151 Impact of Feed Allotment During the Wean-To-Estrus Interval on Sow Reproductive Performance

Pork producers have recently inquired whether the allotment of feed should be greater during the wean-to-estrus interval to optimize sow performance. The objective of this experiment was to validate the amount of feed allotted to sows during the wean-to-estrus interval to optimize feed costs and farrowing performance. A total of 257 PIC 1050 (PIC, Inc., Hendersonville, TN) weaned sows were blocked to 3 body condition categories (thin, ideal, or heavy, respectively) and then randomly allotted to 1 of 2 feed quantity treatments (2.7 or 5.4 kg, respectively) on d 0. The sows used in this experiment were housed under commercial conditions and had an average parity of 3.15. One day prior to weaning, each sow was calipered to determine body condition and feed boxes were validated to determine that the desired amount of feed was actually allocated during the experimental period. Sows were fed their allotted amount of feed (2.7 or 5.4 kg, respectively) from d 0 till the sows were serviced or if the sows had not been detected in estrus until d 8. Sows were tracked through their subsequent wean to detect any downstream differences. Data were analyzed using Proc MIXED (SAS 9.4; Cary, NC) with sow as the experimental unit, treatment as the main effect, and caliper score as the block criteria. These data indicate that allocating 5.4 kg of feed did not improve wean-to-first service interval (2.7 kg = 4.4 d vs. 5.4 kg = 4.4 d; P = 0.99), farrowing rate (2.7 kg = 91.5% vs. 5.4 kg = 90.6%; P = 0.81), or total born (2.7 kg = 15.9 vs. 5.4 kg = 15.4 pigs/litter; P = 0.31). In summary, feeding greater than 2.7 kg of feed from wean-to-estrus does not improve sow performance, but does increase feed costs.

108 Quantifying the Presence of Viral Material in Feed Delivered in Iowa

Experimental models have shown that viral genetic material can be found in feedstuffs for over 150 d and experimental viral contamination of feed can cause viral diseases in pigs. However, the actual risk of feed being a fomite for viruses that cause PRRS, PED, PDCoV, and TGE in everyday pork production has yet to be determined. Thus, our objective was to quantify the viral presence in 224 feed samples delivered throughout Iowa in 2 periods of the year. The first period was from November 29th, 2020 through February 20th, 2021, during the period of suspected seasonally elevated virus pressure. The second period was from June 6th through July 3rd, 2021, during the period of suspected decreased virus pressure. We hypothesized that fewer than 2 of the 224 feed samples would result in a positive PCR test. To test our hypothesis and accomplish our experimental objective, 1 feed sample was collected per feed mill (14) for each of 16 weeks (12 in the winter collection period and 4 in the summer collection period; [n = 224]). Each feed sample was collected at the mill during the loading of the feed truck before delivery. Post collection each feed sample was identified and then shipped to the Veterinary Diagnostic Laboratory at Iowa State University. All collected feed samples were tested via PRRSV PCR and PEDV/PDCoV/TGEV multiplex PCR. The Veterinary Diagnostic Laboratory at Iowa State University declared Ct values >37 a negative (-) result for PRRSV and >36 a negative (-) result for PEDV, PDCoV, and TGEV. Of the 224 collected feed samples, 0 tested positive for PRRSV. Of the 224 collected feed samples, 0 tested positive for PEDV, PDCoV, and TGEV. These results do not disprove that feed can be a fomite of domestic and foreign animal diseases. These results just provide a data point for pork producers to evaluate the actual risk of feed being a fomite of PRRSV, PEDV, PDCoV, and TGEV.

139 Does Feeding an Increased Level of Narasin (Skycis) Result in Improved Growth Performance and Mortality in a Commercial Wean-to-finish Swine Feeding Program?

