Effects of farm management practices and transport duration on stress response and meat quality traits of suckling goat kids

Studies aimed to assess up to what extent farming and transport previous to slaughtering might affect physiology and meat quality in young goat kids are needed, with the ultimate purpose of promoting practices that minimize stress in these animals. In this regard the effects of on-farm management and transport duration on some physiological responses and meat quality parameters in goat kids were assessed. Two farms representing ‘high’ and ‘low’ welfare-friendly management practices were selected. In total, 32 suckling kids were withdrawn from each farm, transported by road for 2 or 6 h, and then slaughtered. Blood samples were collected both on-farm and in the slaughterhouse, and biochemistry, cell counts and haematocrit were determined. After slaughtering, carcass quality parameters were measured. Longissimus dorsi muscle was dissected and pH, colour parameters, water holding capacity and shear force were measured throughout 8-day ageing period. Results indicate that, regardless its duration, transport caused significant effects on some blood parameters suggesting stress in live animals, like glucose, cortisol or creatine kinase. Despite the marked stress status in animals, this condition was not decisively reflected on L. dorsi quality parameters, but some effects were observed regarding fat cover in carcasses and colour parameters. The results suggest that postmortem changes throughout ageing were more decisive in terms of meat quality than stressful management either on-farm or during transport.     

Black soldier fly defatted meal as a dietary protein source for broiler chickens: effects on carcass traits,breast meat quality and safety

Finding insect meals as alternative sources of poultry feedstuffs is a recent research topic; therefore, the present study aimed to evaluate the effects of defatted black soldier fly (Hermetia illucens L., HI) larvae meal in broiler chicken diets on the carcass characteristics and meat quality parameters, proximate composition, fatty acid profile and the heavy metal content of the breast meat. Four dietary treatments were designed: a control diet (HI0) and three experimental diets (HI5, HI10 and HI15), corresponding to 50, 100 and 150 g/kg HI inclusion levels, respectively. The inclusion of 50, 100 and 150 g HI meal per kg feed supply 16.56%, 33.01% and 49.63% of required crude protein. The broilers were slaughtered at day 35, the carcasses were weighed and the breast muscles were excised from 16 birds per each feeding group (two birds per replicate pens) and used for meat quality evaluation. Linear and quadratic responses were observed, for increasing HI meal levels, in the live and carcass weights (maximum for HI10). As far as the colour of the breast meat is concerned, redness (a*) showed a linear response, while yellowness (b*) linearly decreased with increasing HI meal levels (minimum for HI15). As the HI larvae meal increased in the diets, the moisture content linearly decreased and the protein content increased. The total saturated fatty acid and total monounsaturated fatty acid proportions rose to the detriment of the polyunsaturated fatty acid fraction. The HI larvae meal, used in the current study, represents a valuable protein source for broiler chickens when included by up to 100 g/kg in their diets, as an improved slaughtering performance was observed without any detrimental effects on meat quality parameters or heavy metal residues in the meat.     

The effect of polyphenols and vitamin E on the antioxidant status and meat quality of broiler chickens exposed to high temperature

The aim of this study was to determine the effect of a polyphenol product (PP) (Proviox) and vitamin E on the antioxidant status and meat quality of broiler chickens exposed to high temperature. The experimental materials comprised 120 ROSS 308 broilers (6 treatments, 10 replications, 2 birds per replication). Dietary supplementation with vitamin E and PP was applied in the following experimental design: group I (negative control) – without supplementation; group II (positive control) – without supplementation; group III – supplementation with 100 mg vitamin E/kg; group IV – 200 mg vitamin E/kg; group V – 100 mg vitamin E/kg and 100 mg PP/kg; group VI – 200 mg PP/kg. In groups II–VI, broiler chickens aged 21–35 d were exposed to increased temperature (34°C for 10 h daily). In chickens exposed to high temperature, dietary supplementation with antioxidants, mostly PP, improved growth performance parameters, including body weight, body weight gain and feed intake until 28 d of age. Vitamin E added to broiler chicken diets at 200 mg/kg and vitamin E combined with PP was most effective in improving the total antioxidant status of birds, enhancing blood antioxidant enzyme activities and increasing vitamin E concentrations in the liver and breast muscles. Broilers fed diets supplemented with 200 mg/kg of vitamin E alone and vitamin E in combination with PP were characterised by a higher percentage content of breast muscles in the carcass. Dietary supplementation with antioxidants improved the water-holding capacity of meat, reduced natural drip loss and increased the crude ash content of meat. The breast muscles of chickens fed diets supplemented with PP had a lower contribution of yellowness. The breast muscles of chickens receiving diets with 100 mg vitamin E/kg(group III) and diets supplemented with PP (groups V and VI) were characterised by the highest concentrations of polyunsaturated fatty acids. The PP can be a valuable component of diets for broiler chickens exposed to high temperature.     

