Effect of finishing mode (pasture- or mixed-diet) on lipid composition, colour stability and lipid oxidation in meat from Charolais cattle

Effects of pasture- or mixed-diet finishing mode on colour and lipid stability were measured in meat from Charolais steers, heifers and cows of different ages after refrigerated storage. Meats from pasture- and mixed-diet finished cattle have more or less significant differences in lipid composition which will influence the colour and lipid stability. The mixed-diet finished cattle have about the same proportions of saturated and monounsaturated lipids as pasture-diet finished animals; on the contrary, cattle fed on grass have higher proportions of n-3 PUFA, and to a less extent, of n-6. Finishing diet had an important effect on lipid stability, meat from pasture-finished animals showing significantly lower TBA-RS level than meat from mixed-diet finished animals. Effect of diet was also significant on myoglobin content with a higher content of haeminic iron in mixed-diet finished animals. Effect of diet on colour stability was slight with a beneficial effect of pasture finishing mode, significant only in heifers, and after a meat storage of six days in air.     

The significance of diet, slaughter weight and aging time on pork colour and colour stability

The objective of the present study was to investigate the effect of a diet with a low content of digestible starch, slaughter weight and subsequent aging time on meat colour and colour stability. Pork colour was determined as the extent of blooming of M. longissimus thoracis (LT) and M. semimembranosus (SM) after 1, 2, 4, 8 and 15 days postmortem and as colour stability during a subsequent storage period in air for 6 days. Compared to the control diet, the experimental diet resulted in a significantly lower postmortem muscle temperature (1°C; p<0.0001). Moreover, high slaughter weight (110kg) resulted in a higher postmortem temperature in LT (p<0.001) compared to low weight (85kg). Independent of feeding strategy and slaughter weight, the extent of blooming decreased during the first 2-4 days of aging in LT, however, the effect was more pronounced in meat from experimentally fed pigs and pigs with high slaughter weight. This effect was not seen in SM, where a gradual increase in blooming took place throughout the aging period. The colour stability was found to be superior in aged pork from experimentally fed pigs. The discoloration rate was faster in SM compared to LT. In conclusion, the present study shows that the diet composition can be used as a tool to control meat colour and colour stability in pork.     

Lipid and colour stability of beef from grazing heifers supplemented with sunflower oil alone or with fish oil

The effect of sunflower and fish oil supplementation of grazing heifers on lipid oxidation and colour stability in beef was investigated. For 150 days, heifers were assigned unsupplemented grazing (G) or restricted grazing with 2.5 kg concentrates containing 1250 I.U. -tocopheryl acetate and 290 g sunflower oil (S1), 415 g sunflower oil (S2), 290 g sunflower + 85 g fish oil (FS1) or 415 g sunflower + 85 g fish oil (FS2). Longissimus dorsi muscle was excised 24 h post-mortem and stored at −30 °C prior to analysis. Muscle -tocopherol in the oil-supplemented groups was higher (P < 0.05) than the G group. Lipid oxidation in refrigerated, minced raw or cooked beef was not significantly affected by diet but metmyoglobin was higher (P < 0.05) in raw beef from oil-supplemented groups compared to the G group. Lipid oxidation and metmyoglobin formation increased (P < 0.001) during refrigerated storage. Vitamin E supplementation together with pasture grazing appeared to offset any potential deleterious effect of oil supplementation on lipid and colour stability.     

Effects of dietary humate supplementation to broilers on performance,slaughter, carcass and meat colour

BACKGROUND: This experiment was designed to examine the effect of dietary humate supplementation primarily on pH and colour parameters of carcasses, breast fillets and drumsticks and, secondarily on performance and carcass characteristics in broilers. RESULTS: A total of 240 male broiler chicks (Ross‐308) were randomly allocated to four dietary treatments varying in supplemental humate level (0, 0.1, 0.2 and 0.3% for H₀, H₁, H₂ and H₃). Dietary humate supplementation did not affect performance traits and slaughter, hot carcass weights and yields. Carcass‐related variables (pH, L*, a*, b*, H* and C*) were responsive to the dietary treatments. The L*, a*, b*, and C* values for drumstick muscles were higher than those for breast muscles. Except for the L* value, meat colour parameters changed due to packaging. The a* value was higher and b* value was lower for vacuum packaged breast and drumsticks than for those aerobic packaged. Storage period affected colour parameters; while L*, b*, H* and C* values were higher for drumstick skin than for drumstick meat; the a* value was greater in drumstick meat than in skin. CONCLUSION: pH and colour parameters of carcasses, breast fillets and drumsticks of broilers were improved by dietary humate supplementation. However, responses of broiler performance and slaughter and carcass characteristics were minimal. Copyright © 2008 Society of Chemical Industry     

