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1.
Fluoride intoxication in dairy calves   总被引：2，自引：0，他引：2  
Chronic fluoride intoxication in dairy cattle, caused by feeding fluoride contaminated commercial feed, was previously described in a dairy herd. Dental fluorosis and a catastrophic decrease in milk yield were the foremost findings. In calves born to the fluoride intoxicated cows, congenital fluorosis was manifested by brown discoloration of enamel, enamel hypoplasia, brown mottling of bone, severe retardation of cartilage cell differentiation, atrophy of osteoblasts, osteopenia, atrophy of bone marrow cells, serous atrophy of bone marrow fat and severely stunted growth.  相似文献   

2.
The effects of fluoride ingestion (3.5 mg/kg of body weight) were evaluated in 9 ewes at 6 through 9, 10 through 13, or 14 through 17 months of age (3 ewes/age group). In the 3 groups, the plasma fluoride concentration rapidly increased to 0.45, 0.46, and 0.50 microgram/ml, respectively, and decreased rapidly to 0.1 microgram/ml after fluoride was removed from the ration. In 5 of the 9 ewes, this short-term exposure caused symmetrical, moderate damage to the molars, which is characteristic of fluorosis in sheep. In 7 of the 9 ewes, abnormal gaps were found between incisors, which are not characteristic of fluorosis in sheep. Fluoride accumulation was higher in the roots of the incisors and in the dentine of the molars and was particularly evident in teeth that were developing when fluoride was administered; however, the fully developed teeth and teeth that developed several months after administration of fluoride also were affected. The increase in fluoride concentration in the enamel was confined to a maximum of 2 molars. The abnormal wear of the molars was not directly linked to fluoride accumulation.  相似文献   

3.
Vertical transmission of bovine leukemia virus (BLV) and bovine immunodeficiency virus (BIV) was investigated in five dairy cattle herds in Hokkaido, where 36.1 and 17.0% of cattle were BLV and BIV seropositive, respectively, and 9.9% of dams were co-infected with both BIV and BLV. Twenty six cases of offspring born from dams infected with only BLV (17 cases) or with both BIV and BLV (9 cases) were examined for the presence of BLV and BIV before and after colostrum feeding by polymerase chain reaction (PCR) and syncytium assay. After birth, all calves were separated immediately from their dams. The offspring born from BLV-positive dams were BLV-negative before colostrum feeding, suggesting that no transplacental transmission had occurred. Thereafter, these offspring were fed colostrum or milk from their dams, but still remained BLV-negative. The other offspring born from BLV-positive dams were fed with BLV-negative colostrum, or with pasteurized BLV-positive colostrum. All these calves remained negative for BLV infection, suggesting that in utero transmission of BLV is negligible. In the case of offspring born from dams co-infected with BLV and BIV, calves were BIV-positive before colostrum feeding at 1 day after the birth, indicating in utero transmission of BIV. After colostrum feeding from their dams, newborn calves became BLV-positive. In addition, one calf was BLV-positive even before colostrum feeding. These results suggest that BIV can be transmitted to offspring in utero, and that BLV can be transmitted through colostrum or milk if dams are infected with both BIV and BLV.  相似文献   

4.
Bovine dental fluorosis: histologic and physical characteristics   总被引：2，自引：0，他引：2  
Incisor teeth from 5- to 6-year-old Holstein-Friesian cattle maintained on a ration averaging 40 ppm F annually from 4 months of age were analyzed by a variety of histologic techniques. These techniques included photomicroscopy, microradiography, protein staining, and microhardness testing. The features of fluorotic enamel that were noted were: hypomineralized outer enamel, coronal cementum hyperplasia, disrupted subsurface pigment band, hypoplastic pits, puckered incremental lines, periodic radiolucent regions, positive protein staining, and decreased microhardness of the outer enamel. These results were similar to the lesions of dental fluorosis observed in other species, and explain the external appearance of fluorotic bovine teeth observed under field conditions.  相似文献   

