Effect of β-glucosidase on the meat quality and digestibility in broilers

This study investigated the effects of supplementary β-glucosidase on the carcass composition, meat quality, weight of digestive organ and apparent digestibility in male broilers. Two hundred and forty male, 1-day avine broiler chicks were randomly allocated into four treatment groups and fed with corn-soya bean meal supplemented with 0 (control), 0.6, 1.2 and 1.8 U/g of β-glucosidase respectively. The results showed that there were no significant differences (p > 0.05) among groups in carcass composition (percentages of eviscerated yield, half-eviscerated yield, muscle yield of breast and leg). However, adding 0.6 U/g β-glucosidase to the diet not only altered the meat quality by decreasing the drip loss ratio (p < 0.05) and relative lightness (L*) value (p < 0.01), increasing relative redness (a*) value (p < 0.01), but also significantly decreased the pancreas to body weight ratio (p < 0.05), however, with little effect on liver, proventriculus and gizzard to body weight ratio (p > 0.05). The length and width of duodenum villus were not affected by the addition of β-glucosidase, but the coefficients of total tract apparent digestibility of protein and fat increased by 9.02% (p < 0.05) and 7.40% (p < 0.01) respectively; the parameters of ash were not affected by β-glucosidase addition (p < 0.05). This study provided valuable information for evaluation of the effect of supplementary β-glucosidase on the meat quality and digestibility of broilers.     

Ileal amino acid digestibility assay for the growing meat chicken—effect of the imposition of a fasting period and the nature of the test diet

1. The objective of this study was to investigate the effects of cold‐pelleting, the length of the fasting period before feeding of the test diet and the nature of die test diet on apparent ileal nitrogen (N) digestibility in the broiler chicken.

2. Four‐week‐old broiler chickens were given a pelleted or non‐pelleted maize/soyabean meal (basal) diet. The birds were starved for 24 h, given a single test meal (25 g) by intubation and killed 4 h after the start of feeding by administration of a barbiturate, to allow sampling of ileal digesta (terminal 15 cm). Cold‐pelleting did not affect apparent ileal N digestibility.

3. Four‐week‐old broiler chickens were fasted for 12 or 24 h and then received a test meal (1 h free access) of either a pelleted soyabean meal or a pelleted meat‐and‐bone meal diet or were continuously fed on one of the two diets. The imposition of a fast did not affect apparent ileal N digestibility. However, a 24 h fasting procedure was preferred, as the between animal variation for apparent ileal N digestibility was lower than for the 12 h fast or for continuous feeding.

4. Four‐week‐old broiler chickens were given either semi‐synthetic starch‐based diets containing maize, wheat bran, meat‐and‐bone meal or fish meal as the sole sources of protein or each of these diets in combination with the basal diet (50:50 on a dry matter basis). With the exception of the maize diet, the apparent ileal N digestibility values calculated by correcting for the digestibility of the basal dietary component were significantly lower than when digestibility was determined directly using a diet in which the respective proteins were the sole protein source. This implies that interactions between the dietary ingredients influence estimates of apparent ileal N digestibility.     

Influence of diet on the intestinal microflora and meat flavour of intensively‐reared broiler chickens

1. An attempt has been made to modify the composition of the gut flora of broiler chickens by dietary means in order to determine any concurrent changes in meat flavour.

2. Birds given a diet containing an increasing proportion of whole wheat supplemented with fresh green vegetable matter (special diet) were compared with conventionally‐fed controls. At 12 weeks of age those receiving the special diet had 10 to 100‐fold higher counts of Escherichia colt and faecal streptococci in the duodenum and lower small intestine and showed differences in the intestinal incidence of species and biotypes of lactobacilli.

3. Evaluation of cooked breast‐meat samples by a trained sensory panel showed a significant difference in flavour (P < 0.01) between conventional and special‐diet birds which varied from perceptually very slight to slight. The main terms used in distinguishing special‐diet birds from conventional controls included ‘richer’, ‘meatier’ and ‘sweeter’.

