The effect of feed withdrawal on broiler blood glucose and nonesterified fatty acid levels, postmortem liver pH values, and carcass yield.

Feed withdrawal should start 5 h before broilers are captured and transported to the processing plant. This practice results in a total feed withdrawal period of about 8 h before slaughter. To check observance of this period at the plant reliably, blood samples were collected at slaughter from broilers. These samples were analyzed for glucose and nonesterified fatty acid (NEFA). Glucose levels decreased, whereas the amount of NEFA increased as a consequence of deprivation. It was found that the decrease in glucose was smaller than could be expected from data in the literature, whereas the level tended to rise again after longer deprivation periods. The increase of the NEFA was lower in males than in females, and the glucose: NEFA ratio also showed a difference between the sexes. Therefore, it was concluded that these blood metabolites were not suitable for use as an indicator of the duration of feed withdrawal. The estimation of liver pH seemed to be a more reliable indicator of the length of feed withdrawal. Longer periods of feed withdrawal resulted in higher ultimate liver pH values, which were 6.10 to 6.20 in full-fed broilers, increasing to 6.60 in livers from broilers deprived during longer withdrawal periods. Further research, however, is needed because broilers in the present study were exposed to minimal amounts of stress. Other carcass characteristics such as slaughter, evisceration, and oven-ready yields matched results previously described in the literature.

The effect of stress, applied immediately before stunning, on pork quality.

The effect on meat quality characteristics of stress, applied during a short period just before stunning, was studied on slaughterpigs (113 boars, 85 gilts). Sexes were kept separately and only pigs that had been stunned correctly were included. Aggressive behaviour during lairage occurred more frequently in boars (about twice) than in gilts. Just before stunning, two animals of the same sex, that were lairaged for an equal period at the slaughter facility, were moved as quietly as possible to the stunning pen, after which one pig was stunned immediately and the other subsequently forced to move through the stunning pen over a period of 1 min. Stress resulted in lower pH values and higher temperatures in the semimembranosus (SM) and the longissimus lumborum (LL) muscles and a higher rigor mortis value of the SM, at 45 min post mortem. Stress affected water holding capacity of the LL negatively at 24 h p.m. Statistically significant interactions were present for sex×stress for several meat quality traits. In general, gilts reacted more strongly to short periods of stress than did boars.

Causes for variation in pork quality.

Research was carried out on 260 pigs that were slaughtered in 12 batches in the slaughter facilities of ID-DLO at Zeist. The practical circumstances were highly standardized. The 'animals' meat quality was good with only little variation; 46 animals showed a 'slightly' aberrant quality and 6 'slight' DFD. Carcasses within the quality categories 'PSE' and 'slight' PSE did not occur. Statistically significant effects on meat quality could be shown for the duration of the resting period before slaughter and the muscular contractions occurring while stunning, shackling and exsanguination, despite the minor variation in pork quality under standardization. A longer resting period before slaughter induced significantly lower temperatures in the m.semimembranosus and the loin at 45 min post mortem and a slightly higher ultimate pH, accompanied by a somewhat darker colour (24hr post mortem). A connection between the animal's behaviour at the fattening station and ultimate pork quality could not be shown. The same counts for fighting in the resting pen of the slaughter house and the pig's behaviour in the stunning area. Muscular contractions during and after stunning had a negative effect on pork quality, causing a more rapid drop in pH, a faster development of rigor mortis and a reduced water holding capacity. An imperfect electrical stunning procedure caused an increase in muscular contractions.

Predictive value of slaughterhouse measurements of ultimate pork quality in seven halothane negative Yorkshire populations.

