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Prairie Swine Centre is an affiliate of the University of Saskatchewan
Prairie Swine Centre is grateful for the assistance of the George Morris Centre in developing the economics portion of Pork Insight.
Financial support for the Enterprise Model Project and Pork Insight has been provided by:
Porcine Reproductive and Respiratory Syndrome Virus (PRRSV): the Disease That Keeps Bugging Us
Posted in: Pork Insight Articles, Production by admin on April 1, 2008 | No Comments
This paper gives an overview on the current PRRSv situation. The global distribution of PRRSv has changed, with new cases spreading over Africa, but Chile being close to eradicating the disease. There has also been a new recognition of the economic impact PRRSv has on finisher pigs. The impact is only expected to grow, as feed costs have risen and PRRSv can have a large impact on ADG and feed efficiency. As well, PRRSv can affect import and export of raw pork and live pigs. There have been advancements in prevention methods including biosecurity protocol for people and transport trucks, and air filtration system evaluations. Control of the virus involves developing herd immunity and depopulation, although a vaccine is available it is still not fully effective. The infection dose has been calculated for various transmission methods, and knowledge on transmission methods and virus tolerance have been increased. Research on transmission through aerosols is still ongoing. Diagnostic procedures for collecting samples have improved, and PCR diagnostics will continue to improve as well. Understanding PRRSv will help us identify, control, and eventually eliminate it from our herds.
New Opportunities for Reproductive Management
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Reducing litter size for replacement gilts and boars could possible increase reproductive performance, but the goal is different for gilts than for boars. Gilts are mainly culled for failure to reproduce, and is called involuntary culling. Sows have peak reproductive performance between parities 3 and 6, so reproductive improvement would involve improving reproductive success over a longer time span. Boars are culled after 12-18 months because a new generation is starting, and it is voluntary culling. So for boars, increasing reproductive performance over a short time span is the goal. Smaller litters may allow replacement piglets reduced competition and more nutrients, and as the sexual organs are still developing at this point it could positively influence later performance. The size of litter and day of boar exposure was tested for the effect on sow longevity, with the measure being which sows were still in the herd after their third parity. Smaller litters and earlier boar exposure (day 140) resulted in 26% more sows reaching their third parity, and a 10% increase in farrowing rate. Being raised in smaller litters also increased the number of pigs per litter by 0.5. The results show early management has a long-term reproductive effect on gilts and, although consistent boar exposure may not be possible, reducing litter size for replacement gilts is commercially feasible. Boars raised in small litters had a significantly reduced training period for semen collection than those raised in large litters, indicating increased libido. Small litter boars also had increased testicular size, numbers of spermatozoa, and appear to be more fertile from siring results from heterospermic insemination data. So, similar to gilts, litter size has an impact on a boar’s reproductive performance, and reducing the litter size through cross-fostering is a commercially feasible strategy.
Is There an “Optimum” Production System?
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A theoretical optimum production system in North America would take into account financial risks, including currency exchange due to the connection between Canada’s industry and the US. The current production system has a large amount of Canadian feeder pigs exported to the US because many farrow-finish facilities are switching to wean-finish. Avoiding farrowing barns saves the cost of committing to a sow herd, and the problems associated with it. High regulatory costs have prevented small or medium barn expansions in many cases, and favour large barns. To work towards an optimum system the right people need to be hired, and the pig flow needs to be matched with the facility. Lenders also shape the system, as they are more reluctant to invest in separate nursery and finishing barns than they are to invest on a wean-finish facility. To minimize size variation and for biosecurity, these facilities usually prefer pigs all from one source and 1-2 weeks in age of each other. For a farrowing facility to supply this number, they would need to have about 6000 sows. Batch farrowing is an option, but it usually requires an all-in all-out system with groups from different sources separated if possible. The maximum number of farrowing sources is usually 2, with each site having around 1200 sows. The optimum system has to consider the pig flow, and the various sizes of the facilities involved. Therefore, the optimum system should constantly aim to minimize all aspects of variation – like litter size, weaning weight and age, and market weight – and include a team of advisors to consider all aspects of a decision.
