Gilt Development Research Articles

263 Review of Current Nutrition Knowledge and Practices for Gilt Development

Abstract Nutrition for replacement gilts aims to support the development of prepubertal gilts towards their physiological maturity in terms of body weight, body tissue composition, structural soundness, and reproductive development. A key concept of gilt nutrition for lifetime productivity is to maintain a positive prepubertal growth rate and reach a target body weight of 115 to 140 kg at puberty. The application of this concept commonly presents a challenge with fast-growing and highly efficient contemporary gilt lines, particularly considering the proportion of gilts exceeding the target body weight at puberty and the negative impacts of overweight gilts on lactational performance, structural soundness, and longevity. Thus, nutritional decisions regarding dietary levels of energy, amino acids, and minerals in the pre- and peripubertal stage can be conflicting. Typically, gilts are fed ad libitum with moderate levels of energy and amino acids because restrictions below the requirements can have a negative effect on puberty onset. In addition, a high plane of nutrition is offered after the pubertal estrus to set ovulation rate for breeding at the next estrus. Moreover, gilts are fed levels of dietary calcium, phosphorus, and trace minerals above the requirements to improve bone mineral density in preparation for fetal development and lactation mobilization. Although these nutritional practices improve gilt performance, they also typically increase weight gain. Thus, there is a need to review nutritional strategies to manage body weight of replacement gilts while attaining optimum reproductive success and lifetime productivity.

Modelling the transmission and vaccination strategy for porcine reproductive and respiratory syndrome virus.

Many aspects of the porcine reproductive and respiratory syndrome virus (PRRSV) between-farm transmission dynamics have been investigated, but uncertainty remains about the significance of farm type and different transmission routes on PRRSV spread. We developed a stochastic epidemiological model calibrated on weekly PRRSV outbreaks accounting for the population dynamics in different pig production phases, breeding herds, gilt development units, nurseries and finisher farms, of three hog producer companies. Our model accounted for indirect contacts by the close distance between farms (local transmission), between-farm animal movements (pig flow) and reinfection of sow farms (re-break). The fitted model was used to examine the effectiveness of vaccination strategies and complementary interventions such as enhanced PRRSV detection and vaccination delays and forecast the spatial distribution of PRRSV outbreak. The results of our analysis indicated that for sow farms, 59% of the simulated infections were related to local transmission (e.g. airborne, feed deliveries, shared equipment) whereas 36% and 5% were related to animal movements and re-break, respectively. For nursery farms, 80% of infections were related to animal movements and 20% to local transmission; while at finisher farms, it was split between local transmission and animal movements. Assuming that the current vaccines are 1% effective in mitigating between-farm PRRSV transmission, weaned pigs vaccination would reduce the incidence of PRRSV outbreaks by 3%, indeed under any scenario vaccination alone was insufficient for completely controlling PRRSV spread. Our results also showed that intensifying PRRSV detection and/or vaccination pigs at placement increased the effectiveness of all simulated vaccination strategies. Our model reproduced the incidence and PRRSV spatial distribution; therefore, this model could also be used to map current and future farms at-risk. Finally, this model could be a useful tool for veterinarians, allowing them to identify the effect of transmission routes and different vaccination interventions to control PRRSV spread.

The between-farm transmission dynamics of porcine epidemic diarrhoea virus: A short-term forecast modelling comparison and the effectiveness of control strategies.

