Muscle Ultimate pH Research Articles

Managing variation to produce quality in farm products

The fundamental influence of variation on the production of quality products is reviewed. The partitioning of this variation into that which is controllable on the farm and that which is uncontrollable on the farm is discussed. The effectiveness of an on-farm quality assurance programme depends on the level of variation in a trait than can be controlled by farm management practices. A simple graphical tool that can be used on farm and is suitable for monitoring performance through time is the cusum control chart. This chart plots the cumulative sum of deviations from target performance. It is designed to identify the occurrence of problems in production on farm for which effective management action may be taken. The operation of a cusum chart for monitoring a quality assurance programme on farm is illustrated, using as an example the control of ultimate muscle pH in cattle. The cusum chart in this example is designed and operated using measurements supplied by a meat processor which were made on the muscle following slaughter. Keywords: controllable variation, cusum chart, farm monitoring, quality assurance, uncontrollable variation

Effects of prolonged release recombinant porcine somatotropin and dietary protein on the growth, feed efficiency, carcass yield and meat quality of pigs

The effects of prolonged release recombinant porcine somatotropin (rpST) and dietary protein were tested in 108 Lacombe pigs, allocated to control or rpST treatments at 70 kg and fed isoenergetic diets containing one of three protein levels (14, 17 or 20% CP). Recombinant derived porcine somatotropin was implanted in the ear weekly (Monsanto Agricultural Co., St. Louis, #CP 115409, 12 mg wk−1). The control animals were given a weekly sham injection for a minimum of 4 wk. The prolonged release rpST had no effect on average daily gain (ADG, P > 0.05), but did reduce both the feed:gain ratio (F:G, P < 0.07) and dressing percentage (7 g kg−1 reduction, P < 0.05). Although both the fat thickness (10th rib) and kidney fat were reduced 5.6 and 13.9%, respectively, the absolute organ weights for kidneys, liver, lungs and gastrointestinal tract increased between 5 and 10% in prolonged release rpST treated pigs compared with control pigs (P < 0.05). Bone also increased by 6 g kg−1 (P < 0.05) in prolonged release rpST treated pigs, but carcass muscle or fat proportions were not different. Prolonged release rpST caused a higher ultimate muscle pH, moisture content and shear value (P < 0.06) and lower drip loss and expressable juice (P < 0.05) compared with meat from control carcasses. Increasing the dietary protein had no effect on ADG, but did improve the F:G ratio (P < 0.05). Carcass dressing proportion decreased with increasing protein level, but carcass lean content increased 5 g kg−1 for every 3% increase in crude protein. Simultaneous reductions in carcass fat, marbling and drip loss were observed (P < 0.05) as protein level increased. The data suggest that the current prolonged release rpST (12 mg pellets) shows marginal effects on growth and carcass composition. Some nutrient redirecting was apparent and improvements in the processing value of pork may result. Key words: Porcine somatrotropin, prolonged release, growth, diet, carcass, meat quality

The effects of plane of nutrition and slaughter weight on the performance and carcass composition of continental beef bulls given high forage diets

AbstractBulls (½ Blonde d'Aquitaine ⅜ Charolais) were used in a 2 × 3 factorial design experiment with two planes of nutrition in the finishing period and three slaughter weights. High and low planes of nutrition were based on diets with similar forage to concentrate ratio (0·40 of dry matter (DM)) offered ad libitum or at 0·78 of ad libitum DM intake at equal live weight respectively. The target slaughter live weights were 550, 625 and 700 kg. Twelve bulls were taken to each slaughter point and an additional five animals were killed as a pre-experimental slaughter group. Mean initial live weight was 412 (s.e. 5·3) kg at a mean age of 342 (s.e. 2·5) days. No significant interactions were found between the main factors. For the high and low planes, live-weight and estimated carcass gains were 1251 and 989 (s.e. 47·7), and 816 and 668 (s.e. 35·3) g/day respectively, the reduction in gains being similar to the proportional degree of nutritional restriction. Plane of nutrition had no effect on live-weight or carcass gain per unit of energy intake. The low plane of nutrition produced significant decreases in body cavity fat depots, subcutaneous fat in the sample joint and increased the proportions of both saleable beef and high-priced joints in the carcass.With increase in slaughter weight, energy intake per unit of live weight0·75 and rates of both live-weight and carcass gain tended to decline. The dressing proportions were 583,579 and 609 (s.e. 9·1) g/kg for the slaughter live weights of 550, 625 and 700 kg. Carcass conformation improved while fat depots in the body cavity and estimated concentration of separable fat in the carcass increased with increase in slaughter weight, and both estimated lean and bone concentrations decreased. Forequarter as a proportion of total side tended to increase with increase in slaughter weight. Slaughter weight had no effect on concentration of saleable meat or ultimate pH of carcass muscle. It is concluded that bulls of this genotype can be taken to high slaughter weights on diets having a relatively high proportion of forage as grass silage, with high rates of growth and acceptable carcass leanness.

