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Serum immunoglobulin concentrations of newborn goat kids and subsequent kid survival through weaning
SmallRuminantResearch, 11 (1993) 71-77
71
© 1993 Elsevier Science Publishers B.V. All rights reserved. 0921-4488/93/$06.00
Serum immunoglobulin concentrations of newborn goat kids and subsequent kid survival through weaning J.P. O ' B r i e n b a n d
D.M. Sherman a
aDepartment of Medicine, Tufts University School of Veterinary Medicine, North Grafton, MA, USA and bRiversideAnimal Hospital Ltd., Riverside, RI, USA (Accepted 21 September 1992 )
ABSTRACT Serum immunoglobulin (Ig) levels were measured in 39 consecutively newborn goat kids on an intensively managed dairy goat farm in New England using a quantitative, spectrophotometric zinc sulfate turbidity assay. The health and performance of these kids was monitored through weaning at 6-7 weeks of age. By weaning time, 24 kids were healthy, four had required treatment, and 11 had died. The mean serum Ig concentration for all kids was 1170 mg/dl. Mean serum Ig level for healthy kids was 1439 mg/dl, for treated kids, 706 mg/dl, and for dead kids, 750 mg/dl. There was a statistically significant difference in mean serum Ig levels between the group that died and the group that remained healthy (P< 0.05). No differences were observed in either death rates or mean serum Ig levels between male and female kids. Among kids that remained healthy through weaning, there was no identifiable correlation between initial serum lg concentration and average daily weight gain. It was concluded that the failure of passive transfer of maternal antibodies to kids via colostrum at birth leads to increased morbidity and mortality from infectious disease in young goats. Results from this study suggest that in intensively managed dairy goat herds in New England (USA), failure of passive transfer in newborn kids can be defined by the presence of circulating serum Ig levels less than 1200 mg/dl. Key words: Serum immunoglobulin level; Passive immunity transfer; Colostrum; Goat kids
INTRODUCTION
Newborn goats, like the young of other livestock species with a maternal syndesmochorial or epitheliochorial placentation, depend on the ingestion of antibody-rich colostrum shortly after birth to provide passive immunologic protection until they can actively produce their own array of protective antiCorrespondence to: D.M. Sherman, Department of Medicine, Tufts University School of Veterinary Medicine, 200 Westboro Road, North Grafton, MA, 01536, USA.
72
J.P. O'BRIEN AND D.M. SHERMAN
bodies. The failure to absorb adequate antibodies in the immediate post-part u m period can predispose to serious infectious disease problems and high mortality in neonates. Unacceptably high levels of death loss in young goats are recognized as a major constraint on goat production wherever goats are raised. Various factors contributing to kid death in goat-producing regions of the world have been reviewed (Sherman, 1987; Morand-Fehr, 1987). In extensive management systems, kid losses have been reported in the range of 10 to 60% and, in intensive management systems, from 8 to 17%. These deaths occur most frequently in the first few days of life. Numerous factors contribute to this early mortality, including low birth weight, short gestation period, large litter size, poor mothering, and hypothermia, as well as other environmental and weather conditions at the time of kidding. In addition, the failure to suckle adequate colostrum at birth contributes significantly to the preponderance of early kid deaths, most likely through the mechanism of failure of passive transfer of humoral immunity. In a French survey, 92% of colostrum-deprived kids that died did so within 2 days of birth (Morand-Fehr et al., 1984 ). In an Indian study, serum immunoglobulin (Ig) levels were measured in newborn kids 18 h after ingestion of colostrum and the mean serum Ig concentration of these kids was 735 mg/dl. In the following 2 months, mortality of kids with serum Ig levels below the mean was 44%, but was 3.8% for those with serum Ig levels above the mean ( N a n d a k u m a r and Rajagopalaraja, 1983). To date, there have been few reports on the relationship of kid survival and passive antibody (immunoglobulin) levels in goat kids in general, and no reports on goat kids raised under intensive management conditions in North America. The present report describes the relationship of Ig levels in newborn kids to their subsequent health and survival status in an intensively managed dairy goat herd in Massachusetts, USA. MATERIALS AND METHODS
