奶公犊资源利用及肉品质评价

利用奶公犊生产犊牛肉已成为国内外肉牛业发展的一大热点,本文综述了国内外奶公犊的资源利用情况,犊牛肉的分类及肉品质评价指标,以期为我国奶业犊资源的利用提供参考。     

合理利用奶公犊生产高档牛肉

六十年代以来,世界肉牛饲养业蓬勃发展,但远远满足不了人们对牛肉的需要,因而一些国家的淘汰奶牛与奶公犊纷纷转为肉用。尤其是奶公犊不仅育成量大,而且肉质品味好,深受人们欢迎。据统计,1986年全世界肉类总产量为15497.4万吨,其中牛肉占31.4%,人均占有牛肉为9.9千克;英国1982年牛肉总产量为96.1万吨,其中奶公犊提供的牛肉占63.1%。随着我国人民生活水平的提高,牛肉需求量不断增加,但是由于我国肉牛生产基地很     

犊公牛直线育肥试验

50年代牛肉生产主要依靠肉牛业,而70年代则由肉牛、奶牛肉、奶公犊肉等多条渠道提供。其中奶公犊提供的牛肉已占相当比重。英国1982年牛肉总产量为96.1万吨,其中奶公犊提供的牛肉占63％。我国牛肉来源主要依靠牧区菜牛或农区淘汰的耕牛供给。全国有8600万头牛,产肉只有40万吨,平均每头年产肉不到5公斤。近年在城市郊区和奶牛生产集中的地区,奶公犊亦被用来在半舍饲条件下饲养一年半以上,体重达400公斤左右而出口。但是,由于精料给量少,生长速度慢,饲养周期长,肉的质量差,难以满足制做牛排等高档菜肴的需求,而且售价低     

犊公牛直线育肥试验

我国随着人民生活水平的提高,对畜产品的需求结构发生了变化,已从“数”转向“质”。人民对畜产品的需求正渐进到选择性购买阶段,市场对畜产品生产的调节功能日益加强,特别是对高档牛肉的需求与日俱增。目前,世界牛肉消费量约占肉类消费总量的三分之一。五十年代牛肉华产主要依靠肉牛业,而七十年代则角肉牛,奶牛肉、奶公犊肉等多条渠道提供.其中奶公犊提供     

中国荷斯坦奶公牛肉用研究进展

奶公犊资源的充分利用,不仅能缓解国际市场上牛肉供应不足的紧张局面,而且可以满足广大消费者对高品质牛肉的需求。如何利用现有的奶公犊资源,借鉴国外先进的产业模式和饲养技术,构建我国特色的肉牛产业,成为当前养牛人关注的焦点。我国在奶公犊育肥利用上起步较晚,但随着牛源紧缺,围绕奶公牛生产的相关研究已经陆续展开,在犊牛肉生产技术、小牛肉生产技术、普通牛肉生产技术以及高附加值牛肉生产技术等4个方面取得了长足进展。本文就近几年中国荷斯坦奶公牛在这4方面的研究进展进行了综述。     

奶公犊育肥

一、目的:目前,世界上发达国家的牛肉产量占总肉量的30％以上,而我国仅占4％,杭州市只占1.4％,随着城乡人民生活水平的提高和旅游事业的发展,牛肉的供需矛盾日益突出。为加快肉牛生产的发展,充分利用奶公犊资源,探索在农村粗放的饲养条件下,奶公犊育肥的技术和经济效益,于1985年8月至1987年1月在萧山县农垦一场对20头奶公犊进行育肥试验。     

奶公犊的培育及开发利用

奶公犊的培育资源丰富,目前,在大多数奶牛生产体系中,广大奶农为了避免奶公犊消耗牛奶而把奶公犊直接淘汰甚至宰杀,奶牛场或农户放弃对奶公犊的培育,以低价出售,造成犊牛资源浪费,可将这一资源开发利用,将低价出售的奶公犊饲喂为肉牛出售,提高经济效益,促进畜牧业发展。犊牛的饲养管理在养牛业中起着非常重要的作用,充分养好犊牛对后期的育肥和生产性能均有积极的促进作用。     

奶公犊的培育及开发利用

奶公犊的培育资源丰富,目前,在大多数奶牛生产体系中.广大奶农为了避免奶公犊消耗牛奶而把奶公犊直接淘汰甚至宰杀,奶牛场或农户放弃对奶公犊的培育,以低价出售,造成犊牛资源浪费,可将这一资源开发利用,将低价出售的奶公犊饲喂为肉牛出售,提高经济效益,促进畜牧业发展.犊牛的饲养管理在养牛业中起着非常重要的作用,充分养好犊牛对后期的育肥和生产性能均有积极的促进作用.     

