Technological Meat Quality Research Articles

Compensatory growth response in pigs: Effects on growth performance, composition of weight gain at carcass and muscle levels, and meat quality1

A restriction/realimentation feeding strategy was applied to pigs to increase the age at market weight and final ADG, modify protein and lipid deposition rates at carcass and muscle levels, and thereby improve eating quality of the pork. A total of 126 Duroc x (Large White x Landrace) pigs (females and castrated males) were used. At the average BW of 30 kg, within litter and sex, pairs of littermates (blocked by BW) were randomly assigned to ad libitum (AL) feeding during growing (30 to 70 kg of BW) and finishing (70 to 110 kg of BW) periods (AL, n = 56), or restricted feeding at 65% of the ADFI of the AL pigs, on a BW basis, during the growing period and AL feeding during finishing (compensatory growth, CG; n = 56). In each feeding regimen, 15 pigs were slaughtered at 70 kg of BW, and 41 pigs were slaughtered at 110 kg of BW. Additionally, 14 pigs were slaughtered at 30 kg of BW to calculate tissue deposition rates. The CG pigs showed decreased ADG (-35%, P = 0.001) during growing but increased ADG (+13%, P = 0.001) during finishing (i.e., compensatory growth) due to greater (P = 0.001) ADFI and G:F. Hence, CG pigs were 19 d older at 110 kg of BW than AL pigs. The CG pigs were leaner at 70 kg of BW than AL (e.g., 11.7 vs. 13.5 mm of average backfat thickness for CG and AL pigs, respectively, P = 0.023), whereas the differences were reduced at 110 kg of BW (20.6 vs. 21.0 mm of average backfat thickness for CG and AL pigs, respectively, P = 0.536). At 70 kg of BW, intramuscular fat (IMF) content of LM did not differ between CG and AL pigs (1.25 vs. 1.49%, respectively, P = 0.118), whereas CG pigs had less IMF in LM at 110 kg of BW (2.19 vs. 2.53% for CG and AL pigs, respectively, P = 0.034). Feeding regimen influenced the composition of weight gain. From 30 to 70 kg of BW, feed restriction reduced (P = 0.001) lean and adipose tissue deposition at the carcass level and protein and lipid deposition at the muscle level. From 70 to 110 kg of BW, the CG feeding strategy increased (P = 0.016) deposition of adipose but not of lean tissue at the carcass level. However, lipid and protein deposition at the muscle level were not affected. Thus, realimentation promoted deposition of subcutaneous fat over IMF. Feeding regimen hardly affected technological meat quality at 110 kg of BW. The CG feeding strategy decreased (P = 0.014) the meat juiciness score in relation to the decreased IMF but did not influence other sensory traits. Elevated IMF content and improved pork quality might be achieved by modifying the onset or duration of the restriction and realimentation periods.

Effect of partial substitution of standard meal in chicken feed by rape seed on carcass and meat quality

Effect of partial substitution of crushed soybean by different portions of rape seed on yield and chicken breast quality (nutritive and technological) was investigated in the paper. ROSS 308 hybrids were used for investigations. Control group (K) was fed with standard mixture and experimental groups with mixture in which crushed soybean partially substituted by 10% (O1), 15% (O2) and 20% (O3) extruded rape seed (EZUR). Rape seed was extruded with corn germ in ratio 50:50. It was concluded that there are no significant differences in breast meat yield between control and experimental groups (P > 0.05). The changes in chicken meal had no influence (P > 0.05) on nutritive quality of breast meat (the contents on protein, connective tissue protein, free fat and total ash). Additionally was found that the technological quality of breast meat of the control and experimental groups averagely corresponds to "normal" meat quality considering the parameters and criteria for quality determination (pHu, L*, water holding capacity).

