早期断奶后备母牛繁殖效果研究

选择后备母牛１８头，每组各６头，采用不同的日粮饲喂，进行对照试验，结果试验１组后备母牛初情月龄平均为１０．３个月，第一、二情期受胎率８３．３％，繁殖成活率８３．３％。试验２组后备母牛初情期平均为１１．１个月，第一、二情期受胎率６６．７％，繁殖成活率６６．７％。对照组后备母牛初情期平均为１２．７个月，一、二情期受胎率５０．０％，繁殖成活率５０．０％。     

HMG和FSH用于安格斯牛超数排卵的效果比较

超数排卵在动物胚胎工程技术的体内胚生产中起关键作用,不同品种甚至个体对超数排卵的反应不同。人绝经期促性腺激素(HMG)是从绝经期妇女尿液中提纯得到的具有促卵泡素(FSH)活性的蛋白质激素,在医学上广泛应用于诱导排卵和治疗不育不孕症。本试验以安格斯青年母牛为超排供体,采用分次肌肉注射激素方法进行超排处理,比较了HMG与FSH用于安格斯母牛超数排卵的效果。B超检查发现,HMG和FSH超排处理后牛只两侧卵巢上直径>1cm的卵泡数分别为10.33±0.52和9.25±0.46个,二者差异不显著(P>0.05),表明HMG与FSH同样安全有效;总剂量1 400IU的HMG或FSH用于安格斯母牛超排后B超检查卵巢没有发现异常变化,说明该剂量是用于安格斯母牛超数排卵的安全有效剂量。     

应用体尺指标估测西杂后备母牛体重

通过测定张掖市甘州区甘浚镇120头西门塔尔杂交后备母牛的体高、胸围、体斜长和实际体重,发现后备母牛生长符合母牛育成期的生长规律,可以用公式来估测后备母牛的体重,用约翰逊公式和体重估测系数估测体重误差率均在5％以下。     

中国规模化牧场后备奶牛疾病与淘汰现状

后备奶牛健康生长对其未来生产性能具有重要影响.调研结果表明,呼吸系统疾病和营养代谢疾病是导致后备奶牛发病的主要原因,占比分别为46.0％和38.4％.而后备奶牛中发病最多的为哺乳犊牛,占比达51.4％.目前,哺乳犊牛发病率正在逐年降低,从2015年的43.3％降至2019年的25.4％.此外调研发现,造成后备奶牛被动淘...     

Use of Serum Protein Concentration to Predict Mortality in Mixed-Source Dairy Replacement Heifers

The relationship between serum protein concentration in the 1st week of life and survival to 16 weeks of age was examined in 3,479 Holstein replacement heifers over a period of 10 years on a farm with endemic salmonellosis. Thirty-four percent of calves studied had serum protein concentrations <5.0 g/dL and 60.5% of calves had serum protein concentrations <5.5 g/dL. Cumulative mortality was 7.9%, indicating that calves with marginal passive transfer status can be reared successfully under conditions of endemic salmonellosis. Optimal survival was observed in calves with serum protein concentrations >5.5 g/dL. Calves with serum protein concentrations of 5.0–5.4 g/dL had only a slightly increased relative risk (RR) of mortality (RR = 1.3) compared to calves with serum protein concentrations >5.5 g/dL. The highest RR was experienced by calves with serum protein concentrations <4 g/dL (RR = 4.6) and 4.0–4.4 g/dL (RR = 3.1). Calves with inadequate passive transfer (serum protein concentration <5.0 g/dL), experienced increased mortality until at least 10 weeks of age, indicating that failure of passive transfer has an effect on calf health that extends into the juvenile period. Models in which serum protein concentration was treated either as a continuous variable or as a categorical variable failed to demonstrate any significant interaction between baseline mortality and the RR of mortality. This finding suggests that the RR derived in the present study should be applicable to farms with dramatically different baseline mortality rates.     