The eating quality of liver from pigs fed liquid sugar solution prior to slaughter

Livers from pigs fed 4 lb sugar on the day before slaughter contained more than twenty-five times as much glycogen, 1.8 times as much water and were 1 kg heavier than those from control pigs receiving no carbohydrate (averages of six animals). The pigment concentration was lower resulting in an observable paler raw colour. Livers from sugar fed pigs were more tender and juicy but had a weaker flavour.     

Interrelationships between meat quality traits, texture measurements and physicochemical characteristics of M. rectus abdominis from Charolais heifers

Ninety-nine Charolais heifers were used to study the variability of meat quality traits in relation to the physicochemical characteristics of M. rectus abdominis. The heifers of the same trade class were slaughtered at 33 months of age (±4 months) and 381 kg carcass weight (±31 kg). Muscle and bone development scores were evaluated before slaughter. Carcass weight, slaughter age and life average daily gain were recorded. Shear force measurements and meat quality traits were evaluated after 14 days of aging. Some physicochemical characteristics were measured 24 h post-slaughter.Tenderness was correlated with slaughter age (r = −0.31), bone development (r = −0.22) and life average daily gain (r = +0.37). Tenderness was significantly related to total collagen content (r = −0.24), lipid content (r = +0.27) and I myosin heavy chain proportion (r = +0.24). Juiciness was positively correlated with lipid content (r = +0.31) and I myosin heavy chain proportion (r = +0.20). Flavor intensity was correlated with lipid content (r = +0.26) and mean fiber area (r = +0.24). Shear force was correlated with total collagen, lipid and 27K proteasome sub-unit contents. Taking animal characteristics and muscle properties together in a multiple regression analysis increased the explained tenderness variability to 33%. The independent variables listed in order of importance were life average daily gain, total collagen content, bone development, lipid content, I myosin heavy chain isoform proportion, shear force of broiled meat and slaughter age.     

The effect of food deprivation prior to slaughter on performance, behaviour and meat quality

The effects of repeated food deprivation, prior to slaughter, on performance, feeding behaviour and meat quality of pigs was examined. Three experimental treatments were compared. In treatment 1 pigs had ad libitum access to feed up to the point of loading on the day of slaughter. Treatment 2 involved a 12-h fast prior to slaughter and treatment 3 involved a 20-h fast prior to slaughter. Pigs were slaughtered on a weight basis therefore each pen was emptied over a period of weeks. This meant some pigs experienced repeated food deprivation. The feeding pattern of pigs which were deprived of food for 12 h was very similar to that observed before feed restriction. Pigs which were deprived of food for 20 h spent significantly more time at the feeder post fasting. This was particularly marked during the first 2–3 h when access to feed was restored. Feed deprivation for 12 h prior to slaughter did not adversely affect performance, carcass weight, meat quality or welfare in the present study. Fasting for 20 h reduced carcass weight by 1 kg, which was not statistically significant but could result in financial losses related to carcass weight. The negative effects on meat quality, of repeated feed deprivation, resulted from slower growth rates rather than feed deprivation per se.     

