Effects of an Estradiol Implant on Locoweed Consumption,Toxicity, and Recovery in Growing Beef Steers

Two experiments were conducted to determine effects of an estradiol implant (Compudose®) on locoweed consumption and toxicity in growing steers. In Exp. 1, 16 crossbred steers (185.3 ± 6.1 kg) were randomly assigned to two replicated treatments and received either an estradiol implant or no implant. Steers were assigned to one of four pastures and were rotated through all pastures, which differed in locoweed distribution, to allow equal access. Bite counts were recorded twice daily at 0600 and 1700 h during a period when steers were likely to consume locoweed. For bite counts, steers were observed for 5 min each, starting at 0600 and at 1700 h, and the number of bites taken of cool- and warm-season grasses, forbs, and locoweed were recorded. Blood was collected on d 0, 7, 28, 35, 63, and 119, and individual BW was recorded on d 0, 35, 63, and 119. Proportion of bites of locoweed consumed by implanted vs nonimplanted steers did not differ (P>0.10). Likewise, ADG, serum alkaline phosphatase activity, and thyroxine concentrations did not differ (P>0.10) between implanted and nonimplanted steers. In Exp. 2, 20 crossbred steers (212.3 ± 6.1 kg) were divided into four groups and individually fed in a 2 × 2 factorial arrangement of treatments. Treatments included: 1) estradiol implant + locoweed, 2) implant, no locoweed, 3) no implant + locoweed, and 4) no implant, no locoweed. Steers were implanted at d 0 and fed either a ground forage diet containing 80% sudangrass hay and 20% locoweed, or a diet of 100% sudangrass hay. Implanted steers had improved ADG vs nonimplanted steers (P<0.10) through 63 d on trial, but no differences were observed in steers fed locoweed vs sudangrass hay diets (P>0.90; locoweed x implant, P>0.10). Alkaline phosphatase activity was greater (P<0.05) for steers fed locoweed vs those not receiving locoweed on d 7, 14, and 21, whereas, thyroxine concentration was lower (P<0.06) in steers fed locoweed than those not fed locoweed on d 14 and 21. Estradiol concentrations were greater in implanted steers vs those not implanted (P<0.05). These results suggest no effect of an estrogen implant on locoweed consumption or on severity of locoweed toxicity by beef steers.     

应用夏洛莱、利木辛肉牛开展三元杂交效果试验

经过20年的努力，凉州区黄牛改良工作取得了显著的成效，黄牛冻配点由最初的10个发展到现在的145个，年授配母牛3万头。为建立适合凉州区的最佳肉牛生产模式，进一步提高该区肉牛生产水平，凉州区从1998年开始，引入夏洛莱、利木辛、德国黄牛、皮埃蒙特等著名肉牛品种与当地西杂母牛进行三元经济杂交，取得了较好的效果。我们于2000年9月20日至2001年1月6日，在凉州区新华乡开展了应用夏洛莱、利木辛肉牛分别与当地西杂牛三元杂交效果试验。现将结果报告如下。     

Maternal performance of Hereford, Brangus, and reciprocal crossbred cows under semidesert conditions.

Maternal performance of 134 Hereford (H), Brangus (B), and reciprocal crossbred (H x B and B x H) cows from 2 to 7 yr of age was evaluated under semidesert conditions in this study. Calves produced by 2- and 3-yr-old cows were sired by Brangus and Hereford bulls. Calves produced by 4- to 7-yr-old cows were sired by Charolais bulls. Breed of sire and breed of dam of cow affected kilograms of weaning weight, 205-d weight, weaning weight as a percentage of cow weight, and 205-d weight as a percentage of cow weight produced annually. Brangus (either as sire or dam of cow) was superior to Hereford in all cases. Observed maternal heterosis on 2- to 3-yr-old cows was 23.0, 20.1, 30.0, 29.1, 23.9, and 23.0% for calf birth date, weaning percentage, weaning weight per year, 205-d weight per year, weaning weight as a percentage of cow weight per year, and 205-d weight as a percentage of cow weight per year, respectively (P less than .01). Observed maternal heterosis from mature cows was 19.8, 12.8, 21.0, 18.7, 17.4, and 15.4% for calf birth date, weaning percentage, weaning weight per year, 205-d weight per year, weaning weight as a percentage of cow weight per year, and 205-d weight as a percentage of cow weight per year, respectively (P less than .01). Results indicate large heterotic effects on annual cow productivity and an adaptive advantage for cows with Brangus sires and(or) dams under semidesert conditions.     

