Comparative study of selected blood biochemical components in milk or milk-replacer fed calves during the second week of life

The experiment was carried out on 13 male Polish Black and White dairy calves of 75% share of the Holstein-Friesian (HF) breed during the second week of life. The animals were divided into two groups. One group (n=7) was fed mother's milk and the second (n=6) milk replacer. The dynamics of changes in concentration of selected blood biochemical components connected with nitrogen metabolism (plasma total protein, albumin, urea, endogenous creatinine) and with mineral metabolism (sodium, chloride, calcium, magnesium, zinc, copper and plasma osmotic pressure) were analyzed in both groups. The results show that the type of ingested food influences the concentration of indicators reflecting nitrogen metabolism. Changes of these parameters in calves fed milk replacer are possibly connected with advantageous catabolic changes. Stable concentrations of main extracellular fluid electrolytes and blood plasma osmotic pressure were found in both groups of calves. Constant blood plasma calcium, magnesium, zinc and copper concentrations observed during this study might also indicate the relative maturity of mechanisms maintaining water and electrolyte balance. Nevertheless, it seemsjustifiable to monitor the copper concentrations in plasma of young calves.     

Behaviour of calves at introduction to nurse cows after the colostrum period

In traditional housing systems for dairy herds, calves are very often placed in single boxes and fed milk from a bucket, which may lead to abnormal behaviour. In organic herds, for whom the aim is optimal animal welfare, there is interest in using suckling systems, where the calves have the opportunity to perform natural social behaviour. The success of introducing a calf to a nurse cow is expected to depend on the calf's suckling experience, as well as the introduction procedure. A two-factorial experiment was carried out with the objective to investigate how calves are best introduced to the nurse cow during (the colostrum period (defined as the first 3 days postpartum). The calf was either with its own mother or fed colostrum from a teat-bucket. The length of the introduction period, where the calf was alone with the nurse cow before being introduced to a larger group of cows and calves, was either 1 or 2 days. The experiment showed that calves who had suckled colostrum from their own mother, suckled the nurse cow more and for longer periods than the teat-bucket fed calves (P=0.0007 on day 1 and P=0.012 on day 2). Mothered calves licked and rubbed their nurse more (16.7 times versus 7.0 times; S.E.M.+/-2.3; P<0.05) and these calves cross-suckled less than teat-bucket fed calves (19.9min versus 54.5min; S.E.M.+/-14.9; P=0.03).     

Concentration of lactoferrin and transferrin throughout lactation in cow's colostrum and milk

The evolution of the concentration of lactoferrin and transferrin was studied in cow's colostrum and milk throughout lactation. The highest concentrations of both proteins were found in the first milking (0.83 mg/ml for lactoferrin and 1.07 mg/ml for transferrin), decreasing sharply during the first days of lactation (colostral period). Thereafter, the concentrations of these proteins decreased slowly, reaching their definitive values during the third week post-partum (0.09 mg/ml for lactoferrin and 0.02 mg/ml for transferrin). The ratio transferrin/albumin in colostrum (first milking), mature milk, milk from mastitic cows and serum was determined, and found to be four times greater in colostrum than in mature or mastitic milk, suggesting a specific transport of transferrin from blood to milk.     

Serum immunoglobulin type G concentrations in calves produced by IVF and delivered by elective cesarean section