5.
Chronic fluoride toxicity in the form of osteo-dental fluorosis was observed in cattle, buffaloes, sheep and goats from 21 villages of Banswara, Dungarpur and Udaipur districts of Southern Rajasthan where the mean fluoride concentration in drinking water varied from 1.5 to 4.0 ppm. The prevalence of dental fluorosis in calves (<1 year age) was greater than that in adult cattle and buffaloes. At a fluoride concentration in the water of 4.0 ppm, 100% of calves, 65.6% of buffaloes and 61.0% of cattle were found to be affected with dental fluorosis to varying degrees. In the older group of buffaloes, their teeth were brownish black instead of creamy yellow as found in calves and cattle. Out of 780 goats and 564 sheep, none revealed evidence of osteo-dental fluorosis. The overall prevalence of skeletal fluorosis was 8.5%, with the highest prevalence of 29.0% in cattle and 37.5% in buffaloes at a fluoride concentration of 3.2 ppm. None of the calves were affected with skeletal fluorosis. Intermittent lameness was observed in the older group of animals (>7 years age) at 2.8 ppm fluoride or more in the water. None of the fluorotic animals exhibited any apparent evidence of hypothyroidism, stunted growth or low milk production. There was no correlation between gender and the prevalence of fluorosis, but the prevalence and severity of skeletal fluorosis increased with increasing fluoride concentration and age. Possible factors causing variation in fluorosis in the cattle and buffaloes in villages with identical fluoride concentrations are discussed.  相似文献   

6.
The effects of feeding supplementary dietary copper to a herd of 400 beef cows, were studied over a two year period. In the first year of the trial, the calves showed clinical signs of copper deficiency. There was improved growth following subcutaneous injection of copper ethylenediamine tetraacetate, and the treated calves had a 2.8% increase in adjusted weaning weights. In the second year of the trial pregnant cows were fed a basal ration of bromegrass silage, barley and minerals over the winter feeding period. The feed was supplemented with copper so that half received 5.5 mg/kg of copper on a dry matter basis and half 40 mg/kg. Calving occurred in the spring and half the calves were treated with injectable copper at birth and again at 12 weeks of age. There was no evidence of copper deficiency in the calves and there was no effect of high level copper supplementation on calf birth weight, or neutrophil candidacidal activity. Susceptibility to diarrhea varied in a complex fashion; morbidity was lowest in calves born to dams fed supplementary copper and highest in calves born to supplemented dams and injected with copper at birth. The cows and calves grazed the same copper deficient pasture over the summer. The average daily gain for calves born to supplemented cows was 0.999 +/- 0.010 kg/day (x +/- SEM) which was significantly greater than the 0.972 +/- 0.009 kg/day for calves from nonsupplemented dams (p = 0.044). The benefit of copper supplementation on 200 day weaning weight was estimated at 4.8 kg. Evidence of copper deficiency was seen when a herd test showed mean serum levels below 9 mumol/L and liver values below 0.09 mmol/kg wet matter.  相似文献   

7.
Fluorotic lesions have been studied in cows and calves of SRB breed on farms belonging to 2 agricultural companies. From the one company (HP) in Dalecarlia 3 calves, 4 heifers and 2 cows were examined and from the other (B) in Södermanland 12 bull-calves. The submitted material consisted of a carcase from 1 dead calf and skull, metacarpus and in some cases kidneys from slaughtered animals. The fluorine content of feed and water samples was determined. In material from HP extensive enamel defects and strong wear were found in the deciduous incisors. Fluorotic lesions in calves have not been described previously. One calf had strong osteoporosis and in the rest of the material osteosclerosis and subperiosteal bone apposition was found. In the kidneys some tubular atrophy was found. Kidney lesions have not been observed previously in bovine fluorosis. Dark furrows and enamel defects appeared in the teeth of the heifers and the cows. In the skeleton they had osteosclerosis and in some cases also subperiosteal bone appositions. The fluorine content of the skeleton varied between 500 and 3,100 p.p.m. in bone ash. Water samples contained 0.5–2.0 and the mineral supply 500–630 p.p.m. of fluorine.In material from company B widespread enamel defects, strong wear of the deciduous incisors and deviations and irregular eruption of the permanent incisors were found. In the skeleton osteosclerosis and subperiosteal bone apposition and in the kidneys in 1 case patchy atrophy of the tubules were found. Microscopically the skeleton showed signs of repair. The fluorine content of the skeleton varied between 135 and 300 p.p.m. in the ash. In water samples 1.5–4.0 p.p.m. of fluorine were found. The used mineral supply contained 300–500 p.p.m. of fluorine. The fluorosis in these animals was considered to be caused by a combination of the fluorine of the water and the mineral supplement. Considering the microscopic picture and the low skeletal fluorine level, the lesions in the bull-calves of company B were interpreted as fluorosis being in a process of repair. To this view contributed the fact that the ingested fluorine in these animals was reduced during the fattening period.  相似文献   

