Hypoxia in Neonatal Calves: Effect on Intestinal Transport of Immunoglobulins HOWARD TYLER and HAROLD RAMSEY Department of Animal Science North Carolina State University Raleigh 27695-76a
maglobulinemic (8, 16, 24). The calf is, therefore, completely reliant on passive immunizaThe effect of reduced oxygen tension tion via Ig concentrated in colostrum. in arterial blood (hypoxic hypoxia) for Antibody absorption in calves is nonselec24 h postpartum on the absorption of tive and depends on amount of colostrum incolostral Ig was studied in 12 neonatal gested (3, %), amount of Ig in the ingested calves. During this period, inspired air colostrum (5, 15) and time elapsed between for hypoxic calves contained 10.5% 0 2 , birth and first feeding (14, 15). Cessation of whereas that for normoxic calves conintestinal transport of Ig (closure) occurs spontained 21% 0 2 . After 24 h, inspired air taneously in the calf (26). It is a gradually for all calves contained 21% 02. Three accelerating process that normally is comdietary regimens also were imposed durpleted between 12 and 36 h postpartum (14, ing the initial 24-h period: colostrum at 0 26). Approximately 25% of all calves remain and 12 h, whole milk at 0 and 12 h, or hypogammaglobulinemic despite intake of fasting. Colostrum was fed to all calves colostrum (12, 18, 25). Impaired performance at 24, 36, and 48 h. (7,22) and high mortality (18, 19,24) among During the initial 24-h period, means these animals illustrates the importance of for arterial partial pressure of oxygen elucidating mechanisms controlling the closure were 26 and 73 mm Hg for hypoxic and process with the ultimate goal of manipulating normoxic calves, respectively. In those these factors in a beneficial manner. fed colostrum at 0 and 12 h, hypoxia Oxygen consumption of the newborn inextended the period of Ig absorption cremes threefold above fetal levels in the first from 20 to 40.5 h. In calves fed whole 2 d (6), with much of this increase Occurring in milk or those that were fasted, no such the first 12 h (1). This is due in large part to effect was noted. These observations energy expenditures for maintenance of thersuggest that the effect of hypoxia on the mal neutrality (2,6,17). Activity of the gastrocessation of Ig absorption by the small intestinal tract also contributes to a significant intestine is mediated through a secondary extenc oxygen consumption rises 3.5-fold in and as yet undetermined mechanism. postnatal intestinal tissue at rest (10, 21) and (Key words: calves, immunoglobulins, increasing an additional 65 to 72% during hypoxia) digestion (4, 9). The primary objective of this experiment, Abbreviation key: p 0 2 = partial pressure of therefore, was to determine whether hypoxia oxygen, pC02 = partial pressure of carbon during the newborn period, i.e., maintaining dioxide. ) arterial partial pressure of oxygen ( ~ 0 2 near fetal levels, would delay the time of closure in INTRODUCTION the calf. Due to the absence of transplacental transfer MATERIALS AND METHODS of antibodies from maternal to fetal circulation, newborn calves are born essentially agamTwelve Holstein calves were assigned at birth to both a primary treatment (level of inspired oxygen) and secondary treatment (dietary regimen). Hypoxia was imposed Received October 15, 1990. within 2 min postpartum by providing calves a Accepted January 4, 1991. ABSTRACT
1991 J Dairy Sci 741952-1956
1953
1954
TYLER AND RAMSEY
