The effect of subclinical ketosis in dry cows on the composition of the colostrum and on health indicators in newborn calves

Subclinical ketosis of dry cows was studied as to its effect on the composition of colostrum and on the health condition and selected clinico-biochemical parameters in the new-born calves of these cows. The experimental group consisted of eight cows with ketonuria and their calves. The control group consisted of six cows without ketonuria and their new-born calves. Calves of both groups were reared in similar conditions. Colostrum samples were taken from the first milking and then from the milking 24 hours after parturition. The blood of the calves was sampled before the intake of colostrum and 24 hours after birth. The concentration of ketone bodies, particularly beta-hydroxybutyrate, was much higher in the colostrum of both groups of cows than in the blood (62.6 mg total ketone bodies per 1 litre of the first colostrum of the cows of the experimental group). The concentration of ketone bodies slightly increased after parturition. The cows with ketonuria secreted into colostrum a larger amount of oxidated ketone bodies. Colostrum quality was good in both groups. Decreased viability was not recorded during the clinical examination of the calves after birth. The level of total ketone bodies in the blood of pre-colostral calves in the experimental group was 10.4 mg per litre (a much lower concentration than in blood of their dams), and exhibited no appreciable change after taking in the colostrum. The blood of calves born to cows with ketonuria contained significantly higher amounts of oxidated ketone bodies. No correlation was demonstrated between the contents of ketone bodies in the blood of cows, in the blood of calves, and in the colostrum. The calves of the experimental group were found to have a significantly higher AST activity in plasma, as compared with the control group. Twenty-four hours after birth, the quantity of immunoglobulins in the blood serum was significantly lower in the calves of the experimental group. Thanks to good attendance and hygiene, the morbidity did not increase and no losses occurred.     

The effects of genotype and selected environmental factors on colostrum production and intake in cattle

The aim of this study was to determine effects of genotype and selected environmental factors on colostrum production, intake, and efficiency in the cattle. The investigations were conducted on 67 dam-calf pairs. All cows were of Polish Holstein-Friesian breed, the Black-and-White variety (PHF-HO), whereas calves were sired by bulls of the following breeds: PHF-HO, Polish Holstein-Friesian of the Red-and-White variety (PHF-RW), Jersey (JE), Montbéliarde (MB) and Limousine (LI). The colostrum was collected from cows and offered to calves "from bucket" thrice a day. The amount of produced colostrum considerably exceeded the ability of its consumption by calves. Low share of HF genes in the cow, older cow's age and calving in the period from January to April appeared to be favorable factors for colostrum production. Calves born to cows with low HF gene share drank more colostrum than calves originating from cows with higher gene share of this breed. Crosses with JE drank the highest amount of the colostrum in relation to body weight, while MB-sired calves drank the highest amount in absolute terms. Colostrum intake was positively correlated with the dam's age. Furthermore, it was shown that in case of the first colostrum intake the most favorable period was from May to September, while in cases of total intake in the first day of life and mean intake in the first 5 days of life it was the period from January to April. Crosses with JE were characterized by extremely high use of colostrum per unit of body weight gain.     

安格斯母牛初乳产量与质量测定及其新生犊牛被动免疫效果评价

【目的】 新生犊牛被动免疫转移失败（failure of passive transfer,FPT）会导致犊牛发病率和死亡率显著增高,影响后期生长发育。本试验针对国外引进的安格斯母牛初乳产量和质量进行测定,并对其新生犊牛被动免疫效果进行评估,以期为新生犊牛初乳管理措施制定提供科学依据。【方法】 随机选择健康安格斯初产母牛（24月龄）和经产母牛（36~48月龄）各15头,待母牛产犊后立即进行人工挤奶测定初乳产量、营养成分及免疫球蛋白浓度。选取初产和经产新生犊牛各15头,测定其初生重,分别采集犊牛出生后未食初乳（0 h）和食初乳后（24~36 h）血样,测定其血清总蛋白含量及各生理生化指标。【结果】 初产母牛平均初乳产量极显著低于经产母牛,但其初乳中乳蛋白、非脂乳固体、乳糖、灰分含量,以及密度和电导率均极显著高于经产母牛（P<0.01）。初产母牛和经产母牛初乳中免疫球蛋白浓度分别为28.72%和26.24%,合格率分别为93.33%和91.67%,差异均不显著（P>0.05）;初产和经产新生犊牛被动免疫失败率分别为33.3%和25.0%;初产新生犊牛平均初生重极显著低于经产新生犊牛（P<0.01）;被动免疫成功犊牛平均初生重和球蛋白含量均极显著高于被动免疫失败犊牛（P<0.01）。【结论】 新疆安格斯犊牛FPT的主要原因可能是母牛初乳产量低导致新生犊牛初乳摄入不足,初生重较低的犊牛FPT的风险性较高。本研究为制定切实可行的新生安格斯犊牛初乳补饲计划提供了科学基础。     

