张掖肉牛屠宰性能测定和肉品质评定

[目的]为了解张掖肉牛现阶段产肉性能,及时分析品种培育进展和成效,张掖市通过委托第三方专业检测机构开展肉牛屠宰性能测定和肉品质评价试验,根据其结果进行分析研判。[方法]从3家肉牛核心育种场选择具有继代关系的公犊牛持续育肥后根据屠宰性能测定和肉品质评定试验结果分析世代遗传进展和品种培育成效。[结果]试验历时5年,完成连续2个世代各20头育肥牛的屠宰测定和肉质评定。共测定性能指标35项,对其中25项测定值进行样本配对检验,试验B较试验A的体重、体高、胸围、胴体重、净肉重5项指标差异显著,管围、肉质大理石花纹、pH、系水力、蒸煮损失5项指标差异极显著,月龄、十字高、体斜长、腹围等其它15项指标有差异但尚未达到显著水平。而且试验B组较A组的屠宰月龄缩短1.64月,而体重增加59.91 kg,且体尺表型值相应增加。根据日增重遗传力(h²)0.42计算出宰前体重表型增加量为25.16 kg(即剔除由于育种场饲养管理改进、环境影响友好和其它有利因素叠加实现的提高量为34.75 kg),相当于产肉量增加11.6 kg。[结论]从2次结果反映出品种选育有成效,由活重体现出遗传进展。...     

Assessment of cattle welfare at a commercial slaughter plant in the northwest of Mexico

Slaughter plants have been undergoing radical transformations in recent years due to the need to increase efficiency and incorporate new technologies for the improvement of the infrastructure, animal welfare, and product quality. The aim of this study was to assess the cattle welfare status during the unloading, lairage, stunning, bleeding and quantify bruising incidence at a commercial slaughter plant in the northwest of Mexico. We monitored 8,118 cattle during the unloading, lairage, stunning, bleeding, and carcass bruise incidence. Our results showed that in the unloading stage, 2% of the cattle vocalized, 5% were prodded with an electric goad, and 4% either slipped or fell. In the lairage stage, 12% of the animals vocalized, 80% prodded with an electric goad, and 8% of the animals slipped or fell. In the stunning stage, 10% of the animals vocalized, 67% prodded with an electric goad, and 15% of the animals slipped or fell. Ninety-five percent of the animals were stunned with a single shot, and 51% of the animals were effectively desensitized. Ninety-two percent of the carcasses had some type of bruise. Although the slaughter plant had adequate infrastructure and stringent operational standards, in all of the stages except unloading handling had an impact on the welfare of the animals being slaughtered.     

Influence of increasing slaughter age of chickens on meat quality, welfare, and technical and economic results

Because of the increasing demand for raw cuts and processed products, there is a trend to producing very heavy broilers. Breeds that are used for such kinds of production have been intensively selected for growth rate and breast meat yield, and birds are reared for a longer period than standard broilers. This study was to evaluate the effects of increasing slaughter age on technical and economic factors, including production efficiency and environmental costs, bird welfare, and breast meat quality in a modern heavy broiler line. Five groups of 300 male Ross 708 chickens were reared until slaughter ages of 35, 42, 49, 56, or 63 d. Increasing age at slaughter from 35 to 63 d resulted in a 7.4-fold increase (P < 0.01) in mortality rate (5.21 vs. 0.70%). It also increased (P < 0.001) the slaughter weight and ADFI of birds 2.5- and 1.4-fold, respectively, without affecting their G:F. Under our experimental conditions, economic profit evaluated through the net gain reached a maximum at 42 d. The moisture and ammonium content of litter increased (P < 0.05 and P < 0.01, respectively) rapidly during rearing concomitantly with increased (P < 0.05) occurrence and severity of contact dermatitis and decreased (P < 0.05) walking ability and activity of birds. Thermal comfort also decreased (P < 0.05) greatly as early as 42 d of age. Changes in carcass quality occurred mainly between 35 and 56 d of age, with a progressive increase (P < 0.001) in breast and leg yield, whereas body fatness was barely affected by age. Major changes in breast meat traits were observed between 35 and 49 d of age, with an increase in muscle pH at 15 min (P < 0.01) and 24 h (P < 0.001) postmortem and reduced (P < 0.001) lightness and drip loss. The protein and lipid content of raw breast meat also increased (P < 0.05 and P < 0.01, respectively) with age. Taking into account the main aspects of sustainability, we could recommend slaughtering chickens of heavy line at 42 d of age.     