8.
Calves (n = 2) born to dams with experimentally induced brucellosis, and calves (n = 4) born to dams with naturally occurring infection were examined by the delayed-type hypersensitivity (DTH) test for possible B. abortus infection. The results were compared with the serum agglutination test, complement fixation test, and Coombs test. Five calves were nursed by their dams for 8-10 weeks after birth. One calf was separated from its dam and fed artificial milk. Three to five months after birth, four calves tested seropositive in the serologic tests. Antibodies were detected in one calf as early as 1 week after birth. The calf fed on artificial milk was seronegative 4-5 weeks after birth. All calves reacted to the DTH test antigen from week 12 until the end of the experiment, even though serologic tests were negative. We conclude that the DTH test is a valuable technique for diagnosing Brucella in calves born to infected dams.  相似文献   

9.
The susceptibility/immune status to tropical theileriosis of calves born of immunized dams was evaluated. Six cows were vaccinated with the Theileria annulata cell culture vaccine in the eighth month of pregnancy. Sera from the immunized dams exhibited very high post-vaccination antibody titres as determined by the indirect fluorescent antibody (IFA) test. The calves born to these dams did not show antibodies against T. annulata at the time of birth (IFA titres of <1:20). The new-born calves were fed colostrum from their mothers and were challenged with T. annulata-infected ground tick supernate at 5–7 days of age. All the calves developed fever (from day 5–6 onwards) and parasitological reactions (from day 8–9 onwards) after challenge. There was a significant decrease in the haemoglobin and packed cell volume of the calves after challenge. All the calves showed signs of acute theileriosis by day 9–10 after challenge and had to be treated with buparvaquone in order to save their lives. The study indicated that detectable levels of anti-theilerial antibodies were not transferred from immune dams to their offspring. All the calves born to immunized dams were fully susceptible to theileriosis and thus themselves needed vaccination.  相似文献   

10.
Summary

Calves (n = 2) born to dams with experimentally induced brucellosis, and calves (n = 4) born to dams with naturally occurring infection were examined by the delayed‐type hypersensitivity (DTH) test for possible B. abortus infection. The results were compared with the serum agglutination test, complement fixation test, and Coombs test. Five calves were nursed by their dams for 8–10 weeks after birth. One calf was separated from its dam and fed artificial milk.

Three to five months after birth, four calves tested seropositive in the serologic tests. Antibodies were detected in one calf as early as 1 week after birth. The calf fed on artificial milk was seronegative 4–5 weeks after birth. All calves reacted to the DTH test antigen from week 12 until the end of the experiment, even though serologic tests were negative. We conclude that the DTH test is a valuable technique for diagnosing Brucella in calves born to infected dams.  相似文献   

11.
An investigation was undertaken to ascertain the possibility of a relationship between calcium, inorganic phosphorus, magnesium, 1,25-dihydroxyvitamin D [1,25(OH)2D], and insulin-like growth factor-1 (IGF-1) concentrations in blood plasma and occurrence of congenital joint laxity and dwarfism (CJLD) in young cattle. Pregnant cows were fed hay (30 cows) or grass silage (122 cows) during winter months (October 15 to calving in March). Blood samples were taken from cows on seven occasions during the experiment and 48 hours after calving, and from calves at birth, and at seven, 14 and 56 days old. Five per cent of calves born (six of 122) to cows fed grass silage and none born to cows fed hay were affected by CJLD. The diet and health status of calves were not significantly (P greater than 0.05) associated with the plasma concentration of 1,25(OH)2D. The plasma calcium concentration declined with age of the calves (P less than 0.05) but was not affected by the occurrence of CJLD. Plasma phosphorus and magnesium concentrations in calves born to cows fed silage were higher (P less than 0.05) than in those born to cows fed hay. At birth and seven days old, plasma phosphorus concentrations were higher (P less than 0.05) in CJLD-affected calves than in healthy calves but the plasma concentration of IGF-1 was not different (P greater than 0.05). It was concluded that the high plasma phosphorus concentrations in CJLD-affected calves and their dams could be related to the aetiology of the CJLD condition in calves.  相似文献   