Performance, carcass and technological meat quality of pigs in indoor and outdoor production systems

This study aimed to compare different production systems, i.e., the combined effect of outdoor and indoor rearing of pigs and organic diets fed ad libitum or restrictively. Furthermore, the suitability of two breed crosses for outdoor rearing was studied. The effects on performance, carcass and technological quality traits were investigated. During two years, 240 pigs of Duroc x Large White (D*LW) and Swedish Landrace x Large White (L*LW) were allocated to three production systems: 1) Pigs kept outdoors, fed an organic diluted diet (20% alfalfa roughage) ad libitum; 2) Pigs kept outdoors, strategically fed a diluted organic diet up to a live weight of approximately 80 kg and thereafter an undiluted organic diet ad libitum; 3) Pigs kept indoors, fed an undiluted organic diet restrictively. For outdoor pigs, strategic feeding increased daily weight gain and backfat thickness, compared with feeding a diluted diet throughout (p≤0.01). L*LW pigs in both outdoor systems grew slower than in the indoor system (p≤0.001), whereas for D*LW pigs only outdoor pigs fed the diluted diet had a slower growth rate. Outdoor pigs had lower dressing percentage than indoor pigs. Glycogen content and L* values in M. longissimus dorsi were higher, whereas b* values were lower in meat from pigs in the indoor system. D*LW pigs had higher water-holding capacity (lower drip, thawing and cooking losses), lower shear force and higher intramuscular fat content compared with L*LW pigs.

Effect of single-sex or mixed rearing and live weight on performance, technological meat quality and sexual maturity in entire male and female pigs fed raw potato starch

The aim of our study was to investigate the effect of rearing system (mixed or single-sex) on performance and carcass quality of entire male and female pigs slaughtered at around 90 or 115 kg live weight. We also studied the combined effect of live weight and dietary supplement of raw potato starch (RPS) on technological meat quality for both sexes, and boar taint compounds in entire male pigs. Furthermore, we investigated pre-slaughter routines (pen-wise or mixing with unfamiliar pigs) and sexual maturity. A total of 408 growing/finishing pigs were included in this two-year study. Performance did not differ significantly between entire male and female pigs irrespective of rearing system, except for daily weight gain in the interval from 90 kg to slaughter. Mixed pigs had significantly higher daily weight gain in this interval than single-sex pigs. Entire male pigs had higher carcass lean meat content than female pigs (1.6 percentage units). Technological meat quality differed only slightly between the sexes. Females reared in mixed pens were sexually more mature than female pigs reared in single-sex pens, and mature females had higher growth rate but lower meat content in carcasses than immature females. In contrast, female contact did not influence sexual maturity of entire male pigs. Mixing entire male pigs with unfamiliar pigs at the abattoir resulted in more damaged skin compared with pen-wise keeping whereas female pigs had almost no visible skin damage. We therefore recommend that entire male pigs are not mixed with unfamiliar pigs during transport and at the abattoir, because of fighting and subsequent skin damage. The levels of skatole in fat were significantly lower in high-weight entire male pigs fed RPS compared to high-weight pigs without RPS. Androstenone levels in fat were high in all groups.

The effects of breed cross on performance and meat quality of once-bred gilts in a seasonal outdoor rearing system

Abstract. This study investigated the suitability of once-bred gilts of two different breed crosses in an alternative seasonal outdoor rearing system, with slaughter of the once-bred gilts and their progeny at the end of the season. In total 38 once-bred gilts (Large White x Landrace (LW*L) and Large White x Duroc (LW*D) were housed outdoors one month before farrowing until slaughter, 2-3 weeks after weaning. Body weight, backfat thickness and litter size of the once-bred gilts, and pre-weaning mortality and growth of the piglets were recorded. Carcass quality and technological meat quality (pHu, internal and surface reflectance, water-holding capacity, processing yield and shear-force) of m. longissimus dorsi were measured. Sensory meat quality (taste panel) of oven-baked loin (m. longissimus dorsi) and cured and smoked ham (m. semimembranosus) was investigated. LW*L once-bred gilts had more piglets at weaning, whereas growth rate of LW*D progeny was higher; pre-weaning mortality and litter weight did not differ between the breeds. LW*L had higher lean meat content and lower backfat thickness. Technological meat quality and chemical composition did not considerably differ between the two breed crosses. LW*D had higher quality with regard to meat flavour and stringiness, but tended to have lower quality with regard to juiciness of cured and smoked ham, compared with LW*L.