向奶牛要牛肉,构建资源节约型和谐牛业

本文从中国肉类生产消费现状以及奶牛业和肉牛业的发展特点及趋势出发,针对中国养牛业发展中出现的新问题和情况,就提出的“向奶牛要牛肉”的发展前景进行了论证分析,阐述了中国奶公犊利用的现实意义,指出了目前奶公犊利用存在的问题及发展前景与对策。     

饲喂代乳料对奶公犊的培养效果研究

目前在大多数奶牛生产体系中,广大奶农为了避免奶公犊消耗牛奶而直接将其以低价出售甚至宰杀,造成犊牛资源浪费.应充分开发利用这一资源,对奶公犊进行良好的饲养管理,饲喂为肉牛出售,提高经济效益,促进畜牧业发展.     

育成荷斯坦奶公牛与其他3个品种牛的肉品质比较研究

通过对育成荷斯坦奶公牛与西门塔尔牛、新疆褐牛及新疆土种牛肉品质部分指标的比较分析研究,旨在探讨荷斯坦奶公牛的肉品质。选择在相同营养模式下18月龄左右4个品种牛各3头进行屠宰,取右半边胴体的背最长肌作为肉品质试验样品,分别对牛肉的肉品质、常规营养成分及氨基酸含量进行测定和分析。结果表明,荷斯坦奶公牛肉色、失水率、系水力、熟肉率、大理石花纹等指标均优于新疆褐牛、新疆土种牛,次于西门塔尔牛;荷斯坦奶公牛嫩度优于新疆土种牛;粗蛋白质、粗灰分含量分别为20.14%、1.11%,且各品种间差异均不显著(P>0.05),干物质含量为26.30%,显著高于新疆褐牛和新疆土种牛(P<0.05),低于西门塔尔牛(P>0.05),粗脂肪含量为10.04%,显著高于其他品种牛(P<0.05);荷斯坦奶公牛含有人体需要的各种氨基酸,其中蛋氨酸、谷氨酸、甘氨酸、组氨酸、牛磺酸等含量丰富,氨基酸组成比例良好。     

甘肃省奶公犊资源利用现状探讨

针对目前甘肃省奶牛饲养量较多,奶公犊利用技术薄弱,而肉牛牛源又相对紧张的问题,对甘肃省奶公犊资源生产利用现状进行了分析,就目前甘肃省奶公犊资源利用中存在的主要问题,提出甘肃省奶公犊资源利用的前景与发展对策。     

张掖市百万头肉牛基地育肥牛来源调查

为了查清目前张掖市百万头肉牛基地育肥牛的来源,对张掖市百万头肉牛基地15个肉牛育肥场的5560头育肥牛来源开展了调查。调查表明：来自当地散养户的犊牛占80.5%,来自外地的犊牛占10.6%,来自肉牛育肥场自繁的犊牛占5.8%,来自当地奶牛场的公牛犊占3.1%。     

宁夏海原肉牛品种改良的实践与探索

近年来,海原县肉牛产业得到快速发展。为支撑未来肉牛产业发展需求,迫切需要从品种改良技术层面破解当前育种工作中遇到的问题,为今后高端肉牛产业发展指明方向。本文分析了海原县当前繁育母牛资源现状,从肉牛产业发展目标以及制约产业发展的瓶颈问题出发,探索高端肉牛产业的内在含义,提出以西门达尔牛为母本,安格斯公牛为父本的“海原黑牛”育种方向及其在实践基础上的现实可能性。同时通过现有安格斯纯种繁育扩大母牛和选育良种安格斯公牛,为大量杂交提供优秀的公牛基因资源。希望对当前海原肉牛产业发展具有一定指导意义。     

肉用型牛新品种——辽育白牛的培育

辽育白牛是以夏洛来牛为父本,以辽宁本地黄牛为母本级进杂交后,形成含夏洛来牛93.75%、本地牛6.25%血统,适应当地气候和饲养条件的肉牛新群体。初生重平均：公犊43.6kg,母犊40.3 kg。成年体重：种公牛平均1 084 kg,母牛平均为497 kg,其BPI（肉用指数）分别为7.3和3.9 kg/cm,达到肉用型牛BPI标准。目前育种基础群共有辽育白母牛4 200余头,核心群共有1 100余头,制冻精种公牛9头。辽育白牛共8个家系。外貌整齐,遗传性能稳定,具有生长快、产肉多、耐粗饲、繁殖力良好等优点。     

Plasma concentration of estrone sulfate during pregnancy in different breeds of Japanese beef cattle

Plasma concentrations of estrone sulfate in different breeds of Japanese beef cattle and the relationship between those concentrations and feto-placental growth were examined in order to assess the possibility of monitoring abnormal growth of the fetus. Blood samples were obtained from cows from day 90 of gestation to parturition. The plasma concentration of estrone sulfate was measured by direct enzyme immunoassay. From day 180 of gestation, the mean concentration of estrone sulfate increased gradually and it was drastically elevated after day 240 of gestation with the maximum at day 285. Plasma concentrations of estrone sulfate on day 240 of gestation was significantly increased in F(1) cows (Holstein Friesian and Japanese Black) compared with those in other breeds of cow. From day 270 to 278 of gestation, estrone sulfate concentrations of Holstein Friesian cows inseminated by Holstein Friesian differed from those inseminated by Japanese Black. In the cow with retained placenta, the plasma concentration of estrone sulfate reached plateau at day 240 of gestation and did not increase thereafter. There was no significant relationship between estrone sulfate concentration and duration of gestation, calf birth weight, weight of placenta or viability of newborn calves. These results indicate that changes of plasma estrone sulfate concentration in Japanese beef cattle are very similar to those in Holstein dairy cattle. They also suggest that the plasma concentration of estrone sulfate is associated with the breed of pregnant cow and that its concentration is also affected by calf birth weight depending on the breed of bull. It seems possible to predict the incidence of retained placenta but not the calf birth weight and viability of newborn calves in Japanese beef cattle.     