Quality Control of Extended Boar Semen
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Extended boar semen should regularly undergo testing to ensure producers are receiving a safe and effective product. Quality checks can involve analysing sperm motility, morphology, concentration, and numbers per dose, as well as dose volume. Samples should be randomly selected, and high producing studs should have 51/200 samples tested and low producing studs 27/200 samples. Alternatively, samples can be sent on a predetermined weekly, biweekly, or monthly schedule. The samples should be shipped to the laboratory using standard shipping protocol. On arrival the temperature of samples should be taken, volume measured, spermatozoa motility assessed, concentration and number of spermatozoa per dose counted, and morphology evaluated. Morphology can be evaluated by gross evaluation under a microscope, which is usually the technique used for pooled semen, or a detailed differential evaluation can be done if there is suspected sub-fertility. Semen can easily become contaminated by bacteria during collection, so bacterial cultures can be performed using a blood agar culture plate. If bacteria are found, they should be identified and antibiotic sensitivity performed, and the cause of contamination can also sometimes be identified. Regular assessments of boar semen will help identify areas to improve, and reassure producers of the quality they are receiving.
Applying Reproductive Technologies in Practise
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When conducting on-farm trials for a study it is important that the duration is long enough, enough animals are used, and a control group is included. Basic studies involve fewer animals and controlled conditions, whereas applied studies are on-farm (or “in field”) and have more animals under real life conditions. The duration for on-farm reproductive studies depends on whether boars or sows are being studied. For studies on boars, usually technology is developed to improve quantity or quality of sperm. It takes around seven weeks for sperm to develop, and any effect from a treatment to be seen. The sows’ reproductive cycle is more complex than the boars, and the length of the trial will depend on which part of the cycle is being targeted. Implementing a treatment to the entire herd and comparing before and after results is not recommended because herd conditions are constantly changing, and confounding variables have a high chance of being introduced. Deciding the number of animals used in the study will depend on how large of an effect is needed by the new technology, the current herd performance, the herd variation, and the level of confidence wanted for results. Expensive technologies will likely require a greater improvement in results to be routinely used than an inexpensive, or labour reducing technology. Applied studies allow new technology to perform in a commercial setting, and obtaining accurate results relies upon choosing proper duration and numbers, and use of a contemporary group.
Optimum Solutions for Grower-Finisher Pigs
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Watson® is a web-based software application designed to help producers make decisions. It shows cause-and-effect responses that change with the production environment, shows the financial impact of the change, and recommends farm-specific nutritional or financial strategies. The nutritional strategies can involve nutritional requirements, optimizing nutrient distribution, the use of ractopamine, and feed budgets. The program can incorporate current feed prices, estimate the impact of carcass variation, and determine optimum market weight under a set series of conditions. The Watson® system integrates nutrition and financial information to help producers make decisions in a volatile market.
Effects of oral administration of sodium citrate or acetate to pigs on blood parameters, postmortem glycolysis, muscle pH decline, and quality attributes of pork
Posted in: Production by admin on January 1, 2008 | No Comments
This study determines the effect of oral administration of sodium citrate (CIT) or acetate (ACE) to pigs on blood parameters, postmortem glycolysis, pH decline, and quality attributes of pork. It was found that no significant inhibition of the PFK enzyme by orally administered CIT or ACE; however, the PFK glycolytic metabolite data analysis indicated that PFK was a main regulatory enzyme in postmortem muscle.
Effect of soluble and insoluble dietary fiber on embryo survival and sow performance
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Two experiments were conducted to evaluate the effects of soluble (SF) and insoluble (ISF) dietary fiber during gestation on embryo survival and sow performance. It was concluded that the inclusion of SF and ISF in gestation diets did not affect litter size. Sows fed the HS+HIS diet had a greater ADFI and lost less birthweight during lactation than sows fed C. Feeding gestating sows increase levels of both SF and ISF from day 2 after breeding to day 109 of gestation, did not increase litter size.
Sow line differences in heat stress tolerance expressed in reproductive performance traits
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The objectives of this study were 1)
to investigate if there were differences in the relation
between temperature and reproductive performance
traits in 2 different sow lines, a Yorkshire line producing
mainly in temperate climates and a Large White
line producing mainly in warm climates, and 2) to determine
the upper critical temperature (UCT) for the
reproductive performance of these 2 lines. Sows are
exposed to heat stress when temperature exceeds the
UCT of the thermo-neutral zone. Data included 32,631
observations on reproductive performance from 11,935
sows on 20 farms in Spain, collected from 2003 to 2005.
Sows belonged to 2 different purebred sow lines, named
D (Yorkshire sow line, producing mainly in temperate
climates) and I (Large White sow line, producing
mainly in warm climates). Only first insemination records
per parity were used and were combined with the
maximum outside temperature at day of insemination.
