Influence of factors during superovulation on embryo production in Korean Holstein cattle

The aim of this study was to investigate the influence of key parameters (donor parity, milk production, post-parturient day, season and milk recording data) associated with efficiency of embryo recovery (ER) in Holstein cattle. Elite Holstein cows and heifers were selected for ER, while Holstein heifers were used as recipients. The numbers of transferable embryos (TEs) produced were not significantly different when analyzed in terms of donor parity, milk production, postparturient day and season. However, the numbers of TEs were significantly increased when the milk protein (%; P)/fat (%; F) ratio was over 0.95 and/or the milk urea nitrogen (MUN) was between 12 and 18 dl/ml. The results from ET showed no differences in pregnancy rates among Holstein heifers receiving other types, developmental stage codes and quality grades of embryos. The mean interval from ER to artificial insemination was 60.6 days. Moreover, 19 offspring that had milk recording data showed a similar milk yield performance to that of the donor cows. In conclusion, this study showed that in Holstein cows, embryos were recovered and transferred and resulted in production of viable calves. Furthermore, P/F ratio and MUN could be candidate indicators for selection of high-efficiency donor cows.     

复合菌培养物对奶牛产奶性能及体细胞数的影响

试验旨在研究日粮中添加复合菌培养物对奶牛产奶量、乳品质和体细胞数的影响。选择30头荷斯坦奶牛,分为对照组和试验组,对照组饲喂基础日粮,试验组在基础日粮中添加复合菌培养物400 g/(头·d),试验期为37 d。测定指标包括产奶量、乳脂率、乳蛋白率及体细胞数。结果表明,试验组奶牛产奶量比对照组增加6.84%(P>0.05);乳汁体细胞数下降率比对照组提高29.78%(P<0.05);两组奶牛乳脂、乳蛋白之间无明显差异(P>0.05)。本试验结果表明,复合菌培养物在降低体细胞数和改善奶牛产奶性能方面具有良好的效果。     

荷斯坦青年牛初次配种妊娠月龄对头胎和二胎产奶量和繁殖性能的影响

旨在研究母牛初次配种妊娠月龄（age at first pregnancy,AFP）对其泌乳性能和主要繁殖性能的影响。本研究以我国北方地区2个规模化奶牛场13 927头荷斯坦母牛（A牧场8 091头,B牧场5 836头）的生产数据为基础,统计了母牛AFP、头胎和二胎的产奶量、产后首次发情时间、首次配种时间和首次受孕时间,然后将母牛根据AFP的早晚（12~19月龄）分为8组,对各试验组母牛的头胎和二胎产奶量和主要繁殖性能的数据进行比较分析。结果表明：1）2个规模化奶牛场荷斯坦青年牛AFP以13和14月龄为主（总占比70.1%）;2）AFP可显著影响荷斯坦青年牛头胎和二胎的305 d产奶量（P<0.05）,其中AFP为14月龄时A牧场头胎和二胎305 d产奶量均最高,分别为15 102和15 534 kg;3）AFP可显著影响荷斯坦青年牛头胎和二胎产后首次发情时间和受孕时间（P<0.05）,AFP为14月龄时头胎产后首次发情和受孕情况最优;4）对于产后首配时间,除A牧场头胎AFP为16月龄时产后首次配种时间显著高于AFP为17月龄时（P<0.05）外,其余各组间均无显著性差异（P ≥ 0.05）,并且各组间配种时间相差≤ 5 d;5）通过对A牧场在场牛（2 703头）与淘汰牛（660头）的AFP记录数据分析发现,在场牛的AFP为14.52月龄,显著高于淘汰牛的AFP（P<0.05）。因此,在北方地区现有的生产管理水平下,14月龄可能是荷斯坦青年牛最适宜的初次配种妊娠月龄,这对我国规模化奶牛场选择荷斯坦青年牛适宜的初次配种月龄具有一定参考价值。     

Health status and productive performance of somatic cell cloned cattle and their offspring produced in Japan