1:l mixture of air and N2 via a face mask Fractional percentage of oxygen in the inspired gas mixture for hypoxic calves was 10.5%.A 30-L neoprene gas bag in the gas delivery system facilitated mixing of the gases as well as visualization of gas consumption. Flow rate was adjusted to the needs of individual calves. The duration of hypoxia was 24 h, at which time the use of a face mask was discontinued. Inspired air for nonnoxic calves, as well as hypoxic calves after 24 h, contained 21% oxygen. Oxygen content of inspired gases was determined twice daily using a Bacharach Fyrite oxygen analyzer (Bacharach Instruments, Pittsburgh, PA). A face mask was not used on normoxic calves during the initial 2 4 4 period. Dietary treatments superimposed upon the primary treatment during the initial 24-h pe riod were as follows: 1 kg of colostrum at 0 and 12 h, 1 kg of whole milk at 0 and 12 h, and fasting. All calves were fed 1 kg of colostrum at 24,36, and 48 h and2 kg of milk at 60 and 72 h. To ensure complete and uniform delivery of colostrum and milk, an esophageal feeder was utilized at all feedings. A pooled source of colostrum was used for all calves. Arterial blood was obtained two to three times daily by puncture from either the ventral coccygeal or carotid arteries, the choice depending on the physical position of the calf at the time of sampling. Samples were analyzed on an Instrumentation Laboratories System 1302 (Instrumentation Laboratories, Lexington, MA) blood gas system for determination of blood gas values. Values for arterial p@ during the initial 2 4 4 period are summarized in this paper. A detailed presentation of partial pressure of C02 ( p C 0 3 , and HCO; is made in a companion paper (27). Venous blood was sampled from the jugular vein at birth and at 6-h intervals through 48 h and again at 60 and 72 h. Samples at 0,12,24, 36, 48, 60, and 72 h were taken immediately prior to feeding. Plasma was separated by centrifugation at 1286 x g for 15 min and stored at -2O'C. Concentrations of IgG were quantitated via radial immunodiffusion with commercial gels (ICN Biomedicals, Inc., Costa Mesa, CA). Time of closure was estimated by calculating the join point as described by Hudson (13) and subsequently modified by Stott et al. (26). This procedure relies on the gradual decline in
m,
Journal of Dairy Science Vol. 74, No. 6, 1991
plasma IgG following cessation of transport, which reflects both catabolism of IgG and its transfer to extravascular pools (5). Thus, the resulting IgG concentration pattern in calves fed colostrum over the first 72 h describes a parabolic curve. By eliminating data points not occurring during the linear phase of absorption, the resulting observations can be fitted to two first-order regression lines. The intersection of these lines defines the join point, the estimate for time of closure. Sampling of blood, therefore, must be continued postclosure to satisfy requirements for both regression equations. All data were analyzed using the general linear models procedure of SAS (23). The statistical model included treatment, time, and calf effects. Significance of differences be tween means was determined by the method of least squares means using ANOVA. In all cases, probabilities greater than .05 were not considered significant, and results are reported accordingly. RESULTS AND DISCUSSION
The primary goal of the hypoxic treatment was to maintain arterial Po, near prenatal levels to prevent postnatal changes triggered by increased oxygen tension occuning at parturition. Published values for arterial Po, in the fetal calf vary from 19.5 (11) to 29.5 mm Hg (20), depending on sampling site and use of anaesthesia. Therefore, based on values obtained in this experiment (Po, = 26 nun Hg), our procedure for inducing hypoxia was successful. Values for normoxic calves during the
2000 T
,
0
6
1 2 18 2 4 30 36 42 48
0 normoxic
60
72
Age ( h )
Figure 1. Effect of hypoxia on absorption of IgG @ f SEW in newborn calves fed colostrum.
HYPOXIA AND CLOSURE IN NEWBORN C A L W
0normoxic EX3 hypoxic
Colostrum
Milk
Fasted
Figye 2. Effect of hypoxia and diet on peak plasma IgG (X f SEM) in newborn calves.
