S1081: Nutritional Systems for Swine to Increase Reproductive Efficiency
(Multistate Research Project)
S1081: Nutritional Systems for Swine to Increase Reproductive Efficiency
Duration: 10/01/2018 to 09/30/2023
Statement of Issues and Justification
Introduction: Swine production is globally distributed. The U.S. is the world's third-largest swine producing country behind China and the E.U. The U.S. has been the world’s largest or 2nd largest exporter of pork and pork products, with exports typically averaging over 20% of commercial pork production. Currently, U.S. pork production operations are heavily concentrated in the Midwest and eastern North Carolina. In 2016, about 118.3 million hogs were slaughtered in the U.S. for an estimated gross on-farm value of $18.9 billion (USDA, 2017). The average daily inventory was 72.9 million swine, of which 6.2 million were sows (USDA, 2018). Swine production is driven by the fact that pork continues to be one of the major high-quality sources of protein in human diets and, because of its flavor, pork is the meat of choice worldwide with an average per capita consumption of pork in the U.S. of 22.7 kg (USDA, 2018).
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 pork production in the Southern Region represents a significant portion of U.S. pork production, especially sow production. The most rapidly growing component of swine production in the Southern Region has been in sow farms producing feeder pigs that are shipped to the Midwest for finishing. This trend is attributed to favorable environmental conditions, the availability of labor, and interest in contract swine production in the Southern Region and to an availability of feedstuffs in the Midwest.
A primary factor affecting the profitability of swine production is sow productivity. Optimum nutrition of the sow is essential to maximize sow productivity and longevity. An ideal nutrition program should provide adequate nutrients to maximize sow productivity while minimizing excreted nutrients and feed costs. The continuing trend to increased litter size and intensive production schedules places biological demands on the sow that make high performance difficult to obtain and maintain. An increase in the number of pigs marketed/sow/year through improved sow nutrition would result in increased profitability by allocating fixed sow costs over more pigs. However, increased productivity can decrease longevity in the herd without proper nutrition. Studies indicate that a sow must complete at least 3 parities before reaching a positive net present value (the point when she has covered purchase price and feed costs; Stalder et al., 2000, 2003).
The research committee of the National Pork Board (NPB) has identified improvements in sow nutrition as an area needing further research. The current S-1061 committee meets yearly with members of the American Feed Industry Association, the NPB, and representatives from large feed companies to survey their assessment of research priorities. The specific research objectives that we have chosen result directly from those meetings. All segments of the industry recognize sow productivity and nutrition as extremely important factors affecting profitability in swine production systems. In fact, sow longevity is one of the key research areas identified by the NPB for the use of the commodity checkoff monies that are appropriated for research. 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 the prolific and 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 while minimizing nutrient excretion.
Importance of the work: It is extremely important to conduct research that provides solutions to potential sow nutrition and production problems and the impact that concentrated production systems have on the environment. Societal perspectives and governmental regulations place extreme pressures on our production systems. Solutions to these issues must be provided so that swine production, a critically 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-1061, previously S-1044, S-1012 and 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 after meeting with stakeholders, 2) developing common protocols that are followed by all participating stations [with certain aspects rigidly followed by all participants and other aspects having flexibility for individual stations], 3) pooling the data, 4) drawing conclusions, 5) publishing the pooled results as abstracts at professional meetings and in scientific journals and 6) dissemination of research results through extension programming, trade magazines, and direct producer contact. Since its inception, the Committee has published 18 refereed publications, 1 conference proceedings, 24 abstracts, and 1 extension publication. These publications are the direct result of the collaborative research efforts of the Southern Multi-State Research Group. Also, in collaboration with the NCCC-42 Committee, the Committee has published one book entitled "Swine Nutrition" (now in its second edition) and four book chapters. Committee members have been asked to speak at a number of producer and industry conferences to discuss research results. The S-1012 Committee was nominated by the Southern Region Departments Heads for the NASULGC award for Regional research. Over the last 20 years, participants in the Committee have clearly demonstrated that they can successfully collaborate in multi-state research. In addition, we meet annually with the NCCC-42 Committee, which is an informational exchange group working on swine nutrition. We have opened our objectives to their participation as well as participation by other institutions.