Since the first somatic cell cloned calves were born in Japan in 1998, more than 500 cloned cattle have been produced by somatic cell nuclear transfer and many studies concerning cloned cattle and their offspring have been conducted in this country. However, most of the results have been published in Japanese; thus, the data produced in this country is not well utilized by researchers throughout the world. This article reviews the 65 reports produced by Japanese researchers (62 written in Japanese and 3 written in English), which employed 171 clones and 32 offspring, and categorizes them according to the following 7 categories: (1) genetic similarities and muzzle prints, (2) hematology and clinical chemistry findings, (3) pathology, (4) growth performance, (5) reproductive performance, (6) meat production performance and (7) milk production performance. No remarkable differences in health status or reproductive performance were found among conventionally bred cattle, somatic cell cloned cattle surviving to adulthood and offspring of somatic cell cloned cattle. Similarities in growth performance and meat quality were observed between nuclear donor cattle and their clones. The growth curves of the offspring resembled those of their full siblings.     

Locomotion Score and Its Impacts on Production Performance and Blood Routine Indexes in Chinese Holstein

To investigate the influencing factors of locomotion score (LS) and its impacts on production performance and blood routine index in Holstein,body condition score (BCS),LS and DHI (dairy herd improvement) of 1 486 lactating cows from two dairy farms,and the blood routine indexes of 101 lactating cows from one farm in Beijing were measured.The fixed model was used to analyze the impacts of herd,parity and lactation stage on LS,and the impacts of LS and BCS on daily milk yield,somatic cell score,milk composition and blood routine indexes in dairy cows.The results showed that both parity and lactation stage had significant impacts on LS.The LS increased with the increase of parit,the LS increased by 0.71 from first lactation to fifth and above lactation.The LS of cow in lactation stage Ⅲ(100-199 d) and Ⅵ (after 350 d) were significantly higher than cow in stage Ⅱ (45-99 d)(P<0.05),and both were higher than 2.The LS had no significant impacts on daily milk yield,milk composition and somatic cell score (P>0.05).However,the milk yield of the cow with LS≥4 was the lowest,and a decrease of 2.29 kg was found compared with the cow with LS=1.Among the various blood routine indexes,LS had significant impacts on red blood cell count,hemoglobin content,mean corpuscular hemoglobin concentration and lymphocyte count (P<0.05),and had no significant impacts on white blood cell count (P>0.05).With the increase of LS,the red blood cell count,hemoglobin content,mean corpuscular hemoglobin concentration and lymphocyte count of cows decreased with different extents.There were some problems on the body immunity and hematopoiesis of cows with poor LS.In dairy farm,regular evaluation of LS could be used to find the management problems of feet and legs,which had a great significance to reduce the loss of production performance and early culling caused by hoof disease.     

中国荷斯坦牛步态评分及其对生产性能和血常规指标的影响

为探究荷斯坦牛步态评分（locomotion score,LS）影响因素及其对生产性能和血常规指标的影响,本研究收集测定了北京地区2个规模化牧场1 486头泌乳牛的体况评分（body condition score,BCS）、LS和DHI（dairy herd improvement）数据,并测定了101头泌乳牛的血常规指标。采用固定模型分析了牧场、胎次和泌乳阶段对LS的影响,以及LS和BCS等因素对日产奶量、体细胞评分、乳成分和血常规指标的影响。结果表明,试验牛的胎次和泌乳阶段均对LS有极显著影响,LS随胎次的升高而增加,从1胎至5胎及以上,LS升高了0.71分;泌乳阶段Ⅲ（100~199 d）、Ⅵ（350 d以后）的LS均显著高于阶段Ⅱ（45~99 d）（P<0.05）,且均高于2分。LS对日产奶量、乳成分和体细胞评分均无显著影响（P>0.05）,但LS≥4分的奶牛日产奶量最低,较LS=1分的奶牛日产奶量降低了2.29 kg。各项血常规指标中,LS对奶牛红细胞数、血红蛋白含量、红细胞平均血红蛋白浓度、淋巴细胞数均有显著影响（P<0.05）,而对白细胞数无显著影响（P>0.05）。随LS升高,奶牛红细胞数、淋巴细胞数、血红蛋白含量和红细胞平均血红蛋白浓度均表现出不同程度的降低。LS较差的奶牛,其机体的免疫力和造血功能会受到不同程度的影响。在规模化牧场中,定期评估牛群的LS能及时发现牛群肢蹄管理的问题,对减少因肢蹄问题引起的生产性能损失和过早淘汰等具有重要意义。     