same period were substantially higher (PO, 73 mm Hg). Absorption of IgG in normoxic calves fed colostrum followed a typical absorptive pattern, relatively slow during the first 12 h and comparatively rapid after the second feeding a! 12 h (Figure 1). Due to the progressive nature of the closure process, only slight absorption occurzed between 18 and 24 h. Subsequent feedings of colostrum elicited no further increase in plasma IgG, indicating intestinal closure was complete prior to 24 h. In contrast to normoxic calves, absorption in hypoxic calves fed colostrum was slower during the first 18 h, with no apparent stimulation of absorptive function due to the second feeding (Figure 1). Rate of absorption increased dramatically after 18 h, and IgG levels did not diminish until between 42 and 48 h. The 48-h feeding of colostrum had no effect on plasma IgG. Absorptive capacity, as determined by the highest level of plasma IgG obtained, was unaffected by hypoxia. Extension of the absorptive period prior to closure without affecting capacity was accomplished by the diminished rate of absorption apparent during hypoxia, although high variation b e tween calves precludes any definite conclusions. The primary focus of this experiment was to determine the effects of hypoxia on time of closure in the newborn calf. When colostrum was fed at 0 and 12 h, time of closure was significantly delayed (P = .02) from 20 h in nonnoxic calves to 40.5 h in hypoxic calves. This developmental delay was not apparent in calves that were fasted or fed milk Minimal f:
1955
levels of IgG attained by calves that were fasted or fed milk relative to those fed colostnun suggest that closure was virtually complete by 24 h in both groups (Figure 2). The reasons for differences between dietary regimens are not readily apparent, but they suggest that the change in oxygen tension at biah is not the primary mediator of closure. There may be other mechanisms independent of changes in oxygen tension involved in the timing of closure in the calf. REFERENCES 1 Acheson, G. H., G. S. Daws, and J. C. Moa. 1957. Oxygen consumption and the arterial oxygen saturation in foetal and new-born lambs. J. PhysioL 135:623. 2Alexander, G. 1975. Body temperature control in maumahn young. Br. Med. Bull. 31:62. 3 A . s c b a f f ~ g , R., S. Bartlett, S. K. Kon, S. Y. Thompson, D. M. Walker,C. Briggs, E. Cotchin, and R b e l l . 1W9.Ibe nutritive significance of coloshum for the calf. Page 90 in Roc. 12th Int D airy congr. slockholm, Sweden. 4Brodie. T. G., W. C. Cullis, and W. D. Halliiurton. 1910. The gaseous metabolism of the small intestine. part II. Ibe gaseous exchanges during the absorption of Witte's peptone. J. Physiol. a . 1 7 3 . SBush,L. J.,M. A.Agailera, G. D.Adams,andE. W. Jonw. 1971. Absorption of colostal immmoglobulins by newborn dairy calves. J. Dairy Sci. 54:1547. 6Daws. G. S., and I. C. Moa. 1959. The increase in oxygen consumption of the lamb after birth. J. Physiol. 146:295. 7DeNiSe, S. K., J. D. ROb&OJl,G. H. Stott, and D. V. Amstrong. 1989. Effects of passive immunity on subsequent production in dairy heifers. I. Dairy Sci 72552. 8 -le, I. P. 1935. Influence of the ingestion of colostrum on the proteins of the blood sera of young foals, kids, lambs, and pigs. J. Agric. Res. 51:479. 9Edelstone. D. I., and I. R. Holpnan. 1981. Oxygen consumption by the gastrointestinal tract and liver in conscious newborn lambs. Am. J. Physiol. 2ru)..G297. l o E d e m , D. I., and I. R. Holzmaa 1981. Gastrointestinal tract 0, uptake and regional blood flows dnring digestion in conscious newborn lambs. Am. J. Physiol. 241:G289. 11Eigcmnann. V.UJB., E. Gruner& and U. Koppe. 1981. Znr spatasphyxie des kalbes. Bal. Muench. T i . w w a l l r . 94249. 12Gay, C. C., T. C. MCGujre, and S. M. Parish. 1983. Seasonal variation in passive transfer of imamnoglob ulin GI to newborn calves. J. Am. Vet. Med. Assoc. 183:566. 13 Hudson, D. J. 1966. Fitting segmented m e s whose pin points have to be estimated. J. Am. Stat. Assoc. 61:1097. 14 Jeffcott, L. B. 1974. Studies on passive immunity in the foal. II. he a m t i o n of '25I-la~edWP (polyvinyl pyrrolidonc) by the nconatal intestine. J. Comp. Pathol. W279. 15 Krose, V. 1970. Absorption of imtnunoglobuljn from
Jomnal of Dairy Science Vol. 74, No. 6, 1991