Carcass and meat quality of finishing Friesian steers fed the β-adrenergic agonist L-644,969

The effect of the β-adrenergic agonist L-644,969 on selected parameters of carcass and meat quality was examined in Friesian steers. Four groups of 18 steers were individually offered ad libitum a pelleted diet that contained 0, 0·25, 1·0, or 4·0 ppm L-644,969 for 12 weeks prior to slaughter. L-644,969 quadratically increased carcass weight (3·7, 9·3, and 8·5%, P < 0·001) and altered the distribution of lean meat such that a greater (0·3–5%; P < 0·01) proportion was in the more valuable cuts. There were no effects of L-644,969 on carcass-chill loss and on the water-holding capacity of the longissimus thoracis et lumborum (LTL) muscle. The intramuscular-fat concentration of the LTL was decreased (27–50%; P < 0·01) and the effects on muscle ultimate pH were small and commercially unimportant. Fibre-optic-probe measurements of the LTL indicated darker ( P < 0·01) meat due to β-agonist treatment. L-644,969 increased the shear force required to cut through cooked muscle from the LTL (159%, 209%, and 217%, P < 0·001). It is concluded that L-644,969 treatment improved the quantity and distribution of lean in the carcass but impaired meat quality, primarily through a reduction in tenderness.

Muscle Characteristics and Meat Tenderness of Cimaterol‐fed Lambs

ABSTRACTShear values of loineye muscle from (cimaterol) CIM‐fed lambs were 32 and 28% greater than those of controls at 1 and 8 days postmortem. The CIM‐fed animals showed lower (p&lt;0.01) cytochrome oxidase activity, lower (p&lt;0.01) initial glycogen, and higher (p&lt;0.05) 24 hr pH in the longissimus and semimembranosus muscles. Intramuscular fat of treated lambs (2%) was lower (p&lt;0.01) than that of controls (5.1%), whereas muscle protein concentration was greater (p&lt;0.05). The decreased aerobic capacity, lower intramuscular fat, lower initial glycogen, higher ultimate muscle pH (5.8–6.2) with subsequently reduced postmortem proteolysis and higher protein concentration all appeared to contribute to greater meat toughness of CIM‐fed lambs.

A comparison of growth, food efficiency and carcass characteristics of single and twin beef calves derived by embryo transfer