The response to narasin (Skycis 100, Elanco, Greenfield, IN) to date has been documented in research facilities with a high degree of control and via pigs with no insults to health or feed intake. Furthermore, these studies are always conducted on a single subset of pigs and diets. However, in commercial conditions, the response to narasin must be consistent and defined over a wide range of health statuses, stocking densities, feed intakes, environments, and diet formulations. The objective of this experiment was to determine which inclusion level of narasin (13.6 or 18.1 g/ton) would provide the greatest response under commercial conditions. A total of 197,629 weaned barrows and gilts (6.0 ± 0.1 kg; PIC 337 sired, Hendersonville, TN) were placed in 73 2,400-head commercial wean-to-finish barns that were alternated to 1 of 2 treatments (13.6 or 18.1 g of narasin/ton) in a rolling allotment over an 18-month period. Pigs were on the experiment for an average of 163 ± 1.6 days (until harvest). Throughout the 18-month experimental period, diets (outside of the narasin inclusion) were allowed to change to maximize return over feed costs. Data were analyzed using Proc MIXED (SAS 9.4; Cary, NC) with treatment as the main effect and barn as the experimental unit. Compared to 13.6 g/ton, the increased level of narasin (18.1 g/ton) improved ADG (13.6 g/ton = 0.76 versus 18.1 g/ton = 0.78 kg/d; P = 0.035), gain:feed (13.6 g/ton = 0.389 versus 18.1 g/ton = 0.401; P = 0.042), and mortality from wean to harvest (13.6 g/ton = 7.2% versus 18.1 g/ton = 5.3%; P = 0.084). In summary, feeding an increased level of narasin (18.1 g/ton) during an ever-changing (diet formulation, environment, and health status) commercial experimental conditions resulted in greater growth performance and reduced mortality.

120 Impact of a Two-phase Lactation Feeding Program on Farrowing and Weaning Performance of Sows

The U.S. Pork Industry uses a one-phase lactation feeding program based on logistical constraints and ease. The objective of this experiment was to quantify the sow performance differences between a one-phase and two-phase lactation feeding program to allow pork producers to calculate the economics of switching to a two-phase lactation feeding program. 257 gilts and sows (PIC 1050; Hendersonville, TN) were randomly assigned to a two-phase or one-phase lactation feeding program. Animals on the one-phase treatment were fed a typical lactation diet (2.55 Mcal/kg NE, 12.7% NDF, 0.99% SID Lys) for the duration of the experiment. Animals on the two-phase treatment were fed a high-fiber, lower-lysine transition diet (2.35 Mcal/kg NE, 18.5% NDF, 0.65% SID Lys) from the time they were loaded into the farrowing room until switching to the lactation diet on d 3 post-farrowing. From loading to farrowing, animals on both treatments were fed 1.82 kg/d, split between 2 meals at 630 and 1530 h. Daily feed amount was increased on the farrowing day and the 2 subsequent days (2.73, 4.09, 5.45 kg) until allowed ad libitum access to the lactation feed for both treatment groups on the third day after farrowing. Data were analyzed using Proc MIXED (SAS 9.4; Cary, NC) with treatment as the main effect and sow as the experimental unit. Comparing treatments, no significant differences on total born (one-phase = 16.2 vs. two-phase = 16.0, pigs/litter), live born (one-phase = 14.6 vs. two-phase = 14.4, pigs/litter), stillborn rate (one-phase = 8.1% vs. two-phase = 7.4%), number weaned (one-phase = 12.1 vs. two-phase = 11.9, pigs/litter), or weaning weight (one-phase = 5.67 vs. two-phase = 5.71, kg/pig; P ≥ 0.37) were detected. In conclusion, a two-phase lactation feeding program did not impair sow performance can be utilized to reduce lactation feed costs by $0.42/female/lactation cycle.

195 Does Feeding a Protease and Probiotic (Bacillus Subtilis) Combination (Syncra® SWI) Result in Improved Growth Performance and Mortality in a Commercial Wean-to-finish Swine Feeding Program?

