Mark S. Honeyman

Carbon, nutrient, and mass loss during composting

Hoop manure (a mixture of partially decomposed pig manure and cornstalks from swine fed in hoop structures) was the subject of a nitrogen mass balance during the feeding period. The manure was then composted in windrows to investigate C, nutrient, and mass loss during the composting process. Feeding cycle mass balance results indicated that N losses from the bedded pack ranged from 24 to 36%. Composting treatments included construction with and without a manure spreader and subsequent management with and without turning. Significantly greater losses of mass, C, K, and Na were found in the turned windrow treatment. However, composting in turned windrows proceeded at a much faster rate, with temperatures dropping out of the thermophilic range within 21 days. Composting without turning was less rapid, with temperatures remaining in the thermophilic range to the end of the 42-day trial. Mass reduction and C loss was significantly higher in the turned windrows than in the unturned windrows. Nitrogen loss was between 37 and 60% of the initial N, with no significant effect from turning. It appears that the low initial C:N ratio (between 9:1 and 12:1) was the most critical factor affecting the N loss in this composting process. Phosphorus, K, and Na losses were also high during composting, which could be due to runoff and leaching from the hoop manure. These elements may be significant contributors to surface and groundwater pollution through runoff and leaching. Additional research is planned to understand the extent of losses through volatilization, runoff, and leaching during composting.

Growth performance, carcass characteristics, meat quality, and tissue histology of growing pigs fed crude glycerin-supplemented diets.

The effects of dietary crude glycerin on growth performance, carcass characteristics, meat quality indices, and tissue histology in growing pigs were determined in a 138-d feeding trial. Crude glycerin utilized in the trial contained 84.51% glycerin, 11.95% water, 2.91% sodium chloride, and 0.32% methanol. Eight days postweaning, 96 pigs (48 barrows and 48 gilts, average BW of 7.9 +/- 0.4 kg) were allotted to 24 pens (4 pigs/pen), with sex and BW balanced at the start of the experiment. Dietary treatments were 0, 5, and 10% crude glycerin inclusion in corn-soybean meal-based diets and were randomly assigned to pens. Diets were offered ad libitum in meal form and formulated to be equal in ME, sodium, chloride, and Lys, with other AA balanced on an ideal AA basis. Pigs and feeders were weighed every other week to determine ADG, ADFI, and G:F. At the end of the trial, all pigs were scanned using real-time ultrasound and subsequently slaughtered at a commercial abattoir. Blood samples were collected pretransport and at the time of slaughter for plasma metabolite analysis. In addition, kidney, liver, and eye tissues were collected for subsequent examination for lesions characteristic of methanol toxicity. After an overnight chilling of the carcass, loins were removed for meat quality, sensory evaluation, and fatty acid profile analysis. Pig growth, feed intake, and G:F were not affected by dietary treatment. Dietary treatment did not affect 10th-rib backfat, LM area, percent fat free lean, meat quality, or sensory evaluation. Loin ultimate pH was increased (P = 0.06) in pigs fed the 5 and 10% crude glycerin compared with pigs fed no crude glycerin (5.65 and 5.65 versus 5.57, respectively). Fatty acid profile of the LM was slightly changed by diet with the LM from pigs fed 10% crude glycerin having less linoleic acid (P < 0.01) and more eicosapentaenoic acid (P = 0.02) than pigs fed the 0 or 5% crude glycerin diets. Dietary treatment did not affect blood metabolites or frequency of lesions in the examined tissues. This experiment demonstrated that pigs can be fed up to 10% crude glycerin with no effect on pig performance, carcass composition, meat quality, or lesion scores.

Effect of Windrow Turning and Seasonal Temperatures on Composting of Hog Manure from Hoop Structures

A study was undertaken to investigate the effect of windrow turning on composting of hoop manure (a mixture of partially decomposed hog manure and cornstalk). Three series of experiments were conducted: one during summer, one during winter, and one during spring. In all three series of experiments, windrows were either turned (once a week) or left unturned during the composting process, which lasted for 42 days. The effects of windrow turning were evaluated by measuring the physicochemical properties (temperature, oxygen concentration water content, pH, organic matter, and nutrients) of the hoop manure during composting. Turning affected a number of important physical and chemical parameters such as temperature, oxygen concentrations, and C and mass loss. The temperature of the unturned windrows took longer to drop to ambient temperature, had lower oxygen concentration, and C and mass loss than the turned windrows. These results suggest that the decomposition rate in turned windrows is much faster than the unturned ones. However, the final product from the two composting treatments (turned and unturned windrows) was similar in terms of the organic matter, nutrient contents, and C:N ratios. N loss was a major problem during composting of hoop manure. As much as 60% of the N in the hoop manure (both in turned and unturned windrows) was lost during composting, indicating that composting has significantly reduced the value of hoop manure as N fertilizer. These losses could be attributed to ammonia volatilization, leaching, and run-off. Overall, composting was similar in all three seasons (summer, winter, and spring). This study demonstrated that hoop manure could be successfully composted during winter.