Studyfarm All kids in this study were born on a commercial dairy goat farm in Seekonk, MA. The farm is approx. 2 ha in size, of which 1.2 ha are pasture. There are four separate barns; one houses milking does as well as buck kids destined for meat markets, one houses doe kids to be kept as replacements, one houses yearling does and the fourth is for breeding bucks. All barns are set up for loose housing with access to outside exercise yards. The milking herd is predominantly of the French Alpine breed, but a few LaMancha and Saanen does are also present. Buck kids born on the farm are sold for meat, usually after weaning at 6-7 weeks of age. These buck kids are fed raw colostrum at birth from a nipple
SERUM IMMUNOGLOBULIN CONCENTRATIONS OF NEWBORN GOAT KIDS
73
bottle, or are occasionally allowed to suckle the dams directly. The doe kids are fed heat-treated colostrum by nipple bottle in an effort to control caprine arthritis encephalitis infection (Adams et al., 1983 ). This colostrum is heated to 54.4°C and maintained at that temperature for 1 h.
Experimental protocol Forty-one kids, consecutively born between February and September 1990, were included in the study. The owner fed colostrum to these kids at or near the time of birth according to his usual practices and notified the investigators when kids were born. One of the investigators then visited the farm, examined and weighed the kid and obtained a blood sample by jugular venipuncture when the kid was between the age of 48-96 h. Serum was derived from blood samples by centrifugation within 12 h of collection, and the serum samples were frozen at - 2 0 °C for subsequent batch analysis of Ig content at the end of the study. The owner also notified the investigators when a kid became ill and required any kind of therapeutic intervention, or when a kid died. For each kid that died attempts were made, by gross necropsy examination performed by the investigators, to determine the cause of death. Records were kept of the number of kids that survived to weaning without treatment intervention (healthy group), with treatment intervention (treatment group ) or died prior to weaning (dead group). When possible, surviving kids were weighed once again between 5 and 7 weeks of age and an average daily weight gain calculated using the difference between this weight and the weight taken at the time of blood sampling. Determination of i g concentration Total Ig concentrations in kid sera were measured with a quantitative spectrophotometric zinc sulfate turbidity assay first described for calves (Pfeiffer et al., 1977 ) but modified and described for application to kid sera (Sherman et al., 1990). Analysis was performed on a Spectronic 20 spectrophotometer (Bausch and Lomb, Inc., Rochester, NY) in triplicate and an average absorbance calculated. The corresponding Ig concentrations were derived from a graph of the standard curve generated for caprine Ig and corrected for hemolysis as previously described (Pfeiffer et al., 1977). All statistical analyses were performed using a computer based statistical program (Statview, BrainPower, Calabasas, CA, 1989). RESULTS
Outcomes of kids Two of the 41 kids sampled were sold shortly after birth and were lost to follow up. Of the remaining 39 kids, 24 remained healthy, four required treat-
74
J.P. O'BRIENAND D.M. SHERMAN
ment but survived, and 11 died. The four treated kids were given either antibiotics for presumptive pneumonia or oral fluid/electrolyte therapy for diarrhea. A presumptive cause of death was determined in eight of the 11 dead kids. Pneumonia was the most commonly identified cause of death. Other individual causes identified included enteritis, septicemia, umbilical abscess and a case of enzootic muscular dystrophy.