4. Storage of plucked, uneviscerated birds at 4 °C for 8 d maintained the flavour difference between the dietary groups but the effect of storage on flavour was greater in both groups of birds than the influence of diet alone. The likely influence on flavour of autolytic changes occurring in the muscle during storage of the birds is discussed.     

Vaccination of pigs with the S48 strain of Toxoplasma gondii – safer meat for human consumption

As clinical toxoplasmosis is not considered a problem in pigs, the main reason to implement a control strategy against Toxoplasma gondii (T. gondii) in this species is to reduce the establishment of T. gondii tissue cysts in pork, consequently reducing the risk of the parasite entering the human food chain. Consumption of T. gondii tissue cysts from raw or undercooked meat is one of the main sources of human infection, with infected pork being considered a high risk. This study incorporates a mouse bioassay with molecular detection of T. gondii DNA to study the effectiveness of vaccination (incomplete S48 strain) in its ability to reduce tissue cyst burden in pigs, following oocyst (M4 strain) challenge. Results from the mouse bioassay show that 100% of mice which had received porcine tissues from vaccinated and challenged pigs survived compared with 51.1% of mice which received tissues from non-vaccinated and challenged pigs. The presence (or absence) of T. gondii DNA from individual mouse brains also confirmed these results. This indicates a reduction in viable T. gondii tissue cysts within tissues from pigs which have been previously vaccinated with the S48 strain. In addition, the study demonstrated that the main predilection sites for the parasite were found to be brain and highly vascular muscles (such as tongue, diaphragm, heart and masseter) of pigs, while meat cuts used as human food such as chop, loin, left tricep and left semitendinosus, had a lower burden of T. gondii tissue cysts. These promising results highlight the potential of S48 strain tachyzoites for reducing the number of T. gondii tissues cysts in pork and thus improving food safety.     

Assessment of α-tocopheryl acetate supplementation,addition of salt and packaging on the oxidative stability of raw turkey meat

1. One-day-old turkey poults (n=14) were randomised into 2 groups (n=7) and fed diets containing 20 (E20) and 600 (E600) mg all-rac-α-tocopheryl acetate/kg food for 21 weeks prior to slaughter. Two batches were formed from E20 meat (E20) and E20 plus 10 g salt/kg (E20S). Two similar batches were formed from E600 meat (E600) and E600 plus 10 g salt/kg (E600S). 2. The effects of α-tocopheryl acetate supplementation and salt addition on the oxidative stability of raw turkey patties was investigated during aerobic and vacuum-packaged refrigerated (4°C) storage. 3. Dietary α-tocopheryl acetate supplementation reduced TBARS (thiobarbituric acid reacting substances) numbers for raw overwrapped and vacuum-packaged turkey leg and breast patties. 4. Dietary α-tocopheryl acetate had the greatest influence on TBARS numbers for raw overwrapped turkey leg patties. 5. The addition of 10 g salt/kg increased TBARS numbers for overwrapped and vacuum-packaged turkey leg and breast patties. 6. Vacuum-packaged patties remained more oxidatively stable than similarly treated overwrapped patties throughout the experimental period.     

Day‐length during rearing and the subsequent egg production of meat‐strain pullets

1. The effects of lighting pattern on production to 399 d in caged, female, meat‐strain chickens was investigated. Energy intake was controlled from 56 to 399 d.

2. Four different rearing treatments with a subsequent constant 16‐h photoperiod during laying were used.

3. A 15‐h rearing photoperiod resulted in delayed sexual maturity, increased mature body weight and decreases in both total egg numbers and the proportion of smaller eggs, compared with a 6‐h photoperiod.

4. Continuous light to 56 d, although associated with a high incidence of subsequent blindness, resulted in satisfactory egg production.

5. Abrupt reduction in the photoperiod from 15 to 6 h for the 112 to 167 d period resulted in unsatisfactory subsequent performance, especially when the day‐length was only slowly increased to 16 h during laying.

6. In the two laying treatments, in which the photoperiod was increased gradually from 6 to 16 h during the 168 to 238‐d period, a decrease in the number of smaller eggs occurred, compared with the treatments in which a single abrupt increase in photoperiod was used.     