夏海黄三元杂种牛生长发育研究

测定分析了夏海黄三元杂交后代（公牛３４头，母牛３７头）与豫北黄牛及海黄Ｆ１初生－２４月龄体尺与体重均较豫北黄牛有较大幅度提高，较海黄Ｆ１提高明显，利用夏海黄三元杂交发展肉牛生产是一条有效途径。     

Estimation of additive and nonadditive genetic variances in Hereford, Gelbvieh, and Charolais by Method R.

Parameters for direct and maternal dominance were estimated in models that included non-additive genetic effects. The analyses used weaning weight records adjusted for age of dam from populations of Canadian Hereford (n = 467,814), American Gelbvieh (n = 501,552), and American Charolais (n = 314,552). Method R estimates of direct additive genetic, maternal additive genetic, permanent maternal environment, direct dominance, and maternal dominance variances as a proportion of the total variance were 23, 12, 13, 19, and 14% in Hereford; 27, 7, 10, 18, and 2% in Gelbvieh; and 34, 15, 15, 23, and 2% in Charolais. The correlations between direct and maternal additive genetic effects were -0.30, -0.23, and -0.47 in Hereford, Gelbvieh, and Charolais, respectively. The correlations between direct and maternal dominance were -0.38, -0.02, and -0.04 in Hereford, Gelbvieh, and Charolais, respectively. Estimates of inbreeding depression were -0.20, -0.18, and -0.13 kg per 1% of inbreeding for Hereford, Gelbvieh, and Charolais, respectively. Estimates of the maternal inbreeding depression were -0.01, -0.02, and -0.02 kg, respectively. The high ratio of direct dominance to additive genetic variances provided some evidence that direct dominance effects should be considered in beef cattle evaluation. However, maternal dominance effects seemed to be important only for Hereford cattle.     

Estrogenic Properties of Locoweed (Astragalus lentiginosus)

Locoweed, Astragalus lentiginosus was extracted with ether (EE) and water (WE). These and the plant residue were mixed with basal diet (BD) and fed to weanling female mice to determine the plant's estrogenic activity. Diethylstilbesterol (DES) was fed as a control. Uterine weight was taken at five to seven days. Three feeding trials were conducted.

In Trial 1 one group of mice was fed a basal diet and one group the basal diet plus EE 1 gm/mouse. The uteri from mice receiving EE were heavier (P <.01) than from those receiving BD.

In Trial 2 mice were fed 0.10 gmEE/mouse, 0.15 gm EE/mouse, 0.10 and 0.15 µg DES/mouse and basal diet. The uteri from the DES fed mice were heavier (P <.01) than the others. The uteri from the EE mice and the BD mice were lighter than those of the DES mice, but there was no difference between the uteri from the EE and BD. This was thought to be due to the level of EE fed.

In Trial 3 three levels of EE, 1.30, 0.86, and 0.42 gm/mouse, two levels of DES, 0.075 and 0.150 µg/mouse, one level water extract, 3 gm/mouse, plant residue, 3 gm/mouse, and basal diet were fed. The uteri from EE mice were heavier (P <.01) than the DES and DES heavier (P <.01) than WE or BD fed mice. Lesions typical of locoweed poisoning were found in WE fed mice. It was concluded that locoweeds contain high levels of estrogenic compounds as well as those causing pathological lesions.

