Management and characteristics of recycled manure solids used for bedding in Midwest freestall dairy herds.

Interest in using recycled manure solids (RMS) as a bedding material for dairy cows has grown in the US Midwest. Cost of common bedding materials has increased in recent years and availability has decreased. Information regarding the composition of RMS and its use as a bedding material for dairy cows in the Midwest is very limited. The objectives of this study were to characterize RMS as a bedding material, observe bedding management practices, document methods of obtaining RMS, and describe housing facilities. We visited 38 Midwest dairy operations bedding freestalls with RMS to collect data. Methods of obtaining RMS for bedding included separation of anaerobic digested manure, separation of raw manure, and separation of raw manure followed by mechanical drum-composting for 18 to 24 h. Average bedding moisture of unused RMS was 72.4% with a pH of 9.16. Unused samples contained (on a dry basis) 1.4% N, 44.9% C, 32.7C:N ratio, 0.44% P, 0.70% K, 76.5% neutral detergent fiber, 9.4% ash, 4.4% nonfiber carbohydrates, and 1.1% fat. Moisture was lowest for drum-composted solids before and after use as freestall bedding. After use in the stalls, digested solids had lower neutral detergent fiber content (70.5%) than drum-composted (75.0%) and separated raw (73.1%) solids. Total N content was greater in digested solids (2.0%) than in separated raw (1.7%) solids. Total bacterial populations in unused bedding were greatest in separated raw manure solids but were similar between digested and drum-composted manure solids. Drum-composted manure solids had no coliform bacteria before use as freestall bedding. After use as bedding, digested manure solids had lower total bacteria counts compared with drum-composted and separated raw manure solids, which had similar counts. Used bedding samples of digested solids contained fewer environmental streptococci than drum-composted and separated raw solids and had reduced Bacillus counts compared with separated raw solids. Coliform counts were similar for all 3 bedding sources. Addition of a mechanical blower post-separation and use of a shelter for storage were associated with reduced fresh-bedding moisture but not associated with bacterial counts. This was the first survey of herds using RMS for bedding in the Midwest. We learned that RMS was being used successfully as a source of bedding for dairy cows. For most farms in the study, somatic cell count was comparable to the average in the region and not excessively high.

Biofilter media mixture ratio of wood chips and compost treating swine odors.

Biofilter media mixtures were compared in 18 pilot-scale biofilters treating pit gases from a swine facility. The compost and wood chips mixtures ranged from 100% wood chips to a 50-50 blend in 10% increments. The effect of three media moisture contents (low, medium, and high) on biofilter performance was also evaluated. Odor and hydrogen sulfide reduction did not change significantly for mixtures with greater than 20% compost. For efficient odor, hydrogen sulfide, and ammonia reduction media moisture must be greater than 40% wb. Media moisture content influenced odor, hydrogen sulfide, and ammonia reduction more than the ratio of compost and wood chips. The count of heterotrophic or sulfur-oxidizing bacteria did not change in a discernable pattern with respect to media mixture or moisture content. As the amount of compost increased in the media mixtures, the pressure drop also increased. Based on this experiment, the recommended mixing ratio of compost to wood chips for biofilters on swine facilities is minimum 30% compost and 70% wood chips by weight.

Market turkey performance, air quality, and energy consumption affected by partial slotted flooring.

Two experiments were conducted with 600 male Large White turkeys to examine performance and health when reared from 5 to 18 wk of age on litter (L) partially slotted flooring (SF), and under two ventilation rates-control and reduced ventilation (80% control). In both experiments, body weights were improved significantly (P < 0.05) for turkeys reared on SF compared to L by 11 and 16% in Experiments 1 and 2, respectively. In comparison to L, SF significantly decreased incidence of leg problems in Experiment 1, whereas the incidence of breast blisters and buttons were increased in Experiment 2. Ammonia levels were reduced with SF, whereas dust levels were increased. Ventilation rate did not affect turkey performance. Ammonia and carbon dioxide levels were increased with reduced ventilation in Experiment 1. Dust levels were not affected by ventilation rate. Supplemental energy use was decreased in the SF system or by reducing the ventilation rate. In comparison to the control ventilation/litter treatment, the greatest decrease in energy use was observed with SF at 80% ventilation rates. Results indicate that the use of SF in a cold climate can improve body weight and substantially reduce energy use when excessive litter moisture is a problem. However, a greater incidence of blisters will limit application of SF due to lowered carcass quality and value.

Dust suppression in swine feed using soybean oil.

Dust generation from swine feed (corn-soybean meal diet) treated with soybean oil was investigated using a cement mixer in a plywood box. Airborne total dust concentrations in the box were measured gravimetrically using a vacuum pump and filters while 12-kg feed samples were constantly mixed. The treatment factors were soybean oil concentration (0, 1, and 3%), corn bulk density (normal, 730 kg/m3 and low, 600 kg/m3), time of oil addition (before vs after grinding the corn), and storage time (0, 7, and 14 d). The feed was a mixture of soybean meal, base mix, and adjusted amounts of ground corn and soybean oil. Adding soybean oil after grinding at 1 and 3% levels to feed made with normal-bulk density corn suppressed total dust generation (3.39 and .99 mg/m3, respectively) (P < .001) compared with the no oil treatment (29.1 mg/m3). The 3% soybean oil treatment suppressed dust generation (.99 mg/m3) more than the 1% soybean oil treatment (3.39 mg/m3) (P < .001). Adding soybean oil after grinding the corn suppressed dust generation more than adding the oil to the corn before grinding for every oil level (P < .001). More dust was generated by feed made from low-bulk density corn than by feed made with normal-bulk density corn at every oil level (P < .001). There was no evidence of any storage time or treatment x storage time interactions.

Aspergillus and other human respiratory disease agents in turkey confinement houses.

The atmosphere of a turkey confinement house on a large Minnesota farm was examined over the course of a year in order to determine levels of airborne contaminants and to evaluate the hazard potential posed by the contaminants to farm workers. Air concentrations of total and respirable dust, ammonia, carbon monoxide, hydrogen sulfide, nitrogen dioxide, methane, and Aspergillus (a fungal respiratory disease agent) were evaluated. Inter- and intra-seasonal variations in confinement house contaminant concentrations were observed. The highest concentrations of dust, ammonia and Aspergillus occurred during the winter months when dust levels averaged 9.3 mg/m3 and ammonia levels averaged 35 parts per million (ppm). Aspergillus levels were lower than expected, never exceeding 73 colony forming units per cubic meter (cfu/m3). Ammonia levels were found to be particularly high during tilling of the confinement house when concentrations greater than 100 ppm were reached. Concentrations of carbon monoxide, hydrogen sulfide, nitrogen dioxide and methane were below detectable levels.

Digestive parameters in young turkeys fed yucca saponin.

Yucca saponin fed in a concentration of 63 ppm to turkey poults at 6 to 14 weeks of age did not significantly improve weight gains, feed conversion, or digestive coefficients. Compared with nonstressed control groups, saponin-fed poults did not have significantly greater average weight gains or feed intakes when stressed by crowding (3 poults per cage) or by adding ammonia to the atmosphere (30 to 35 ppm).