Relationship of serum Ig level to kid outcome The number of healthy, treated, and dead kids, and the mean serum Ig levels for each group is given in Table 1. The difference in mean Ig levels between the healthy group and the dead group was statistically significant as determined by analysis of variance ( P < 0.05 ). There were no significant differences in mean Ig levels between the treated group and the healthy group or the treated group and the dead group. Relationship of serum Ig level to mean daily weight gain Of the 24 kids that remained healthy through weaning, 19 were available to be reweighed. The range of Ig levels in these 19 kids was 0.0 to 2783 mg/dl. The range of mean daily weight gains for these same kids was 80 to 200 g. There was no significant correlation between serum Ig levels and weight gain (r=0.086). Comparison between male and female kids The overall mortality rate was 11/39 (28.2%). The proportion of doe kids dying during the study was 6/16 ( 37.5% ) and that of buck kids 5/23 (21.7%) ( P > 0.05 ). There also was no significant difference between sexes in levels of colostral antibodies absorbed. The mean circulating serum Ig level for doe kids was 914 mg/dl and for buck kids 1352 mg/dl. TABLE 1 Post natal serum immunoglobulin (Ig) concentrations in kids that died, required treatment or remained healthy between birth and weaning Group
Number of kids
Mean Ig conc. (mg/dl)*
Standard deviation
Standard error
Range Ig conc. (mg/dl)
Dead Treated Healthy
11 4 24
750.7 a 706.3 ab 1439. lb
1026.9 821.4 898.6
309.6 410.7 183.4
0-3327 0-1533 0--2625
*Different letters indicate significant ( P < 0.05 ) differences in means.
SERUM IMMUNOGLOBULIN CONCENTRATIONS OF NEWBORN GOAT KIDS
75
DISCUSSION
It is well established that neonatal calves, foals and pigs are largely protected from early morbidity and mortality due to infectious disease by passive transfer of maternally derived antibodies in colostrum at the time of first suckling (Tizard, 1987). While this is presumed to be true in kids as well, confirmation by experimental or epidemiological studies in goats is limited. The present study, which shows a significantly higher mean serum Ig level in kids that survive to weaning compared to those that die, documents this phenomenon in young goats. The level of protective immunity afforded by maternal antibodies against infectious diseases in neonates is relative and not absolute. Numerous other factors act in the determination of whether or not individual animals succumb to infectious disease. A delicate balance exists between the susceptibility of the host to infectious agents and the potential infectivity of that agent. Management factors, such as indoor confinement, may increase potential environmental pathogen loads and tip the balance in favor of infection, even in neonates with maternal antibodies. It is difficult to pinpoint a uniformly protective concentration of serum Ig in neonates across a wide variety of species and management situations. A serum Ig concentration of at least 400 mg/dl is considered adequate for healthy foals raised in clean environments, but inadequate for foals with a heavy exposure to pathogens (McClure, 1990). Calves with equally low levels of serum Ig were much more likely to die when market-purchased and group-reared than when home-raised and single-penned (Naylor, 1979). In the present study, with home-raised kids grouped in loose housing, the mean serum Ig concentration of kids surviving to weaning age ( 1439 mg/dl ) was significantly higher than the mean serum Ig concentration of kids that died (750 mg/dl). Except for the one diagnosis of enzootic muscular dystrophy, all dead kids in which a presumptive necropsy diagnosis was possible had gross necropsy findings consistent with typical infectious disease problems of the perinatal period such as pneumonia, enteritis, septicemia and umbilical abscesses. Mean serum Ig concentration for all 39 kids in the study was 1170 mg/dl. Death rate for kids with serum Ig concentrations below the overall mean was 8/17 or 47.0%, while the death rate for kids with serum Ig concentrations above the overall mean was 13.6%. This difference in death rates is similar to that reported for goat kids in India (Nandakumar and Rajagopalaraja, 1983 ). However, the mean Ig concentration in Indian kids was considerably lower at 735 mg/dl. This underscores that a single standard for defining failure of passive transfer should not be applied across diverse geographic, climatic or management settings. The fact that some individual kids in our study with Ig levels well above the mean died, while other individuals with Ig levels well