     

不同肉牛品种杂交组合肥育效果对比试验

[目的]为了观察不同品种杂交肉用牛的育肥效果.[方法]试验选择20月龄左右(体重300±20.5 kg)的西杂牛(西门塔尔♂×本地黄牛♀)、利杂牛(利木赞♂×本地黄牛♀)和本地黄牛各20头,以青贮玉米和苜蓿干草为基础粗饲料,经过90d的短期肥育,研究肉牛肥育效果与品种之间的关系,进而分析各项屠宰指标.[结果]表明:西杂...     

Effects of Tuli,Senepol, Brahman,Angus, and Polled Hereford Sire Breeds on Birth and Weaning Traits of Offspring

Progeny (n = 861) of tropically adapted breeds [Tuli (TU), Senepol (SE), and Brahman (BR)] and temperate breeds [Angus (AN) and Polled Hereford (HP)] were evaluated for birth and weaning traits in each of 5 yr. Multiparous crossbred cows representing three genetic types [British (Bt), ½BR½Bt, and ¾Bt¼BR] were mated to AN, HP, TU, SE, and BR sires, with the exception that BR sires were not mated to ½BR½Bt cows. Calving season was January through early March. Following calving, cows were provided bermudagrass hay and bahiagrass hay and had limited access to rye and ryegrass pastures. Cow and calf pairs grazed bermudagrass and bahiagrass pastures as available until weaning without access to creep feed. Male calves were castrated at birth and were not implanted. Data included birth weight, cannon bone length at birth, weaning weight, weaning hip height, ADG from birth to weaning (ADGBW), ADG from birth to April (ADGBA), ADG from April to weaning (ADGAW), and weight per day of age (WDA). Data were analyzed by PROC Mixed using a model that included calf genetic type, calf sex, calf birth day of year, and calf genetic type × calf sex interaction. Random effects were cow age, birth year, and sire and dam of calf. Calf genetic type and calf sex were significant sources of variation for all characteristics. Linear contrasts revealed that BR-sired calves were heavier at birth, had longer cannon bones at birth, and were taller at weaning (P<0.01). Tuli- and SE-sired calves were similar to AN- and HP-sired calves for birth weight, cannon bone length at birth, and weaning hip height. Angus-, HP-, and BR-sired calves were heavier at weaning compared with TU-sired calves, and SE-sired calves were intermediate for weaning weight (P<0.01). In conclusion, the TU-sired calves were smaller at birth and at weaning when compared with BR-sired calves. The TU- and SE-sired calves appear to offer more moderate size and growth rate through weaning than do the BR-sired calves.     

引进肉牛品种在中国的杂交应用研究进展

文章综述了近年来从国外引进的优良肉牛品种对本土牛杂交改良方面的研究应用情况,重点介绍了西门塔尔、安格斯、夏洛莱、利木赞等优良品种与本地牛的杂交后代在生长发育性能、产肉性能、繁殖性能、胴体品质、抗病性及经济效益等方面的表现,旨在总结中国肉牛的杂交改良工作,为进一步推动中国肉牛杂交改良体系的形成提供参考。     

采用红色肉牛改良早胜牛效果观察

引用国外著名的红色肉牛品种南德温、利木赞、德国黄牛和安格斯细管冻精杂交改良早胜牛。结果表明,均显示其父本的特征,被毛大多数为红色、紫红色和黄红色。初生至6月龄体重和相关的体斜长、胸围均优于早胜牛,也表现出了其杂交优势,其中南×早和利×早与德×早、安×早杂交群体相比,在生长发育过程中表现出更好的发育趋势,即南×早>利×早>德×早>安×早,且发现采用肉用型牛改良早胜牛,大型肉牛优于中型肉牛,中型肉牛优于小型肉牛的趋势。     

