Two trials were conducted to determine the effects of weaning age on pig performance in a multisite production system. The second trial also evaluated the effects of modifying the nursery feeding program according to weaning age. In Trial 1 (2,272 pigs), treatments included weaning litters at 12, 15, 18, or 21 d of age. In Trial 2 (3,456 pigs), litters were weaned at 15, 16, 18, 19, 21, or 22 d of age and categorized into three treatments (15.5, 18.5, or 21.5 d of age). In Trial 2, pigs in each age group were fed one of two nursery feeding programs. Nursery feeding programs varied in both diet formulation and in the quantity of diets fed containing increased levels of whey and spray-dried animal plasma. Each trial was conducted as a randomized complete block design with four blocks of nursery and finishing sites. All weaning-age treatments were weaned from a 7,300-sow farm on the same day into the same nursery. Each block remained intact as pigs moved from nursery to finishing site. Increasing weaning age (12, 15, 18, or 21 d in Trials 1; and 15.5, 18.5, or 21.5 d in Trial 2) increased (linear, P < 0.001) ADG (299, 368, 409, 474 +/- 7 g/d; 435, 482, 525 +/- 13 g/d) and tended to decrease (linear, P < 0.09) mortality (5.25, 2.82, 2.11, 0.54 +/- 0.76%; 2.17, 1.56, 1.30 +/- 0.36%) in the initial 42 d after weaning. Finishing ADG (722, 728, 736, 768 +/- 11 g/d; 783, 790, 805 +/- 11 g/d) also improved (linear, P < 0.01) with increasing weaning age. Overall, increasing weaning age increased (linear, P < 0.001) wean-to-finish ADG (580, 616, 637, 687 +/- 8 g/d; 676, 697, 722 +/- 6 g/d), weight sold per pig weaned (94.1, 100.5, 104.4, 113.1 +/- 1.3 kg; 107.6, 111.6, 116.2 +/- 1.1 kg), and decreased (linear, P < 0.03) mortality rate (9.4, 7.9, 6.8, 3.6 +/- 0.95%; 3.9, 3.4, 2.5 +/- 0.5%). Altering the nursery feeding program did not affect wean-to-finish growth performance. In this multisite production system, increasing weaning age from 12 to 21.5 d of age increased weight sold per pig weaned by 1.80 +/- 0.12 kg for each day increase in weaning age. These studies suggest increasing weaning age up to 21.5 d can be an effective management strategy to improve wean-to-finish growth performance in multisite pig production.

Animal feed can be contaminated with fomites carrying swine viruses and subsequently be a vehicle for viral transmission. This contamination may not be evenly distributed, and there is no validated sampling method for detection of viruses in animal feed or ingredients. The purpose of this experiment was to evaluate the sensitivity of ingredient sampling methods for detection of porcine epidemic diarrhoea virus (PEDV). No animals were used in this experiment, so approval from an animal ethics committee was not necessary. Thirteen kg soybean meal was used in a 2 × 2 factorial plus a control, with 2 doses of PEDV (Low: 103 TCID50/g versus High: 105 TCID50/g) and two sample types (individual probes versus composite sample). Soybean meal was confirmed PEDV negative, then loaded into individual, 1‐kg polyethylene tote bags with PEDV introduced after loading the first 100 g. There were six replicates per PEDV dose plus a control. Ten individual probes or one composite sample per bag were created and analysed for PEDV via qRT‐PCR. The interaction, dose and sample type were significant for both PEDV presence and quantity. No control samples had detectable PEDV. At the low dose, no PEDV RNA was detected in individual probes or composite samples, but was confirmed in 100% (32.4 Ct) of the inoculant samples. This is likely due to loss of sensitivity during the analysis process, which has been previously reported to cause a loss up to 10 Ct when detecting PEDV in feed or ingredients. At the high dose, only 37% (37.7 Ct) of the probes had detectable PEDV RNA. Composite samples were more sensitive (p < .05), with PEDV RNA detected in 100% of samples (35.7 Ct). In summary, sampling bulk ingredients for PEDV should include compositing at least 10 individual samples. Future research is needed to identify alternative methods that have a similar sensitivity, but require less time and effort to collect such a sample.

Ninety-five pigs (initially 7.1 kg and 24 d of age) were used in a 28-d experiment to determine the effects of Ascophyllum nodosum seaweed extract (ANOD) on young pig growth performance and immune function in response to enteric disease challenge with Salmonella typhimurium (ST). Experimental treatments were arranged in a 2 x 4 factorial with main effects of disease challenge (control vs ST-challenge) and dietary addition of ANOD (0, 0.5, 1.0, and 2.0% of diet). Pigs were fed ANOD diets for 14 d and then challenged orally with ST or sterile media. There were no main effects of ANOD on growth performance end points, although there were significant quadratic effects of ANOD on ADG (P < 0.04) and final weight (P < 0.003), both being greatest at 1.0% ANOD. There was a positive linear effect of ANOD inclusion on ADFI (P < 0.07) and a negative linear effect on the gain-to-feed ratio (G/F) (P < 0.05). ST-challenge reduced ADG (P < 0.05), ADFI (P < 0.05), and G/F (P < 0.05) in the first week following challenge. Daily estimates revealed reductions in feed intake in ST-infected pigs on d 2 to 4 following infection (P < 0.05). Rectal temperature was increased maximally 2 d following ST-infection (P < 0.05). A disease challenge x time interaction (P < 0.001) was observed for serum haptoglobin and alpha1-acid glycoprotein. Serum immunoglobulin M (IgM) was not influenced by disease challenge, but IgM declined (P < 0.001) in all pigs over time. Serum immunoglobulin G (IgG) also was not influenced by disease challenge, but IgG tended (P < 0.08) to increase over time. In vitro culture of porcine alveolar macrophages with 10 mg/mL ANOD elevated (P < 0.05) prostaglandin E2 (PGE2) production over that of controls at 3 and 24 h of culture. There was no interleukin-10 response by porcine splenocytes cultured in vitro with 0.005, 0.05, 0.5, or 5 mg/mL ANOD. We conclude that this model of enteric disease elicits an acute phase response that is accompanied by increased rectal temperature and diminished feed intake. Furthermore, our results indicate some beneficial effects of dietary ANOD on growth performance and no influence of dietary ANOD on immune response in the presence or absence of ST-challenge. However, high ANOD concentrations are capable of activating porcine alveolar macrophages in vitro to secrete PGE2.