76
.I.P. O'BRIEN A N D D.M. SHERMAN
below the mean remained healthy, further emphasizes that factors other than passive transfer of maternal antibodies affect survival. The high overall kid death rate on this farm ( 2 8 % ) suggests that the challenge by pathogenic organisms was particularly high. N o differences between male and female kids were noted in death rates or mean serum Ig concentrations. This is not surprising, as a thorough review o f the literature on kid mortality could not identify a consistent sex bias for kid survival (Sherman, 1987). On this farm, doe kids were fed colostrum that was heat-treated in order to eliminate the retrovirus causing caprine arthritis encephalitis, while buck kids, destined for sale to the meat market, were fed raw, untreated colostrum. The lack o f statistically significant differences in m e a n Ig concentrations or death rates between male and females suggests, at least indirectly, that heat treatment of colostrum to 54.5 °C for 1 h does not degrade immunoglobulins or impair their i m m u n o p r o t e c t i v e qualities. In conclusion, this study confirms that kid health and survival are associated with the passive transfer o f maternal antibodies via colostrum at birth and that higher levels o f circulating serum Ig provide greater protection against infectious diseases. U n d e r intensive management conditions in the northeastern USA, the study suggests that a m i n i m u m of 1200 m g / d l of serum Ig should be achieved in n e w b o r n kids to help insure good health and survival to weaning. ACKNOWLEDGEMENTS This research was funded by a grant from the Southern Vermont Dairy Goat Association, Inc., West Brattleboro, VT, 05301. The authors thank Mr. Joe L o m b a r d i for allowing this study to be carried out in his goat herd.
REFERENCES Adams, D.S., Klevjer-Anderson, P., Carlson, J.L., McGuire, T.C. and Gorham, J.R., 1983. Transmission and control ofcaprine arthritis-encephalitis virus. Am. J. Vet. Res., 44: 16701675. McClure, J.J., 1990. Equine immunodeficiency diseases. In: B.P. Smith (Editor), Large Animal Internal Medicine, C.V. Mosby Co., St. Louis, pp. 1598-1610. Morand-Fehr, P., 1987. Management programs for the prevention of kid losses. Proc. IV International Conf. Goats, EMBRAPA-DDT, Brasilia, Brazil, pp. 405-423. Morand-Fehr, P., Villette, Y. and Chemineau, P., 1984. Influenced des conditions de milieu sur la mortalite des chevreaux (Influence of environmental conditions upon the mortality of goats ). In: P. Yvore and G. Perrin ( Editors ), Les maladies de la chevre (Diseases of Goats ). Les Colloques de I'INRA, No. 28, Institut National de la Recherche Agronomique, Paris, pp. 31-46. Nandakumar, P. and Rajagopalaraja, C.A., 1983. Growth and mortality in relation to serum immunoglobulin level in neonatal kids. Kerala J. Vet. Sci., 14: 49-52.
SERUM IMMUNOGLOBULIN CONCENTRATIONS OF NEWBORN GOAT KIDS
77
Naylor, J.M., 1979. Colostral immunity in the calf and the foal. Vet. Clin. N. Am.: Large Anim. Pract., 1: 331-361. Pfeifer, N.E., McGuire, T.C., Bendel, R.B. and Weikel, J.M., 1977. Quantitation of bovine immunoglobulins: comparison of single radial immunodiffusion, zinc sulfate turbidity, serum electrophoresis, and refractometer methods. Am. J. Vet. Res., 38: 693-698. Sherman, D.M., 1987. Causes of kid morbidity and mortality: An overview. Proceedings, IV International Conf. Goats, EMBRAPA-DDT, Brasilia, Brazil, pp. 335-354. Sherman, D.M., Arendt, T.D., Gay, J.M. and Maefsky, V.A., 1990. Comparing the effects of four colostral preparations on serum Ig levels of newborn kids. Vet. Med., 85:908-913. Tizard, I., 1987. Veterinary Immunology. An Introduction. 3rd Edn., W.B. Saunders Co., Philadelphia, 401 pp.
