Figure 1. Mean birth , weeks 1 to 6, and final 42-day body weights (kg) of calves on the immunoglobulin experiment for all treatment groups.
S.M. Whitaker, S.L. Jeffrey, L.B. Willett, D.C. Borger,
R.L. Neiswander, F.L. Schanbacher, and W.P. Weiss
Department of Animal Sciences
If calves do not get sufficient colostrum containing immunoglobulins soon after birth, they have compromised ability to resist diseases. The adrenal hormone cortisol may be able to delay "gut closure" and improve immunoglobulin absorption in calves that do not get colostrum for several hours after birth. Calves were allotted to three treatment groups of 1) cortisol and immunoglobulin, 2) cortisol and no immunoglobulin, and 3) sham and immunoglobulin. Treatment groups were subdivided into feeding times of 2, 7, and 12 hours postpartum. The results of this study confirmed that the time of first colostrum feeding significantly influences immunoglobulin absorption. The calves that received cortisol had higher final serum immunoglobulin concentrations than those that did not. It was very interesting to note that "gut closure" may not occur as rapidly as was once postulated.
The bovine placenta is referred to as a "closed system". This means that very few antibodies can cross the placental barrier; thus, the neonate is born essentially devoid of immunoglobulins in the blood. The newborn is left with a compromised ability to fight pathogens. To acquire initial immunity, the neonate must nurse and absorb the essential immunoglobulins provided in colostrum, or first milk.
The time relative to birth that the calf receives its first feeding of colostrum is critical due to "gut closure". This process occurs soon after birth and is characterized by rapid loss of the ability to effectively absorb immunoglobulins. Studies have shown that the first feeding must take place within the first 12 hours after birth, or the amount of immunoglobulins absorbed was significantly reduced (Stott et al., 1979a). Simultaneously, the concentration of immunoglobulins in the colostrum was decreased (Stott et al., 1979c).
The role of the adrenal corticoid hormone, cortisol, in immunoglobulin absorption by neonates is unclear. Studies with rat pups have shown that the presence of cortisol greatly reduced the pups' ability to absorb the passively transferred immunoglobulins (Johnson and Oxender, 1979). For many years, the same was true of other mammals. However, more recent studies with lambs (Hough et al., 1990) and calves (Johnson and Stewart, 1986) suggested that the ruminant intestinal tract was very different from other mammals. These studies concluded that the presence of cortisol may actually increase immunoglobulin absorption (Johnson and Oxender, 1979). If true, administration of cortisol may help absorption of immunoglobulins from the colostrum and perhaps be effective when feeding colostrum is delayed past the time of optimal absorption. The purpose of this research was to study the effects of cortisol and the time postpartum of the first colostrum feeding on immunoglobulin absorption in newborn calves.
Twenty-seven Holstein calves were assigned randomly to three treatment groups: 1) bovine Immunoglobulin G (IgG) and cortisol; 2) no IgG and cortisol; and 3) bovine IgG and no cortisol. Treatment groups were subdivided into three times of first treatment. These times were 2, 7, and 12 hours postpartum. The source of bovine IgG was a commercial colostrum supplement (Life Boost, Natur's Way Co., Oakland, NE) that contained 35 g of IgG per dose. All IgG treated calves received supplement from the same lot. Calves in the no IgG group were fed only a medicated milk replacer (Nurse Chow #100, Purina, St. Louis, MO). Cortisol (Hydrocortisone-11,17-alpha,21-trihydroxypregnen-4-ene-3,20-dione, Sigma Chemical Co., St. Louis, MO) was suspended in ethanol and injected subcutaneously. Injection volumes were approximately 1 ml to deliver 5 mg/kg of body weight. Animals not receiving cortisol received a sham injection of 1 ml ethanol subcutaneously.
For a calf to enter the experimental protocol, the time of parturition had to be observed. Each calf was immediately removed from its dam, dried with towels, weighed, and placed in an individual pen bedded with wood shavings. Each calf was given oral equine, E. coli antibodies (Sero-Guard 99, Bioceutic, St. Joseph, MO), and the navel was treated with tincture of iodine.
Blood samples were collected from the jugular vein at specified intervals to determine the changes of serum IgG concentration. The first sample was collected one-half hour after birth to confirm that the calves were without immunoglobulins. Additional blood samples were then collected just prior to the designated treatments, 2 and 12 hours after treatment, and finally 48 + 6 hours after birth.
At the designated time of treatment (2, 7, or 12 hours postpartum) each calf was given either the IgG supplement or milk replacer mixed in 1.9 liters of water. Treatments were offered in polyethylene bottles with rubber nipples. Calves that would not consume the entire volume were fed the remainder via an esophageal tube to assure equal intake. Upon completion of this feeding, the cortisol or sham injections were administered. Twelve hours after the time of experimental treatment, calves were offered colostrum from their dams. They were allowed to consume up to 1.9 liters or to satiation.
