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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.
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Stepwise chilling: Tender pork without compromising water-holding capacity
Posted in: Economics, Meat Quality by admin on August 5, 2011 | No Comments
The current pork slaughter process is primarily optimized to reduce cooler shrink and the incidence of PSE pork. Elimination of the halothane gene and improved preslaughter handling have decreased the incidence of PSE pork and improved the water-holding capacity of the muscle; however, the chilling process has not been optimized to accommodate these changes. The hypothesis that stepwise chilling could improve tenderness without compromising water-holding capacity was tested in this study. The stepwise chilling treatments were composed of a rapid chilling to 10 or 15°C (in a chilling tunnel) and a 6-h holding period at 10 or 15°C, followed by rapid chilling to 4°C. Both treatments were compared directly with a chilling treatment that simulated conventional tunnel chilling; one carcass half from each pig was allocated to a stepwise chilling treatment, whereas the other carcass half was allocated to the control treatment. A total of 42 pigs were slaughtered on 6 slaughter days. Biopsies were collected for analysis of glycogen degradation and glycogen debranching enzyme activity from slaughter until 72 h postmortem, and samples for color, sarcomere length, drip loss, Warner- Bratzler shear force, and sensory analysis were removed from the carcass 24 h postmortem. Substantial temperature differences were obtained during the holding period between the stepwise and conventionally chilled carcass halves. These had almost, but not completely, disappeared by 22 h postmortem, and although the differences were small, pH was significantly less in the stepwise-chilled carcasses compared with the control carcasses. The stepwise chilling treatments led to significantly improved tenderness in LM without compromising quality indicators or attributes such as pH, drip loss, or ham processing yield, although color of the stepwise-chilled pork was affected. Neither the tenderness of processed semimembranosus muscle nor the shear force of biceps femoris muscle was affected because of the smaller temperature differences in these muscles. The improvements in tenderness could be solely attributed to the increased proteolysis postmortem in the stepwise-chilled carcasses, with the greater temperatures favoring proteolytic enzymes involved in muscle protein degradation. Furthermore, the results for glycogen metabolism successfully revealed that both pro- and macroglycogen contributed to the energy generation in postmortem muscles, with degradation of both forms early postmortem.
For more information the full article can be found at http://jas.fass.org/
Correlative responses for carcass and meat quality traits to selection for ovulation rate or prenatal survival in French Large White pigs
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Correlated effects of selection for components of litter size on carcass and meat quality traits were estimated using data from 3 lines of pigs derived from the same Large White base population. Two lines were selected for 6 generations on high ovulation rate at puberty (OR) or high prenatal survival corrected for ovulation rate in the first 2 parities (PS). The third line was an unselected control (CON). The 3 lines were kept for a 7th generation, but without any selection. Carcass and meat quality traits were recorded on the 5th to 7th generation of the experiment. Carcass traits included dressing percentage, carcass length (LGTH), average backfat thickness (ABT), estimated lean meat content, and 8 carcass joint weight traits. Meat quality traits included pH recorded 24 h after slaughter (pH24) of LM, gluteus superficialis (GS), biceps femoris (BF), and adductor femoris (AD) muscles, as well as reflectance and water-holding capacity (WHC) of GS and BF muscles. Heritabilities of carcass and meat quality traits and their genetic correlations with OR and PS were estimated using REML methodology applied to a multiple trait animal model. Correlated responses to selection were then estimated by computing differences between OR or PS and CON lines at generations 5 to 7 using least squares and mixed model methodology. Heritability (h2) estimates were 0.08, 0.58, 0.70, and 0.74 for dressing percentage, LGTH, ABT, and lean meat content, respectively, ranged from 0.28 to 0.72 for carcass joint traits, from 0.28 to 0.45 for pH24 and reflectance measurements, and from 0.03 to 0.11 for WHC measurements. Both OR and PS had weak genetic correlations with carcass (rG = −0.09 to 0.17) and most meat quality traits. Selection for OR did not affect any carcass composition or meat quality trait. Correlated responses to selection for PS were also limited, with the exception of a decrease in pH24 of GS and BF muscles (−0.12 to −0.14 after 6 generations), in WHC of GS muscle (−18.9 s after 6 generations) and a tendency toward an increase in loin weight (0.44 kg after 6 generations).
