Spread of Porcine Circovirus Associated Disease (PCVAD) in Ontario (Canada) Swine Herds: Part II. Matched Case-control Study

Posted in: Ontario Pork, Pork Insight Articles by admin on August 20, 2010 | No Comments

The primary objective of this study was to evaluate risk factors for incidence cases of reported PCVAD. A time-matched case-control study was used as a study design approach, and conditional logistic regression as the analytical method. Briefly, 278 herds located in southern Ontario were included in this study initially using two different sampling mechanisms: (i) sampling of herds positive for porcine reproductive and respiratory syndrome virus (PRRSv) using data from a diagnostic laboratory (Animal Health Laboratory, University of Guelph, Guelph, ON, Canada), based on rtPCR-positive diagnostic findings, and (ii) sampling of PRRSv-negative herds, based on assessment of a herd veterinarian. Herds were classified into PCVAD-positive and negative herds on the basis of producers’ assessments, and results obtained during exploratory spatial analysis were used to guide the design of this case-control study. In conclusion, the spread of PCVAD due to high-risk local exposure was primarily driven by herd ownership. It was therefore impossible to distinguish local spread from common direct or indirect sources that contributed to the emergence of disease concurrently in different premises under the same ownership. Surprisingly, frequency of direct or indirect contacts did not differ between case and control herds. This also applies to frequency of feed delivery, which, although statistically significant, was driven by a single highly influential point, which in itself did not align with a biological rationale for spread through feed deliveries. Two risk factors that remained stable were herd PRRSv status and directional spread in a western direction.

Tetracycline use and selection of virulent enterotoxigenic Escherichia coli

Posted in: Ontario Pork, Pork Insight Articles by admin on August 16, 2010 | No Comments

In the last decade in Ontario a new strain of E. coli (ETEC) of the serogroup O149 has been causing severe diarrhea in piglets after weaning. This new strain contains pTENT2 which encodes for tetracycline resistance and virulence factors that were absent from previous O149 ETEC strains. This suggests that the increased virulence of the new ETEC is caused by the pTETN2 plasmid and that the use of tetracycline may select for this strain. The objectives of this project was to develop methods to identify and detect this strain, to generate mutants without the new pTENT2 plasmid, and to compare the behavior of the ETEC strain with and without pTENT2 with and without tetracycline in the feed in an animal model for postweaning diarrhea. E. coli O149 strains with and without the pTENT2 plasmid were generated. They were used to infect weaned piglets fed with and without tetracycline. The severity of the treatments was assessed in the piglets.No statistical difference was detected between groups that received the modified ETEC strains. Some variations were found, but studies with larger numbers need to be carried out to confirm the significance.

Early Weaning Reduces Small Intestinal Alkaline Phosphatase Expression in Pigs

Posted in: Ontario Pork, Pork Insight Articles by admin on August 14, 2010 | No Comments

This study was conducted to determine the effect weaning has on intestinal alkaline

phosphatase (IAP) activity. IAP is important for enteric health of the growing pig, playing roles

in immune health, intestinal health, digestion, and fat absorption. 12 piglets were weaned at ten

days old and put on standard commercial weaning diet and 12 piglets remained suckling with the

sow as the control treatment. Overall, weaning decreased IAP affinity by 26% and maximal enzyme

activity by 22%.  The main effect was seen in the jejunal region becasue the jejunum expresses 84-86%

of the total gut mucosal IAP activity. Weaning decreased the amount of IAP associated with the

proximal jejunal apical membrane by 64% and proximal jejunal IAP mRNA by 58% which was

associated with a decrease in the abundances of cytoplasmic (27%) and nuclear (29%) IAP caudal-

associated homeobox transcription factor 1. In conclusion, weaning decreased the amount of

IAP available in the pigs gut to facilitate gut and immune health. This may, in part, contribute

to the growth check and increased susceptibility to gastro-intestinal disease in early weaned pigs.

Relationship between estimated finishing-pig space allowance and in-transit loss in a retrospective survey of 3 packing plants in Ontario in 2003

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A retrospective survey to determine the effect of space allowance on in-transit losses of  finisher pigs in summer temperatures in June, July and August 2003. Both 2- and 3-tiered  trailers were considered that transported greater than 130 pigs to 3 main Ontario packing plants processing 76% of all Ontario market hogs. Packer data was combined with daily in-transit loss data to determine the number of pigs that were transported on that trailer and space allowance was determined from the trailer’s capacity and the number of pigs transported. Environmental temperature and relative humidity data was provided by 2 local Ontario weather stations and were considered on a hourly basis. As environmental temperature increased, in-transit losses  increased. As space allowance decreased, in-transit losses increased when the temperature was  constantly below 21°C however by a lesser amount than was seen with temperature. Overall, it was found that temperature had a greater affect on piglet in-transit losses than space allowance   however increasing space allowance allows pigs to cool more efficiently and will therefore  decrease pig in-transit losses.

