Metabolizable energy content of refined glycerin and its effects on growth performance and carcass and pork quality characteristics of finishing pigs

Two studies were conducted with refined glycerin (97.7 and 97.5% glycerin for studies I and II, respectively) to determine ME content and effects on growth performance and carcass and pork quality measures of finishing pigs. An energy balance study using 24 barrows (21.5 ± 0.6 kg initial BW) determined the apparent ME content of glycerin using a generalized randomized block design with 2 dietary treatments: 1) control (99.85% corn + vitamins and minerals) and 2) glycerin (30% of corn in the control diet replaced with glycerin). A 7-d adaptation was followed by a 5-d collection period for feces and urine. The energy content of diets, feces, and urine was determined by bomb calorimetry. The DE of the glycerin diet was greater (P < 0.01) than that of the control diet (4,298 vs. 3,902 kcal/kg of DM); however, the ME content of the 2 diets was similar (3,820 vs. 3,723 kcal/kg of DM). The ME of refined glycerin (estimated by difference) was 3,584 kcal/kg of DM. A growth study was conducted with 128 gilts housed in groups of 4 and reared from 92.5 ± 0.24 kg of BW for a 28-d period, using a split-plot design with a 4 × 2 factorial arrangement of treatments: 1) dietary glycerin level (0, 5, 10, and 15%) and 2) preslaughter handling (gentle vs. intense). The handling treatment was included to simulate the range in handling intensities that are likely to be experienced in practice. At the end of the 28-d period, one-half of the pens on study were slaughtered and used for carcass and pork quality evaluation with 2 pigs from each pen being subjected to each of the preslaughter handling treatments. There were no interactions (P > 0.05) between dietary glycerin and preslaughter handling treatment. Dietary glycerin had no effect (P > 0.05) on growth performance, carcass measures, or meat quality. There were no differences (P > 0.05) between the gentle and intense handling treatments for carcass or pork quality measures. In conclusion, feeding glycerin to finishing pigs at up to 15% of the diet had no negative effect on growth performance or carcass and pork quality characteristics.

The effects of pre-slaughter pig management from the farm to the processing plant on pork quality

Two experiments (Exp.1, n=80; Exp.2, n=144) were conducted to determine the effects of pre-slaughter pig management on pork quality by monitoring blood lactate concentration ([LAC]) during marketing. [LAC] was measured at: (1) baseline at farm, (2) post-loading on truck, (3) pre-unloading after transport, (4) post-unloading at plant, (5) post-lairage, (6) post-movement to stun, and (7) exsanguination. Pearson correlations were used to determine relationships between [LAC] and meat quality. Higher [LAC] post-loading or a greater change in [LAC] during loading resulted in increased 24h pH (P=0.002, P=0.0006, Exp.1; P=0.0001, P=0.01, Exp.2, respectively), decreased L* (P=0.03, P=0.04; P=0.001, P=0.01) and decreased drip loss (P=0.02, P=0.12; P=0.002, P=0.01). Even though improved handling during loading is important to animal well-being, it will not necessarily translate into improved pork quality.

The prevalence of PSE characteristics in pork and cooked ham--effects of season and lairage time

A total of 180 pigs was slaughtered in the same slaughterhouse, but divided in six different trials distributed over Winter (December-March) and Summer (April-September). Meat quality measurements (pH, electrical conductivity, color and/or water-holding capacity) were carried out 30 min, 24 and/or 35h after slaughter in three different muscles: M. gracilis, M. semimembranosus and M. longissimus dorsi. A tendency towards a higher proportion of PSE meat during Summer was found in the examined muscles. Moreover a higher protein, higher dry matter content, a lower water/protein ratio and a lower slicing yield were found for the cooked hams suggesting a higher PSE prevalence in the Summer. A lairage time between 2 and 4h during Summer and less than 2h during Winter was related to a lower proportion of PSE meat. The correlation coefficients between the individual meat quality variables were moderate, but showed the predictive power of the pH measured 24h post-mortem in the M. gracilis for meat quality.