Health and weight data on the calves were kept for 42 days postpartum. For five weeks, the calves were fed milk at 8% of body weight, half at each of two daily feedings. At week six, feedings were reduced to once daily. At two weeks of age, the calves were given 0.20 kg of calf starter. As starter intake increased, the daily allocation of starter was increased. The amounts of feed each calf refused were recorded.
An enzyme linked immunosorbant assay (ELISA) was used to quantify the concentrations of IgG in serum samples. The assay used was developed by Schanbacher et al. (1993). Prior to analysis of IgG concentrations in serum from the experimental calves, a pilot study was conducted to confirm sensitivity and specificity of the assay in calves and to confirm the predicted response from experimental treatments. Four calves were used to confirm the assay. The assay proved to be sensitive to 1 ng/ml, Life Boost provided a reliable source of IgG, and neither Sero-Guard nor Nurse Chow #100 Medicated Milk Replacer provided IgG.
The data for calf weight gain and growth were analyzed by general linear models procedures for least squares analysis of variance (SAS, 1988). Body weight data from the nine treatments were analyzed for eight time periods (birth, weeks 1 through 6, and day 42 postpartum). The statistical model included treatment (Cortisol and IgG, Cortisol and no IgG, and Alcohol and IgG), period, sex, and interactions. The results were considered significantly different when P < 0.05.
Differences in immunoglobulin concentrations also were analyzed by general linear models procedures. The analysis included treatment (Cortisol and IgG, Cortisol and no IgG, and Alcohol and IgG), period (birth, feeding time, 2 hours post-feeding, 12 hours post-feeding, and 48 hours postpartum), treatment and feeding time (2, 7, and 12 hours postpartum, within each of the three treatment groups), and interactions. Treatments and feeding times were arranged as a 3 x 3 factorial within sample times. Two orthogonal comparisons also were used to compare the effects of IgG due to treatment and effects of cortisol dose. The results of this analysis were considered significantly different if P < 0.05.
The calves used in this experiment were all born between June 11, 1995, and August 18, 1995. The assay verification supplementary control calves were all born between September 19, 1995, and October 6, 1995. Therefore, no confounding effects from differing temperature and climactic conditions were noted. Extreme differences in the climate at birth could result in increased stress due to thermoregulation problems in the newborn, thus challenging its ability to adjust and adapt to its new environment.
All samples were taken as outlined by the protocol. There were no accidents, incidents, calf illnesses, or deaths that required any calf replacements. During the first 48 hours there were no health problems with any of the calves used in the experiment. Subsequently, some minimal health problems occurred, mainly diarrhea. The organism responsible for the diarrhea was isolated and identified as Cryptosporidium. All health problems were dealt with and treated by a veterinarian as needed.
Mean period weights for all of the calves on the experiment are shown in Figure 1. Bulls were significantly (P < 0.03) heavier at birth, but there were no significant differences between the sexes in their final 42-day weights (P > 0.24). Sex did not cause a significant difference on weight gain (P > 0.24). As expected, time affected the body weight of the calves. Treatments had no significant effect on the 42-day weight gain and growth of the calves (P > 0.76).
Figure 1. Mean birth , weeks 1 to 6, and final
42-day body weights (kg) of calves on the immunoglobulin experiment for
all treatment groups.
The final serum IgG concentrations between treatment groups and sampling times were significantly different (P < 0.001) (Figure 2). At birth (0.5 hours) the mean serum IgG concentrations for all treatment groups were 2.8 + 1.9 (standard error) mg/dl. Immediately prior to treatment and injection, the mean serum IgG concentrations for all treatment groups were 2.6 + 1.8 mg/dl. The serum IgG concentrations at these two times were similar, because both sampling times were prior to treatments.
Figure 2. Effect of treatment on serum IgG
concentrations (ng/dl standard error) of Holstein calves.
Serum IgG concentrations (at 2 hours post-treatment and 12 hours post-treatment, respectively) showed a clear response to treatment and feeding. There was very little change in the serum IgG concentrations in the calves that received milk replacer (no IgG). The calves on the milk replacer supplement had a mean serum IgG concentration of 3.4 + 3.3 mg/dl at 2 hours post-treatment, which were not different from pre-treatment concentrations (P > 0.31). Calves that received IgG showed increased (P < 0.02) serum IgG concentrations of 15.8 + 3.3 mg/dl. Twelve hours post-treatment the serum IgG concentrations of 8.26 + 8.1 mg/dl for calves fed milk replacer still were not significantly different (P > 0.32) from their pre-treatment values. By 12 hours, the IgG fed calves had serum IgG concentrations of 128.2 + 8.1 mg/dl, which were higher (P > 0.0001) than the previous sampling time. By 48 hours, there were no significant differences in serum IgG concentrations between the treatment groups that received IgG or milk replacer (P > 0.68). Mean IgG concentrations for the three treatment groups were: cortisol and IgG, 434.3 + 41.5 mg/dl; cortisol and milk replacer (no IgG), 340.0 + 41.5 mg/dl; and sham and IgG, 288.5 + 44.4 mg/dl. Orthogonal comparisons to partition cortisol and immunoglobulin effects revealed that the administration of cortisol significantly (P < 0.03) increased serum IgG concentrations, while the administration of alcohol did not affect the final serum IgG concentration.
