if moisture concentration of alfalfa silage and timing of dairy slurry application relative to subsequent harvest affected intake and digestibility by sheep. Katahdin crossbred ewes (n = 18; 48 ± 5.3 kg) in mid-gestation were stratified by BW and allocated randomly in each of two periods to one of six treatments arranged in a two × three factorial arrangement. Treatments consisted of recommended (RM; 46.8%) or low (LM; 39.7%) moisture at baling after either no slurry application (NS), slurry application to stubble immediately after removal of the previous cutting (S0), or slurry application 14 d after removal of the previous cutting (S14). Silages were chopped through a commercial straw chopper, packed into plastic trash cans, and then offered to ewes within 4 d of chopping. Period 1 of the intake and digestion study consisted of a 14-d adaptation followed by a 7-d fecal collection period. Period 2 followed period 1 after a 4-d rest and consisted of an 11-d adaptation followed by 7 d of fecal collection. Ewes were housed individually in 1.4 × 4.3-m pens equipped with rubber mat flooring. Feces were swept from the floor twice daily, weighed, and dried at 50 °C. Ewes had ad libitum access to water and were offered chopped silage for a minimum of 10% refusal (DM). Blood samples were collected immediately prior to feeding, and 4 and 8 h after feeding on the day prior to the end of each period. Organic matter intake (g/kg BW) and OM digestibility tended (P < 0.10) to be, and digestible OM intake (g/kg BW) was reduced by slurry application. Lymphocytes (% of total white blood cells) were greater (P < 0.05) from LM vs. RM and from NS vs. S0 and S14. Red blood cell concentrations were greater (P < 0.05) from S14 vs. S0 and from S0 and S14 vs. NS. Serum urea N concentrations did not differ (P > 0.17) across treatments. Therefore, moisture concentration of alfalfa silage within the range used in this study may not affect voluntary intake or digestibility, but slurry application may have an effect on digestible OM intake. Also, moisture concentration of alfalfa silage and time of dairy slurry application may affect specific blood hemograms.

Net effects of nitrogen fertilization on the nutritive value and digestibility of oat forages.

Applications of soil amendments containing N are part of routine forage-management strategies for grasses, with a primary goal of increasing forage yield. However, the effects of N fertilization on forage nutritive value, estimates of energy density, and in vitro dry matter or neutral detergent fiber disappearance sometimes have been erratic or inconsistent. Our objectives were to evaluate the effects of N fertilization on the nutritive value of a single cultivar (ForagePlus, Kratz Farms, Slinger, WI) of fall-grown oat fertilized at planting with 20, 40, 60, 80, or 100 kg of N/ha of urea or 2 rates of dairy slurry (42,300 or 84,600 L/ha). Nitrogen fertilization exhibited consistent effects on fiber components; forages fertilized with urea or dairy slurry had greater concentrations of fiber components compared with those harvested from unfertilized check plots (0 kg of N/ha), and fiber concentrations increased linearly with urea fertilization rate. In contrast, concentrations of water-soluble carbohydrates were greatest for unfertilized forages (21.2%), but declined linearly with urea fertilization, exhibiting a minimum of 13.5% at the 80 kg of N/ha urea application rate. Similarly, nonfiber carbohydrates also declined linearly, from 34.8% for unfertilized check plots to a minimum of 24.6% at the 80 kg of N/ha urea application rate. Fertilization with urea resulted in consistent linear increases in crude protein (CP), neutral detergent soluble CP, neutral detergent insoluble CP, and acid detergent insoluble CP; however, the partitioning of CP on the basis of association with specific fiber fractions could not be related to N fertilization when concentrations were expressed on a percentage of CP basis. The summative calculation of energy, expressed as total digestible nutrients was closely related to N fertilization rate during both the 2013 (y = -0.038x + 72.2; R2 = 0.961) and 2014 (y = -0.040x + 69.2; R2 = 0.771) production years. Following 30- or 48-h incubations in buffered rumen fluid, in vitro dry matter disappearance was greater for unfertilized forages compared with those fertilized with either urea or dairy slurry, and disappearance declined linearly with urea fertilization rate; however, these responses were not detected for neutral detergent fiber disappearance. Overall, the forage nutritive value of fall-grown oat declined mildly in response to N fertilization, but these responses were not nearly strong enough to offset the advantages obtained by improved forage yields.

