An economic analysis of hyperketonemia testing and propylene glycol treatment strategies in early lactation dairy cattle

The purpose was to develop stochastic economic models which address variation in disease risks and costs in order to evaluate different simulated on-farm testing and propylene glycol (PG) treatment strategies based on herd hyperketonemia (HYK) incidence during the first 30 DIM. Data used in model development concerning the difference in health and production consequences between HYK and non-ketotic cows were based on results from 10 studies representing over 13,000 cows from 833 dairy farms in North America, Canada, and Europe. Inputs for PG associated variables were based on a large field trial using cows from 4 free-stall dairy herds (2 in New York and 2 in Wisconsin). Four simulated on-farm testing and treatment strategies were analyzed at herd HYK incidences ranging from 5% to 80% and included: 1) treating all cows with 5 d of PG starting at 5 DIM, 2) testing all cows for HYK 1 day per week (e.g. Mondays) from 3 to 16 DIM and treating all positive cows with 5 d of oral PG, 3) testing all cows for HYK 2 days per week (e.g. Mondays and Thursdays) from 3 to 9 DIM and treating all positive cows with 5 d of oral PG, and 4) testing all cows for HYK 3 days per week (e.g. Mondays, Wednesdays, and Fridays) from 3 to 16 DIM and treating all positive cows with 5 d of oral PG. Cost-benefit analysis included the costs associated with labor to test cows, β-hydroxybutyrate test strips, labor to treat cows, PG, and the associated gain in milk production, decrease in DA and early removal risks of PG treated HYK positive cows compared to non-treated HYK positive cows. Stochastic models were developed to account for variability in the distribution of input variables. Per 100 fresh cows in a herd with an HYK incidence of 40%, the mean economic benefits of the 4 different strategies were $1088, $744, $1166, and $760, respectively. Testing cows 2 days per week from 3 to 9 DIM was the most cost-effective strategy for herds with HYK incidences between 15% and 50%; above 50%, treating all fresh cows with 5 d of PG was the most cost-effective strategy. These results show that for herds similar to those used in model, when herd HYK incidences rise above 25%, almost any HYK testing and treatment protocol will be economically beneficial for the farm.     

Colostrogenesis during an induced lactation in dairy cattle

Colostrum immunoglobulin G (IgG) is of major importance for the newborn calf because epitheliochorial placentae do not provide transport in utero. The formation of colostrum occurs in the later stages of pregnancy. Our objectives were to induce lactation in non‐pregnant dairy cows and (i) to determine the changes of IgG in serum and mammary secretions during the induction process and (ii) to establish α‐lactalbumin (αLA) and prolactin (Prl) alterations to monitor the changing mammary epithelial tight junction status and development pattern. Estradiol‐17β (E2) and progesterone (P4) injections in a 1–7 days series were combined with a 3‐day injection series (day 21–23) of dexamethasone (DEX). Blood and both front quarter secretion samples were collected daily. Milking started 24 days after the start of the experiment. Results show that the mammary secretory IgG1 was increased at >7 days after the start of steroid injections and depicted a bimodal pattern reaching a high of 16 mg/ml at 21 day compared with 3.2 mg/ml in the serum. There was a small increase in secretory IgG2 that did not correlate with tight junction status, but never reached the serum concentration. The injections of DEX resulted in constriction of tight junctions. Secretory αLA was immediately increased with steroid injections, dropped precipitously after 7 days and then began a steady increase until the start of milking. Changes in serum αLA are related to mammary tight junctions while serum Prl gradually increased from 30 to >60 ng/ml after the steroid injections stopped. These results provide insights into the mechanisms and timing of colostrogenesis during an induced lactation protocol.     

Oxidative status during late pregnancy and early lactation in dairy cows

In the last few years, the detection of free radical damage and the body's defences against it have become increasingly important in clinical medicine as a complementary tool in the evaluation of metabolic status. The aim of this study was to evaluate, under field conditions, the anti-oxidant status of healthy cows during late pregnancy and lactation onset using two parameters: (1) plasma levels of malondialdehyde (MDA), a degradation product of lipid peroxidation, and (2) total antioxidant status (TAS). Results were compared with those obtained in another group of cows with lesser metabolic demands. We also investigated possible relationships between antioxidant status markers and other relevant blood parameters. Our results confirmed the characteristic metabolic changes associated with late pregnancy and early lactation. MDA and TAS provided an accurate reflection of the internal physiological status of the animal. The data indicated increased lipid peroxidation around parturition, but with wide individual variations that may be attributable not only to the physiological stage but also to unknown factors that will have to be further considered in future studies.     