Colostrum ingestion by neonatal calves is widely recognized to provide passive transfer of immunity. In this study immunoglobulin absorption from colostrum was evaluated in 54 IVF-produced calves. The IVF calves were delivered by Cesarean section on Days 275 to 277 of gestation, 24 h after the dams had been administered 30 mg dexamethasone. The calves suckled bottles or were force-fed 6 L of colostrum in the first 12 h of life. Colostrum was obtained from the first post-calving milking of recipient dams or from frozen storage reserves if dam secretion was not adequate. Immunoglobulin type G (IgG) content of both sources of colostrum was determined. Serum samples from the calves were collected at 0, 12 and 24 h of age and analyzed for IgG. Twenty dairy calves born vaginally served as the controls and were subjected to the same colostrum management protocol except that the colostrum was obtained only from frozen post-calving milk of dairy cows from the same farm. The control calves were also subjected to the same sampling protocol. The IVF group of calves ingested more IgG (P < 0.0001) and absorbed more IgG by 24 h of age (P < 0.0001) than their control group counterparts. Absorption of IgG was analyzed by comparing the g/kg body weight of IgG with serum IgG values at corresponding times after birth. Colostrum absorption efficiency was the same for both IVF and control groups of calves at 12 and 24 h of age. There was a maximum IgG dose above which additional increases in serum IgG were not realized. The slightly premature, Cesarean delivered IVF calves absorbed IgG from colostrum similarly to control calves delivered vaginally.     

Effects of lactoferrin feeding on growth, feed intake and health of calves

Lactoferrin (LF) exhibits a broad spectrum of anti-microbial properties and may have regulatory functions in the immune system. In the present study, 40 calves (20 males, 20 females) were used to examine the effects of supplemental bovine LF added to colostrum and milk replacer (at 0.16%) on health, weight development and feed intake during a 70-day experimental period. The calves were allocated to a treatment group (n = 20) and a control group (n = 20); the groups were balanced in terms of sex, live weight and date of birth. Body weight and feed intake were measured at regular intervals. Blood and colostrum samples were collected to determine the content of IgG. In addition, colostrum and milk replacer samples were analysed for their LF concentrations. Significantly higher IgG values were observed in the LF treated than in the control group during the entire feeding experiment from week 2 to week 6. Calves receiving LF had less days of disease with less serious cases of diarrhoea than the control group. Body weight and feed intake were not significantly different between the treatments; in male calves LF-treated animals tended towards higher weight gains. This study indicates that LF is advantageous for health and may therefore be a beneficial supplement in the diets for neonatal calves.     

The effects of feeding high or low milk levels in early life on growth performance,fecal microbial count and metabolic and inflammatory status of Holstein female calves

Gut microbial colonization and immune response may be affected by milk feeding method. The objective of this study was to determine the effects of feeding high or low volumes of milk on fecal bacterial count, inflammatory response, blood metabolites and growth performance of Holstein female calves. Colostrum-fed calves (n = 48) were randomly assigned to either high milk (HM; n = 24) or low milk (LM; n = 24) feeding groups. Low milk-fed calves were fed pasteurized whole milk at 10% of BW until weaning. In HM group, milk was offered to calves at 20% of BW for the first 3 weeks of life. Then, milk allowance was decreased gradually to reach 10% of BW on day 26 and remained constant until weaning on day 51. Calves were allowed free access to water and starter throughout the experiment. Body weight was measured weekly, and blood samples were taken on days 14, 28 and 57. Fecal samples were collected on days 7, 14 and 21 of age for the measurement of selected microbial species. By design, HM calves consumed more nutrients from milk during the first 3 weeks and they were heavier than LM calves on days 21, 56 and 98. High milk-fed calves had greater serum glucose and triglyceride levels on day 14 with no significant difference between groups on days 28 and 57. Blood urea nitrogen was higher in LM calves on day 14, but it was lower in HM calves on day 28. Calves in LM group had significantly greater blood tumor necrosis factor-α (TNF-α) than HM calves throughout the experiment. Serum amyloid A (SAA) concentration was higher in LM calves on day 14. However, HM calves showed higher levels of SAA at the time of weaning. Feeding high volumes of milk resulted in lower serum cortisol levels on days 14 and 28 but not at the time of weaning in HM calves compared to LM counterparts. Lactobacillus count was higher in feces sample of HM calves. Conversely, the numbers of Escherichia coli was greater in the feces of LM calves. Calves in HM group showed fewer days with fever and tended to have fewer days treated compared to LM group. In conclusion, feeding higher amounts of milk during the first 3 weeks of life improved gut microbiota, inflammation and health status and growth performance of Holstein dairy calves.     