Justification for a multi-state approach: Sow research is well suited to a regional approach for three 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 for sow research. Progress in sow nutrition and management research is hampered by the large variation among sows in economically important reproductive traits (Aaron and Hays, 1991). In a summary of 7,925 farrowings in five herds, the coefficients of variation were 26-33% for total and live pigs farrowed and 36% for pigs weaned (Aaron and Hays, 2004). In contrast, the coefficients of variation for growth rate and feed efficiency were 5-8 and 4-7%, respectively, for pens of growing and finishing pigs. 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 99 and 193 sows per treatment, respectively. Thus, it is difficult for individual experiment stations to generate the number of observations needed to reach statistically significant conclusions. Second, pooled results from several experiments conducted with a common protocol but under different environments provide valuable information from which broad inferences can be drawn, and more robust recommendations can be made. A further advantage of a multi-state approach is that the combined experience and expertise of several swine nutritionists can be focused on a few high-priority objectives. Also, a planned annual meeting provides opportunities to discuss new and old research findings.
Goals and impacts of the current research: The primary goal of this proposed project is to improve the reproductive performance of sows while increasing their retention in the herd, enhancing offspring robustness, and minimizing sow nutrient excretion. This research will include studies to evaluate sow boron requirements, phytogenic feed additives, and gestational phase feeding to determine the effects on reproductive efficiency, including offspring growth, in an attempt to improve the economic return to swine producers. Boron is an inadequately-examined mineral in food animal production. Outcomes from the previous S-1061 project have begun to demonstrate the value of phytogenic feed additives such as essential oils in sow diets as a means to reduce the overall reliance of pork production on antibiotics (another current societal issue for animal production) through improved sow health and performance and subsequently enhanced offspring performance. Finally, phase feeding has long been used in post-wean diets as a means to more closely meet changing nutrient demands, limit excess protein excretion, and reduce diet costs but there is little data on this feeding strategy for sows. As sow health and productivity is increased by success in any of these objectives, there is potential improvement in enterprise profitability. The results also will demonstrate responsiveness to societally-important issues of waste management and the environment as well as concerns about antibiotic use in animal production.
Related, Current and Previous Work
Literature searches were made in the CSREES index, the CAB Index, the Index on Current Research in Pigs, and the Index of the Journal of Animal Science to locate past and current research in the three project areas.
Objective 1: Boron in sow diets: Although boron was accepted as an essential nutrient for plants as early as 1926 because it was necessary to complete the life cycle (Sommer and Lipman, 1926), a clearly defined biochemical function has not been identified (Nielsen, 2014). Similarly, the requirement of boron for animals is unclear. Before 1980, the thought was that boron was a unique element because it was essential for plants but not for higher-order animals. However, in 1981 it was reported that boron stimulated growth and partially prevented leg abnormalities present in vitamin D-deficient chicks (Hunt and Nielsen, 1981). Since then, evidence has been accumulating that suggests that boron is an essential nutrient for higher-order animals including humans. The evidence that boron deprivation can impair growth has been the basis for further research in several independent laboratories. Boron deprivation has been shown to reduce feed efficiency in weanling pigs (Armstrong et al., 2000) and growth in chicks (Bai and Hunt, 1996) and rats (Naghii and Samman, 1996).