Development of a Staphylococcus aureus vaccine against mastitis in dairy cows. II. Field trial

A recently described new Staphylococcus aureus vaccine "MASTIVAC I" (Patent no. PTC/IL98/00627) against S. aureus udder infection elicited protection against experimentally induced infection in cows. In the present paper we describe a large-scale vaccination field trial. A total of 452 Israeli Holstein heifers were included in the study over two consecutive years. Approximately half of the heifers (228) were vaccinated while the others (224) served as a control group. Antibody response was detected in all vaccinated animals 4-5 weeks post-primary immunization and it was sustained throughout the experimental period (300-330 days). S. aureus infection could be detected in only 3 out of 228 animals (1.3%) in the vaccinated group and in 6 out of 224 (2.7%) in the control group. These numbers were too low to be statistically evaluated. However, when somatic cell counts (SCC) and milk yields were considered, a significant difference was found between the two groups, namely, the vaccinated cows in first and second lactation had 42 and 54%, respectively, lower SCCs and milk yields 0.5 kg per day higher than the non-vaccinated control cows. These results suggest that the new vaccine elicits a non-specific health improvement of the udder in addition to specific protection against S. aureus.     

Holstein Friesians,Dutch Friesians and Dutch Red and Whites on two complete diets with a different amount of roughage: Performance in first lactation

Groups of 20 Holstein Friesian (HF), 23 Dutch Red and White (DRW) and 20 Dutch Friesian (DF) heifers were fed a complete diet with only roughage (a mixture of grass and corn-silage) or the same mixture of roughage with 50% concentrates on a dry matter basis, from 2 months before the first calving until 10 months after calving.No significant breed-feed composition interactions were found for any of the characteristics.The HF, DRW and DF heifers differed significantly in feed intake and milk production. They consumed 4725, 4432 and 4476 kVEM, respectively, and produced 5331, 4562 and 4660 kg milk, respectively, with 3.96, 4.20 and 4.22% of fat, respectively, and 3.25, 3.49 and 3.40% of protein, respectively.The concentrates and roughage groups differed significantly in feed intake, milk production, average body weight and gain. The respective mean values for the concentrates and the roughage groups were: 5160 and 3928 kVEM, 5534 and 4168 kg milk, 4.00 and 4.26% fat, 3.52 and 3.24% protein, 542 and 506 kg body weight and 97 and 38 kg gain, respectively.HF heifers used 51% of their energy intake for milk production (milk energy), DF heifers 49% and DRW heifers 48%. Both feed composition groups used 49% of their energy intake for milk production, but the roughage group used 8% more of the energy intake for maintenance than the concentrates group, as a result of lower energy intake.     

Post-Death Cloning of Endangered Jeju Black Cattle (Korean Native Cattle): Fertility and Serum Chemistry in a Cloned Bull and Cow and Their Offspring

To preserve Jeju black cattle (JBC; endangered native Korean cattle), a pair of cattle, namely a post-death cloned JBC bull and cow, were produced by somatic cell nuclear transfer (SCNT) in a previous study. In the present study, we examined the in vitro fertilization and reproductive potentials of these post-death cloned animals. Sperm motility, in vitro fertilization and developmental capacity were examined in a post-death cloned bull (Heuk Oll Dolee) and an extinct nuclear donor bull (BK94-13). We assessed reproductive ability in another post-death cloned cow (Heuk Woo Sunee) using cloned sperm for artificial insemination (AI). There were no differences in sperm motility or developmental potential of in vitro fertilized embryos between the post-death cloned bull and its extinct nuclear donor bull; however, the embryo development ratio was slightly higher in the cloned sperm group than in the nuclear donor sperm group. After one attempt at AI, the post-death cloned JBC cow became pregnant, and gestation proceeded normally until day 287. From this post-death cloned sire and dam, a JBC male calf (Heuk Woo Dolee) was delivered naturally (weight, 25 kg). The genetic paternity/maternity of the cloned JBC bull and cow with regard to their offspring was confirmed using International Society for Animal Genetics standard microsatellite markers. Presently, Heuk Woo Dolee is 5 months of age and growing normally. In addition, there were no significant differences in blood chemistry among the post-death cloned JBC bull, the cow, their offspring and cattle bred by AI. This is the first report showing that a pair of cattle, namely, a post-death cloned JBC bull and cow, had normal fertility. Therefore, SCNT can be used effectively to increase the population of endangered JBC.     