71
© 1993 Elsevier Science Publishers B.V. All rights reserved. 0921-4488/93/$06.00
Serum immunoglobulin concentrations of newborn goat kids and subsequent kid survival through weaning J.P. O ' B r i e n b a n d
D.M. Sherman a
aDepartment of Medicine, Tufts University School of Veterinary Medicine, North Grafton, MA, USA and bRiversideAnimal Hospital Ltd., Riverside, RI, USA (Accepted 21 September 1992 )
ABSTRACT Serum immunoglobulin (Ig) levels were measured in 39 consecutively newborn goat kids on an intensively managed dairy goat farm in New England using a quantitative, spectrophotometric zinc sulfate turbidity assay. The health and performance of these kids was monitored through weaning at 6-7 weeks of age. By weaning time, 24 kids were healthy, four had required treatment, and 11 had died. The mean serum Ig concentration for all kids was 1170 mg/dl. Mean serum Ig level for healthy kids was 1439 mg/dl, for treated kids, 706 mg/dl, and for dead kids, 750 mg/dl. There was a statistically significant difference in mean serum Ig levels between the group that died and the group that remained healthy (P< 0.05). No differences were observed in either death rates or mean serum Ig levels between male and female kids. Among kids that remained healthy through weaning, there was no identifiable correlation between initial serum lg concentration and average daily weight gain. It was concluded that the failure of passive transfer of maternal antibodies to kids via colostrum at birth leads to increased morbidity and mortality from infectious disease in young goats. Results from this study suggest that in intensively managed dairy goat herds in New England (USA), failure of passive transfer in newborn kids can be defined by the presence of circulating serum Ig levels less than 1200 mg/dl. Key words: Serum immunoglobulin level; Passive immunity transfer; Colostrum; Goat kids
INTRODUCTION
Newborn goats, like the young of other livestock species with a maternal syndesmochorial or epitheliochorial placentation, depend on the ingestion of antibody-rich colostrum shortly after birth to provide passive immunologic protection until they can actively produce their own array of protective antiCorrespondence to: D.M. Sherman, Department of Medicine, Tufts University School of Veterinary Medicine, 200 Westboro Road, North Grafton, MA, 01536, USA.
72
J.P. O'BRIEN AND D.M. SHERMAN
bodies. The failure to absorb adequate antibodies in the immediate post-part u m period can predispose to serious infectious disease problems and high mortality in neonates. Unacceptably high levels of death loss in young goats are recognized as a major constraint on goat production wherever goats are raised. Various factors contributing to kid death in goat-producing regions of the world have been reviewed (Sherman, 1987; Morand-Fehr, 1987). In extensive management systems, kid losses have been reported in the range of 10 to 60% and, in intensive management systems, from 8 to 17%. These deaths occur most frequently in the first few days of life. Numerous factors contribute to this early mortality, including low birth weight, short gestation period, large litter size, poor mothering, and hypothermia, as well as other environmental and weather conditions at the time of kidding. In addition, the failure to suckle adequate colostrum at birth contributes significantly to the preponderance of early kid deaths, most likely through the mechanism of failure of passive transfer of humoral immunity. In a French survey, 92% of colostrum-deprived kids that died did so within 2 days of birth (Morand-Fehr et al., 1984 ). In an Indian study, serum immunoglobulin (Ig) levels were measured in newborn kids 18 h after ingestion of colostrum and the mean serum Ig concentration of these kids was 735 mg/dl. In the following 2 months, mortality of kids with serum Ig levels below the mean was 44%, but was 3.8% for those with serum Ig levels above the mean ( N a n d a k u m a r and Rajagopalaraja, 1983). To date, there have been few reports on the relationship of kid survival and passive antibody (immunoglobulin) levels in goat kids in general, and no reports on goat kids raised under intensive management conditions in North America. The present report describes the relationship of Ig levels in newborn kids to their subsequent health and survival status in an intensively managed dairy goat herd in Massachusetts, USA. MATERIALS AND METHODS