Greater Availability of Amino Acids in Feedstuffs for Sows Compared to Growing Pigs

Posted in: Ontario Pork, Pork Insight Articles by admin on August 13, 2010 | No Comments

Recent data suggests that gestating sows have a greater capacity to digest dietary protein than growing pigs and thus different values for amino acid availability should be used when formulating sow diets. The MA of threonine in corn and barley in six gestating gilts (146 ± 4 kg BW) was determined using the indicator amino acid oxidation technique. A paired study using six growing pigs (146 ± 4 kg BW) and corn was conducted to allow a direct comparison between a) determined MA values and published TID values for growing pigs and b) the determined MA for sows and growing pigs. Pigs were fed reference diets with increasing synthetic THR from 50 – 80 % of requirement; all other nutrients were provided in excess. Test ingredient diets were formulated to 80 % of requirement by inclusion of corn or barley. On collection day, L [1-13C] and L [1-14C] phenylalanine (sows and growers, respectively) was given orally in eight ½-hourly meals and expired 13CO2 and 13CO2 was quantified. The Mixed model in SAS was used to determine the change (slope) in indicator oxidation per gram of total dietary THR from reference and test diets. The MA of THR was calculated as the slope for THR from test diets divided by the slope for THR from reference diets.  The MA method gives results not different from TID. The bioavailability of amino acids in feedstuffs is greater in sows than in growing pigs.

The Requirement for Threonine in Early and Late Gestation in Sows

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This study aims to determine the requirement for Threonine in early and late gestation in sows. The THR requirement in early (25-55d) and late (80-111d) gestation was determined by indicator amino acid oxidation in eight sows fed THR from 20 % to 120 % and from 60 % to 180 % of NRC (1998) estimated requirements in early and late gestation, respectively. L [1-13C]phenylalanine was given orally in eight ½-hourly meals as indicator AA and expired 13CO2 was quantified. The nonlinear Mixed model in SAS was used to determine the THR requirement for each period by breakpoint analysis. Sows responded differently to increasing levels of dietary THR in early and late gestation. Breakpoint analysis resulted in a THR requirement of 4.9 g/d in early gestation (R2=0.71) and 12.3 g/d in late gestation (R2=0.58). The current recommended THR intake during gestation is 10 g/d. These results support previously reported data that there is a greater than 2-fold increase in THR requirement in late gestation. Reducing AA content in sow diets up to 80 d gestation followed by higher AA content in late gestation may substantially reduce feed costs. Phase feeding during gestation may also improve sow reproductive performance by more closely meeting AA demand in late gestation. Current practices of feeding a single AA level during gestation results in negative impacts on sow body condition in late gestation due to deficient AA intake.

Dietary Lysine Requirement is Greater in Latethan in Early-Gestation in Sows

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The objective of this study was to determine the lysine requirement of a population of 2nd and 3rd parity sows in early- (day 24 – 45)
and late- (day 86 – 110) gestation. Pregnant Hypor Hybrid (Hypor Inc) sows (n=7; 185.7±9.6 kg BW) were  adapted to individual intakes of a semi-synthetic diet containing 14.0 MJME/kg. Each sow received 6 different test diets, in random order, from 60 –150% of the requirement suggested by NRC (1998) in early- and from 60 –185% of the requirement suggested by NRC (1998) in late-gestation. Actual dietary lysine intakes ranged from 7.5 – 19.3 g/d in early- and 8.1 – 23.7 g/d in  late-gestation. Differences between the dietary lysine requirement for earlyand late-gestation was determined by measuring oxidation of the indicator amino acid L-[1-13C]-phenylalanine (Phe) during a primed-constant oral infusion. The average number of piglets born alive was 13.7±1.9, but ranged from 4 to 20. The average piglet birth weight was 1.5±0.1 kg. Sows gained 600 g/d from breeding and weighed 258.8±8.3 kg before farrowing. Breakpoint analysis of Phe oxidation indicated that the lysine requirement of 2nd parity sows was 13.1 g/d and 18.7 g/d in early- and late-gestation, respectively. For 3rd parity sows, the dietary lysine requirement was 8.2 g/d and 13.0 g/d for early- and late-gestation, respectively. Phase feeding at least two diets would improve productivity by more correctly providing the necessary nutrients for the growth of the placenta, the piglets, and the mammary gland.