An experiment with 1969 pigs, belonging to Yorkshire sire lines, was set up in cooperation with seven Dutch breeding organizations. The pigs, which were claimed to be halothane negative, were slaughtered in weekly batches. Light reflectance was determined with the Hennessy Grading Probe (HGP) and Fibre Optic Probe (FOP), in addition to pH(1) and rigor mortis at 45 min post mortem (p.m.). Further meat quality determinations were performed either in the slaughterhouse at 20 h p.m., or in the laboratory at 24 h p.m.. At first sight, both the scatter of light (HGP-PSE, FOP) and pH, measured at 45 min p.m., appeared to be indicative of the ultimate meat quality score. More accurate analyses, however, showed that the value of reflectance values is limited and less suitable in comparison to pH(1), especially with reference to the prediction of ultimate quality characteristics of water holding capacity. The correlations for pH(1) with drip loss were rather consistent, ranging from -0·34 to -0·52 per breeding population. In contrast, HGP-reflectance values ranged from -0·27 to 0·34, while those based on FOP(1) had a range from nearly zero (0·02) to 0·20. The proportion of variation (R(2) × 100%) in drip loss, explained by a set of slaughterline measurements, ranged from 13 to about 28% per breeding population. The use of measurements carried out at 20 h p.m. improved the R(2) × 100% for drip loss to a range from 50 to 62%.

Chilling pig carcasses: Effects on temperature, weight loss and ultimate meat quality.

Effects of conventional (4°C, air velocity 0·5 m/s) and forced chilling at -5°C (120 min) or -30°C (30 min) with air velocities of 1, 2 or 4 m/s, followed by conventional chilling till 24 h post mortem on temperatures, meat quality and weight losses, were studied. Experiments were carried out in six batches of six slaughter pigs each (crossbred gilts, weighing 105-110 kg. The subcutaneous temperature decreased very rapidly to values below 0°C when 'ultra' rapid chilling (-30°C) at high air velocities (4 m/s was used. Immediately after rapid chilling, when the carcasses were railed into a conventional chiller, the subcutaneous temperature increased above the air temperature, after which the decline in temperature was continued. Temperature inside the biceps femoris muscle decreased from the start of chilling rather slowly according to an asymptotic curve until ultimate values of 4°C were reached. Theoretically calculated temperatures during slaughter and chilling were comparable with the measured values; indicating that a finite-element calculation method in combination with a cylindrical model for heat transport can be used to predict muscle temperatures for various chilling regimes. Losses in carcass weight, 24 h after conventional and forced chilling at -5°C, were about 2%. After 'ultra' rapid chilling (-30°C) the losses were reduced to 1·3% when air velocity was increased to 4 m/s. Meat quality of the longissimus lumborum muscle was not significantly affected by the various chilling regimes except for the variables related to tenderness. The Warner-Bratzler shear forces were higher (P < 0·05) together with shorter sarcomere lengths (P < 0·10) after 'ultra' rapid chilling at a high (4 m/s) air velocity, indicating an increased risk of cold shortening.

'Scharrel' (free range) pigs: Carcass composition, meat quality and taste-panel studies.

Carcass conformation, meat quality, fatty acid patterns of backfat and sensory quality characteristics (tenderness, juiciness, smell and taste) of scharrel (free range) pigs and animals from intensive fattening systems were compared. Both groups of pigs consisted of 80 animals, which were slaughtered in batches of 20 pigs per group. The measurements included hot carcass weight, HGP, pH and FOP measurements and a score for intrathoracal fat deposition, all performed early post mortem, and marbling, colour, drip and cooking loss and Warner-Bratzler shear force measurements in loin chops after 1 and 3 days of storage at 4°C. Furthermore, 25% of the carcasses were used in taste-panel analyses. The feed rations used for these 25% of the pigs and their backfat samples were analysed for fatty acid patterns. The overall meat quality of scharrel pigs was not significantly different from that of pigs from intensive fattening systems. W-B shear force values of scharrel pigs were slightly higher. However, this did not coincide with differences in panel tenderness scores. The analytical panel assessed minor differences in taste and smell. The inconsistency of the descriptions concerning these differences did not allow any conclusions. An increase in the amount of linolenic acid was observed in the scharrel pigs' backfat.

The effectiveness of examining early post-mortem musculature to predict ultimate pork quality.

