肉牛产业化发展需要解决的问题

目前,我国肉牛产业化的最大问题是经济效益不理想,本文针对这个问题提出解决措施:将肉牛胴体分级的标准全国统一化,生产高品质牛肉,实现较高利润,打开国内市场,促进国内市场发展;通过科学方法改良牛肉,提高肉牛胴体重;加大在分子方面的研究,加深对牛肉营养价值和遗传机理的研究,实现牛肉品质的分子化[1]。     

利用管理方法提高牛胴体质量

本文对如何从牛场管理手段提高肉牛胴体质量进行了阐述。遗传和管理方法均会提升牛肉胴体的质量,虽然遗传手段可快速提高肉牛胴体质量,但即使不改变肉牛遗传,科学的肉牛管理方法仍会提升肉牛的胴体。反过来说,即使某一肉牛品种肉用性状较好,但忽视饲养管理,其胴体还是不能达到相应标准。管理方法中,育肥天数、分群、补饲、微量元素的使用等是主要的提高肉牛胴体的方式。     

综合信息

以农产品进入超市为契机江苏实行全程质控由中国农业大学食品学院承担的国家“九五”科技攻关项目“优质牛肉系统评定方法和标准”，确定了影响我国牛肉胴体质量和肉质的因素，制定了我国肉牛胴体分级标准，对牛肉工业的发展具有指导性作用，为我国牛肉走向国际市场打下基础。优质牛肉系统评定方法和标准应用后，可以根据胴体等级确定牛肉出售价格，这不仅使消费者的利益得到保证，更重要的是可以指导牛肉生产者和屠宰经营者寻求最佳经营方式和市场贸易方向，如改变生产系统、改良肉牛的品种等，可以大大促进我国的肉牛改良和优质牛肉生产工…     

牛肉分级有了标准可依

由中国农业大学食品学院承担的国家“九五”科技攻关项目“优质牛肉系统评定方法和标准”，确定了影响我国牛肉胴体质量和肉质的因素，制定了我国肉牛胴体分级标准，对牛肉工业的发展具有指导性作用，为我国牛肉走向国际市场打下基础。优质牛肉系统评定方法和标准应用后，可以根据胴体等级确定牛肉出售价格，这不仅使消费者的利益得到保证，更重要的是可以指导牛肉生产者和屠宰经营者寻求最佳经营方式和市场贸易方向，如改变生产系统、改良肉牛的品种等，可以大大促进我国的肉牛改良和优质牛肉生产工作。牛肉分级标准实施后，各生产厂家可根据标准的具体要求，加强质量监控体系，进行关键工序控制，保证产品质量的稳定。 (朱文 )     

牛胴体热剔骨肉块成熟处理试验

本试验研究了36头肉牛屠宰后热胴体分割部位肉块排酸处理提高嫩度的效果,结果显示：热胴体分割牛肉块成熟处理能够达到提高牛肉嫩度的目的。在生产上应用时,实施肉块在胴体上成熟处理72h,分割后的肉块再成熟处理96h即二次成熟处理牛肉品质较好。     

鲁西黄牛胴体质量的研究

对肉牛胴体进行分级是评定肉牛品种和肥育技术的重要手段，但是目前我国尚无全国统一的、公认的肉牛胴体分级标准，这与我国肉牛生产迅速发展的形势很不适应。鉴于日本１９８８年制定并在日本全国实施的肉牛胴体分级标准对我国的肉牛生产具有一定的适用性和参考价值，我们借用日本的标准进行分级试验，其目的是为了掌握日本肉牛胴体分级原理和方法，了解我市肥育牛的等级分布以及影响等级的主要因素，进而探讨提高等级的途径。试验于１９９８年６月在平度市华安肉牛屠宰加工厂进行，现将试验结果报告如下：１　材料和方法１－１　试验牛的情…     

肉牛肥育与高档牛肉分割测定试验

育肥牛２２头，从中选出体重适中，不同杂交类型的牛７头，进行屠宰测定，对高档牛肉生产工艺的中心环节，胴体预冷中吊挂嫩化处理的效果及分割肉工艺进行了研究，比较不同杂交种牛产肉性能，高档肉及优质切块肉产量比例的差异，为制度培育优质肉牛，生产高档牛肉的方案提供了一系列参数。     

加拿大肉牛胴体质量及其生产效率的若干研究进展

加拿大是世界上肉牛业发达的国家之一，在影响肉牛胴体质量的因素及其的研究方面广泛而深入；对肉牛群体生产效率的提高方面亦有相当高的研究水平和应用经验。本文对此作了归纳概述，以期对我国的肉牛研究的科技进步有所参考。     