1956
TYLER AND RAMSEY
colostrum in newborn calves. Anim. Rod. 12:627. 16 M . 'I,M.J.G.S. 1971. Serum immunoglobulinsin newborn d v e s before and after colosmun feeding. Can. J. Comp. Med. 35269. 17Monnt, L. E. 1958. The oxygen consumption of the new-born pig in relation to enviroanental temperahue. J. Physiol. 142:37P. 18 Naylor, J. M.1979. Coloslral immunity in the calf and the foal. Vet. Clin. N.Am. Large Anim. Ract. 1:331. 19 Nocek, J. E., D. G. Braund, and R. G. Warner. 1984. Influence of neonatal colostrum admiuismtion, immunoglobdin, and continued feeding of colostram on calf gain, health, and semm protein. J. Dairy Sci. 6 7 319. 20Reeves, J. T., P. S. Daoud, and M. Gentry. 1972. Growth of the fetal calf and its arterial pressure, blood gases. and hematologic data. J. Awl. Physiol. 32240. 21Reeves, 1. T., and J. E. Leathers. 1964. Circalatory changes following birth of the calf and the effect of
Journal of Dairy Science Vol. 74. No. 6. 1991
hypoxia. Circ. Res. 15:343. 22Robison, J. D.. G. H. Stott, and S. K. DeNise. 1988. Effects of passive immunity on growth and survival in the dairy h e i f e r . J. Dairy Sci. 71:1283. 23SASQDUser's Guide: Statistics, Version 5 Edition. 1985. SAS Inst., Inc., Cary, NC. 24Smith, E. L., and A. Holm. 1948. The transfer of immunity to the new-born calf from colostrum. J. Biol. Chcm. 175349. UStaley, T. E., E. W. Jones, and L. J. Bush. 1971. Maternal transport of immunoglobulins to the calf. I. Dairy Sci. W1323. 26Stott, G. H., D. B. Marx, B. E. Menefee, and G. T. Nightengale. 1979. Colostral immunoglobulintransfer in cahres. 1. Period of absorption. J. Dairy Sci. 6 2 1632. 27Tyler, H. D., and H. A. Ramsey. 1991. Hypoxia in neonatal calves: effect on selected metabolic parameters. I. Dairy Sci. 741957.
maglobulinemic (8, 16, 24). The calf is, therefore, completely reliant on passive immunizaThe effect of reduced oxygen tension tion via Ig concentrated in colostrum. in arterial blood (hypoxic hypoxia) for Antibody absorption in calves is nonselec24 h postpartum on the absorption of tive and depends on amount of colostrum incolostral Ig was studied in 12 neonatal gested (3, %), amount of Ig in the ingested calves. During this period, inspired air colostrum (5, 15) and time elapsed between for hypoxic calves contained 10.5% 0 2 , birth and first feeding (14, 15). Cessation of whereas that for normoxic calves conintestinal transport of Ig (closure) occurs spontained 21% 0 2 . After 24 h, inspired air taneously in the calf (26). It is a gradually for all calves contained 21% 02. Three accelerating process that normally is comdietary regimens also were imposed durpleted between 12 and 36 h postpartum (14, ing the initial 24-h period: colostrum at 0 26). Approximately 25% of all calves remain and 12 h, whole milk at 0 and 12 h, or hypogammaglobulinemic despite intake of fasting. Colostrum was fed to all calves colostrum (12, 18, 25). Impaired performance at 24, 36, and 48 h. (7,22) and high mortality (18, 19,24) among During the initial 24-h period, means these animals illustrates the importance of for arterial partial pressure of oxygen elucidating mechanisms controlling the closure were 26 and 73 mm Hg for hypoxic and process with the ultimate goal of manipulating normoxic calves, respectively. In those these factors in a beneficial manner. fed colostrum at 0 and 12 h, hypoxia Oxygen consumption of the newborn inextended the period of Ig absorption cremes threefold above fetal levels in the first from 20 to 40.5 h. In calves fed whole 2 d (6), with much of this increase Occurring in milk or those that were fasted, no such the first 12 h (1). This is due in large part to effect was noted. These observations energy expenditures for maintenance of thersuggest that the effect of hypoxia on the mal neutrality (2,6,17). Activity of the gastrocessation of Ig absorption by the small intestinal tract also contributes to a significant intestine is mediated through a secondary extenc oxygen consumption rises 3.5-fold in and as yet undetermined mechanism. postnatal intestinal tissue at rest (10, 21) and (Key words: calves, immunoglobulins, increasing an additional 65 to 72% during hypoxia) digestion (4, 9). The primary objective of this experiment, Abbreviation key: p 0 