For more information the full article can be found at http://jas.fass.org/
Genetic parameters of piglet survival and birth weight from a two generation crossbreeding experiment under outdoor conditions designed to disentangle direct and maternal effects
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Multivariate Bayesian linear-threshold models were used to estimate genetic parameters of peri- and postnatal piglet survival and individual birth weight of piglets reared under outdoor conditions. Data of 21,835 individual piglet observations were available from a 2-generation crossbreeding experiment selected for direct and maternal genetic effects of postnatal piglet survival on piglet and dam levels, respectively. In the first generation, approximately one-half of the Landrace sires used were selected for large or average breeding values of maternal genetic effects on postnatal piglet survival, whereas in the second generation the Large White sires used were selected for direct genetic effects of the same trait. Estimates of direct and maternal heritability were 0.21 and 0.15, 0.24 and 0.14, and 0.36 and 0.28 for piglet survival at birth and during the nursing period, and individual birth weight, respectively. In particular, direct heritabilities are substantially large than those from the literature estimated for indoor reared piglets, suggesting that genetic effects of these traits are substantially greater under outdoor conditions. Direct or maternal genetic correlations between survival traits or with birth weight were small (ranging from 0.06 to 0.17), indicating that peri- and postnatal survival are genetically under rather different control, and survival was only slightly positively influenced by birth weight. There were significant negative genetic correlations between direct and maternal genetic effects within each of the analyzed traits ranging from –0.36 to –0.45, which have to be considered when selecting for piglet survival. Adjustment of traits for litter size or inclusion of genetic groups showed insignificant effects on the magnitude of the estimated genetic parameters. The magnitude of genetic parameters suggested that there is substantial potential for genetic improvement of survival traits and birth weight in direct and maternal genetic effects, especially when piglets are kept under outdoor conditions.
For more information the full article can be found at http://jas.fass.org/
Effect of temperature on thermal acclimation in growing pigs estimated using a nonlinear function
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Ninety-six Large White growing barrows were used to determine the effect of temperature on thermoregulatory responses during acclimation to increased ambient temperature. Pigs were exposed to 24°C for 10 d and thereafter to a constant temperature of 24, 28, 32, or 36°C for 20 d. The study was conducted in a climate-controlled room at the INRA experimental facilities in Guadeloupe, French West Indies. Relative humidity was kept constant at 80% throughout the experimental period. Rectal temperature, cutaneous temperature, and respiratory rate were measured [breaths per minute (bpm)] 3 times daily (0700, 1200, and 1800 h) every 2 or 3 d during the experiment. The thermal circulation index (TCI) was determined from rectal, cutaneous, and ambient temperature measurements. Changes in rectal temperature, respiratory rate, TCI, and ADFI over the duration of exposure to hot temperatures were modeled using nonlinear responses curves. Within 1 h of exposure to increased temperature, rectal temperature and respiratory rate increased by 0.46°C/d and +29.3 bpm/d, respectively, and ADFI and TCI decreased linearly by 44.7 g∙d−2∙kg−0.60 and 1.32°C/d, respectively until a first breakpoint time (td1). This point marked the end of the short-term heat acclimation phase and the beginning of the long-term heat acclimation period. The td1 value for ADFI was greater at 28°C than at 32 and 36°C (2.33 vs. 0.31 and 0.26 d, respectively), whereas td1 for the TCI increase was greater at 36°C than at 28 and 32°C (1.02 vs. 0.78 and 0.67 d, respectively). For rectal temperature and respiratory rate responses, td1 was not influenced by temperature and averaged 1.1 and 0.89 d, respectively. For respiratory rate and rectal temperature, the long-term heat acclimation period was divided in 2 phases, with a rapid decline for both variables followed by a slight decrease. These 2 phases were separated by a second threshold day (td2). For rectal temperature, td2 increased significantly with temperature (1.60 vs. 5.16 d from 28 to 36°C). After td2, the decline in rectal temperature during the exposure to thermal challenge was not influenced by temperature, suggesting that the magnitude of heat stress would affect thermoregulatory responses only at the beginning of the long-term heat acclimation period. The inclusion of random effects in the nonlinear model showed that whatever the temperature considered, interindividual variability of thermoregulatory responses would exist.
