Interactive effect of ractopamine and dietary fat source on pork quality characteristics of fresh pork chops during simulated retail display

Posted in: Meat Quality by admin on January 1, 2008 | No Comments

This study used 216 crossbred pigs to test the effect of ractopamine (RAC) and dietary fat sources on the performance of finishing pigs, pork quality characteristics, and quality of LM chops during a 5 day simulated retail display. It was concluded that neither RAC nor fat source altered LM cooking losses and shear force values. Feeding 10 mg/kg of RAC will improve rate and efficiency of gain, carcass composition, and LM quailty. It was also concluded that performance and carcass composition, as well as quality during the 5 days of retail display, were similar when pigs were fed either diet. (Beef tallow or Soybean oil)

Implementation of Mandatory Country of Origin Labeling (MCOOL) in the Pork Industry

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The impetus for MCOOL came from northern plains beef producers as far back as the mid–1990s. The stated idea was that U.S. consumers deserve full information about the foods that they purchase and eat—an idea that is difficult to argue with. The underlying concerns, however, were growing imports of beef, pork, cattle and hogs from Canada and their perceived negative impact on U.S. markets. MCOOL is far less onerous for the pork industry than for the beef industry
for several reasons. First, Canada is the only source of imported pigs and market hogs. No hogs are presently
imported from Mexico due to animal disease restrictions. Second, all–in all–out production systems
keep pigs in defined, closed groups from early in life until slaughter in order to prevent the introduction of
disease. There is little or no comingling of animals as there is in the beef industry. This means that the origin
of an individual animal is the same as the origin of its group. Whether U.S. pig production increases
depends on the ultimate reaction of consumers, primarily to the multicountry labels. U.S. consumers
have a very positive view of things Canadian, though, so the negative impact may be small and will almost
certainly be smaller than consumers’ reactions to the presence of other countries such as Mexico, Brazil and
Uruguay on beef labels. If consumer reaction is not negative, Canada will continue to supply weaner and feeder pigs to U.S. feeders depending primarily on the exchange rate between the two countries’ currencies.

Effect of driver and driving style on the stress responses of pigs during a short journey by trailer

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During transportation to an abattoir, pigs can be exposed to a variety of different stressors, eg temperature change, noise and sudden movements (acceleration, braking, cornering) (Lambooij & van Putten 1993). Vibration and unfamiliar movements of the vehicle might elicit a stress response (Dantzer & Mormède 1983; Geers et al 1994). The cardiovascular system is influenced by vibration, resulting in increased heart rate and blood pressure, and peripheral vasoconstriction (Randall et al 1995a). The stress caused by transport may adversely affect animal welfare and cause economic losses related to mortality, carcass damage, and decreased meat quality (Tarrant 1989; Warriss et al 1994). The motion of the floor surface in a transporter is dependent upon the vehicle’s suspension, load, floor rigidity, engine speed, transmission, road speed, road surface, wheel imbalance, etc. Aspects such as acceleration, braking, and cornering, which are under the control of the driver, affect an animal’s ability to maintain postural stability (Randall 1992; Randall et al 1995b). Since 1990 French drivers transporting pigs have undergone education (two-day sessions organised by ITP, Institut Technique de Porc, Paris, France) to help stress that good handling practices are important, not only from an economic point of view, but also in terms of public perception, ie the image consumers have of pig production. After these training sessions started, many slaughterhouses recorded decreased levels of skin damage (Chevillon 1998). The aim of this study was to investigate the possibility of reducing transported pigs’ stress levels by adjusting the driving style of different drivers. To this end, the effect of driver and driving style on pigs’ stress parameters such as behaviour, salivary cortisol concentrations, and heart rate variability was explored during a short journey. Additionally, the effect of different types of trailer acceleration (longitudinal, lateral, and vertical) on these variables was investigated. One hundred and thirty-five cross-bred pigs (Pietrain × Hypor) were transported in groups of five on a trailer towed by a jeep. Three different drivers transported the pigs using a normal, a quiet, and a wild driving style (the latter two in relation to their normal style). Driving style mainly had an effect on the longitudinal and lateral accelerations. Salivary cortisol increases were lowest for the wild driving style. The latter can be explained by the shorter duration of these journeys and not by the accelerations, thus it is our view that acceleration due to manoeuvring as opposed to acceleration due to overall speed should be avoided. Also, in practice, journeys should take as brief a time as possible. Increasing acceleration saw an increase in the proportion of pigs standing during the journey and a decrease in the proportion of pigs lying down. Measurements of variability in heart rate revealed that lateral acceleration was an important stressor for pigs. We concluded that, as driving style has an effect on different stress variables, increased driver awareness of the effects of their driving on the responses of pigs, would improve pig welfare.