12.
Potential vertical transmission of wild-type bluetongue virus serotype 8 (BTV-8) in cattle was explored in this experiment. We demonstrated transplacental transmission of wild-type BTV-8 in one calf and oral infection with BTV-8 in another calf. Following the experimental BTV-8 infection of seven out of fifteen multi-parous cows eight months in gestation, each newborn calf was tested prior to colostrum intake for transplacental transmission of BTV by RRT-PCR. If transplacental transmission was not established the calves were fed colostrum from infected dams or colostrum from non-infected dams spiked with BTV-8 containing blood. One calf from an infected dam was born RRT-PCR positive and BTV-specific antibody (Abs) negative, BTV was isolated from its blood. It was born with clinical signs resembling bluetongue and lived for two days. Its post-mortem tissue suspensions were RRT-PCR positive. Of the seven calves fed colostrum from infected dams, none became infected. Of the six calves fed colostrum from non-infected dams spiked with infected blood, one calf became PCR-positive at day 8 post-partum (dpp), seroconverted 27 days later, and remained RRT-PCR and Abs positive for the duration of the experiment (i.e., 70 dpp). This work demonstrates that transplacental transmission in late gestation and oral infection of the neonate with wild-type BTV-8 is possible in cattle under experimental conditions.  相似文献   

13.
Radioimmunoassay (RIA), using the virion glycoprotein antigen, was applied in an attempt to eradicate bovine leukemia virus (BLV) infection from a herd in which virtually all the adult cattle are infected. Considering that most calves born to BLV-infected cows are negative for BLV at birth and remain negative for the first several months of life, the eradication program was based on the identification and isolation of the BLV-free calves born to infected cows. Twenty-five calves raised on colostrum and milk from their infected dams were classified as BLV-free on the basis of negative results in the RIA at 6 to 8 and 9 to 11 months of age. These animals were maintained in either complete (10 calves) or partial (15 calves) isolation from infected cattle and were examined at regular intervals for BLV and BLV antibodies. With the exception of 1 calf in the group raised in partial isolation, the animals have remained free of BLV up to the time of the last evaluation, when they were 32 to 35 months old. At these ages, more than 90% of the nonisolated cattle in the herd are BLV-positive. The data also show that this eradication trial would have failed if, in the initial procedure used to classify the calves as BLV-free, the agar gel immunodiffusion test instead of the RIA had been used. Inasmuch as the 25 calves in this study were fed colostrum and milk from their dams, the fact that only 1 of the calves became infected during the 26 to 29 months of observation provides further evidence that milk-borne transmission of BLV is infrequent and perhaps inconsequential.  相似文献   

14.
Plasma leptin concentrations depend on energy intake and fat stores and are modified by hormones, such as glucocorticoids. We have measured plasma leptin concentrations in pre-term calves (born on day 277 of gestation) during the first week of life, in full-term calves (290 days of gestation), fed similar amounts of nutrients with colostrum or a milk-derived formula, combined with or without dexamethasone treatment (to simulate a high glucocorticoid status), during the first five days of life, and in calves fed with an automatic feeder or by bucket or suckling on dams up to day 28. Leptin concentrations increased (P<0.05) from birth to day 7 in pre-term calves. In full-term calves leptin concentrations were stable from day 1 to day 4 in colostrum-fed animals, but decreased (P<0.05) and were lower (P<0.05) if fed a formula with similar amounts of energy and macronutrients as colostrum. Concentrations increased (P<0.05) from day 1 to day 2 in calves suckling on dams and then remained elevated, but did not change and were lower in calves fed with the automatic feeder or by bucket than in suckling calves. Dexamethasone only slightly elevated leptin concentrations. There was no episodic secretion pattern, and there were no consistent associations of leptin with various metabolites and hormones. In conclusion, plasma leptin in young calves with respect to effects of nutrition (low energy intake) and hormones (glucocorticoids) and in association with metabolic changes behaved differently from what is known in mature cattle.  相似文献   