A limited understanding of the transmission dynamics of swine disease is a significant obstacle to prevent and control disease spread. Therefore, understanding between-farm transmission dynamics is crucial to developing disease forecasting systems to predict outbreaks that would allow the swine industry to tailor control strategies. Our objective was to forecast weekly porcine epidemic diarrhoea virus (PEDV) outbreaks by generating maps to identify current and future PEDV high-risk areas, and simulating the impact of control measures. Three epidemiological transmission models were developed and compared: a novel epidemiological modelling framework was developed specifically to model disease spread in swine populations, PigSpread, and two models built on previously developed ecosystems, SimInf (a stochastic disease spread simulations) and PoPS (Pest or Pathogen Spread). The models were calibrated on true weekly PEDV outbreaks from three spatially related swine production companies. Prediction accuracy across models was compared using the receiver operating characteristic area under the curve (AUC). Model outputs had a general agreement with observed outbreaks throughout the study period. PoPS had an AUC of 0.80, followed by PigSpread with 0.71, and SimInf had the lowest at 0.59. Our analysis estimates that the combined strategies of herd closure, controlled exposure of gilts to live viruses (feedback) and on-farm biosecurity reinforcement reduced the number of outbreaks. On average, 76% to 89% reduction was seen in sow farms, while in gilt development units (GDU) was between 33% to 61% when deployed to sow and GDU farms located in probabilistic high-risk areas. Our multi-model forecasting approach can be used to prioritize surveillance and intervention strategies for PEDV and other diseases potentially leading to more resilient and healthier pig production systems.

Salmonella Infection in Nursery Piglets and Its Role in the Spread of Salmonellosis to Further Production Periods.

Few studies have focused on assessing Salmonella infection in the nursery and its role in further pig production periods. Mesenteric lymph nodes, intestinal content, and meat juice from 389 6-week-old male piglets intended for human consumption from five breeding farms and 191 pooled floor fecal samples from gilt development units (GDU) from the same farms were analyzed to estimate and characterize (by pulsed-field gel electrophoresis and antimicrobial resistance analyses) Salmonella infection. The prevalence of infection and shedding among piglets was 36.5% and 37.3%, respectively, shedding being significantly associated with infection (Odds Ratio = 12.7; CI 7.3–22.0). Salmonella Rissen; S. 4,[5],12:i:-; and S. Derby were the most common serotypes. A low level of Salmonella-specific maternal antibodies at the beginning of the nursery period suggested it was a period of high risk of infection. Resistance to 3rd- and 4th-generation cephalosporins was detected in piglet isolates although the piglets never received antibiotics, indicating they could be vectors of antimicrobial resistance. The same Salmonella clones were detected in piglet and GDU isolates, suggesting that infected piglets play a significant role in the infection of gilts and consequently of finishing pigs in the case of production farms. The control of Salmonella infection in nursery piglets may decrease the risk of abattoir and carcass contamination.

PSII-18 Dietary Strategy for Gilt Development

Abstract The objective was to determine a dietary strategy for gilt development that would improve reproductive performance. One thousand eighty-three gilts (DNA) were blocked by weight (average initial weight = 27.5 ± 4.8 kg) and allocated to one of four dietary treatments (267-273 gilts per treatment). Treatments included: 1) standard grower/finisher (SGF) diet; 2) maximize bone growth (MB) diet with increased available P and Ca; 3) maximize growth (MG) diet with increased energy and AA levels, or 4) maximize both bone and growth (MBG) diet. Each treatment had five phases with all gilts fed a common gestation diet after insemination. At 20 weeks of age, gilts fed MG and MBG diets were heavier (P < 0.05) than gilts fed other diets. Gilts fed the MG diet were heavier (116.9 kg; P < 0.05) at 23 weeks (start of boar exposure) than gilts fed other diets (SGF, 112 kg; MB, 110.3 kg; MBG, 114.6 kg). Gilts fed the MG diet were heavier (143.8 kg; P < 0.05) at mating (29 weeks of age) than gilts fed other diets (SGF, 139.0 kg; MB, 136.8 kg; MBG, 139.6 kg). Upon entering farrowing stalls, gilts fed the MG diet continued to be heavier (P < 0.05). More gilts farrowed (P < 0.05) when fed the MG diet (MG, 89.8%; MBG, 86.8%; MB, 82.2%; SGF, 81.9%). Dietary treatment had no impact on number of pigs born alive per litter, total pigs born per litter, or piglet birth and weaning weights. There was a tendency (P < 0.10) for gilts to remain in the sow herd to farrow their second litter when fed either the MG or MBG diet. Overall, feeding higher energy and AA levels to maximize growth increased gilt development weights, improved the number of gilts that farrowed, and tended to increase sow retention.

