Effect of fat sources and combinations on starter pig performance, nutrient digestibility and intestinal morphology

Three growth trials and one digestion trial were conducted to compare the effect of dietary fat sources and combinations on starter pig performance, nutrient digestibility and intestinal morphology. Growth trials 1 and 2, utilizing a total of 324 weanling pigs (21 +/- 3 d), were conducted to determine the influence of addition of soybean oil, coconut oil, choice white grease, 50% soybean oil: 50% coconut oil or 50% choice white grease: 50% coconut oil on starter pig performance. Diets were supplemented with 10% fat for the first 2 wk of the study and with 5% for the final 3 wk. The third growth trial, utilizing a total of 210 weanling pigs, was conducted to evaluate the effects of addition of soybean oil, coconut oil, 50% soybean oil: 50% coconut oil, 75% soybean oil: 25% coconut oil or 25% soybean oil: 75% coconut oil on starter pig performance and nutrient digestibility. Average daily gain and feed/gain were not changed during wk 0 to 2, but they were improved from 3 to 5 wk postweaning when fat was added to the diets. The combination of 50% soybean oil and 50% coconut oil resulted in higher ADG than the other fat combinations. A digestion trial utilizing 24 weanling pigs (21 +/- 3 d) was conducted to evaluate the effects of soybean oil, coconut oil, or combination of soybean oil and coconut oil on morphology of the small intestine and ileal and total tract apparent digestibilities of individual fatty acids, total fatty acids, N, DM and GE from d 5 to 8 postweaning. Pigs fed the combination of soybean oil and coconut oil tended to have increased (P less than .08) villus height compared with pigs fed soybean oil or coconut oil alone. Micrographs revealed intestinal morphology with long, round villi when this combination of oils was fed. These trials demonstrated that a combination of soybean oil and coconut oil improved (P less than .05) pig growth performance over coconut oil alone or with added choice white grease and tended to improve (P less than .12) ileal digestibility of medium-chain fatty acids (less than or equal to 14 C) compared to diets without added fat or containing soybean oil or coconut oil alone.     

Evaluation of the opsonic capacity of core lipopolysaccharide antiserum of equine origin against smooth Escherichia coli 0111:B4, using macrophage chemiluminescence

A study was performed to determine whether equine antiserum to core lipopolysaccharide (LPS) would enhance phagocytosis of smooth gram-negative (GN) organisms by equine macrophages. Five healthy adult horses (group A) were immunized with a bacterin prepared from the J-5 mutant of Escherichia coli 0111:B4 and Salmonella minnesota R595 to produce antibodies to core LPS. Five horses (group B) served as nonimmunized controls and were given physiologic saline solution instead of the rough mutant bacterin. Serum antibody titers to core LPS and to smooth E coli 0111:B4 were determined by indirect ELISA. Four serum pools were prepared: pool 1 = sera from horses in group B prior to immunization; pool 2 = sera from horses in group A prior to immunization (preimmune serum); pool 3 = sera from horses in group B, 7 days after the last saline injection; pool 4 = sera from horses in group A, 7 days after the last immunization (core LPS antiserum). The serum pools, either unheated or heated 30 minutes at 56 C, in 3 dilutions (1/50, 1/100, 1/500) were used to opsonize smooth E coli 0111:B4 in an assay of equine peritoneal macrophage chemiluminescence (CL). Peritoneal fluid was collected from clinically normal horses and the macrophages were purified by adherence to borosilicate glass scintillation vials. Each serum type and dilution was added to triplicate vials containing 10(7) colony-forming units of E coli 0111:B4. Luminol-dependent CL was measured with a liquid scintillation counter in the out-of-coincidence mode. Each serum dilution was tested in duplicate vials without bacteria to asses serum-induced nonspecific CL.(ABSTRACT TRUNCATED AT 250 WORDS)     

Risk of exposure to Coxiella burnetii from ruminant livestock exhibited at Iowa agricultural fairs

Coxiella burnetii is a zoonotic pathogen typically associated with clinical and asymptomatic infection in ruminant livestock. A re‐emerging pathogen of significant public health importance, C. burnetii has caused recent epidemics in the United States and Europe, and public livestock exhibitions are increasingly scrutinized as a potential source of C. burnetii exposure. Although C. burnetii prevalence data among North American domestic ruminants are extremely limited, contemporary studies suggest that this pathogen is both geographically widespread and highly prevalent on a herd basis, especially in dairy cattle and goat populations. We utilized a real‐time PCR assay to detect C. burnetii faecal shedding by clinically normal, non‐periparturient beef cattle, meat goats and sheep exhibited at Iowa agricultural fairs. Individual faecal samples were collected from beef cattle, meat goats and sheep exhibited at twelve Iowa county fairs during the summer of 2009. The sample pool was blocked by species and fair, and ten samples from each block were randomly selected for the diagnostic assay; this test pool is considered sufficient to identify with 95% confidence a shedding animal in a population prevalence of 2.85% (cattle and sheep) and 6.25% (goats). Detection of C. burnetii DNA was determined through use of a real‐time PCR assay validated for use in bovine, ovine and caprine faeces; threshold of detection is one DNA copy per PCR (sensitivity 95.8%, specificity 100%). All tested samples were negative for C. burnetii DNA. We conclude that non‐dairy, non‐periparturient ruminants exhibited at Iowa fairs are unlikely to shed C. burnetii in their faeces and that this population should not be considered to be a significant exposure risk to other livestock or fair attendees.     