Boron also appears to function in bone mineralization and structure. The addition of boron and other ultra-trace elements to a chick trace mineral premix increased tibial bone ash percentage and reduced the incidence of tibial dyschondroplasia (Edwards, 1987). Supplementing boron in natural ingredient and semipurified diets increased bone ash percentage in broiler chicks (Elliot and Edwards, 1992). Armstrong et al. (2000) observed that supplementation of 5 mg boron/kg diet to a semipurified basal diet increased the maximum bending moment of the femur; this group further found that long-term boron supplementation had beneficial effects on bone characteristics in gilts (Armstrong et al., 2002). These effects are consistent with other literature showing that boron supplementation increased tibial breaking load (Rossi et al., 1993) and increased shear fracture energy of the femur, tibia, and radius (Wilson and Ruszler, 1998) in chicks. Vertebral resistance to a crushing force has also been increased by boron supplementation in rats (Chapin et al., 1998). Brown et al. (1989) found that boron supplementation increased calcium and magnesium retention in lambs. Similarly, Small et al. (1997) found that dietary boron influences the metabolism of Ca, Mg, P, and Cu. Armstrong et al. (2000) also demonstrated a reduction in bone lipid percentage and plasma triglycerides with boron supplementation in pigs fed semipurified diets but not in pigs fed natural ingredient based diets. These studies demonstrate that boron supplementation has the potential to affect many bone characteristics but, even though soundness is one of the primary reasons for culling sows, the effect of boron supplementation on soundness and longevity in breeding swine has not been evaluated.
In addition to effects observed in various bone characteristics, boron has been linked to energy metabolism (Hunt, 1997), insulin sensitivity and the immune system (Hunt and Idso, 1999; Armstrong et al., 2001). Armstrong et al. (2001) demonstrated that boron decreased the inflammatory response to an intradermal injection of phytohemagglutinin in gilts. Dietary boron decreases peak pancreatic in situ insulin release in chicks and plasma insulin concentrations in rats regardless of vitamin D or Mg status (Bakken and Hunt, 2003). In these studies, boron supplementation (2 mg/kg diet) to rats fed a low-boron diet (0.2 mg/kg) reduced plasma insulin but did not change plasma glucose concentrations. Peak insulin release from isolated, perfused pancreata of boron-deprived chicks was almost 75% higher than that from pancreata of boron-supplemented chicks. (Bakken and Hunt, 2003). These findings suggest that boron may reduce the amount of insulin needed to maintain plasma glucose, a benefit that could be useful given the demonstration of Kemp et al. (1996) that sows can be gestationally diabetic in late gestation and that the glucose tolerance of pregnant sows is related to postnatal pig mortality.
Boron may also benefit reproductive characteristics. A deficiency of boron has resulted in impaired embryonic development in rats (Lanoue et al., 2000), and boron supplementation has stimulated growth and increased survivability of trout embryos (Eckhert, 1998). In studies using zebrafish (Dania rerio), it was found that boron was essential for completing the cleavage stage of embryonic development (Eckhert and Rowe, 1999). In still another species, Small et al. (1997) reported an association between poor conception and low serum boron concentrations in beef cattle. Armstrong et al., 2002, in a limited study involving only 8 gilts/treatment, evaluated the long-term effects of boron on reproductive characteristics and observed that supplementation tended to increase pig birth weight and reduce the number of dead embryos.
Thus, evidence from numerous laboratories using a variety of experimental models shows that boron is a beneficial bioactive element that affects metabolism and is necessary for completion of the life cycle in animals. Although evidence is very limited, studies in swine suggest that supplemental boron may affect reproductive performance, immune function and insulin sensitivity. We propose to evaluate the effect of long-term effects of supplemental boron on reproductive performance in breeding swine. In addition, effects on bone response measures and insulin sensitivity will be evaluated in sows and offspring.
Objective 2: Phytogenic feed additives and reproductive performance of sows: Public concern over the routine use of antibiotics led to the ban of antibiotics as a feed additive in the European Union (Wenk, 2003; Windisch et al., 2008; Janczyk et al., 2009) and also limitations by the new Veterinary Feed Directive (FDA, 2015) on use in livestock of antibiotics that are medically important to humans. Thus, it is important to explore new ways to improve and protect the health status of farm animals (Wenk, 2003; Windisch et al., 2008). Although that goal can be achieved by various means, such as maintaining good housing or climatic conditions (Wenk, 2003), some phytogenic feed additives can be added to the growing list of non-antibiotic growth promoters (Windisch et al., 2008) in attaining societal goals.