新疆天山某安格斯牛场安格斯牛生长发育规律分析

为研究安格斯牛各体尺指标及体重间的相关关系,掌握其生长发育规律,试验采集了新疆天山某安格斯牛场出生于2012-2016年的安格斯牛生长发育记录,共649条,其中主要包括体重及体尺指标,应用SPSS 16.0软件分析安格斯牛主要体尺指标及体重的相关性。结果发现：安格斯牛体尺指标及体重均随着月龄的增加逐步增大;14月龄之前各体尺指标增长速度较快,14月龄以后增长速度的缓;腹围和胸围增长速度高于其他指标。安格斯公牛的体长指数、体躯指数、胸围指数和管围指数平均分别为111.99%、129.79%、145.26%和16.71%;母牛体长指数、体躯指数、胸围指数和管围指数平均分别为112.15%、132.01%、147.86%和16.95%。安格斯牛体重与体高、体长、胸围、腹围和管围的相关性均达到极显著水平（P<0.01）;各体尺指标两两均呈极显著正相关（P<0.01）,其中,胸围与腹围的相关性最高,公、母牛相关系数分别为0.948、0.939;腹围与管围之间的相关性最低,相关系数分别为0.797和0.851。本试验结果可为明确安格斯牛选育方向,开展其遗传育种、品种资源开发利用提供基础数据。     

Factors Affecting the Readiness and Preparation of Replacement Heifers in Tropical Breeding Environments

The future of beef cattle production in tropical regions is uncertain because of land tenure concerns, threatening the survival of extensive management programmes in these areas of the world. The need to intensify production systems will inevitably lead to changes in the management of replacement animals in existing herds. The present review underlines the main constraints, which in the past could be resolved by the sheer numbers of animals present in beef cattle operations, with replacements reliant only on finding enough heifers to substitute the adult females destined for culling. This scenario is rapidly changing as beef cattle units in tropical regions subdivide to share out the land between as many farmers as possible. Consequently, issues such as the efforts needed to manage the pregnant cow, particularly her nutritional status and its effect on the new‐born calf, the future replacement heifer growing in the presence of the dam, weaning management and procedures required before a heifer can be introduced into a breeding programme, need to be adequately and efficiently addressed by farmers in tropical regions.     

BVDV对后备牛生长发育状况及繁殖性能的影响

牛病毒性腹泻/黏膜病(BVD/MD)是一种严重危害奶牛健康的病毒性传染病,其病原为牛病毒性腹泻病毒(BVDV)。BVDV感染牛后主要表现两种状态,即一过性感染(TI)和持续性感染(PI)。BVD在牛场的流行,可严重影响奶牛的生产性能、繁殖性能及牛群健康状况,对奶牛的影响可表现为流产、胎儿畸形、腹泻和免疫抑制等。怀孕母牛在特定妊娠阶段感染BVDV后,可娩出PI犊牛,部分PI犊牛能像正常犊牛一样生长发育至成年,但其生长发育状况和繁殖性能较同龄健康牛差异十分明显。为评价BVDV对后备牛生长发育及繁殖状况的影响,笔者采用ELISA方法检出北京地区28个规模化奶牛场141头BVDV-PI牛,并与同龄健康牛生长发育及繁殖数据相比较,结果表明,BVDV-PI后备牛各月龄段的体高、体重均低于健康后备牛,其首次输精日龄、配准日龄、耗精量明显高于健康后备牛,而一次情期受胎率显著低于健康后备牛。数据显示,BVDV严重影响后备牛的生长发育及繁殖状况。     

安格斯杂种后代生长曲线拟合分析

位于三峡库区的川南山地黄牛具有体型较小、体躯紧凑结实、性情温驯、行动轻快、役力强等特点,但其产肉性能差,难以满足市场对牛肉的需求。为此引入了黑安格斯和红安格斯分别与其杂交,杂种后代生长发育较好。为了进一步探讨其生长过程,正确认识其遗传特性和生长规律,为杂交组合     

饲粮磷水平对西门塔尔杂交后备母牛营养物质表观消化率的影响

本文旨在研究饲粮磷(phosphorus,P)水平对后备母牛营养物质表观消化率的影响.选用体况良好、体重(369.5±37.8)kg的杂交后备母牛[西门塔尔牛(♂)×中国黄牛(♀)]24头,随机分为6组,每组4头,定量(3.50 kg/d)饲喂6种不同磷水平的精饲料,粗饲料(玉米青贮)自由采食.各试验组精饲料磷水平分别...     