The supply of newborn camel foals (Camelus dromedarius) with immunoglobulin G

A major problem in camel breeding in East Africa is the high mortality rate of young camel calves. The purpose of this research was to examine the quality of camel colostrum and extent of the calves passive immunization by maternal antibodies. In 31 camel birth on a ranch in Kenya, IgG concentrations in the colostrum and in the serum of the calf during the first three days of life were measured. IgG concentration in the serum of the calf reaches a maximum 24 hours after birth. In 39% of the examined calves, this maximum concentration was below 4 g/l. In 61% of the calves, an IgG concentration of more than 4 g/l was reached. No correlation was found between diseased animals and the IgG concentrations in the serum of the calves involved. A minor IgG concentration can be excluded as a reason for calves mortality. The high percentage of insufficient IgG concentration in the serum of the calves therefore must be caused by insufficient intake of colostrum. Future measures in order to decrease calves mortality must therefore try to improve the management of calves, especially the sufficient intake of colostrum.     

Comparison of three methods of feeding colostrum to dairy calves

Absorption of colostral immunoglobulins by Holstein calves was studied in 3 herds in which 3 methods of colostrum feeding were used. Failure of passive transfer, as determined by calf serum immunoglobulin G1 (IgG1) concentration less than 10 mg/ml at 48 hours of age, was diagnosed in 61.4% of calves from a dairy in which calves were nursed by their dams, 19.3% of calves from a dairy using nipple-bottle feeding, and 10.8% of calves from a dairy using tube feeding. The management factor determined to have the greatest influence on the probability of failure of passive transfer in the herds using artificial methods of colostrum feeding (bottle feeding or tube feeding) was the volume of colostrum fed as it affected the amount of IgG1 received by the calf. In dairies that used artificial feeding methods, failure of passive transfer was infrequent in calves fed greater than or equal to 100 g IgG1 in the first colostrum feeding. In the dairy that allowed calves to suckle, prevalence of failure of passive transfer was greater than 50% even among calves nursed by cows with above-average colostral IgG1 concentration. Analysis of the effect of other management factors on calf immunoglobulin absorption revealed small negative effects associated with the use of previously frozen colostrum and the use of colostrum from cows with long nonlactating intervals.     

Health status and risk factors associated with failure of passive transfer of immunity in newborn beef calves in Québec

Risk factors associated with failure of passive transfer of immunity (FPT) were evaluated among newborn beef calves in Québec. Physical examination was performed on calves born of a normal calving and blood samples were collected for determination of health status and measurement of serum concentration of immunoglobulin (Ig) G1. Of 225 calves, from 45 herds, 19% showed FPT (serum IgG1 concentration < 10.0 g/L). Calves born in a stanchion-stall were more likely to show FPT (OR: 10.2). Calves bottle-fed colostrum were less at risk for FPT (OR: 0.06). Calf gender, month of birth, dam parity, and dam body condition score were not associated with FPT. No association was detected between FPT and health status. Special care should be given to calves born from cows in a stanchion-stall to ensure adequate colostrum intake. Failure of passive transfer of immunity should be considered with other risk factors when investigating morbidity.     