244 The effect of a high-fiber feeding program for replacement gilts on body weight and composition at breeding

Abstract Sixty-three gilts were recruited at 90 days of age to evaluate the effects of a high-fiber gilt development feeding program on body weight and composition at breeding. Gilts (initial BW 50.9 ± 0.9 kg) were housed individually and randomly attributed to one of four feeding programs: [1] commercial diet fed ad libitum (CON), [2] commercial diet fed 10%, or [3] 20% below ad libitum, and [4] a high-fiber diet fed ad libitum (25% more fiber than the commercial diet and energy density reduced by 5%; FIB). Gilts received the feeding program between 90 days of age and breeding at ~190 days of age. Body weight and feed disappearance were determined weekly. Backfat depth was determined at 90, 145 (puberty), 160, and 190 (breeding) days of age. Over the entire experimental period, CON and FIB gilts had greater ADFI (mean of 3.50 ±0.07 kg) compared to 10% (2.95 ± 0.06 kg) and 20% gilts (2.70 ± 0.07kg; P < 0.05). The FIB feeding program reduced total energy and lysine intakes to amounts similar to 10%; both intakes were less than CON but greater than 20% gilts (P < 0.05). The ADG of FIB was less between days 145 (puberty) and 160 of age compared to CON gilts (0.86 vs. 1.09 ± 0.07 kg; P < 0.05). At breeding, FIB and 10% weighed less (146.5 ± 1.6 kg) than CON (152.7 ± 1.6 kg) and more than 20% gilts (138.7 ± 1.5 kg; P < 0.05). The FIB had less backfat than CON at breeding (14.9 vs. 16.7 ± 0.5 mm; P < 0.05), but did not differ from 10% or 20% gilts. In conclusion, the FIB feeding program limited energy intake, growth, and body fatness of gilts at breeding, even though gilts were offered feed ad libitum. Therefore, high-fiber feeding programs could be a practical means to control growth rates of developing gilts in commercial scenarios.

Efficacy and Safety of Venetoclax in Combination with Gilteritinib for Relapsed/Refractory FLT3-Mutated Acute Myeloid Leukemia in the Expansion Cohort of a Phase 1b Study

Efficacy and Safety of Venetoclax in Combination with Gilteritinib for Relapsed/Refractory FLT3-Mutated Acute Myeloid Leukemia in the Expansion Cohort of a Phase 1b Study

Assessment of nebulization technology for gilt exposure to Mycoplasma hyopneumoniae as an acclimation strategy

Objective: This study assessed the efficacy of nebulization (NEB), also known as fogging, to expose gilts to Mycoplasma hyopneumoniae under field conditions as a potential acclimation strategy. Materials and methods: Phase I consisted of 448 M hyopneumoniae-free gilts from four different batches of a gilt development unit (GDU). On study day 0, batches 1 and 2 were exposed to M hyopneumoniae-positive lung homogenate via intratracheal (IT) route and were used as reference for batches 3 and 4, which were exposed using a mechanical fogger. Tracheobronchial swabs (TBS) were collected at 2 and 4 weeks post exposure (D14 and D28, respectively) and infection success was assessed by real-time polymerase chain reaction of pooled samples. In phase II, 1160 gilts from the same GDU belonging to three different batches (5 to 7) were exposed to M hyopneumoniae via NEB, and TBS were collected at D14. Results: In phase I, no statistically significant differences were observed between IT and NEB exposure in proportion of positives and mean cycle threshold values of TBS pooled samples at any time point (D14 and D28). In phase II, TBS pooled samples from all batches were positive for M hyopneumoniae at D14. Implications: Nebulization of lung homogenate positive for M hyopneumoniae resulted in infection of commercial gilts with this pathogen. Therefore, the use of NEB may be a reliable M hyopneumoniae exposure method under field conditions. The information generated in this investigation broadens the understanding of this technology as an acclimation strategy.