Variations in pork quality reflect value differentials. However, only when they can be easily, accurately, rapidly and cost-effectively detected, can swine producers expect to eliminate poor quality from their herds through genetic selection, and can the industry be expected to take the necessary environmental precautions to prevent poor quality. This study was designed to assess the effectiveness of various techniques thought to predict ultimate pork quality through the examination of the physical and chemical properties of early post-mortem (PM) musculature. Based on stiffness and pH 30, 285 carcasses were selected. This selection procedure ensured a wide variation in ultimate quality. Using 12 instruments simultaneously, temperature, stiffness, electrical properties, lightness properties, and pH 45 of the early PM longissimus thoracis et lumborum were recorded to predict ultimate quality. Based on post-rigor light reflection and water-holding capacity (WHC), quality was assigned to one of five arbitrary groups. Of all techniques tested, the only one with any potential for adequate prediction of quality categories was pH 45. Combination of different techniques did not significantly increase predictive values. For predicting quality of single carcasses, pH 45 should not be considered satisfactory. However, based on our success in selecting carcasses representing quality variation for this study and the results obtained from the study, using pH 45 and muscle stiffness to select groups of carcasses is feasible. We conclude that the techniques used early post mortem are not appropriate for predicting ultimate pork quality for single carcasses. At present we recommend that only post-rigor muscle be considered, and that ultimate pH, light reflection and a measure of WHC should be used.

The effect of scalding on subcutaneous and ham temperatures and ultimate pork quality.

Scalding of pig carcasses (n = 34) at 60°C for a period of at least 5·5 to 7·5 min gave satisfactory dehairing results, with the exception of autumn hair for which a longer period (9 mins) was required. Temperature curves were recorded for a subcutaneous position in the ham (n = 26) between the rind and the underlying fat layer. These showed a curve starting at about 30·8°C and increasing to an asymptotic value of 53°C during scalding. Results of calculations with a finite element model of a flat layer of muscle covered with a layer of 1·0 cm fat broadly showed the same temperature increase at about 0·5 cm below the surface as the actual values measured. Immediately after dehairing, about 1·5 mins after finishing scalding, the subcutaneous temperature had already dropped to 46·1 ± 3·0°C, which was considerably higher than the muscle temperature at the same position at a depth of 5 cm under the skin (40·6°C). The heat removal and temperatures during the cooling period after scalding were also calculated. It can be concluded that the increase in temperature due to scalding has only a minor influence on muscle temperature and that meat quality (pH, FOP) is not affected.

Marbling, intramuscular fat and meat colour of Dutch pork.

The amounts of intramuscular (i.m.) fat in the lean meat of the lumbar region of 21 slaughterpigs have been determined according to the Soxhlet method as a reference, and compared with those determined with the faster Foss-let procedure. These methods were highly correlated, over the lower range of fat concentrations (0·30-4·35%) studied. Although the Foss-Let values were on average slightly lower than the Soxhlet values, the Foss-Let procedure can be recommended for the determination of i.m. fat in pork. Furthermore, chemically determined i.m. fat was found to be significantly correlated with marbling. The sensory evaluations of pork colour were significantly correlated with each other and with the instrumentally determined colour lightness.

Differences in quality characteristics of normal, PSE and DFD pork.

Differences in water-holding capacity, colour and tenderness/toughness were studied in 21 pork loins belonging to three quality categories, i.e. dark firm dry (DFD), normal and pale soft exudative (PSE). The division into the three groups was based upon the ultimate pH-values of the loins (< pH 5·5, pH 5·5-6·0, pH > 6·4). The PSE loins were characterized by a poor waterholding capacity, higher cooking loss and paler colour in contrast to the DFD category. The normal loins took an intermediate position. Neither sarcomere length, determined on fresh muscle tissue, nor Armour tenderometer values showed significant differences between the various quality categories. This was in contrast to the Warner-Bratzler (W-B) shear force values, determined on cooked loins, which had the lowest values in the DFD category. A strong relationship between the W-B values and the cooking losses was found. It was concluded that neither sarcomere length nor Armour tenderometer measurements were able to predict the shear force values of cooked pork loins.

The effect of replacement of 0.30% sodium chloride by 0.43% sodium bicarbonate in rations of fattening pigs on leg weakness, osteochondrosis and growth.

