Relationships of behavioral and physiological symptoms of preslaughter stress to beef longissimus muscle tenderness.
ABSTRACT Relationships between behavioral and physiological symptoms of preslaughter stress and LM Warner-Bratzler shear force (WBSF) were investigated using Bos taurus steers (n = 79) and heifers (n = 77). Measurements of heart rate, respiration rate, rectal temperature, and concentrations of serum cortisol and plasma epinephrine were used as indicators of stress associated with physical handling and chute restraint, whereas concentrations of cortisol, glucose, lactate, and creatine kinase in blood samples obtained at exsanguination were measured to reflect physiological reactions of animals to transportation stress. Increased plasma epinephrine concentration, indicative of acute handling stress, was associated with elevated heart rate (r = 0.42, P < 0.001) and rectal temperature (r = 0.34, P < 0.001) during restraint, increased plasma lactate (r = 0.22, P = 0.006) and serum creatine kinase (r = 0.28, P < 0.001) concentrations at slaughter, and greater LM WBSF (r = 0.22, P = 0.006). Plasma lactate concentration at slaughter, which reflected an adrenergic stress response to transportation, was associated with lesser final LM pH (r = -0.30, P < 0.001) and greater LM WBSF (r = 0.26, P = 0.002). Categorical analyses of chute and posttransportation behavior scores (calm vs. restless vs. nervous) showed that cattle exhibiting adverse behavioral reactions to handling and chute restraint had increased (P < 0.05) values for plasma epinephrine concentration, heart rate, and rectal temperature during chute restraint, elevated (P < 0.05) plasma lactate concentration at slaughter, and increased (P < 0.05) LM WBSF. In addition, cattle showing behavioral symptoms of stress after transportation had greater (P < 0.05) plasma glucose and lactate concentrations at slaughter and produced LM steaks that were 0.34 kg tougher (P < 0.05) when compared with calm cattle. No carcasses were identified as dark cutters, and LM pH did not differ (P > 0.05) among behavior categories. Grouping cattle according to differences in plasma lactate concentration categorized them according to mean differences in LM WBSF. Moreover, steaks from cattle with the greatest plasma lactate concentrations at slaughter (91st to 100th percentile) had a delayed response to aging that persisted until 14 d postmortem. Stress-induced differences in LM tenderness observed in this study were independent of differences in muscle pH.
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ABSTRACT: Young adults in developed countries are distanced from agriculture and the meat industry needs to do a better job of communicating with them. A major welfare concern is slaughter without stunning. Other concerns, such as poor stunning or high levels of bruising, can be easily corrected by management who is committed to maintaining high standards. Another concern is biological system overload, occurring when animals are bred for more productivity. Researchers and industry need to determine optimum production levels instead of maximums. Retailers are major drivers of animal welfare standards enforcement and they respond to pressure from both activists and consumers.Meat Science 01/2014; · 2.75 Impact Factor
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ABSTRACT: Physiological and behavioural reactions of cattle to handling procedures in a commercial abattoir (electrical prodding actions and duration of the animals' stay in the stunning box) were evaluated and set in relation to sex, breed type, and carcass weight. A total of 192 cattle comprised of 45 bulls, 61 steers, and 86 heifers from different breed types (30 dairy breed, 70 beef breed, and 92 crossbreds) were observed from lairage to slaughter during one day. The frequency of electrical proddings and the waiting time in the stunning box were recorded for each individual. As a measure of a behavioural stress response, the number of vocalising animals was recorded. Exsanguination blood serum samples were analysed for cortisol, glucose, and lactate concentrations. Forty-nine animals received no electrical prods; 117 animals were prodded one to three times, and 24 animals received between 4 and 9 prods. Thirteen percent of all animals were recorded as vocalisers. There was a trend (P=0.07) that heifers vocalised more than bulls and steers. Mean levels per ml of blood were 77.2 ng cortisol (SE=68.8), 5.7 μmol glucose (SE=1.3), and 6.7 μmol lactate (SE=3.3). Cortisol concentrations were lower in bulls than in steers and in heifers (P<0.01), and concentrations above 90 ng/ml were measured in 21.3% of the steers and 27.8% of the heifers, but not in the bulls. Lactate and glucose concentrations were not influenced by sex. Breed type had no influence on any of the stress-indicating traits. Prodding categories were not related with concentrations of the blood variables and the number of vocalising animals. A longer stay in the stunning box led to increased cortisol concentrations (P<0.05), but had no influence on lactate and glucose concentrations or on the number of vocalising animals. In conclusion, stress levels were relatively high in the present case, but it was not possible to relate the stress indicators unequivocally to the potential factors of influence investigated.Livestock Science 06/2014; · 1.25 Impact Factor
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ABSTRACT: This study evaluated the effect of animal temperament measured using flight speed (FS) on plasma lactate, muscle glycogen and lactate concentrations at slaughter plus ultimate pH in 648 lot finished cattle of mixed breed and sex. Muscle samples were collected at slaughter from the m. semimembranosus, m. semitendinosus and m. longissimus thoracis (LT) for analysis of glycogen and lactate concentration. Blood was collected after exsanguination and analysed for plasma lactate concentration and ultimate pH of the LT was measured. FS had no effect on muscle glycogen concentration in any muscle or ultimate pH of the LT (P>0.05). As FS increased from 1 to 5m/s, plasma and muscle lactate concentration increased by 54% and 11.4% (P<0.01). The mechanisms through which temperament contributes to variation in glycogen metabolism remain unclear. The risk of dark cutting was not impacted by temperament, indicating that other production and genetic factors have a greater impact on the incidence of dark cutting.Meat Science 08/2014; 98(4):815-821. · 2.75 Impact Factor