科技

肉牛胴体性状的遗传机制被揭示近日,牛遗传育种创新团队基于全基因组重测序数据,整合选择信号、单性状关联分析以及多性状关联分析,发现了与胴体性状相关的选择信号及候选基因,揭示了肉牛胴体性状的遗传机制,为肉牛胴体性状的选育奠定了理论基础。相关成果发表在《Genomics(基因组学)》。胴体性状作为肉牛重要经济性状之一,直接决定了牛肉的产量和质量,是肉牛育种中的关键目标。解析肉牛胴体性状的遗传机制与机理并挖掘相关的候选标记与基因,不仅可以为肉牛胴体性状的选育提供相关理论基础,还可以推动肉牛育种进展,切实地提高我国牛肉产量。目前,国内外已大量开展了对肉牛胴体性状遗传基础解析工作,捕获到NCAPG、LCORL等重要候选基因,但利用全基因组重测序数据对胴体性状遗传机制解析的分析方法仍需创新。     

加拿大的优质牛肉生产模式

当前，加拿大的肉牛肥育场经营生产的肉牛产品，主要是用于满足国内和美国市场的需求，为了取得最大的经济效益，在肉牛肥育期，为满意市场需要，制定能够达到特定胴体质量标准的饲养方案是非常必要的，同时，了解和掌握肉牛的生长规律，根据肥育牛的目标体重，确定预饲期或生长期，饲喂高能量日粮，才能达到控制胴体质量的目的。     

关于牛胴优质分割肉块名称的讨论

随着优质肉牛生产技术的示范与推广，肉牛产业化蓬勃发展，但在生产过程中，很多牛胴优质分割肉块名称使用不太规范，亟待统一名称，以促进全国肉牛业的进一步发展。     

不同营养水平对肉牛肥育效果的研究

为了探索酒泉地区舍饲肉牛的肥育模式,用3个不同营养水平的精料对62头小公牛进行了肥育试验,并从日增重、耗料量和经济效益3方面进行了分析.结果表明:3个营养水平对肉牛日增重差异不显著,中营养组日增重略高于其它两组;从耗料情况来看,高营养组耗料最多,中、低营养组耗料基本相同;从经济效益看,中营养组最好,高营养组最差.综合分析表明在酒泉地区肥育肉牛应以中等营养水平为宜.     

肉牛饲喂木薯渣及氨化甘蔗梢的育肥效果

[目的]本试验拟通过木薯渣和甘蔗梢育肥肉牛试验,对屠宰性状、胴体品质评价及品尝评分,为肉牛产业提供参考依据。[方法]试验设以木薯渣为基础日粮（Ⅰ组）和以氨化甘蔗梢为基础日粮（Ⅱ组）2个组,分别补给3.0 kg精料,每组7头未去势西杂公牛,育肥110 d后进行屠宰。[结果]表明：①Ⅰ组期末平均活重434.27 kg,平均...     

Genetic parameters for carcass traits of field progeny and their relationships with feed efficiency traits of their sire population for Japanese Black cattle

Genetic parameters for carcass traits of 1774 field progeny (1281 steers and 493 heifers), and their genetic relationships with feed efficiency traits of their sire population (740 bulls) were estimated with REML. Feed efficiency traits included feed conversion ratio (FCR) and residual feed intake (RFI). RFI was calculated by the residual of phenotypic (RFI_phe) and genetic (RFI_gen) regression from the multivariate analysis of feed intake on metabolic weight and daily gain. Progeny traits were carcass weight (CWT), rib eye area (REA), rib thickness (RBT), subcutaneous fat, yield estimate (YEM), marbling score (MSR), meat quality grade, meat color, fat color, meat firmness and meat texture. The estimated heritability for CWT (0.70) was high and heritabilities for all the other traits were moderate (ranged from 0.32 to 0.47), except for meat and fat color and meat texture which were low (ranged from 0.02 to 0.25). The high genetic correlation (0.62) between YEM and MSR suggests that simultaneous improvement of high carcass yield and beef marbling is possible. Estimated genetic correlations of RFI (RFI_phe and RFI_gen) of sires with CWT (− 0.60 and − 0.53) and MSR (− 0.62 and − 0.50) of their progeny were favorably negative indicating that the selection against RFI of sires may have contributed to produce heavier carcass and increase in beef marbling. The correlated responses in CWT, REA and RBT of progeny were higher to selection against RFI than those to selection against FCR of sires. This study provides evidence that selection against RFI is preferred over selection against FCR in sire population for getting better correlated responses in carcass traits of their progeny.     