Supplemental zinc and vitamin A can alleviate negative effects of heat stress in broiler chickens

This experiment was conducted to evaluate the effects of zinc (ZnSO₄H₂O) and vitamin A (retinol) supplementation on performance, carcass characteristics, and serum concentrations of glucose, cholesterol, total protein, and malondialdehyde (MDA) as an indicator of lipid peroxidation in broiler chickens (Ross) reared at a high temperature (34°C). One hundred twenty 10-d-old male broilers were randomly assigned to 4 treatment groups, 3 replicates of 10 birds each. The birds were fed either a basal diet or the basal diet supplemented with either 30 mg Zn/kg diet, 4.5 mg (15,000 IU) retinol/kg diet, or 30 mg Zn+4.5 mg retinol/kg diet. Supplemental zinc and vitamin A significantly increased live weight gain and improved feed efficiency (p<0.05). However, a combination of zinc and vitamin A, rather than each separately, provided a greater performance. Hot and chilled carcass weights and yields and the weights of internal organs with the exception of abdominal fat were greater for each supplement (p<0.05) compared to the control group. Abdominal fat decreased (p<0.05) upon dietary zinc and vitamin A supplementation. Supplemental treatments resulted in an increased total serum protein but decreased glucose, cholesterol, and MDA concentrations. The results of the study show that, separtely or as a combination, zinc and vitamin A supplementation resulted in an improved live weight gain, feed efficiency, and carcass traits, as well as a decrease in serum MDA concentrations. The results of the present study also suggest that zinc and vitamin A have similar effects and that a combination of zinc and vitamin A may offer a potential protective management practice in preventing heat-stress-related depression in performance of broiler chickens.     

Physiological changes associated with acclimation of broiler chickens to constant temperatures

An experiment was conducted to determine whether the physiological parameters that respond to temperature would equate to a common level after birds are acclimated to differing temperatures and then reared as one group at a common temperature. Results show that of the parameters measured, the heart/body weight ratio is the most sensitive to temperature changes. When birds were reared in differing constant temperatures from 1 to 28 days of age and then subjected to a common environment, by 56 days of age, the heart/body weight ratio had equated. However, the liver- and adrenal/body weight ratio and hematocrit did not completely equate for the temperature extremes by 56 days of age. Parameters measured but unaffected by temperature treatment were spleen- and bursa/body weight ratios.     

Circadian rhythms of biomarkers of oxidative stress and their characteristics in broiler chickens reared under natural light/dark cycle

For the purpose of studying circadian rhythms of biomarkers of oxidative stress in broiler chickens maintained under natural photoperiod, we collected blood from the wing veins of 10 matured broiler chickens every three hours for a period of 24 h. The blood samples were analyzed for superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA). The fitting in of single cosinor procedure showed that CAT and MDA exhibited clear circadian rhythms, while SOD did not. The amplitude of daily rhythms for the parameters was small, while the acrophases were all restricted to the light phase of the light:dark cycle. In conclusion, to our knowledge, this is the first time investigation of the circadian rhythms of antioxidants in broilers chickens, reared under natural photoperiod in the tropics. The result may be exploited for a more precise targeting of reactive oxygen species, thereby offering better protection for the cells to combat oxidative stress.     