Effects of first breeding age on the production and reproduction of Holstein heifers up to the third lactation

The effects of early initiation of first service for dairy heifers on their fertility and productivity up to the third lactation were examined under constant raising and management conditions. Eight Holstein heifers in their early breeding regimens and eight Holstein heifers in their late breeding regimens were initiated to be bred at 12 and 15 months of age, respectively, and were first calved at 21.5 and 25.1 months of age, respectively, with bodyweights of 563 and 638 kg after calving, respectively. Early first breeding resulted in a lower bodyweight and a lower body condition score, but it did not affect the fertility or milk production during the first lactation of heifers as cows. The calving intervals of cows to the second and third calving were similar in early and late bred heifers. Although the early bred heifers had a significantly lower fat‐corrected milk yield at the second lactation than that of the late bred heifers, early breeding did not impair the productivity indicated by the mean milk yield per day from birth to the end of the third lactation with a shorter production period.     

Effect of rumen protected methionine supplementation on early lactational responses of dairy cows fed a grass silage and cereals diet.

To investigate the milk production limiting potential of a diet based on grass silage (40%), hay (15%), dried sugar beet pulp (13%) and grain compound mixture (32%), 28 multiparous cows in early lactation were randomly assigned to two treatment groups: a control group and a group receiving supplementary rumen protected methionine (RPMet) treatment (12 g intestinally available methionine/cow/day, given 1-120 days postpartum; Smartamine; RPAN's technology). The diet was formulated to meet the requirements for protein and net energy. RPMet supplementation had no significant effect on DMI (kg/cow/day), milk dry mass, milk lactose and milk urea contents. Responses for mean daily milk yield, mean milk fat and milk protein yields were significantly higher (P < 0.05) in cows supplied with RPMet than in controls. Mean daily milk yield, milk protein and milk fat yields increased by 2.4 kg, 108 g and 124 g, respectively. The mean daily milk protein and casein contents were increased by 1.8 g and 0.9 g and milk fat content by 1.2 g in 1 kg of milk, respectively. The results suggest that in cows fed grass silage and a grain compound mixture milk production is limited by methionine insufficiency, but milk production performance can be increased significantly by the addition of RPMet to the diet.     