Phytogenic feed additives are a wide variety of plant-derived compounds that can be incorporated into diets to improve the productivity of animals (Windisch et al., 2008). Based on the origin and processing method, phytogenic compounds can be classified as herbs, spices, oleoresins, or essential oils (Windisch et al., 2008; Jacela et al., 2010). The actual content and/or concentration of active substances in those compounds can be very diverse depending on the type of plants, part of plants, and processing method. Essential oils are volatile, aromatic mixtures, consisting mainly of terpenes and phenylpropane derivatives, that are present in many plants (Janczyk et al., 2009). The composition of phytogenic feed additives are complex (e.g., most essential oils contain hundreds of substances that have been shown to exert various biological activities).
The primary function of essential oils is to protect the plant (e.g., against bacteria and parasites; Janczyk et al., 2009) as many essential oils have antimicrobial and strong antioxidative activities in vitro (Hammer et al., 1999; Dorman and Deans, 2000). Windisch et al. (2008) reviewed the effects of phytogenic compounds as a feed additive in pig and poultry diets that include their effects on antioxidative properties, palatability, antimicrobial activities and gut functions, and growth promotion. Recently, Zou et al. (2016) demonstrated that finishing pigs (72 to 100 kg of BW) fed a diet containing 25 mg/kg of oregano essential oils had increased expression of occludin and zonula occludens-1 and greater villus height in the jejunum, lower endotoxin levels in serum, lower population of Escherichia coli in the jejunum, ileum, and colon, and lower expression of inflammatory cytokines in the jejunum compared to control pigs. It is difficult to generalize mechanism(s) of action because of the many factors that can influence these responses; nevertheless, the broad array of benefits were clearly treatment (i.e., essential oil) related.
Low conception and farrowing rates and low survival rate of piglets are problems facing the swine industry (Maxwell et al., 1994). Considering the potential beneficial effects of phytogenic feed additives, it is not surprising that most studies have been conducted with weanling piglets, even though the antimicrobial effects of some additives may also have some positive impacts on the reproductive performance of sows. For instance, Amrik and Bilkei (2004) and Allan and Bilkei (2005) evaluated the effect of dietary oregano oil (500 mg/kg mixed with the dried leaf and flower of Origanum vulgare) fed from d 110 of gestation through lactation on reproductive performance of sows under commercial conditions in Europe. Oregano treated sows had lower annual sow mortality rate and culling rate, increased subsequent farrowing rate, and more live born piglets per sow compared with untreated sows (Amrik and Bilkei, 2004). Similarly, in the other study (Allan and Bilkei, 2005), sows fed oregano again had reduced annual sow mortality and culling rates, increased farrowing rate, increased number of live born piglets per sow, and reduced stillborn rate. While these results demonstrate potential, the experimental methodology had limitations. Because the research was conducted in commercial settings, alternate breeding groups of sows were assigned to the treatment diet rather than treatments being administered among contemporaries. In a more controlled study, Tan et al. (2015) reported that multiparous Large White sows fed 15 mg/kg of oregano essential oils (from 300 mg/kg of the oregano product) throughout gestation and lactation had greater piglet weight at birth (P = 0.04), litter and piglet weight at weaning (P < 0.05), and piglet ADG during lactation (P < 0.01). In addition, the oregano essential oil fed sows had a lower concentration of serum thiobarbituric acid reactive substances (TBARS; P < 0.05), which might suggest a reduced oxidative stress status of sows. More recently, Renken et al., (2017) reported that supplementation of oregano essential oils in sow diets for two complete reproductive cycles resulted in a tendency for fewer mummies (P = 0.07) and greater colostrum protein content (P = 0.06) compared to sows fed control diets. In contrast, Ariza-Nieto et al. (2011) observed that supplementation of oregano essential oils (250 mg/kg) during gestation and lactation did not affect colostrum or milk composition, nor the growth and immune response of suckling pigs.