Growth performance and fatty acid profiles of intramuscular and subcutaneous fat from Limousin and Charolais heifers fed extruded linseed

Forty-eight heifers, Limousin (LI) and Charolais (CH) breed, were used to evaluate the effect of a basal mixed diet with linseed supplementation (108g/kg DM) on performance and fatty acid (FA) composition of M. longissimus thoracis (MLT) and subcutaneous fat. The feed intake and weight gains were higher, and feed per gain ratio lower in CH heifers than in LI heifers. The muscle lipids and subcutaneous fat of LI heifers contained significantly more MUFA, PUFA, CLA, and less SFA than the lipids of CH heifers. The feeding of extruded linseed significantly increased the concentration of linolenic acid (C18:3n-3), CLA, and decreased PUFA n-6 to PUFA n-3 ratio in lipids extracted from both tissues. Linseed supplementation decreased SFA and increased PUFA in subcutaneous fat. In MLT lipids of linseed-fed heifers PUFA of the n-3 series were increased. It can be concluded that the growth performance of LI heifers was lower, but that their lipids contained more FA that are thought to be important for human health. The feeding of linseed at 108g/kg DM enhanced the nutritive value of beef in terms of FA profile. Breed differences were generally more important than effects of the diet. Dietary effects, however, were more pronounced in PUFA n-3 and arachidonic acid (C20:4n-6).     

The effect of stocking density during 4 hour transport to slaughter on behaviour, blood constituents and carcass bruising in Friesian steers

The aim of this work was to assess the response of Friesian steers to road transportation at low, medium and high (ca 200, 300 and 600 kg/m(2)) stocking densities in terms of physiology, behaviour and carcass bruising. Stocking density was determined by adjusting the number of animals per pen (3 runs) or by adjusting pen size (3 runs). Plasma cortisol and glucose increased (P < 0·001) with stocking density, as did plasma CK activity (P < 0·001) and carcass bruising (P < 0·01) both of which indicate muscle damage. At constant stocking density stress increased with pen location towards the tail of the truck, as reflected by a significant increase in plasma cortisol. Stocking density influenced standing orientation within the truck. At low stocking density animal movement was unrestricted and the preferred orientation was standing parallel to the direction of travel; there was a strong bias against diagonal orientations. Losses of balance were associated with specific driving events, notably braking and cornering. Minor losses of balance were observed at all stocking densities, but major losses of balance including animals going down underfoot were associated with high density. When an animal went down at high stocking density it did so involuntarily and was sometimes trapped down, destabilizing other members of the group in a domino effect. Exploratory, sexual and aggressive behaviours were inhibited at high stocking density, with the exception of mounting and pushing, which increased in frequency with stocking density. It was concluded that the high stocking density adversely affected animal welfare and lowered carcass quality when compared with the medium and low stocking densities.     

Effect of level, source, and time of feeding prior to slaughter of supplementary dietary magnesium on pork quality

A total of 192 pigs were utilized in a 2×3×3 factorial arrangement with an additional control treatment. The treatments were: (1) magnesium level (1.6 vs. 3.2 g of magnesium pig(-1) day(-1)); (2) magnesium source (sulfate vs. proprionate vs. proteinate); (3) feeding duration (5 vs. 2 vs. 1 day), and a control (no supplementary magnesium). Minolta L(?) values were lower (P?0.05), indicating darker muscle color, for pigs supplemented with 1.6 g magnesium pig(-1) day(-1) compared to the controls while pigs on the 3.2 g magnesium level were intermediate between these two treatments. Animals on the 1 day treatment had a higher (P?0.05) ultimate pH and lower (P?0.05) Minolta L(?) compared to those on the 2 days and control treatments, while 5 days pigs were intermediate and had lower L(?) values compared to the controls. The sulfate and proteinate treatments produced pork with the lower (P?0.05) Minolta L(?) values compared to the controls. Pigs fed the sulfate diet had a lower (P?0.05) drip loss compared to those on the control treatment. Results from this study suggest that the lowest level (1.6 g magnesium pig(-1) day(-1)) and the shortest time of supplementation (1 day) may be effective in improving pork color and water-holding capacity.     