For more information the full article can be found at http://jas.fass.org/
Association analyses of candidate single nucleotide polymorphisms on reproductive traits in swine
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The ability to identify young females with superior reproduction would have a large economic impact on commercial swine production. Previous studies have discovered SNP associated with economically important traits such as litter size, growth rate, and feed intake. The objective of this study was to test for association of candidate SNP with sow prolificacy reproductive traits in gilts of a Landrace-Duroc- Yorkshire composite population. Association analyses regressed additive (A), dominant (D), and imprinting (I) SNP effects on each trait with an animal model. A carnitine palmitoyltransferase 1A SNP and a glycogen synthase 1 SNP were associated with age at puberty (AP; D = 10 d and A = 3.8 d, respectively). Four IGF2 SNP were associated with AP as well, having additive or dominant effects (3.2 to 5.8 d). Two mannosidase 2B2 SNP and 2 prolactin receptor (PRLR) SNP were also associated with AP. Solute carrier 22, subfamily member 5 SNP was weakly associated with AP (D = 3.9 d). Polymorphisms within glycogen synthase 1 and protein kinase AMP-activated, gamma 3 noncatalytic subunit had associations with ovulation rate. Estrogen receptor (ESR) 1, ESR2, PPAR γ coactivator 1, and IGFBP3 SNP were significantly associated with weaning-to-estrus interval. Two PRLR SNP were associated with total number of piglets born (A = 0.57 piglets; and D = 0.61 piglets, respectively). A SNP within PRLR was also associated with number of piglets born alive (D = 0.61). The PPAR γ coactivator 1 SNP was associated with total number of piglets born (D = 0.38 piglets) and number of piglets born alive (D = 0.53 piglets). The SNP within ESR1 (A = 0.65 piglets), ESR2 (A = −0.33 piglets), IGF2 SNP (A = −0.26 piglets), and IGFBP3 SNP (D = 0.35 piglets) were associated with number of piglets born dead. A leptin SNP was associated with mummified fetuses (D = 0.09 piglets). Many of the SNP analyzed in this study are from genes involved in regulation of metabolism, suggesting that there is an important link between physiological events associated with reproduction and energy utilization. Furthermore, these production and growth trait SNP may serve to assist in selection of young females for superior reproductive performance.
For more information the full article can be found at http://jas.fass.org/
Behavior and peripheral amine concentrations in relation to ractopamine feeding, sex, and social rank of finishing pigs
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Aggression can impair productivity and well-being. The association between aggression in finishing pigs and the feed additive ractopamine (RAC), a β-adrenoreceptor agonist, is unknown and warrants further investigation. Our goal was to examine behavioral activity, including aggression, in the home pen and concentrations of peripheral amines in barrows and gilts, taking into account diet (RAC) and social rank. Sixty-four finishing pigs, housed in pens of 4 by sex, were fed either a control (CTL) or RAC-added (5 mg/ kg for 2 wk plus 10 mg/kg for another 2 wk) diet. The top dominant and bottom subordinate pigs in each pen were determined at mixing (2 wk pretrial). The behavior of all pigs was recorded continuously during the pretrial week (baseline) and for the following 4 wk. These behavioral data were used to evaluate home pen aggression, including the number of agonistic interactions (AINX) and constituent aggressive actions, during a 3-h period (0800 to 1100 h) once per week and their change in relation to the baseline. Time-budget behaviors and postures were analyzed over eight 24-h periods (2 d/wk) using 10-min instantaneous scan sampling that focused on only the dominant and subordinate pigs in each pen. These 2 pigs were also subjected to blood collection once per week during the trial to determine concentrations of dopamine, norepinephrine, epinephrine, and serotonin (5-HT) using HPLC. Gilts performed more bites and total actions per AINX than barrows, and RAC-fed gilts increased bites and pursuits, whereas these behaviors decreased compared with baseline values in all other subgroups. Gilts fed RAC increased the total number actions per AINX, whereas the occurrence of AINX decreased for all subgroups. Overall, RAC-fed pigs were more behaviorally active, spending more time alert, bar biting, and sham chewing compared with CTL pigs. The dominant RAC-fed pigs tended to have the greatest norepinephrine concentrations among the tested subgroups. Dominant barrows had greater epinephrine concentrations than subordinate barrows. The RAC-fed gilts tended to have lesser 5-HT concentrations than CTL gilts, whereas concentrations were similar in barrows. Greater activity and the increase in oral-related behaviors observed in RAC-fed pigs may be mediated by the increase in arousal caused by RAC. Intensified aggression in gilts, especially when fed RAC, may be linked to reduced central 5-HT and greater noradrenergic activity, and further research on brain neurotransmitters in gilts is needed.