For more information the full article can be found at http://www.tandfonline.com/loi/haaw20

Effects of pre-weaning exposure to a maze on stress responses in pigs at weaning and on subsequent performance in spatial and fear-related tests

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Learning, memory and regulation of the stress response are mediated by the hippocampus. Biologically
relevant hippocampal-dependent tasks that develop and integrate cognitive processing of this region may
not be available to piglets in some current production systems. Additionally, weaning piglets at less than two
weeks of age may make them particularly vulnerable to disruptions during cognitive development. We
measured the effects of a spatial maze task (MT) on the stress response of piglets at weaning (12 days of age)
and subsequent fear response (at 7 weeks of age). Twenty-seven pigs from four litters were assigned to one
of three treatments: maze task (MT), isolation control (IC), or control with sow (SC), then combined into
same sex groups with each treatment represented. Each group was tested four times per day from 5–11 days
of age. MT piglets navigated the MT in order to return to the home farrowing crate containing the sow and
litter. IC piglets were isolated for the same length of time taken for the MT piglet in their group to navigate
the MT. SC piglets controlled for handling and were returned to sow as MT entered the MT. Saliva was
collected immediately pre- and post-MT on day 11 to measure cortisol concentrations, which were lower
pre-MT (F(1, 8) = 5.65, P = 0.04). Weaning at 12 days of age increased cortisol concentrations 2 h postweaning
(F(4, 75) = 5.67, P < 0.001). When exposed to a modified Morris water maze (MWM), a
significant interaction of sex and treatment was found with MT males and IC females faster at solving
the MWM than male IC pigs (x2(2) = 9.14, P = 0.01). Lower cortisol concentrations were seen pre-water
maze versus post-water maze (F(1, 19) = 27.62, P < 0.001). At 50 days of age, fear response of pigs was
examined using three fear-related tests (open field test (OFT), novel object test (NOT), and human approach test (HAT), each consisting of 1 m acclimation and 4 m testing. In the HAT, MT animals had a tendency to
touch the unfamiliar person more quickly (F(2, 19) = 2.51, P = 0.10), and more times than animals in other
groups (F(2, 49) = 6.31, P = 0.008). MT may result in less fear of novel persons and ameliorate cognitive
deficits in male pigs, suggesting benefits of exposing young pigs to environments requiring spatial learning.

For more information the full article can be found at http://journals.elsevierhealth.com/periodicals/applan/issues

Effect of controlled alterations in maternal dietary retinol on foetal and neonatal retinol status and pregnancy outcome in pigs

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The objectives of this research were to determine whether alterations in maternal retinol levels during pregnancy programme later foetal and neonatal retinol status and organ development and to determine whether lowered retinol during early or late pregnancy has a greater effect on later development. In addition, the study provided an opportunity to determine whether such dietary modifications affect pregnancy outcomes such as birth weight and within-litter variation in piglet size. The data found indicated that, in the experimental population of animals studied, modest reductions in vitamin A status reduced the incidence of low birth weight piglets and within-litter variability in birth weight pose the intriguing possibility that alterations in dietary retinol could be used to improve pregnancy outcome. This possibility warrants further examination in a larger study.

For more information the full article can be found at http://www.journals.elsevierhealth.com/periodicals/livsci

A regional evaluation of the effect of fiber type in gestation diets on sow reproductive performance

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Data was collected at 3 research stations to determine the effects of added psyllium or soybean hulls to gestation diets on reproductive performance of sows and preweaning performance of their pigs. It was found that sows fed soybean hulls during gestation had reduce BW compared with sows fed the control diets. Also, sows fed psyllium had an increased BW.