Effects of triticale-based diets on finishing pig performance and pork quality in deep-bedded hoop barns

Effects of triticale diets on pig performance and pork quality were evaluated in summer and winter. Diets were: corn-soy, 40% triticale, or 80% triticale. Pigs (72kg) were fed 49d. Loins were evaluated for meat and fat quality and sensory evaluation. Average daily gain decreased as triticale inclusion increased (P<0.01). Feed intake was similar. Pigs fed corn-soy had the greatest and those fed 80% triticale had least gain:feed ratio (P<0.05). In summer, pigs fed corn-soy had largest and those fed 80% triticale diet had smallest loin muscle area (P<0.05) based on ultrasound scan. During summer, ultimate pH was higher (P⩽0.001) and, loin purge and shear force were lower (P<0.05). Diet did not affect sensory evaluation or fatty acid profile of loins. During summer, total MUFA were more and total PUFA were less (P⩽0.01). Triticale fed to pigs in hoop barns slightly decreased growth without compromising pork quality.

Environment-friendly swine feed formulation to reduce nitrogen and phosphorus excretion

The nutrient composition of swine excreta can be altered by manipulating the composition of the pigs diet Several approaches are reviewed: feeding according to the pigs growth phase, formulation according to the feeds digestible amino acids, use of crystalline amino acids, the ideal protein approach, formulation according to available phosphorus, and the addition ofphytase enzymes. Each has the potential to lower nitrogen or phosphorus excretion levels. Together they can dramatically reduce the nitrogen and phosphorus concentration of swine manure, which could be a major advantage in regions with a high density of swine or for swine operations with limited access to arable land. However, the value of the swine manure would be much less as a fertilizer because these two elements are important plant nutrients.

Reducing food insecurity in developing countries through meat production: the potential of the guinea pig ( Cavia porcellus )

Global poverty and food insecurity continue to remain critical issues, especially in rural areas. Developing and fostering agricultural systems that not only require low to moderate amounts of economic capital and few external inputs but also maintain and enhance the resource base of production are key features of sustainable agricultural development. Sustainable agricultural development, including diversifying smallholder production to include livestock, is a pragmatic approach to address both rural poverty and food insecurity. Livestock play important roles in the lives of humans as converters, recyclers and banks of nutrients. Smallholders raise a diversity of livestock species and often raise multiple species simultaneously. High fecundity, diet flexibility and adaptability to a wide range of housing and management approaches are critical traits of livestock species well suited for producing meat for home consumption and marketing in the context of rural smallholders. Swine (Sus scrofa) and chicken (Gallus domesticus) meet many of these criteria and are well known livestock species. This paper examines the potential for a less common species of livestock, guinea pig (Cavia porcellus) to enhance food security and increase household income of rural smallholders. Although cultural acceptance of guinea pig as a source of nutrition and income is less ubiquitous than that of swine, chicken and other species, the biological, ecological and economic advantages of guinea pig deserve further examination by those working to alleviate global poverty and food insecurity.

Performance of a Swedish deep-bedded feeder pig production system in Iowa

At the Iowa State University Armstrong Research and Demonstration Farm in southwestern Iowa, a Swedish feeder pig production system was studied and demonstrated for 2-1/2 years. The system is based mainly on straw bedding, simple buildings, and intensive management. The system was designed to minimize pig stress and use of subtherapeutic antibiotics in the feed. Gestating and breeding sows were group-housed in a hooped structure with individual feeding stalls. Large round bales of cornstalks were used for bedding. Farrowing, lactation, and nursery phases were housed in a remodeled hog house. Cubicles with rollers and oat straw bedding were used for farrowing. Two groups of Yorkshire × Landrace sows bred to Hampshire boars produced feeder pigs in the system. Conception rates averaged 95%, and litter size averaged 11.3 live pigs/litter. Sows were allowed to select their own bedded farrowing cubicle. Prewean pig mortality, mostly from crushing, was high (29%), occurring primarily in the first 3 days. At 2 weeks of age the cubicles were removed and group lactation occurred. After group lactation the average pig weaning weight was 10.4 kg at 33.9 days of age. At weaning the sows were removed, and the pigs remained in the bedded farrowing/lactation room for 24 additional days. The pigs weighed 24.8 kg at 60 days of age, and overall nursery phase average daily weight gain was 549 g/day. Overall pig health was excellent with no major clinical diseases confirmed. The demonstration exceeded reproductive performance measures of typical small- and mid-sized Iowa farms.