AbstractAn experiment was designed to examine the interaction between birth status and plane of nutrition of calves in relation to postnatal and lifetime performance. The experiment was a 2 × 2 × 2 factorial arrangement of birth status (single and twin), plane of nutrition from birth to 16 weeks (period 1) and plane of nutrition from 16 weeks to slaughter at a mean live weight of 530·4 (s.e. 0·13) kg (period 2). The planes of nutrition were control and low with metabolizable energy (ME) intakes of 32·1 and 21·4 (s.e. 0·46) MJ/day from birth to 16 weeks, and 73·9 and 64·1 (s.e. 0·95) from 16 weeks until slaughter. The birth weights of the single and twin-born calves were 47·2 and 39·7 (s.e. 0·90) kg respectively. There was no interaction between birth status and plane of nutrition in either main period and by 40 weeks of age the live weights of the twin calves were similar to those of the single-born calves. For period 1 plus period 2 the live-weight gains per unit of ME intake were 12·4 and 13·1 (s.e. 0·28) g/Mf for single and twin-born calves respectively. Although twins had slightly poorer carcass conformation and higher proportion of bone in the carcass, the concentrations of saleable meat and high-priced joints in the carcass were similar. Birth status had no effect on the ultimate pH of muscle. It is concluded that viable twins have similar beef producing potential to single-born calves.The control and low planes of nutrition imposed during the periods from birth to 16 weeks and 16 weeks to slaughter produced live-weight gains of 822 and 573 (s.e. 31·0) g/day, and 857 and 690 (s.e. 12·6) g/day respectively. Calves which had been on the low plane during the initial period had a compensation index of 0·30 by 64 weeks of age. Carcass measurements were not affected by the plane of nutrition during either period. Steers grew faster than heifers, had lower area o/m. longissimus dorsi but less separable fat and more bone in the forerib joint than heifers at equal carcass weight.

Moderate indoor exercise: effect on production and carcass traits, muscle enzyme activities and meat quality in pigs

AbstractThe effects of moderate indoor exercise (running/walking up to 735 m, 5 days/week) on performance, muscle enzyme activities, carcass traits and technological meat quality were studied in 20 crossbred slaughter pigs during the fattening period. Non-exercised pigs were kept only in their pens and consisted of littermates (no. = 20). Blood samples for lactate analysis and muscle samples from m. longissimus dorsi (LD) and m. biceps femoris (BF) for analyses of the activities of lactate dehydrogenase (LDH), citrate synthase (CS), 3-OH-acyl-CoA dehydrogenase and hexokinase were collected at exsanguination. The initial pH was measured approximately 1 min after exsanguination in LD and BF. The carcasses were partially cut and then the back and ham were dissected into individual muscles. Carcass length and presence of osteochondrosis were recorded. Technological meat quality parameters measured were: surface reflectance, water-holding capacity, intramuscular fat (IMF), crude protein, dry matter, ash content, shear force, ultimate pH, pigment content and extractability of muscle proteins.In comparison with the non-exercised pigs, the exercised pigs had slightly shorter carcasses, paler meat and higher drip loss values in LD and, in BF, a lower proportion of IMF and dry matter and higher pigment content. The CS and LDH activities differed between LD and BF muscles, as also did many of the technological meat quality traits.

31P NMR study of post mortem changes in pig muscle

The rate and the extent of post mortem pH changes in pig muscle largely determine pork quality. Fast pH fall combined with low ultimate pH leads to pale soft exudative (PSE) meat; high ultimate pH leads to dark firm dry (DFD) meat. Post mortem metabolism was studied in pig muscle using 31P NMR. Fifteen pigs, i.e. 7 Large White pigs and 8 Pietrain pigs, were used. Five pigs of each breed were slaughtered, taking care to minimize preslaughter stress. The other pigs (3 Large Whites and 2 Pietrains) were injected with 0·1 mg adrenaline per kg liveweight before slaughter, in order to increase meat ultimate pH. All the animals were killed by electronarcosis and exsanguination. Three of the adrenaline-treated pigs (1 Large White and 2 Pietrains) gave meat with ultimate pH above 6 (DFD meat). The pigs with normal muscle ultimate pH, i.e. 6 Large Whites and 6 Pietrains, had very variable rates of post mortem muscle metabolism (pH at 30 min after slaughter: 6·17–6·85 in Large Whites; 6·04–6·23 in Pietrains). The relationships between pH and ATP changes were similar in all pigs showing normal muscle ultimate pH, whereas ATP disappeared at a high pH value (on average pH 6·4) in pigs with high ultimate pH. The course of post mortem biochemical changes in a given animal could be predicted rather well by examination of a single 31P NMR spectrum obtained around 30 min after death. At this time, muscle with a low rate of metabolism simultaneously showed medium to high pH, high ATP content (4–6·8 μmol/g) and rather low Pi content (6–14 μmol/g); muscle with a fast rate of metabolism (PSE-prone muscle) had low pH, low to medium ATP content (1·1–4 μmol/g) and generally high phosphomonoester (PME) content (9–23 μmol/g); muscle with high ultimate pH (DFD-prone muscle) had high pH, low PME content (4–8 μmol/g) and high Pi content (22–27 μmol/g).