The Influence of Production Systems on Meat Quality, with Emphasis on Pork

Technological, nutritional, and sensory meat quality may be influenced by multiple interacting factors before and after slaughter. Reviewing the literature, it can be seen that alterations aimed at creating more sustainable production systems for pig meat generally have either no effect or a lowering effect on the ultimate pH value of the meat. Some studies indicate reduced water-holding capacity in sustainably produced pork. Outdoor production may be expected to increase further the shear force of the meat compared to conventional systems. The color may be affected in different ways, leading to either darker, more pigmented meat or paler, structurally effected meat. The more unsaturated profile of the lipids in meat produced in a system that includes feeds containing polyunsaturated fatty acids is favorable with respect to the nutritional quality of the meat. To conclude, the combinatory effects of, for example, feeding, production systems, genotype, sex, and preslaughter treatments, have to be addressed.

Genetic variability within and between breeds of poultry technological meat quality

The increasing importance of the technological quality of meat, defined as its ability to be stored or further-processed, has highlighted the need for research work on the genetic control of meat characteristics, which has been seldom studied in poultry until now. Both the variabilities of quality indicators between genetic types and within populations in selection are being studied. These complementary approaches aim at defining the possibilities of a genetic improvement of meat quality and the relationships with growth performances of the birds. This implies a better knowledge of the mechanisms involved in meat quality, in order to identify the most relevant criteria of selection. Results obtained up to now in chickens lead to the consensual conclusion that the increased breast mass obtained by genetic selection has mainly been achieved by an increased fibre size, while no changes in the metabolic profile were detected. According to the genetic parameters obtained up to now, the technological quality of the meat could be efficiently improved by the genetic route. Indeed, heritabilities of quality characteristics obtained in the chicken under experimental conditions are high. At the same time, the estimated correlations do not show any genetic antagonism between the birds' performances and the quality of their meat. All these results thus favour selection on the quality of the meat, even if its implementation remains in the hands of the breeders, according to the return in terms of competitiveness. According to the available results, the ultimate pH could be a relevant criterion of selection because of its strong relationship to the colour, the water-holding capacity or the texture of the meat. Much research however remains to be undertaken to optimise the efficiency of selection on the quality of the meat. In particular, interactions with pre-slaughter stresses must be specified, as they can strongly affect meat quality. On the other hand, it is hoped that significant progress in the methods of selection based on the quality of the meat will be brought by the identification of molecular markers of meat quality.

Carcass quality and technological and sensory meat quality of once-bred gilts in a seasonal outdoor rearing system

Seasonal application of once-bred gilts for piglet and meat production outdoors could be a worthwhile alternative rearing form to normal commercial production. Compared with growing/finishing pigs, payment for sow carcasses is considerably reduced because of an assumed decrease in meat quality and processing properties. The purpose of this study was to compare maiden and once-bred gilts for carcass quality, and technological and sensory meat quality. The control group of 14 gilts (LW*L and LW*D) was reared indoors and slaughtered unmated at an average live weight of 145 kg. In contrast, 38 once-bred gilts of the same breeds were initially reared like the maiden control, inseminated and then housed outdoors from one month before farrowing until slaughter. Carcass traits, technological meat quality (pH, internal and surface reflectance, water holding capacity, commercial processing yield (total yield) and laboratory processing yield (Napole yield), WB shear force and chemical composition of M. longissimus dorsi were measured. Sensory meat quality (taste panel) of oven-baked M. longissimus dorsi and cured and smoked M. semimembranosus et adductor was investigated. Carcass quality traits such as higher lean meat content and lower backfat thickness were preferable with the once-bred gilts. For technological meat quality characteristics, once-bred gilts had lower thawing loss, Napole yield, dry matter and higher total work of WB shear force and intramuscular fat, compared to maiden gilts. In general, sensory meat quality was comparable between the two groups. In processed meat only, once-bred gilts had higher juiciness and salinity and unfavourable increased stringiness, compared to maiden gilts. Thus, once-bred gilts produce valuable carcasses and are suitable for an outdoor seasonal rearing system.

