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Effects of choice white grease and soybean oil on growth performance, carcass characteristics, and carcass fat quality of growing-finishing pigs
Posted in: Meat Quality, Production by admin on August 8, 2011 | No Comments
A total of 144 barrows and gilts (initial BW = 44 kg) were used in an 82-d experiment to evaluate the effects of dietary fat source and duration of feeding fat on growth performance, carcass characteristics, and carcass fat quality. Dietary treatments were a cornsoybean meal control diet with no added fat and a 2 × 4 factorial arrangement of treatments with 5% choice white grease (CWG) or soybean oil (SBO) fed from d 0 to 26, 54, 68, or 82. At the conclusion of the study (d 82), pigs were slaughtered, carcass characteristics were measured, and backfat and jowl fat samples were collected. Fatty acid analysis was performed, and iodine value (IV) was calculated for all backfat and jowl fat samples. Pigs fed SBO tended to have increased ADG compared with pigs fed CWG. For pigs fed SBO, increasing feeding duration increased (quadratic) ADG and G:F. For pigs fed CWG, increasing feeding duration improved (quadratic) G:F. For pigs fed SBO or CWG, increasing feeding duration increased carcass yield (quadratic) and HCW (quadratic). Dietary fat source and feeding duration did not affect backfat depth, loin depth, or lean percentage. As expected, barrows had greater ADG and ADFI and poorer G:F than gilts. Barrows also had greater last-rib and 10th-rib backfat and reduced loin depth and lean percentage compared with gilts. Increasing feeding duration of CWG or SBO increased C18:2n-6, PUFA, PUFA:SFA ratio, and IV in jowl fat and backfat. Pigs fed SBO had greater C18:2n-6, PUFA, PUFA:SFA ratio, and IV but decreased C18:1 cis-9, C16:0, SFA, and MUFA concentrations compared with pigs fed CWG in jowl fat and backfat. Barrows had decreased IV in jowl fat and backfat compared with gilts. In summary, adding SBO or CWG increased the amount of unsaturated fat deposited. Increasing feeding duration of dietary fat increases the amount of unsaturated fatty acids, which leads to softer carcass fat.
For more information the full article can be found at http://jas.fass.org/
Effects of feeding diets containing increasing content of corn distillers dried grains with solubles to grower-finisher pigs on growth performance, carcass composition, and pork fat quality
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Crossbred pigs (n = 512) with an average initial BW of 22.1kg were used to evaluate growth performance, carcass characteristics, and pork fat quality of grower-finisher pigs fed corn-soybean meal diets containing increasing content of distillers dried grains with solubles (DDGS). One of 4 dietary treatments was randomly assigned to each pen within sex. Dietary treatment and sex were the main factors in a 3-phase feeding program (BW = 22 to 53 kg, 53 to 85 kg, and 85 to 115 kg). Dietary treatments consisted of a corn-soybean meal control, or a corn-soybean meal diet containing 10, 20, or 30% DDGS. Overall, increasing the dietary DDGS content had no effect on ADG, but ADFI was linearly reduced and G:F was linearly increased. Dressing percentage, LM marbling and firmness, and belly firmness were linearly reduced, but percentage of fat-free lean was linearly increased with increasing dietary DDGS. Subjective LM color score, drip loss, and ultimate pH of LM were not influenced by dietary DDGS. Japanese color scores for backfat and belly fat were similar among dietary treatments. Feeding an increasing content of DDGS linearly increased PUFA concentration, particularly linoleic acid (C18:2), in belly fat, backfat, and LM intramuscular fat, but the increase in LM intramuscular fat was smaller in magnitude than in backfat and belly fat. Pigs fed an increasing content of DDGS had a linear increase in the iodine value of backfat, belly fat, and LM intramuscular fat of 58.4 to 72.4, 61.5 to 72.3, and 54.8 to 57.7, respectively. Oxidation of LM intramuscular fat measured on d 0, 14, 21, and 28 of storage was not affected by dietary treatment. Taste tests for LM showed no effects of diet on flavor, off-flavor, tenderness, juiciness, and overall acceptability scores. Similarly, bacon flavor, off-flavor, crispiness, and overall liking scores were not affected by increasing dietary DDGS, but bacon fattiness and tenderness scores were linearly reduced. These results showed no negative effects on growth performance or dressing percentage when growing-finishing pigs were fed diets containing up to 30% DDGS, but fat quality may not meet the standards of all pork processors when feeding diets containing more than 20% DDGS.