The response to probiotics and enzymes is often documented in research facilities with a high degree of control and via pigs with no insults to health or feed intake. However, in commercial conditions, the response to feed additives promoting advanced gut health and improved digestion must be consistent and defined over a wide range of health statuses, stocking densities, feed intakes, environments, and diet formulations. The objective of this experiment was to determine if a combined feed protease and probiotic system (Syncra® SWI 201, DuPont, Wilmington, DE) would improve growth performance and mortality under commercial conditions. A total of 127,092 pigs (6.0 ± 0.1 kg; PIC 337 sired, Hendersonville, TN) from a sow farm producing porcine reproductive and respiratory virus and rotavirus positive weaned pigs were placed in 53 2,400-head commercial wean-to-finish barns that were alternated to 1 of 2 treatments (a control treatment without Syncra® SWI (SSWI) or with SSWI included at 72.6 g/ton of finished feed from 22.7 kg of BW to harvest) in a rolling allotment over a 12-month period. Pigs were on the experiment for an average of 162 ± 1.0 days (until harvest). Throughout the 12-month experimental period, diets (outside of the SSWI inclusion) could change in order to maximize return over feed costs. Data were analyzed using Proc MIXED (SAS 9.4; Cary, NC) with treatment as the main effect and barn as the experimental unit. Compared to the control, adding SSWI improved mortality by 1.9% and percent grade 1 marketed pigs by 2.2% (P ≤ 0.025). Compared to the control, SSWI did not improve ADG (control = 0.75 vs. SSWI = 0.78 kg) or gain:feed (control = 0.401 vs. SSWI = 0.396). In conclusion, the inclusion of the SSWI combined feed protease and probiotic system can improve mortality and grade 1 marketed pigs, but not growth performance under commercial conditions.

276 Impact of pre-farrow feeding amount and timing on stillborn rate of sows

Pre-farrowing feeding allowance and timing are often based on logistical ease instead of optimizing farrowing performance. The objective of this experiment was to decrease the stillborn rate via the amount and timing of feeding prior to farrowing. A total of 245 PIC 1050 (PIC, Inc., Hendersonville, TN) individually housed bred females were randomly allotted to 1 of 3 treatments on d 0. The 3 pre-farrow feeding treatments consisted of: 1) 2 meals of 0.9 kg fed at 630 h and 1530 h; 2) 1 meal of 1.8 kg fed at 630 h; and 3) 2 meals of 2.7 kg fed at 630 h and 1530 h. Dietary treatment commenced on entry into the farrowing crate and continued until they farrowed (ranged from d 2 to d 10). Data were analyzed using Proc MIXED (SAS 9.4; Cary, NC) with treatment as the main effect and sow as the experimental unit. Females having a litter with a total born ≤ 11 or ≥ 21 or did not consume their allotted feed were considered outliers and were removed from the statistical analysis. Feeding 2 meals of 0.9 kg per day trended to reduce stillborn rate compared to the other 2 pre-farrow feeding treatments (2 meals of 0.9 kg = 5.6%, 1 meal of 1.8 kg = 8.6%, 2 meals of 2.7 kg = 9.0%; P = 0.090). Pre-farrow feeding amount and time had no impact on total born or mummies (P ≥ 0.270). As a bonus, feeding small meals multiple times a day will reduce the farm’s overall feed cost compared to providing full feed access pre-farrow. In conclusion, implementation of a pre-farrowing feeding strategy is a vehicle that can be used to reduce the stillborn rate in commercial production.

The digestible energy, metabolizable energy, and net energy content of dietary fat sources in thirteen- and fifty-kilogram pigs

The objective was to determine the energy concentration of a diverse array of dietary fat sources and, from these data, develop regression equations that explain differences based on chemical composition. A total of 120 Genetiporc 6.0 × Genetiporc F25 (PIC, Inc., Hendersonville, TN) individually housed barrows were studied for 56 d. These barrows (initial BW of 9.9 ± 0.6 kg) were randomly allotted to 1 of 15 dietary treatments. Each experimental diet included 95% of a corn-soybean meal basal diet plus 5% either corn starch or 1 of 14 dietary fat sources. The 14 dietary fat sources (animal-vegetable blend, canola oil, choice white grease source A, choice white grease source B, coconut oil, corn oil source A, corn oil source B, fish oil, flaxseed oil, palm oil, poultry fat, soybean oil source A, soybean oil source B, and tallow) were selected to provide a diverse and robust range of unsaturated fatty acid:SFA ratios (U:S). Pigs were limit-fed experimental diets from d 0 to 10 and from d 46 to 56, providing a 7-d adaption for fecal collection on d 7 to 10 (13 kg BW) and d 53 to 56 (50 kg BW). At 13 kg BW, the average energy content of the 14 sources was 8.42 Mcal DE/kg, 8.26 Mcal ME/kg, and 7.27 Mcal NE/kg. At 50 kg BW, the average energy content was 8.45 Mcal DE/kg, 8.28 Mcal ME/kg, and 7.29 Mcal NE/kg. At 13 kg BW, the variation of dietary fat DE content was explained by DE (Mcal/kg) = 9.363 + [0.097 × (FFA, %)] - [0.016 × omega-6:omega-3 fatty acids ratio] - [1.240 × (arachidic acid, %)] - [5.054 × (insoluble impurities, %)] + [0.014 × (palmitic acid, %)] ( = 0.008, = 0.82). At 50 kg BW, the variation of dietary fat DE content was explained by DE (Mcal/kg) = 8.357 + [0.189 × U:S] - [0.195 × (FFA, %)] - [6.768 × (behenic acid, %)] + [0.024 × (PUFA, %)] ( = 0.002, = 0.81). In summary, the chemical composition of dietary fat explained a large degree of the variation observed in the energy content of dietary fat sources at both 13 and 50 kg BW.

