1／4野血牦牛,1／2野血牦牛及家牦牛初产产乳性能测定

对１／４野血牦牛、１／２野血牦牛和家牦牛的初产牛进行１２０天的产奶量和乳脂率测定。结果：日均挤乳量,１／４野血牦牛为０．９４±０．２２ｋｇ,１／２野血牦牛为１．０５±０．１８ｋｇ,家牦牛为０．１１±０．１０ｋｇ;乳脂率,１／４野血牦牛为６．２９％,１／２野血牦牛为５．６％,家牦牛为６．２４％。经ｑ检验,３组的日均挤乳量和１／４野血牦牛与家牦牛的乳脂率均差异不显著（Ｐ＞０．０５）,而１／２野血牦牛因野性较大,难以挤净含脂较高的二奶,以致乳脂率低于其它两组。     

含野血牦犊牛,家牦犊牛增重效果观察

１９９４－１９９６年在海南州赛什牧场对采用野牦牛冻精人工授精和１／２野血公牛本交两种方法配家牦母牛产生的１／２野血牦犊牛３５头和１／４野血牦犊牛４８头，跟踪定量观测。结果：１／２野血牦犊牛和１／４野血牦犊牛的平均初生重分别比家牦犊提高了７．６５％，８．８６％，平均１８月龄重分别比家牦犊牛提高４７．１６％，１７．２２％。     

对1／2和1／4野血牦犊牛生长发育的观测

１９９４～１９９６年在海南州赛什塘牧场对１／２和１／４野血牦犊牛的生长发育进行了观测。结果：１／２和１／４野血牦犊牛的初生重分别比家牦犊牛提高７．６５％和８．８６％（Ｐ＜０．０１），１／２野血牦犊牛在初生时的体高、体长和胸围比家牦犊牛分别提高３．２１％，５．５７％，５．５１％；６月龄时分别提高９．５６％，１１．４６％，３．５９％；１８月龄时分别提高９．１８％，１７．５５％，７．６４％（Ｐ＜０．０１）。     

野牦公牛的采精量及影响因素的研究

为了发挥野牦公牛在复壮家牦牛中的作用，笔者于１９９２￣１９９５年对４头野牦公牛和８头１／２野血牦公牛的采精量及影响因素进行了观测研究。对４年的观测资料分析结果表明：野牦公牛（包括１／２野血牦公牛）平均每次采精量为２．９２ｍｌ；７岁龄１／２野血牦公牛采精量最高，平均为３．７８ｍｌ；１１月份、每日下午和每日第１次采精时的采精量最高，分别平均为４．２２、３．７１和２．９８ｍｌ，应予重视和利用；野牦公牛的     

1/2野血牦公牛与家牦牛合群的调教

１／２野血牦公牛与家牦牛合群的调教鲍守刚（青海省畜牧兽医总站，西宁，８１０００１）１９９２年，我们曾在海晏县牧场投放９头３岁的１／２野血牦公牛，其目的是使１／２野血牦公牛和当地牦母牛本交生产１／４野血牦牛后代，观察推广效果。在投放期间当地牧工反映，１...     

家牦牛、半血野牦牛产奶性能分析

对２２头家牦牛、半血野牦牛的产奶量进行了测定。测定结果：经产家牦牛日挤乳量为１．３０±０．１４ｋｇ，初产家牦牛为１．１１±０．１０ｋｇ，半血野牦牛相应为１．２４±０．２４ｋｇ、１．０５±０，１８ｋｇ，乳脂率含量，经产家牦牛为６．４４±０．３４％，初产家牦牛为６．２４±０．３４％，半血野牦牛相应为６．２５±０．７３％，５．５１±０．６１％。     

大通家牦牛及含野血牦牛血清运铁蛋白多态性的比较研究

采用聚丙烯酰胺凝胶电泳法对大通家牦牛，１／２野血牦牛及１／４野血牦牛的血清运铁蛋白多态性进行了研究。结果发现：１．大通家牦牛，１／４野血牦牛的血清运铁蛋白位点有ＴＦＡＤ和ＴＦＤＤ两种基因表型，以ＴＦＤＤ为优质基因型，ＴＦ＾Ａ和ＴＦ＾Ｄ的基因频率分别为０．００４４和０．００９１及０．９９５６和０．９９０９；２．１／２野血牦牛血清运铁蛋白位点呈现单一的ＴＦＤＤ；３．大通家牦牛，１／４野血牦牛和１／２野     