Decontamination of cattle hides prior to slaughter using washes with and without antimicrobial agents

Two trials were conducted to determine the efficacy of cattle wash treatments in reducing pathogens on hides of cattle before slaughter. In trial I, live cattle (n = 120) were washed in an automated, commercial cattle wash system with one of four treatments (single water wash, double water wash, water wash with 0.5% L-lactic acid, or water wash with 50 ppm chlorine). Samples were collected at three locations (brisket, belly, and inside round) pre- and posttreatment to evaluate the effectiveness of treatments on the reduction of aerobic plate counts, coliforms, Escherichia coli and the incidence of Salmonella. For all three locations, bacterial numbers increased from 0.1 to 0.8 log CFU/cm2 posttreatment. In trial II, hide samples were inoculated in the laboratory with 6.0 log CFU/cm2 of rifampicin-resistant Salmonella serotype Typhimurium. Hide wash treatments included higher concentrations of chlorine (100, 200, and 400 ppm) and L-lactic acid (2, 4, and 6%), as well as other antimicrobial agents such as ethanol (70, 80, and 90%), acetic acid (2, 4, and 6%), and Oxy-Sept 333 (0.5, 2, and 4%). Spray wash treatments with ethanol and 4 to 6% concentrations of lactic acid had greater (P < 0.05) mean log reductions than 2% solutions of acetic or lactic acid, as well as 100, 200, and 400 ppm chlorine and the control water wash treatment. Spray wash treatments with Oxy-Sept 333 and 100, 200, or 400 ppm chlorine were not effective (P > 0.05) in reducing Salmonella Typhimurium compared to the (control) distilled water spray wash treatment. Several effective cattle hide interventions were identified in a controlled laboratory setting, but the high concentrations required for effectiveness would likely present problems from an animal welfare standpoint.     

Effects of long- or short-haul transportation of slaughter heifers and cattle liner microclimate on hide contamination with Escherichia coli O157

Effects of cattle transportation on hide contamination with Escherichia coli O157 have been variable, and the present study was designed to clarify relationships among duration of transport, microclimate, and environment within the trailer and contamination of hides with E. coli O157. Crossbred Angus heifers from a feedlot in southern Alberta were sorted into 10 replicate loads containing 45 animals (short haul, 621.5 ± 2.1 kg of body weight) or 46 animals (long haul, 576.0 ± 1.7 kg of body weight). Long-haul trips (n = 5) were made in July and August to slaughter plant A, whereas short-haul trips (n = 5) were made in October to slaughter plant B. The same trailer unit and driver were used for all loads. Data loggers were located in the ceiling of each compartment of the trailers to record ambient temperature and relative humidity. Each heifer was swabbed on the perineum on-farm prior to loading and immediately after stunning at the slaughter plant (an average 12-h transport for long haul and 1-h transport for short haul). Swabs were transported on ice before immunomagnetic separation for detection of E. coli O157. Transportation did not affect prevalence of hide contamination with E. coli O157, although 80% of long-haul swabs were positive on-farm compared with 26% of short-haul swabs, due to seasonality of shedding E. coli O157. Cattle transported in the nose compartment had fewer positive hide swabs (P < 0.05) than cattle in the deck or belly compartments during long-haul trips, even though the nose had a higher (P < 0.05) temperature-humidity index than the other compartments. Prevalence of hide contamination varied widely among loads even when the organism was at seasonally low levels. This suggests that the feedlot pen has a greater effect on hide contamination at the slaughter plant than transportation factors including temperature-humidity index, loading density, and duration of transport.     

Colour of fat,and colour,fatty acid composition and sensory characteristics of muscle from heifers offered alternative forages to grass silage in a finishing ration

The effect of type of silage offered to beef heifers during the finishing period on aspects of beef quality was determined. In two experiments, a diet based on grass silage (GS) was compared with a diet based on maize silage (MS) or whole-crop wheat silage (WCW). Compared to the GS-based diet, increasing the amount of MS linearly increased fat whiteness while the increase in fat whiteness due to WCW was dependent on the stage of crop maturity at harvesting. There was no effect of diet on muscle colour or on muscle pH measured at 48 h post-mortem, drip loss, taste panel traits after 14 days ageing or shear force values at 2, 7 or 14 days ageing. The alternative silages decreased the n − 3 polyunsaturated fatty acid proportion and increased the linoleic:linolenic acid ratio in intramuscular lipid. It is concluded that type of silage affects fat colour and fatty acid composition of muscle but not the other muscle characteristics examined.     