Dietary lysine-to-energy ratios for managing growth and pubertal development in replacement gilts

Our objectives were to determine growth rates, body composition, and pubertal development in replacement gilts fed diets with different ratios of standardized ileal digestible (SID) lysine to ME. Diets with low, medium, and high ratios of SID lysine to ME (grower: 2.3, 2.6, and 2.8; finisher; 1.7, 1.9, and 2.1 g/Mcal) were fed from 100 to 200 d of age, after which gilts were moved from the gilt development unit to sow farms. Boar exposure and estrus detection began at 160 d of age and continued until first detected estrus. Estimates of BW and body composition were determined at 100, 142, 160, and 200 d of age and at puberty. Body weights and growth rates were reduced (P < 0.05) as dietary SID lysine–to–ME ratio decreased. Greater SID lysine–to–ME ratios increased the number of gilts that exhibited estrus upon boar exposure, increased the number of gilts with a spontaneous first estrus, reduced the number of gilts requiring P.G.600 (Merck Animal Health, Kenilworth, NJ), and decreased age at first estrus (P < 0.05). Slower growing gilts that weighed less with less backfat were more likely to require P.G.600 to induce puberty (P < 0.05). Reducing SID lysine–to–ME ratios in gilt diets can increase the number of gilts within optimal BW range at first estrus, but overall pubertal development is delayed if ratios are reduced below 2.8 and 2.1 g of SID lysine to megacalorie of ME in grower and finisher diets, respectively.

Calculating breeding herd feed usage and cost in commercial production systems

The objective of this paper is to describe a production tool for swine producers, veterinarians, and nutritionists to benchmark feed usage and feed cost within gestation, lactation, and gilt development phases of a production system. The model was developed using Microsoft Excel (version 16.0.11328.20438) and includes key variables within the breeding herd affecting feed usage. Data from a commercial production system was used to determine model accuracy as well as demonstrate its use. The results from this production tool provide estimates for feed usage and feed cost within each subpopulation of animals in the breeding herd.

Network analysis of swine movements in a multi-site pig production system in Iowa, USA

Pig production in the United States is based on multi-site systems in which pigs are transported between farms after the conclusion of each particular production phase. Although ground transportation is a critical component of the pork supply chain, it might constitute a potential route of infectious disease dissemination. Here, we used a time series network analysis to: (1) describe pig movement flow in a multi-site production system in Iowa, USA, (2) conduct percolation analysis to investigate network robustness to interventions for diseases with different transmissibility, and (3) assess the potential impact of each farm type on disease dissemination across the system. Movement reports from 2014–2016 were provided by Iowa Select Farms, Iowa Fall, IA. A total of 76,566 shipments across sites was analyzed, and time series network analyses with temporal resolution of 1, 3, 6, 12, and 36 months were considered. The general topological properties of networks with resolution of 1, 3, 6, and 12 months were compared with the whole period static network (36 months) and included the following features: number of nodes and edges, degree assortativity, density, average path length, diameter, clustering coefficients, giant strongly connected component, giant weakly connected component, giant in component, and giant out component. Small-world and scale-free topologies, centrality parameters, and percolation analysis were investigated for the networks with 1-month window. Networks’ robustness to interventions was assessed by using the Basic Reproduction Number (R0). Centrality parameters indicate that gilt development units (GDU), nursery, and sow farms have more central role in the pig production hierarchical structure. Therefore, they are potentially major factors of introduction and spread of diseases over the system. Wean-to-finishing and finishing sites displayed high in-degree values, indicating that they are more susceptible to be infected. Percolation analysis combined with general properties (i.e. heavy-tailed distributions and degree disassortative) suggested that networks with 1-month time resolution were highly responsive to interventions. Furthermore, the characteristics of a disease should have strong implications in the biosecurity practices across production sites. For instance, biosecurity practices should be focused on sow farms for highly contagious disease (e.g., foot and mouth disease), while it should target nursery sites in the case of a less contagious diseases (i.e. mycobacterial infections). Understanding the patterns of swine movements is crucial for the swine industry decision-making in the case of an epidemic, as well as to design cost-effective approaches to monitor, prevent, control and eradicate infectious diseases in multi-site systems.