To view this complete article please visit: http://jas.fass.org/
Estimation of genetic trends in French Large White pigs from 1977 to 1998 for growth and carcass traits using frozen semen
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Genetic trends for growth, feed efficiency, composition, and morphometry of carcasses were estimated in a French Large White (LW) pig population using frozen semen. Two groups of pigs were produced by inseminating LW sows with either stored, frozen semen from 17 LW boars born in 1977 or with semen from 23 LW boars born in 1998. In each group, 15 males and 90 females were randomly chosen and mated to produce approximately 1,000 pigs/group. These pigs were performance tested with individual ADFI and serial BW and backfat thickness measurements, slaughtered at 105 kg of BW, and measured for carcass traits. The data were analyzed using mixed linear animal models, including the fixed effect of the experimental group (offspring of 1977 or 1998 boars), the random effect of the additive genetic value of each animal, and, when significant, the fixed effects of sex, fattening batch, and slaughterhouse, the linear regression on BW, and the random effect of the common environment of birth litter. For each trait, the genetic trend was estimated as twice the difference between the 2 experimental groups. Results showed moderately favorable trends for on-test ADG (3.7 g/d per year) and feed conversion ratio (−0.014kg/ kg per year) in spite of a tendency toward an increase in ADFI (7.6g/yr). A strong reduction in carcass fatness (−0.35mm/yr for carcass average backfat thickness) and a large improvement in carcass leanness (0.31mm2/yr and 0.41%/yr for loin eye area and carcass muscle content, respectively) were observed. Carcass shape measurements (back and leg length, back width, muscle thickness of hind limbs) were not affected by selection. Serial measurements of BW and backfat thickness showed that the major part of the genetic gains occurred during late growth and that the reduction in the backfat layer was more pronounced in the rear than in the front part of the carcass. The use of frozen semen appears to be a powerful practice to thoroughly investigate changes attributable to selection.
For more information the full article can be found at http://jas.fass.org/
Feed preferences and performance of nursery pigs fed diets containing various inclusion amounts and qualities of distillers coproducts and flavor
Posted in: Meat Quality, Production by admin on August 5, 2011 | No Comments
We evaluated the preferences of nursery pigs for diets containing increasing distillers dried grains with solubles (DDGS), varying in color, or highprotein distillers dried grains (HP-DDG) and the effects of flavor supplementation on pig preference and growth performance. In Exp. 1 through 5, diet preference was determined in weanling pigs adjusted to a commercial diet for at least 10 d, and then housed individually for a 2-d double-choice preference test. In Exp. 1, a total of 60 pigs (11.6 kg of BW) were given a choice between a reference diet (0% DDGS) and test diets containing 0, 10, 20, or 30% DDGS. In Exp. 2, a total of 80 pigs (10.8 kg of BW) were given a choice between a reference diet (0% HP-DDG) and diets containing 0, 10, 20, or 30% HP-DDG. In Exp. 3, a total of 80 pigs (10.3 kg of BW) were given a choice between a reference diet (0% DDGS) and a diet containing 0%, 30% light, or 30% dark DDGS. In Exp. 4, a total of 80 pigs (11.2 kg of BW) were given a choice between a reference diet without DDGS and a diet containing either 0% DDGS, 10 or 20% light DDGS, or 10 or 20% dark DDGS. In Exp. 5, a total of 108 pigs (9.0 kg of BW) were given a choice between a reference diet (0% DDGS and no flavor) and a diet without or with flavor and containing 0, 10, or 20% DDGS. In Exp. 1 and 2, DDGS and HP-DDG, respectively, linearly decreased pig preference. In Exp. 3, dark DDGS were preferred compared with light DDGS. In Exp. 4, preferences were linearly reduced with DDGS inclusion, and dark DDGS tended to be preferred compared with light DDGS. In Exp. 5, DDGS reduced preference and flavor reduced preference regardless of DDGS level. In Exp. 6, a total of 192 pigs (6.7kg of BW) were fed starter 1 diets without or with flavor for 1 wk. Subsequently, pigs were fed starter 2 and 3 diets (2 wk each) containing 0, 10, or 20% DDGS while continuing to receive their respective flavor treatment. Flavor addition during the starter 1 phase increased ADFI, and DDGS inclusion tended to decrease ADG and decreased ADFI during the starter 2 phase. Volatile components in DDGS and HPDDG varied greatly depending on the source. Nursery pigs preferred a diet without DDGS or HP-DDG, and this appeared to be unrelated to color differences between sources. Knowledge of volatile compounds that enhance or suppress the palatability of feed may lead to further development of feed additives for masking relatively unpalatable, albeit cost-effective, ingredients.