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Aggressiveness and brain amine concentration in dominant and subordinate finishing pigs fed the β-adrenoreceptor agonist ractopamine
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Under farm conditions, aggression related to the formation of social hierarchy and competition for resources can be a major problem because of associated injuries, social stress, and carcass losses. Any factor that may affect the regulation and amount of aggression within a farmed system, for instance, feeding the β-adrenoreceptor agonist ractopamine (RAC), is therefore worthy of investigation. The objectives of this study were to assess the effects of the widely used swine feed additive RAC, considering also the effects of sex and social rank on aggressiveness and concentrations of brain amines, neurotransmitters essential for controlling aggression, in finishing pigs. Thirty-two barrows and 32 gilts (4 pigs/pen by sex) were fed either a control diet or a diet with RAC (Paylean, Elanco Animal Health, Greenfield, IN) added (5 mg/kg for 2 wk, followed by 10 mg/kg for 2 wk). The top dominant and bottom subordinate pigs (16 pigs/sex) in each pen were determined after mixing by a 36-h period of continuous behavioral observation. These pigs were then subjected to resident-intruder tests (maximum 300 s) during the feeding trial to measure aggressiveness. At the end of wk 4, the amygdala, frontal cortex, hypothalamus, and raphe nuclei were dissected and analyzed for concentrations of dopamine (DA); serotonin (5-HT); their metabolites 3,4-dihydroxyphenyl acetic acid (DOPAC) and homovanillic acid, and 5-hydroxyindoleacetic acid (5-HIAA), respectively; norepinephrine; and epinephrine using HPLC. Ractopamine-fed gilts performed more attacks during the first 30 s of testing than pigs in all other subgroups. By the end of the resident-intruder test (300 s), the dominant control gilts and barrows, and both dominant and subordinate RAC-fed gilts performed the greatest percentage of attacks. Gilts had decreased norepinephrine and DOPAC concentrations in the amygdala and frontal cortex, and when fed RAC, gilts also had the least 5-HIAA concentration and greatest DA turnover rate in the amygdala. The 5-HT concentration was less in the frontal cortex of gilts compared with barrows and in the raphe nuclei (single site for brain 5-HT synthesis) of dominant gilts. Ractopamine may be affecting aggressive behavior through indirect action on central regulatory mechanisms such as the DA system. The aggressive pattern observed in the tested pigs, especially in gilts, is likely linked to brain monoamine profiling of a deficient serotonergic system in the raphe nuclei, amygdala, and frontal cortex, and enhanced DA metabolism in the amygdala, brain areas vital for aggression regulation.