Acid-base equilibrium in the blood in cattle in relation to the incidence of DFD (dark, firm, dry) meat

We studied changes in the parameters of the acid-base balance of the blood in cattle before animal transport to the slaughterhouses, after transport, after stunning and before bleeding. At the same time we studied the occurrence of DFD meat by measuring the pH value of the muscle and by determining the meat color. We found out that the disorder of acid-base balance was less manifest, with respect to the large capacity of the buffer systems of the blood, than the changes caused by glycogenolysis in the muscle.     

Effect of commercial transport in Spain on cattle welfare and meat quality

The purpose of this work was to determine the effect of transport of cattle from the farm to the abattoir on the animal's welfare and post mortem meat quality (instrumental and sensorial). Thirty-nine commercial journeys were followed in Spain from July 2000 to July 2001 at varying distances from a local abattoir in the city of Zaragoza. Blood samples were taken at the farm and at sticking and meat pH24 was measured at 24 hours post-mortem. Samples from the M. longissimus dorsi thoracis were taken from 48 slaughter bulls and analysed in terms of instrumental and sensorial qualities. Cortisol, glucose, CPK, lactate and N:L ratio increased during transport compared to control values. Cortisol was higher after 1-2 h transport compared to journeys that were less than 1 h or more than 2 h long. In general the parameters indicated slightly more stressful conditions under winter conditions than in the summer. Meat tenderness measured by a Warner-Bratzler device demonstrated that there was no significant effect of either transport time or season. There was no significant change in pH24 or meat colour at 24 h with transport time. Transport time had a significant effect (p < 0.05) on overall liking and animals transported in summer had slightly more tender meat and higher overall liking.     

柠檬酸稀土对锦江黄牛屠宰性能、肉品质及脂肪代谢的影响

本试验旨在研究柠檬酸稀土对锦江黄牛屠宰性能、肉品质及脂肪代谢的影响。选用年龄、体质量相近的健康育肥期锦江公牛为试验动物,共12头,平均体质量为(374.75±4.02)kg,随机分成2组,即对照组和试验组,在试验组饲粮中的添加柠檬酸稀土400 mg/kg,对照组不添加柠檬酸稀土。试验期为期70 d。饲养试验结束进行屠宰,测定其屠宰性能,分析测定肉品质指标和脂肪代谢相关酶及激素指标。结果显示:饲粮中添加柠檬酸稀土显著提高了平均日增质量(P<0.05),显著降低了料质量比(P<0.05);饲粮中添加柠檬酸稀土可显著提高血清中GH和瘦素的水平(P<0.05);饲粮中添加柠檬酸稀土显著降低了育肥期锦江黄牛的脏脂率和脂肪率(P<0.05),有降低背膘厚及板油率的趋势(0.05≤P≤0.1);饲粮中添加柠檬酸稀土显著提高了牛肉中粗蛋白的含量(P<0.05),降低了粗脂肪及干物质的含量(P<0.05),同时具有提高剪切力的趋势(0.05≤P≤0.1);饲粮中添加柠檬酸稀土显著降低了肝脏中MDA的活性(P<0.05),对FAS活性具有降低的趋势(0.05≤P≤0.1);饲粮中添加柠檬酸稀土显著提高了肝脏中LPL的活性(P<0.05),对TL也有升高的趋势(0.05≤P≤0.1)。结果表明,饲粮中添加400 mg/kg的柠檬酸稀土可改善锦江黄牛生产性能和屠宰性能,提高肌肉中粗蛋白含量,同时还有明显的降低育肥期锦江黄牛体内脂肪含量的作用,提高肉牛养殖效益。     

Bruises in beef cattle at slaughter in Mexico: implications on quality,safety and shelf life of the meat

In emergent economies and developing countries of Africa, Asia and Latin America, the major cause for carcass rejection from the international market is bruising; nevertheless, many of these carcases are destined to local markets and meat processing industries for human consumption. Therefore, the aim of the present study was to assess the effect of bruised meat on pH, microbiologic count and biogenic amine (BA) profiles along 21 days of ageing (sampling 1st, 7th, 14th and 21st day) with two packaging method (plastic bag vs vacuum) at 4 °C. A total of 50 bruised carcasses were sampled from 1000 young bulls (Brown Swiss X Zebu) of 18–24 months old and an average live weight of 450?±?66 kg. The results showed significant differences between packaging systems and bruised vs non-bruised meat. The bruised meat caused higher biogenic amine concentrations than did non-bruised meat. We conclude that bruised meat favoured increments of biogenic amine concentrations, even more than did non-bruised meat. The plastic bag?+?vacuum system limited the increments of BA concentration during storage time therefore it improved shelf life of meat. These results emphasized the importance of implementing best management practices during pre-slaughter operations of cattle in order to reduce a possible risk factor for bruised meat.     