Associations between the time of conception and the shape of the lactation curve in early lactation in Norwegian dairy cattle

Background

This study was carried out to determine if an association exists between the shape of the lactation curve before it is influenced by the event of conception and the time from calving to conception in Norwegian dairy cattle. Lactation curves of Norwegian Red cows during 5 to 42 days in milk (DIM) were compared between cows conceiving between 43 and 93 DIM and cows conceiving after 93 DIM.

Methods

Data from 23,049 cows, represented by one lactation each, with 219,538 monthly test days were extracted from the Norwegian Dairy Herd Recording System, which represents 97% of all Norwegian dairy cows. Besides veterinary treatments, these records also included information on daily milk yield at monthly test days. The data were stratified by parity groups (1, 2, and 3 and higher) and time to conception periods (43-93 DIM and >93 DIM). The sample was selected using the following selection criteria: conception later than 42 DIM, calving season July to September, no records of veterinary treatment and the level of energy fed as concentrates between 8.69 and 12.83 MJ. The shape of the lactation curves were parameterized using a modified Wilmink-model in a mixed model analysis. Differences in the parameters of the lactation curves with different conception times were evaluated using confidence intervals.

Results

Lactation curves characterized by a low intercept and a steep ascending slope and a steep descending slope were associated with early conception across all parities. The peak milk yield was not associated with time of conception.

Conclusions

A practical application of the study results is the use of the shape of the lactation curve in future herd management. Groups of cows with impaired reproductive performance may be identified due to an unfavorable shape of the lactation curve. Monitoring lactation curves and adjusting the feeding strategy to adjust yield therefore may be useful for the improvement of reproductive performance at herd level.     

规模化奶牛饲养中的饲料及加工设备

（接９期）四、TMR日粮及其加工设备任何饲养体系或方法的目标就是为奶牛提供能够采食到足够数量的营养日粮。实践表明TMR日粮是比较先进的饲喂方式，在发达国家得到普遍运用。２０００年以前，我国只有少数先进的奶牛场采用TMR机械化饲喂，绝大部分奶牛场采用的是传统的落后的饲喂方式。２００２年３月国家科技部《关于“奶业重大关键技术研究与产业化技术集成示范”重大专项实施的工作方案》中明确指出：“推广应用现代全混合日粮饲喂技术和配套饲养工艺”，这将有力地推动这一技术的广泛应用。１．传统饲喂方式的缺点牛饲料不同于鸡…     

Systemic granulomatous disease in dairy cattle during a dicyandiamide feeding trial

CASE HISTORY: Mature, in-calf, non-lactating, Friesian or Friesian-cross cows were fed dicyandiamide (DCD) at daily doses of 0.15 g/kg (Group 1; n=31), 0.45 g/kg (Group 2; n=21) and 0.75 g/kg (Group 3; n=12), as part of a safety trial, which also included a control group (n=15). Daily health observations were carried out on each cow until Day 86 of the study. On Day 28 one cow from Group 3 was observed with signs of disease, and subsequently disease was noted in other cows.

CLINICAL FINDINGS: Clinical signs in the first case included depression, pyrexia (40.9°C), salivation and dehydration, in addition to progressive weight loss, followed by death on Day 32. Other cows from all treatment groups developed clinical signs of disease resulting in euthanasia of seven animals. Disease occurred in 10/12 (83%) cows in Group 3, 11/21 (52%) cows in Group 2, and 7/31 (23%) cows in Group 1. Clinical signs were variable and included dermatitis and pruritus of the head and neck, petechial haemorrhages, pyrexia, weight loss, thrombocytopenia, neutropenia, and regenerative anaemia.

PATHOLOGICAL FINDINGS: Gross findings included generalised lymphadenopathy, subcutaneous oedema, petechiation of mucosal and serosal surfaces, and gastrointestinal haemorrhage. Histologically, multiple organs and tissues contained inflammatory foci characterised by infiltrates of lymphocytes, plasma cells, macrophages and occasionally prominent multinucleated giant cells and eosinophils.

DIAGNOSIS: Multisystemic granulomatous and haemorrhagic syndrome resembling cell-mediated hypersensitivity, associated with DCD ingestion.

CLINICAL RELEVANCE:: This is the first report of toxicity in cattle associated with ingestion of DCD. The proportion of affected cows increased with increasing dose of DCD, but not all cattle in the high dose group developed disease, therefore additional factors may determine whether or not an individual cow will develop DCD-associated disease.     