Effects of dairy slurry on silage fermentation characteristics and nutritive value of alfalfa.

Dairy producers frequently ask questions about the risks associated with applying dairy slurry to growing alfalfa (Medicago sativa L.). Our objectives were to determine the effects of applying dairy slurry on the subsequent nutritive value and fermentation characteristics of alfalfa balage. Dairy slurry was applied to 0.17-ha plots of alfalfa; applications were made to the second (HARV1) and third (HARV2) cuttings during June and July of 2012, respectively, at mean rates of 42,400 ± 5271 and 41,700 ± 2397 L/ha, respectively. Application strategies included (1) no slurry, (2) slurry applied directly to stubble immediately after the preceding harvest, (3) slurry applied after 1 wk of post-ensiled regrowth, or (4) slurry applied after 2 wk of regrowth. All harvested forage was packaged in large, rectangular bales that were ensiled as wrapped balage. Yields of DM harvested from HARV1 (2,477 kg/ha) and HARV2 (781 kg/ha) were not affected by slurry application treatment. By May 2013, all silages appeared to be well preserved, with no indication of undesirable odors characteristic of clostridial fermentations. Clostridium tyrobutyricum, which is known to negatively affect cheese production, was not detected in any forage on either a pre- or post-ensiled basis. On a pre-ensiled basis, counts for Clostridium cluster 1 were greater for slurry-applied plots than for those receiving no slurry, and this response was consistent for HARV1 (4.44 vs. 3.29 log10 genomic copies/g) and HARV2 (4.99 vs. 3.88 log10 genomic copies/g). Similar responses were observed on a post-ensiled basis; however, post-ensiled counts also were greater for HARV1 (5.51 vs. 5.17 log10 genomic copies/g) and HARV2 (5.84 vs. 5.28 log10 genomic copies/g) when slurry was applied to regrowth compared with stubble. For HARV2, counts also were greater following a 2-wk application delay compared with a 1-wk delay (6.23 vs. 5.45 log10 genomic copies/g). These results suggest that the risk of clostridial fermentations in alfalfa silages is greater following applications of slurry. Based on pre- and post-ensiled clostridial counts, applications of dairy slurry on stubble are preferred (and less risky) compared with delayed applications on growing alfalfa.

Dairy slurry application method impacts ammonia emission and nitrate in no-till corn silage.

Reducing ammonia (NH3) emissions through slurry incorporation or other soil management techniques may increase nitrate (NO3) leaching, so quantifying potential losses from these alternative pathways is essential to improving slurry N management. Slurry N losses, as NH3 or NO3 were evaluated over 4 yr in south-central Wisconsin. Slurry (i.e., dairy cow [Bos taurus] manure from a storage pit) was applied each spring at a single rate (-75 m3 ha(-1)) in one of three ways: surface broadcast (SURF), surface broadcast followed by partial incorporation using an aerator implement (AER-INC), and injection (INJ). Ammonia emissions were measured during the 120 h following slurry application using chambers, and NO3 leaching was monitored in drainage lysimeters. Yield and N3 uptake of oat (Avena sativa L.), corn (Zea mays L.), and winter rye (Secale cereale L.) were measured each year, and at trial's end soils were sampled in 15- to 30-cm increments to 90-cm depth. There were significant tradeoffs in slurry N loss among pathways: annual mean NH3-N emission across all treatments was 5.3, 38.3, 12.4, and 21.8 kg ha(-1) and annual mean NO3-N leaching across all treatments was 24.1, 0.9, 16.9, and 7.3 kg ha' during Years 1, 2, 3, and 4, respectively. Slurry N loss amounted to 27.1% of applied N from the SURF treatment (20.5% as NH3-N and 6.6% as NO,-N), 23.3% from AER-INC (12.0% as NH3-N and 11.3% as NO3-N), and 9.19% from INJ (4.4% as NH3-N and 4.7% as NO3-N). Although slurry incorporation decreased slurry N loss, the conserved slurry N did not significantly impact crop yield, crop N uptake or soil properties at trial's end.

Ammonia emissions from dairy production in Wisconsin.