The composition of dietary fat alters the transcriptional profile of pathways associated with lipid metabolism in the liver and adipose tissue in the pig

The objective was to investigate the of effect chemical composition of dietary fat on transcription of genes involved in lipid metabolism in adipose tissue and the liver via transcriptional profiling in growing pigs. A total of 48 Genetiporc 6.0 × Genetiporc F25 (PIC, Inc., Hendersonville, TN) barrows (initial BW of 44.1 ± 1.2 kg) were randomly allotted to 1 of 6 dietary treatments. Each experimental diet included 95% of a corn-soybean meal basal diet and 5% cornstarch (control; CNTR), animal-vegetable blend (AV), coconut oil (COCO), corn oil (COIL), fish oil (FO), or tallow (TAL). Pigs were sacrificed on d 10 (final BW of 51.2 ± 1.7 kg) to collect tissues. Expression normalization across samples was performed by calculating a delta cycle threshold (ΔCt) value using . Delta delta cycle threshold (ΔΔCt) values were expressed relative to the CNTR treatment. In adipose tissue, adding dietary fat, regardless of the source, decreased the mRNA abundance of compared with the CNTR ( = 0.014). Pigs fed a COIL-based diet tended to have greater adipose tissue expression of ( = 0.071) than pigs fed the other dietary fat sources tested. Abundance of mRNA was greater in adipose tissue of barrows a fed COIL-based diet than barrows fed CNTR or FO-based diets ( = 0.047). In the liver, adding dietary fat, regardless of source, increased the mRNA abundance of , , , , , and ( ≤ 0.020) and tended to increase the abundance of ( = 0.071) and ( = 0.086) compared with the CNTR. Pigs fed a TAL-based diet had greater hepatic transcription of than pigs fed CNTR-, COCO-, or FO-based diets ( = 0.013). Hepatic transcription of tended to be greater in pigs fed COCO than in pigs fed other dietary fat sources ( = 0.074). Dietary omega-3 fatty acid content tended to negatively correlate with mRNA abundance of ( = 0.065) in adipose tissue and ( = 0.063) in the liver. Dietary fat SFA content was negatively correlated with in the liver ( ≤ 0.039). Dietary fat MUFA content tended to be positively correlated with , , and mRNA abundance in the liver ( ≤ 0.100). To conclude, the intake of omega-3 fatty acids suppressed the mRNA abundance of genes involved in lipolysis in both adipose tissue and the liver. Dietary SFA are greater inhibitors of lipogenesis in adipose tissue than omega-6 fatty acids. Intake of medium-chain fatty acids alters hepatic lipid metabolism differently than intake of long-chain fatty acids.

Prediction of porcine carcass iodine value based on diet composition and fatty acid intake