Evaluation of estimated genetic merit for carcass weight in beef cattle: Blood metabolites, carcass measurements, carcass composition and selected non-carcass components

In Ireland, a new beef genetic index has been developed. Growth rate is expressed as expected progeny difference for carcass weight (EPD_CWT) and is estimated on an across-breed basis. Cross-breeding of dairy cows with both Aberdeen Angus and Belgian Blue beef sires is widely practised. The objective of this study was to compare blood metabolites, slaughter traits and carcass composition of progeny from Holstein–Friesian dairy cows and Aberdeen Angus (AA), Belgian Blue (BB), Friesian (FR) and Holstein (HO) sires. The AA and BB sires were selected, within breed, to be of either high (H) or low (L) estimated genetic merit for carcass weight. A total of 170 male progeny from spring-calving cows and 42 sires (10 AA, 13 BB, 7 FR and 12 HO) were artificially reared indoors and managed together until the end of their second grazing season when they were assigned to either a Light (560 kg) or Heavy (620 kg) slaughter weight. Blood metabolite concentrations were measured six times throughout life and feed intake was recorded during the first and second winter. Carcass measurements and selected non-carcass components were recorded after slaughter and the right side of each carcass was dissected into lean, fat and bone. Differences in blood metabolite concentrations amongst genetic groups were negligible although there were some effects of the prevailing level of nutrition. M. longissimus area scaled for carcass weight was 0.220, 0.221, 0.260, 0.255, 0.212 and 0.208 (SE 0.004) cm²/kg for AAH, AAL, BBH, BBL, FR and HO, respectively. Carcass measurements scaled for carcass weight were greater for L, AA, HO and the dairy strains than for H, BB, FR and the beef breeds, respectively. There was no effect of estimated genetic merit for carcass weight on carcass composition. Statistically significant interactions between genetic merit and beef breed existed for some traits with the genetic merit effect largely evident for AA only. BB and the beef breeds had more lean, less fat and more high value lean in the carcass than AA and the dairy strains, respectively. It is concluded that genetic group had little effect on blood metabolite concentrations but there were some feeding level effects. Estimated genetic merit for carcass weight affected carcass weight, m. longissimus area and carcass measurements scaled for carcass weight but the effects were confined to AA. There were large effects of beef breed and dairy strain on carcass composition.     

Evaluation of estimated genetic merit for carcass weight in beef cattle: Live weights, feed intake, body measurements, skeletal and muscular scores, and carcass characteristics

Genetic merit for growth rate, expressed as expected progeny difference for carcass weight (EPD_CWT), is available for dairy and beef sires used in Ireland. The once predominantly Friesian (FR) dairy herd has experienced significant introgression of Holstein (HO) genes over the past two decades, and cross-breeding of dairy cows, not required to produce herd replacements, with beef bulls is common. The objective of this study was to compare growth rate, feed intake, live animal measurements and slaughter traits of progeny of Holstein–Friesian dairy cows and bulls of two contrasting maturity beef breeds namely Aberdeen Angus (AA) and Belgian Blue (BB), each selected for either high (H) or low (L) estimated genetic merit for carcass weight. Two dairy strains (FR and HO) were also included giving six genetic groups in total. A total of 170 male progeny from spring-calving cows were artificially reared indoors and subsequently managed together at pasture until the end of their second grazing season when they were assigned to one of two mean slaughter weights (i) 560 kg (Light) or (ii) 620 kg (Heavy). Daily feed intake was recorded during the first winter and during finishing. Body measurements were recorded four times during the animals' life, and linear scoring was carried out at 9 months of age and again at slaughter. Carcasses were graded for conformation and fatness (15 point scale). Slaughter and carcass weights per day of age for AAH, AAL, BBH, BBL, FR and HO were 782, 719, 795, 793, 804 and 783 (SE 12.9) g, and 415, 372, 438, 436, 413 and 401 (SE 5.8) g, respectively. Corresponding values for carcass weight, kill-out proportion, carcass conformation class (15 point scale) and carcass fat class (15 point scale) were 314, 283, 334, 333, 317 and 305 (SE 4.7) kg, 526, 518, 553, 550, 519 and 511 (SE 2.9) g/kg, 6.2, 5.4, 8.0, 7.9, 5.3 and 3.7 (SE 0.26), and 9.8, 9.3, 7.4, 7.2, 9.3 and 8.2 (SE 0.26). There were significant interactions between estimated genetic merit for carcass weight and beef breed with the differences between H and L mainly expressed for AA only. Feed intake differences between H and L animals were negligible and largely attributable to the differences in live weight. Following scaling for live weight, beef breeds of high estimated genetic merit for carcass weight had lower skeletal measurements, indicating greater compactness, with the effect more pronounced in AA. It is concluded that using beef sires of estimated high genetic merit for carcass weight on dairy cows increases growth rate and carcass weight of the progeny but the effect may not be similar for all breeds.     

