Isoleucine Requirement for Pregnancy in Adult Sows

Posted in: Ontario Pork, Pork Insight Articles by admin on August 13, 2013 | No Comments

Pregnant adult sows show little maternal growth so that accelerated conceptus growth in the 3rd trimester can cause large differences in nutrient requirements between early (EG) and late (LG) gestation. The objective of this study was to determine the Ile requirement in EG (d 37 to 61) and LG (d 89 to 109) using the indicator amino acid oxidation (IAAO) method. Seven 4th parity sows received 6 diets each based on corn, corn starch and sugar in both EG and LG at a constant intake of 2.5 kg/d. Diets in EG contained Ile at 20, 40, 60, 80, 100 and 120 % of the current Ile requirement and 60, 80, 100, 140, 160 and 180% in LG. Sows were fed 2 mg/(kg BW·h) of L[1-13C]Phe over 4 h in 8 ½-hourly meals. Requirements were determined as breakpoints in IAAO using 2-phase nonlinear models. Sows, 232.0 ±4.9 kg at breeding, gained 19.1 ±4.4 kg in gestation and had litters of 17.7 ± 0.75 piglets weighing 22.6 ± 0.87 kg. The Ile requirement was greater in LG than EG (P = 0.001) at 3.6 g/d vs. 9.7 g/d. The increased (P = 0.001) in Phe retention (-0.48±0.55 g/d in EG vs. 3.34 ±0.55 g/d in LG) was caused by accelerated fetal growth. Energy and lipid retention decreased (P < 0.003) from EG to LG and were negative in LG. This indicates that Ile requirements were driven mainly by maintenance in EG and by fetal growth in LG. Both Ile and energy intake must be increased in LG but the greater change in Ile than energy requirement shows that amino acid supply is more critical in LG for adult sows.

Effects of Handling Procedures and Transport Vehicle Design on the Welfare and Meat Quality of Pigs

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The objectives of this project were to study stressors experienced by market pigs during handling and transport, to identify components of these stressors that can be modified, and to assess whether modifying these components can reduce stress and/or improve the ability of pigs to recover. This researched showed that the use of double deck hydraulic trailers resulted in less stress and better meat quality compared to pot belly trailers, likely due to the absence of internal ramps and reduced handling stress at loading and unloading. In addition, pigs spent more time standing during transport in winter, likely to conserve heat by minimizing contact with the trailer floor. Heart rate and internal body temperatures were also higher in winter, suggesting increased metabolic rate. In eastern studies, hot summer temperatures and shorter transport times resulted in increased stress on pigs and higher levels of PSE meat traits, while in western studies, long transport times in winter resulted in greater stress compared to summer conditions. Indeed, it was shown that pigs transported long distances in winter showed increased drinking in lairage, indicating dehydration and produced more hams with RSE and DFD meat characteristics. Lastly, there is significant variation in temperature and humidity conditions between compartments on all trailers studied, with upper rearward compartments having lower temperatures and central front compartments being warmer. Results of this research have implications for industry, regulators and for future research to improve transport conditions.

Identifying the cause of death and factors associated with hogs that perish in-transit: A pilot project at 2 Ontario packing plants.

Posted in: Ontario Pork, Pork Insight Articles, Production by admin on June 26, 2013 | No Comments

The cause of death for pigs in transit is usually assumed to be heat exhaustion or stress, and a full autopsy is rarely performed. This study autopsied pigs that died, or would be euthanized after transport, from two packing plants. 84% of the autopsies showed abnormal hearts, and so from that point on a procedure for examining the hearts was put into practice, as well as the full autopsy. The hearts were stored in formalin for 24 hours, weighed, sectioned, and examined by the same project pathologist. The lesions observed on the affected hearts were classified as Hypertrophic Cardiomyopathy like Lesions (HCML) due to the similarity to the lesions found in humans, dogs, and cats with HCM. To determine the prevalence of  HCML in the general pork population, 51 additional hearts from pigs that did not die in transit were examined. It was found 50% of the control hearts also had lesions, but were not pronounced enough to cause heart failure when under the stress of transport. Since HCM is a genetic heart condition, an attempt was made to survey the genetic lines from farms that produced pigs with heart lesions, but there were not enough participants to provide information. Future work might look at the genetic lines contributing to HCML occurrence in pigs, and then in-transit deaths could be reduced by selectively breeding to improve heart condition. At this point, temperature control and reducing stress can help reduce in-transit deaths by avoiding triggering heart failure in susceptible animals.