The pig industry uses a variety of fat sources (FS) and fat levels (FL) in diets to increase energy content. The objective was to investigate the impact of FS and FL on rate and efficiency of gain, apparent total tract digestibility of dietary fat, and pork fat composition and test dietary predictors of carcass iodine value (IV). A total of 1,213 pigs (PIC 280 × PIC Camborough 42; PIC, Inc., Hendersonville, TN) with an initial BW of 32.0 ± 0.4 kg were randomly allotted to 1 of 6 dietary treatments on d 0. Treatments were arranged as a 2 × 3 factorial, with 2 FS, choice white grease (CWG; IV = 66.8) and corn oil (COIL; IV = 123.2), and 3 FL, 2, 4, or 6%. Ten pens of approximately 20 pigs each (0.70 m/pig) were randomly assigned to each of the 6 treatments. All pigs were on trial for 105 d. Pigs were harvested in 1 of 3 marketing pulls, to achieve an ideal market BW across differing rates of gain, at which time belly fat samples were collected (d 105 [457 pigs], 117 [309 pigs], or 134 [432 pigs]). Diet and belly fat samples were analyzed for fatty acid profile. Daily rate of gain was not impacted by FS or FL ( ≤ 0.325). Increasing FL and dietary energy concentration increased G:F ( < 0.001). No difference was evident for G:F between FS ( = 0.107). Increasing FL of CWG resulted in greater daily intake of SFA and MUFA than increasing FL of COIL ( < 0.001). Increasing levels of COIL resulted in greater daily intake of PUFA than increasing levels of CWG ( ≤ 0.012). Feeding CWG tended to result in great caloric efficiency adjusted for carcass yield than feeding COIL ( = 0.074). The inclusion of COIL instead of CWG tended to increase true total tract digestion of acid hydrolyzed ether extract on d 39 ( = 0.066) but not on d 104 ( = 0.402). Increasing COIL increased carcass IV at a greater magnitude than increasing CWG, resulting in a FS × FL interaction on d 105, 117, and 134 ( < 0.001). Dietary linoleic acid concentration and daily intake had a stronger linear relationship than IV product (IVP; = 0.95 vs. = 0.94 vs. = 0.85, respectively). In conclusion, limiting linoleic acid dietary concentration and intake is key to lowering carcass IV. To meet a carcass IV standard of 74 g/100 g, linoleic acid concentration had to be <3.4% and intake had to be <88 g/d. Dietary linoleic acid is a superior predictor of carcass IV compared with IVP, especially when high-fat diets are used.

The impact of dietary fat withdrawal on carcass iodine value, belly characteristics, and changes in body fat over time

The inclusion of unsaturated fats in pig diets has raised issues related to pork carcass fat quality. The objective of this experiment was to understand how withdrawal from the diet of unsaturated dietary fat before slaughter impacts the composition of jowl fat during the growth cycle and at market. Fifty individually housed pigs (PIC 337 × C22/29; initial BW = 59.3 ± 0.55 kg) were allotted based on sex and initial BW to 10 treatments for an 82-d experiment as follows: 3 dietary fat withdrawal times before slaughter (21, 42, or 63 d) by 3 dietary fat unsaturation loads (DFUL), which includea high intake of unsaturated fatty acids supplied through an inclusion of 5% corn oil (HIGH), a high intake of a mixture of saturated and unsaturated fatty acids supplied through an inclusion of 5% animal-vegetable blend (MED), and a moderate intake of unsaturated fatty acids supplied through an inclusion of 2.5% corn oil (LOW). Pigs were weighed and jowl adipose samples were collected on d 0, 21, 42, and 63 and at harvest on d 82. Data were analyzed using PROC MIXED with treatment and sex as fixed effects. At market (d 82), increasing the withdrawal of dietary fat further away from market increased 18:1 (P = 0.045) and tended to increase 14:0 concentrations (P = 0.054). It also significantly decreased 18:2 (P < 0.001) and tended to decrease 18:3 concentrations (P = 0.081). A HIGH DFUL resulted in the greatest 18:2 concentrations in jowl fat followed by LOW; MED resulted in the lowest 18:2 levels (P < 0.001). Dietary fat withdrawal before market significantly reduced carcass iodine value (IV) measured at d 82 (P = 0.006). In conclusion, elevated 18:2 intake makes lowering carcass IV in the depot fat very difficult and may take as long as 61 d. The withdrawal of unsaturated dietary fat apparently altered the fat depot to be more reflective of fat synthesized de novo, resulting in a more saturated depot fat. Importantly, this alteration of deposited fat composition did not translate into improved belly firmness, depth, weight, or fat color.

