Anthelmintic treatment of dairy cows and its effect on milk production.

The results of more than 80 experiments on gastrointestinal parasitism and the impact of anthelmintic treatment on milk production in dairy cattle were reviewed. Abattoir surveys of culled dairy cows, faecal egg counts in milking cows, and serological tests and worm counts in cull cows in milk production studies were collated to assess the level of parasitism in dairy herds. The studies were divided into four general categories: induced infections in previously uninfected cattle; naturally infected cattle treated in mid-lactation; naturally infected cattle treated one to three times during the dry period and/or just before or just after parturition; and naturally infected cattle treated repeatedly from early lactation or given strategic treatments throughout the year. In most studies, the milk production of anthelmintic-treated cattle was compared with that of untreated controls. The anthelmintics investigated included members of the organophosphate, benzimidazole, imidazothiazole and macrocyclic lactone groups. The number of experiments in which the medicated (or uninfected) group had a higher milk yield was compared with the number of experiments in which the control (or infected) group had a higher yield. Overall, the studies demonstrated that grazing dairy cattle are likely to be infected with gastrointestinal nematode parasites, usually Ostertagia ostertagi and Cooperia species. These infections may be present as inhibited larvae, and a periparturient or spring rise is associated with their emergence. There is, at present, no reliable means of determining whether a cow or a herd may be parasitised subclinically at a level sufficient to interfere with milk production. In 70 of 87 experiments (80 per cent) there was an increase in milk production (P < 0.001) after anthelmintic treatment, with a median increase of 0.63 kg/day. In each of the four trial categories, a majority of the studies showed that anthelmintic treatment increased milk production. The yield of milk fat by the medicated cows was greater than by the controls in 26 of the 35 experiments in which that variable was studied (P < 0.01).     

Effect of lameness on milk yield in dairy cows

OBJECTIVE: To examine the relationship between lameness and milk yield in dairy cows. DESIGN: Cohort study. ANIMALS: 531 dairy cows. PROCEDURE: Cows affected with lameness were classified into 1 of 3 groups on the basis of type of diseases or lesions observed, including interdigital phlegmon (foot rot), papillomatous digital dermatitis (foot warts), or claw lesions. Cows not affected with lameness were classified as healthy. From Dairy Herd Improvement Association records, 305-day mature equivalent milk yield data were collected at the end of lactation or when the cow left the herd. Milk yield was compared between cows affected with lameness and healthy cows. RESULTS: 167 (31%) cows were affected with lameness during lactation. Lame cows had claw lesions (60%), papillomatous digital dermatitis (31%), or interdigital phlegmon (9%). Milk yield in lame cows with interdigital phlegmon (mean, 17,122 lb) was significantly less, compared with healthy cows (19,007 lb). CONCLUSIONS AND CLINICAL RELEVANCE: In this herd, interdigital phlegmon was associated with a 10% decrease in milk production. Lame cows with claw lesions or papillomatous digital dermatitis produced less milk than healthy cows, but the difference was not significant.     

体细胞数对牛奶品质及产量的影响

根据宁夏地区某奶牛场的DHI检测获得的体细胞数据(SCS),利用SAS软件实现单因素方差分析,探讨不同乳中SCS对产奶量和乳中主要成分的影响,并对它们之间的相关性进行分析。结果表明:乳中SCS与日产奶量呈显著负相关(P0.01);与乳糖和胎次呈正相关(P0.01);乳中SCS水平与乳脂率、乳蛋白率和尿素氮没有明显的相关性。本试验通过对SCS的研究为乳品质的测定提供一定依据和参考。     

Ketosis treatment and milk yield in dairy cows related to milk acetoacetate levels

Milk yield and milk acetoacetate (M-acac) were measured weekly for the first 6 weeks of lactation in 5 herds with a ketosis problem. Ketosis treatments and the corresponding ketotest score, were also recorded. The treatment rate was highest 7-16 days after calving. Most of these early cases were associated with low ketone levels in milk, whereas the treatment rate for cows with high ketone levels was highest 17-31 days after calving. Nearly half of the treated cows were low-ketone animals. They were classified as ketosis cases in the cow health card records, although probably suffering from other post partum disturbances in many instances. About 40% of the cows with high ketone levels recovered spontaneously. Reduction in milk yield associated with peak M-acac levels was transient and moderate. It was concluded that health card statistics overestimates the severity of the ketosis problem in Norway.     