Effect of extra maternal feed supply in early gestation on sow and piglet performance and production and meat quality of growing/finishing pigs

The influence of differentiated extra maternal feed allowance during early gestation on maternal performance and postnatal development of the progeny from gilts and sows was investigated. Four different feed allowances of the same diet (Control [C], +35% [T35], +70% [T70], +100% [T100]) were assigned to 20 crossbred gilts (Swedish Landrace×Swedish Yorkshire), which continued as sows with the same feed allowance the following parity. The progeny was uniformly raised and slaughtered at a live weight of 110 kg. Additional maternal feed allowance resulted in significantly more weaned piglets per sow but not per gilt. Piglet numbers did not increase from T35 to T70/T100. Piglet birth weight did not increase due to maternal feeding. The intra-litter variation in piglet birth weights was similar between the treatments. Independent of the additional feed allowance, all gilts and sows had similar weights after weaning and had good body condition. The growth rate of progeny from sows was negatively related to maternal feed supply; for progeny from gilts, no clear trend of nutritional influence could be observed. Carcass and technological meat quality was not affected by maternal feeding treatment. Birth weight positively affected later growth performance (daily weight gain), carcass quality (lean meat content, back fat, proportion of muscles in ham/loin), whereas technological meat quality was unaffected.

Quality Characteristics of Fresh Meat from Pigs of the Gascon Breed

Chemical parameters involved in technological meat quality for dry cured processing of Gascon pigs were studied in longissimus dorsi (LD) and biceps femoris (BF) muscles. Muscles from Gascon pigs showed 2.60 and 2.84% of intramuscular fat content, 23.64 and 22.14% protein content and 1.34 and 4.63mg of myoglobin per gram of muscle (respectively LD and BF). Intramuscular fat (IMF) and myoglobin levels were higher than those reported for commercial pigs, but lower than those previously found in Iberian pigs. A similar situation was detected in the fatty acid composition of neutral and polar lipids of both muscles. Thus, monounsaturated fatty acids (MUFA) in neutral lipids of Gascon pig muscles (LD and BF respectively) were 58.27 and 51.98%, while polyunsaturated fatty acids (PUFA) levels were 5.61 and 14.13% respectively; values similar to those found in Iberian pigs and quite different to usual values in commercial pig breeds. The same trend was found in polar lipids. Both muscles showed a low susceptibility to induced lipid oxidation, in agreement with their fatty acid composition. These results pointed out that meat from pigs of the Gascon breed showed optimal characteristics for dry cured processing.

Meat quality characteristics in different lines of Iberian pigs

Physico-chemical parameters involved in technological meat quality for dry cured processing of four different lines (Entrepelado, Lampiño, Retinto and Torbiscal) of Iberian pigs were studied in the Masseter (MS) and Longissimus dorsi (LD) muscles. The line of Iberian pig significantly affected intramuscular fat content of MS muscle, animals from the Torbiscal line showing lower values. Proportions of several fatty acids of total lipids and polar lipids from the MS muscle were also affected. However, fatty acid composition and total lipids, neutral lipids and polar lipids of LD muscle and neutral lipids of MS muscle were scarcely affected. Lipid oxidation was also unaffected by Iberian pig line, but instrumental colour parameters of MS muscle showed significant variations.

Increased maternal nutrition of sows has no beneficial effects on muscle fiber number or postnatal growth and has no impact on the meat quality of the offspring.