In addition to some variability in the responses that have been observed in currently published literature, other questions remain relative to the utility of phytogenic feed additives in the U.S. in that the base cereal used in the U.S. would be corn compared to barley/wheat in Europe and other factors such as environment and management may differ between locations. Nevertheless, the results of the current studies indicate that dietary phytogenic feed additives may improve reproductive performance of sows, and some of the phytogenic feed additives may be an attractive alternative to antibiotics. Therefore, it would be of interest to explore the possible effect of various phytogenic feed additives during the breeding and lactation periods on the reproductive performance of sows.
Objective 3: Phase feeding of gestational sows: Pre-weaning mortality rate increased from 2008-2013 to an average of 17.3% and, while mortality rates have since remained stable, 17% is disconcerting - a point not lost on the National Pork Board who recently announced a $2 million call for proposals to investigate variables impacting mortality and identify potential solutions. Numerous factors influence pre-weaning death loss and strategies are routinely implemented to manage these risks including attended farrowing, dipping of navel cords, and cross-fostering (Reese et al., 2008). Strategies such as age segregation and maintaining a closed herd are also used to control disease exposure and enhance disease resistance. Despite routine use, pre-weaning mortality is still a concern, suggesting that improving piglet robustness at birth (i.e., a strong ability to withstand nutritional and disease pressure) can lessen the likelihood of pre-weaning death and thereby improve piglet survivability, allowing maximal benefit from advances in genetics and herd management.
Reducing piglet death loss has potential to indirectly affect environmental impact and sustainability of natural resources; more pigs marketed without an increase in the sow herd, sow feed and water inputs or manure outputs mean lower fixed cost and environmental impact per pig sold. Human, rodent, and pig models have demonstrated that deficient maternal protein supply in gestation increases the risk of growth-retarded offspring with less developed intestinal tracts, reduced post-weaning growth, greater visceral fat deposition, and suppressed immune response (Grace et al., 2011; Ference et al., 2014). In application to pork production, greater numbers of small and lightweight piglets with lower survivability and reduced post-natal growth increase production costs and reduce profitability.
Evidence in the late 1990’s and early 2000’s indicated that nutrient requirements increased in late gestation (Goodband et al., 2013). Practical implementation of revised sow phase feeding strategies is often limited by barn design (i.e., a single feed line); thus, “bump” feeding (i.e., increased feed allowance in late gestation) was implemented as a surrogate for phase feeding but not without a simultaneous increase in feed cost. Increasing evidence suggests that, within a single parity, the potential benefits may not offset the additional feed cost. As such, many sow barns have returned to constant feeding during gestation. The move to more group-housed gestation facilities incorporating electronic feeding systems in sow barns allows the use of multiple gestation diets and the question of the benefit of phase feeding is again at the forefront.