Use of a putative maternal pheromone during transport and the effect of trailer temperatures on pig losses and welfare

The efficacy of a maternal pheromone (MP) to reduce transport stress was evaluated in a field study. In addition, we determined the appropriate field sample sizes for measures of death rate and the proportion of fatigued pigs observed before, during, and after transportation. In the first experiment, semi-truck trailers were randomly treated with 500 mL of MP or isopropyl alcohol as the control (C). Animal handling measures were collected at truck loading, unloading, and from resting pens to the stun area. Blood samples were collected from a sample of transported pigs. In the second experiment, a single truck was used repeatedly for transport to the slaughter plant. The truck and lairage pens were sprayed either with the MP or C, depending on the week (n = 11 weeks). Rate of fatigued pigs coming off the truck was 0.41% for C-treated pigs and 0.15% for MP-treated pigs (P > 0.05). Air temperature recorded in the trailers rose during truck loading and idle time, but levelled off during driving (holding at 1.7°C greater than outside). MP tended to reduce the rate of fatigued pigs (39% although not statistically significant) but it also increased handling difficulty. A power test indicated the sample size needed to detect differences with a statistical significant magnitude (P < 0.05) in future transport studies was 249 trucks (~41 085 pigs).

Effects of supplementing two levels of magnesium aspartate and transportation stress on pork quality and gene expression of micro-calpain and calpastatin of finishing pigs

The objective of this study was to investigate the effects of supplementing swine finishing diets with two levels of magnesium aspartate (MgAsp) and short-term transportation stress on blood parameters, pork quality and the mRNA abundance of p-calpain and calpastatin in muscles of finishing pigs. Thirty-six crossbred finishing pigs (mean BW 90 kg) were assigned randomly to 0, 1000, or 2000 mg supplemental Mg from MgAsp per kg of diet for five days before slaughter. Then six pigs from each dietary treatment were subjected either to no transportation stress (NTS) or 2 h of transportation stress (TS). Transportation stress resulted in higher concentrations (p < 0.01) of serum calcium, glucose and cortisol, lower pH (p < 0.01), higher Warner-Bratzler shear force (WBSF) (p < 0.05) and higher calpastatin mRNA abundance (p = 0.05) of longissimus muscle (LM) compared with NTS treatments. Supplementation of MgAsp in TS treatments increased serum Mg concentration (p < 0.05) at 2000 mg of Mg/kg, reduced drip loss (p < 0.05) and improved pork quality colour (p < 0.05) at 2000 mg of Mg/kg, and decreased 1-day and 3-day WBSF (p < 0.05) at 1000 mg of Mg/kg compared with TS treatments fed the control diet. It is concluded that supplementation of MgAsp improves water-holding capacity and pork colour, and alleviates the negative effects of transportation stress on meat tenderness.

Expression profiling of muscle reveals transcripts differentially expressed in muscle that affect water-holding capacity of pork

To identify biological processes as well as molecular markers for drip loss, a parameter for water holding capacity of meat, the M. longissimus dorsi transcriptomes of six divergent sib pairs were analyzed using Affymetrix Porcine Genome Array. Functional categories of differentially regulated transcripts were determined by single-gene analysis and gene set analysis. The transcripts being up-regulated at high drip loss belong to groups of genes functionally categorized as genes of membrane proteins, signal transduction, cell communication, response to stimulus, and cytoskeleton. Among genes down-regulated with high drip loss, functional groups of oxidoreductase activity, lipid metabolism, and electron transport were identified. Differential regulation of the abundance of transcripts of these biological networks in live muscle affect mortem biochemical processes of meat maturation. Knowledge of this functional link is indicative for the identification of candidate genes for improvement of meat quality.

The relation between glycogen, lactate content and muscle fiber type composition, and their influence on postmortem glycolytic rate and pork quality

This study examined the relation between glycogen, lactate content and muscle fiber type composition, and evaluated their influence on postmortem glycolytic rate and meat quality. Muscle samples were classified based on their glycogen and lactate content at 45min postmortem. Muscles with low glycogen and high lactate levels showed low muscle pH(45min) and high R-values. However, muscles with low glycogen and lactate levels showed normal rates of postmortem glycolysis and normal meat quality. On the other hand, muscles with high glycogen and lactate content showed rapid postmortem glycolysis, paler surface color, higher drip loss, and higher extents of protein denaturation than muscles with high glycogen and low lactate content. These results may be partially explained by muscle fiber type composition. Muscles with low glycogen and lactate content at early postmortem are composed of significantly higher fiber type I and lower fiber type IIB as compared to muscles with high glycogen and lactate content.

