S1012: Nutritional Systems for Swine to Increase Reproductive Efficiency (S-288)
Statement of Issues and Justification
Introduction:Swine production is globally distributed. The U.S. is the world's second largest swine producing country behind China. In 2001, an estimated 98 million hogs were slaughtered in the U.S. for an estimated gross on-farm value of $12 billion. The average daily inventory was 59 million animals, of which 6.2 million were sows (USDA, 2002). Swine production is driven by the fact that pork continues to be one of the major high quality sources of protein in human diets. The average per capita consumption of pork in the U.S. is 21.6 kg (USDA, 2002).
Need as indicated by the stakeholders:
Swine enterprises constitute a major source of on-farm income in the Southern Region of the U.S., and production continues to increase. Swine production in the Southern Region represents 27% of U.S. production, up from 25% five years ago. The most rapidly growing component of swine production in the Southern Region is in sow farms producing feeder pigs that are shipped to the Midwest for finishing and market. This trend is attributed to favorable environmental conditions and the availability of labor and interest in contract swine production. The Southern Region has a more favorable climate during the winter months than many of the swine producing states of the Midwest; however, high environmental temperatures during the summer affect reproductive efficiency.
A primary factor affecting profitability of swine production is sow productivity, and optimum nutrition of the sow is essential to maximize sow productivity. An ideal nutrition program should provide adequate nutrients to maximize sow productivity while minimizing excreted nutrients and feed costs. The continuing trends to earlier weaning, confinement housing, and intensive production schedules place biological demands on the sow that make high performance difficult to obtain and maintain. An increase in the number of pigs marketed per sow per year, through improved sow nutrition, would result in increased profitability by allocating the fixed sow costs over more pigs.
Swine production in the Southern Region is concentrated in certain areas, much like swine production throughout the U.S. This concentrated production results in a concentration of waste applied to the land. The amount and nutrient composition of this waste may exceed the capacity of the land in these areas for its use as a fertilizer. Sows contribute approximately 16% of the total nitrogen from pig production enterprises, and nitrogen retention in sows averages 20 to 40% with 60 to 80% of nitrogen intake excreted to the environment. The potential impact of nutrient pollution of the environment is probably the major issue facing commercial swine producers in the U.S. Managing animal waste will be a much greater challenge in the future because of the volume produced for a given land mass.
The joint task force of Southern Agricultural Experiment Stations, USDA, and swine industry representatives (Swine Research Needs in the Southern Region, 1976) emphasized that sow research should have a high priority. This report stated that an important researchable area is to identify the optimum level of each nutrient for the gestating-lactating sow. Similarly, the research committee of the National Pork Producers Council identified improvements in sow nutrition as an area needing further research. The current S-288 committee has met with members of the American Feed Industry Association, the National Pork Board, and representatives from large feed companies to get their assessment of research needs by the industry. The research objectives that we have chosen result directly from those meetings. All segments of the industry recognize sow productivity and nutrition as an extremely important factor affecting profitability in swine production systems. Although progress has been made in sow nutrition in the last 30 years, there is still a dearth of information relative to specific nutrient requirements of sows during gestation and lactation, especially the high milk-producing sows used today. Further research is greatly needed to completely define the levels of various nutrients necessary for optimizing reproduction and lactation, and for minimizing nutrient excretion.
Importance of the work:
It is extremely important to conduct research to provide solutions to potential sow nutrition and production problems and the impact that concentrated production systems have on the environment. Social restrictions and governmental regulations place extreme pressures on our production systems. Solutions to these issues must be resolved so that swine production in the South, an extremely important component of agricultural productivity, will remain, and that it will continue to be an economically viable opportunity for our work force.
Technical feasibility of the research: The original Southern Multi-State Research Group (S-145) and the current group (S-288) have made significant contributions in obtaining new knowledge and creating a better understanding of the nutritional needs of sows to improve reproductive efficiency. This Technical Committee has used the approach of (1) defining high priority research areas, (2) developing common protocols that are rigidly followed by all participating stations, (3) pooling the data, (4) drawing conclusions, and (5) publishing the pooled results in scientific journals. Since its inception, the Committee has published 13 refereed publications, 1 conference proceedings, and 17 abstracts. These publications are the direct result of the collaborative research effort of the Southern Multi-State Research Group. Also, in collaboration with the NCR-42 Committee, the Committee has published one book entitled Swine Nutrition and four book chapters. Over the last 20 years, participants in the Committee have clearly demonstrated that they can successfully collaborate in regional research. In addition, we meet with the NCR-42 Committee, which is an informational exchange group working on swine nutrition. We have opened our objectives to their participation.
Justification for a regional approach:
Sow research is well suited to a regional approach for two major reasons. First, in reproductive studies, large numbers of animals are required to generate meaningful data; individual experiment stations often do not have sufficient sow numbers to effectively conduct sow research. Second, pooled results from several experiments conducted with a common protocol but under different environments provides valuable information from which broad inferences can be drawn and more meaningful recommendations can be made. A further advantage of a regional approach is that the combined experience and expertise of several swine nutritionists can be focused on a few objectives. Also, a planned annual meeting provides opportunities to discuss new and old research findings.
Progress in sow nutrition and management research is hampered by the large variation among sows in the economically important reproductive traits (Aaron and Hays, 1991). In a summary of 2,346 farrowings in five herds, the coefficients of variation were 27% for total and live pigs farrowed and 32% for pigs weaned (Hays et al., 1969). In contrast, the coefficients of variation for growth rate and feed efficiency were 4 and 6%, respectively, for pens of growing and finishing pigs (Cromwell et al., 1984). The number of replications needed to detect a 10% difference in litter size at birth and at weaning, at an 80% success rate and a 5% probability level, is 114 and 161 sows per treatment, respectively. Thus, it is difficult for individual experiment stations to generate the number of observations needed to reach valid conclusions.
Goals and impacts of the current research:
The goals of this proposed project are to improve the reproductive performance of sows while reducing nutrient loss to the environment from urine and feces. This research will include a study to determine the concentration of nutrients currently excreted to the environment from urine and feces, and to investigate diets that increase the efficiency of production and reduce nutrient loss.
We plan to collect swine waste from sow production enterprises throughout the country to determine the nutrients that are lost to the environment from urine and feces. We plan to conduct research into particle size of diets for sows a direct suggestion from our stakeholders. Feed intake in sows is a factor that limits production efficiency and reducing dietary particle size may increase nutrient digestibility, which in turn will increase nutrients available to the sow and decrease nutrient losses to the environment. There is very limited research to date on particle size of diets for sows. We plan to evaluate the inclusion of crystalline amino acids into sow diets. Low crude protein, amino acid supplemented diets have been extensively evaluated in growing pigs and are used widely in the industry. These low crude protein diets effectively reduce nitrogen loss to the environment. The efficiency of crystalline amino acid use depends on the number of times pigs eat per day. Growing pigs are offered feed continuously, but sows are fed only one to three times daily, which may decrease their efficiency of utilization. There is very little research into the area of crystalline amino acid use in sow diets. We also plan to evaluate the use of carnitine in sow diets. Carnitine is a dietary additive that has been shown to increase sow productivity, but the data are limited, controversial, and inconsistent. A large-scale study is absolutely necessary to evaluate the efficacy of this intermediary metabolite.
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