Leptin in bovine colostrum and milk.

We studied leptin content in bovine colostrum, milk and plasma during the first month of lactation, and investigated relationships between selected milk components and milk leptin in five multiparous dairy cows. Colostrum/milk yield and composition were measured on days 0, 10, 20, and 30 of lactation. Leptin was assayed using a multi-species leptin RIA kit. Leptin concentration was 56 % lower in mature milk (day 10) than colostrum (13.90 vs. 6.14 microg/l; p < 0.001), but remained steady over the twenty days afterwards. Daily secretion of leptin into mature milk was 28 % lower than into colostrum (173.2 microg/d vs. 220.0 microg/d; p = 0.09) notwithstanding an 80 % increase in production. Colostrum and milk leptin levels correlated with fat (0.90; p < 0.001) and choline phospholipid (0.76; p < 0.05). Plasma and milk leptin decreased during the first month, but remained higher in milk, and highest in colostrum. Thus, leptin is present in large quantities in colostrum, less so and more variably in untreated milk, and is likely to be decreased in skimmed milk. These findings have implications for the use of untreated milk and colostrum-based (functional) food products.     

Effects of lactoferrin feeding on growth,feed intake and health of calves

Abstract

Lactoferrin (LF) exhibits a broad spectrum of anti-microbial properties and may have regulatory functions in the immune system. In the present study, 40 calves (20 males, 20 females) were used to examine the effects of supplemental bovine LF added to colostrum and milk replacer (at 0.16%) on health, weight development and feed intake during a 70-day experimental period. The calves were allocated to a treatment group (n = 20) and a control group (n = 20); the groups were balanced in terms of sex, live weight and date of birth. Body weight and feed intake were measured at regular intervals. Blood and colostrum samples were collected to determine the content of IgG. In addition, colostrum and milk replacer samples were analysed for their LF concentrations. Significantly higher IgG values were observed in the LF treated than in the control group during the entire feeding experiment from week 2 to week 6. Calves receiving LF had less days of disease with less serious cases of diarrhoea than the control group. Body weight and feed intake were not significantly different between the treatments; in male calves LF-treated animals tended towards higher weight gains. This study indicates that LF is advantageous for health and may therefore be a beneficial supplement in the diets for neonatal calves.     

Transfer of passive immunity in dairy calves: the effectiveness of providing a supplementary colostrum meal in addition to nursing from the dam

Failed transfer of passive immunity (FTPI) in dairy calves – which is often due to the low amount of colostrum provided within a few hours after birth – remains a crucial issue. Enabling dairy calves to nurse colostrum from their dams could be useful in increasing intake and thus avoiding FTPI, but further potential effects on the health and welfare of both calves and dams should also be considered. In this study, 107 calf-dam pairs from two Italian dairy farms were alternately assigned to one of the following colostrum provision methods (CPMs): ‘hand-fed method’ (HFM) – the calf was separated from the dam immediately after birth and colostrum was provided by nipple-bottle (n = 50); ‘nursing method’ (NM) – the calf nursed colostrum from the dam for the first 12 h of life without farmer assistance (n = 30); and ‘mixed method’ (MM) – the nursing calf received a supplementary colostrum meal by nipple-bottle (n = 27). Serum of calves (1 to 5 days of age) and samples of their first colostrum meal were analysed by electrophoresis to assess immunoglobulin (Ig) concentration. Additionally, behavioural indicators of separation distress (calf and dam vocalisations; calf refusal of the first meal after separation; undesirable dam behaviour at milking) in the following 24 h were recorded as binary variables (Yes/No), and the health status of calves (disease occurrence and mortality) and dams (postpartum disorders and mastitis occurrence) were monitored for the first 3 months of life and 7 days after parturition, respectively. The lowest FTPI occurrence (calf serum Ig concentration <10.0 g/l) was found in the MM (11.1%) and the HFM (22.0%) compared with the NM (60.0%) (P<0.05), and the highest percentage of calves with optimal transfer of passive immunity (serum Ig concentration ≥16.0 g/l) was observed in the MM (55.6%). The lowest calf–dam separation distress was observed in the HFM (P<0.05). The highest calf disease occurrence was recorded in the HFM (64.0%) and the lowest in the NM (33.3%), with an intermediate value for the MM (44.4%) (P<0.05). No effect of the CPM was observed on dam health or calf mortality (P>0.05). The results of this study indicated that providing calves with a supplementary colostrum meal in addition to nursing from the dam (MM) is truly effective in maximizing passive immunity transfer. Anyway, specific strategies should be studied to minimise calf-dam separation distress.     