MET基因多态性与中国荷斯坦牛繁殖和泌乳性状的关联分析

为筛选与中国荷斯坦牛繁殖和泌乳性状相关的遗传标记，本研究从分子水平探究了MET基因单核苷酸多态（single nucleotide polymorphisms，SNPs）与繁殖和泌乳性状的相关性。通过混池测序法在70头无血缘关系的健康中国荷斯坦公牛中扫描目标基因的SNPs，采用竞争性等位基因特异性PCR （kompetitive allele-specific PCR，KASP）对其后代1 160头中国荷斯坦泌乳牛进行部分SNP的基因分型，基于连锁不平衡分析获得双倍型信息，并采用线性模型对SNP及其双倍型与5个繁殖和6个泌乳性状的估计育种值（estimated breeding values，EBV）进行关联分析。随后，针对位于功能区域的SNPs进行生物信息学分析和基因表达量相关性分析，初步探究其潜在的调控机制。本研究在MET基因中共检测到19个SNPs，说明该基因存在丰富的遗传变异；就其中7个SNPs进行了基因分型，分型结果与目标性状的关联分析结果显示，7个SNPs与多个性状存在显著（P<0.05）或极显著（P<0.01）的关联；位于上游调控区的g.51737889T>C位点GG基因型个体的初产日龄、青年牛首末配种间隔、经产牛首末配种间隔、体细胞评分的EBV最低，说明该基因型个体同时具有较好的繁殖性能和泌乳性能；另一个位于上游调控区的g.51736640A>C位点GG基因型个体的初产日龄、青年牛首末配种间隔、经产牛首末配种间隔、体细胞评分的EBV最低，但乳蛋白率、乳脂率的EBV最低，说明该基因型个体繁殖性能较好，但泌乳性能相对较差；此外，位于第6外显子的g.51660569G>A位点TC基因型个体初产日龄的EBV较低，青年牛首末配种间隔、经产牛首末配种间隔、体细胞评分的EBV最低，说明该基因型个体具有较好的繁殖性能。连锁不平衡分析发现，该基因的7个SNPs形成2个单倍型块，其双倍型与目标性状的关联分析进一步表明，单倍型块1中H1H3个体的繁殖性能较好且泌乳性能中等，单倍型块2中H4H4个体的繁殖性能和泌乳性能均较优秀，为两个优势双倍型；此外，H1H3包含g.51660569G>A位点的TC基因型，H4H4为g.51737889T>C、g.51736640A>C两位点GG基因型的组合，其关联分析结果与单个位点的结果一致。基序分析结果表明，g.51737889T>C与g.51736640A>C位点的优势等位基因G可富集到与基因激活、细胞增殖、分化相关的转录因子，且两位点GG基因型的MET基因表达量均最高，其双倍型H4H4表达量也较高，进一步验证了关联分析结果。综上，本研究获得了中国荷斯坦牛MET基因的多态性图谱，并通过关联分析、生物信息学预测及基因表达量分析发现并验证了MET基因与繁殖、泌乳性状的遗传关联，为中国荷斯坦牛高产高效选育提供了可用的遗传标记。     

克隆荷斯坦牛的生长、繁育和生产性能

本文报道了12头加系荷斯坦克隆母牛的生长发育、配种繁殖和生产性能状况．比较了克隆牛和非克隆牛的部分生产指标。结果表明,在良好的饲养管理条件下,克隆牛的平均初生重、6月龄、18月龄和1产后体重分别达41．6、191．8、520．8和651．1kg;第1次配种月龄为16．7个月。受孕月龄为19．2个月,产犊月龄为28．6个月;第1泌乳期305d产奶量为7029．7kg,乳脂率3．73％,乳蛋白率3．27％．符合加系荷斯坦牛的生产性能指标。克隆牛生长发育和产奶量指标均略高于非克隆牛,但产间距比非克隆牛长。克隆牛疾病发生情况、类别、治疗效果和非克隆牛相似：有2头克隆牛死于心脏病．其原因有待作深入研究。     

荷斯坦牛冻精改良西藏黄牛的泌乳性能分析

[目的]西藏拉萨市引进荷斯坦牛冻精与本地黄牛级进杂交已40余年,对荷斯坦牛改良西藏黄牛（荷×藏）级进杂交后代泌乳性能进行测定,为后期横交固定育种工作提供基础数据和科学依据。[方法]统计并比较2017—2021年荷×藏高代次不同胎次之间的总泌乳量、高峰产奶量、高峰日、产奶天数和日泌乳量;2021年7月进行奶牛生产性能测定（DHI）。[结果]荷×藏高代次随着胎次增加总泌乳量、高峰产奶量、泌乳天数和日泌乳量随之降低,高峰泌乳日在正常范围内;3个胎次之间,总泌乳量主要集中在2000 ~ 4000 kg,高峰产奶量主要集中在15 kg ~ 25 kg,高峰日、产奶天数和日泌乳量的范围分别是49.58 d ~ 66.30 d、212.06 d ~ 217.36 d和14.96 kg ~ 17.99 kg。DHI测定数据显示荷×藏高代次群体乳脂率、乳蛋白率和尿素氮分别是3.86 %、3.34 %和12.47 mg/dL。[结论]高原低氧环境限制限制了荷×藏高代次牛的泌乳性能,但相比西藏黄牛有较大提高,结果可作为提高改良牛生产性能、产奶量、奶品质及遗传特性提供基础数据。     

Evaluation of the impact of parasite control with the IVOMEC SR Bolus given at breeding age on first lactation yield in Holstein heifers.