Effect of colostrum intake on diarrhoea incidence in new-born calves

In a survey which lasted one year and included data of 73 dairy cows with their calves, colostrum immunoglobulin G (IgG) of 22 primiparous cows and serum IgG of their calves were lower than the corresponding IgG levels of 51 multiparous cows and their calves. Serum IgG concentration was not correlated with diarrhoea incidence. Although there were no seasonal differences in the IgG concentration of colostrum and calf serum, neonatal diarrhoea incidence was higher in calves which were born in winter than in calves which were born in summer (P < 0.01). Thus the high diarrhoea incidence in winter was not a consequence of an insufficient IgG transfer to the calves. The 60 calves of the second study were fed colostrum on the first day of life. From the second to the tenth day 28 experimental calves received milk and 0.5 l of surplus colostrum of the first and second milking twice a day, whereas 32 control calves received milk only twice a day. Two of the 28 experimental and 11 of the 32 control calves suffered from diarrhoea during the first ten days of life (P < 0.05). These results show that the ingestion of surplus colostrum in addition to milk after the first day of life protects the new-born calf against infectious diarrhoea.     

Selected indicators of colostrum quality in cows over the period of a year

Under the conditions of large-scale breeding, seasonal changes in the total protein of colostrum whey, gammaglobulins, vitamins A, E, C, and carotene in cow's colostrum from the first milking, were studied in the course of the first 12 months. As indicated by the results of an analysis of 302 colostrum samples, the concentrations of total protein in whey were significantly higher in winter (P less than 0.01) than in the summer season. On the other hand, vitamin C levels were higher in summer than in winter. A lower level of total protein of colostral serum than the required minimum of 120 g per litre was recorded in 64.4% of the cows. A highly positive correlation (r = +0.981) was demonstrated between the concentration of total protein and gammaglobulins in colostrum whey. This fact makes it possible to consider and use for diagnostic purposes the total protein of whey as a sufficiently exact parameter of colostrum quality without having to determine the gammaglobulin level. On the basis of these analyses it is possible to some extent not only to evaluate the health condition of high-pregnant cows and the quality of attendance, but also to prognosticate the health of their calves.     

Experimental use of gamma globulin preparations and their effect on serum immunoglobulin levels in calves

The saturation effect of a serum and colostrum immunoglobulin preparation on the humoral immunity system of calves was studied during the first days after birth. The positive effect of the preparations depended on the dose and on the immunity level acquired through colostrum. The serum immunoglobulin preparation was used at three doses (1.2 ml, 1.6 ml, 2.2 ml per kg live weight). In the calves suffering from hypogammaglobulinaemia, a significant saturation effect was recorded only at the dose of 2.2 ml per kg live weight. This dose represented an amount greater by up to 79% than the recommended maximum therapeutic dose. The administration of the recommended dose of the colostral immunoglobulin preparation (20 ml per calf) positively influenced the concentration of serum immunoglobulins in 26% of the test calves, but these suffered from hypogammaglobulinaemia. In none of the cases of calves with a normal level of gammaglobulins and calves with diarrhoea was an increase in the concentration of serum immunoglobulins recorded. An increase in the concentration of serum immunoglobulins in the calves after the administration of the above mentioned preparations was so small that it appears impossible to use them in the saturation therapy in calves affected by hypogammaglobulinaemia and agammaglobulinaemia. Some of the mechanisms of the action of gammaglobulin preparations are discussed for the cases where the results of the administration of the preparations were positive.     

Humoral immune response of water buffalo monitored with three different antigens of Toxocara vitulorum