Effects of potassium lactate, sodium chloride, sodium tripolyphosphate, and sodium acetate on colour, colour stability, and oxidative properties of injection-enhanced beef rib steaks

This study determined the effects of potassium lactate (KL), sodium chloride, sodium tripolyphosphate, and sodium acetate on colour, colour stability, and oxidative properties of injection-enhanced beef rib steaks. Enhancement solutions (8.5% pump) contained combinations of KL (0% or 1.5%), sodium chloride (0.3% or 0.6%), sodium tripolyphosphate (0% or 0.3%), and sodium acetate (0% or 0.1%). Steaks were packaged in a high-oxygen modified atmosphere (80% O(2)/20% CO(2)). Steaks with KL or KL and sodium acetate were darker but more colour stable (P<0.05) than control steaks. Steaks had less glossy surfaces when they contained acetate (P<0.05) and KL (P<0.11). Increasing sodium chloride content resulted in darker, less colour-stable steaks (P<0.05). Removing phosphate had little impact on colour (P>0.05). Both KL and sodium acetate improved visual appearance of injection-enhanced beef rib steaks, whereas the greater salt level were detrimental.     

Influence of short- and long-term exposure to a hot environment on rumen passage rate and diet digestibility by Friesian heifers.

Effects of short- and long-term exposure to a hot environment on diet digestibility and rumen passage rate were studied in four, 10-mo-old Friesian heifers housed in a climatic chamber. The trial lasted 65 d. Twenty-five days were spent under thermal comfort (temperature-humidity index = 64), and 40 d were spent under hot conditions (temperature-humidity index = 84). Three digestibility and rumen passage rate trials were performed during the 65 d. Chromium oxide was used as an external marker. The first digestibility and rumen passage rate trial (trial 1) was performed under thermal comfort; trials 2 and 3 were performed under hot conditions. Exposure to the hot environment reduced dry matter intake and increased water intake and rectal temperature compared with those during the thermal comfort period. Digestibility coefficients for dry matter, organic matter, neutral detergent fiber, and acid detergent fiber were higher in trial 2 than in trials 1 and 3. No statistical differences were found between trials 1 and 3 for these variables. Rumen passage rate was more rapid in trial 1 than in trials 2 and 3. No difference was observed between trials 2 and 3. These results indicated that exposure to a hot environment can affect digestibility in a time-dependent fashion, suggesting an adaptation of the digestive tract to hot environments.     

Changes in colour characteristics and pigmentation of subcutaneous adipose tissue and M. longissimus dorsi of heifers fed grass, grass silage or concentrate-based diets

The objective of this experiment was to determine the effect of dietary composition and duration of feeding on subcutaneous (s.c.) adipose tissue and M. longissimus dorsi (LD) colour and pigment concentrations of heifers. Fifteen heifers were permanently housed and fed a concentrate diet (PH-CON). Fifty-four heifers were grazed on pasture (PAS) for 90d, housed and offered concentrates (PAS-CON), 200g grass silage (GS)/kg dry matter (DM) (PAS-GS20), 500g GS/kgDM (PAS-GS50) or zero-grazed grass (PAS-GRA). To facilitate assessment of the temporal pattern of tissue colour, 3 heifers/treatment were slaughtered at housing (following 7d adjustment to diets) and 28, 56, 91 and 120 days thereafter. Yellowness ('b' value) of s.c. adipose tissue and lightness ('L' value) and redness ('a' value) of LD were recorded 48h post-mortem. β-Carotene and lutein contents of s.c. adipose tissue and total LD haem pigments were determined. At housing, s.c. adipose tissue 'b' values of the PAS group (mean=13.47) were higher (P<0.01) than those of the PH-CON group (mean=10.35) but there was no difference in β-carotene or lutein concentrations. The change in s.c. adipose tissue 'b' for each diet following housing was best described by the following equations: PH-CON: y=-0.087 (SE 0.0347) X+0.0005 (SE 0.00029) X(2)+10.06 (SE 0.600), MSE 1.94, R(2) 0.57, P<0.01. PAS-CON: y=-0.102 (SE 0.0286) X+0.0006 (SE 0.00024) X(2)+13.32 (SE 0.598), MSE 2.30, R(2) 0.62, P<0.001. PAS-GS20: y=-0.106 (SE 0.0296) X+0.0008 (SE 0.00025) X(2)+13.10 (SE 0.618), MSE 2.46, R(2) 0.47, P<0.01. PAS-GS50: y=-0.077 (SE 0.0269) X+0.0006 (SE 0.00023) X(2)+13.29 (SE 0.552) MSE 1.95, R(2) 0.38, P<0.05. PAS-GRA: y=-0.018 (SE 0.0079) X+13.77 (SE 0.528), MSE 2.28, R(2) 0.24, P<0.05, where y='b' value, x=days post-housing (d96-d216) and MSE=mean square error. Treatment had a significant effect on s.c. adipose tissue β-carotene and lutein (both P<0.001) with PAS-GRA and PH-CON tending to have the highest and lowest concentrations, respectively. PH-CON heifers tended (P=0.058) to have lower LD haem pigments and lighter LD than other heifers. It is concluded that, while concentrate feeding led to the greatest decrease in s.c. adipose tissue yellowness relative to PAS-GRA, choice of dietary ingredients and duration of feeding will depend on the stringency of the colour criteria in particular markets.     