宰前运输应激对肉牛屠宰性能和牛肉品质的影响

30头西门塔尔杂交牛随机均分为2组,对照组(不运输组)和试验组(运输组),试验组肉牛经12 h的宰前运输。结果表明,与对照组相比,试验组屠宰率和净肉率分别显著降低了2.28(P0.05)和1.68个百分点(P0.05);试验组在12 h(P0.01)、24 h(P0.05)的肌肉滴水损失显著升高,但2组间在72 h的肌肉滴水损失差异不显著(P0.05);在45 min时的肌肉剪切力值,试验组比对照组高17.11%,差异显著(P0.05),在24,48,72 h时,2组间差异均不显著(P0.05);在12 h的肌肉p H值,试验组比对照组低9.33%,差异显著(P0.05),但在45 min,24,48,72 h的p H值,2组间差异均不显著(P0.05);2组间肌肉颜色差异不显著(P0.05);试验组肌糖元含量比对照组低24.03%(P0.05),肌肉乳酸含量比对照组高28.65%(P0.05),而肌肉乳酸脱氢酶、肌酸激酶2组间均差异不显著(P0.05)。结果表明,肉牛经12 h的宰前运输,降低了肉牛的屠宰性能和牛肉品质。     

Cattle cruelty and risks of meat contamination at Akinyele cattle market and slaughter slab in Oyo State,Nigeria

Cattle transported to the government-run cattle market and slaughter slab in Akinyele, Oyo State, Nigeria on their final voyage are facing a disturbingly cruel, filthy and unsafe environment that is also raising the risk of contamination of meat sold for human consumption. This report gives a picture of what the cattle have to go through before they are slaughtered. This study also reveals cattle awaiting slaughter in abysmal health conditions, cows pulled with extreme force towards lairage and slaughter slab. Equally disturbing is the filthy situation inside the abattoir where the risk of contamination of meat is significant. Also, poor meat handling, transportation and sales practices subject meat to contamination leading to poor quality and exposure of human consumers to health risk. Development of hygienic slaughter slab operations, improved transportation system for both livestock and meat is therefore recommended; not only for Akinyele, but all abattoirs and slaughter slabs in Nigeria.     

Critical points in the transport of cattle to slaughter in Spain that may compromise the animals' welfare.

The welfare of cattle depends greatly on the attitudes and training of stockpersons and on the availability of appropriate facilities. Much has been learned about stress during transport, but less attention has been paid to identifying and correcting critical points, partly because they vary widely both nationally and internationally. A survey of cattle transport in Spain was made in an effort to determine which parts of the process most compromised the animals' welfare. Data were collected on the methods and facilities for loading and unloading, transport times, types of vehicle and slaughterhouse practices. Loading facilities were adequate and loading times generally short but some farms continued to use an electric goad and weather-proofing was generally poor. The average journey time within Spain was three-and-a-half hours, but many trips were made abroad (especially to Italy), few drivers received specific training courses and the types and quality of vehicles varied widely. The average unloading time was very short but the animals were not always inspected for injuries or dirtiness. Lairage times were normally more than eight hours but few slaughterhouses had air-conditioning equipment to prevent excessive heat or dehydration. Almost all stockpersons avoided either regrouping animals or housing or transporting animals at high densities.     

The complex relationship between welfare and reproduction in cattle

Using reproduction parameters as indicators for cattle welfare has limitations and, at best, these parameters should only be viewed as indirect indicators of welfare. On a farm level, measures such as fertility rates emphasize biological performance of the herd but fail to consider the welfare of individual animals. Even on an individual level, the relationship between reproductive effectiveness and animal welfare is complex. Good reproductive performance does not automatically signify good welfare, as domestication and targeted breeding programmes have led to prioritization of high productive and reproductive performance in most modern farm animal species. In this review, we synthesize literature regarding cattle husbandry, reproduction, welfare and their multidimensional relationships. We argue that practices such as artificial insemination or the use of sexed semen may provide potential welfare advantages as these practices reduce the risk of disease transmission and injury or enable selection of specific beneficial traits. Furthermore, they may offer a solution to current practices jeopardizing welfare, such as the management of surplus bull calves in the dairy industry. Conversely, the animals’ ability to perform natural behaviours such as oestrous expression, an aspect arguably contributing to welfare, is often limited on commercial farms; this limitation is particularly evident in housing systems such as tie stalls where movement is restricted. Moreover, common management practices such as oestrus manipulation may lead to negative attitudes in citizens who often regard naturalness as important element of animal welfare.     