Humoral immune response of water buffalo naturally infected with Toxocara vitulorum was monitored using three different antigens of this parasite in serum and colostrum of buffalo cows and calves. Soluble extract (Ex) and excretory/secretory (ES) larval antigens and perienteric fluid antigen (Pe) of adult T. vitulorum were used to measure the antibody levels by an indirect ELISA. Serum of 7-12 buffalo cows for the first 365 days and colostrum of the same number of buffalo cows for the first 60 days of parturition, and serum of 8-10 buffalo calves for the first 365 days after birth were assayed. The ELISA detected antibodies against all three T. vitulorum antigens in the colostrum and serum of 100% of buffalo cows and calves examined. The highest antibody levels against Ex, ES and Pe antigens were detected in the buffalo cow sera during the perinatal period and were maintained at high levels through 300 days after parturition. On the other hand, colostrum antibody concentrations of all three antigens were highest on the first day post-parturition, but decreased sharply during the first 15 days. Concomitantly to the monitoring of immune response, the parasitic status of the calves was also evaluated. In calves, antibodies passively acquired were at the highest concentrations 24 h after birth and remained at high levels until 45 days coincidentally with the peak of T. vitulorum infection. The rejection of the worms by the calves occurred simultaneously with the decline of antibody levels, which reached their lowest levels between 76 and 150 days. Thereafter, probably because of the presence of adults/larvae stimulation, the calves acquired active immunity and the antibodies started to increase slightly in the serum and plateaued between the days 211 and 365. All three antigens were detected by the serum antibodies of buffalo calves; however, the concentration of anti-Pe antibody was higher than anti-EX and anti-ES, particularly after 90 days of age. By conclusion, the buffalo cows develop immunity and keep high levels of antibodies against T. vitulorum-Ex, ES and Pe antigens and these antibodies are transferred to their calves through the colostrum. This passively acquired immunity does not protect the calves against the acquisition of the infection, but these antibodies, passively or actively acquired, may have an important role during worm rejection by the calves and prevention of intestinal reinfection.     

Colostrum quality,IgG absorption and daily weight gain of calves in small-scale dairy production systems in Southern Vietnam

Dairy production is expanding rapidly in Vietnam, but still, the smallholder farms are most common. The aim of this study was therefore to get improved knowledge about colostrum quality in dairy cows, immunoglobulin G (IgG) absorption, daily weight gain in dairy calves and calf management in small-scale dairy production systems in Southern Vietnam. A field survey was conducted on 40 farms, with two calves on each farm being intensively studied. It was observed that newborn calves were separated from their dams immediately after birth and offered 2–4 L first colostrum within 4 h by bucket feeding. The first colostrum IgG level, fat and protein content were on average 35.6, 4.8 and 21.4%, respectively, and 91% of the cows produced colostrum of good quality (Brix value >22%). The IgG level in serum of calves, measured as Brix value, was on average 9.3%. Colostrum in the samples studied was of quite high quality and on-farm observations showed that colostrum was offered on the first day of calf life, so passive transfer of immunity to the calves was high. In total, 10% of the calves had a Brix value for IgG in serum lower than 8.3%, indicating that those calves had suffered from failure of passive immune transfer (FPT). The daily weight gain of female and male calves was 0.75 and 0.54 kg, respectively. Serum IgG was positively correlated with colostrum protein (P = 0.002). Daily weight gain and diarrhoea was negatively correlated (P = 0.001).     

Absorption of colostral immunoglobulins and its interdependence

Three main factors underlying the immunity state of newborn calves are evaluated. During the absorption of colostral immunoglobulins the immunoprotein profile of a newborn calf is influenced by the following factors (arranged according to importance): volume of the first colostrum taken in, time of the first drinking, and immunoglobulin concentration (IgG and IgM) in colostrum. When given 1.1 or 2.0 litres of colostrum of about the same quality (as to immunity), the calves of the compared groups had significantly different levels of total serum Ig measured 24 hours after birth: 10.7 and 18.6 U ZST (P less than 0.05) and 48 hours after birth: 11.7 and 19.7 U ZST (P less than 0.01). A significant difference in total serum proteins was observed only in the 48th hour post partum (54.4 and 63.6 g per litre; P less than 0.05). At the intake of 1.5 litres of colostrum within two and five hours after birth, with the same total intake of the sum of IgG and IgM in the groups, the calves exhibited, in the 24th hour, total serum Ig levels of 14.4 and 12.4 U ZST (P greater than 0.05) respectively, and 56.0 and 47.9 g per litre (P greater than 0.05) of total serum protein, respectively. With a different concentration of colostral IgG (122.0 or 77.0 g per litre) the statistically significant Ig absorption into blood was adequately different (17.2 and 10.0 U ZST, respectively, P less than 0.05). The differences in the concentration of total serum Ig and total proteins between the 24th and 48th hour after birth were only very small and statistically insignificant. Regression analysis proved a significant relation (P less than 0.01) between the level of total serum Ig 24 and 48 hours after birth and the total amount of IgG and IgM taken in with the first colostrum. The calves coming from primiparae had a lower immunity (P less than 0.01) in comparison with the calves of multiparae. A similar relation in the absorption of colostral Ig was observed when the spontaneously born calves were compared with those born by the Caesarean section (P less than 0.01).     