The Use of Beef Bull Semen Reduced the Risk of Abortion in Neospora‐seropositive Dairy Cows

There is an evidence that the epidemiology of neosporosis differs in dairy and beef cattle, such that beef cattle carry a lower risk of abortion. The aim of the present study was to establish whether artificial insemination using semen from beef bulls could reduce the risk of abortion in dairy cows seropositive for the Neospora caninum parasite. Our study was based on yearly serological screening for neosporosis and on the confirmation of Neospora infection in aborted fetuses in two high‐producing dairy herds with a mean 28% seroprevalence of N. caninum antibodies. The study population comprised of 273 pregnancies in seropositive animals: 156 pregnancies monitored after insemination using Holstein–Friesian semen and 117 after insemination using beef bull semen. Abortion rates for these animals were 28.2% (77 of 273), 34.6% (54 of 156) and 19.7% (23 of 117). Logistic regression analysis indicated no significant effects of lactation number and previous abortion on the abortion rate. Based on the odds ratio, a 1‐unit increase in the Neospora antibody titre yielded a 1.01‐fold increase in the abortion rate. The likelihood of abortion was two times higher for cows in one of the two herds and 2.8 times lower (one of 0.36) for pregnant cows inseminated with beef bull semen rather than Holstein–Friesian semen. Our results indicate that the use of beef bull semen can reduce the risk of abortion in dairy cows, and suggest that annual screening for neosporosis, specifically the antibody titre to the protozoan, could be an useful predictor of abortion risk in reproductive health programmes.     

Review: Cost of Reproductive Diseases and Conditions in Cattle

Based on information from USDA National Animal Health Reporting System early State pilot studies and more recent national studies, the cost of reproductive diseases and conditions was estimated for beef and dairy cattle. We estimate the total yearly cost of female infertility, abortions/stillbirths, dystocia, retained placentas, and metritis/pyometra to be $441 to $502 million for beef producers and $473 to $484 million for dairy producers with an aggregate national total of approximately $1 billion annually. This loss is over six times more costly than that resulting from respiratory diseases. Three-fourths of the cost for reproductive diseases and conditions can be attributed to female infertility and dystocia and the failure to produce a healthy calf that will survive the first 24 h of life. Aggregate national costs are roughly evenly divided between beef and dairy; per cow costs are more than three times greater for dairy cows ($52.60) than for beef cows ($14.00). Approximately equal national costs are attained because there are more than three times more beef cows than dairy cows. One factor contributing to the greater cost for dairy cows is lost milk production associated with dystocia and retained placentas. Lost milk production accounts for one-third of the costs associated with reproductive diseases and conditions in dairy cattle. We conclude from this review and our resulting estimates that focusing on developing strategies to increase the probability of conception, minimize dystocia, and produce a healthy calf that survives beyond the first 24 h of birth must continue to receive high priority in both dairy and beef cattle management and research.     

The use of beef bull semen reduced the risk of abortion in Neospora-seropositive dairy cows

There is an evidence that the epidemiology of neosporosis differs in dairy and beef cattle, such that beef cattle carry a lower risk of abortion. The aim of the present study was to establish whether artificial insemination using semen from beef bulls could reduce the risk of abortion in dairy cows seropositive for the Neospora caninum parasite. Our study was based on yearly serological screening for neosporosis and on the confirmation of Neospora infection in aborted fetuses in two high-producing dairy herds with a mean 28% seroprevalence of N. caninum antibodies. The study population comprised of 273 pregnancies in seropositive animals: 156 pregnancies monitored after insemination using Holstein-Friesian semen and 117 after insemination using beef bull semen. Abortion rates for these animals were 28.2% (77 of 273), 34.6% (54 of 156) and 19.7% (23 of 117). Logistic regression analysis indicated no significant effects of lactation number and previous abortion on the abortion rate. Based on the odds ratio, a 1-unit increase in the Neospora antibody titre yielded a 1.01-fold increase in the abortion rate. The likelihood of abortion was two times higher for cows in one of the two herds and 2.8 times lower (one of 0.36) for pregnant cows inseminated with beef bull semen rather than Holstein-Friesian semen. Our results indicate that the use of beef bull semen can reduce the risk of abortion in dairy cows, and suggest that annual screening for neosporosis, specifically the antibody titre to the protozoan, could be an useful predictor of abortion risk in reproductive health programmes.