Immune response phenotype of allergic versus clinically tolerant pigs in a neonatal swine model of allergy

Posted in: Ontario Pork, Pork Insight Articles by admin on April 8, 2013 | No Comments

The prevalence of childhood food allergy and the duration of these allergies, particularly those considered to be transient, like egg and milk allergy, are increasing. The identification of allergic individuals using minimally invasive, non-anaphylaxis-threatening methods is therefore of increasing importance. In this experiment, correlates were sought of an allergic immune response (IR) phenotype in pigs. Using pigs pre-treated with heat-killed bacteria or bacterial components before allergic sensitization with the egg white protein ovomucoid (Ovm), differences were determined in IR phenotype of pigs in the categories treated-allergic, treated-tolerant, control-allergic (CA) and control-tolerant. Phenotype was established by measuring immunoglobulin (Ig)-associated antibody activity (AbA), cytokine profiles and the proportion of blood T-regulatory cells (T-regs) and observing late-phase allergen-specific skin tests (ST). Although 100% of pigs became sensitized to Ovm, only 33% of pigs had clinical signs of allergy after oral challenge with egg white. Pigs without clinical signs were classified as clinically tolerant. Sixty-seven percent of allergic pigs had a positive, late-phase ST classified as very strong or strong, while 84% of clinically tolerant pigs did not have late-phase ST. Treated-allergic pigs and CA pigs had greater total antibody IgG (H + L), IgE and IgG1 AbA than clinically tolerant pigs. Cytokine profiles of allergic pigs and the proportion of circulating T-regs, did not differ significantly between allergic and clinically tolerant pigs. Therefore, measurement of allergen-specific IgG, IgG1 and/or IgE activity and evaluation of late-phase ID ST may be useful in identifying allergic IR phenotypes in swine models of food allergy, which may be extended toward human use.

Effects of Handling Procedures and Transport Vehicle Design on the Welfare and Meat Quality of Pigs

Posted in: Ontario Pork by admin on September 24, 2012 | No Comments

The objectives of this project were to study stressors experienced by market pigs during handling and transport, to identify components of these stressors that can be modified, and to assess whether modifying these components can reduce stress and/or improve the ability of pigs to recover. Our overall goal was to reduce the stress associated with marketing and thereby improve animal welfare, reduce death losses, and improve meat quality.  Stressors assessed included handling during loading and unloading, the environmental conditions on the transport vehicle in summer and winter and duration of travel. The stress response of pigs was assessed using behavioural and physiological parameters, as well as carcass and meat quality characteristics.

Pathogen die-off rates following manure application under Ontario field conditions

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A field study to examine the decline of manure-derived pathogens under field conditions was established in the spring of 2011.  Sentinel chambers were used to facilitate the study of “captive” populations of organisms within field sites without the confounding losses due to runoff-induced movement from the sites.  The overall objectives of the study included the following.

1. Measurement of die-off rates of manure-derived organisms under field conditions following spring, late summer and fall manure application using the sentinel chamber technique.
2. Comparison of these die-off rates to population changes in the bulk soil which result from both die-off and transport mechanisms.
3. Assessment of the effect on pathogen survival of manure surface application versus incorporation, and application times (spring, summer and fall).
4. Measurement of concurrent changes in nutrient (N, P) levels at the same field sites to assess the contradictory impacts on nutrient and pathogen risk management.
5. Comparison of measured die-off rates to pre-planting and pre-harvest waiting times for food safety
6. Provision of the information for manure management recommendations to
   1. reduce surface and groundwater impacts from manure application, and
   2. improve food safety by reducing the risk of food-borne illness resulting from pathogen contamination of irrigation water or soils in which food crops are grown.