The effect of replacing dietary sodium chloride by sodium bicarbonate on leg weakness, osteochondrosis and growth in young fattening pigs was studied in two experiments using 104 and 126 animals. The experimental pigs were fed 0.43% dietary sodium bicarbonate, which replaced the sodium chloride (0.30%), was present in the diets of the control groups. It was found that the clinical symptoms of leg weakness could be improved significantly in the experimental group which received bicarbonate. No positive effects on osteochondrosis, however, could be shown. The treated animals even tended to have more severe osteochondral lesions. Reasons for the negative tendency are discussed. Daily weight gain and food conversion were not influenced by the experimental bicarbonate diet excluding a chloride deficiency. Differences in carcass grading were not significant, although barrows fed the NaHCO3-containing diet tended to score better, while the carcass quality of the experimental gilts was slightly less in comparison to the control animals.

The use of filter paper to estimate drip loss of porcine musculature.

Two simple, accurate, rapid and economical methods for determining variations in drip loss of lean, prepackaged, post-rigor porcine musculature during storage have been developed. Laboratory grade filter paper having a 45 mm diameter was placed on the cut surface of the muscle (after 10-15 minutes' exposure) and scored for wetness (0 to 5) within 3 s or weighed for fluid accumulation. The tests on 40 randomly selected longissimus muscles that appeared to represent 'normal' quality characteristics proved to be nearly perfectly and positively correlated to % 48 h drip loss. Statistically, the relationship was non-curvilinear and, when regression equations were used to predict drip losses on a separate group of 27 muscles having considerable variation in quality, the correlations between the predicted and actual values were nearly perfect (r = 0·97 for score and 0·95 for weight). These two methods have not been compared to other, more sophisticated, ones currently used, but the results of this investigation suggest that the two methods may be useful to the meat industry, especially for practical applications.

A comparison of methods to estimate water-holding capacity in post-rigor porcine muscle.

Water-holding capacity (WHC) of muscle is important because it affects both qualitative and quantitative aspects of meat and meat products. For assessment of WHC under field and laboratory conditions, there are several methods available, but they have not been compared in a single experiment to determine accuracy and repeatibility. The Longissimus dorsi from each of 28 porcine loins representing three distinct levels of WHC (DFD, PSE, normal) was separated into eighteen parts that were randomly assigned to individual methods. The following methods were compared: Grau-Hamm and Braunschweiger-Gerät filter paper press techniques using five approaches of evaluation for each method; transmission per cent; swelling due to added water; centrifugation; 48-h fresh and cooked shrink: imbibition of surface fluids, kapillar volumeter, permittivity; and score or weight of surface fluids accumulating on filter paper. Results indicated that most methods separated the three muscle types. However, the cooking loss tests failed to differentiate between PSE and normal samples, and the transmission, imbibition and pressed fluid methods did not always distinguish between DFD and normal. The tests that appeared to be most reliable included drip loss originating from size-standardized samples, swelling of homogenized samples by added water and absorption of surface fluids on filter paper.

[Leg disorders in swine: clinical changes attributable to the type of flooring]. / Beengebreken bij varkens: klinische veranderingen die zijn toe te schrijven aan het type vloer.

Clinical symptoms of leg weakness were assessed in three groups of pigs, consisting of sixty-four, thirty-two and thirty-two animals respectively at four-week intervals during the fattening period. The animals of the various groups were housed in pens (eight pigs in each pen) with one of three types of flooring, viz. a concrete slatted floor, a floor of recycled plastic slats, or a perforated floor of polyurethane. The pigs housed on concrete slatted floors showed less severe clinical symptoms of leg weakness compared to the animals housed on floors of recycled plastic slats. The third group of pigs, those on the perforated floor of polyurethane, showed symptoms of internediate severity. The claws of the pigs in the most severely affected group were significantly longer than those of the pigs in the two other groups. Moreover, the distal parts of the limbs of these animals were much weaker, and the proportion of lame animals in this group was larger compared with that of the two other groups.

Do gilts and barrows react similarly with respect to leg weakness and osteochondrosis?