Lysozyme in the colostrum and blood of calves and dairy cows

During examination of lysozyme concentration we have found out that 90.3% of calf sera had the lysozyme concentration to 0.5 microgram . ml-1, 5.7% of sera showed zero values and only 4.0% of sera values from 0.5 to 1.4 microgram . ml-1. A higher lysozyme content was recorded in sera of calves up to the age of ten days in comparison with sera of calves after the second week post natum. The lysozyme concentration showed in calves a two-phase increase in the age dynamics up to the seventh to eighth week of life with a peak in second and fifth to eighth week of age. The increase rate in the first phase and the time onset of increase in the second phase were in negative, and/or positive relation to the level of immunity obtained through colostrum. The lysozyme concentration in serum of dairy cows was on fourth day post partum as much as ten times higher than in serum of their progenies 48 hours after parturition. In first colostrum the lysozyme concentration fluctuated within the range of 0.15 to 0.65 microgram X ml-1, with an average of 0.30 microgram X ml-1. The concentration of lysozyme and immunoglobulins of the IgG and IgM class in colostrum showed a contrary trend in first and second milk yield, with a tendency towards increase for lysozyme and towards decrease for immunoglobulins.     

Colostrum intake by dairy calves

AIMS: To determine which clinical parameters could be used to identify calves with low serum immunoglobulin levels and to examine the influence of cow and calf behaviour on colostrum intake. METHODS: Blood samples were taken from 74 dairy calves after they were separated from their dams, and analysed for serum gamma glutamyltransferase (GGT) activity. Physical and behavioural measurements were taken for 57 of these calves at this time. The behaviour of 2 1 dairy cows and their calves was observed between birth and the time the calves were separated when a blood sample was taken from 17 of them and analysed for GGT. RESULTS: Low serum GGT activities (below 200 U/l GGT), indicating low serum immunoglobulin levels, were found in 45% of the group of 74 calves. The calves which had not received colostrum were not easy to distinguish from those that had on the basis of physical or behavioural features. The amount of time that the 2 1 calves spent with their dams before being separated ranged from 1.2 to 24.9 hours. Thirty-three per cent of these calves had not sucked within this time. Of the calves that did suck, 79% did so within 6 hours of birth. CONCLUSIONS: About one half of New Zealand dairy calves may not receive colostrum from their dams even when they are together for up to 24 hours. Most calves that are going to suck of their own accord will do so within 6 hours of birth. CLINICAL SIGNIFICANCE: Dairy calves should be removed from their dams after 6 hours and fed colostrum to guarantee that they receive sufficient immunoglobulins.     

Calf and colostrum management practices on New Zealand dairy farms and their associations with concentrations of total protein in calf serum

AIMS: To gather information on management practices and farmer attitudes to management of cows and calves during the immediate post-partum period on dairy farms in New Zealand, and to assess these practices for associations with concentrations of total protein (TP) in serum of calves 1–8 days-old.

METHOD: Between July and September 2015 blood samples were collected from calves aged between 24 hours and 7 days, from dairy farms (n=105) in nine areas in New Zealand, on three occasions throughout the calving period. Concentrations of TP were determined in all serum samples. At each visit technicians collected 1?L of the pooled colostrum that was intended for feeding to newborn calves that day. These samples were assessed for Brix, coliform and total bacterial counts. After the last sampling visit, the calf rearer or farm manager were asked to complete a questionnaire describing calf and colostrum management practices on the farm. Potential farm-level variables associated with concentrations of TP in serum of sampled calves were identified using univariable and multivariable linear mixed models.