Characteristics of lipids and their feeding value in swine diets

In livestock diets, energy is one of the most expensive nutritional components of feed formulation. Because lipids are a concentrated energy source, inclusion of lipids are known to affect growth rate and feed efficiency, but are also known to affect diet palatability, feed dustiness, and pellet quality. In reviewing the literature, the majority of research studies conducted on the subject of lipids have focused mainly on the effects of feeding presumably high quality lipids on growth performance, digestion, and metabolism in young animals. There is, however, the wide array of composition and quality differences among lipid sources available to the animal industry making it essential to understand differences in lipid composition and quality factors affecting their digestion and metabolism more fully. In addition there is often confusion in lipid nomenclature, measuring lipid content and composition, and evaluating quality factors necessary to understand the true feeding value to animals. Lastly, advances in understanding lipid digestion, post-absorption metabolism, and physiological processes (e.g., cell division and differentiation, immune function and inflammation); and in metabolic oxidative stress in the animal and lipid peroxidation, necessitates a more compressive assessment of factors affecting the value of lipid supplementation to livestock diets. The following review provides insight into lipid classification, digestion and absorption, lipid peroxidation indices, lipid quality and nutritional value, and antioxidants in growing pigs.

Impact of dietary fat source and concentration and daily fatty acid intake on the composition of carcass fat and iodine value sampled in three regions of the pork carcass

The increased inclusion of unsaturated fats in pig diets has raised issues related to pork carcass fat quality. The objective of this experiment was to more precisely measure how differing levels of daily fatty acid intake alters the fatty acid composition in 3 different fat depots. A total of 42 gilts and 21 barrows (PIC 337×C22/29) with an average initial weight of 77.80±0.38 kg were allotted randomly based on sex and BW to 7 treatments: 3 and 6% of each of tallow (TAL; iodine value [IV]=41.9), choice white grease (CWG; IV=66.5), or corn oil (CO; IV=123.1) and a control (CNTR) corn-soybean meal-based diet with no added fat. Pigs were individually housed to allow accurate measurement of individual feed intake, in particular, daily dietary fatty acid and energy intake. Fat samples were collected from the jowl, belly, and loin at slaughter. Diet and carcass fat samples were analyzed for IV. Belly weights were recorded at slaughter along with a subjective belly firmness score (1=firmest to 3=least firm). Carcass lipid IV was increased (P<0.001) by increasing the degree of unsaturation of the dietary fat source (66.8, 70.3, and 76.3 for TAL, CWG, and CO, respectively). Carcass lipid IV for TAL and CWG was not affected (P>0.05) by inclusion levels; however, carcass lipid IV was greater (P<0.001) in pigs fed 6 than 3% CO (80.0 vs. 72.6), and carcasses of gilts had greater IV (P<0.001) than carcasses of barrows (71.5 vs. 69.1). Increasing the level of TAL and CO but not CWG from 3 to 6% decreased the apparent total tract digestibility of GE, resulting in a source×level interaction (P<0.05). Dietary fat source had no effect (P≥0.66) on apparent total tract digestibility of either DM or GE, but feeding 6% dietary fat increased G:F (P=0.006) over pigs fed 3% fat (0.358 vs. 0.337). Of all the fatty acids measured, only linoleic acid intake presented a reasonable coefficient of determination (R2=0.61). Overall, IV product (IVP) was approximately equal to linoleic acid intake as a predictor of carcass IV (R2=0.93 vs. R2=0.94). When inclusion of dietary fat and PUFA intake increased, IVP placed more emphasis on the dietary fat inclusion level rather than the dietary fat composition. Linoleic acid intake corrected the overemphasis placed on dietary fat inclusion by IVP. To conclude, linoleic acid intake showed a strong relationship with carcass IV and can be used as a predictor.

Speciated hydrocarbon emissions from small utility engines

Partially speciated hydrocarbon (HC) emissions data from several small utility engines, as measured by a Fourier Transform Infrared analyzer, are presented. The engines considered have nominal horsepower ratings between 3.7 and 9.3 kW. Both side-valve and overhead-valve engines are studied, and four different fuels are used in the engines. The results indicate that the small HCs present in the exhaust tend to be in the form of either methane or unsaturated HCs. Other small alkanes, such as ethane and propane, are present in only relatively small concentrations. In terms of ozone formation potential, the HCs in the form of methane will lead to little ozone, but the distribution of the C2 and C3 species is not ideal from an ozone reduction stand-point. It is also found that the presence of oxygen in the fuels appears to lead to somewhat more complete combustion, although the effects are not large. Finally, the overhead-valve engines appear to have lower HC emissions than side-valve engines, which is primarily due to higher operating A/F ratios and the engine geometry.