Reducing life cycle fossil energy and greenhouse gas emissions for Midwest swine production systems

Abstract Over the last 30 years, the US swine industry has concentrated more animals on fewer farms in the Midwest US corn-belt region to more efficiently produce pork. At the same time, the food industry is beginning to be called upon by consumers to supply products with lower environmental footprints. Swine producers have opportunities to decrease the environmental impacts of their products, but need to know where the most beneficial changes can be incorporated. This study examined the fossil energy consumption and global warming potential (GWP) emissions at Midwestern swine farms using life cycle assessment methodology. Cradle-to-gate swine production scenarios were modeled using a combination of farm productivity survey data and on-farm energy monitoring, with an emphasis on activities related to swine production facilities and their operations. Fossil energy use totaled 10.6 MJ per kg of hog live weight (LW) in the average commercial scenario, 67% of which was used in the grow-finish stage, 11% in the farrowing stage, 12% in the nursery stage, 6% in gestation and 4% in gilt development. Average commercial scenario GWP emissions were 2.41 kg CO2 equiv. per kg hog LW, with 75% emitted during the grow-finish phase, 6% in farrowing, 9% in the nursery phase, 7% in gestation, and 2% in gilt development. Fossil energy required and GWP emissions for facilities and operations were 3.36 MJ and 0.15 kg CO2 per kg hog LW, respectively, and accounted for 32% of the system fossil energy and 6% of emissions in the average commercial scenario. Though fossil energy and GWP impacts resulting from swine production facilities and operations are smaller than those for feed ingredients and manure management, swine producers can directly influence these impacts through management. Heating, cooling, and ventilation are prime areas in facilities and operations where energy efficiency technology could reduce impacts. Lowering facility and operation energy inputs by 30% would decrease fossil fuel use in the system by 10% and slightly decrease GWP emissions. In the future, substituting renewable energy for fossil-based energy and using other efficiency technologies for current electricity and heating fuel needs may be able to eliminate the fossil energy needed for swine facilities and production operations.

351 Neonatal birth weight effects on gilt development growth and first parity reproductive efficiency

Abstract There has been a great deal of interest in gilt development characteristics that predict gilt growth and reproductive traits and which could be measured and manipulated early in the gilt’s lifetime. The objective of the study was to determine neonatal birth weight effects on gilt development growth performance and parity 1 sow reproductive performance traits. Data were collected from 1,052 litters housed at Circle 4 Farms, Milford, UT. A total of 2,960 crossbred Large White x Landrace maternal line gilts entered the research gilt development unit. Gilts were categorized by their individual neonatal birth weight into 3 groups Group I (≤ 1.1 kg; n = 772), Group II (1.2 to 1.5 kg; n = 1,356), and Group III (≥ 1.6 kg; n = 832). Growth and reproductive trait least square means (±SE) for each birth weight group were analyzed and compared among birth weight groups using PROC GLM. Fixed effects in the model included birth weight, farm, and development diet with the random effect of pen within a room. Neonatal birth weight group was a significant (P &lt; 0.05) source of variation for gilt growth in development, number born alive, and litter birth weight at first parity. Gilts from the largest birth weight group had significantly (P &lt; 0.05) larger BW at 100 (45.1 ± 0.3 kg), and BW 200 days (125.7 ± 0.7 kg), faster average daily gain (0.81 ± 0.005 kg), larger BW at puberty (137.7 ± 0.8 kg), larger BW at farrowing (201.1 ± 1.2 kg), larger BW at post-weaning (195.0 ± 1.0 kg), larger number born alive (11.8 ± 0.1), larger litter birth weights (18.2 ± 0.2 kg). The largest birth weight group tended (P &gt; 0.05) to wean more pigs (9.0 ± 0.2) and have greater litter weaning weights (48.8 ± 1.04 kg) at first parity when compared to gilts from the other two birth weight groups. Improving neonatal birth weight will improve gilt development and productivity through first parity.