This field trial was conducted to test the effect of treatment with a sustained-release ivermectin bolus on first lactation milk production (projected to 305 days) and milk composition (percent fat and protein) in breeding-aged Holstein heifers. From 12 herds, 96 heifers were randomly allocated at turnout to treatment with a commercially available ivermectin bolus (n=49) or untreated control (n=47) groups. Animals were weighed at turnout, mid-season, and at the end of the grazing season. Fecal samples were taken and nematode eggs counted. Projected 305 days milk production, fat and protein content were retrieved from PATLQ reports (Quebec DHI records) for heifers that calved during the subsequent 10 months. The heifers had a mean weight of 409 and 404 kg at turnout, respectively, for control and treated groups. Nematode egg excretion was relatively low (mean of 10 egg/g (EPG) for controls at housing) throughout the pasture season. The average daily gain (ADG) and total weight gain (TWG) over the entire pasture season was found to be higher in treated heifers compared to controls (ADG: difference=0.08 kg per day, P=0.010; TWG: difference=12.82 kg, P=0.013). Taking into account a possible farm effect, the 305 days milk production for IVOMEC SR bolus-treated heifers was significantly higher than for untreated animals (mean+/-S.D.; 348+/-476 kg; t-test=2.31, P<0.05). Overall, 8 of the 10 remaining farms in the study demonstrated a positive milk production difference in treated (n=34) versus control heifers (n=33). The results of this study suggest that preventive treatment of breeding-aged, grazing dairy heifers with a sustained-release ivermectin bolus provides a significant weight-gain which may translate to a significant milk production advantage, even in situations with commercial utilization of moderately contaminated pastures.     

Control of heifer mastitis: antimicrobial treatment-an overview

Initial studies in Louisiana, USA to determine the prevalence of mastitis in breeding age dairy heifers demonstrated that intramammary infections (IMIs) were present in 97% of heifers and 75% of quarters. Most common isolates were Staphylococcus aureus, Staphylococcus hyicus, and Staphylococcus chromogenes; somatic cell counts (SCCs) ranged from 12.4 to 17.3 x 10(6)ml(-1). Histologic examination of Staph. aureus-infected quarters demonstrated significant reductions in alveolar epithelial and luminal areas, and increases in connective tissue and leukocytosis, illustrating limited secretory development and marked inflammation. A one-time infusion of various nonlactating cow antibiotic preparations into infected quarters during different stages of gestation but >45 days prepartum resulted in cure rates for Staph. aureus IMI of 67-100%. Mean SCC was 50% lower at calving for treated heifers, and milk yield over the first 2 months of lactation was 10% greater than that of untreated controls. Subsequent multiple herd studies, however, revealed that use of nonlactating cow therapy was beneficial only in herds exhibiting a high prevalence of heifer mastitis and not in low prevalence herds. Results of lactating cow antibiotic therapy infused 1-2 weeks prepartum demonstrated cure rates of 59-76% vs. 26-31.7% in untreated controls. In some studies, milk production during the first lactation in treated heifers was approximately 10% higher than untreated controls, and SCC were significantly lower; however, in other studies, prepartum treatment was successful in reducing prevalence of infection but had no effect on SCC or milk yield during the subsequent lactation. Thus, treatment of heifers is advantageous because the cure rate is much higher than during lactation, there is no milk loss, and risk of antibiotic residues minimal; however, successful therapy may not necessarily result in lowered SCC and increased milk production in all herds.     

Converting to organic dairy farming: Consequences for production, somatic cell scores and calving interval of first parity Holstein cows

This paper aims to describe the changes prompted by conversion to organic farming for milk production and fertility of first parity Holstein cows.

Data was collected for Dutch organic farms, with a distinction made between long-standing-organic farms, converted organic farms and a reference group of conventional farms. The percentage Holstein blood in the herds, milk production (kg milk, % milk fat, % milk protein), somatic cell scores (SCS), calving interval (CI) and age at first calving (AFC) were described over time. An animal model was used to estimate the effects of conversion on different traits based on data from converted organic farms.

Milk production was lower and somatic cell counts were higher on long-standing-organic farms than on conventional and converted organic farms. Interestingly, at pre-organic farms, i.e. before their conversion, the milk production level was already lower than at conventional farms.