Studyfarm All kids in this study were born on a commercial dairy goat farm in Seekonk, MA. The farm is approx. 2 ha in size, of which 1.2 ha are pasture. There are four separate barns; one houses milking does as well as buck kids destined for meat markets, one houses doe kids to be kept as replacements, one houses yearling does and the fourth is for breeding bucks. All barns are set up for loose housing with access to outside exercise yards. The milking herd is predominantly of the French Alpine breed, but a few LaMancha and Saanen does are also present. Buck kids born on the farm are sold for meat, usually after weaning at 6-7 weeks of age. These buck kids are fed raw colostrum at birth from a nipple
SERUM IMMUNOGLOBULIN CONCENTRATIONS OF NEWBORN GOAT KIDS
73
bottle, or are occasionally allowed to suckle the dams directly. The doe kids are fed heat-treated colostrum by nipple bottle in an effort to control caprine arthritis encephalitis infection (Adams et al., 1983 ). This colostrum is heated to 54.4°C and maintained at that temperature for 1 h.
Experimental protocol Forty-one kids, consecutively born between February and September 1990, were included in the study. The owner fed colostrum to these kids at or near the time of birth according to his usual practices and notified the investigators when kids were born. One of the investigators then visited the farm, examined and weighed the kid and obtained a blood sample by jugular venipuncture when the kid was between the age of 48-96 h. Serum was derived from blood samples by centrifugation within 12 h of collection, and the serum samples were frozen at - 2 0 °C for subsequent batch analysis of Ig content at the end of the study. The owner also notified the investigators when a kid became ill and required any kind of therapeutic intervention, or when a kid died. For each kid that died attempts were made, by gross necropsy examination performed by the investigators, to determine the cause of death. Records were kept of the number of kids that survived to weaning without treatment intervention (healthy group), with treatment intervention (treatment group ) or died prior to weaning (dead group). When possible, surviving kids were weighed once again between 5 and 7 weeks of age and an average daily weight gain calculated using the difference between this weight and the weight taken at the time of blood sampling. Determination of i g concentration Total Ig concentrations in kid sera were measured with a quantitative spectrophotometric zinc sulfate turbidity assay first described for calves (Pfeiffer et al., 1977 ) but modified and described for application to kid sera (Sherman et al., 1990). Analysis was performed on a Spectronic 20 spectrophotometer (Bausch and Lomb, Inc., Rochester, NY) in triplicate and an average absorbance calculated. The corresponding Ig concentrations were derived from a graph of the standard curve generated for caprine Ig and corrected for hemolysis as previously described (Pfeiffer et al., 1977). All statistical analyses were performed using a computer based statistical program (Statview, BrainPower, Calabasas, CA, 1989). RESULTS
Outcomes of kids Two of the 41 kids sampled were sold shortly after birth and were lost to follow up. Of the remaining 39 kids, 24 remained healthy, four required treat-
74
J.P. O'BRIENAND D.M. SHERMAN
ment but survived, and 11 died. The four treated kids were given either antibiotics for presumptive pneumonia or oral fluid/electrolyte therapy for diarrhea. A presumptive cause of death was determined in eight of the 11 dead kids. Pneumonia was the most commonly identified cause of death. Other individual causes identified included enteritis, septicemia, umbilical abscess and a case of enzootic muscular dystrophy.
