151 A Web Application to Establish Customized Feeding Program and Nutrient Specifications for Highly Prolific Sows

A web application was developed to provide a dynamic feeding program for PIC maternal dam lines during gilt development, gestation, peri-partum, lactation and wean-to-service interval (WSI). These recommendations for each production phase are based on peer-reviewed large-scale commercial research. The tool was developed using the Shiny package of R and includes CSS themes, html widgets, and JavaScript actions. Inputs, include pigs weaned per sow per year (PWSY), farrowing rate (FR), total born (TB), replacement rate, the existing feeding program of the breeding herd and the diet energy and standardized ileal digestible (SID) lysine (Lys) levels. Outputs include the feeding program, nutrient specifications and estimates of economic opportunity and performance improvement. The feeding program is based on user-defined energy and SID Lys levels for the gestation and lactation diets and the PIC nutrient recommendations for the breeding herd. Correspondingly, recommended specifications of other nutrients in the diets are provided and calculated based on the recommended feeding program. The tool provides economic and productivity opportunity analysis by comparing the PIC recommendations and the current user feeding programs. Improvement in PWSY is driven by the energy intake impact on caliper score during breeding and farrowing and consequently to FR and TB. This web application can be used by nutritionists and production managers to compare their current feeding practices to PIC recommendations for highly prolific sows. This will aid in their decision-making process regarding nutrition and feeding programs considering productivity and profitability outcomes.

263 Review of Current Nutrition Knowledge and Practices for Gilt Development

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.

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

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.

PSII-18 Dietary Strategy for Gilt Development

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.

Modeling the transmission and vaccination strategy for porcine reproductive and respiratory syndrome virus

SummaryMany 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 2%, 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.

22 Poor management of breeding herd replacements is a key factor in poor sow lifetime productivity: Gilty as charged

Recently published research on gilt development using contemporary commercial dam-lines has confirmed: 1) That the growth performance of gilts is rarely below the lifetime growth rate of 0.55 kg.d that would limit the onset of sexual maturity; 2) The majority of gilts provided direct daily contact with mature boars from 160 days of age reach puberty by 200 days of age and represent a normal distribution of “early responders”; 3) Gilts that respond later to boar stimulation have poorer lifetime fertility and tend to be over weight at breeding; 4) Pubertal responses to direct boar contact are significantly higher than responses to fenceline contact with boars; 5) Even if pubertal responses to direct boar contact are delayed in particular cohorts of gilts, good pubertal responses to exogenous, low-dose eCG/hCG treatments (PG600) allow efficient replacement gilt flows to be maintained in most commercial situations; 6) Delaying breeding until second observed estrus, and providing at least 10 days of acclimation to individual stall accommodation, maximizes first litter performance. When gilts were managed in purpose designed facilities that allowed daily records of vulval and behavioral responses to effective boar stimuli to be recorded, the lifetime reproductive performance of know pubertal gilts entering the breeding herd exceeded industry benchmarks. Of 2,374 naturally cyclic and 741 PG600-induced gilts delivered to the breeding herd, 97.6 and 95.7%, respectively, were bred, 94.7 and 92.0%, respectively, farrowed a first litter and 70.6 and 65.3%, respectively, farrowed a fourth litter. In terms of key factors other than reproductive performance that affect retention rate, another recent large-scale study of commercial replacement gilts derived from multiplication sows with a known litter birth weight phenotype confirmed data based on individual gilt birth weight, in that high growth rates linked to heavy weights at breeding were a major risk factor for early removal from the breeding herd. Therefore, poor gilt management must still be viewed as a major factor limiting breeding herd performance.

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

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 < 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 < 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 < 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.

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

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 < 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 < 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 > 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.