果洛家牦牛产乳性能测定

对果洛州玛沁县雪山乡 10头经产、初产家牦母牛一个夏季的挤乳量进行了测定。测定结果 :经产母牛平均日挤乳量 1.0 6± 0 .16kg ,初产母牛为 0 .67± 0 .0 9kg ,经产母牛显著高于初产母牛 (P <0 .0 5 )。乳脂率含量经产母牛为6.5 7%± 0 .2 3 %,初产母牛为 6.69%± 0 .15 %,差异不显著 (P >0 .0 5 )     

大通家牦牛和含野血牦牛红细胞钾型的研究

采用火焰光度法对１０９头大通家牦牛，１１０头１／４野血牦牛和９３头１／２野血牦牛的红细胞四型进行了研究，结果表明：（１）大通家牦牛，１／４和１／２野血牺牦牛都有ＨＫ和ＬＫ两种表型，以ＨＫ型为优势表型；（２）３个牦牛群体Ｋ和Ｋ基因频率分别为０．０５１８，０．０５１３，０．０５５３和０．９４８２，０．９４８７，０．９４４７；（３）３个群体的基因分化系数为０．０００５０，表明导入野牦牛血对大通牦牛红细胞     

家牦牛,半血野牦牛年产毛量的比较

对１７６头各龄家牦牛和半血野牦牛的年产毛量进行了测定。测定结果：家牦牛１岁０．９８±０．２９ｋｇ／头，２岁１．１２±０．２２ｋｇ／头，３一５岁１．１８±０．３８ｋｇ／头，６岁以上０．８８±０．２７ｋｇ／头；半血野牦牛相应为０．９０±０．２０ｋｇ／头，１．０５±０．２７ｋｇ／头，０．６８±０．２８ｋｇ／头，０．９０±０．３８ｋｇ／头；３一５岁家牦牛组的年产毛量极显著高于６岁以上年龄组（Ｐ＜０．０１），同１岁、２岁年龄组的年产毛量差异不显著（Ｐ＞０．０５），２岁与６岁以上年龄组之间呈显著性差异（Ｐ＜０．０５）；半血野牦牛各年龄组的年产毛量差异不显著（Ｐ＞０．０５）；１岁家牦牛公母间，２岁半血野牦牛公母间，年产毛量差异极显著（Ｐ＜０．０１）。     

牦牛的泌乳性能及提高产奶量的途径

分布于红原及其毗邻地区的牦牛具有较优良的产奶性能和乳质特性。该地区牦牛184天产奶量为211 30kg;乳脂率6 82%,乳蛋白5 60%,乳糖5 20%,均高于黑白花奶牛。暖季适当补饲可提高泌乳黑犏牛日产奶量0 77kg;冷季半舍饲+补饲可使泌乳黑犏牛全泌乳期产量平均提高1096kg,延长泌乳期109～137天。畜群结构调控和常规繁殖技术,可显著提高适龄母牛的群体比率和繁殖率,从而提高群体产奶水平。应用现代生物技术,有望解决牦牛种间杂交过程中存在的一些问题,如提高改良犏牛的繁殖成活率,扩大改良规模、实现改良犏牛繁殖改良犏牛等,可提高牦牛改良的经济效益。     

新疆帕米尔牦牛生产性能的试验研究

[目的]为了探讨新疆帕米尔牦牛的生长发育、繁育性能及泌乳性能等特性。[方法]选取新疆帕米尔母牦牛50 头,通过非配对法人工受孕,检测母牛受配率和受胎率等繁育性能指标,记录产奶量、乳脂指标等评价泌乳性能,并在犊牛初生后分别于第0、1、3、6、12、18及24月龄时测量体重、体尺、体斜长等生长指标。[结果]18月龄新疆帕米尔牦牛的体重达343 kg,显著高于同时期的其他市售牦牛,证明新疆帕米尔牦牛的生长性能良好;繁殖率在75%以上,受胎率在90%以上,发情期集中在8月,繁殖成活率在90%以上,犊牛断奶成活率高达98%,证明新疆帕米尔牦牛具有良好的繁育性能;牛乳的乳脂率和乳蛋白率都达到生乳食品安全国家标准,产奶量也属于同类中的偏上水平,表明新疆帕米尔牦牛具有优良的泌乳性能。[结论]新疆帕米尔牦牛具有生长发育快、生产性能好、经济价值高等优势,是一种乳肉役兼用型的地方优良牦牛品种。     