Rheological characteristics of fresh and frozen PSE, normal and DFD chicken breast meat

1. Textural and rheological differences among broiler breast meat ranging from pale, soft and exudative (PSE) to dark, firm and dry (DFD) in their fresh and frozen (and thawed) forms were investigated. 2. The PSE meat showed significantly higher lightness values and lower pH and water holding capacity values than normal and DFD meats; DFD meat was also significantly different from normal meat. 3. During cooking, PSE meat lost significantly more liquid and produced a softer gel than normal or DFD meats; texture profile analysis parameters were lower for the PSE meat. 4. The storage modulus values (G', rigidity of elastic response of the gelling material) showed that DFD meat produced a more rigid gel during cooking (especially above 54 degrees C) and later during cooling (back to 30 degrees C) compared with the PSE meat. 5. Freezing resulted in a trend of lower G' values before, during and after cooking. The results indicated that meat proteins were damaged during freezing and PSE meat was more severely affected, or that more protein denaturation occurred in the PSE meat.     

Relationship between food deprivation before transport and aggression in pigs held in lairage before slaughter

Pigs from three farms were deprived of food for up to one hour, 12 hours or 18 hours before being sent for slaughter. In lairage, the animals' behaviour was monitored, and at slaughter a blood sample was collected and analysed for cortisol, lactate and creatine phosphokinase, potential indicators of stress and physical activity. The carcases were assessed for skin damage as an index of fighting, and rigor in the hind leg as an indicator of stress and/or fatigue. Measurements were also made of cold carcase weight, backfat thickness and liver glycogen concentration. General activity was very high on entry to the lairage pen. Drinking and mounting occurred almost immediately. Fighting developed after an exploratory period, and could last up to 60 minutes. There were large differences in the behaviour of pigs from the three farms. Pigs from farm A fought frequently but showed little mounting activity, whereas pigs from farm C were involved in mounting but little fighting. The period of food deprivation had no effect on average skin damage or rigor score, but the frequency of carcases with the highest scores was different The pigs deprived of food for up to an hour had the lowest incidence of severe skin damage and high rigor scores. Boars had a higher incidence of severe skin damage but a lower incidence of carcases with a high rigor score than gilts. Liver glycogen was almost completely depleted in the pigs deprived of food for 12 and 18 hours and was lower in the pigs deprived for up to an hour than in animals fed immediately before slaughter. The period of food deprivation had no effect on the levels of cortisol, creatine phosphokinase or lactate in the blood.     

Occurrence of PSE and DFD meat in swine slaughtered under emergency conditions

The occurrence of qualitative changes in meat was studied in a set of 1008 pigs slaughtered in four sanitation slaughter houses for the period of 12 months. PSE meat was found in 206 pigs (20.43 per cent) and DFD meat only in 9 pigs (0.89 percent) of the total number of pigs examined. The rule was applied that the defect should be demonstrated by two of three commonly used parameters (the pH value, colour and water loss by dripping). The highest occurrence of qualitative changes in meat of PSE type was registered in the group of animals with a defect of the respiratory organs (32.53 per cent) and the lowest in animals with diseases of sexual organs, including parturition complications (5.00 per cent). A similar trend was recorder even in the DFD meat occurrence. As to the seasons, the highest percentage of occurrence of PSE defects was in July and August (35.41 and 29.06 per cent) and the lowest (8.64 and 10.97 per cent) in March and January. The actual disease is proved to be only one of the secondary stress to induce the PSE meat formation.     

Effect of withholding feed from swine before slaughter on carcass and viscera weights and meat quality