Short as well as long transport duration can affect the welfare of slaughter pigs

Attention to the welfare of animals during slaughter transport and lairage at the abattoir is important not only to consumers, but also to the meat production industry. Inadequate transport conditions can result in higher animal mortalities and meat quality problems after slaughter of such animals. In the present study the development of mortality rates both during and after the transport of slaughter pigs, and the incidence of pathological findings, was investigated. It could be shown that the percentage of animals which died during transport and in lairage clearly decreased between 1999 and 2003. This improvement was due mainly to the reduction of animal losses in the summer season where the highest losses over the investigated years occurred. Considering the duration of the transport it could be shown that not only very long (8 h), but also short journeys (1 h) can affect the welfare of animals with increased mortalities and pathological findings during the veterinary inspection at the slaughterhouse, particularly in the summer season. The results presented indicate that the tightening of European animal welfare legislation concerning loading, transport, unloading and lairage of slaughter pigs improved mortality rates and the incidence of pathological findings. Another reason could be a reduction of the percentage of stress susceptible pigs in the porcine population. However, until now the regulations on animal welfare during pig slaughter transport focused only on long-term journeys; the results presented show that short journeys can also affect the welfare of the animals.

Effect of different stunning systems on meat quality of light lamb

The present study was proposed to compare the effect that different types of stunning (TS) had on the quality of refrigerated meat from light lambs of the Spanish Manchega breed at 24h and 7 days post-mortem. Lambs were electrically stunned (ESL; n=10), using CO(2) (GSL; n=10) or slaughtered without previous stunning (USL; n=10). Measurements on meat quality were carried out by evaluating pH, colour coordinates (L(∗), a(∗), b(∗)), water holding capacity (WHC), cooking loss (CL), shear force (SF) and drip loss (DL). At 24h post-mortem, no significant differences were found in any of the variables studied. However, at 7 days post-mortem, meat quality was affected by the different TS: pH, CL and DL were lower (P<0.001) in the USL group and GSL obtained the lowest a(∗) (redness) and b(∗) (yellowness) values (P<0.01) than in the other groups. Ageing of meat affected SF in the ESL group (P<0.01), although there were no significant differences due to treatments at any of the ageing times.

Effects of dietary magnesium and short-duration transportation on stress response, postmortem muscle metabolism, and meat quality of finishing swine1

Crossbred pigs, heterozygous for the halothane gene, were used to determine the effects of long-term dietary supplementation of magnesium mica (MM) and short-duration transportation stress on performance, stress response, postmortem metabolism, and pork quality. Pigs were blocked by weight, penned in groups (six pigs per pen), and pens (three pens per diet) were assigned randomly either to a control corn-soybean meal diet or the control diet supplemented with 2.5% MM (as-fed basis; supplemented at the expense of corn). Diets were fed during the early-finisher (0.95% lysine, as-fed basis; 43.7 to 68 kg) and late-finisher (0.85% lysine, as-fed basis; 68 to 103 kg) periods. At the conclusion of the 71-d feeding trial, 12 pigs from each dietary treatment were selected randomly and subjected either to no stress (NS) or 3 h of transportation stress (TS). Dietary MM had no effect (P > or = 0.40) on ADG or ADFI; however, G:F was improved (P < 0.05) during the early-finisher period when pigs were fed MM-supplemented diets. Plasma glucose concentrations were increased in TS pigs fed the control diet, but transportation did not affect plasma glucose in pigs fed 2.5% MM (diet x transportation stress; P = 0.02). Dietary MM did not affect blood lactate, cortisol, insulin, NEFA, Ca, or Mg concentrations in response to TS (diet x transportation stress; P > or = 0.13); however, circulating lactate, cortisol, and glucose concentrations increased in TS pigs (transportation stress x time; P < 0.01). The LM from TS pigs fed MM had higher initial (0-min) and 45-min pH values than the LM from NS pigs fed the control diet (diet x transportation stress x time; P = 0.07). Lactic acid concentration and glycolytic potential were greater in the LM of TS pigs fed MM than TS pigs fed control diets (diet x transportation stress; P < or = 0.01). Although some trends were identified, neither MM (P > or = 0.15) nor TS (P > or = 0.11) altered the color or water-holding capacity of the LM and semimembranosus. The transportation model elicited the expected changes in endocrine and blood metabolites, but dietary MM did not alter the stress response in pigs. Conversely, although pork quality traits were not improved by dietary MM, delaying postmortem glycolysis and elevating 0- and 45-min muscle pH by feeding finishing diets fortified with MM may benefit the pork industry by decreasing the incidence of PSE pork in pigs subjected to short-duration, routine stressors.