Changes in muscle cell cation regulation and meat quality traits are associated with genetic selection for high body weight and meat yield in broiler chickens

Between-breed genetic variation for muscle and meat quality traits was determined at eight weeks of age in 34 lines of purebred commercial broiler and layer lines and traditional breeds (categories) of chickens. Between-breed genetic variation for plasma ion concentrations and element concentration in muscle dry matter and ash were determined. Plasma from broilers had higher concentrations of Na⁺, K⁺, Mg⁺⁺, total and free Ca⁺⁺ and lower free:total Ca⁺⁺ than plasma from layer and traditional lines. Muscle from broilers contained more Na and higher concentrations of K, Mg and Ca per mg of ash but not of dry matter compared with layer and traditional lines. In comparison with layer and traditional lines, broiler genotypes were over three times heavier, their plasma creatine kinase activity (CK), a marker of muscle tissue damage, was higher, their breast muscle colour was lighter (L*) and less red (a*) and yellow (b*) in appearance, the initial and final pH of their muscles were lower, the pH change was higher and their breast muscle was more tender. Thus, genetic selection for broiler traits has markedly altered cation regulation in muscle cells and may be associated with changes in muscle cell function and the development of pathology and meat quality problems.     

Effects of inclusion level and source of dietary sodium on performance and meat characteristics of broiler chickens

The effect of different concentrations of dietary Na from three Na salts (NaCl, NaHCO3 and Na2SO4) was assessed in two experiments carried out on broiler chickens aged from 1 to 35 days. In Exp. 1, diets were supplemented with 0.15, 0.20 and 0.25% Na, which increased the average Na content of the diets to 0.19, 0.24 and 0.30% respectively. In Exp. 2, the amounts of selected Na salts (NaCI and Na2SO4) were reduced and the estimated Na contents of experimental diets amounted to 0.10, 0.13, 0.15 and 0.19%. In view of the risk factors for the development of foot pad dermatitis, our aim was to find an optimum source of Na and to keep dietary Na intake at the minimum level sufficient to support normal growth and acceptable slaughter quality. The present results suggest that the amount of Na required for the undisturbed growth of broilers and adequate feed conversion is not less than 0.15% of additional Na in the starter period (1-14 d), and not less than 0.11% in the grower period (until day 35). Higher dietary Na levels did not lead to further production advantages, and were found to increase the moisture content of droppings. Dry matter concentration of excreta was also affected by Na source. In comparison with NaHCO3, Na2SO4 seemed to be a better alternative for NaCl. Na2SO4 also tended to surpass NaHCO3 as a dietary alternative for NaCl in terms of feed utilisation during the starter period. The applied additional Na levels (0.25 and 0.15%) and Na sources had no effect on the sensory profile and composition of breast meat.     

Effect of indomethacin on hyperthermia induced by heat stress in broiler chickens

 An investigation was carried out to verify whether the heat stress hyperthermia response of broilers is prostaglandin-dependent. Male broiler chickens of the Hubbard-Petterson strain, aged 35–49 days, were used. Chickens were injected with indomethacin (1 mg/kg intraperitoneally ) 15 min before or 2 h after heat exposure (at 35°C for 4 h), and rectal temperature was measured before injection and up to 4 h thereafter. Birds were separated into two groups with and without access to water during heat stress. The increase in rectal temperature was lower (P<0.05) in birds with access to drinking water during heat exposure. All birds injected with indomethacin exhibited an increase in rectal temperature, irrespective of whether indomethacin was administered before or in the course of the rise in temperature. The results revealed that the increase in rectal temperature during heat exposure is not prostaglandin-dependent, and that the use of cyclooxigenase inhibitors is not recommended to attenuate heat stress hyperthermia in broiler chickens. Received: 15 December 1997 / Revised: 29 June 1998 / Accepted: 31 July 1998     

Effects of inclusion level and source of dietary sodium on performance and meat characteristics of broiler chickens