Environmental Compliance Costs and the Competitiveness

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This study measured the compliance cost of the current and possible future nutrient management regulations on pig production facilities in Ontario. Two farm types were examined: farrow to finish and finishing facilities. Three farm sizes were considered for each category:  a small farm with 900 pigs produced per year, a medium farm with 4,500 pigs produced per year and a large farm with 10,500 pigs produced per year. Each scenario was then tested with uniform manure application and optimal manure application that varied application rates by crop type based on plant nutrient needs. These scenarios were then examined under nutrient management regulations from the Nutrient Management Act (2002) and the Clean Water Act (2007).   The Nutrient Management Act includes two separate calculations for determining the maximum manure application rate. The crop nutrient requirement calculation bases the maximum manure application rate on the amount of phosphorus each crop requires and then allows for additional phosphorus application of 15.15lbs per acre. The second calculation to determine the maximum nutrient application rate involves the amount of phosphorus removed by the crop. This calculation allows for manure application to meet the amount of phosphorus the crop will remove at harvest plus 69.5lbs of phosphorus per acre. The Clean Water Act results assumed that regulations would restrict the nutrient application rate to 115% of the crop requirements of nitrogen and phosphorus. The medium and large production facilities were then subjected to sensitivity analysis of the soil phosphorus test as well as changes in the nutrient application rate allowable under the Clean Water Act. Lastly, the medium and large scenarios were also subjected to changes in the prices of inputs and outputs for crops and pigs to determine the sensitivity to prices.

Use of controlled ovulation and seminal plasma on sow fertility to insemination of cryopreserved sperm

Posted in: Ontario Pork, Pork Insight Articles by admin on August 22, 2012 | No Comments

When boar semen is frozen and thawed (FT) the fertility rate of the insemination is lower than fresh semen; fewer sperm live at thawing and there is a shorter lifespan of surviving sperm in the female reproductive tract. This project looked at incubating thawed semen in seminal plasma (SP) to see how it effected sperm viability and mortality in virtro. Also how SP effected in vivo sow fertility to double conventional AI, or single intrauterine AI. For the in vitro test, FT sperm were thawed and incubated for 4 hours with either 0%, 10% or 50% SP. Sperm populations were examined for viability and mortality every hour they were incubated for. Incubation in 50% SP increased percentages of live sperm and sperm motility at all time points compared to incubation in either 0% or 10% SP. For the in vivo test 82 sows were used, sows received 3 x 109 live fresh-extended sperm or FT sperm thawed in 80 mL BTS extender or 3 x 109 live FT sperm thawed in 80 mL BTS containing 50% SP (FT-SP). Sows who received fresh semen had the highest pregnancy rate followed by the FT-SP group, the FT group having the lowest rate. Farrowing rates were not different. In the in vivo single intrauterine AI test, 97 sows were inseminated at 36 h after pLH with 3 x 109 live FT sperm with or without 50% SP, or 3 x 109 fresh sperm. Compared to controls, insemination of FT-SP decreased farrowing rate but litter sizes were not different from controls. These results confirm that there is an adverse effect of inseminating FT sperm on sow fertility but using sperm that has been incubated in 50% SP can partially alleviate these negative effects.

Case-Control Study of Porcine Circovirus Type 2 – associated disease outbreaks in Ontario

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This study was a case-control observational study using 25 farms that had a 2 year history of clinical Porcine Circovirus type 2 (PCV2) associated disease (PCVAD) and also 25 matched farms that had no history of the virus. A survey was taken to find the risk factors associated with the disease and samples were taken to test for what type of circovirus was present. All viruses from case or control farms were identified as RFLP 321. Vaccination has proven to be very effective in containing the disease in case farms and it was more difficult to find virus on vaccinated farms. Lesions consistent with PCVAD were found on control farms, suggesting that a vaccine might be appropriate in these herds also. The main result of this work was that the new strain of virus that prevailed 2 years ago, which appears to be a severe disease of grower-finisher pigs, is now in the majority of swine herds in Ontario. There may potentially be other reasons as to why the disease suddenly became a cause of high mortality in grow-finish pigs.

Effect of addition of seminal plasma to thawed semen on sow fertility

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The use of frozen-thawed semen results in much lower fertility rates than the use of fresh semen. Although frozen semen has several benefits, such as bio-security, in that frozen semen can be tested for things like the PRRS virus so the inseminated herd is not infected. It has been suggested that seminal plasma can improve frozen-thawed semen performance. Also new timing techniques at ovulation and delivery of the seaman to the uterus instead of the oviducts, which is traditionally done, can help raise the fertility rates of frozen-thawed semen. These methods have potential to improve the chances of fertilization. Four separate experiments were carried out examining these methods by themselves and in combination. It was found that there was no advantage to adding seminal plasma to the semen, leading researchers to believe that freezing semen causes a degree of injury. Also the timing of insemination and process of insemination did not result in improved fertilization rates. More research must be carried out to be able to achieve full potential from frozen-thawed semen.