Survival analysis of preweaning piglet survival in a dry-cured ham-producing crossbred line

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This study investigated piglet preweaning survival and its relationship with a total merit index (TMI) used for selection of Large White terminal boars for dry-cured ham production. Relationships between sire rankings obtained from different survival models were high. The heritability estimate in equivalent scale was low. The expoitable genetic variation for this trait justifies the inclusion of piglet preweaning survival in the current breeding program.

Differential expression in lung and bronchial lymph node of pigs with high and low responses to infection with porcine reproductive and respiratory syndrome virus

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One hundred Hampshire X Duroc crossbred
pigs and 100 Nebraska Index line pigs were infected
with porcine reproductive and respiratory syndrome virus
(PRRSV) and evaluated for resistance and susceptibility.
Controls (100/line) were uninfected littermates
to infected pigs. Viremia (V), BW change (WTĢ), and
rectal temperature at 0, 4, 7, and 14 d postinfection
were recorded. Lung, bronchial lymph node (BLN), and
blood tissue were collected at necropsy (14 d postinfection).
Infected pigs were classified as low or high responders
to PRRSV based on the first principal component
from principal component analyses of all variables.
Low responders to PRRSV (low PRRSV burden) and
their uninfected littermates were assigned to the low
(L) class. High responders to PRRSV (high PRRSV
burden) and their uninfected littermates were assigned
to the high (H) class. Infected pigs in the L class had
large WTĢ, low V, and few lung lesions; H-class pigs
had small WTĢ, high V, and many lung lesions. Ribonucleic
acid was extracted from lung and BLN tissue of
the 7 highest and 7 lowest responders per line and from
each of their control littermates. A control reference
design was used, and cDNA from each reference sample
tissue was prepared from pooled RNA extracted from
2 control pigs from each line whose infected littermates
had a principal component value of 0. Design variables
in data analyses were line (Index vs. Hampshire X Duroc),
class (H vs. L), treatment (infected vs. uninfected
controls), and slide/pig as error. Oligo differential expression
was based on P < 0.01 occurring in both lung and BLN. Line and treatment effects were significant for 38 and 541 oligos, respectively, in both lung and BLN. Line ~ class interaction existed for expression of thymosin ƒÀ-4, DEAD box RNA helicase 3, acetylcholinesterase, and Homo sapiens X (inactive)-specific transcript in both tissues. Treatment ~ class existed for expression of CCAAT/enhancer-binding ƒÂ protein, nuclear factor of ƒÈ light polypeptide gene enhancer in B cells inhibitor ƒ¿, thioredoxin-interacting protein, major facilitator superfamily domain containing 1, and unknown sequences SS00012040 and SS00012343. Line ~ treatment and line ~ treatment ~ class interactions were not significant. Possible important genetic associations for fine-mapping candidate genes related to response to PRRSV and determining causative alleles were revealed.

Impact of Gestation Housing System on Weaned Pig Production Cost

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Construction and operating costs for two gestation housing systems were compared to assess their impact on cost
per weaned pig produced. The systems compared were: 1) individual gestation stalls in a mechanically ventilated confinement building with slatted floor and 2) group pens with individual feed stalls in deep‐bedded naturally ventilated hoop barns. It was found that in the upper Midwest United States, group housing of gestation sows in deep‐bedded hoop barns may produce pigs at a lower cost than individual gestation stalls in confinement facilities if the bedded group housing system is managed optimally.

Effects of dietary arginine supplementation during gestation and lactation on the performance of lactating primiparous sows and nursing piglets

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This study aimed at determining the effects of dietary arginine supplementation during gestation and lactation on the lactation performance of first-partiy sows. On a weekly basis, BW and backfat (BF) thickness of sows, as well as piglet BW were measured, and blood and milk samples were obtained from the sows. Number of days from weaning to estrus and ADFI were also recorded. It was found that there were no differences in BW, BF thickness, ADFI, or days until return to estrus among treatment groups. Also, there was no effect of the gestation diet or a gestation × lactation diet interaction on any parameter measured. Weight gain of piglets from sows fed the Arg-supplemented diet during lactation was greater between d 0 and 7 and between d 0 and 21 of lactation compared with piglets
from sows fed the control diet. Collectively, results from this study indicate the potential beneficial effects of
dietary Arg supplementation in improving the lactation performance of first-parity sows.