The relationships between glycogen stores and muscle ultimate pH in commercially slaughtered pigs

Small samples of liver and m. adductor (AD) were collected within 45 minutes of death from the carcasses of a total of 604 pigs killed at three bacon factories. Glycogen concentrations were measured and part of the muscle sample allowed to complete post-mortem glycolysis in order to estimate ultimate pH (pHu) values. Liver glycogen levels were also used to predict overall food withdrawal times. Muscle glycogen concentrations ranged from 2·2 to 15·3 mg/g, liver glycogen from 0·01 to 50·7 mg/g and pHu in the AD from 5·51 to 6·76. The overall average predicted fasting time was 16·5 ± 0·54 (sem) hours and 22% of pigs had pHu values in the AD>6·2 indicative of potentially dark, firm, dry meat. Muscle glycogen concentration was positively correlated with liver glycogen ( r = 0·27, P<0·01) and negatively correlated with predicted fasting time ( r = −0·30, P<0·001). The pHu in the AD was negatively correlated with liver glycogen ( r = −0·-34, P<0·001) and positively correlated with predicted fasting time ( r = −0·37, P<0·001). Therefore, pigs which had reduced concentrations of glycogen in their livers, indicative of longer food withdrawal times before slaughter, tended to have less glycogen in their muscles and a higher pHu in the meat.

Pre‐ and Post‐Rigor Sectioned and Formed Beef Steaks Manufactured with Different Salt Levels, Mixing Times and Tempering Times

ABSTRACTThis study was designed to identify processing parameters necessary for the incorporation of pre‐rigor beef in sectioned and formed steaks. Meat logs were prepared from pre‐ or post‐rigor beef muscle with 0.0, 0.5 or 1.0% salt, mixed for 0, 6, 12 or 18 min, frozen and tempered to —3°C. Logs were pressed and cleaved after 0, 24, 48 or 72 hr tempering. Tempering at ‐3°C resulted in sufficient metabolic activity (as measured by pH and R‐value) to deplete the ATP content of pre‐rigor muscle. The presence of salt hastened the onset of rigor, maintained a higher ultimate muscle pH and improved cooking yields, bind (adhesion) and tenderness. Longer mixing times enhanced bind. These data suggest that, with appropriate modification in the processing procedure, pre‐rigor muscle can be incorporated into sectioned and formed products.

Effects of Ad Libitum, Maintenance and Sub-Maintenance Feeding and of Compensatory Growth on some Biochemical Properties of Muscle from Weanling Rabbits

Weanling male rabbits were fed either: 1) a complete diet ad libitum (control); 2) a maintenance diet; or 3) a sub-maintenance diet. After 20 days, half of each group was slaughtered and the remainder was placed on treatment 1 until they achieved the same body weights as the controls (about 30 more days), when they were also killed. Body organs, including livers, hearts, lungs and kidneys, were significantly reduced in weight by nutritional stress. Maintenance and sub-maintenance feeding resulted in increases in ultimate muscle pH, water content and alkali-soluble and -insoluble stromal proteins. The intracellular proteins, especially the myofibrillar fraction, decreased markedly, depending on the degree of nutritional stress. Swelling of the stromal proteins was less for the underfed rabbits, indicating that nutritional stress increased the number of acid-stable cross-linkages. Calcium-induced contraction was not effected by any of the nutritional treatments. Blood enzymes were not affected by nutritional stress from the standpoint of their multiple molecular forms, mobility or band profiles. All differences in muscle characteristics disappeared during compensatory growth except for the increased amount of alkali-insoluble stroma protein. The concepts of labile, mobilizable and fixed body proteins are discussed.sub-maintenance maintenance protein depletion muscle protein