353 Optimal dietary lysine for growth development of gilts until first parity

Abstract Unacceptable sow longevity in modern production systems has placed nutritional programs for developing gilts into question. Nutritional programs are well defined for terminal pigs, but not for developing gilts. To achieve breeding targets and allow gilts to meet their maternal genetic potential for lifetime productivity, the optimum lysine requirement for developing gilts should be well understood. The National Pork Board Animal Science Committee commissioned trials to determine the optimum lysine levels for developing gilts in U.S. pig production systems. An experiment was conducted to challenge proposed dietary lysine concentration for optimum growth rate during gilt development. A total of 2,960 growing crossbred gilts were fed three grower-finisher diets, formulated to provide low lysine (0.68 and 0.52% SID lysine), medium lysine (0.79 and 0.60% SID lysine), and high lysine (0.90 and 0.68% SID lysine) levels and fed to developing gilts starting from 142 to 200 d of age. Gilts fed the high lysine dietary treatment had significantly increased body weight (BW), flank-to-flank length, backfat thickness (BF), loin depth (LD), average daily gain, and fat-to-lean ratio (P &lt; 0.05). Moreover, gilts fed the high lysine treatment during development phase had greater BW (202.4 ± 1.2 kg), BF (14.8 ± 0.2 mm), and LD (5.4 ± 0.5 cm) at first farrowing and BF (15.1 ± 0.2 mm) at weaning when compared with gilts fed the medium and low lysine treatments (P &lt; 0.05). Litter birth weight (17.4 ± 0.3 kg), number weaned (9.0 ± 0.2), and litter weaning weight (46.6 ± 0.9 kg) from the gilts fed the high lysine sow treatment were greater when compared with performance from gilts fed the medium and low treatments (P &lt; 0.05). Gilt development diets containing 2.79 g and 2.08 g SID lysine per MCal ME (high lysine grower and finisher diets, respectively) allowed gilts to achieve good growth and first parity reproductive performance.

352 Associations between day one piglet serum immunocrit ratio and subsequent growth during gilt development

Abstract Colostrum intake affects gut development in the neonatal piglet. The pig’s subsequent growth performance and viability may be affected by colostrum intake. Immunoglobulin uptake can be effectively estimated from the piglet’s immunocrit ratio (IR). The objective of this study was to determine the association between IR and growth performance from weaning to 200 days. Associations between serum IR measures and subsequent growth performance such as body weight, backfat thickness, caliper reading, and flank-to-flank distance at weaning (WW), 100, 142, 160, and 200 days, average daily gain (ADG) between weaning to 100 days (ADG1), and ADG between 100 to 200 days (ADG2) were evaluated. The IR measures were collected from 2,715 female piglets on Day 1 at Circle 4 Farms, Milford, UT and measured by USMARC. The IR evaluation was divided into 5 groups: lowest (0.05 &lt; IC; n = 90), low (0.05 ≤ IC &lt; 0.1; n = 362), medium (0.1 ≤ IC &lt; 0.15; n = 1,314), high (0.15 ≤ IC &lt; 0.2; n = 949), and highest (IC ≥ 0.2; n = 141), respectively. Weaning weight, subsequent growth performance, and ADG least square mean for each IR category were analyzed using PROC GLM and PDIFF option for mean comparisons. Fixed effects for post-weaning growth traits were contemporary group (week x room), development diet, and birth weight category. Development diet was not included in the model for WW. Gilts from high and highest IR had significantly (P &lt; 0.05) greater weaning weight (6.5 ± 0.1 kg and 6.5 ± 0.1 kg, respectively), backfat thickness, caliper reading, and flank-to-flank distance at 100 to 200 days, ADG1 (0.45 ± 0.004 kg/day and 0.45 ± 0.007 kg/day, respectively) and ADG2 (0.79 ± 0.005 kg/day and 0.81 ± 0.001 kg/day, respectively) when compared to gilts from lowest IR (5.9 ± 0.2 kg for WW, 0.39 ± 0.008 kg/day for ADG1, and 0.75 ± 0.01 kg/day for ADG2). These data support the concept that neonatal piglet colostrum intake results in improved subsequent growth performance.