PRRSV2 genetic diversity defined by RFLP patterns in the United States from 2007 to 2019

The genetic diversity of porcine reproductive and respiratory syndrome virus (PRRSV) increases over time. In 1998, restriction-fragment length polymorphism (RFLP) pattern analysis was introduced to differentiate PRRSV wild-type strains from VR2332, a reference strain from which a commercial vaccine (Ingelvac PRRS MLV) was derived. We have characterized here the PRRSV genetic diversity within selected RFLP families over time and U.S. geographic space, using available ISU-VDL data from 2007 to 2019. The 40,454 ORF5 sequences recovered corresponded to 228 distinct RFLPs. Four RFLPs [2-5-2 (21.2%), 1-7-4 (15.6%), 1-4-4 (11.8%), and 1-8-4 (9.9%)] represented 58.5% of all ORF5 sequences and were used for cluster analysis. Over time, there was increased detection of RFLPs 2-5-2, 1-7-4, 1-3-4, 1-3-2, and 1-12-4; decreased detection of 1-4-2, 1-18-4, 1-18-2, and 1-2-2; and different detection trends for 1-8-4, 1-4-4, 1-26-1, 1-22-2, and 1-2-4. An over-time cluster analysis revealed a single cluster for RFLP 2-5-2, supporting that sequences within RFLP 2-5-2 are still relatively conserved. For 1-7-4, 1-4-4, and 1-8-4, there were multiple clusters. State-wise cluster analysis demonstrated 4 main clusters for RFLP 1-7-4 and 1-8-4, and 6 for RFLP 1-4-4. For the other RFLPs, there was a significant genetic difference within them, particularly between states. RFLP typing is limited in its ability to discriminate among different strains of PRRSV. Understanding the magnitude of genetic divergence within RFLPs helps develop PRRSV regional control programs, placement, herd immunization strategies, and design of appropriate animal movements across borders to minimize the risk of PRRSV transmission.     

Extension plant pathology: strengthening resources to continue serving the public interest

Extension plant pathologists deliver science-based information that protects the economic value of agricultural and horticultural crops in the United States by educating growers and the general public about plant diseases. Extension plant pathologists diagnose plant diseases and disorders, provide advice, and conduct applied research on local and regional plant disease problems. During the last century, extension plant pathology programs have adjusted to demographic shifts in the U.S. population and to changes in program funding. Extension programs are now more collaborative and more specialized in response to a highly educated clientele. Changes in federal and state budgets and policies have also reduced funding and shifted the source of funding of extension plant pathologists from formula funds towards specialized competitive grants. These competitive grants often favor national over local and regional plant disease issues and typically require a long lead time to secure funding. These changes coupled with a reduction in personnel pose a threat to extension plant pathology programs. Increasing demand for high-quality, unbiased information and the continued reduction in local, state, and federal funds is unsustainable and, if not abated, will lead to a delay in response to emerging diseases, reduce crop yields, increase economic losses, and place U.S. agriculture at a global competitive disadvantage. In this letter, we outline four recommendations to strengthen the role and resources of extension plant pathologists as they guide our nation's food, feed, fuel, fiber, and ornamental producers into an era of increasing technological complexity and global competitiveness.     

Energy use in pig production: an examination of current Iowa systems

This paper compares energy use for different pig production systems in Iowa, a leader in US swine production. Pig production systems include not only the growth and performance of the pigs, but also the supporting infrastructure of pig production. This supporting infrastructure includes swine housing, facility management, feedstuff provision, swine diets, and manure management. Six different facility type × diet formulation × cropping sequence scenarios were modeled and compared. The baseline system examined produces 15,600 pigs annually using confinement facilities and a corn-soybean cropping sequence. Diet formulations for the baseline system were corn-soybean meal diets that included the synthetic AA l-lysine and exogenous phytase. The baseline system represents the majority of current US pork production in the Upper Midwest, where most US swine are produced. This system was found to require 744.6 MJ per 136-kg market pig. An alternative system that uses bedded hoop barns for grow-finish pigs and gestating sows would require 3% less (720.8 MJ) energy per 136-kg market pig. When swine production systems were assessed, diet type and feed ingredient processing were the major influences on energy use, accounting for 61 and 79% of total energy in conventional and hoop barn-based systems, respectively. Improving feed efficiency and better matching the diet formulation with the thermal environment and genetic potential are thus key aspects of reducing energy use by pig production, particularly in a hoop barn-based system. The most energy-intensive aspect of provisioning pig feed is the production of synthetic N for crop production; thus, effectively recycling manure nutrients to cropland is another important avenue for future research. Almost 25% of energy use by a conventional farrow-to-finish pig production system is attributable to operation of the swine buildings. Developing strategies to minimize energy use for heating and ventilation of swine buildings while maintaining pig comfort and performance is a third critical area for future research. The hoop barn-based alternative uses 64% less energy to operate buildings but requires bedding and 2.4% more feed. Current Iowa pig production systems use energy differently but result in similar total energy use. Compared with 1975, current farrow-to-finish systems in Iowa require 80% less energy to produce live market pigs.