The estimates from our statistical analysis showed a highly significant decrease in milk yield and protein percentage due to conversion. Also fat content decreased, SCS increased and AFC increased significantly.

It can be concluded that the conversion to organic farming is a gradual process over years. Dutch farmers who decided during the late 1990s to convert to organic farming, represented a specific group of farmers distinct from conventional farmers, which was reflected by lower milk yields, milk fat percentage and protein percentage before conversion as compared to conventional farms. During conversion, significant changes in milk production, protein and fat contents and somatic cell scores took place. Age of first calving is an important difference between organic and conventional farming.     

Management, feeding, production, reproduction and udder health on organic and conventional Swiss dairy farms

Organic dairy farms (OP; n=60) and conventional dairy farms (integrated production, IP; n=60), matched in size, location, and agricultural zone (altitude), were studied for possible differences in management, feeding, production, reproduction and udder health. OP and IP farms were similar in size (17.7 and 16.9 ha), milk quota (65900 and 70,000 kg/year), cow number (14 and 15), cow age (5.3 and 5.2 years), housing of cows of the Simmental x Red Holstein or Holstein breeds (87 and 75%; 45 and 60%), but differed significantly with respect to loose housing systems (18 and 7%), outside paddocks (98 and 75%), energy-corrected 305-d milk yield (5,695 and 6,059 kg), milk protein content (31.8 and 32.7 g/kg), use of bucket milking systems (73 and 33%), observance of regular (12-h) milking intervals (47 and 68%), routine application of the California-Mastitis-Test (10 and 28%), teat dipping after milking (25 and 43%) and blanket dry cow treatments (0 and 45%). Milk somatic cell counts on OP and IP farms (119 000 and 117,000/mL) and reproduction data were similar and there were no significant differences between OP and IP farms as concerns available feeds, planning and management of feeding. Alternative veterinary treatments were used more often on OP than IP farms (55 and 17%). Main causes for cow replacements on OP and IP farms were fertility disorders (both 45%), age (40 and 42%), sale (30 and 37%) and udder health (35 and 13%).Between OP and IP Swiss dairy farms thus relatively few larger differences were found.     

Production characters of primiparous females of a five-breed diallel

Data included pubertal, reproductive and lactation records of primiparous females produced in a diallel of Angus, Brahman, Hereford, Holstein and Jersey. Brahman heifers were oldest, tallest and heaviest at puberty, while Jersey heifers were youngest, shortest and lightest. Crossbred heifers were 22 d younger (P less than .01) at puberty than straightbred heifers; no significant differences were detected between the two groups for weight or height at puberty. Dairy heifers (Holstein and Jersey) required fewer services (P less than .05) to conception than beef heifers. The difference between straightbred and crossbred heifers for number of services to conception was small and nonsignificant. Rank of straightbreds for age at conception was similar to their rank for age at puberty except that Holstein required 1.2 fewer services and were younger at conception than Jersey. Crossbreds were 41 d younger (P less than .05) at conception than straightbreds. Brahman had the longest gestation length and were oldest at first calving; Jersey had the shortest gestation length and Holstein were youngest at first calving. Straightbred heifers gestated 1.3 d longer and were 45 d older (P less than .05) at first calving than crossbred heifers. Dairy females had greater peak and total milk yield than beef females (P less than .01). Overall straightbred and crossbred means for peak milk yield and total milk yield did not differ significantly.     

复合酶对奶牛产奶量和乳成分的影响

本试验旨在研究复合酶对奶牛产奶量和乳成分的影响。选择胎次、泌乳天数、产奶量相近的健康荷斯坦泌乳牛30头,随机分为2组,即试验组和对照组,试验组每日在TMR中添加复合酶制剂50g。结果显示,试验组奶牛日均产奶量对比照组提高了6．6％,差异显著（P〈0．05）;试验组乳蛋白率比对照组提高0．19％,差异显著（P〈0．05）,乳脂率比对照组提高0．3％,差异显著（P〈0．05）,乳糖含量比对照组提高0．2％;经济效益每天每头奶牛比对照组多盈利3．88K。说明每日在奶牛TMR中添加50g复合酶,可提高奶牛产奶量,改善牛奶品质,增加经济效益。