The administration of sugar solutions to pigs immediately prior to slaughter. 3. Effect on bacon yield

ABSTRACTTwo field trials were conducted with 138 and 123 bacon-weight pigs respectively from one farm to determine the effect on bacon yield of feeding the animals sugar solutions prior to slaughter. Three treatments were tested: immediate slaughter on arrival at the abattoir; lairage overnight with access to water only (15 h); and overnight lairage with access to a sugar solution (6 h) followed by water only (9 h) prior to slaughter. A glucose syrup solution was used in one trial and a sucrose solution of similar hexose-equivalent concentration (550 g/kg) in the other. Access to either of the sugar solutions, relative to water only or immediate slaughter, increased bacon yield. This was entirely due to glucose-fed pigs having a higher carcass yield (2·3 % and 1·5 % respectively) and a trend in this direction for the sucrose-fed animals (0·9% and 1·0% respectively). Carcasses of glucose-fed pigs actually gained less weight than those of their counterparts during the curing process, but this did not occur with the sucrose solution. Access to sucrose relative to water only and immediate slaughter increased liver weights by 32% and 42% respectively. Lower hepatic responses were obtained with glucose syrup (18% and 12%). Both sugar solutions reduced muscle ultimate pH (0·1 to 0·2 unit) relative to water only in overnight lairage.

The administration of sugar solutions to pigs immediately prior to slaughter 2. Effect on carcass yield, liver weight and muscle quality in commercial pigs

ABSTRACTThree field trials were undertaken to determine the influence of feeding sugar solutions to pigs immediately prior to slaughter on carcass yield, liver weight and muscle quality. In the first, which involved 168 pigs of 85 to 95 kg live weight, provision of a glucose syrup solution in lairage (4 h) followed by water (12 h), compared with water-only (16 h) increased carcass yield (3%) and liver weight (27%) and reduced muscle ultimate pH (0·1 to 0·4 unit). When water was not made available after consumption of the sugar there was no response in carcass yield. In the second trial conducted with 169 pigs of 110 to 125 kg live weight, and involving the same treatments as in Trial I, except that sugar was provided for a longer period (6 h), corresponding responses in carcass yield, liver weight and muscle ultimate pH were +2·7%, +24% and a decrease of 0·2 to 0·3 units. In both trials responses to sugar feeding were less when compared with pigs slaughtered shortly after arrival at the abattoir. In the final trial, which also involved heavy pigs (88), access to a glucose syrup solution (9 h), but not a sucrose one, followed by water (8 h), relative to water-only in lairage, improved carcass yield (1·1%). Liver weight was increased with glucose (34·2%) and markedly so with sucrose (49·7%) and both sugars reduced muscle ultimate pH (0·1 to 0·6 units).

The administration of sugar solutions to pigs immediately prior to slaughter 1. Effect on carcass yield and some muscle and liver characteristics

ABSTRACTThree experiments, involving a total of 84 pigs of approximately 90 kg live weight, were undertaken to determine the effects of feeding sugar solutions immediately prior to slaughter on carcass yield, liver weights, ultimate pH of the musculature and some chemical characteristics of muscle and liver. In the first, where water-only (14 h) prior to slaughter, or access to a solution of either glucose syrup (12 h) or sucrose (12 h) followed by water-only (2 h) were the treatments, sugar feeding did not influence carcass yield. Liver weight was increased with glucose (39%) and markedly so with sucrose (77%). Livers from sugar-fed pigs had higher glycogen and lower protein concentrations. Glucose reduced muscle ultimate pH (0·2 to 0·4 units) but sucrose had little effect. In the second study various sugars were tested (pure glucose, glucose syrup, sucrose and fructose) and pigs had access to solutions of them for 4 h and water-only thereafter for 10 h prior to slaughter. All sugar treatments increased liver weight and reduced muscle ultimate pH relative to water-only before slaughter. The final experiment involved access to varying amounts of a glucose syrup solution for 4 h followed by water-only (10 h). In comparison with ‘water-only’ prior to slaughter, an intake of some 250 g hexose equivalent reduced muscle ultimate pH (0·2 to 0·3 units) and increased liver weight but a response in carcass yield required in excess of 1000 g hexose equivalent.