CPM模型优化饲粮对16～24月龄后备荷斯坦母牛生长发育和血清生化指标的影响

本文旨在研究应用CPM模型优化规模化奶牛场16~24月龄后备母牛饲粮对该阶段母牛生长发育及血清生化指标的影响。选择体重和体高相近的相同月龄(16月龄)荷斯坦后备母牛40头,将试验奶牛随机分为对照组和试验组,每组各20头,对照组后备母牛饲喂牛场当前饲粮,试验组后备母牛饲喂CPM模型优化后的饲粮,试验期从16月龄开始止于24月龄,共270d。结果表明:饲喂经CPM模型优化的饲粮显著提高了17月龄后备母牛的管围(P0.05);试验组后备母牛的管围指数在17、18、20、21、23和24月龄时显著高于对照组(P0.05),胸围指数在17和18月龄时显著高于对照组(P0.05)。试验组后备母牛血清中钙的含量在17、23、24月龄时显著高于对照组(P0.05),血清中磷的含量在16月龄时极显著地高于对照组(P0.01)。经CPM模型优化后,16~22月龄和23~24月龄的饲粮成本分别降低了1.03、0.32元/d。饲喂CPM模型优化的饲粮在一定的范围内促进了后备母牛的生长发育,同时降低了饲养成本。因此,CPM模型可用于16~24月龄荷斯坦后备母牛饲粮配方的评价和优化。     

安格斯牛在大通地区生长发育观测初报

以当地黄牛为对照,对胚胎移植后所产的18头(♀8,♂10)安格斯牛在大通县的生长发育情况进行分析。结果表明,初生公犊为29．12 kg,母犊为25．42 kg。3月龄、6月龄、12月龄公犊平均体重分别为108．57 kg、183．59 kg和322．8 kg,比青海黄牛公牛相应月龄分别提高55．2％、67．7％和81．2%;母犊平均体重分别为102．61 kg、171．33 kg和301．61 kg,比青海黄牛牛相应月龄分别提高38．1％、68．4％和79．9％;而且,安格斯牛的体型外貌、体尺均比青海黄牛有明显提高,表现出良好的肉用牛特征。     

CPM模型优化饲粮对7～15月龄后备荷斯坦母牛生长发育和血液生化指标影响

本文利用CPM模型优化规模化奶牛场7~15月龄后备母牛饲粮,研究优化后饲粮对后备母牛生长发育和血液生化指标的影响。选用相同月龄(7月龄),胎次、体高和体重相近的健康后备荷斯坦母牛40头,按照配对试验设计把试验奶牛随机分为2组,每组20头,对照组采用奶牛场现有的饲粮配方,试验组采用CPM模型优化后的饲粮配方。试验期为270 d。结果表明:饲喂CPM模型优化饲粮极显著提高了后备母牛8、10、11、13和15月龄的管围(P<0.01);试验组后备母牛血清中钙含量在8月龄时显著高于对照组(P<0.05);优化后7月龄、8~9月龄、10~12月龄、13~15月龄饲粮成本比调整前分别降低了1.02、0.78、0.62和0.52元/(头·d)。由此可见,饲喂CPM模型优化饲粮可提高后备母牛的管围,促进后备母牛的生长,促进血钙的吸收,降低饲养成本,CPM模型可用于评价和优化后备荷斯坦母牛的饲粮配方。     

The Effect of Bovine Growth Hormone on Growth,Carcass Composition and Meat Quality of Dairy Heifers

Abstract

Our objective was to examine the effects of bovine growth hormone (bGH) on growth, carcass composition and meat quality of dairy heifers. Nine monozygotic twin pairs of Friesian or Red Danish cattle were used, and pair-fed à diet consisting of grass silage, barley and soybean meal. Within each pair, one animal was given daily subcutaneous injections of 20 IU of pituitary-derived bGH (15–20 mg), while the other animal was injected with saline (excipient). Treatments started at 179±2 kg body weight and lasted for 15.6 weeks. At slaughter, carcass composition and meat quality were analyzed. bGH treatment increased gain by 8% (948 vs. 877 g/d; P <0.03). The amount of saleable meat in carcass and lean content of four main carcass cuts were on average increased by 2% (P <0.05). Concomitantly, carcass fat trim was reduced by 12% (P <0.001), fat trim of individual cuts by 4–21% (P <0.05), and kidney fat by 13% (P <0.01). Except for a 20% reduction of intramuscular fat content (P <0.001), meat quality assessed by objective as well as subjective methods was unaffected by bGH treatment. In summary, bGH treatment of dairy heifers around puberty stimulated growth and reduced carcass fattening including intramuscular fat, while eating quality of the meat was unaffected.     