Few studies have assessed true phase feeding (i.e., change in the ratio of available nutrients by phase). Goncalves et al. (2016b) reported greater daily energy intake in late gestation increased piglet birth weight approximately 30g. Whereas, increased amino acid (AA) supply resulted in a 1.2% reduction in preweaning mortality in sows and 2% in gilts with no impact on birth weight. Further, litter birth weight CV was not affected by dietary AA supply indicating lower pre-wean mortality may have been due to greater piglet robustness rather than improved competitiveness due to size. Ampaire (2016) reported that the greatest impact of phase-feeding was observed in Parity 2. A larger proportion of heavy birthweight piglets (>2.0 kg) in phase-fed vs control or bump sows (11 vs 4 or 5%) and heavier piglets at weaning and 49d of age were observed. While the total sow sample set was a notable limitation, the data suggest 1) greater AA supply in late gestation improves offspring survivability and supports Goncalves et al. (2016b) and 2) assessment of biological markers and post-wean performance may better reflect the potential long-term impact of sow feeding regimen than birth weight or litter size. Additionally, Goodband et al. (2013) suggested that within a single gestation period average piglet weight is unlikely to be impacted because the sow has a dramatic capacity to compensate through catabolism of maternal nutrient stores, notwithstanding severe restrictions in energy intake. Further, the pilot study suggests single parity studies are insufficient to understand the implications of sow feeding regimen under practical conditions. Thus, an important limitation with much of the published data is that studies are conducted in a single reproductive cycle only and may not assess suckling piglet growth or post-wean performance. However, the gilt/sow is expected to remain productive over multiple reproductive cycles, and nutritional intake in any single reproductive cycle may impact performance in a subsequent reproductive cycle (Clowes et al., 2003). Therefore, it is necessary to explore the longer-term impact of phase feeding on reproductive performance with an emphasis on multi-parity studies and assessment of offspring robustness.
Accomplishments of the Previous Project: Due to other research commitments at the various participating stations (i.e., externally funded project or a graduate student project) exclusive use of the sows to contribute to the multi-state project was not possible. However, progress was made in all objectives, and there have been refereed publications as well as abstracts resulting from the project in all objective areas. With regard to the specific objectives for the S-1061 project (2013-2018), the following has occurred:
- To determine the effect of copper supplementation on the reproductive performance of sows: This was the highest rated objective in the 2008-2013 project, but there were not enough participants ready to begin this project because of particular methodological needs. Initiation of the objective was deferred to the current 2013-2018 project. Three stations contributed sows to the project (University of Kentucky, Virginia Tech, and the University of Arkansas). The project has been completed and one D. dissertation and two abstracts currently published from the project. Pooled data is currently being analyzed that will result in more abstracts and refereed manuscripts. There are at least two more manuscripts planned. Further, because of results observed related to differing performance in the nursery from the offspring of the sows on different copper treatments, a further joint study between two participants is in progress to follow those unexpected effects, and that should result in another publication.
- Essential oils and reproductive performance of sows: This objective was the last to be initiated. A total of 3 stations (University of Kentucky, South Dakota State University, and the University of Georgia) have begun generating data. Three abstracts and one extension article have been published. Additional data continues to be generated with a phytogenic feed additive and is the reason that this objective will be carried over into the new project.
- To determine the effect of organic minerals on sow productivity and longevity: This objective had substantial data contributed by 3 participating stations (University of Arkansas, Virginia Tech, and Southern Illinois University). One abstract has been presented, and a manuscript is currently in development.
To determine the effects of boron supplementation on sow reproductive performance.
To determine the effect of phytogenic feed additives on sow reproductive performance.
To determine the effect of altered gestational feeding of sows on sow productivity and longevity as well as offspring robustness.
General Procedures: These procedures will be followed for all objectives, except where specifically indicated within the discussion of each objective.
- Corn-soybean meal diets of similar formulation constraints will be fed in gestation (from breeding until sows enter the farrowing house at approximately d 110 of gestation) and lactation (from approximately d 110 of gestation through weaning).
- The coordinator of each objective area will procure test products, as well as a vitamin and trace mineral premix that will be used at all participating locations. The coordinator will maintain inventory and will distribute to participating locations as needed by the number of sows assigned at each location.
- Gilts or sows may be started on the studies but sows should be no older than second or third parity. Females will be allotted to dietary treatment within 10 days postbreeding for gestation treatments and upon entering the farrowing house at approximately d 110 of gestation for lactation treatments. In all cases, attention will be given to balancing the allotment relative to parity, weight, and genetic background of the available females. Females completing at least one parity will be considered in the statistical analysis of the data; however, stations will be encouraged to retain each female in a study for at least 2 parities.
- During gestation, sow daily feed allotment will be according to standard practices taking into account environment and body condition.