RESULTS: Mean concentration of TP in serum of calves across all farms was 59.8 (95% CI=59.4–60.2) g/L, and was associated with region and herd size in the final multivariable model. Concentrations of TP were lower in calves from farms in Otago (56.2 (95% CI=53.4–58.9) g/L) and Southland (56.9 (95% CI=54.1–59.7) g/L) compared to calves on farms in the Far North (62.6 (95% CI=59.8–65.3) g/L), and were lower in calves from farms with a herd size >600 (58.3 (95% CI=56.7–59.8) g/L) than ≤600 (61.3 (95% CI=60.1–62.5) g/L) cows. After accounting for fixed effects, farm accounted for only 8.4% of the unexplained variation. There was no association between any of the measures of colostrum quality and concentrations of TP in serum (p>0.2).

CONCLUSION AND CLINICAL RELEVANCE: Very few herd-level variables were associated with concentrations of TP in serum. Risk factors that have been shown to be of importance in previous studies outside New Zealand were not identified as important in the current study. It is possible that, in the situation where calves are kept at pasture with their dams for prolonged periods, variables which influence how well a cow can feed its calf in the first 12–24 hours have a larger influence on concentrations of TP in serum than the collection and management of calves once they reach the rearing shed.     

Effect of enhancing curd formation during the first colostrum feed on absorption of gamma glutamyl transferase by newborn calves

OBJECTIVE: To examine the effects of curd formation within the abomasum, on the absorption of gamma glutamyl transferase (GGT) from colostrum in newborn calves. DESIGN: An in vivo physiological study with controls, and in vitro examination of calf abomasal fluid. PROCEDURES: Newborn calves were taken from cows without allowing them to suckle. They were fed either 1.5 kg colostrum or 1.5 kg colostrum plus rennet, with intervals between calving and colostrum feeding ranging from 0.4 to 12.7 h. Absorption of proteins from the whey component of colostrum was assessed from the rise in activity of serum GGT. In in vitro studies, colostrum was incubated with bovine amniotic fluid, newborn calf abomasal fluid or newborn calf forestomach contents, with or without rennet, to test the curd inhibiting effects of components in the abomasal fluid of newborn calves. RESULTS: In vivo: addition of rennet to the colostrum feed reduced the proportion of calves with serum GGT activity below 500 U/L by 60%. In vitro: 43% of newborn calves lacked curd forming activity in their abomasal fluid, and that deficiency was corrected by adding rennet to the incubation medium. CONCLUSIONS: Some calves are born with low amounts of curd forming enzyme activity in the abomasum. This may compromise their ability to absorb large whey proteins from the first feed of colostrum. Adding rennet to the first colostrum feed may improve passive immunity in those calves.     

母牛舔舐对新生犊牛行为及血清应激和免疫指标的影响

本试验旨在研究母牛舔舐对新生犊牛行为及血清应激和免疫指标的影响。选取30头初生重相近的健康荷斯坦母犊牛,依据其出生后被母牛舔舐的时长分为2组,每组15头。对照组(Con组)犊牛出生后仅被舔舐几下或没被舔舐,舔舐组(Lick组)犊牛出生后被舔舐15~20 min。录像记录犊牛被舔舐之后24 h的行为,检测犊牛被舔舐之后0和24 h血清应激激素和免疫相关细胞因子含量。结果表明:1)Lick组犊牛进入犊牛舍后初次成功站立用时有低于Con组的趋势(P=0.056),Lick组犊牛进入犊牛舍后在初次尝试站立至成功站立期间的尝试站立次数有低于Con组犊牛的趋势(P=0.094),Lick组犊牛初次尝试站立至成功站立用时显著短于Con组(P<0.05)。2)Lick组犊牛采食初乳时站立时长占总采食时长的比例有高于Con组的趋势(P=0.068),Lick组犊牛躺卧时长占总采食时长的比例有低于Con组的趋势(P=0.068)。3)采食初乳前后,Lick组犊牛站立时长和次数显著高于Con组(P<0.05),躺卧时长显著低于Con组(P<0.05),行走时长和次数显著高于Con组(P<0.05),探索时长有高于Con组的趋势(0.05≤P<0.10),探索次数显著高于Con组(P<0.05)。4)被舔舐之后0 h,Lick组犊牛血清皮质醇含量显著低于Con组(P<0.05)。在被舔舐后24 h,Lick组犊牛血清白细胞介素-2含量有低于Con组的趋势(P=0.097),白细胞介素-6含量显著低于Con组(P<0.05)。综上所述,母牛分娩后对新生犊牛进行15~20 min的舔舐可以降低犊牛的应激水平,增强新生犊牛的活力,同时使犊牛更为活跃。     