Feeding Strategies for Rearing Replacement Heifers in Small-scale Dairy Production Systems in the Highlands of Central Mexico

The growth of Holstein heifers in the campesino dairy systems in the highlands of Mexico was evaluated in three feeding strategies. Thirty-three heifers from 11 farmers, grouped according to strategy, were weighed every 14 days for 28 weeks. The live weight change over each 14-day period was estimated by individually regressing live weight over period, taking the regression coefficient as an unbiased estimate of live weight change. Regression coefficients were analysed as a randomized design with feeding strategies as treatments. Strategies were as follows: S1: grazed or cut pasture all year, maize silage and maize straw in the dry season, and 1.0–1.5 kg concentrate/heifer per day. S2: maize straw in the dry season, cut pasture forage, grazing of native grass, weeds from maize fields, and 1.0–1.5 kg concentrate/heifer per day. S3: maize straw in the dry season, grazed native grasses and weeds in the rainy season. Live weight gains were: S1, 0.511 kg/heifer per day; S2, 0.271 kg/heifer per day; and S3, 0.252 kg/heifer per day. Despite the better gains in S1, they are 24% below recommendations, arriving to service at 20 months of age. Not rearing their replacements may be a better alternative for campesino farmers under current economic conditions.     

西门塔尔杂交后备母牛日粮植物源磷进食量对表观可消化磷的影响

旨在采用消化试验研究后备母牛日粮植物源磷进食量与磷表观消化率的关系。试验选用体况良好、体重一致的西杂后备母牛[西门塔尔牛(♂)×中国黄牛(♀)]24头,随机分为6组,即试验1组、2组、3组、4组、5组和6组,每组4头,分别定量(3.50kg/d)饲喂6种不同磷水平的精料日粮,粗料(青贮)自由采食。使用麸皮调节日粮精料磷水平,各试验组精料磷水平分别为0.36%、0.40%、0.42%、0.46%、0.50%和0.54%;总试验期为30d,预饲期20d后进入正试期,试验最后7d全收集粪样和尿样。饲料样及粪样均测定其中磷和干物质含量,计算粪磷排泄量与日粮磷进食量的回归关系。结果表明,不同日粮处理间消化道磷的表观消化量和表观消化率有显著差异(P<0.05),并随进食磷量的增加而增加,但消化道表观消化的磷量与磷的进食不是直线关系,而是呈现抛物线关系,在日粮磷水平为0.42%时,消化量和消化率达最大,即分别为10.5g/d和40.8%。     

杏鲍菇菌糠对荷斯坦牛生长性能和经济效益的影响

[目的]为研究杏鲍菇菌糠对9～12月龄生长期荷斯坦奶牛生长性能和经济效益的影响。[方法]选择9～12月龄生长期荷斯坦奶牛60头,随机分为2组,分别饲喂原日粮和添加杏鲍菇菌糠全混合日粮,试验期60 d,分别测定采食量、日增重、体高、体长等生长指标,并分析经济效益。[结果]结果表明,菌糠饲料适口性好,试验组采食正常,两组间采食量无显著差异(P0.05);生长性能指标间无显著差异(P0.05);试验组饲料成本较对照组减少5.87元/(头·d)。[结论]杏鲍菇菌糠替代部分粗饲料饲喂9～12月龄生长期荷斯坦牛对其生长性能无影响,且显著降低饲料成本,具有现实推广价值。     

Estrous Characteristics and Pregnancy Rates of Beef Heifers Administered Two Synchronization Protocols,

Two estrous synchronization protocols were used to determine their effect on estrous characteristics, synchronization rates, and pregnancy rates in nulliparous beef heifers on a commercial cow-calf operation in western New Mexico. Fifty-three Red Angus and Angus × Hereford heifers were sorted by age and BW to compare heifers treated with gonadotropin-releasing hormone (GnRH) 7 d before treatment with prostaglandin F_2α [PGF_2α; SelectSynch (SS); n = 26] and heifers treated with two administrations of PGF_2α 14 d apart [Targeted Breeding™ (TB) (Pharmacia, Kalamazoo, MI); n = 27). An androgenized cow fitted with a chin-ball marker was placed in each pen of heifers, and a HeatWatch (HW) transmitter (DDx, Inc., Denver, CO) was attached to each heifer to monitor estrous characteristics. Heifers were artificially inseminated after estrus was determined by HW. Number of standing events tended (P=0.12) to increase for TB heifers compared with SS heifers (54.4 ± 7.4 and 37.5 ± 7.7, respectively). Duration of estrus was increased (P<0.05) in TB heifers (16.0 ± 1.3 h) compared with SS heifers (11.6 ± 1.3 h). However, overall synchronization and pregnancy rates were similar (P>0.10) between protocols. Androgenized cows identified 53% of the estruses detected by HW. When utilizing synchronization protocols, radiotelemetric estrous detection systems may identify more heifers in estrus than androgenized cows. Intensity of estrus was increased in TB heifers compared with SS heifers; however, synchronization and pregnancy rates were not influenced by synchronization protocol.