20 Nutritional strategies to manage gilt growth and optimize lifetime productivity

Abstract Improving gilt development is key to maximizing sow longevity. How to best manage and feed gilts during development is heavily debated. A series of studies were conducted to determine the optimal feeding program for gilts during development. The hypothesis was that metabolizable energy (ME) and standard ileal digestible lysine could be varied under commercial conditions (ad libitum feeding) to optimize body weight gain and composition, age at puberty, and mammary gland development to support increased productivity of gilts. Studies were conducted in commercial production facilities in Iowa and Utah using large numbers of maternal-line gilts that were monitored, under various dietary treatments from 100 to 200 d of age, for growth, body composition, age at puberty and development of reproductive organs and mammary glands. Varying the dietary Lysine:ME ratio (g:mcal) had modest effects on growth and body composition of gilts. Likewise, development of reproductive organs was minimally affected by diet, but slower growth delayed development of terminal lobular ductal units in mammary glands. Growth rates were slowed by reducing dietary lysine:ME ratio below the requirement and increasing fiber. Gilts still had adequate growth (&gt; 600 g/d) and body composition (≥ 15 mm backfat) for good reproductive performance. Although dietary treatments did not affect the average age of puberty (205 d) or the total number of gilts that reached puberty, a greater percentage of gilts fed higher lysine diets exhibited puberty during the first 40 days of boar exposure. Gilts lost 2 to 3 mm backfat once moved from the development unit to the breeding farms, but pregnancy rates were ≥ 95%. Culling of gilts before first breeding did not vary with diet but was considerably higher than expected. Investigation of how these developmental traits affect productivity through subsequent parities is ongoing.

21 Issues of sow lifetime productivity from an international perspective: from research to production level

Abstract Sow longevity is defined as the time elapsed from gilt entry into the breeding herd until her removal as a result of culling or death. Increasing herd retention rate is important to improve sow lifetime productivity. Higher removal rate implies an increase in the percentage of young females in the herd, a category with lower production potential and a higher risk of early culling. Systematic gilt replacement is required for genetic gain, but it is essential to achieve a retention rate that allows the sows to reach their maximum production potential in the later parities. In this way, it is important to evaluate the reasons for removal and death in order to establish strategies for reducing involuntary culling and controlling mortality rate. Although reproductive failures persist as the main culling cause, its expressivity has been apparently reduced. To improve sow retention rate, management intervention should start during gestation with a focus on improving the replacement gilt’s weight at birth. Ensuring adequate colostrum intake is critical for achieving targeted pre-wean and post-wean growth rate. In addition, approaches that improve gilt body development during the post-weaning phase and up to first breeding are key steps to reducing culling for structural problems and low reproductive performance. In this sense, the use of gilt development units allows a regulated flow of replacement gilts that meet the required parameters recommended by the different genetic suppliers. Because locomotor disorders are frequent reasons for early culling, inspection and maintenance of the animal facilities should be prioritized in all phases of rearing gilts and sows. The opportunity to reduce sow mortality, culling for poor reproduction, and structural failure resides in the ability to translate new research discoveries on gilt birthweight, growth, and body measures into improved lifetime pig production to the 3rd parity.

Gilt Management for Fertility and Longevity.