山东地方肉牛品种保护与开发现状、存在的问题及对策

山东是全国的养牛大省,拥有3个肉牛地方品种,多个国外引进品种,形成了肉牛生产3大片区,但是地方品种牛的保护与开发却存在着诸多问题,制约了全省肉牛业的发展。文章从五个方面提出了地方品种肉牛保护与开发的建议与对策,对改善当前的地方肉牛品种选育、保护与开发具有一定的现实意义。     

中国疯草防除与利用研究

中国疯草主要布在西南、西北和华北广大牧区，面积达400多万hm^2。多年来，疯草严重威胁着当地畜牧业的发展，造成重大的经济损失。本文从人工防除与利用，生物控制与灭除，化学控制与灭除和动物免疫预防及化学治疗四个方面就有关疯草防除和利用的技术和方法进行综述。     

青海高原地区良种肉牛改良当地黄牛的效果

在青海高原环境下,用引进的良种肉牛蓝白花、利木赞、西门塔尔和皮尔蒙特改良当地黄牛.结果显示四个杂交组合F1代不同年龄的生长速度和体尺指标均明显优于青海黄牛(P＜0.01),说明用良种肉牛改良青海黄牛效果明显;在不同杂交后代的比较中,皮×黄F1代各年龄段体重均高于蓝×黄F1、利×黄F1和西×黄F1(P＜0.01),皮×黄F1代还保留了青海黄牛抗逆性强,耐粗饲等优良特性,杂交组合较为理想;皮尔蒙特牛可作为当前高原环境下改良青海黄牛的理想父本品种使用.     

青海高原地区良种肉牛改良当地黄牛的效果

在青海高原环境下,用引进的良种肉牛蓝白花、利木赞、西门塔尔和皮尔蒙特改良当地黄牛。结果显示:四个杂交组合F1代不同年龄的生长速度和体尺指标均明显优于青海黄牛(P<0.01),说明用良种肉牛改良青海黄牛效果明显;在不同杂交后代的比较中,皮×黄F1代各年龄段体重均高于蓝×黄F1、利×黄F1和西×黄F1(P<0.01),皮×黄F1代还保留了青海黄牛抗逆性强,耐粗饲等优良特性,杂交组合较为理想;皮尔蒙特牛可作为当前高原环境下改良青海黄牛的理想父本品种使用。     

皮埃蒙特牛、夏洛来牛杂交改良南阳牛效果比较分析

本文主要介绍了皮埃蒙特牛、夏洛来牛杂交改良南阳牛方面的最新研究成果。测定了大量的皮南杂交牛、夏南杂交牛、南阳牛的体尺体重数据，并对3月龄、6月龄、12月龄各年龄段的体尺体重数据进行比较分析，发现用皮埃蒙特牛改良南阳牛的效果比夏洛来牛的改良效果好。     

不同品种牛背最长肌抗氧化性能的研究

本试验旨在研究不同品种牛肌肉的抗氧化特性,为优质牛肉的生产提供试验数据。选用5个品种牛(利木赞牛、中国西门塔尔牛、鲁西牛、秦川牛、晋南牛)的背最长肌,测定肌内脂肪含量、24小时的滴水损失以及在0～4℃下肉色、过氧化物值(PV)及硫代巴比妥酸反应物(TBARS)在72h内的变化动态。结果表明,背最长肌的肌内脂肪含量与24小时滴水损失率在不同品种牛肌肉之间没有显著差异(P>0.05);在整个储存时期(0～72h),5个品种牛肌肉的a*、b*值均呈下降趋势;4～72h内,利木赞牛肌肉的a*值均是最高的,且在冷藏8、12h时,利木赞牛肌肉的a*值显著大于鲁西牛肉和秦川牛(P<0.05),24h后利木赞牛的a*值显著大于西门塔尔牛(P<0.05);随着储存时间的延长,5个品种牛背最长肌的PV和TBARS值均有不同程度的增加,利木赞牛肌肉的PV和TBARS值增加最慢,秦川牛和鲁西牛肌肉的PV和TBARS值增加较快。结果表明,5个品种牛的肌内脂肪含量和滴水损失差异不显著,利木赞牛肌肉能够较长时间保持肉色和抗氧化特性。     