A catheptic protease active in ultimate pH of muscle.

A catheptic protease active in ultimate pH of muscle.

Meat production of Friesian steers: the effect of intramuscular fat on palatability and the effect of growth rates on composition changes

The relationship between intramuscular fat percentage and beef quality was investigated in 36 Friesian steers. A poor relationship between fatness and age was ensured by having six groups on rations increasing in concentrate content from 10 to 80%, and then slaughtering the animals after 300 days on these rations at an age of c. 17 months. The group means ranged from 202 to 276 kg for carcass weight, from 2.4 to 6.8 mm for fat depth at the 12th rib, and from 1.5 to 3.4% for intramuscular fat of M. longissimus. Up to 38% of the variation in shear force of M. longissimus could be accounted for by variation in intramuscular fat percentage but in the case of M. rectus femoris and of samples from M. semitendinosus, which had not cold shortened, the relationship between shear force and intramuscular fat percentage was not significant. These results suggest that intramuscular fat may influence tenderness through an effect on susceptability to cold shortening. Taste panel results indicated that with increased intramuscular fat percentage, the flavour, tenderness and overall acceptability of M. semimembranosus roasts improved, but there was little change in juiciness. There was no indication that differences in intramuscular fat percentage were associated with differences in muscle collagen concentration, collagen solubility, ultimate muscle pH, or adrenal cortex activity. Allometric coefficients relating measures of composition to carcass weight indicated that changes in composition with increases in carcass weight were more rapid than those reported for other growth studies. It is suggested that this was because the level of nutrition and carcass weight both contributed to the differences in composition.

Carcass and meat quality of Friesian steers fed on either pasture or barley

Friesian steers were slaughtered as individual animals reached a fasted liveweight of c. 457 kg, after being on either a predominantly cereal diet (12 animals) or a predominantly pasture diet (13 animals) for at least 160 days. Those on the cereal diet grew 31% faster than the animals on pasture so that the latter group was an average of 69 days older. The carcasses of the cereal group were significantly fatter especially with regard to omental fat (+ 54%), intramuscular fat (+ 34% for M. semitendinosus) and dissectable fat from the 9–10–11 rib cut (+ 27%). These differences in composition may have been caused by either differences in growth rate or specific dietary effects. Measurements of tenderness all favoured the cereal group, the largest effect being on cold-shortened M. semitendinosus where the mean shear value was 50% greater for the pasture group. The greater age, lower percentage of intramuscular fat and greater susceptibility to cold-shortening may all be involved in these differences. The groups did not differ in ultimate muscle pH, muscle collagen content or adrenal cortical activity. A laboratory taste panel consisting of 15 members indicated that the flavour of topside roasts from the animals fed on the cereal was more acceptable.

Physical and Biochemical Properties of Porcine Muscle as Affected by Exogenous Epinephrine and Prednisolone

SUMMARY— The effects of intramuscular ante‐mortem epinephrine of prednisolone plus epinephrine injection upon some physical and biochemical properties of porcine longissimus dorsi muscles were studied. Rate of post‐mortem muscle pH decline, ultimate muscle pH, Munsell value and transmission value were not significantly (P &gt; .05) altered by epinephrine or prednisolone plus epinephrine injection. Significantly (P &lt; .05) higher total phosphorylase activity and slightly greater phosphorylase a and % phosphorylase u (% of total phosphorylase activity) were observed in the muscles of epinephrine injected pigs.Neither total phosphorylase nor phosphorylase a was related to rate of pH decline or incidence of pale, soft, exudative muscle development. Muscle concentrations of AMP and IMP were not significantly (P &gt; .05) different between treatments. IMP concentration was highly related to rate of pH fall. Correlation coefficients between longissimus dorsi muscle pH and IMP levels were −.93 and −.94 at 1.5 and 45 min post‐mortem, respectively. Prednisolone treatment resulted in higher initial and ultimate muscle glycogen levels than those from the control or epinephrine injected pigs.