The objective of this study was to examine how increased feed intake of the sow during early to mid-gestation affects sow performance and the muscle fiber number, performance, and technological meat quality of the offspring. Thirty-nine pregnant sows (Landrace x Large White sows mated to Landrace or Large White boars) in their fourth parity were assigned to one of three treatments: 1) the sows were either fed restrictively (control = 15 MJ of NE/d from d 1 to 90, then 24 MJ of NE/d from d 91 to 112, and again 15 MJ of NE/d from d 113 to 115 of gestation); 2) fed ad libitum from d 25 to 50 (A25-50); or 3) ad libitum from d 25 to 70 (A25-70) and as control in the remaining periods. The offspring were weaned at 4 wk of age and had free access to feed from 2 wk of age until slaughter. They were slaughtered litterwise at an average body weight of 104 +/- 14 kg. Estimates for total, primary (P-), and secondary (S-) muscle fiber number; muscle fiber area; and DNA and RNA content were analyzed in semitendinosus muscle (ST) samples from the heaviest, middle, and lightest weight (LW) pigs of each sex within litter selected at slaughter. Technological meat quality traits (pH at 24 h postmortem, drip loss, Minolta color, and pigment) were analyzed in longissimus dorsi muscle. Fiber number, fiber area, and concentrations and content of DNA and RNA of the offspring were not significantly affected by increased maternal nutrition. The ST muscle weight was lower in offspring from A25-50 than control sows (P = 0.019). Average daily gain, carcass weight, and the muscle deposition rate also were numerically lower for A25-50 than control and A25-70 pigs. An interaction between treatment and pig weight was found for muscle deposition rate (P = 0.006), in that LW pigs from treatment A25-50 had a lower deposition rate than LW pigs from control. We found no effect of treatment on the meat quality traits in the offspring. Also, barrows had a higher (P < 0.05) number of P-fibers, higher daily gain, and carcass weight than female pigs. No differences were found on any meat quality traits between sexes. Thus, ad libitum feeding of pregnant sows from d 25 to 50 or d 25 to 70 of gestation did not have any beneficial effect on muscle fiber number and area in the offspring. It seems that maternal ad libitum feeding from d 25 to 50 in gestation had a negative effect on postnatal muscle growth, with especially the LW pigs being affected.

Genomics: Improving Qualitative Characteristics and Value of Meat from Pigs

This article illustrates the main problems of technological and sensory quality encountered in pork production and processing using examples taken from the French pork industry. It describes how in the recent past genomics has allowed a clear improvement of the mean technological quality of pig meat produced in France, and presumably in many other countries, by helping to reduce or eliminate the most striking defects (pale soft exudative – PSE and acid meats). It gives a list of foreseeable applications of genomics to adapt technological and sensory qualities to the requirements of meat end-users, in order to deal with growing market segmentation. Finally, it is concluded that in the future the difficulty will rest much more in the choice of carcass types to produce than in the implementation of the selection tools needed for their production.

Variation of chicken technological meat quality in relation to genotype and preslaughter stress conditions

The present study was aimed at estimating the genetic variability between lines of breast and thigh meat quality (pH decline, color, drip loss, and curing-cooking yield) by comparing a slow-growing French label-type line (SGL) and a fast-growing standard line (FGL) of chickens exposed to different preslaughter stress conditions. The birds were slaughtered under optimal conditions or after exposure to 2 h of transport or acute-heat stress (2 h at 35 degrees C). Relationships between meat quality and stress sensitivity were investigated by measuring struggle during shackling and tonic immobility (TI) duration, 1 wk before slaughter, as an indicator of the basal level of fear of the birds. Although most of the meat quality indicators varied between the 2 lines, differences were muscle dependent. In concordance with a lower ultimate pH, curing-cooking yield of thigh meat was decreased for the FGL birds. In contrast, these birds had a higher curing-cooking yield and a lower drip loss of breast meat resulting from a less rapid pH decline in this muscle compared with SGL birds. Thigh meat characteristics were influenced by both preslaughter stresses, but no significant effects were detected for breast meat. The main effect of heat stress in thigh meat was a decrease of the ultimate pH and led to paler color and lower curing-cooking yield; opposite effects were obtained for transport. Breast meat was much more sensitive to physical activity of birds on the shackle line. Longer durations of wing flapping on the shackle line gave more rapid initial pH decline. Whatever the line, no relationship between TI duration and meat quality characteristics or activity was observed. The present study suggested that SGL birds could be at disadvantage due to more struggle during shackling and accelerated postmortem glycolysis, which is detrimental to the quality of breast meat.