Effects of colostral antibody on susceptibility of calves to Cryptosporidium parvum infection

Effects of colostral antibody on susceptibility of calves to Cryptosporidium parvum infection were examined. Six calves were fed pooled colostrum that contained C parvum antibody, 6 times daily (at 4-hour intervals) for 7 days and then milk replacer for 7 days. Colostrum was obtained from healthy cows or cows inoculated parenterally with C parvum oocysts before parturition. Antibody content was determined in serum and colostrum whey, using an ELISA for anticryptosporidia immunoglobulin. Six calves were fed colostrum from healthy cows 1 time, and then milk replacer 6 times daily for 14 days. On day 1, all calves were challenge exposed with C parvum, PO, and were monitored daily for diarrhea and oocyst shedding. Bovine colostrum containing specific antibody to C parvum, at ELISA titers up to 10,240, was not effective in protecting calves against challenge exposure to C parvum.     

Plasma vitamin A status in calves fed colostrum from cows that were fed vitamin A during late pregnancy

Calves are born vitamin A and β‐carotene deficient and the β‐carotene conversion to vitamin A is limited. Colostrum, contains relatively large amounts of vitamin A and β‐carotene and the retinol and β‐carotene status of calves can be normalized with colostrum consumption. We studied whether vitamin A supplementation of cows during late gestation (dry period) increases cow plasma retinol concentrations, the retinol content of first colostrum, and the plasma vitamin A status of calves during their first month of life. Both plasma and colostrum retinol concentrations were higher in vitamin A supplemented cows than in non‐supplemented cows. In calves that were for 5 days fed colostrum (milk) from vitamin A‐supplemented cows and then mature milk, plasma retinol concentrations were higher from 14 to 30 days after birth than in calves that were fed colostrum (milk) from cows that were not vitamin A supplemented. The study shows that vitamin A supplementation of cows during the dry period can improve the vitamin A status of their calves up to 1 month, if calves ingest their colostrum/milk for up to 5 days.     

Passive protection of calves against experimental infection with Salmonella typhimurium

Cows were vaccinated with formalin-killed Salmonella typhimurium approximately seven weeks and two weeks before parturition to investigate whether passive immunity could protect their calves against experimental S typhimurium infection. After birth the calves were left with their dam for 48 hours and then separated and fed cold, stored colostrum from their own dam for a further eight days. Oral challenge five days after birth with 10(8) S typhimurium did not result in the death of these calves even when they had absorbed little colostrum. Mortality was reduced to 22 per cent in calves which sucked from vaccinated dams and were then fed colostrum from unvaccinated cows and to 50 per cent in calves born to unvaccinated cows and later fed colostrum from vaccinated animals. Calves which sucked from a vaccinated dam and then received stored colostrum from the same cow excreted salmonellas for significantly shorter periods after challenge and were less often infected at necropsy 28 days after inoculation. Protection was not correlated with the levels of O or H agglutinating antibodies in serum, which were at a maximum 24 hours after sucking and then slowly declined. There was no evidence of an active antibody response in the serum. Measurement of the O and H response of cows after vaccination indicated that the vaccination schedule could be improved. The highest levels of agglutinating antibody were measured between two and three weeks after the first vaccination and there was only a minimal response to the second vaccination before parturition.(ABSTRACT TRUNCATED AT 250 WORDS)