Sustainable swine production in the U.S. Corn Beit

Swine production is a major component of Corn Belt agriculture; thus development of a sustainable Corn Belt agriculture depends on sustainable swine production systems. Swine are versatile enough to adapt to sustainable concepts, and swine production raises several opportunities to enhance sustainability. These include: 1) feeding with increased use of forages and by-product feeds; 2) nutrient cycling through improved handling of manure; 3) low-capital housing systems that offer an improved environment for the operator and reduced financial risk; 4) management systems suited to the swines behavior; and 5) preventive approaches to swine health and a broader genetic base. The challenge beyond identifying the opportunities is research and technology transfer and incorporation of sustainable concepts into ecologically based swine production systems.

Nonsolar energy use and one-hundred-year global warming potential of Iowa swine feedstuffs and feeding strategies.

Demand for nonsolar energy and concern about the implications of fossil fuel combustion have encouraged examination of energy use associated with agriculture. The United States is a global leader in pig production, and the United States swine industry is centered in Iowa. Feed is the largest individual input in pig production, but the energy consumption of the Iowa swine feed production chain has yet to be critically examined. This analysis examines nonsolar energy use and resulting 100-yr global warming potential (GWP) associated with the swine feed production chain, beginning with cultivation of crops and concluding with diet formulation. The nonsolar energy use and accompanying 100-yr GWP associated with production of 13 common swine feed ingredients are estimated. Two diet formulation strategies are considered for 4 crop sequence x ingredient choice combinations to generate 8 crop sequence x diet formulation scenarios. The first formulation strategy (simple) does not include synthetic AA or phytase. The second strategy (complex) reduces CP content of the diet by using L-lysine to meet standardized ileal digestibility lysine requirements of pigs and includes the exogenous enzyme phytase. Regardless of crop sequence x diet formulation scenario, including the enzyme phytase is energetically favorable and reduces the potential excretion of P by reducing or removing inorganic P from the complete diet. Including L-lysine reduces the CP content of the diet and requires less nonsolar energy to deliver adequate standardized ileal digestible lysine than simply feeding soybean meal. Replacing soybean meal with full-fat soybeans is not energetically beneficial under Iowa conditions. Swine diets including dried distillers grains with solubles and crude glycerol require approximately 50% more nonsolar energy inputs than corn-soybean meal diets or corn-soybean meal diets including oats. This study provides essential information on cultivation, processing, and manufacture of swine feed ingredients in Iowa that can be coupled with other models to estimate the nonsolar energy use and 100-yr GWP of pig production.

Nutrient Losses from Unlined Bedded Swine Hoop Structures and an Associated Windrow Composting Site

Mass balance analysis of livestock manure management systems can offer important insight into the flows and losses of nutrients and potential pollutants. This study describes the objectives, design, and two years of results from a field study examining the nutrient losses from bedded swine structures and an associated composting site. Nutrient mass balances have been completed on three groups of pigs in naturally ventilated hoop structures, along with the corresponding three composting trials at the outdoor windrow composting site. Soil core nutrient analysis and mass balances on nutrients in the swine production system and composting piles have been used to assess losses to the environment. The mass balance analysis of deep bedded hoop structures identified significant N losses from the bedded pack (54 ± 6% of the excreted manure; 3.9 kg/pig) but negligible P losses in the hoop. Both N and P losses at the compost site were significant (19 ± 10% and 21 ± 21% of the excreted manure respectively). After losses in both the hoop and the composting process, the nutrient quantities remaining were 1.9 ± 0.4 kg N/pig and 1.0 ± 0.3 kg P/pig. 10% or less of the N losses from the hoop accumulated in the top 1.2 m of soil, and that net accumulation was entirely in the first year. Most N losses within the hoop structure appear to be in gaseous forms, e.g. N2, N2O, and NH3. Improved management of these gaseous losses in bedded livestock systems will be important to making these systems environmentally sustainable. Although soil sample variability precluded a direct correlation between nitrogen losses and soil accumulation at the composting site, high apparent soil accumulations did indicate that a considerable fraction of the N losses observed at the composting site are being leaching into the soil. Design and management strategies to mitigate this leaching loss are likely to be necessary for manure composting facilities in humid regions located near vulnerable groundwater resources.