Two experiments were conducted to determine the effect of feed withholding on carcass and viscera weights and meat quality in grow-finish swine. Experiment 1 included 528 pigs that were marketed from 24 pens and subjected to either 6 (control) or 24 h of feed withholding before marketing. Experiment 2 included 324 pigs that were marketed from 36 pens that were subjected to 6 (control), 16, or 24 h of feed withholding before marketing. In both experiments, pigs from each pen were marketed over a 14-d period in three groups, each 7 d apart. In Exp. 1, withholding feed for 24 h decreased viscera weight, carcass weight and yield, and feed intake during the 14-d marketing period compared with the control group (P < 0.05). Subjective measures of color, firmness, and marbling in fresh pork did not differ for the two treatment groups. In Exp. 2, withholding feed for 16 or 24 h decreased (P < 0.05) viscera weight compared with that of the control group. Withholding feed for 24 h decreased feed intake during the 14-d marketing period compared with intake of the control group. Withholding feed for 16 h did not decrease carcass weight, but carcass weights in the 24-h group were lower than those of the 16-h group in this Exp. 2 (P < 0.05). Color, firmness, marbling, and shear force did not differ among treatment groups in Exp. 2; however, cooking loss in pork from the control group exceeded that of the 24-h treatment. Gain:feed and ADG were not affected by treatment during the marketing period in either experiment. We conclude that withholding feed for either 16 or 24 h decreases viscera weight and feed intake during the marketing phase in finishing swine. These changes could potentially benefit both the producer and the processor with only minimal effects on carcass weight and pork quality.     

Effect of separate transport, lairage, and slaughter on occurrence of Salmonella typhimurium on slaughter carcasses

The study aimed to reduce cross-contamination between finishers from Salmonella-positive and Salmonella-negative herds during transport, lairage, and slaughter, thereby reducing the prevalence of Salmonella Typhimurium on slaughter carcasses. In Phase 1 of the study, pigs from Salmonella-negative herds were kept in lairage for 2-4 hours either in clean pens (intervention group) or pens contaminated with Salmonella-infected faeces (control group). All pigs were slaughtered on the same slaughterline, and carcass swabs 24 hours after slaughter revealed a low degree of cross-contamination in the pens: there was no difference in Salmonella-positive carcasses between intervention (1.7%) and control groups (0.8%). In Phase 2, control pigs from Salmonella-negative herds were mixed with pigs from Salmonella-positive herds during lairage for 2-4 hours, while the intervention group still consisted of pigs from Salmonella-negative herds. All pigs were slaughtered on the same line: first intervention, then control. Carcass swabs taken 24 hours after slaughter failed to show a reduction in Salmonella-positive carcasses in the intervention group (4.5%) compared with the originally Salmonella-negative pigs in the control group (3.6%). In pigs from Salmonella-positive herds the occurrence of Salmonella was substantially higher at 10.4%. When the results were corrected for 6 carcass samples found positive with S. Heidelberg on the same day, which was attributed to a transient hygiene failure, only 2.2% of the carcasses in the intervention group were Salmonella-positive. We conclude that even though cross-contamination occurs in the abattoir pens, its importance on the slaughter line may be greater. However, the final results of this study should be awaited to conclude whether separate slaughter of pigs from Salmonella-positive and Salmonella-negative herds should be recommended.     

饲喂薰衣草秸秆混合青贮对新疆褐牛生长性能、屠宰性能及肉品质的影响

试验旨在研究用全株玉米秸秆青贮(100%)、混贮1:薰衣草秸秆与野干草(55)、混贮2:薰衣草秸秆与小麦秸秆(46)饲喂新疆褐牛后对其生长性能、屠宰性能及肉品质的影响。根据生长发育相近的原则,将60头新疆褐牛随机分成3组,每组20头牛。结果表明,与混贮2组相比,对照组和混贮1组的终末体重、平均日增重极显著高于混贮2组(P<0.01),饲喂混贮1组的牛屠宰率分别比对照组、混贮2组高0.5个百分点和1.21个百分点(P>0.05)。肉品质方面,混贮1组的粗蛋白显著高于混贮2组的粗蛋白(P<0.05),玉米青贮和混贮1组的粗脂肪(EE)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)和粗灰分(Ash)的含量高于混合青贮2组,但差异不显著(P>0.05)。检测氨基酸结果显示,与对照组相比,混贮1组和混贮2组的天冬氨酸(Asp)、苏氨酸(Thr)、丝氨酸(Ser)、谷氨酸(Glu)、脯氨酸(Pro)、甘氨酸(Gly)、丙氨酸(Ala)、缬氨酸(Val)、蛋氨酸(Met)、异亮氨酸(Ile)、亮氨酸(Leu)、络氨酸(Tyr)、苯丙氨酸(Phe)、赖氨酸(Lys)和精氨酸(Arg)含量略低,但差异不显著(P>0.05),其它各组间均无差异显著性。综上所述,通过青贮的方式可有效改善薰衣草秸秆的饲喂品质及适口性,提高薰衣草秸秆饲草利用率,为进一步开发利用薰衣草秸秆资源提供理论参考。