Dr. Charles Maxwell, Dr. Jennie Popp, and Dr. Richard Ulrich - University of Arkansas; Dr. Scott Radcliffe - Purdue University, and Dr. Mark Hanigan - Virginia Tech
Researchers and swine industry representatives have concluded that the maximum level of crude protein reduction, in conjunction with the optimum amino acid inclusion rate, has not been sufficiently determined for widespread acceptance by the swine industry. Reducing the crude protein content of grower and finisher diets has also been repeatedly shown to enhance carcass quality by elevating intramuscular fat.
Maximizing crystalline amino acid use and reducing dietary crude protein in swine diets has been shown to dramatically reduce nitrogen excretion in both nursery and growing/finishing swine which could substantially reduce nitrous oxide (N2O) emissions associated with manure management in swine production. The greenhouse effect of N2O is about 298 times that of CO2.
Therefore, we are using wean-to-finish facilities at the University of Arkansas to evaluate a three phase nursery and a 5 phase grow/finish feeding program with Ractopamine supplement during the final 3-week phase to identify diets that maximize use of crystalline amino acids and minimize crude protein without negatively impacting gain, carcass composition or quality.
A detailed protocol has been developed with input from the entire committee, industry and selected University Faculty with swine nutrition expertise. The growing/finishing study was completed on April 25, 2012.
The anticipated result of this work is the development of feeding protocols which improve dietary nitrogen utilization leading to reduction in nitrous oxide emissions from manure management. There may be indirect benefits associated with the potential reduction in the quantity of soy meal used as a source of crude protein. These benefits will be quantified through the life cycle analysis and costing program areas
Dr. Charles Maxwell - University of Arkansas
This portion of the project will utilize wean-to-finish facilities at the University of Arkansas to develop a dietary program from weaning to market using nursery, conventional growing/finishing, and Ractopamine-fed finishing pigs. Feeding programs implemented include; a three phase nursery feeding program ,and a 5-phase feeding program during growing/finishing with Ractopamine fed during the final 4-week phase. PIC genetics which represent over 40 % of U. S. commercial animals will be used (PIC line C-29 X 380).
Each experiment will consist of split-sex pens with 24 pens of gilts and 24 pens of barrows, and with a maximum of 9 pigs/pen through the nursery period and 6 pigs/pen during growing/finishing. Our goal is develop diets that maximize use of crystalline amino acids and minimize CP without negatively impacting gain, carcass composition or yield.
The Ractopamine experiment will have incremental levels of 0.09% lysine with corresponding reductions in CP. All other indispensable amino acids will be added to meet the ideal protein (NRC, 1998) requirement. Individual pig weights will be measured bi-weekly, and feed disappearance will be recorded at the end of each phase to calculate ADG, ADFI, and gain-to-feed ratio (G:F). Manure samples will be collected at the end of each phase in each study for nutrient composition analysis, which will be used to validate the animal physiology model and to estimate GHG emissions (DNDC model).
In finishing studies, dressing % and % lean yield will be calculated methodically from ancillary data recorded within each treatment group. Carcasses will then be fabricated into primal cuts, and bone-in hams from left sides will be analyzed for lean composition using a ham electrical conductivity (TOBEC) unit (Cargill Meat Solutions, Wichita, KS).
Dr. Charles Maxwell
Phone: (479) 575-2111
Dr. Mark Hanigan - Virginia Tech
Current nutritional requirement models for swine are focused on partitioning of dietary energy and amino acids to maintenance, growth, gestation, and lactation. Little focus is placed on predicting nutrient excretion, and thus these models cannot be used to provide inputs to an emissions model. Models that predict excretion of energy, protein, and phosphorus have been developed, but have not been evaluated for the accuracy of predictions; and evaluations that have been undertaken focus on predictions of growth and body composition, not nutrient excretion.
GHG emissions from manure storage facilities can be predicted from manure composition, underscoring the need for a robust animal model capable of predicting both animal performance and nutrient excretion. Prediction of GHG emissions from swine manure requires knowledge of N and volatile solids content, neither of which are provided by current NRC predictions.
The NRC swine model (1998) will be enhanced with equations to predict fecal flow of volatile solids and N and urinary N output. Growth and N retention models of the NRC will also be enhanced to include Ractopamine and health status effects on growth and rates of excretion. Both effects will be applied to the retained N equations. The enhanced equation set will be assessed for accuracy using data from published studies and this project.
Predictions of animal performance and excreted volatile solids and N will be calibrated and validated through the experimental work described in the nitrogen mitigation study section. The model will then be statistically analyzed to provide an assessment of model accuracy and consistency. The results will be used to determine if additional driving variables are needed, or if some can be removed. This effort will require several iterations and the resulting model is likely to be much more complicated than initial representations.
Data from the nitrogen mitigation growth and nitrogen excretion studies will be utilized in enhancement of an animal model capable of predicting swine performance and excretion of nitrogen, carbon, and volatile solids (inputs required by the DNDC model). The growth model developed by the workers at UC-Davis and the recently released Nutrient Requirements of Swine (NRC) eleventh revised edition will be used as a starting point for model development. Equations describing the response to dietary protein and amino acid additions will be evaluated for accuracy, and the effects of Paylean on animal performance and manure nutrient output will be encoded and tested for accuracy. This work is scheduled to precede and utilize data from the UA trial and literature sources. The model will be further evaluated in the 5th year using the Purdue data set.
Dr. Mark Hanigan
Phone: (540) 231-0967
Dr. Scott Radcliffe and Dr. Brian Richert - Purdue University
A study will be initiated to quantify the effects of the dietary nitrogen reduction mitigation on GHG emissions and animal performance on a pen basis with pen size and animal numbers more consistent with industry standards. This study will generate GHG emission data for model validation and is scheduled to be conducted in the Swine Environmental Research Building (see video) at Purdue in months 24 to 48 after initiation of the project. PI’s at Purdue have initiated the process through the Purdue system to purchase the needed equipment for modification of the 12 – room environmental facility preparing for the upcoming large scale studies at Purdue in subsequent years of the project that follow the preliminary work at UA and VT.
Dr. Richert recently discussed his efforts pertaining to this project during the July 2012 installment of the eXtension-Livestock,Poultry, and Environmental Learning Center (LPELC) webcast series; his presentation and the following Q&A session can be viewed here.
Dr. Scott Radcliffe
Phone: (765) 496-7718
Dr. Brian Richert