植物甾醇对泌乳前期奶牛产奶量及乳成分的影响

根据年龄、胎次、泌乳时间和产奶量选择24头泌乳奶牛,随机分为对照组、试验Ⅰ组和试验Ⅱ组。对照组饲喂奶牛场配制的全混合饲料,试验Ⅰ和Ⅱ组每头奶牛日粮中分别添加40 g/d和80 g/d植物甾醇,研究植物甾醇对奶牛生产性能的影响。结果表明,与对照组相比,试验Ⅰ和Ⅱ组奶牛的产奶量分别提高了2.07 kg/d(5.64%,P0.05)和1.74 kg/d(4.75%,P0.05);试验Ⅰ和Ⅱ组奶牛乳脂率分别提高了8.22%(P0.01)和2.97%(P0.05);乳蛋白率分别提高了2.45%(P0.05)和1.05%(P0.05);非脂固形物分别提高了1.29%(P0.05)和0.23%(P0.05),体细胞数分别下降了37.31%和19.34%,但差异均不显著(P0.05);牛奶中乳尿素氮含量分别降低了5.29%(P0.05)和7.58%(P0.01)。结果表明泌乳前期奶牛补饲一定量的植物甾醇能够提高产奶量和改善乳成分。     

头孢氨苄治疗奶牛乳房炎的效果及在牛奶中残留规律的研究

研究通过临床确诊患乳房炎的奶牛71头,采用头孢氨苄的4种不同用药方法进行治疗,用药后观察治疗效果及检测其残留规律。结果显示:肌注头孢氨苄、肌注头孢氨苄联合肌注普鲁卡因、静注头孢氨苄、静注头孢氨苄联合乳管注入普鲁卡因4种用药方案治疗奶牛乳房炎的有效率为75%～88.9%,平均有效率为81.8%;治愈率在65%～83.3%之间,平均治愈率为74.6%。通过检测,单独用药和联合用药对残留规律的影响不大,二者差异不显著。单独肌肉注射和联合肌肉注射普鲁卡因的弃奶期分别为59、58h(2.5d);单独静脉注射、联合乳管注入普鲁卡因的弃奶期分别为56、52h,4种用药方法的弃奶期比标准规定的2d延长了12h。     

The effect of Saccharomyces cerevisiae1026 used alone or with vitamin-mineral premix on milk yield and milk composition in dairy cows

The effect of a yeast culture (Saccharomyces cerevisiae1026) added to the diet with or without supplementation with vitamin premix and mineral bioplexes on milk production responses of 30 early-lactation Black and White Lowland cows was determined in a 17-week experiment. The daily ration (DM) consisted of 55% forages and 45% concentrates. Milk yield and milk composition were only slightly influenced by the yeast culture given without premix, but combined supplementation with yeast culture and premix exerted a significant effect on milk production and composition. Cows supplied with the yeast culture produced 38 kg more milk than the controls by day 120 of lactation, whereas from cows fed yeast culture and premix an additional 150 kg of milk was obtained. In cows treated with the yeast culture alone, the total yield of milk protein, casein and lactose rose by 4.4 kg, 3.0 kg and 6.0 kg, respectively, and that increase was not significant. At the same time, the total yield of milk components increased significantly in cows fed a combination of yeast culture, vitamin premix and mineral bioplexes. The total yield of milk protein, casein and milk fat increased by 9.2 kg, 6.0 kg and 8.2 kg, respectively. The results suggest that mineral bioplexes stimulate the action of yeast culture in the rumen and the availability of nutrients in the mammary gland.     

Loss of milk yield due to Akabane disease in dairy cows

Akabane disease is an infection with clinical signs of congenital malformation and abortion in ruminants. Abnormal parturitions caused by Akabane disease result in great economic loss. The purpose of this study is to estimate the reduction in the milk yield from abnormal parturition due to Akabane disease. The data were collected from 33 Holstein cows on 11 farms. The animals had abnormal parturitions during the period from September 1998 to March 1999, and were diagnosed as having Akabane disease. The mean and standard deviation of the rate of reduction in the milk yield of 33 cows after abnormal parturition caused by Akabane disease was -11.4 +/- 14.9%. The means and standard deviations of the rate of reduction of four cows calving abnormally at 220-239 days of gestation, nine cows calving abnormally at 240-270 days of gestation, and 20 cows calving abnormally at 271-300 days of gestation were -26.6 +/- 24.7%, -14.7 +/- 11.0%, and -6.9 +/- 12.3%, respectively. In this study, we demonstrated that the rate of reduction in the milk yield in cows affected by Akabane disease was -11.4 +/- 14.9%, but values as high as -26.6 +/- 24.7% were reached in the comparison with the milk yield obtained after normal parturition.     