A total of 264 pigs (initially 41.0 kg BW) were used in a 90-d study to determine the effects of lowering dietary fiber before market on pigs fed high dietary fiber [provided by wheat middlings (midds) and distillers dried grains with solubles (DDGS)] on growth performance, carcass characteristics, carcass fat quality, and intestinal weights of growing-finishing pigs. Pens of pigs were randomly allotted by initial BW and sex to 1 of 6 treatments with 6 replications per treatment and 7 or 8 pigs per pen. A positive control (corn-soybean meal-based) diet containing no DDGS or midds (9.3% NDF) and a negative control diet with 30% DDGS and 19% midds (19% NDF) were fed throughout the entire trial (d 0 to 90). The other 4 treatments were arranged in a 2 × 2 factorial with the main effects of length of fiber reduction (23 or 47 d before marketing) and fiber level fed during the reduction period (low or medium). Pigs on these treatments were fed the negative control before the reduction treatment. The medium-fiber diet contained 15% DDGS and 9.5% midds (14.2% NDF) with the low-fiber diet was the positive control diet. Increasing the feeding duration of the low-fiber diets lowered overall ADFI (linear, P = 0.03) and improved G:F (linear, P < 0.01). Lowering the fiber level for the last 23 d did not influence growth performance; however, lowering the fiber level improved carcass yield (P = 0.002), with a greater response (P < 0.001) when the low-fiber diet was fed for 23 d. Jowl fat iodine value (IV) decreased when the longer lower fiber diets were fed (linear, P < 0.01) and was lower (P < 0.001) for pigs fed the low-fiber diet during the fiber reduction period than pigs fed the medium-fiber diet during the same time period; however, increasing the time lower fiber diets were fed from 23 to 47 d further reduced (P < 0.01) jowl IV. Increasing the duration that the control diet was fed by increasing the reduction time from 23 to 47 d increased (P < 0.01) backfat depth. Reducing the fiber level decreased full large intestine weight (linear, P = 0.005) with a greater response (P = 0.04) when the low-fiber diet was fed during the reduction period instead of the medium-fiber diet. In summary, lowering the fiber level before marketing can improve G:F, carcass yield, carcass IV, and reduce large intestine weight; however, the optimal duration of the fiber reduction period depends on the targeted response criteria.

Porcine epidemic diarrhea virus (PEDV) is a heat-sensitive virus that has devastated the U.S. swine industry. Because of its heat sensitivity, we hypothesized that a steam conditioner and pellet mill mimicking traditional commercial thermal processing may mitigate PEDV infectivity. Pelleting, a common feed processing method, includes the use of steam and shear forces, resulting in increased temperature of the processed feed. Two thermal processing experiments were designed to determine if different pellet mill conditioner retention times and temperatures would impact PEDV quantity and infectivity by analysis of quantitative reverse transcription PCR and bioassay. In Exp. 1, a 3 × 3 × 2 factorial design was used with 3 pelleting temperatures (68.3, 79.4, and 90.6°C), 3 conditioning times (45, 90, or 180 s), and 2 doses of viral inoculation (low, 1 × 10 tissue culture infectious dose (the concentration used to see cytopathic effect in 50% of the cells)/g, or high, 1 × 10 tissue culture infectious dose/g). Noninoculated and PEDV-inoculated unprocessed mash were used as controls. The low-dose PEDV-infected mash had 6.8 ± 1.8 cycle threshold (Ct) greater ( < 0.05) PEDV than the high-dose mash. Regardless of time or temperature, pelleting reduced ( < 0.05) the quantity of detectable viral PEDV RNA compared with the PEDV-inoculated unprocessed mash. Fecal swabs from pigs inoculated with the PEDV-positive unprocessed mash, regardless of dose, were clinically PEDV positive from 2 to 7 d (end of the trial) after inoculation. However, if either PEDV dose of inoculated feed was pelleted at any of the 9 tested conditioning time × temperature combinations, no PEDV RNA was detected in fecal swabs or cecum content. Based on Exp. 1 results, a second experiment was developed to determine the impact of lower processing temperatures on PEDV quantity and infectivity. In Exp. 2, PEDV-inoculated feed was pelleted at 1 of 5 conditioning temperatures (37.8, 46.1, 54.4, 62.8, and 71.1°C) for 30 s. The 5 increasing processing temperatures led to feed with respective mean Ct values of 32.5, 34.6, 37.0, 36.5, and 36.7, respectively. All samples had detectable PEDV RNA. However, infectivity was detected by bioassay only in pigs from the 37.8 and 46.1°C conditioning temperatures. Experiment 2 results suggest conditioning and pelleting temperatures above 54.4°C could be effective in reducing the quantity and infectivity of PEDV in swine feed. However, additional research is needed to prevent subsequent recontamination after pelleting as it is a point-in-time mitigation step.