Relationship of serum Ig level to kid outcome The number of healthy, treated, and dead kids, and the mean serum Ig levels for each group is given in Table 1. The difference in mean Ig levels between the healthy group and the dead group was statistically significant as determined by analysis of variance ( P < 0.05 ). There were no significant differences in mean Ig levels between the treated group and the healthy group or the treated group and the dead group. Relationship of serum Ig level to mean daily weight gain Of the 24 kids that remained healthy through weaning, 19 were available to be reweighed. The range of Ig levels in these 19 kids was 0.0 to 2783 mg/dl. The range of mean daily weight gains for these same kids was 80 to 200 g. There was no significant correlation between serum Ig levels and weight gain (r=0.086). Comparison between male and female kids The overall mortality rate was 11/39 (28.2%). The proportion of doe kids dying during the study was 6/16 ( 37.5% ) and that of buck kids 5/23 (21.7%) ( P > 0.05 ). There also was no significant difference between sexes in levels of colostral antibodies absorbed. The mean circulating serum Ig level for doe kids was 914 mg/dl and for buck kids 1352 mg/dl. TABLE 1 Post natal serum immunoglobulin (Ig) concentrations in kids that died, required treatment or remained healthy between birth and weaning Group
Number of kids
Mean Ig conc. (mg/dl)*
Standard deviation
Standard error
Range Ig conc. (mg/dl)
Dead Treated Healthy
11 4 24
750.7 a 706.3 ab 1439. lb
1026.9 821.4 898.6
309.6 410.7 183.4
0-3327 0-1533 0--2625
*Different letters indicate significant ( P < 0.05 ) differences in means.
SERUM IMMUNOGLOBULIN CONCENTRATIONS OF NEWBORN GOAT KIDS
75
DISCUSSION
It is well established that neonatal calves, foals and pigs are largely protected from early morbidity and mortality due to infectious disease by passive transfer of maternally derived antibodies in colostrum at the time of first suckling (Tizard, 1987). While this is presumed to be true in kids as well, confirmation by experimental or epidemiological studies in goats is limited. The present study, which shows a significantly higher mean serum Ig level in kids that survive to weaning compared to those that die, documents this phenomenon in young goats. The level of protective immunity afforded by maternal antibodies against infectious diseases in neonates is relative and not absolute. Numerous other factors act in the determination of whether or not individual animals succumb to infectious disease. A delicate balance exists between the susceptibility of the host to infectious agents and the potential infectivity of that agent. Management factors, such as indoor confinement, may increase potential environmental pathogen loads and tip the balance in favor of infection, even in neonates with maternal antibodies. It is difficult to pinpoint a uniformly protective concentration of serum Ig in neonates across a wide variety of species and management situations. A serum Ig concentration of at least 400 mg/dl is considered adequate for healthy foals raised in clean environments, but inadequate for foals with a heavy exposure to pathogens (McClure, 1990). Calves with equally low levels of serum Ig were much more likely to die when market-purchased and group-reared than when home-raised and single-penned (Naylor, 1979). In the present study, with home-raised kids grouped in loose housing, the mean serum Ig concentration of kids surviving to weaning age ( 1439 mg/dl ) was significantly higher than the mean serum Ig concentration of kids that died (750 mg/dl). Except for the one diagnosis of enzootic muscular dystrophy, all dead kids in which a presumptive necropsy diagnosis was possible had gross necropsy findings consistent with typical infectious disease problems of the perinatal period such as pneumonia, enteritis, septicemia and umbilical abscesses. Mean serum Ig concentration for all 39 kids in the study was 1170 mg/dl. Death rate for kids with serum Ig concentrations below the overall mean was 8/17 or 47.0%, while the death rate for kids with serum Ig concentrations above the overall mean was 13.6%. This difference in death rates is similar to that reported for goat kids in India (Nandakumar and Rajagopalaraja, 1983 ). However, the mean Ig concentration in Indian kids was considerably lower at 735 mg/dl. This underscores that a single standard for defining failure of passive transfer should not be applied across diverse geographic, climatic or management settings. The fact that some individual kids in our study with Ig levels well above the mean died, while other individuals with Ig levels well