The effect of different concentrations of dietary Na from three Na salts (NaCl, NaHCO₃ and Na₂SO₄) was assessed in two experiments carried out on broiler chickens aged from 1 to 35 days. In Exp. 1, diets were supplemented with 0.15, 0.20 and 0.25% Na, which increased the average Na content of the diets to 0.19, 0.24 and 0.30% respectively. In Exp. 2, the amounts of selected Na salts (NaCl and Na₂SO₄) were reduced and the estimated Na contents of experimental diets amounted to 0.10, 0.13, 0.15 and 0.19%. In view of the risk factors for the development of foot pad dermatitis, our aim was to find an optimum source of Na and to keep dietary Na intake at the minimum level sufficient to support normal growth and acceptable slaughter quality. The present results suggest that the amount of Na required for the undisturbed growth of broilers and adequate feed conversion is not less than 0.15% of additional Na in the starter period (1–14 d), and not less than 0.11% in the grower period (until day 35). Higher dietary Na levels did not lead to further production advantages, and were found to increase the moisture content of droppings. Dry matter concentration of excreta was also affected by Na source. In comparison with NaHCO₃, Na₂SO₄ seemed to be a better alternative for NaCl. Na₂SO₄ also tended to surpass NaHCO₃ as a dietary alternative for NaCl in terms of feed utilisation during the starter period. The applied additional Na levels (0.25 and 0.15%) and Na sources had no effect on the sensory profile and composition of breast meat.     

Cyclopiazonic acid production by Aspergillus flavus and its effects on broiler chickens

Cyclopiazonic acid (CPA) was purified from cultures of Aspergillus flavus, and ca. 14 g of the toxin was collected for use in feeding studies. Chicken rations were artificially contaminated with purified CPA at concentrations of 10, 50, and 100 ppm (microgram/g) and fed ad libitum to eight groups of chickens for 7 weeks. Chickens receiving feed with 100 ppm of CPA had high mortality, decreased weight gain, and poor feed conversion when compared with birds receiving other doses. Postmortem examination showed that chickens fed the two greatest doses of CPA had proventricular lesions characterized by mucosal erosion and hyperemia (100 ppm) and by thick mucosa and dilated proventricular lumens (50 ppm). Birds given 100 ppm of CPA in feed also had numerous yellow foci in their livers and spleens. Microscopic examination of tissues of birds that received 100 ppm of CPA revealed ulcerative proventriculitis, mucosal necrosis in the gizzard, and hepatic and splenic necrosis and inflammation. Birds given 50 ppm of CPA had hyperplasia of the proventricular mucosal epithelium. Birds given 10 ppm of CPA and control birds had no significant treatment-related lesions.     

Physiological response and carcass and meat quality of suckling lambs in relation to transport time and stocking density during transport by road

To evaluate the effect of stocking density and transport time on physiological responses and meat quality, 72 male suckling lambs were transported by road to the slaughterhouse at three different stocking densities (0.12, 0.20 or 0.25 m2/lamb) and two transport times (5 h or 30 min). Blood samples were collected pre-transport at the farm and after unloading in the slaughterhouse to measure levels of cortisol, creatine kinase (CK) and lactate dehydrogenase (LDH). After slaughter, the weights of the hot carcass, liver and spleen were recorded and pH in Musculus longisimus thoracis et lumborum (L), Musculus semitendinosus (ST) and Musculus psoas major (PM) were determined. Colour, water-holding capacity (WHC), texture and thiobarbituric acid-reactive substances (TBARS) values were measured in samples of L, at 24 h post mortem and after 5 days of ageing. Cortisol and LDH were higher in suckling lambs transported for 30 min than those transported for 5 h. Stocking density did not affect blood parameters studied. Transport time significantly affected some carcass quality parameters, but stocking density had no significant effect. Suckling lambs transported for 5 h had lower liver weights and dressing percentages than those transported for 30 min. Transport time influenced pH values, with lambs subjected to the longer journey showing the lowest pH at 0 h in the three muscles studied, with the lowest final pH in L and PM. The PM lambs transported at high density (0.12 m2/lamb) had the lowest pH at 24 h. Transport time and stocking density did not greatly affect colour and texture parameters. The meat from lambs transported for 30 min had higher WHC than meat from lambs transported for 5 h. Animals transported for longer journeys showed higher lipid oxidation after 5 days of ageing than those transported for 30 min. Loading and initial transport caused significant stress response in suckling lambs, that stress response was reduced over the time course of the journey.     