Dietary Lysine Requirement is Greater in Latethan in Early-Gestation in Sows

Posted in: Ontario Pork, Pork Insight Articles by admin on August 12, 2010 | No Comments

The objective of this study was to determine the lysine requirement of a population of 2nd and 3rd parity sows in early- (day 24 – 45) and late- (day 86 – 110) gestation. Pregnant Hypor Hybrid (Hypor Inc) sows (n=7; 185.7±9.6 kg BW) were adapted to individual intakes of a semi-synthetic diet containing 14.0 MJME/kg. Each sow received 6 different test diets, in random order, from 60 –150% of the requirement suggested by NRC (1998) in early- and from 60 – 185% of the requirement suggested by NRC (1998) in late-gestation. Actual dietary lysine intakes ranged from 7.5 – 19.3 g/d in early- and 8.1 – 23.7 g/d in late-gestation. Differences between the dietary lysine requirement for early and late-gestation was determined by measuring oxidation of the indicator amino acid L-[1-13C]-phenylalanine (Phe) during a primed-constant oral infusion. The average number of piglets born alive was 13.7±1.9, but ranged from 4 to 20. The average piglet birth weight was 1.5±0.1 kg. Sows gained 600 g/d from breeding and weighed 258.8±8.3 kg before farrowing. Breakpoint analysis of Phe oxidation indicated that the lysine requirement of 2nd parity sows was 13.1 g/d and 18.7 g/d in early- and late-gestation, respectively. For 3rd parity sows, the dietary lysine requirement was 8.2 g/d and 13.0 g/d for early- and late-gestation, respectively.  The dietary requirement for lysine in gestation was greater than previously reported by NRC (1998). Phase feeding at least two diets would improve productivity by more correctly providing the necessary nutrients for the growth of the placenta, the piglets, and the mammary gland.

Expression of chemokine decoy receptors and their ligands at the porcine maternal–fetal interface

Posted in: Ontario Pork, Pork Insight Articles, Production by admin on August 3, 2010 | No Comments

Successful pregnancy requires coordinated maternal–fetal cross-talk to establish vascular connections that support conceptus growth. In pigs, two waves of spontaneous fetal loss occur and 30–40% of conceptuses are lost before parturition. Previous studies associated these losses with decreased angiogenic and increased inflammatory cytokines. Chemokines, a sub-category of cytokines, and decoy receptors control leukocyte trafficking, angiogenesis and development. The availability of chemokines is regulated by three non-signalling decoy receptors: chemokine decoy receptor (D6), Duffy antigen receptor for chemokines (DARC) and Chemocentryx decoy receptor (CCX CKR). We hypothesized that the expression of these receptors and their chemokine ligands regulate the porcine pregnancy success or failure. Here, we describe for the first time the transcription and translation of all three decoy receptors and several chemokine ligands in endometrium and trophoblast associated with healthy and arresting conceptuses at gestation day (gd) 20 and gd50. Among decoy receptors, transcripts for DARC were significantly reduced in endometrium, whereas that for CCX CKR were significantly increased in endometrium and trophoblast at gd50
arresting compared with healthy sites. However, western blot analysis revealed no differences in decoy receptor expression between healthy and arresting tissues. Transcripts for decoy receptor ligands CCL2, CCL3, CCL4, CCL5, CCL11, CCL19, CCL21, CXCL2 and CXCL8 were stable between healthy and arresting littermates. Quantification by SearchLight chemiluminescent protein array confirmed ligand expression at the protein level. These data indicate that decoy receptors and ligands are expressed at the porcine maternal–fetal interface and dysregulation of decoy receptor (DARC and CCX CKR) transcripts occurs at sites of fetal arrest.

Effect of pain relief at piglet castration and farrowing on welfare and performance of piglets

Posted in: Ontario Pork, Pork Insight Articles, Welfare by admin on June 14, 2010 | No Comments

This study tests the effects of analgesia on piglets to see if it reduces pain and has any impact on growth performance. Two trials were carried out, the first was done on piglets, where some would receive analgesia before castration and some wouldn’t. Then the were tracked to see how they differed in mortality rate and average daily weight gain to weaning. The second trail involved giving the analgesia to the sow before and during farrowing and then stillbirths, growth rate to weaning and pre weaning mortality was recorded. For trial one there was no difference in ADG or mortality between the groups, and a subjective evaluation of the piglets pain during castration found no variation between groups. For the second trial there was no significant difference between groups for pre weaning mortality, number of piglets crushed, ADG or stillbirths. The use of analgesia increases the time of castration and has costs associated with purchasing the drugs. There was no difference found between pigs who were on the drugs and those that were not, the use of analgesia was found to have no benefit to producers.