15.
Our objectives were to examine the effects of added fat in late-gestation cow diets on neonatal response to cold. In Exp. 1, pregnant fall-calving heifers received control (n = 5), safflower seed (n = 5), or whole cottonseed (n = 5) diets. The hay-based, isonitrogenous, and isocaloric diets, fed for 47 d prepartum, contained 1.5, 4.0, and 5.0% fat for control, safflower, and whole cottonseed diets, respectively. At calving, calf BW and vigor score, as well as fat, lactose, and IgG in colostrum were not affected (P > 0.30) by diet. Heifers fed the safflower diet tended to have greater colostral solids (P < 0.10) than heifers fed the control or whole cottonseed diets. At 6.5 h of age, calves were placed in a 5 degrees C cold room for 90 min. Calf vigor, shivering, body temperature, and blood samples were taken every 15 min. During cold stress, calf body temperature decreased 0.7 degrees C (P < 0.03). Across all diets, shivering and serum glucose concentrations increased (P < 0.05), whereas calf vigor and cortisol concentrations decreased (P < 0.02) during cold exposure. In Exp. 2, pregnant spring-calving cows (n = 98) received a control (n = 47) or whole cottonseed (n = 51) supplement. Hay-based diets fed for 68 d prepartum contained 2.0 and 5.0% fat for control and whole cottonseed diets, respectively. Calf BW, vigor, shivering, dystocia score, time to stand, time to nurse, serum glucose concentrations, and serum IgG were not affected (P > 0.50) by diet. Between 30 and 180 min, body temperature of calves from dams fed the whole cottonseed supplement decreased (P < 0.05) more than calves from dams fed the control supplement. Serum glucose concentrations in calves were not affected by diet (P > 0.30). Serum cortisol concentrations tended (P < 0.09) to be greater for calves from dams fed whole cottonseed than control calves. When ambient temperature was < 6 degrees C, calves born to dams fed whole cottonseed had greater (P < 0.05) BW, tended (P < 0.1) to stand earlier, and had greater serum IgG concentrations. We conclude that calves from dams fed high-fat diets containing safflower or whole cottonseed respond similarly to cold stress, but these responses may not be consistent with greater cold resistance. In addition, high-fat dietary supplementation of late-gestation cows may only be beneficial during calving seasons with prolonged cold weather.  相似文献   

16.
Profiles of blood cell counts were evaluated for 15 calves from three different farms. These calves showed petechia in the mucous membranes and in the skin and prolonged secondary bleeding after puncture. The clinical course of the disease could be observed in eleven calves. With exception of one case, the blood cell counts indicated a severe anaemia, leukocytopenia and thrombocytopenia. Out of these 15 calves, six calves survived and the other nine calves died or had to be euthanized due to the severity of the disease. Necropsy of these nine calves revealed petechia in the skin, subcutis, muscles, in inner organs and all serous membranes. Pathohistological examination showed a depletion of the bone marrow and lymphatic tissue in eight calves. These findings confirmed the diagnosis of bovine neonatal pancytopenia (BNP) for eight of these nine calves. Bluetongue virus serotype 8 was tested negatively using PCR. Bovine virus diarrhoea virus (BVDV) was negatively tested using immunofluorescence and cell culture and salmonella species were negatively tested in seven dissected calves. A cluster of toxins was negatively tested in one of the dissected calves. All 15 calves had high antibody titres for BVDV. The BVDV-antibody titres from twelve dams with affected calves were positive in six cases and not detectable in the other six cases. In three of the six dams with not detectable BVDV-antibody titres, calves were fed with colostrum of a further dam with high BVDV-antibody titres. In the further three dams without detectable BVDV-antibody titres, we could not ascertain which colostrum has been fed to the calves. BVDV-specific antigen could not be detected in any of the samples from the calves and dams tested. Using the activity of the gamma-glutamyl-transferase, we assumed a sufficient supply with colostrum for the examined calves.The cause for the occurrence of these BNP cases was due to bone marrow depletion.The reason for the bone marrow depletion remained unclear. However, it was obvious that the BNP described here is highly likely caused by colostrum from cows with positive BVDV-antibody titres.  相似文献   

17.
An experiment was undertaken to evaluate the protective role of boron on the serum profile of buffalo calves fed a high fluoride ration. Twelve male Murrah buffalo (Bubalus bubalis) calves of 6–8 months age, divided into three groups of four calves in each, were fed basal diets and supplemented with sodium fluoride (NaF, 60 ppm) alone or in combination with borax (Na2B4O7.10H2O, 140 ppm) for 90 days. Boron (B) was added in the ration as borax to make @140 ppm boron (elemental B) on DM basis in treatment II. Dietary F caused a significant (p < 0.05) depressing effect on serum Ca and Zn on day 90 which was improved with B supplementation. However, serum Fe and Cu did not show any significant change on F or F+B supplementation. The serum ALP and phosphorus level were increased significantly (p < 0.05) on F feeding but declined significantly (p < 0.05) when B was fed. The findings suggested beneficial effect of boron on serum minerals and ALP in buffalo calves fed high fluoride ration.  相似文献   