Clinical and pathological data concerning the degree of leg weakness and severity of osteochondral lesions in gilts and barrows have been compared. It became clear that the pathological condition of the distal part of the ulna and the medial femoral condyle of gilts was less severe than that of barrows. The clinical symptoms of leg weakness in gilts also tended to be less severe than those in barrows.

Acid-base parameters in venous blood of pregnant and non-pregnant Dutch Friesian and Dutch Red and White cows.

Acid-base values in venous blood of pregnant and non-pregnant cows belonging to the Friesian (FH) and the red-and-white (MRIJ) breeds were compared. Differences between the breeds were not found. Pregnancy seemed to cause a slight decrease in the base excess value and in the standard bicarbonate concentration.

Osteochondrosis in six breeds of slaughter pigs. I. A morphological investigation of the status of osteochondrosis in relation to breed and level of feeding.

The severity and extent of osteochondral lesions have been examined, macroscopically, radiographically as well as histopathologically, in six different breeds of pigs (Belgian Landrace (B), Duroc (D), Dutch Landrace (N), Dutch Yorkshire (G), Hampshire (H) and Piétrain (P)). In these pigs three different levels of feeding were used. Duroc pigs had significantly more severe lesions in the fore limbs than Dutch Landrace (N), Dutch Yorkshire (G), Hampshire (H) and Piétrain (P) pigs, while Belgian Landrace pigs (B) had significant more severe lesions than Dutch Yorkshire (G) pigs. The differences between breeds related more to the degree of severity of the lesions in the articular surfaces of the distal humerus and proximal radius-ulna and in the distal ulnar growth plate than to the presence of the lesions per se. In the hind limbs Belgian Landrace pigs (B) had significantly more severe osteochondral lesions than all other breeds, while Dutch Landrace pigs (N) had significantly more severe lesions than Duroc (D), Dutch Yorkshire (G), Hampshire (H) and Piétran (P) pigs. Pigs with the highest growth rate showed significantly more severe osteochondral lesions in the distal ulnar growth plate and in the medial femoral condyle than pigs with a more restricted growth rate.

Osteochondrosis in six breeds of slaughter pigs. II. Data concerning carcass characteristics in relation to osteochondrosis.

Coefficients of correlation have been calculated between morphological lesion scores of osteochondrosis that were made on the bones of porcine fore and hind limbs and some carcass characteristics. It was found that carcass length, as well as the relative weights of the hams were significantly correlated with the lesions that were observed in the proximal site of the femur and the medial femoral condyle. Despite these significant correlations, the values of the correlation coefficients were too small to be of any use for selection purposes. This applies the whole animal population, consisting of 6 breeds of pigs. It is shown that the coefficients of correlation between the morphological lesion scores of the femur and the relative weights of the hams in some of the individual breeds were much higher, implying a possibility for the prediction of osteochondrosis based on carcass characteristics.

Osteochondrosis in six breeds of slaughter pigs.

Summary The severity and extent of osteochondral lesions have been examined, macroscopically, radiographically as well as histopathologically, in six different breeds of pigs (Belgian Landrace (B), Duroc (D), Dutch Landrace (N), Dutch Yorkshire (G), Hampshire (H) and Piétrain (P)). In these pigs three different levels of feeding were used. Duroc pigs had significantly more severe lesions in the fore limbs than Dutch Landrace (N), Dutch Yorkshire (G), Hampshire (H) and Piétrain (P) pigs, while Belgian Landrace pigs (B) had significant more severe lesions than Dutch Yorkshire (G) pigs. The differences between breeds related more to the degree of severity of the lesions in the articular surfaces of the distal humerus and proximal radius-ulna and in the distal ulnar growth plate than to the presence of the lesions per se. In the hind limbs Belgian Landrace pigs (B) had significantly more severe osteochondral lesions than all other breeds, while Dutch Landrace pigs (N) had significantly more severe lesions than Duroc (D), Dutch Yorkshire (G), Hampshire (H) and Piétran (P) pigs. Pigs with the highest growth rate showed sginificantly more severe osteochondral lesions in the distal ulnar growth plate and in the medial fe,moral condyle than pigs with a more restricted growth rate.