Fluorimetric study of the selenium course in the dam-calf relationship

This study was conducted in a southeast region of Romania, known to be selenium (Se) deficient. The fluorimetric method for the determination of Se in biological samples was used in a study on the serum Se content in time in a group of 10 cows with a high milk yield and in their calves. The same cows were sampled antepartum (late pregnancy) and postpartum (1, 7, 21, 30, and 60 d), and the calves were sampled on d 1 of life and 7, 21, 30, and 60 d postcalving. Colostrum and milk samples were also collected and analyzed at the same times. Throughout the study, the serum Se content in both the cows and the calves was below the reference values (0.040–0.100 μg/mL), except the control conducted 7 d postpartum, for which it was 0.044±0.017 and 0.023±0.007 μg/mL in cows and calves, respectively. The most significant drops were recorded 21 (p<0.01) and 60 d postpartum (p<0.05). The colostrum Se was higher (0.036±0.022 μg/mL), decreasing progressively throughout the study to the normal low limit (0.005 μg/mL). The milk Se concentration was lower by approx 78% than the colostrum one on d 1 postcalving. These data demonstrate the course of hyposelenosis both in the cows and their calves. The maternal body proved to “mobilize,” even in case of deficiency, important Se amounts in the colostrum, during the first days in particular.     

Factors associated with passive immunity transfer in dairy calves: combined effect of delivery time,amount and quality of the first colostrum meal

Despite the well-known importance of an adequate colostral immunoglobulin (Ig) transfer to calf health and survival, failed transfer of passive immunity (FTPI) remains a widespread problem in dairy farming. The aim of this study was to investigate the management factors associated with FTPI in newborn calves, evaluating particularly the combined effect of delivery time, amount and quality of the first colostrum meal. The study was conducted from March to August 2014 on 21 Italian dairy farms. Farmers were asked as first to answer a farm-level questionnaire on calf management. Blood sampling was then performed on overall 244 calves (1 to 5 days of age) born from Holstein cows, and a sample of the first colostrum meal of each calf was collected. Individual information on calves and the respective colostrum management were recorded. Serum and colostrum Ig concentrations were assessed by electrophoresis. A mixed effects multivariable logistic regression model was used to investigate the association of the variables obtained from both the management questionnaire and the individual calf data with FTPI (calf serum Ig concentration <10.0 g/l). A cumulative colostrum management score (CMS) that considered delivery time, amount and quality of the first colostrum meal was generated for 236 calves, with higher values indicating better colostrum management. Overall, 41.0% of the calves were found having FTPI, and within-farm percentage of FTPI was over 20.0% in 71.4% of the farms. The risk of having FTPI was higher both for Holstein purebred calves compared with Holstein-beef crossbreds and for females compared with males. Moreover, it increased by 13% with every hour of delay of the first colostrum meal provision since birth, whereas it decreased by 59% and 3%, respectively, with every additional liter of colostrum given and every additional gram of Ig per liter contained in the colostrum fed. Calf serum Ig concentration varied significantly according to the CMS, increasing by 1.53 g/l with every additional CMS point. In order to completely avoid FTPI, calves should receive at least 2.5 l of high-quality colostrum (Ig concentration >87.6 g/l) within 1.0 h from birth. Considerable improvements are still needed about colostrum management for newborn calves in dairy farms. The results of this study will help in developing farm-specific programs for reducing the occurrence of FTPI.     