过瘤胃氨基酸高能复合物对奶牛产奶量及乳成分的影响

为研究不同过瘤胃氨基酸高能复合物对奶牛产奶量及乳成分的影响,试验选择胎次(3～5胎)、产奶量、产犊日期相近,体重(600±20)kg健康荷斯坦泌乳高峰期奶牛24头,随机分为4组,每组6头。1组为对照组,饲喂牛场常规日粮;2、3、4组为试验组,分别在常规日粮基础上添加过瘤胃氨基酸高能复合物Ⅰ、Ⅱ、Ⅲ500 g/(d.头)。正式期60 d。结果表明:奶牛日粮中添加过瘤胃氨基酸高能复合物后,均可明显提高奶牛产奶量、乳脂率、乳蛋白率及乳中总干物质含量。尤其是复合物Ⅲ,添加效果最为理想,平均日产奶量、乳脂率、乳蛋白率及总干物质含量分别比对照组提高21.19%(P<0.05)、21.31%(P<0.05)、9.72%(P<0.05)和10.34%(P<0.05),平均日校正乳产量提高35.70%(P<0.05)。     

日粮添加植物油籽对奶牛产奶量、乳成分及采食量的影响

本试验选择40头生产性能、泌乳日龄相近的妊娠荷斯坦奶牛，采用单因素随机区组试验设计，研究添加不同植物油籽对其生产能力及乳成分等的影响。试验结果表明添加植物油籽对产奶量影响差异不显著，但是混合油籽和膨化大豆组较对照组的产奶量有提高的趋势；添加植物油籽对乳常规成分中乳脂、乳蛋白、总固形物之间的改变差异不显著；大豆的不同加工方式对产奶量也无显著影响；添加油籽并不影响奶牛对各营养成分的采食；添加植物油籽可以提高奶牛对外界恶劣环境的抵抗力。     

Comparison of milk yield in dairy cows with different degrees of lameness

OBJECTIVE: To compare milk yield among cows classified as nonlame, moderately lame, and lame and to examine the relationship between severity of lameness and milk yield in cows classified as lame during the first 100 days after parturition. DESIGN: Longitudinal study. ANIMALS: 465 Holstein cows. PROCEDURE: Cows were examined weekly during the first 100 days after parturition and assigned a lameness score by use of a 6-point locomotion scoring system (ie, 0 to 5). Milk yield was compared among cows classified as nonlame, moderately lame, and lame. Among cows classified as lame (locomotion score > or = 4), milk yield was compared for cows with low, medium, and high cumulative locomotion scores. Cows classified as lame were further examined on a tilt table for diagnosis and treatment of lameness. RESULTS: 84 (18%), 212 (46%), and 169 (36%) cows were classified as nonlame, moderately lame, and lame, respectively. Among cows in their second or later lactations, milk yield in lame cows was significantly lower than that in moderately lame and nonlame cows. In addition, among cows classified as lame, milk yield was significantly lower in cows with high locomotion scores during the first 100 days after parturition, compared with cows with low scores. Most (58%) cows classified as lame had laminitis. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate a linear relationship between increasing degree of lameness and decreasing milk yield among cows in their second or later lactations. The locomotion scoring system used in this study may be a useful management tool that veterinarians and dairy farmers could adopt for early detection of lameness in dairy cows.     

The effect of mastitis on milk progesterone concentration in dairy cows

A within cow comparison was made between milk progesterone levels in healthy and mastitic quarters. Material was collected from cows with mastitis induced by bacterial inoculation, or by inoculation with bacterial endotoxin. Furthermore material from cows with spontaneous subclinical mastitis was used. Milk progesterone levels were lowered due to mastitis. However, the decrease was not large enough to cause misinterpretation of where in the oestrous cycle (luteal phase or non-luteal phase) the samples were taken.     