Production Results and Technological Meat Quality for Pigs in Indoor and Outdoor Rearing Systems

The objective of the study was to compare production results and technological meat quality for pigs born outdoors and reared indoors or outdoors during the summer period. A total of 279 pigs was reared in a large pen on deep litter, or outdoors. Daily weight gain and lean meat percentage were higher for pigs outdoors than indoors during year one (864 vs. 841g; 56.9 vs. 55.9%), but were similar for year two (859 vs. 844g; 55.9 vs. 55.6%). Outdoor pigs grew faster when fed ad libitum, but slower during the second phase when restricted, with inferior feed conversion. Most technological meat quality traits (surface and internal reflectance, marbling, pHBF, filter paper wetness, cooking loss and maximal Warner-Bratzler shear force) were similar between rearing systems, whereas pHLD was higher indoors. Total work of Warner-Bratzler shear force was lower in outdoor reared pigs. Maternal sire breed (Duroc or Landrace) and sex (castrate or gilt) did not notably affect meat quality traits. RN genotype had a stronger impact on meat quality than rearing system. It can be concluded from the similarities in production results and meat quality in both systems, that both indoor and outdoor rearing are good alternatives for summer rearing of pigs.

A second mutant allele (V199I) at the PRKAG3 ( RN) locus— I. Effect on technological meat quality of pork loin

The effect of three alleles ( RN −, rn + and a second mutant allele V199I, denoted rn*) at the PRKAG3 ( RN) locus on such meat quality traits as pH, internal reflectance (FOP), Warner–Bratzler shear force, water-holding capacity and cooking loss were studied. M. longissimus dorsi (LD) from a total of 334 crossbreed pigs, entire males and females, Hampshire (H) and Finnish Landrace (L) of three combinations H × LH, LH × H and LH × LH, were used. The PRKAG3 alleles were identified with a DNA test and all possible RN genotypes, RN −/ RN − (23%), RN −/ rn + (24%), RN −/ rn* (33%), rn + / rn + (8%), rn + / rn* (9%) and rn*/ rn* (2%), were found. Water, intramuscular fat, protein and glycogen contents were determined. All the three alleles at the RN locus affected the studied technological meat quality traits of pork loin, except for the internal reflectance 24 h post mortem and the shear force. The RN − allele was dominant over the other two alleles, rn + and rn*, in LD with regard to ultimate pH, water-holding capacity and cooking loss, giving lower ultimate pH and water-holding capacity and higher cooking loss. The rn* allele affected ultimate pH in LD of non-carriers of the RN − allele, giving higher ultimate pH. The RN − allele was also dominant over the other two alleles in residual glycogen content in entire male pigs, but not in female pigs, where the rn* allele had a glycogen-lowering effect. The water content was higher and the protein content lower in LD of all RN −/– animals compared with the other genotypes, while no significant differences were found with regard to IMF content. Water-holding capacity, cooking loss and shear force were higher in LD of entire males compared with females.

Effects of Sex, Feed and Pre-slaughter Routines on Technological Meat Quality in Carriers and Non-carriers of the RN − allele

The aim of this project was to study the effects of feeding system (dry or wet feeding with whey), dietary lysine level and pre-slaughter routines on technological meat quality in entire male, female and castrated male pigs, which were carriers or non-carriers of the RN − allele. The feeding system only affected the yield of processed meat, resulting in lower Napole yield (87.5% vs 89.4%) for meat of whey fed pigs. Further, lower dietary lysine levels resulted in higher drip loss of the meat compared with high dietary levels (5.3% vs 4.8%). Mixing of unfamiliar pigs prior to slaughter led to meat with lower internal reflectance values (28.3 vs 32.2) and glucose+G-6-P concentrations of the meat juice (46.3 vs 49.7 μmol/ml) compared with pen-wise slaughtering. In comparison with non-carriers, RN − carriers had significantly lower ultimate pH, shear force values and water-holding capacity. Mixing of non-carrier pigs prior to slaughter gave higher Napole yield compared with those handled pen-wise. Females had lower ultimate pH and higher Napole yield compared with entire males.