Live weight, body size and carcass characteristics of young bulls of fifteen European breeds

A total of 436 young bulls from fifteen Western European breeds, including beef, dairy and local types from five countries, were studied to assess variability in live weight, live weight gain, body measurements and carcass traits. Animals were logged indoors, and fed a diet based on concentrate and straw offered ad libitum from 9 months of age to slaughter at 15 months of age. The weight, body length, height at withers and pelvis width, of the animals were recorded at 9, 12 and 15 months of age. After slaughter, 15 carcass variables were recorded, including carcass weight, EU classification scores, morphological measurements and dissection data. Data were analysed by GLM, regression and principal component analysis procedures.Significant differences were found between breeds for all variables studied, however, the body size measurements and the carcass traits were more useful to discriminate among cattle breeds, than either live weight or daily gain. With respect to the body size and carcass traits the studied breeds could be grouped as:

– Specialized beef breeds, comprising Piemontese, Asturiana de los Valles, Pirenaica, Limousin, South Devon, Charolais and Aberdeen Angus, all of which were characterized by high muscularity, wide pelvis and medium height and a low to medium level of fatness.

– Local and dairy breeds, comprising Jersey, Casina, Highland, Holstein and Danish Red, the latter two breeds were tall animals, while the former three breeds were small in size. In general the group was poorly muscled and tended to have a high or medium level of fat.

– Intermediate group, Avileña, Marchigiana and Simmental: these breeds were characterized by an intermediate muscle conformation and fatness level and were relatively tall.

This study provides a detailed assessment or a wide range of variables in the major breeds, and several minor breeds, that are used in breeding programmes across Europe and elsewhere, and will provide information that will be of use to define breeding strategies to meet the demands of the European beef market.     

影响肉牛经济效益因素的分析

在当前牛肉市场贸易条件下影响肉牛经济效益的因素较多 ,诸如肉牛的品种、年龄、性别、架子牛体重、育肥期内饲养水平、牛肉大理石花纹丰富程度、育肥期长短、屠宰加工分割技术、销售策略和技巧、无谓损失等等。本文依据实际称量测定的山东省东营市广饶县凯银清真肉业公司屠宰肉牛 1 65 0头 (北方大地育肥公司饲养并委托屠宰 )的牛肉产量资料和牛肉销售价格进行分析而得。分析结果 :在诸多影响肉牛经济效益因素中排在第一位的是牛肉大理石花纹丰富程度 ( 1级牛高于 6级牛 5 5 5元 /头 ) ;第二位是育肥牛的年龄 ( 2对牙牛高于未换牙牛 2 79元 /头 ) ;第三位是架子牛开始育肥体重 (≤ 30 0 kg牛好于≥ 5 0 0 .1 kg牛 2 2 2元 /头 ) ;第四位是背部脂肪厚度(≤ 5 mm牛低于≥ 1 5 mm牛 2 0 1元 /头 ) ;第五位是架子牛育肥时间 (育肥时间≤ 1 80 d比≥ 2 4 1≤ 30 0 d多 1 35元 /头 ) ;第六位是脂肪颜色 (白色、微黄色脂肪牛较黄色脂肪牛多卖 1 2 4元 /头 ) ;第七位是牛品种 (每头鲁西牛比夏洛来杂交牛、利木赞杂交牛、西门塔尔杂交牛分别多卖 1 0 0元、73元、73元 ) ;第八位是性别 (阉公牛较公牛多卖 5 0元 /头 )。     

超声波在肉牛育种中应用的研究进展

超声波技术在肉牛业中的合理应用可以帮助育种者制订遗传改良计划,也为肉牛方面的研究开辟了新的领域。超声波技术的应用已使发达国家的肉牛业取得较大的经济效益,但度量指标的准确度仍需进一步提高。本文将对近年来肉牛业中超声波技术应用与研究作一综述,帮助国内同行了解这种技术的应用现状,促进中国肉牛业的大力发展,同时也提出了肉牛业的未来研究方向。