紫花苜蓿饲喂奶牛试验

通过紫花苜蓿Medicago sativa饲喂奶牛对比试验,结果发现:紫花苜蓿营养丰富,是饲喂奶牛的最佳粗饲料,不论青饲还是调制成干草,适口性都很好,可显著提高奶牛产奶量,增加奶农户经济收入.充分利用兰州市紫花苜蓿的资源优势, 增加奶牛日粮中紫花苜蓿的比例,提高奶牛单产水平,降低生产成本,提高经济效益,通过示范户的带动,大力推广种植紫花苜蓿,改变奶农户以精料为主的传统饲养方式.     

多年生紫花苜蓿饲喂奶牛试验研究

紫花苜蓿营养丰富,是奶牛饲草的最佳粗饲料,不论青饲还是调制成干草,适口性都很好,用于饲喂奶牛可显著提高奶牛产奶量,增加奶农户经济收入。     

The effect of intra-ruminal selenium pellets on growth rate, lactation and reproductive efficiency in dairy cattle

In each of two dairy herds (A and B), rising yearling heifers (Trial 1) and adult cows (Trial 2) were assigned to three treatment groups. Untreated animals were compared to animals treated with either two or four intra-ruminal pellets containing 3 g of elemental selenium. The administration of pellets at the recommended dose (two pellets per animal) was effective in elevating whole blood glutathione peroxidase activity and selenium concentration to over 10 times those of control animals. In Trial 1, a 15% response in liveweight gain (p<0.001) occurred in yearling heifers in the herd with the lowest pre-treatment selenium status. In Trial 2, cows receiving two pellets produced a greater milk volume (p=0.06) and more milk solids (p=0.02) than untreated controls; an increase in volume of 5.4% and 8%, and in milk solids of 6.5% and 6.4%, were noted in herds A and B respectively. There was a trend towards decreasing somatic cell counts in milk from the treated cows when compared to controls, the four-pellet group in Herd A and the two-pellet group in Herd B being significantly different from their respective control group. No between-group differences were noted in calving-first service or calving-conception intervals, nor in the proportion of animals pregnant to first or all services. The administration of selenium at twice the recommended dose rate yielded no additional response above that noted after the administration of the recommended dose. The results of this study support the use of currently recommended Ministry of Agriculture and Fisheries selenium reference ranges in cattle for the prediction of a response to supplementation.     

The effect of intra-ruminal selenium pellets on growth rate,lactation and reproductive efficiency in dairy cattle

In each of two dairy herds (A and B), rising yearling heifers (Trial 1) and adult cows (Trial 2) were assigned to three treatment groups. Untreated animals were compared to animals treated with either two or four intra-ruminal pellets containing 3 g of elemental selenium. The administration of pellets at the recommended dose (two pellets per animal) was effective in elevating whole blood glutathione peroxidase activity and selenium concentration to over 10 times those of control animals.

In Trial 1, a 15% response in liveweight gain (p<0.001) occurred in yearling heifers in the herd with the lowest pre-treatment selenium status. In Trial 2, cows receiving two pellets produced a greater milk volume (p=0.06) and more milk solids (p=0.02) than untreated controls; an increase in volume of 5.4% and 8%, and in milk solids of 6.5% and 6.4%) were noted in herds A and B respectively. There was a trend toyards decreasing somatic cell counts in milk from the treated cows when compared to controls, the four-pellet group in Herd A and the two-pellet group in Herd B being significantly different from their respective control group. No between-group differences were noted in calving-first service or calving-conception intervals, nor in the proportion of animals pregnant to first or all services. The administration of selenium at twice the recommended dose rate yielded no additional response above that noted after the administration of the recommended dose. The results of this study support the use of currently recommended Ministry of Agriculture and Fisheries selenium reference ranges in cattle for the prediction of a response to supplementation.     