影响荷斯坦牛产奶量差的因素分析

产奶量差是奶牛个体同一胎次前后2个泌乳月产奶量的差值,可准确反映产奶量变化情况。为探究影响荷斯坦牛产奶量差的因素,本研究收集整理了江苏省某大型奶牛场2015-2018年55 193头次荷斯坦牛生产性能测定记录,并利用最小二乘法分析胎次、测定年度、产犊季节、泌乳月4个因素对荷斯坦牛产奶量差的影响。结果显示:胎次、测定年度、产犊季节、泌乳月及其交互作用对产奶量和产奶量差均有极显著影响(P<0.01)。其中,不同胎次、测定年度和产犊季节的荷斯坦牛总产奶量在第2个泌乳月增加最快,产奶量差为8.79kg;头胎第6泌乳月、二胎第7泌乳月和三胎及以上第6泌乳月产奶量下降最大,产奶量差分别为-2.86kg、-4.59kg和-6.13kg;2015-2018年4个测定年度中,第10、第6、第7、第6泌乳月产奶量降低最大,产奶量差分别为-2.26kg、-4.98kg、-4.44kg和-3.56kg;春季产犊的荷斯坦牛第4泌乳月、夏季产犊的荷斯坦牛第12泌乳月、秋季产犊的荷斯坦牛第9泌乳月、冬季产犊的荷斯坦牛第6或第7泌乳月产奶量下降最大,产奶量差分别是-4.34kg、-4.71kg、-5.36kg和-5.40kg。此外,产奶量差与泌乳持续力呈极显著正相关(P<0.01),与产犊间隔呈显著正相关(P<0.05),与泌乳天数、高峰奶、乳脂率、蛋白率、305d产奶量呈极显著负相关(P<0.01)。因此,产奶量差作为衡量奶牛产奶量变化的指标之一,可为牧场进行科学饲养管理提供参考。     

Effect of Mycobacterium paratuberculosis infection on production, reproduction, and health traits in US Holsteins

Our objective was to estimate the effect of Mycobacterium paratuberculosis infection on milk, fat, and protein yield deviations, pregnancy rate, lactation somatic cell score, and projected total months in milk (productive life). A serum ELISA and fecal culture for M. paratuberculosis were performed on 4375 Holsteins in 232 DHIA herds throughout the US. Primarily first through third lactation cows (99% of total) were assayed for infection. Trait information (except productive life) was obtained for the lactation concurrent with disease tests. Productive life was total months in milk through a cow's life, which was projected if a cow was still milking. For most analyses, case definition for M. paratuberculosis infection was defined as either an ELISA S/P ratio>or=0.25 or a positive fecal culture for M. paratuberculosis or both. To determine if diagnostic test affected estimates, case definition was redefined to include only cows with ELISA S/P ratios>or=0.25 or only fecal culture-positive cows. Linear models were used to estimate effect of M. paratuberculosis infection on traits. M. paratuberculosis-infected cows (7.89% of cows) produced 303.9 kg less milk/lactation, 11.46 kg less fat/lactation, and 9.49 kg less protein/lactation (P相似文献   