Acetylation,deacetylation and hydroxylation of sulphamethoxazole and N4‐cacetylsulphamethoxazole in the snail Cepaea hortensis

Summary

The snail Cepaea hortensis is able to acetylate and hydroxylate sulphamethoxazole in a similar way to man. About one percent deacetylation, but no hydroxylation of N₄‐acetysulphamethoxazole takes place. The relative rates of the metabolic pathways for hydroxylation and acetylation of sulphamethoxazole are equal.     

Effect of the administration program of 2 β-adrenergic agonists on growth performance and carcass and meat characteristics of feedlot ram lambs

The aim of the study was to determine the effects of 3 feeding dose programs of the β-adrenergic agonists (β-AA) ractopamine hydrochloride (RH) or zilpaterol hydrochloride (ZH) for the final 30 d before slaughter on growth performance and carcass and meat characteristics of feedlot ram lambs. Eighty-four Dorper × Katahdin ram lambs (30.0 ± 1.6 kg) were blocked by BW and randomly assigned to pens (4 lambs per pen and 3 pens per treatment). Pens within a block were assigned randomly to 1 of 7 dietary treatments: 1) control (CTL) = diet without β-AA; 2) RH constant (RHC) = 20.0 mg/kg of RH, d 1 to 30; 3) RH increasing (RHI) = 10.0 mg/kg, d 1 to 10; 20.0 mg/kg, d 11 to 20; and 30.0 mg/kg, d 21 to 30; 4) RH decreasing (RHD) = 30.0 mg/kg, d 1 to 10; 20.0 mg/kg, d 11 to 20; and 10.0 mg/kg, d 21 to 30; 5) ZH constant (ZHC) = 6.0 mg/kg of ZH, d 1 to 30; 6) ZH increasing (ZHI) = 3.0 mg/kg, d 1 to 10; 6.0 mg/kg, d 11 to 20; and 9.0 mg/kg d 21 to 30; and 7) ZH decreasing (ZHD) = 9.0 mg/kg, d 1 to 10; 6.0 mg/kg, d 11 to 20; and 3.0 mg/kg, d 21 to 30. Overall, β-AA supplementation reduced DMI (P < 0.001) compared with CTL lambs, but lambs fed RHI and ZHI programs had greater (P < 0.05) total BW gain, ADG, and G:F. Carcass weight was improved (P < 0.05) by RHI and ZHI programs, but dressing percentage was enhanced (P < 0.05) by only ZHC or ZHI treatments. Fat thickness and yield grade were reduced (P < 0.05) by ZH or RH regardless of feeding program. Most LM characteristics (pH, moisture loss, and chemical composition) were not different among treatments (P > 0.05), with the exception of fat content that was reduced (P < 0.001) in lambs fed β-AA, and diameter of muscle fibers that was increased (P < 0.05) by ZHI treatment. Constant and increasing doses of ZH reduced (P < 0.05) the a* value of LM and semitendinosus muscles, with no effects on L* or b* values. The mass of liver was reduced (P < 0.05) in ZHI-treated lambs compared with CTL lambs, and plasma urea concentration was reduced (P < 0.05) by RH or ZH administration regardless of feeding program, although there were no other differences in organ mass weight (P ≥ 0.35) or blood metabolites (P ≥ 0.16). Increasing doses of RH or ZH augmented the growth performance response without negative effects on organ mass weight or blood metabolites. Although a ZHI program improved carcass characteristics, the increased LM fiber diameter of lambs fed ZHI program could be unfavorable because of the potential negative effect on tenderness.     