Feeding strategies for managing heat load in feedlot cattle

Eighty-four Bos taurus crossbred steers were used to investigate effects of level and duration of limit-feeding feedlot cattle in a hot environment. Pens (four/treatment) of steers (seven/pen) were fed feedlot finishing diets and randomly assigned to the following treatments: 1) restricted to approximately 75% of feed consumed when offered ad libitum for 21-d duration (RES21); 2) restricted to approximately 75% of ad libitum for 42-d duration (RES42); and 3) feed offered ad libitum (ADLIB). Tympanic temperatures (TT) were measured via thermistors placed in the ear canal and attached to data loggers. Restricting feed intake for both 21- and 42-d reduced tympanic temperature when compared with ADLIB treatment groups under hot environmental conditions. Temperature reductions exceeded 0.5 degrees C (P < 0.05) depending on time of day. The reduced tympanic temperature is likely due to a reduction in metabolic heat load and/or a concurrent reduction in metabolic rate. Within respective periods, no differences (P > 0.05) were found among treatments for panting or bunching score. However, different proportions of cattle were found to be bunching and panting with ADLIB cattle displaying a greater number of bunched steers that were panting when compared with the other groups. When averaged across diet treatments, dark-colored cattle had the greatest percentage of cattle showing moderate to excessive panting, while light-colored cattle displayed the least panting under thermoneutral climatic conditions. Under hot (mean daily temperature-humidity index >74) conditions, dark-colored cattle tended to bunch more (P = 0.073) and pant more (P < 0.01) than light-colored cattle. Mean TT were 0.2 to 0.6 degrees C (P < 0.05) greater for dark- vs light-colored cattle under hot conditions. Limit-feeding feedlot cattle during early summer is a successful tool for enhancing animal comfort by alleviating the combined effects of high climatic and metabolic heat load.     

Half-life,clearance and production rate for oxytocin in cattle during lactation and mammary involution I

Basal concentration, production rate, metabolic clearance rate and $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ for oxytocin were measured in Holstein cows at three lactational stages and during mammary involution. At each lactational stage, oxytocin was given intravenously at .5 IU/min or 1.0 IU/min for 60 min. Infusions were preceded by priming. During involution, the high dose was used. Mean basal concentrations of oxytocin ranged from 8.7 to 21.4 uU/ml. Mean basal values at early, middle, late lactation and involution were 17.57, 12.33, 15.15, 21.13 uU/ml, respectively and differed significantly. The mean “rapid” $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ was 3.87 ± .1 min. Early, middle, late lactation and involution $\text{T}\text{1}\text{2}\text{s}$ were 4.2, 3.7, 4.0 and 3.5 min, respectively. The rapid $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ was not affected by lactational stage. The mean “slow” $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ was 25.53 ± 1 min. Early lactation and dry period means differed significantly. The overall mean oxytocin clearance rate was 8.41 ± .1 ml/kg^·min. Clearance rate declined through lactation and into the dry period. Mean values of 9.3, 8.8, 7.8 and 7.1 ml/kg^·min were obtained at early, middle, late lactation and involution, respectively. Clearance rates at late lactation and involution differed significantly from one another and from the early and middle stages. Mean entry rates for oxytocin at early, middle, late lactation and involution were 168.79, 106.03, 111.1 and 146.8 uU/kg^·min, respectively. Measurements at early lactation and involution were greater than values for middle and late lactation. To summarize, basal oxytocin concentrations can be measured in cows that are lactating or undergoing mammary involution and changes in concentrations during lactation are related to hormone production (entry rate) and metabolic clearance rates.     

泌乳早期发情和乏情奶牛机体代谢和生殖机能的变化

在某一集约化牛场,随机选取奶牛30头,在奶牛产后发情期(50～90 d)内根据奶牛是否发情将奶牛分为发情组和乏情组。通过对试验奶牛血液生化指标(Glu、BHBA、NEFA)、内分泌指标(FSH、LH、LP、E2、P4)等进行调查和检测。结果显示:当奶牛发情时,机体血浆Glu、FSH、LH、E2和LP浓度高,血浆NEFA、P4浓度低,但乏情时正好相反。当奶牛发情时,血浆leptin与LH、E2呈显著正相关,与P4呈显著负相关,但乏情奶牛未呈现相关性。这些结果提示奶牛乏情与机体能量代谢状况和Ins、Gn、E2、P4、Lp分泌少有关。能量平衡能促进奶牛产后发情,与机体高水平血糖、Lp、FSH、LH、E2和低水平P4、NEFA有关。LP是奶牛泌乳早期发情的一个重要调控因子,在奶牛产后能量平衡、生产性能和繁殖性能之间起到一个平衡纽带的作用。     

Levels of milk urea, plasma constituents and rumen liquid ammonia in relation to the feeding of dairy cows during early lactation