Ammonia gas is the only significant basic gas that neutralizes atmospheric acid gases produced from combustion of fossil fuels. This reaction produces an aerosol that is a component of atmospheric haze, is implicated in nitrogen (N) deposition, and may be a potential human health hazard. Because of the potential impact of NH3 emissions, environmentally and economically, the objective of this study was to obtain representative and accurate NH3 emissions data from large dairy farms (>800 cows) in Wisconsin. Ammonia concentrations and climatic measurements were made on 3 dairy farms during winter, summer, and autumn to calculate emissions using an inverse-dispersion analysis technique. These study farms were confinement systems utilizing freestall housing with nearby sand separators and lagoons for waste management. Emissions were calculated from the whole farm including the barns and any waste management components (lagoons and sand separators), and from these components alone when possible. During winter, the lagoons' NH3 emissions were very low and not measurable. During autumn and summer, whole-farm emissions were significantly larger than during winter, with about two-thirds of the total emissions originating from the waste management systems. The mean whole-farm NH3 emissions in winter, autumn, and summer were 1.5, 7.5, and 13.7% of feed N inputs emitted as NH3-N, respectively. Average annual emission comparisons on a unit basis between the 3 farms were similar at 7.0, 7.5, and 8.4% of input feed N emitted as NH3-N, with an annual average for all 3 farms of 7.6 +/- 1.5%. These winter, summer, autumn, and average annual NH3 emissions are considerably smaller than currently used estimates for dairy farms, and smaller than emissions from other types of animal-feeding operations.

Effect of manure application timing, crop, and soil type on phosphorus leaching.

Phosphorus (P) leaching losses from manure applications may be of concern when artificial drainage systems allow for hydrologic short-cuts to surface waters. This study quantified P leaching losses from liquid manure applications on two soil textural extremes, a clay loam and loamy sand soil, as affected by cropping system and timing of application. For each soil type, manure was applied at an annual rate of 93 800 L ha(-1) on replicated drained plots under maize (Zea mays L.) in early fall, late fall, early spring, and as a split application in early and late spring. Manure was applied on orchardgrass (Dactylis glomerata L.) in split applications in early fall and late spring, and early and late spring. Drain water was sampled at least weekly when lines were flowing, and outflow rate and total P content were determined. High P leaching losses were measured in the clay loam as soon as drain lines initiated flow after manure application. Flow-weighted mean P leaching losses on clay loam plots averaged 39 times higher (0.504 mg L(-1)) than those on loamy sand plots (0.013 mg L(-1)), and were above the USEPA level of concern of 0.1 mg L(-1). Phosphorus losses varied among application seasons on the clay loam soil, with highest losses generally measured for early fall applications. Phosphorus leaching patterns in clay loam showed short-term spikes and high losses were associated with high drain outflow rates, suggesting preferential flow as the main transport mechanism. Phosphorus leaching from manure applications on loamy sand soils does not pose environmental concerns as long as soil P levels remain below the saturation level.

Ryegrass cover crop effects on nitrate leaching in spring barley fertilized with 15NH415NO3.

Cover crops are a management option to reduce NO3 leaching under cereal grain production. A 2-yr field lysimeter study was established in Uppsala, Sweden, to evaluate the effect of a perennial ryegrass (Lolium perenne L.) cover crop interseeded in barley (Hordeum vulgare L.) on NO3-N leaching and availability of N to the main crop. Barley and ryegrass or barley alone were seeded in mid-May 1992, in lysimeters (03-m diam. x 1.2-m depth) of an undisturbed, well-drained, sandy loam soil. Fertilizer N was applied at the same time as labeled l5NH415NO3 (10 atom % 15N) at a rate of 100 kg N ha(-1). In 1993, barley was reseeded in May in the lysimeters but with nonlabeled NH4NO3 and no cover crop (previous year's cover crop incorporated just prior to seeding). Barley yields and total and fertilizer N uptake in Year 1 (1992) were unaffected by cover crop. Total aboveground N uptake by the ryegrass was 28 kg ha(-1) at the time of incorporation the following spring. Recovery of fertilizer-derived N in May 1993 was about 100%; 53% in soil, 46% in barley, <2% in ryegrass, and negligible amounts in leachate. In May 1994, the corresponding figures were: 32% in soil, <3% in barley, and, again, negligible amounts in leachate. The cover crop reduced concentrations of NO3-N in the leachate considerably (<5 mg L(-1), compared with 10 to 18 mg L(-1) without cover crop) at most sampling times from November 1992 to April 1994, and reduced the total amount of NO3-N leached (22 compared with 8 kg ha(-1)).