Nitrogen efficiency of dairy cows as affected by diet and milk yield

The aim of this study, which was part of the EU-financed project Life Ammonia, was to evaluate the effects of dietary components and milk production on nitrogen efficiency of dairy cows. The study included examining the effects of decreased crude protein (CP) concentration in a grass-clover silage based diet and results of mixing whole-crop barley silage (WCBS) with grass-clover silage in the diet, on feed intake, milk production and nitrogen efficiency. Rations were formulated and milk production data were registered individually each month for 42 cows of the Swedish Red Cattle breed during four indoor periods from 1999 to 2003. The range in nitrogen efficiency by the cows, 11 to 398 days in milk, was 18 to 40%, when fed a diet containing 135 to 184 g CP/kg DM, 44 to 56% of NDF as rumen degradable fibre (RDF) and milking 13 to 57 kg of ECM daily. The average CP concentration of the diet, containing mainly grass-clover silage and concentrate, was decreased from 168 g/kg DM (170 g in early lactation) in the control treatment period to 160 g/kg DM (163 g in early lactation) during the following treatment period. The CP concentration was 170 g/kg DM (171 g in early lactation) during the third treatment period, when the grass-clover silage was fed in a mixture with WCBS. Using the whole data set (n = 284 for primiparous, n = 440 for multiparous cows based on measurements each month) resulted in models, in which total DM intake, ECM yield, dietary CP concentration and RDF were the most important factors affecting nitrogen utilisation of primiparous and multiparous cows. Increases in both average DM intake and milk yield by multiparous cows and no changes in average intake and milk yield by primiparous cows fed the low CP diet or the normal CP diet containing WCBS, compared to cows fed the normal CP diet, resulted in similar nitrogen efficiencies among the treatments. Hence, dietary CP concentrations of 160 to 170 g/kg DM can be used for cows in early lactation in commercial herds to improve nitrogen utilisation without causing a simultaneous decrease in milk yield.     

Response to selection for milk yield and metabolic challenges in primiparous dairy cows

The effect of selection for milk yield on lactation yield, net energy balance, and on plasma growth hormone, insulin, prolactin, nonesterified fatty acids and glucose was studied in two groups of primiparous Holstein cows of differing genetic merit. Net energy balance was calculated and serial blood samples were collected for a 7 hr period at 0, 45, 90 and 180 days postpartum. Growth hormone releasing factor (.2 μg/kg BW) was administered after 2.5 hr at 0, 45 and 180 days postpartum, while epinephrine (.7 μg/kg BW) was administered at 90 days postpartum, Milk yield was greater, net energy balance was decreased and plasma growth hormone was greater in genetically superior selection group cows compared to control cows.

Growth hormone showed similar increases in both genetic groups in response to growth hormone releasing factor, while prolactin, insulin and glucose were not altered. Epinephrine stimulated an increase in plasma nonesterified fatty acid, glucose and insulin, but responses did not differ between genetic groups. Results indicate differences exist in production efficiency, net energy balance and plasma growth hormone concentration among dairy cattle as a result of selection for milk yield and suggest that selection pressure may act to alter homeorhetic control of nutrient metabolism.     

The effect of a single prolonged milking interval on inflammatory parameters, milk composition and yield in dairy cows

A technical stop in automatic milking systems may result in a severely prolonged milking interval (PMI) with subsequent impact on milk somatic cell count (SCC). This study investigated the inflammatory reaction, milk composition and yield during SCC peak observed in composite milk after exposing cows to a single PMI of 24h. At the first milking after the PMI, a sharply increased proportion of milk polymorphonuclear leukocytes (PMN) but marginally increased SCC were observed. The peak in SCC was not seen until morning milking day 2 after the PMI, notably, concomitantly with a decreased PMN proportion. An increase in blood lactose, milk bovine serum albumin and serum amyloid A (SAA) and a drop in milk alpha lactalbumin (ALA) were seen concomitantly with the peak in PMN. All parameters mentioned, had returned to base line after day 2. The changes in SCC and SAA had the longest duration. Lactate dehydrogenase in afternoon milk was decreased during the whole study as was also afternoon milk yield. Interleukin-1β could not be detected in milk at any time. SAA and ALA, respectively, may influence chemotaxis and the changed concentrations observed after the PMI might have contributed to the increased migration of PMN to milk.     