Gel electrophoretic analysis of proteins in human milk and colostrum

Protein patterns of skim milk and fat globule phases were relatively unchanging throughout 9 months lactation, the only notable differences being a rise in lysozyme and a decline up to 6 months with increase thereafter in lactoferrin. Profound changes in protein patterns of the breast secretion were observed during the first week postpartum. True colostrum, in which peptides of sIgA dominate the protein patterns, exists for at most the 2 initial days of secretion. Proteins of mature milk are not coordinated to appear in the colostral secretion simultaneously. A band corresponding to alpha-lactalbumin is present from the initial secretion; that for beta-casein emerges approximately 2 days layer.     

Influence of weaning regimen on intake,growth characteristics and plasma blood metabolites in male buffalo calves

Experiment was conducted to evaluate the effect of weaning age on growth performance, feed intake, feed efficiency (FE) and blood metabolites in Nili-Ravi male buffalo (Bubalus bubalis) calves. Twenty-four male buffalo calves were assigned to one of the three treatment groups: continuous milk feeding (CMF), limited milk feeding (LMF) and early weaning (EW), and weaned off milk at 12, 10 and 8 weeks of age, respectively. For the first 3 days after birth, calves in all three treatments were fed colostrum, and were then moved to individual milk feeding at 10% of BW for the next 6 weeks. Thereafter, the provision of milk to the CMF group was gradually tapered to zero through week 12, using week 6 intakes as a base. The LMF calves were fed milk at 7.5%, 5.0%, 3.5%, and 1.5% of BW during weeks 7 to 10, respectively. Lastly, calves in the EW group were fed milk at 5.0% and 2.5% of BW at weeks 7 and 8, respectively. Calf starter (CS) feed was also provided ad libitum from weeks 2 to 12 and individual intakes were recorded on a daily basis. Blood samples were taken from weeks 6 to 12, on a weekly basis; whereas, the BW, heart girth, withers height and hip width were measured at the start of experiment and later on a weekly basis. Weight gain, average daily gain, and body measurements were the same across all three groups. Milk intake was lower (P < 0.05), whereas CS intake was greater (P < 0.05) in the EW calves compared with the other treatment groups. Dry matter intake was greater (P < 0.05) in the EW and LMF calves compared with the CMF calves. The FE was greater (P < 0.05) in the CMF calves compared with the LMF and EW treatment groups. Blood glucose concentration was similar among the treatments; however, blood urea nitrogen was greater (P < 0.05) in the EW calves compared with the CMF and LMF groups. Plasma concentration of non-esterified fatty acids was higher (P < 0.05) in the EW calves compared with the CMF calves. In light of these results, it is evident that buffalo calves can be successfully weaned as early as 8 weeks of age without negatively affecting their growth performance.     

Impact of longevity on greenhouse gas emissions and profitability of individual dairy cows analysed with different system boundaries

Dairy production systems are often criticized as being major emitters of greenhouse gases (GHG). In this context, the extension of the length of the productive life of dairy cows is gaining interest as a potential GHG mitigation option. In the present study, we investigated cow and system GHG emission intensity and profitability based on data from 30 dairy cows of different productive lifetime fed either no or limited amounts of concentrate. Detailed information concerning productivity, feeding and individual enteric methane emissions of the individuals was available from a controlled experiment and herd book databases. A simplified GHG balance was calculated for each animal based on the milk produced at the time of the experiment and for their entire lifetime milk production. For the lifetime production, we also included the emissions arising from potential beef produced by fattening the offspring of the dairy cows. This accounted for the effect that changes in the length of productive life will affect the replacement rate and thus the number of calves that can be used for beef production. Profitability was assessed by calculating revenues and full economic costs for the cows in the data set. Both emission intensity and profitability were most favourable in cows with long productive life, whereas cows that had not finished their first lactation performed particularly unfavourably with regard to their emissions per unit of product and rearing costs were mostly not repaid. Including the potential beef production, GHG emissions in relation to total production of animal protein also decreased with age, but the overall variability was greater, as the individual cow history (lifetime milk yield, twin births, stillbirths, etc.) added further sources of variation. The present results show that increasing the length of productive life of dairy cows is a viable way to reduce the climate impact and to improve profitability of dairy production.     