Effects of polymorphisms in the calpastatin and μ-calpain genes on meat tenderness in 3 French beef breeds

The objectives of the study were to evaluate allelic frequencies and to test the association of polymorphisms in the calpastatin (CAST) and μ-calpain (CAPN1) genes with meat tenderness in 3 French beef breeds. A total of 1,114 Charolais, 1,254 Limousin, and 981 Blonde d'Aquitaine purebred young bulls were genotyped for 3 SNP in the CAST gene and 4 SNP in the CAPN1 gene. Two of these markers, 1 in each gene, can be found in Australian or American commercial genetic tests. Others have previously been reported in American studies or are newly evidenced SNP. The quantitative traits studied were Warner-Bratzler shear force and a tenderness score evaluated by trained sensory panels. All the SNP were informative in the 3 breeds. Associations of individual markers or haplotypes with traits were analyzed. The results differed in the 3 breeds. The G allele of a CAST marker (position 97574679 on Btau4.0) was found to exert a significant effect on the shear force (+0.18 phenotypic SD; RSD) and tenderness score (-0.22 RSD) in the Blonde d'Aquitaine breed. In the same breed, this marker was associated with another CAST SNP (position 97576054 on Btau4.0) such that the GA haplotype appeared to be associated with tougher meat. Two CAPN1 markers (positions 45221250 and 45241089 on Btau4.0) had a significant effect on both traits in the Charolais breed (from |0.11| to |0.25| RSD). In the same breed, these markers were associated with another CAPN1 SNP (position 45219395 on Btau4.0) such that the ACA and AGG haplotypes appeared to be associated with a tender meat and a tougher meat, respectively. Consequently, the present results indicate that the effects of the markers studied are breed-specific and cannot be extended to all Bos taurus breeds. Further studies are also required to identify other more appropriate markers for French beef breeds.     

Effects of dietary sulphur‐containing amino acids on performance and breast meat deposition of broiler chicks during the growing and finishing phases

1. Two growth trials were performed to measure the effects of dietary methionine and cystine (SAA) on growth rate, food conversion efficiency and breast meat deposition in male broilers.

2. In experiment 1, broilers were grown on 6 experimental diets covering a range from 6.9 to 9.6 g SAA/kg. The diets were fed from 15 to 33 d of age. Similarly, in experiment 2, 6 diets containing 6.0 to 8.5 g SAA/kg were fed to finishing broilers 33 to 43 d of age. In each experiment 60 birds per treatment were processed, and carcase yield and breast meat percentage were determined.

3. Significant responses in weight gain, efficiency of food conversion and breast meat percentage were detected, which could be described well by exponential regression curves. Dietary SAA requirements to obtain maximum efficiency of food utilisation and maximum breast meat deposition were estimated to be about 9.0 g/kg from 15 to 33 d of age, and about 8.0 g/kg from 33 to 43 d of age.

4. Economic aspects were considered to calculate optimum SAA specifications from the results. In both trials, the dietary optimum of SAA was found to be higher for birds to be further processed than for birds to be marketed as whole carcases.     

Effects of dietary enrichment with n–3 fatty acids on the quality of raw and processed breast meat of high and low growth rate chickens

1. The enrichment of raw poultry meat with n–3 fatty acids (n–3 FA) has been investigated in detail, particularly in high growth rate genotype standard broiler chickens, whereas low growth rate genotype Label Rouge chickens have received less attention. With the increased development of processed poultry products, it is necessary to ensure that the nutritional and sensory quality of meat enriched with n–3 FA is not affected by processing.

2. Two experiments were undertaken for this purpose. In the first experiment, 696 male Ross 708 chickens were reared under standard conditions, and in the second, 750 male JA 657 chickens were reared under Label Rouge conditions. All birds received the same starting and growing diets containing palm and soya oils in each experiment. Birds were distributed into three groups from 21 or 57 d of age for standard and Label Rouge chickens, respectively, and given a control, linseed oil or extruded linseed diet. Diets were also supplemented with vitamin E (100–200 mg/kg). Birds were slaughtered at 56 or 84 d of age for standard and Label Rouge chickens, respectively. A total amount of 60 kg of breast meat from each group was processed into white cured-cooked meat.

3. The dietary treatment had no effect on the growth performance of chickens or meat yield. The use of extruded linseed or linseed oil only decreased the carcass fatness of the standard chickens but had no effect on the carcass fatness of Label Rouge chickens. The nutritional quality of raw and cured-cooked meat was improved (increased concentration of n–3 FA), whereas the technological quality of the meat (pH, juice loss after cold storage, susceptibility to oxidation, colour, processing yield and shear force value) and sensory quality of the processed products were not or slightly affected.