The effect of two handling and slaughter systems on skin damage, meat acidification and colour in pigs

In order to minimize the high proportion of carcass and meat quality defects recorded in commercially slaughtered pigs, the optimum handling, stunning and bleeding-out conditions must be implemented. In this study improvements in pig handling resulted in the elimination of electric goading within the raceways, which reduced the skin blemish score by 50%. Furthermore, the application of higher stunning voltage (200 V) and the immediate bleeding-out in the prone position improved the post-mortem acidification rate in the Longissimus thoracis (LT) and Semimembranosus (SM) muscles. This resulted in a sharp reduction of the PSE incidence in both muscles. A positive effect on muscle metabolism was also showed by the lower release of CPK into the bloodflow. These results show that, under commercial conditions, the design of slaughter handling systems and the slaughter procedures can have an effect on skin damage and on the quality of the pig meat.     

Use of infrared ocular thermography to assess physiological conditions of pigs prior to slaughter and predict pork quality variation

Infrared thermography (IRT) body temperature readings were taken in the ocular region of 258 pigs immediately before slaughter. Levels of lactate were measured in blood taken in the restrainer. Meat quality was assessed in the longissimus dorsi (LD), semimembranosus (SM), and adductor muscles. Ocular IRT (IROT) temperature was correlated with blood lactate levels (r = 0.20; P = 0.001), with pH taken 1 hour postmortem (pH1: r = − 0.18; P = 0.03) and drip loss (r = 0.20; P = 0.02) in the LD muscle, and with pH1 in the SM muscle (r = − 0.20; P = 0.02). Potentially, IROT may be a useful tool to assess the physiological conditions of pigs at slaughter and predict the variation of important meat quality traits. However, the magnitude of the correlations is rather low, so a further development of image capture technique and further studies under more variable preslaughter conditions ensuring a larger pork quality variation are needed.     

Lipid and protein oxidation in vitro, and antioxidant potential in meat from Charolais cows finished on pasture or mixed diet

In this work, the effect of finishing diet (pasture- or mixed-diet) on lipid and protein oxidation in beef homogenates was evaluated. Oxidation was chemically induced by ferrous iron and hydrogen peroxide. Lipid and protein oxidation were respectively measured by determining TBA reactive substances (TBA-RS) and protein carbonyl groups (DNPH coupling method). Evaluation of the antioxidant status of meat was also performed by measuring vitamin E concentration and antioxidant enzyme activities: superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase. Pasture-finishing mode of animals significantly protected lipids in meat from oxidation but diet mode did not affect protein oxidation. Concentration of vitamin E was higher in meat from pasture-fed animals. Different diets had opposite effects on SOD and GPx activities, pasture-finishing mode of animals increasing SOD activity but decreasing GPx activity. No significant effect of diet was noted on catalase activity.