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。     

不同品种肉牛产肉性能、牛肉营养品质及风味物质的比较

本文旨在比较不同品种肉牛的产肉性能、牛肉营养品质及风味物质的差异。试验选取6月龄健康西杂牛、犏牛和宣汉黄牛去势公牛各6头,平均体重分别为(616.67±9.50)kg、(457.01±15.73)kg、(462.67±12.57)kg。所有试验牛均在相同饲养条件下人工育肥至30月龄。结果表明:1)西杂牛的胴体长、胴体深、胴体胸深、后腿长、后退宽和后腿围均显著高于犏牛和宣汉黄牛(P<0.05),西杂牛的腰部肉厚、肋部肉厚和大腿肉厚显著高于犏牛(P<0.05)。2)西杂牛的金钱展、前腱子、上脑、外脊、里脊、大黄瓜条、小黄瓜条、霖肉和臀肉的产量都显著高于犏牛和宣汉黄牛(P<0.05)。犏牛的辣椒条和眼肉产量占胴体重比显著高于西杂牛(P<0.05),宣汉黄牛的上脑、眼肉和外脊产量占胴体重比显著高于西杂牛(P<0.05)。3)西杂牛背最长肌中钙、磷、钠、钾和镁含量均显著高于犏牛和宣汉黄牛(P<0.05)。4)犏牛背最长肌中的总氨基酸、必需氨基酸含量以及必需氨基酸/总氨基酸、必需氨基酸/非必需氨基酸均显著高于西杂牛和宣汉黄牛(P<0.05),犏牛背最长肌中的鲜味氨基酸和甜味氨基酸含量显著高于西杂牛(P<0.05),犏牛的背最长肌氨基酸评分也要优于西杂牛和宣汉黄牛。5)犏牛背最长肌中的谷氨酸钠含量显著高于西杂牛(P<0.05),犏牛背最长肌中硫胺素和肌苷含量均显著高于宣汉黄牛和西杂牛(P<0.05)。综上所述,西杂牛的产肉性能和肉中矿物质含量要高于犏牛和宣汉黄牛,犏牛肉的氨基酸组成和评分以及风物物质含量要优于西杂牛和宣汉黄牛。     

Influence of breed and diet on growth, nutrient digestibility, body composition and plasma hormones of Brangus and Angus steers

Two split-plot designed experiments were conducted to determine the effects of breed (Angus, A, or Brangus, B) and diet (fescue hay, FH; corn silage, CS; or concentrate) on composition and rate of growth, diet digestibility and plasma hormones of steers. In Exp. 1, 10 steers (five of each breed) were fed a CS-based diet followed by a FH-based diet for two consecutive 60-d periods. Both breeds had lower (P less than .01) DM intake and digestibility when fed FH than when fed CS diets. The B steers had higher (P less than .01) plasma insulin concentrations than A steers when fed the CS diet. In Exp. 2, during two consecutive years, 10 steers previously fed CS- and FH-based diets were finished with a corn silage-whole shelled corn-based diet. During yr 1, A steers had higher (P less than .01) DM intake and plasma triiodothyronine (T3) and thyroxine (T4) concentrations (P less than .05) than B steers did. Although final weights were similar (P greater than .10), A steers had heavier (P less than .05) carcass weights than B steers did. During yr 2, A steers had higher (P less than .07) DM and starch digestibilities and higher (P less than .01) plasma T4 concentrations than B steers did. The greater (P less than .01) energetic efficiency of A steers was attributed to the greater rates of fat deposition during yr 2. Regardless of type of diet fed, A steers were more efficient at depositing energy. Higher circulating T4 concentrations of A than B steers may explain some of the physiological differences between these breeds.