To view this complete article please visit: http://jas.fass.org/
Results from six generations of selection for intramuscular fat in Duroc swine using real-time ultrasound. II. Genetic parameters and trends
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Design of breeding programs requires knowledge of variance components that exist for traits included in specific breeding goals and the genetic relationships that exist among traits of economic importance. A study was conducted to evaluate direct and correlated genetic responses to selection for intramuscular fat (IMF) and to estimate genetic parameters for economically important traits in Duroc swine. Forty gilts were purchased from US breeders and randomly mated for 2 generations to boars available in regional boar studs to develop a base population of 56 litters. Littermate pairs of gilts from this population were randomly assigned to a select line (SL) or control line (CL) and mated to the same boar to establish genetic ties between lines. In the SL, the top 10 boars and 75 gilts were selected based on IMF EBV obtained from a bivariate animal model that included IMF evaluated on the carcass and IMF predicted via ultrasound. One boar from each sire family and 50 to 60 gilts representing all sire families were randomly selected to maintain the CL. Carcass and ultrasound IMF were both moderately heritable (0.31 and 0.38, respectively). Moderate to high genetic relationships were estimated among carcass backfat and meat quality measures of IMF, Instron tenderness, and objective loin muscle color. Based on estimates obtained in this study, more desirable genetic merit for pH is associated with greater genetic value for loin color, tenderness, and sensory characteristics. Intramuscular fat measures obtained on the carcass and predicted using ultrasound technology were highly correlated (rg = 0.86 from a 12-trait analysis; rg = 0.90 from a 5-trait analysis). Estimated genetic relationships among IMF measures and other traits evaluated were generally consistent. Intramuscular fat measures were also genetically associated with Instron tenderness and flavor score in a desirable direction. Direct genetic response in IMF measures observed in the SL corresponded to a significant decrease in EBV for carcass loin muscle area (−0.90 cm2 per generation) and an increase in carcass backfat EBV (0.98 mm per generation). Selection for IMF has led to more desirable EBV for objective tenderness and has had an adverse effect on additive genetic merit for objective loin color.
For more information the full article can be found at http://jas.fass.org/
Evaluation of the prediction of alternative measures of pork carcass composition by three optical probes
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The accuracy of 3 optical probes (HGP4 Hennessey Grading Probe, Destron-Feering PG-100 probe, and Giraldo OPTO-Electronic PG-200 probe) to predict the carcass percentage of 5 alternative measures of carcass composition (fat-tissue-free lean, lipid free soft tissue, lipid-free lean, total fat tissue, and soft tissue lipid) was evaluated on 203 barrows and gilts of 7 genetic populations. The optical probe backfat depths were more closely correlated (0.963 to 0.983) than the LM depths (r = 0.695 to 0.734). The optical probe backfat depths were related to lean percentage (r = −0.82 to −0.88), total fat tissue percentage (r = 0.84 to 0.88), and soft tissue lipid percentage (r = 0.86 to 0.87). Optical probe LM depths were weakly related (r = 0.23 to 0.34) to measures of carcass lean percentage and total fat tissue percentage (r = −0.16 to −0.26). Fat-free lean percentage was predicted with residual SD (RSD) of 3.7% for equations including lastrib midline backfat thickness, 2.4 to 2.7% for equations including optical probe backfat and LM depth, and 2.3% for ribbed carcass measurements. The RSD for the optical probe equations ranged from 2.1 to 2.4% for lipid-free soft tissue percentage and from 2.0 to 2.3% for lipid-free lean percentage. The RSD for the optical probe equations ranged from 2.9 to 3.3% for total fat tissue percentage and 2.5 to 2.8% for soft tissue lipid percentage. Quadratic and cross-product variables of optical probe fat depth, LM depth, and carcass weight were significant and reduced the RSD of the equations. Optical probe backfat and LM measurements can be used to predict alternative measures of carcass composition. The predicted relationships in fat free lean percentage to backfat depth were nearly identical for each optical probe.
For more information the full article can be found at http://jas.fass.org/
Meta-analysis of the effect of the halothane gene on 6 variables of pig meat quality and on carcass leanness
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Technological meat quality is a significant economic factor in pork production, and numerous publications have shown that it is strongly influenced both by genetic status and by rearing and slaughter conditions. The quality of meat is often described by meat pH at different times postmortem, as well as by color and drip loss, whereas carcass quality is often characterized by lean percentage. A meta-analysis of findings relating to 3,530 pigs reported in 23 publications was carried out to assess the effects of the halothane gene, sex, breed, and slaughter weight of animals on 7 selected variables: pH at 45 min postmortem, ultimate pH, reflectance (L*-value), redness (a*-value), yellowness (b*-value), drip loss, and lean percentage. Two statistical methods were used in the meta-analysis: the method of effect size and the better known random effects model. The method of effect size was associated with Markov chain Monte Carlo techniques for implementing Bayesian hierarchical models to avoid the problems of limited data and publication bias. The results of our meta-analysis showed that the halothane genotype had a significant effect on all analyzed pork quality variables. Between-study variance was evaluated with the Cochran (1954) Q-test of heterogeneity. Meta-regression was used to explain this variance, with covariates such as breed, sex, slaughter weight, and fasting duration being integrated into different regression models. The halothane gene effect was associated with the breed effect only for the following variables: L*-value, b*-value, and drip loss. Slaughter weight contributed significantly only to the explanation of differences in ultimate pH between homozygous genotypes. In response to inconsistencies reported in the literature regarding the difference between the genotypes NN and Nn, results of the meta-analysis showed that the difference between these 2 genotypes was significant for all the analyzed variables except the a*-value.
For more information the full article can be found at http://jas.fass.org/
Stepwise chilling: Tender pork without compromising water-holding capacity
Posted in: Economics, Meat Quality by admin on | 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/
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/