中国荷斯坦奶牛RPL23A、ACACB基因3个SNPs检测及其与产奶性状的关联分析

旨在开展奶牛群体高乳成分功能基因的验证与筛选,利用微流控芯片自主选育技术分析北京地区母牛群体高乳蛋白、高乳脂基因频率,同时分析基因多态性及其与产奶性状的相关性。本研究对北京地区8个大型奶牛场1 596头中国荷斯坦奶牛RPL23A、ACACB基因的多态性进行了检测,所有个体均为3胎以内的泌乳牛,收集每头牛所有测定日的产奶量、乳脂率、乳蛋白率等数据,同时对3个多态位点不同基因型与产奶性状进行了关联分析。RPL23A基因的SNP位点g.20146771G>A,在第一泌乳期,与产奶量、乳脂量、乳脂率和乳蛋白量均达到极显著关联（P<0.01）,第二泌乳期,g.20146771G>A与5个产奶性状均呈极显著关联（P<0.01）。ACACB基因的SNP位点g.63962768C>T,在第一泌乳期,与产奶量、乳脂量、乳脂率和乳蛋白量均呈极显著关联（P<0.01）,在第二泌乳期,与产奶量、乳脂量、乳脂率和乳蛋白率呈极显著关联（P<0.01）。结果表明,RPL23A、ACACB基因可以作为影响中国荷斯坦奶牛产奶性状的候选基因用于标记辅助选择,以上基因位点可能通过直接或间接的途径影响奶牛的乳脂或乳蛋白性状,对产奶性状起到重要调控作用。本研究为荷斯坦奶牛后续的标记辅助选择奠定了良好基础。     

Effects of clinical mastitis on reproductive and milk performance of Holstein cows in Morocco

The aim of this study was to determine the influence of clinical mastitis and time of first mastitis occurrence on reproductive and milk performance of Holstein cows. Data were collected in a dairy farm from 2008 to 2012 on 1725 cows, among which 464 cows with mastitis. To determine the influence of clinical mastitis on reproductive and milk performance, models included fixed effects of parity, calving season, calving year, and group (cows with and with no mastitis). To determine the effect of time of 1st mastitis occurrence on reproductive performance, the mastitic cows group was further reclassified into three groups: prior to 60 days, between 60 and 90 days and greater than 90 days postpartum. For milk performance, the mastitic cows group was divided into two groups: before and after peak milk yield. Clinical mastitis had significant effects on calving to first AI interval, milk yield, and fat yield, but a non-significant effect on days open, number of inseminations per conception, and milk fat percentage. Mastitic cows had a calving to first AI interval 6.1 days longer and 549.6 kg milk and 20.4 kg fat per 305 days of lactation lower than those with no mastitis. Time of 1st mastitis occurrence did not have any significant effect on reproductive performance. Further, milk and fat yields of cows diseased before peak milk yield were 506 kg and 23.9 kg, respectively, lower than those of cows affected after peak milk yield. Extra attention needs to be paid to mastitis during the early postpartum period.

     

Body condition score at parturition and postpartum supplemental fat effects on cow and calf performance

Three-year-old Angus x Gelbvieh beef cows nutritionally managed to achieve a BCS of 4 +/- 0.07 (479.3 +/- 36.3 kg of BW) or 6 +/- 0.07 (579.6 +/- 53.1 kg of BW) at parturition were used in a 2-yr experiment (n = 36/yr) to determine the effects of prepartum energy balance and postpartum lipid supplementation on cow and calf performance. Beginning 3 d postpartum, cows within each BCS were assigned randomly to be fed hay and a low-fat control supplement or supplements with either high-linoleate cracked safflower seeds or high-oleate cracked safflower seeds until d 60 of lactation. Diets were formulated to be isonitrogenous and isocaloric, and safflower seed supplements were provided to achieve 5% of DMI as fat. Ultrasonic 12th rib fat and LM area were lower (P < 0.001) for cows in BCS 4 compared with BCS 6 cows throughout the study. Cows in BCS 4 at parturition maintained (P = 0.02) condition over the course of the study, whereas cows in BCS 6 lost condition. No differences (P = 0.44 to 0.71) were detected for milk yield, milk energy, milk fat percentage, or milk lactose percentage because of BCS; however, milk protein percentage was less (P = 0.03) for BCS 4 cows. First-service conception rates did not differ (P = 0.22) because of BCS at parturition, but overall pregnancy rate was greater (P = 0.02) in BCS 6 cows. No differences (P = 0.48 to 0.83) were detected in calf birth weight or ADG because of BCS at parturition. Dietary lipid supplementation did not influence (P = 0.23 to 0.96) cow BW change, BCS change, 12th rib fat, LM area, milk yield, milk energy, milk fat percentage, milk lactose percentage, first service conception, overall pregnancy rates, or calf performance. Although cows in BCS of 4 at parturition seemed capable of maintaining BCS during lactation, the overall decrease in pregnancy rate indicates cows should be managed to achieve a BCS >4 before parturition to improve reproductive success.     