76
.I.P. O'BRIEN A N D D.M. SHERMAN
below the mean remained healthy, further emphasizes that factors other than passive transfer of maternal antibodies affect survival. The high overall kid death rate on this farm ( 2 8 % ) suggests that the challenge by pathogenic organisms was particularly high. N o differences between male and female kids were noted in death rates or mean serum Ig concentrations. This is not surprising, as a thorough review o f the literature on kid mortality could not identify a consistent sex bias for kid survival (Sherman, 1987). On this farm, doe kids were fed colostrum that was heat-treated in order to eliminate the retrovirus causing caprine arthritis encephalitis, while buck kids, destined for sale to the meat market, were fed raw, untreated colostrum. The lack o f statistically significant differences in m e a n Ig concentrations or death rates between male and females suggests, at least indirectly, that heat treatment of colostrum to 54.5 °C for 1 h does not degrade immunoglobulins or impair their i m m u n o p r o t e c t i v e qualities. In conclusion, this study confirms that kid health and survival are associated with the passive transfer o f maternal antibodies via colostrum at birth and that higher levels o f circulating serum Ig provide greater protection against infectious diseases. U n d e r intensive management conditions in the northeastern USA, the study suggests that a m i n i m u m of 1200 m g / d l of serum Ig should be achieved in n e w b o r n kids to help insure good health and survival to weaning. ACKNOWLEDGEMENTS This research was funded by a grant from the Southern Vermont Dairy Goat Association, Inc., West Brattleboro, VT, 05301. The authors thank Mr. Joe L o m b a r d i for allowing this study to be carried out in his goat herd.
REFERENCES Adams, D.S., Klevjer-Anderson, P., Carlson, J.L., McGuire, T.C. and Gorham, J.R., 1983. Transmission and control ofcaprine arthritis-encephalitis virus. Am. J. Vet. Res., 44: 16701675. McClure, J.J., 1990. Equine immunodeficiency diseases. In: B.P. Smith (Editor), Large Animal Internal Medicine, C.V. Mosby Co., St. Louis, pp. 1598-1610. Morand-Fehr, P., 1987. Management programs for the prevention of kid losses. Proc. IV International Conf. Goats, EMBRAPA-DDT, Brasilia, Brazil, pp. 405-423. Morand-Fehr, P., Villette, Y. and Chemineau, P., 1984. Influenced des conditions de milieu sur la mortalite des chevreaux (Influence of environmental conditions upon the mortality of goats ). In: P. Yvore and G. Perrin ( Editors ), Les maladies de la chevre (Diseases of Goats ). Les Colloques de I'INRA, No. 28, Institut National de la Recherche Agronomique, Paris, pp. 31-46. Nandakumar, P. and Rajagopalaraja, C.A., 1983. Growth and mortality in relation to serum immunoglobulin level in neonatal kids. Kerala J. Vet. Sci., 14: 49-52.
SERUM IMMUNOGLOBULIN CONCENTRATIONS OF NEWBORN GOAT KIDS
77
Naylor, J.M., 1979. Colostral immunity in the calf and the foal. Vet. Clin. N. Am.: Large Anim. Pract., 1: 331-361. Pfeifer, N.E., McGuire, T.C., Bendel, R.B. and Weikel, J.M., 1977. Quantitation of bovine immunoglobulins: comparison of single radial immunodiffusion, zinc sulfate turbidity, serum electrophoresis, and refractometer methods. Am. J. Vet. Res., 38: 693-698. Sherman, D.M., 1987. Causes of kid morbidity and mortality: An overview. Proceedings, IV International Conf. Goats, EMBRAPA-DDT, Brasilia, Brazil, pp. 335-354. Sherman, D.M., Arendt, T.D., Gay, J.M. and Maefsky, V.A., 1990. Comparing the effects of four colostral preparations on serum Ig levels of newborn kids. Vet. Med., 85:908-913. Tizard, I., 1987. Veterinary Immunology. An Introduction. 3rd Edn., W.B. Saunders Co., Philadelphia, 401 pp.