Simple SummaryImproving sow lifetime productivity, herd stability, and maximizing lifetime performance and longevity in the sow herd, represent significant challenges to the swine industry. Routine implementation of efficient gilt development unit (GDU) programs which deliver high quality, breeding-eligible gilts to the sow farm is still needed. Good gilt management starts at birth, because litter of origin, lactation management and the application of early selection strategies are early indicators of future performance and efficiency. A failure to select gilts with the greatest reproductive potential and inappropriate management of their physiological state and metabolic condition at service, are key risk factors for poor sow lifetime productivity (SLP). Management practices that deliver gilts with the greatest potential SLP are crucial to the productivity of conventional production systems. Substantial evidence supports successful management of gilts as an absolutely necessary component of breeding herd management and the pivotal starting point for the future fertility and longevity of the breeding herd. Therefore, gilt management practices from birth have the potential to influence the future reproductive performance of the sow herd. A good gilt management program will address several key components such as birth traits that determine the efficiency of replacement gilt production; effective selection of the most fertile gilts for entry to the breeding herd; effective management programs that provide a consistent supply of service eligible gilts; and appropriate management of weight, physiological maturity, and a positive metabolic state at breeding. Good gilt management can largely resolve the existing gap between excellent genetic potential and the more modest sow lifetime productivity typically achieved in the industry. Investment in good gilt development programs from birth represents a foundational opportunity for improving the efficiency of the pork production industry.

Effects of energy restriction during gilt development on milk nutrient profile, milk oligosaccharides, and progeny biomarkers.

An ongoing study at the University of Nebraska-Lincoln (which included 14 batches of gilts; n = 90 gilts/batch) demonstrated that energy restriction during the developmental period of a gilt increases longevity and may also have beneficial effects on progeny health and growth, particularly, parity 1 progeny. Therefore, we hypothesized that energy restriction during gilt development may affect milk nutrient profile, milk oligosaccharides (OS), and postnatal progeny biomarkers. During the development period, batch 14 gilts (n = 128, 8 gilts/pen) were fed 3 dietary treatments including the following: 1) Control diet formulated to NRC (2012) specifications (CTL); 2) Restricted (20% energy restriction via addition of 40% soy hulls; RESTR); and 3) CTL diet plus addition of crystalline amino acids equivalent to the SID Lys:ME of the RESTR diet (CTL+). All diets were fed ad libitum and applied in a 3-phase feeding regimen during gilt development (days 123 to 230 of age). Average daily feed intake was used to estimate daily metabolizable energy intake (Mcal/d) during each phase (Phase 1: 10.13, 6.97, 9.95; Phase 2: 11.25, 8.05, 10.94; and Phase 3: 9.47, 7.95,11.07) for CTL, RESTR, and CTL+, respectively. After 230 d of age, gilts were bred and fed a common diet. Milk samples were collected from batch 14 gilts (n = 7 per treatment) on days 0 and 14 postfarrowing for compositional analysis of N, CP, dry matter (DM), GE, insulin, and OS. Piglet blood samples (n = 6 piglets/gilt) were obtained on days 1 and 15 postfarrowing for quantification of glucagon-like peptide-2 (GLP-2) and insulin. No effects of developmental diet were observed for milk N, CP, DM, or GE; however, N, CP, DM, and insulin were increased (P < 0.05) on day 1 compared with day 14. A total of 61 different milk OS were identified. Milk OS profile was significantly different for neutral and acidic OS (P < 0.05) on day 0, but there were no significant differences on day 14. For piglet GLP-2, a treatment by day interaction was observed (P < 0.009); specifically, on day 1 GLP concentrations were greater (P < 0.001) in CTL+ compared with RESTR (6.73 vs. 1.21 ng/mL). For serum insulin, a treatment by day interaction was observed (P < 0.01); specifically, insulin in RESTR progeny was greater (P < 0.03) than CTL on day 1. In conclusion, nutritional management of the developing gilt may affect milk nutrient composition, milk OS profile, and piglet serum biomarkers.

147 Effects of Energy Restriction during Gilt Development on Characterization and Quantification of Milk Oligosaccharides.

147 Effects of Energy Restriction during Gilt Development on Characterization and Quantification of Milk Oligosaccharides.