- Sows will be allotted to dietary treatment and will remain assigned to this diet for all subsequent reproductive cycles. Feed consumption will be recorded from farrowing to weaning.
- During lactation, sows will be offered feed at least 2 to 3 times per day and fed to appetite.
- General observations recorded include: sow/gilt body weight at breeding, when entering the farrowing room (i.e. d110 of gestation), within 24h postpartum and weaning, number and litter weight of pigs at birth (live and total), after cross-fostering, and at weaning, and piglet body weight at birth and weaning.
- Conception, farrowing and culling rates will be recorded along with reasons for culling. Cross-fostering should be kept to a minimum and within treatment; it must be done by day 3 of age. Litter size should be standardized to 10-12 pigs per sow by day 3 post-farrowing when a part of a particular objective.
- After weaning all sows will be checked for estrus with mature boars at least once per day, preferably twice, and the number of days to first estrus recorded.
- Representative feed samples will be collected from each feed mixing, pooled by diet and farrowing group, and a composite sample submitted for analysis of DM, CP, Ca and P. Samples will also be analyzed for the nutrient(s) or compounds investigated in the project objective so that verification of proper incorporation of dietary treatments can be made and that indigenous levels of various nutrients can be established from the unsupplemented diet.
- All data will be sent to the objective coordinator. The objective coordinator will be responsible for dietary assays as well as pooling and verifying the experimental data, summarizing the data and conducting statistical analysis, and writing publications related to the data. Statistical models must include (at a minimum) Station, Parity, Diet, and Diet by Parity and Station by Diet interaction terms. Appropriate covariates will be used when needed.
Specific Procedures for each Objective:
To determine the effect of boron supplementation on the reproductive performance of sows: Coordinator: C. Maxwell. Stations which have indicated that they plan to participate in this objective are: AR, GA, KY, and VA.
- Boron as sodium borate pentahydrate will be fed to sows at 0, 5, and 25 ppm of supplemental boron. Dietary treatments will be fed continuously during both gestation and lactation.
- Stations that are able will be encouraged to collect blood samples at the end of the gestation and lactation phases to determine boron status in the sows.
- Glucose tolerance and insulin sensitivity of sows will be assessed in late gestation (between d 80-100) as described by Lindemann et al. (1995) at stations that can do so. Serum glucose, insulin, and insulin:glucose ratio will be measured and calculated.
- In selected weaning groups, a representative sample of weaned piglets from sows on all treatments will be sacrificed for tissue mineral content and various bone measurements (e.g., breaking strength, ash, and Ca/P content). Representative sows will also be sacrificed for similar tissue and bone measurements.
To determine the effect of phytogenic feed additives on the reproductive performance of sows: Coordinator: M. D. Lindemann. Stations that have indicated that they plan on participating in this objective are: AL, AR, GA, KY, NC, SDSU, and VA.
- Treatments for assessment may include feeding a diet containing: 1) no antibiotic or phytogenic feed additive [negative control], 2) essential oil at one or more levels (Chios Gum Mastic as the initial treatment) during breeding and lactation (e.g., from about 1 wk before breeding until 15 d after breeding and from d 110 of gestation until 15 d after the postweaning rebreeding). The decisions about which phytogenic feed additives (or combinations) to assess will be made by the Committee based on the availability of commercial products.
- Litters should be cross-fostered so that all sows are nursing 10 pigs 24-36 hours post-partum.
- Early (day 6-10) and late (day 14-18) milk samples will be collected for analysis (total solids, fat, lactose, and protein). Blood samples at the same time points should be taken by stations that are able for assessment of TBARS or another measure of oxidative stress.
- Fecal samples will be collected at stations that can assess fecal DM (a measure of constipation) upon entrance to the farrowing house, and early (day 6-10) and late (day 14-18) lactation.
To determine the effect of altered gestational feeding of sows on sow productivity and longevity: Coordinator: C. Levesque. Stations that have indicated that they plan on participating in this objective are: AL, AR, GA, NCSU, and SDSU.