Effects of Short-term Supplementation of Clinoptilolite in Colostrum and Milk on the Concentration of Some Serum Minerals in Neonatal Dairy Calves

In recent years, the use of both natural and synthetic zeolites in animal nutrition has increased mainly to improve their performance, health, and to protect against mycotoxin intoxication. Thirty calves were used in the present study for the determination of some physiologic effects of clinoptilolite supplementation. The animals were divided equally into three groups (control, test 1, and test 2). The three groups of calves were homogeneous for parity of dams, sex, and month of birth. For group test 1, clinoptilolite in the concentration of 2% of each colostrum meal was added for 48 h, and for group test 2, clinoptilolite in the concentration of 2% was added to each colostrum and milk meal for 14 days. Blood samples were taken from all calves 12 h after birth and at the end of the first, second, third, forth, fifth, and sixth weeks of life. Calcium (Ca), phosphorus (P), magnesium (Mg), iron (Fe), sodium (Na), and potassium (K) were determined in the serum. For statistical analysis of data, a repeated measures approach using analysis of variance (ANOVA) with mixed linear models was used. Clinoptilolite supplementation had significant effect on the concentrations of calcium, phosphorus, sodium, and iron. The concentrations of Fe significantly higher in test group 2 than other trial groups (p < 0.05). Calcium concentrations were significantly higher in serum of clinoptilolite-treated than control calves (p < 0.05). The concentrations of phosphorus were significantly lower in test groups than control group (p < 0.05). Sodium concentrations were significantly higher in clinoptilolite-supplemented groups than control calves (p < 0.05). Potassium and magnesium concentrations were not affected by clinoptilolite supplementation. Clinoptilolite supplementation could promote iron levels in serum and better hemopoiesis and prevent pathologic or physiologic drop of red blood cell (RBC) parameters in supplemented calves during a first few weeks of life. According to higher need and utilization of Ca in growing animals, clinoptilolite supplementation could increase available Ca. Based on the results of the present study and the importance of dietary phosphorus in many physiologic processes, the level of phosphorus in diet of neonatal dairy calves must be considered and adapted when clinoptilolite was supplemented. With an adequate supply of good quality drinking water, cattle can tolerate large quantities of dietary sodium chloride. Thus, it seems that significant increase in serum Na concentration during short-term supplementation of clinoptilolite in neonatal calves could be well tolerated without any adverse effects.     

Levels of cytokines (IL-1beta, IL-2, IL-6, IL-8, TNF-alpha) and trace elements (Zn, Cu) in breast milk from mothers of preterm and term infants

It has been well documented that human milk contains several immunomodulator components which are important during infant period when the newborn's immune system is still under development. In this study, we aim at examining levels of cytokines, zinc (Zn), and copper (Cu) in milk from mothers of premature and mature infants, and comparing changes during lactation periods consequently. Milk was collected from total of 40 mothers (group M: mothers of mature infants, n = 20; group PM: mothers of premature infants, n = 20) from four lactation stages: colostrum (0-7 days), transitional (7-14 days), mature milk (21 days), and mature milk (2nd month). Levels of cytokines (interleukin [IL]-lbeta, IL-2, IL-6, IL-8, tumor necrosis factor-alpha [TNF-alpha]) were determined by chemiluminesence method, whereas atomic absorption spectrophotometer was used for the determination of Zn and Cu levels. Cytokine levels were determined to be high in colostrum and transient milk from mothers of full-term infants, whereas their levels were reduced drastically in the 21st day and the 2nd month milk (P < .01, P < .001). Similar trends were observed in milk from mothers of premature infants, but cytokine levels were significantly lower in colostrum compared to colostrum from mothers of mature infants (P < .01). The differences in cytokine levels were continuous in transient milk (P < .05) and mature milk (21 days) (P < .05), whereas there was no statistically significant differences between milk from both groups of mothers in the 2nd month (P > .05). Zn levels in milk from mothers of premature infants were significantly lower compared to the ones from mothers of mature infants (P < .01) and these differences continued through the 2nd month. Although Cu levels were lower in milk from mothers of premature infants, there was no statistically significant difference except colostrum (P > .05). Our results clearly demonstrate that the level of immunomodulating agents such as cytokines and trace elements in milk from mothers of premature infants is less than the level of the same agents in milk from mothers of full-term infants. Although there are commercially available products for infant feeding, human milk is still the best natural nutrient for newborns. Therefore, when premature infants are breastfed, necessary precautions such as supplemantary diets must be considered for possible infections and risks related with immune system deficiency.     