4. Linked to lower breast yield, to lower lipid content in breast meat and to higher slaughter age, Label Rouge chickens seemed to be less efficient for n–3 FA deposition in breast muscles than standard chickens.     

Quantitative effects of pelleting on performance,gastrointestinal tract and behaviour of meat‐type chickens

1. In an attempt to quantify the effects of “degree” of pelleting, two experiments were conducted. Diets were prepared by mixing together a mash composed mainly of maize (experiment 1) or sorghum (experiment 2) with soft pellets, or soft pellets mixed with hard pellets.

2. The pelleting degrees (PDs) were as follows: 0 mash; 0·5 mixture of soft pellets and mash 1 to 1; 1 soft pellets pelleted once; 1·5 mixture of soft and hard pellets 1 to 1; 2 hard pellets pelleted twice.

3. In experiment 2, the weight and length of the digestive organs were determined as well as digestive enzyme activities. In both experiments, the behaviour recorded was eating, standing, sitting and drinking.

4. Food intake and body weight gain were related to the degree of pelleting in a curvilinear manner. PD had a positive effect up to a peak (1 to 1·5 PD), after which its effect decreased. Food efficiency was not related to PD. In experiment 1, food efficiency of PDs 1 to 2 were superior to PDs 0 to 0·5 and in experiment 2, PDs 1·5 to 2 were superior to PD 0.

5. The relative weight of the gizzard was reduced by pelleting, whereas pelleting increased the relative weight of abdominal fat. The content of the crop was not affected by PD, whereas that of the proventriculus was lowest in the PD 2 group. Gizzard content was inversely related to PD. Pelleting reduced the length of the jejunum and ileum: which were shortened by about 15% with PDs 1 to 2, as compared to PD 0. The weight/length ratio of the jejunum and ileum tended to increase with increasing PD to a peak at PD 1·5, and to decrease thereafter.

6. Trypsin activity in the pancreas and amylase activity in the intestinal content were reduced by pelleting.

7. Chicks fed pelleted diets were less active: they ‘sat’ more and spent less time eating than their mash‐fed counterparts.     

Chemical composition and nutritional value in vitro of mechanically‐deboned poultry meat

1. The composition by proximate analysis, amino acid content and digestibility by mammalian proteolytic enzymes of pastes from mechanically‐deboned chicken breasts wings, necks and backs, and hand‐deboned breast were measured. Values obtained were used to calculate indices of nutritional value.

2. All pastes compared favourably with similar protein materials used for human food. Mechanical deboning did not alter the nutritional indices.

3. The protein quality and digestibility of the breast were somewhat higher than those for other parts.     

Effects of evisceration and storage temperature on changes in meat quality of traditional farm‐fresh Turkeys

1. Conditions affecting the keeping quality of traditional farm‐fresh turkeys were investigated.

2. Storage of uneviscerated Wrolstad turkeys at 4 °C for 10 days caused no statistically significant changes in meat flavour or texture.

3. During further storage at —2 °C, however, there was a slight but significant change in flavour, which became more marked with time in birds which had been eviscerated after the initial period at 4 °C.

4. Both eviscerated and uneviscerated birds became slightly tougher during storage.

5. Initial holding at 4 °C increased the numbers of psychrotrophic bacteria on the skin by about 10³ but subsequent changes at — 2 °C were slight for uneviscerated birds.

6. Eviscerated carcases had higher counts than uneviscerated birds after storage at — 2 °C and, although ‘off’ odours were not detected, spoilage appeared to be imminent at the end of the 20‐d period.     