The administration of cortisol significantly (P < 0.03) influenced the ability of the calf to absorb immunoglobulins (Figure 2). The final mean serum IgG concentrations of calves that were given a dose of cortisol were higher than the mean for calves not given cortisol. This agrees with results of Hough et al. (1990) for lambs and follows the trend that higher IgG absorption was associated with increased blood cortisol concentrations in calves (Cabello and Levieux, 1980). There were no significant differences (P > 0.91 and P > 0.23) between cortisol and non-cortisol calves at the 2-hour and 12-hour postinjection samples. However, by 48 hours postpartum, the cortisol effect was noticeable. The calves given milk replacer with cortisol had serum IgG concentrations that were similar to calves fed IgG 12 hours earlier with an injection of ethanol instead of cortisol. By 48 hours postpartum, the calves that had been administered cortisol had significantly higher (P < 0.03) serum IgG concentrations than the non-cortisol calves. Figure 3 shows the relationship between the mean serum IgG concentrations of all calves, depending on the time of the first feeding.
Figure 3. Effect of time of first feeding (2, 7, or
12 hours postpartum) on serum IgG concentrations (ng/dl) standard
error) in Holstein calves.
Changes in immunoglobulin absorption among the three colostrum feeding times (2, 7, and 12 hours postpartum) did not show the kinetics of intestinal gut closure that were expected (Stott et al., 1979 a,b; Stott and Fellah, 1983). According to Cruywagen (1990) and Perino et al. (1993), by 8 hours postpartum, the ability of the calf to effectively absorb immunoglobulins should have been reduced by 50%. By 48 hours postpartum, the mean serum IgG concentration for the calves fed at 7 hours postpartum were not significantly different than the calves fed at 2 hours postpartum. However, "gut closure" may have started to influence absorption of immunoglobulins at 12 hours postpartum. The mean serum IgG concentration at 48 hours postpartum for calves that were given their first feeding supplement at 12 hours postpartum were significantly lower (P < 0.04) than for the other two colostrum feeding times. These results showed that the process of intestinal closure did occur but did not occur as rapidly as reported (Stott, 1980; Stott and Fellah, 1983; Perino et al., 1993). This particularly was evident among the calves on the milk replacer treatments that actually were not fed any IgG until 14, 19, or 24 hours postpartum (Table 1). Absorption of IgG should have been sharply decreased by the delayed feeding of an IgG source. More studies done solely on gut closure need to be conducted before the actual kinetics of the process can be determined, but the race against closure may not be as big an obstacle for the calf to overcome as was once thought.
| Table 1. IgG serum concentrations at 48 hours postpartum in relation to the times of IgG intake. | |||||
|
Cortisol |
IgG sources | Serum | |||
| Life-boost | Colostrum | IgG | + | SE | |
| (Time, hr) | (mg/dl) | ||||
| 2 | 2 | 14 | 452.9 | + | 66.5 |
| 7 | 7 | 19 | 542.5 | + | 66.5 |
| 12 | 12 | 24 | 307.5 | + | 81.5 |
| 2 | . . . | 14 | 369.1 | + | 81.5 |
| 7 | . . . | 19 | 346.0 | + | 66.5 |
| 12 | . . . | 24 | 305.0 | + | 66.5 |
| . . . | 2 | 14 | 319.1 | + | 81.5 |
| . . . | 7 | 19 | 379.9 | + | 66.5 |
| . . . | 12 | 24 | 166.3 | + | 81.5 |
Additional studies are being conducted at the Ohio Agricultural Research and Development Center to better define the processes that influence the rate and amount of immunoglobulin absorption from the gut of the neonatal calf. Better definition of the mechanism, timing, and effective dose of cortisol is needed before this can be used as a therapeutic treatment to enhance immunoglobulin uptake.
The authors wish to thank OARDC Krauss Dairy Center employees John Durst, Alan Griffiths, Nancy Oliver, Kevin Snyder, and Ken Wise for their assistance, as well as student colleagues Joe Allen, Heather Keller, and Rachel Kosa. This work was the basis for the College of Wooster Independent Study Thesis of Suzanne Whitaker.
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