The association between first DHI milk-test parameters and subsequent displaced abomasum diagnosis in dairy cows

First Dairy Herd Improvement Corporation (DHI) test milk that was sampled prior to displaced abomasum (DA) diagnosis was used to examine the association between milk yield (kg), fat (%), protein (%), or fat/protein ratio and DA in dairy cows. 27 DA cases were matched to 3 controls per case by herd and calving date. Logistic regression was used to examine the effect of each milk parameter on the odds of DA, adjusting for lactation number and days in milk (DIM) at test. Higher odds of DA diagnosis was found with lower milk yield, higher milk fat percentage, lower milk protein percentage and higher fat/protein ratio. We conclude that milk yield, fat percentage, protein percentage and fat/protein ratio may be used to detect cows at risk for DA. Our findings also indicate that cows diagnosed with DA were energy deficient prior to DA diagnosis.     

奶牛酮病对奶牛生产性能的影响

为了研究奶牛酮病对奶牛生产性能的影响,选取规模奶牛场和散养户共450头奶牛进行跟踪调查,结果表明,规模奶牛场发病率为14.69%,而散养户发病率高达36.92%,其中规模奶牛场的瘫痪型、神经型及消化型酮病分别比散养户低7.16%(P0.05)、6.1%(P0.05)和8.96%(P0.05);秋季发病率比冬季、夏季和春季分别高3.34%(P0.05)、10.89%(P0.05)、13.78%(P0.05);受胎率健康组比酮病组高出50%,差异极显著(P0.01);4胎以上发病率高达47.22%,分别比1胎~4胎高出42.16%(P0.01)、32.13%(P0.01)、29.86%(P0.01)、10.75%(P0.05);泌乳量在31kg以上的奶牛其发病率高达47.76%,分别比泌乳量在21kg~30kg、11kg~20kg、10kg以下的发病率高12.31%(P0.05)、19.86%(P0.01)、25.36%(P0.01),患病前,奶牛的平均日产奶量为17.32kg,而发病后泌乳量降低至7.89kg,差异极显著(P0.01);患病后,其乳成分也发生较大变化,其乳蛋白率、乳脂率、乳糖率及乳干物质分别比患病前降低了1.07%、0.56%、0.73%及3.47%,差异显著(P0.05)。奶牛酮病发病具有一定规律性,可导致奶牛情期延迟、受胎率下降、淘汰率增大、泌乳性能下降及乳质变差。     

Feed intake, lactation performance, blood metabolites and fertility in early lactation dairy cows grazing a timothy pasture

The present study was conducted to investigate feed intake, milk yield, milk composition, blood metabolites and fertility in early lactation dairy cows grazing a timothy pasture. Fourteen multiparous Holstein cows that calved between 20 May and 19 July were used over a 3‐year period. The stocking rate was 3.6–4.3 cow/ha. Concentrates were fed separately at 9.5–11.5 kg/day per cow (dry matter basis) from 1 to 13 weeks postparturition. Herbage intake was estimated using chromium oxide as an indigestible marker. The mean contents of crude protein, total digestible nutrients and neutral detergent fiber of pasture during the 3‐year study period were 22.3%, 71.8% and 51.7%, and those of total diet were 18.9%, 77.3% and 40.3%, respectively. The mean herbage dry matter intake was 13.0 kg/day from 2 to 13 weeks postparturition during the study, total dry matter intake was 23.7 kg/day, the total digestible nutrients sufficiency rate was 105%, milk yield was 39.7 kg/day, and milk fat percentage was 3.30%. The decrease in bodyweight postparturition was slight. Urea nitrogen concentrations in serum were below 18.3 mg/dL. The mean days to first estrus and days open were 36 and 104 days, respectively. These results indicate that energy deficiency, decrease in bodyweight and fertility in early lactation barely occur when high producing dairy cows are fed enough grazing grass and suitable concentrates.