Impaired development of broiler chickens by stress mimicked by corticosterone exposure

The effects of corticosterone (CORT) administration on the development of muscular tissues of broiler chickens (Gallus gallus domesticus) fed with diets differing in lipid content were investigated. The experimental chickens were given one of two experimental diets: high lipid diet (9.9% crude fat) or control diet, from 21 d of age. At 28 d of age, half of the chickens in each dietary treatment were exposed to CORT treatment, supplemented with 30 mg CORT/kg diet for 12 days, while the other half continued to consume the former diet. The zootechnical parameters were recorded at 21, 28, 35 and 39 d, and a blood sample was obtained from 8 birds of each group, respectively. The growth performance of broiler chickens was significantly depressed by CORT administration, but not by dietary treatment. Corticosterone treatment resulted in enhanced energy expenditure. The results indicate that the development of breast muscle was more susceptible to stress mimicked by CORT administration. The results suggest that corticosterone administration enhanced hepatic fatty acid synthesis and resulted in the redistribution of energy to abdominal store from peripheral tissues. Diet rich in lipid content was favorable to the central fat deposit in stressed broiler chickens.     

Accelerated tissue aging and increased oxidative stress in broiler chickens fed allopurinol

Uric acid has been hypothesized as being one of the more important antioxidants in limiting the accumulation of glycosylated endproducts in birds. Study 1 was designed to quantitatively manipulate the plasma concentrations of uric acid using hemin and allopurinol while study 2 determined their effects on skin pentosidine, the shear force value of Pectoralismajor muscle, plasma glucose, body weight and chemiluminescence monitored oxidative stress in broiler chickens. Hemin was hypothesized to raise uric acid concentrations thereby lowering oxidative stress whereas allopurinol was hypothesized to lower uric acid concentrations and raise measures of oxidative stress. In study 1 feeding allopurinol (10 mg/kg body weight) to 8-week-old broiler chicks (n=50) for 10 days decreased plasma uric acid by 57%. However, hemin (10 mg/kg body weight) increased uric acid concentrations 20%. In study 2, 12-week-old broiler chicks (n=90) were randomly assigned to either an ad libitum (AL) diet or a diet restricted (DR) group. Each group was further divided into three treatments (control, allopurinol or hemin fed). Unexpectedly, hemin did not significantly effect uric acid concentrations but increased (P<0.05) measures of chemiluminescence dependent oxidative stress in both the DR and AL birds probably due to the ability of iron to generate oxygen radicals. Allopurinol lowered concentrations of uric acid and increased (P<0.05) the oxidative stress in the AL birds at week 22, reduced (P<0.05) body weight in both the AL and DR fed birds at 16 and 22 weeks of age, and markedly increased (P<0.001) shear force values of the pectoralismajor muscle. Skin pentosidine levels increased (P<0.05) in AL birds fed allopurinol or hemin fed birds, but not in the diet restricted birds at 22 weeks. The significance of these studies is that concentrations of plasma uric acid can be related to measures of oxidative stress, which can be linked to tissue aging.     

Cyclopiazonic acid production by Aspergillus flavus and its effects on broiler chickens.

Cyclopiazonic acid (CPA) was purified from cultures of Aspergillus flavus, and ca. 14 g of the toxin was collected for use in feeding studies. Chicken rations were artificially contaminated with purified CPA at concentrations of 10, 50, and 100 ppm (microgram/g) and fed ad libitum to eight groups of chickens for 7 weeks. Chickens receiving feed with 100 ppm of CPA had high mortality, decreased weight gain, and poor feed conversion when compared with birds receiving other doses. Postmortem examination showed that chickens fed the two greatest doses of CPA had proventricular lesions characterized by mucosal erosion and hyperemia (100 ppm) and by thick mucosa and dilated proventricular lumens (50 ppm). Birds given 100 ppm of CPA in feed also had numerous yellow foci in their livers and spleens. Microscopic examination of tissues of birds that received 100 ppm of CPA revealed ulcerative proventriculitis, mucosal necrosis in the gizzard, and hepatic and splenic necrosis and inflammation. Birds given 50 ppm of CPA had hyperplasia of the proventricular mucosal epithelium. Birds given 10 ppm of CPA and control birds had no significant treatment-related lesions.     