Upper critical temperatures were studied for 3 reproduction
traits: farrowing rate (0 or 1), litter size (range
from 1 to 25), and total number of piglets born per first
insemination (combination of farrowing rate and litter
size, range from 0 to 25). Data were corrected for fixed
effects, which included parity, service sire, and an interaction
between farm and year. Corrected data were
used as observations in the models to study the effect of
outside temperature on reproductive performance. Two
models were compared for goodness of fit: a linear regression
model and a plateau-linear model with the plateau
representing the thermo-neutral zone and a linear
decrease above that zone. Farrowing rate of I-line sows
was not affected by temperature. For litter size and
total number born per first insemination of I-line sows
no UCT could be estimated. These traits were linearly
affected by temperature. For all 3 reproduction traits of
the D-line the best model was the plateau-linear model;
the UCT for the D-line sows was estimated to be 19.2°C
for farrowing rate, 21.7°C for litter size, and 19.6°C for
total number born per first insemination. The decrease
in reproductive performance of I-line sows with increasing
outside temperature was less than in D-line sows.
From this study it can be concluded that there are
differences in heat stress tolerance between sow lines
as measured by the differences in reproductive performance.
These differences are an indication of genetic
differences in heat stress tolerance in sow lines.
Effects of adding fibrous feedstuffs to the diet of young pigs on growth performance, intestinal cytokines, and circulating acute-phase proteins
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The consumption of dietary fiber has been shown to regulate systemic and intestinal inflammation. An inverse relationship between fiber intake and circulating acute-phase proteins has been observed in humans (Basu et al., 2006; Ma et al., 2006). Mechanistically, dietary fiber may alter the inflammatory response through regulating the expression of cytokines. Indeed, recent studies have shown that supplementing pig diets with a combination of 4 sources of dietary fiber increased colonic IL-6 expression (Pie et al., 2007). To date, there are no published data on the effects of different fiber types on the expression of cytokines or whether feeding fiber alters markers of systemic inflammation in pigs. Inflammation via the action of cytokines has been found to regulate pathways involved in protein synthesis. Endotoxin challenge decreases the activation of S6 kinase (S6K1), a protein involved in protein translation initiation (Ruvinsky and Meyuhas, 2006) in skeletal muscle (Kimball et al., 2003; Lang and Frost, 2004). However, piglets infected with rotavirus enteritis have an increased level of activated S6K1 in intestinal tissue (Rhoads et al., 2007). There is little data available exploring the effect of dietary fiber on cytokine expression and subsequent effects on anabolic pathways and piglet growth. Therefore, the objectives of this study were to determine the effects of different types of dietary fiber on pig growth, intestinal cytokine expression, and markers of systemic inflammation. Intestinal tissue DNA and protein content and the activation of intestinal S6K1 were also determined. Pigs (n = 120; initially 5.2 kg and 24 d of age) were randomly assigned to diets containing 1 of 4 fiber sources: 1) control diets containing no added fiber source, 2) diets containing 7.5% distillers dried grains with solubles (DDGS), 3) diets containing 7.5% soybean hulls, or 4) diets containing 7.5% citrus pulp. The experimental diets were fed for 4 wk in 2 phases (phase 1, wk 1 and 2; phase 2, wk 3 and 4). Intestinal tissue samples, liver samples, and blood samples were collected from a subset (n = 24; 6 pigs/treatment) of the pigs on day 7, and blood samples were collected from another subset (n = 24; 6 pigs/ treatment) of pigs on day 28 of the experiment. Dietary treatment had no effect on ADG, ADFI, or G:F throughout the experiment. Likewise, pig BW variability (CV), plasma IGF-I, or the plasma concentration of the acute phase proteins, á1-acid glycoprotein, C-reactive protein, and haptoglobin, were not affected by dietary treatment. Real-time RT-PCR analysis revealed that on d 7, pigs fed DDGS had a greater (P < 0.05) relative abundance of the mRNA encoding IL-6, IL-1â, and IL-10 in ileum tissue than pigs fed all other diets. Diets containing DDGS had no effect on the relative abundance of tumor necrosis factor á or interferon-ã mRNA in ileum tissue on d 7. The d-7 mRNA expression of cytokines was not altered in jejunum, colon, or liver tissue by dietary treatment. Intestinal tissue protein content or jejunum and ileum DNA concentrations were not affected by diet. Western blot analysis found no effect of dietary treatment on the activation of S6 kinase in jejunum, ileum, or colon tissue on day 7. These results indicate that feeding 7.5% of a fiber source as DDGS, soybean hulls, or citrus pulp does not affect growth performance or circulating markers of inflammation in weanling pigs and that feeding DDGS increases the expression of both pro inflammatory and anti-inflammatory cytokines in intestinal tissue.