- Sows will be assigned to one of at least 2 gestational feeding programs that include a control (constant intake from breeding to d110 of gestation or increased feed allotment in late gestation), and an altered phase feeding program (focused on altered lysine:energy ratio in early and late gestation). Late gestation may be defined as beginning at d 90 – 100 of gestation. Sows will receive a common lactation diet from d110 – weaning and return to previous gestational feeding program in each subsequent parity. Where possible, groups of like parity will be used to begin to identify parity-specific responses.
- Where possible, stations will be encouraged to collect additional data, including: sow blood samples at the end of the gestation and lactation phases for the determination of serum urea nitrogen, cord blood at birth from at least 6 piglets/litter for assessment of cortisol content, offspring post-wean performance, as well as colostrum and milk samples for nutrient composition and immunoglobulin content.
Measurement of Progress and Results
- For all objectives, evaluation of reproductive performance will be based on changes in sow body weight in gestation and lactation, litter size at birth and weaning, offspring growth (suckling and post-wean), days to estrus in subsequent parities, and lactation feed consumption.
- For Objective 1 (boron): the impact of supplementation on selected soft tissues and bone measures (bone breaking strength and ash content; Ca, P, Fe, Zn, Cu, and Mn) will also be assessed at two stations. Blood samples for insulin sensitivity will be taken by at least one station.
- For Objective 2 (phytogenic feed additives): the impact of phytogenic feed additives on total tract digestibility of dry matter, energy, and protein, as well as fecal consistency (as an indicator of constipation) will be evaluated. The influence of dietary treatment on milk nutrient composition as a contributor to potentially improved offspring performance will be assessed.
- For Objective 3 (control vs phase feeding): cord cortisol content will provide an indicator of enhanced offspring robustness as influenced by gestational feeding program. Similarly, milk nutrient composition and colostral immunoglobulin content are indicators of potential for improved offspring performance.
Outcomes or Projected Impacts
- Across all objectives, we will be able to determine if sow reproductive efficiency is affected when sows are administered one of the respective feeding strategies or alterations. Where results are positive, increases in sow productivity will increase producer income. An agricultural economist will be engaged to provide an assessment of the economic feasibility of the application of this research.
- Each project has potential to not only improve sow reproductive performance but also enhance offspring performance. Additionally, this project will contribute a greater understanding of the impact of sow feeding strategies over multiple parities - knowledge that is critical to sow wellbeing and which will reduce sow culling, thereby improving long-term success and sustainability of pork production.
- While it is difficult to predict an economic impact of these strategies, a 1% reduction in sow mortality equates to 62,000 sows annually, and a 1% reduction of pre-wean mortality would result in > 1 million additional market hogs without an increase in litter size of sow herd, both of these representing a substantial economic impact.
Milestones(0):There are no time-linked accomplishments needed before any of the objectives can be addressed.
Projected ParticipationView Appendix E: Participation
Data from each objective will be published first in abstract form by the coordinator of the objective, and he/she will present the data orally or in poster form at a national or regional scientific conference. Next, a manuscript will be prepared and submitted to a refereed journal, probably the Journal of Animal Science. Each participant on the objectives may choose to publish their contribution to the objective in producer field days, university publications, or in a graduate student's thesis or dissertation. Also, some members of the committee hold extension appointments, and all members of the committee interact with their extension colleagues or participate in extension functions. Results will also be published in trade magazine Research Reports with the specific note that the results are from a multi-state research project.
The Multi-state research committee includes the regional Administrative Advisor (nonvoting); a technical representative of each cooperating experiment station, appointed by the respective Director; and a non-voting, consulting member representing CSREES. The Committee will elect a Chair, Vice-Chair, and Recorder. The Recorder position will be elected each year; the Vice-Chair will move into the position of Chair, the Recorder will move to the position of Vice-Chair. Administrative guidance will be provided by an assigned Administrative Advisor and a CSREES Representative.
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