18.
A protocol is described to measure the protection of the bovine fetus against an experimental bovine virus diarrhea virus (BVDV) infection after vaccination. Two inactivated experimental vaccines were applied twice with a 3 week interval. A mixture of three different Dutch field strains was used as challenge on mainly the 82nd day of gestation to vaccinated and unvaccinated control animals. The challenge was applied 5 months after completion of the two-fold vaccinations. All calves born from unvaccinated control animals were persistently infected. The calves born from dams vaccinated with the two different inactivated BVDV vaccines were persistently infected in 78 and 60%, respectively.  相似文献   

19.
Beef calves in a 48-cow herd were studied during one calving season from birth to ten days of age to determine the presence or absence of potentially enteropathogenic bacteria, viruses, and/or chlamydia in both normal and diarrheic calves. Calves were born and raised outside in large pens unless the ambient temperature was below minus 10 degrees F when calving was done inside. Fecal swabs, fecal aliquots, and nasal swabs were taken from each calf at 32, 128 plus or minus 3, and 248 plus or minus 3 hours of age and as soon after the onset of diarrhea as possible. Diarrhea was defined as that condition in which the feces contained less than 10% dry matter. Enteropathogenic Escherichia coli in feces were identified using the ligated gut loop procedure in calves and by feeding broth cultures to colostrum fed lambs seven to 16 hours old. Potentially enteropathogenic viruses were detected using a variety of methods which included tissue culture, fluorescent antibody, hemadsorption, and electron microscope techniques. Of the 40 calves studied, 32 (80%) developed diarrhea before ten days of age. Twenty-two strains of Escherichia coli which caused dilation of calf ligated intestinal loops were isolated from 11 scouring calves and from one normal calf. Nine out of ten strains of Escherichia coli which dilated ligated loops also caused diarrhea when fed to colostrum-fed lambs seven to 16 hours old. Using antibody technique a Reo-like virus was detected in the feces of 15 calves before, during, and after the onset of diarrhea. Four calves excreted both loop dilating strains of E. coli and Reo-like virus in the feces before ten days of age; in all cases the loop dilating E. coli were isolated from the feces prior to the demonstration of Reo-like virus. A Corona-like virus was also demonstrated in three of the 15 calves infected with Reo-like virus and a noncytopathogenic strain of bovine virus diarrhea virus was isolated from two of the 15 calves infected with Reo-like virus. A loop dilating strain of Citrobacter was isolated from one diarrheic calf. There was no consistent pattern of onset or duration of diarrhea in calves which excreted different infectious agents. Salmonella species, infectious bovine rhinotracheitis virus, parvovirus, adenoviruses, parainfluenza-3 virus, and Chlamydia species could not be demonstrated in any of the calves or their dams. No potentially enteropathogenic agents could be demonstrated in 11 of the 32 calves which scoured. These findings emphasize the complexity of the infectious aspect of the neonatal diarrhea syndrome and illustrate the difficulty in making an etiological diagnosis in field outbreaks of the calf scours complex.  相似文献   

20.
Transfer of immunoglobulins and survival of newborn calves   总被引：1，自引：0，他引：1  
The survival of 405 newborn calves in a large Central Florida dairy was monitored for a period of 20 weeks. Post-colostral serum samples were obtained from 234 newborn calves 2 to 7 days postpartum and assayed for total serum protein concentration using a refractometer. In the dams, the concentration of colostral immunoglobulins (Ig) at the first postpartum milking was determined by a colostrometer. Season of calving, sex, and breed of the newborn calves were recorded. The likelihood a calf would have satisfactory serum protein (greater than or equal to 5.5 g/dl) given its breed, season of calving, dam's colostral Ig, and dam's calving body condition score were determined using logistic regression analysis. Factors affecting the survival of these calves, up to 20 weeks of age, were studied using the Cox's proportional hazard model. Newborn calves' serum proteins ranged from 3.0 to 8.3 g/dl with a mean of 5.1 g/dl. Calves born to dams with satisfactory colostral Ig (greater than or equal to 50 mg/ml) were unlikely to have satisfactory serum proteins (odds ratio = 0.4) after adjustment for season of calving, parity, breed and dam's body condition score. Calves born from October to January were 3 times more likely to have satisfactory serum proteins compared to calves born during the period of February to July. However, there was no difference in serum proteins between calves born in August and September compared to the ones born in February to July. The survival rate of calves born to dams with satisfactory levels of colostral Ig was poor compared to ones born to dams with low colostral Ig.  相似文献   

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