Analysis of correlated continuous repeated observations: modelling the effect of ketosis on milk yield in dairy cows

This study used mixed models analysis to demonstrate the advantages of a repeated measures technique for a continuous variable over a single measure technique. As an illustration, the loss of milk yield due to ketosis was studied in 2604 multiparous New York State Holstein cows belonging to eight herds, calving between 1991 and 1993. Two methods of analysis were presented: The first treated milk yield as a continuous, summary measure (projected 305-day milk yield); the second treated milk yield as repeated measurements (test-day milk yields). In the first example, with 305-day milk yield as the outcome, ketosis was treated as a binary covariate. Ketosis had no effect on the 305-day milk yield. In the second example, with monthly test-day milk yields as the outcome, four different covariance structures (simple, compound symmetry, autoregressive, and unstructured) to model the association among the repeated measurements were compared. With this approach, ketotic cows yielded significantly less milk per day both before and immediately after diagnosis than did non-ketotic cows. Based on the goodness-of-fit statistics, it was unclear whether an autoregressive or unstructured covariance structure was best. However, an autoregressive structure, in which the previous and current test-day milk yields are assumed to be correlated, was considered more suitable in this study; it is a simpler and more appropriate covariance structure for this particular problem than is an unstructured covariance structure. Nevertheless, with the test-day approach, any of these correlation structures could be used to estimate milk loss after disease. Based on these findings, it is recommended that a repeated measures approach, rather than a single measure approach, be used to study the short-term effect of disease on milk yield.     

Culling of dairy cows. Part III. Effects of diseases, pregnancy status and milk yield on culling in Finnish Ayrshire cows

The effects of 15 diseases, pregnancy status and milk yield on culling were studied in 39 727 Finnish Ayrshire cows that calved in 1993 and were followed until culling or next calving. Survival analysis, using the Cox proportional hazards model, was performed with diseases, pregnancy status and milk yield as time-dependent covariates. Effects of parity, calving season and herd were also accounted for.

Pregnancy status was the single most influential factor affecting culling decisions, followed by milk yield. Several diseases also had a significant effect on culling, the most influential ones being mastitis, lameness, teat injuries, and milk fever. The effects of all of these factors varied according to the stage of lactation.

Milk yield had a significant effect on culling decisions, depending on the stage of lactation. At the beginning of lactation, milk production did not have any effect on culling decisions, but later on, the highest producers were at the lowest risk of being culled and the lowest producers had the highest risk. Adjusting for milk yield modified the effects of parity, most diseases and also pregnancy status on culling. Effects of parity increased after including milk yield in the model, indicating that milk yield and parity are interrelated in their effects on culling. The effects of pregnancy status also increased towards the end of lactation when milk yield was accounted for in the model. The effects of mastitis, teat injuries and lameness decreased after adjusting for milk production. These diseases lower milk yield and thus, part of their effect on culling was mediated through milk production. The effects of anestrus and ovarian cysts were mainly modified by pregnancy status, but not by milk yield. The effects of milk fever on culling increased at the beginning of lactation after including milk yield in the model. This suggests that even though cows with milk fever tend to be higher producers, it is the disease as such that triggers the culling decision early in the lactation. The changes in the effects of other diseases after adjusting for milk yield varied, depending on the disease and the stage of lactation.     

苜蓿添加量对高产奶牛泌乳性能和乳成分的影响

30头2～4胎的荷斯坦奶牛随机分为3组,各组产奶量、体质量、胎次和泌乳天数（DIM）差异不显著。3组奶牛日粮中苜蓿干草的添加量分别为2（对照）、4和6kg,相应的日粮干物质（DM）中粗蛋白含量分别为15．6％、17．2％和18．8％,各组间中性洗涤纤维（NDF）和产奶净能（NEL）含量相同,分别为37．4％和6．9MJ／kgDM。结果表明,在以苜蓿干草为主的奶牛日粮中提高粗蛋白含量能显著提高产奶量（P〈0．05）;干物质采食量（DMI）变化不显著（P〈0．05）,但有增加的趋势;乳脂率、乳蛋白、乳糖及干物质含量没有显著变化（P〈0．05）,在奶牛日粮中大量使用苜蓿干草并不增加日粮成本,可大幅度提高经济效益,6kg组与对照相比纯增效益最高。苜蓿干草在奶牛日粮中的适宜添加量为6kg。