For more information the full article can be found at http://jas.fass.org/
Effect of dietary organic and inorganic micromineral source and level on sow body, liver, colostrum, mature milk, and progeny mineral compositions over six parities
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A sow study evaluated the effects of 2 dietary micromineral sources (organic or inorganic) and 3 dietary mineral levels [NRC, industry (IND), and IND + Ca:P] with selected sows killed at parities 1, 2, 4, and 6. Three sows per treatment group were killed at weaning (total = 68), and their body and liver, 72 colostrum and milk samples (17 d), 69 full-term stillborn pigs and their livers, and 32 pigs at weaning were analyzed for minerals. Tissue and milk samples from the sows were analyzed as a 2 × 3 × 4 factorial arrangement of treatments in a completely randomized design (CRD) with 3 replicates per treatment. Full-term stillborn pig mineral compositions were determined at parities 1, 3, and 5 and evaluated as a 2 × 3 × 3 factorial arrangement of treatments in a CRD with 3 replicates per treatment. Weanling pigs from parity 6 sows were analyzed as a 2 × 3 factorial in a CRD. Sow and pig mineral compositions are reported on an equivalent empty BW and kilograms of liver weight basis. The results indicated that sow body macromineral contents were not affected by dietary micromineral source or level or when the diets contained added Ca and P. Sow body Se increased when dietary organic microminerals increased from the NRC to the IND level, resulting in a source × level interaction, but there was no increase in those sows fed inorganic microminerals. There were increases in Cu and Se as levels increased from NRC to the IND, and there were increases in Cu and Zn when the IND + Ca:P diet was fed compared with feeding the IND diet. Increases in sow liver Cu, Se, and Zn occurred as microminerals increased from the NRC to the IND level. As parity advanced, there were cubic increases in sow body Cu, Fe, and Se, but a quadratic increase in Zn. There was no clear effect of sow dietary treatments on full-term stillborn pig or liver micromineral contents, except Se. There was a greater pig body Se content when sows were fed organic microminerals at the greater level, resulting in a source × level interaction. Colostrum minerals were generally not affected by diet variables, except Se. Colostrum Se was greater when sows were fed the organic micromineral source than the inorganic source at the greater level, resulting in a source × level interaction. Milk Cu and Zn increased as dietary level increased. Milk Se was increased when organic Se was fed and when the micromineral level was increased. Weaned pig body Fe and Se were greater when organic microminerals were fed to the sow, whereas Mn and Zn increased when the IND level was fed. These results indicate that the dietary micromineral source and level had a minimal effect on sow body and liver mineral contents or in colostrum and pigs at birth, except Se, which was greater when the organic form was fed.
For more information the full article can be found at http://jas.fass.org/
Transfer of conjugated linoleic acid from sows to their offspring and its impact on the fatty acid profiles of plasma, muscle, and subcutaneous fat in piglets
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This experiment was conducted to determine if CLA could be transferred from sows to their offspring through the umbilical cord or milk. Eighteen pregnant Dalland sows of mixed parity were used in a completely randomized block design based on parity and BW. The sows were allotted to 1 of 3 groups and fed diets containing 0, 0.5, or 1.0% CLA during the last 50 d of gestation and throughout a 26-d lactation (n = 6). Umbilical cord blood was sampled at parturition. Colostrum and milk were collected from each sow on d 2 and 15 after farrowing. Samples of blood, backfat, and the LM were obtained from piglets at 2 and 26 d of age. Sow reproductive performance and piglet growth were not altered by CLA supplementation during the late gestation and lactation periods. The CLA supplementation of sow diets had an impact on the fatty acid profiles in colostrum and milk. Dietary CLA increased the concentrations of total SFA (linear and quadratic), but reduced the total MUFA in the colostrum (linear and quadratic). Although dietary CLA increased the concentrations of total SFA (quadratic), it had no influence on total MUFA concentrations in the milk. In addition, feeding sows diets supplemented with CLA resulted in increases (linear and quadratic) in the CLA content of plasma, backfat, and the LM in their offspring. However, trans-10, cis-12–18:2, rather than cis-9, trans-11–18:2, was detected in the umbilical cord blood, which indicates that CLA may be transported from the sow to the fetus in an isomer-specific manner.
For more information the full article can be found at http://jas.fass.org/
Technical note: Efficient protocol for isolation of total ribonucleic acid from lyophilized fat and muscle pig samples
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Isolation of total RNA from frozen muscle and fat samples typically results in small yields due to the presence of connective tissue between muscle fibers, which impairs complete tissue homogenization, and the excess of fat and relatively small cellularity of adipose tissue. Meat quality studies involve determination of fatty acid composition and content from muscle and subcutaneous fat samples, a process that may produce an excess of lyophilized tissue samples. The purpose of this work was to investigate the stability of total RNA in lyophilized tissue samples generated during the routine detection of fatty acid content of pig muscle and fat tissues, stored at room temperature or at −20°C. The protocol described here results in increased yields of total RNA from freeze-dried samples stored at −20°C, which facilitates the homogenization step. The isolated RNA is suitable for common gene expression techniques such as final point and quantitative reverse transcription-PCR.
For more information the full article can be found at http://jas.fass.org/