The effect of calf jacket usage on performance,behaviour and physiological responses of group-housed dairy calves

Poor performance and ill-health of calves in the pre-wean period can affect future productivity. Increasing numbers of producers are opting to use calf jackets as a means of mitigating the potential negative effects of low ambient temperatures, wind speed and precipitation on growth and health. This study aimed to use a range of noninvasive monitoring technologies to investigate the effects of using calf jackets in the first 3 weeks of life on calf performance and behavioural and physiological parameters. Ninety Holstein-Friesian calves were allocated to one of the two treatments: (i) Jacketed until 21 days of age and (J; n = 44) ii. Nonjacketed (NJ; n = 46). Calves were group housed and fed milk replacer (MR) and concentrate solid feed via automatic feeders. Calves were weaned at day 56, and the experiment was completed at day 63. Health assessments were conducted on a daily basis throughout the experiment using predefined faecal and respiratory scoring protocols. A range of novel, noninvasive monitoring technologies were used to examine the activity, heart rate and thermal profiles of calves on an individual basis throughout the experimental period. There were no differences in calf live weight (LWT), average daily gain (ADG) or feed conversion efficiency (FCE) in J and NJ calves between days 5 to 20. However, NJ calves consumed more MR and had more unrewarded visits to the milk feeder than J calves during this period. Although calf LWT was comparable across treatments in the week following jacket removal (days 21 to 28), both ADG and FCE tended to be greater in NJ calves. There were no treatment differences in calf LWT at the end of the study (d63). When measured over a period of 24 h and at a mean ambient temperature of 7.7°C, skin surface temperature was 6.37°C higher in J calves. Core body temperature was higher in J calves between days 5 to 20; however, there were no differences in IR eye or IR rectal temperature. No differences in lying behaviour occurred, with calves spending 18 and 17 h/day lying between days 5 to 20 and days 21 to 28, respectively. Under the climatic and management conditions described, no significant benefits to calf performance were found as a result of the provision of calf jackets to group-housed calves in the first 3 weeks of life. The higher frequency of unrewarded visits to the milk feeder in NJ calves during the first 3 weeks of life could be suggestive of a lack of satiety in these calves.     

Synthesis and evolution of concentration of beta-lactoglobulin and alpha-lactalbumin from cow and sheep colostrum and milk throughout early lactation

Synthesis of beta-lactoglobulin and alpha-lactalbumin by explants of ovine mammary gland and evolution of concentration of these proteins in cow and sheep colostrum and milk throughout early lactation have been studied. The evolution of both proteins was similar in cow and sheep species. The highest concentration was found in the first milking (19 and 2 mg/ml for beta-lactoglobulin and alpha-lactalbumin, respectively). Then, levels of beta-lactoglobulin decreased sharply and those of alpha-lactalbumin slowly during the first days of lactation, reaching stable values during the second week postpartum (4 and 1.5 mg/ml). The concentration ratio beta-lactoglobulin/alpha-lactalbumin was four times greater in colostrum than in mature milk. On the other hand, synthesis of these proteins represented about 25-30% of the synthesized total soluble proteins. The synthesis ratio beta-lactoglobulin/alpha-lactalbumin in explants obtained at 12 and 30 hours postpartum was found to be 3.5 and 1.7. These results indicate that the synthesis and secretion of beta-lactoglobulin are comparatively greater than those of alpha-lactalbumin during colostral period, suggesting that beta-lactoglobulin could have some specific function during this period.     