Influence of drinking water salinity on carcass characteristics and meat quality of Santa Inês lambs

This study aimed to evaluate the effects of different salinity levels in drinking water on the quantitative and qualitative characteristics of lamb carcass and meat. Ram lambs (n = 32) were distributed in a completely randomized design with four levels of salinity in the drinking water (640 mg of total dissolved solids (TDS)/L of water, 3188 mg TDS/L water, 5740 mg TDS/L water, and 8326 mg TDS/L water). After slaughter, blending, gutting, and skinning the carcass, hot and biological carcass yields were obtained. Then, the carcasses were cooled at 5 °C for 24 h, and then, the morphometric measurements and the cold carcass yield were determined and the commercial cuts made. In the Longissimus lumborum muscle color, water holding capacity, cooking loss, shear force, and chemical composition were determined. The yields of hot and cold carcass (46.10 and 44.90%), as well as losses to cooling (2.40%) were not affected (P > 0.05) by the salinity levels in the water ingested by the lambs. The meat shear force was 3.47 kg/cm² and moisture, crude protein, ether extract, and ash were 73.62, 22.77, 2.5, and 4.3%, respectively. It is possible to supply water with salinity levels of up to 8326 mg TDS/L, because it did not affect the carcass and meat characteristics of Santa Inês lambs.     

Investigating potential roles of extruded flaxseed and α-tocopherol acetate supplementation for production of healthier broiler meat

1. The present study was conducted to evaluate the role of extruded flaxseed (EFS) and α-tocopherol acetate (ATA) for the enhancement of polyunsaturated fatty acids ratio (PUFA) over saturated fatty acids (SFA) in broiler meat as a source of healthier meat.

2. A total of 96 one-d-old Cobb 550 broilers were randomly divided into 8 treatments with three replicates having 4 birds in each. EFS (extruded at 155°C) at 100, 150 and 200 g/kg alone and in combination with ATA at 200 mg/kg were supplemented through normal feed from the third week onward.

3. During the 6-week growth period, body weight gain (BWG), feed intake (FI), feed conversion ratio (FCR) and mortality were recorded. At slaughter, weight of liver, heart and kidney and fat content in breast and leg meat were measured. Fatty acid profiles in breast and leg meat were developed to estimate the PUFA to SFA ratio.

4. The results revealed that FI and FCR changed significantly in all groups and BWG increased in all the supplemented groups. The weight of liver, kidney and heart increased more in the supplemented group containing the maximum level of EFS with ATA compared with single supplementation of EFS.

5. The fat content in breast and leg meat decreased as the inclusion level of EFS increased. The level was low in leg meat compared with breast meat. Mortality decreased in all supplemented groups.

6. The PUFA to SFA ratio was significantly higher in leg meat (3.23) compared with breast meat (1.81) and the study therefore indicates that ATA and EFS supplementation could be used to improve the PUFA to SFA ratio in broiler meat.

     

Is meat quality from Longissimus lumborum samples correlated with other cuts in horse meat?

The present work aims to investigate if the variation of each parameter in Longissimus lumborum muscle could correspond to the same or to a similar variation of the parameter in the other muscles. The work presents results of Pearson's correlations between Longissimus lumborum samples and other muscle samples, such as Biceps femoris, Rectus femoris, Semimembranosus, Supraspinatus and Semitendinosus in horse meat. A total of 27 male IHDH (Italian Heavy Draught Horse) breed foals were employed. They were slaughtered at 11 months of age and the above‐mentioned muscles were sampled. The Longissimus lumborum muscle showed to be representative of other muscles and of the whole carcass for some chemical parameters (moisture, protein and ash) and for some fatty acids profile patterns such as C12:0, C14:0, total monounsaturated fatty acid and polyunsaturated fatty acid, but poor correlations were recorded for intramuscular fat concentration, rheological and colorimetric parameters. Although almost all the qualitative parameters in meat are affected by the anatomical site and by the muscle, the Longissimus lumborum is often not representative in horse meat with regard to modifications of this parameters.     

The microstructure of the cuticle‐less shell of the eggs of the domestic hen

1. Open pores were a notable feature of the shell of hens' eggs which were naturally devoid of cuticle.

2. In contrast with normal eggs, the surface of the cuticle‐less shell was irregularly contoured and, in many instances, deeply fissured.