The study was undertaken to establish the relationships between milk and plasma urea levels and protein supply, using traditional and new measures of feed protein value. Samples of milk and plasma were taken before morning feeding twice weekly for the first 3 months post partum from 21 multiparous cows and 7 heifers. Samples of rumen fluid were collected every second week. The cows were distributed into 4 different feeding groups. Feeding regimens were factorial with respect to protein content of the concentrates (i.e. Low protein (Lp): 12.5% digestible crude protein (DCP) vs. High protein (Hp): 17.5% DCP) and concentrate allowances (i.e. Low energy (Le): substandard vs. High energy (He): standard). Silage was offered ad libitum. The within-animal coefficients of correlation between milk and plasma urea levels, and between milk urea levels and the levels of ammonia in the rumen fluid wer r = 0.88 (p less than 0.001) and r = 0.75 (p less than 0.001), respectively. Analysis of variance showed the following sources of urea variation to be significant: Protein balance in the rumen (PBV), intake of DCP, intake of amino acids absorbed in the intestine (AAT), intake of fattening feed units, and the individual animal factor. A similar tendency was found for the variation of ammonia in rumen fluid. The coefficients of determination (R2 model) were not increased by introducing protein balance (BADCP), the amount of PBV and AAT in the dry matter ingested, or the protein/energy ratio as alternative parameters of protein intake in the models. The levels of protein or energy intake did not significantly influence the levels of plasma albumin. The correlations between urea levels and other plasma indicators of metabolic status and liver function were generally low.     

亚临床酮病对泌乳早期奶牛繁殖性能的影响

为探究围产期亚临床酮病与泌乳奶牛繁殖性能及卵泡发育之间的关系,本试验选择了黑龙江省某大型集约化牛场开展试验,根据产后血酮水平确定亚临床酮病组和健康组奶牛共80头,该牛场亚临床酮病发生率为71%;两组奶牛跟踪到产后50 d进行直肠检查和B超检查了解卵泡发育状况,并记录繁殖性能数据。结果显示:与健康组奶牛相比,亚临床酮病组奶牛产后首次发情天数延长10 d,产后60 d内发情次数少0.58次;产后50 d子宫复旧不全高15%,与亚临床酮病呈显著正相关(R^2=8.74);产后60 d卵泡直径小3 mm(P<0.05)。结论:该牛场奶牛亚临床酮病发病率较高,是引起奶牛产后繁殖障碍的风险因素,也是造成卵泡发育受阻的不良因素,会导致奶牛繁殖力下降。     

Computer-controlled milk replacer feeding strategies for group-reared dairy calves

The objective of this study was to compare the effects of ad libitum and restricted computer-controlled milk replacer (MR) feeding strategies on performance of group-reared dairy calves during preweaning (from 0.5 to 2.0 months of age), weaning (2.0 to 2.5) and postweaning (2.5 to 6.0) periods. Two feeding trials comprised a total of 34 Finnish Ayrshire and 6 Holstein–Friesian bull calves. The calves were randomly (balanced for breed) allotted to pens (5 calves/pen) which were thereafter randomly allotted to two experimental treatments: 1) ad libitum MR feeding (F) with ad libitum access to MR and 2) restricted MR feeding (R) where the calves were given 6.0 L of MR daily. All the calves had free access to water, commercial starter and grass silage before weaning. The weaned calves had free access to water and silage and were given 3 kg/day (air-dry basis) of a concentrate mixture. Due to increased metabolizable energy intake (16.4 vs. 12.7 MJ/day; P < 0.05), the daily gain of the F calves was higher (690 vs. 543 g/day; P < 0.05) than that of the R calves during the preweaning period. Due to the more rapid increase in concentrate intake of the R calves during the weaning period the R calves grew better than the F calves (482 vs. 1038 g/day; P < 0.01) and the differences in live weight evened out during the weaning period. During the postweaning period there were no treatment differences in feed intake or gain. The average gain during the whole study was not affected by either of the treatments. Ad libitum feeding increased the variation in the MR intake and gain compared to restricted feeding.     

保护性脂肪在奶牛饲养中的应用

保护性脂肪属于过瘤胃脂肪，在奶牛日粮中添加保护性脂肪可以提高奶牛的产奶量、乳脂率和繁殖性能。保护性脂肪适用于高、中产奶牛，在日粮中的添加量一般为3％－5％。     

微生物添加剂饲喂奶牛效果观察

用多种芽孢杆菌、乳酸杆菌、酵母菌等按不同比例混合制成6种微生态制剂,分别添加于奶牛饲粮中以观察其对奶牛的生产性能--泌乳数量及其质量的影响来筛选奶牛用的最佳微生物添加剂组合,再用最佳组合的不同剂量饲喂奶牛以确定其不同剂量对奶牛生产性能的影响.结果显示,6种组合中,组合3最好,在不同剂量组中以每天10 g量最好.