The effect of irregular feeding times on the behaviour and growth of dairy calves

The objective of this study was to examine the effects of predictable vs. unpredictable management routines on the behaviour, production and health of dairy calves. Three different feeding schedules for milk-fed dairy calves were compared. All calves received milk twice a day, and had free access to concentrate, hay and water. Three groups of 12 calves (divided on two trials) were exposed to one of the following treatments from the age of 5 days to 9 weeks: group C (control) received milk at the same time every day, at 0700 and 1400. Group OD (occasional deviation) received the milk at the same time every day except on treatment days, one in week 5 and one in week 8, where they were fed 3 h later. Group IR (irregular schedule) received milk at irregular times throughout the experimental period. The first daily feeding took place between 0600 and 1300 and the second one between 1300 and 2100. When the calves were 5 and 8 weeks old, the behaviour of eight calves from each group was videorecorded for two days (48 h). The following behaviour was recorded: frequency and duration of lying bouts and frequency of comfort behaviour (defined as licking or scratching own body), eating, drinking, other oral behaviour and extending the head through the feeding barrier (HTB). The milk and concentrate consumption of the calves was measured and the calves were weighed weekly. Diseases were recorded.The results showed that at the age of 5 weeks, the calves in group IR differed from the control group C by performing more eating behaviour both on the control day (27.5 vs. 15.5; p<0.05) and the treatment day (28.8 vs. 18.3; p<0.05). At the age of 8 weeks, no differences were found in the behaviour between groups IR and C. When the OD calves were 5 weeks old, they responded to the delayed feeding by increasing drinking behaviour (14.5 vs. 9.0; p<0.05). When they were 8 weeks old, they showed increased frequency of comfort (195 vs. 122; p<.05), eating (37.5 vs. 27.9; p<0.05) and HTB behaviour (19.8 vs. 7.4; p<0.001) on the treatment day compared to the control day. The IR group did not respond to the same treatment except for a slight increase in drinking behaviour (9.6 vs. 6.5; p<0.05) at the age of 8 weeks. No differences were observed in the frequency or length of lying bouts, nor health or production parameters between the three groups.It is concluded that a predictable feeding schedule may not be very important for milk-fed dairy calves. However, when the calves are customised to predictable feeding times, occasional deviations from that schedule may cause frustration when their expectations are not fulfilled.     

Renal regulation of potassium homeostasis in calves in the first week of life including the role of atrial natriuretic peptide

The experiment was carried out on 10 clinically healthy Polish-Friesian var. Black-and-White cow calves, during the first seven days of postnatal life. The results indicate that renal removal of potassium depends primarily on the quantity reabsorbed in the tubules, whereas clearance of the electrolyte, due to stable levels in the blood plasma, depends on the amount excreted in the urine. With stable tubular reabsorption of potassium, a relatively unchanging amount of excreted potassium was observed in the urine. However, reduced tubular reabsorption caused a significant increase in excretion and clearance of the electrolyte. Changes in the amount of filtered potassium play a minor role in the regulation of excretion. Small changes in the blood plasma potassium concentration observed primarily resulted from changes in glomerular filtration rate and tubular reabsorption, since the concentration of electrolyte in the blood after birth remained within the physiological range. The results ofthis study suggest that neonate calf kidneys are sufficiently prepared to regulate kalemia. Atrial natriuretic peptide is not directly involved in the regulation of tubular reabsorption of potassium in calves in the first week of life, although it is highly likely that the peptide is involved in the excretion of potassium in the urine in calves during the first seven days of life.