Green hams electrical impedance spectroscopy (EIS) measures and pastiness prediction of dry cured hams

The objective of this study was to assess the value of electrical impedance spectroscopy (EIS) as a predictor of certain dry-cured ham sensory properties in green hams of different technological meat qualities and processed commercially. Measurements of technological meat quality (weight, ham conformation, subcutaneous fat thickness, pH 45 and pH u) and some sensory properties (adhesiveness, hardness, crumbliness, pastiness, fibrousness and saltiness) were carried out on the Biceps femoris (BF) and Semimembranosus (SM) muscles. The electrical parameters, R o, R inf, ratio ( R inf/ R o), F c and α, were obtained with EIS equipment applied to two different regions of the ham at 36 h post mortem (BF and SM). Principal component (PC) analysis was used to describe the relationship between sensory properties and electrical parameters. For BF muscle there were no clear relationships between the electrical parameters and the sensory properties. However, for SM muscle, pastiness was correlated positively with the ratio and F c obtained by EIS. None of the electrical parameters obtained by EIS were able to differentiate between groups of hams classified according to their level of pastiness in the BF muscle. However, in the SM muscle, the origin of the pastiness was related to the use of PSE meat and was predicted by the electrical impedance measurements. The EIS prototype correctly detected 69.2 and 56.0% (for SM and BF muscles, respectively) of the problem hams in terms of pastiness. These results could be of use in the selection of the raw material to reduce the incidence of dry-cured hams with defective texture.

Compensatory growth response in pigs, muscle protein turn-over and meat texture: effects of restriction/realimentation period

AbstractThe present experiment was designed to evaluate the effect of different time spans of ad libitum feeding of pigs prior to slaughter after a period of restricted feeding on performance and texture characteristics of the meat. Te n litters of five pigs (Duroc ✕ Landrace ✕ Large White crosses) were allocated to five feeding treatments (AA, R28A42, R43A27, R52A18 and R60A10) at the age of 70 days. AA-pigs were given ad libitum a concentrate diet from day 70 to slaughter at day 140 (approx. 100 kg live weight). R28A42, R43A27, R52A18 and R60A10 pigs were given food at a restricted level (0·6 of ad libitum) for 28, 43, 52 and 60 days, respectively, followed by ad libitum feeding for 42, 27, 18 and 10 days, respectively, until slaughter at day 140. All pigs that had been given food at a restricted level for a period (R28A42, R43A27, R52A18 and R60A10) showed a compensatory growth response in the subsequent ad libitum period. However, only pigs on ad libitum for a minimum of 27 days prior to slaughter (R28A42 and R43A27) had carcass weights and muscle mass similar to that of the control pigs (AA) at slaughter. The restricted feeding increased meat proportion, whereas the feeding strategies had no effect on technological meat quality traits (pH24, drip loss and CIE-colour traits: L*, a* and b*). During compensatory growth, protein turn-over was increased and positively related to the length of the ad libitum period as indicated by the concentration of elongation factor-2 (eEF-2) (P &lt; 0·10), the activity of µ-calpain (P &lt; 0·01) and the myofibrillar fragmentation index (MFI) 1 day post mortem in m. longissimus dorsi (P &lt; 0·08) and the solubility of collagen (P &lt; 0·01). Although not significant, the shear force at day 1 followed the same pattern of improvement as the MFI. The concentration of eEF-2 increased at a faster rate following transition to ad libitum feeding than did the activity of µ-calpain. This suggests that muscle protein synthesis increases at a faster rate after change to ad libitum feeding and reaches the same level as in the control pigs (AA) before muscle protein degradation. This time lag between the increase in protein synthesis and degradation could explain the compensatory growth response and it also suggests that in order to use the compensatory growth mechanism to improve tenderness, the optimal time of slaughter may not coincide with the period of highest growth rates, but may occur at a later stage, when muscle protein degradation is maximal. For pigs slaughtered at 100 kg live weight, we expect muscle protein degradation to be maximal some time beyond 42 days of ad libitum feeding prior to slaughter.

Compensatory Growth and its Effect on Muscularity and Technological Meat Quality in Growing Pigs

Compensatory Growth and its Effect on Muscularity and Technological Meat Quality in Growing Pigs