The effect of Cu,Zn and Fe chelates on the antioxidative status of thigh meat of broiler chickens

The studies aimed to verify the effect of Cu, Zn and Fe glycine chelate on the antioxidative status in the thigh meat of broiler chickens. The study assumption was that due to the antioxidative or prooxidative effect of Cu, Zn and Fe, these elements supplemented to chickens in an easily assimilable form would modify the antioxidative status of meat and those having a prooxidative effect could deteriorate the quality of meat. The experiment involved three hundred and fifty Ross 308 chickens divided into seven equipotent experimental groups. Over 42 days of the experiment, the chickens were administered Cu, Zn and Fe glycine chelates in an amount corresponding to 50% of the requirement (experimental factor I) or 25% of the requirement (experimental factor II). The level of oxidative stress indicators such as superoxide dismutase, catalase, glutathione, glutathione peroxidase and malondialdehyde was determined in the muscles and blood. The groups receiving Zn or Cu chelate showed statistically confirmed higher activity of superoxide dismutase, catalase, and a higher level of glutathione in comparison to the group receiving Fe chelate. In order to increase the antioxidative stability of thigh meat, it is sufficient that broiler chickens receive Zn or Cu in the form of glycine chelate in an amount covering 25% of their requirement of such minerals. On the other hand, the use of Fe glycine chelates decreased antioxidative stability due to an increase in the level of malondialdehyde, so it should be considered whether the administration of pro-oxidative Fe chelate to broilers is advisable.     

Carcass and meat quality traits of chickens fed diets concurrently supplemented with vitamins C and E under constant heat stress

The objective of this study was to determine if a diet supplemented simultaneously with vitamins C and E would alleviate the negative effects of heat stress, applied between 28 and 42 days of age, on performance, carcass and meat quality traits of broiler chickens. A total of 384 male broiler chickens were assigned to a completely randomized design, with a 2×3 factorial arrangement (diet with or without vitamin supplementation and two ambient temperatures plus a pair-feeding group) and 16 replicates. Chickens were kept in thermoneutral conditions up to 28 days of age. They were then housed in groups of four per cage, in three environmentally controlled chambers: two thermoneutral (22.5 and 22.6°C) and one for heat stress (32°C). Half the chickens were fed a diet supplemented with vitamins C (257 to 288 mg/kg) and E (93 to 109 mg/kg). In the thermoneutral chambers, half of the chickens were pair-fed to heat stressed chickens, receiving each day the average feed intake recorded in the heat stress chamber in the previous day. Meat physical quality analyses were performed on the pectoralis major muscle. No ambient temperature×diet supplementation interaction effects were detected on performance, carcass, or meat quality traits. The supplemented diet resulted in lower growth performance, attributed either to a carry-over effect of the lower initial BW, or to a possible catabolic effect of vitamins C and E when supplemented simultaneously at high levels. Heat stress reduced slaughter and carcass weights, average daily gain and feed intake, and increased feed conversion. Growth performance of pair-fed chickens was similar to that of heat stressed chickens. Exposure to heat stress increased carcass and abdominal fat percentages, but reduced breast, liver and heart percentages. Pair-fed chickens showed the lowest fat percentage and their breast percentage was similar to controls. Heat stress increased meat pH and negatively affected meat color and cooking loss. In pair-fed chickens, meat color was similar to the heat stressed group. Shear force was not influenced by heat stress, but pair-fed chickens showed the tenderest meat. In conclusion, reduction in growth performance and negative changes in meat color in heat stressed chickens were attributed to depression in feed intake, whereas negative changes in body composition, higher meat pH and cooking loss were credited to high ambient temperature per se. Diet supplementation with vitamins C and E as antioxidants did not mitigate any of these negative effects.     

Impact of transport crate reuse and of catching and processing on Campylobacter and Salmonella contamination of broiler chickens

The influence of transport, catching, and processing on contamination of broiler chickens with Salmonella and Campylobacter was investigated. Transport crates were reused with high frequency and were often still contaminated with Salmonella and Campylobacter when they arrived at the farm despite the fact that they were washed at the factory, and thus they were a potential route of infection. These organisms contaminated the feathers of previously Campylobacter- and Salmonella-negative birds going to the processing plant and were isolated from processed carcasses, albeit at a low frequency. The Campylobacter types which were the predominant organisms on the live birds when they arrived at the processing plant were not necessarily the types that were most frequently isolated from processed carcasses. This finding may reflect cross-contamination that occurred during processing or differences in the tolerance of the strains to the hostile environments that the bacteria experienced. The process of catching and putting the birds in crates significantly increased the chance of contamination with Campylobacter (P < 0.001).