2 = partial pressure of therefore, was to determine whether hypoxia oxygen, pC02 = partial pressure of carbon during the newborn period, i.e., maintaining dioxide. ) arterial partial pressure of oxygen ( ~ 0 2 near fetal levels, would delay the time of closure in INTRODUCTION the calf. Due to the absence of transplacental transfer MATERIALS AND METHODS of antibodies from maternal to fetal circulation, newborn calves are born essentially agamTwelve Holstein calves were assigned at birth to both a primary treatment (level of inspired oxygen) and secondary treatment (dietary regimen). Hypoxia was imposed Received October 15, 1990. within 2 min postpartum by providing calves a Accepted January 4, 1991. ABSTRACT
1991 J Dairy Sci 741952-1956
1953
1954
TYLER AND RAMSEY
1:l mixture of air and N2 via a face mask Fractional percentage of oxygen in the inspired gas mixture for hypoxic calves was 10.5%.A 30-L neoprene gas bag in the gas delivery system facilitated mixing of the gases as well as visualization of gas consumption. Flow rate was adjusted to the needs of individual calves. The duration of hypoxia was 24 h, at which time the use of a face mask was discontinued. Inspired air for nonnoxic calves, as well as hypoxic calves after 24 h, contained 21% oxygen. Oxygen content of inspired gases was determined twice daily using a Bacharach Fyrite oxygen analyzer (Bacharach Instruments, Pittsburgh, PA). A face mask was not used on normoxic calves during the initial 2 4 4 period. Dietary treatments superimposed upon the primary treatment during the initial 24-h pe riod were as follows: 1 kg of colostrum at 0 and 12 h, 1 kg of whole milk at 0 and 12 h, and fasting. All calves were fed 1 kg of colostrum at 24,36, and 48 h and2 kg of milk at 60 and 72 h. To ensure complete and uniform delivery of colostrum and milk, an esophageal feeder was utilized at all feedings. A pooled source of colostrum was used for all calves. Arterial blood was obtained two to three times daily by puncture from either the ventral coccygeal or carotid arteries, the choice depending on the physical position of the calf at the time of sampling. Samples were analyzed on an Instrumentation Laboratories System 1302 (Instrumentation Laboratories, Lexington, MA) blood gas system for determination of blood gas values. Values for arterial p@ during the initial 2 4 4 period are summarized in this paper. A detailed presentation of partial pressure of C02 ( p C 0 3 , and HCO; is made in a companion paper (27). Venous blood was sampled from the jugular vein at birth and at 6-h intervals through 48 h and again at 60 and 72 h. Samples at 0,12,24, 36, 48, 60, and 72 h were taken immediately prior to feeding. Plasma was separated by centrifugation at 1286 x g for 15 min and stored at -2O'C. Concentrations of IgG were quantitated via radial immunodiffusion with commercial gels (ICN Biomedicals, Inc., Costa Mesa, CA). Time of closure was estimated by calculating the join point as described by Hudson (13) and subsequently modified by Stott et al. (26). This procedure relies on the gradual decline in
m,
Journal of Dairy Science Vol. 74, No. 6, 1991
plasma IgG following cessation of transport, which reflects both catabolism of IgG and its transfer to extravascular pools (5). Thus, the resulting IgG concentration pattern in calves fed colostrum over the first 72 h describes a parabolic curve. By eliminating data points not occurring during the linear phase of absorption, the resulting observations can be fitted to two first-order regression lines. The intersection of these lines defines the join point, the estimate for time of closure. Sampling of blood, therefore, must be continued postclosure to satisfy requirements for both regression equations. All data were analyzed using the general linear models procedure of SAS (23). The statistical model included treatment, time, and calf effects. Significance of differences be tween means was determined by the method of least squares means using ANOVA. In all cases, probabilities greater than .05 were not considered significant, and results are reported accordingly. RESULTS AND DISCUSSION
The primary goal of the hypoxic treatment was to maintain arterial Po, near prenatal levels to prevent postnatal changes triggered by increased oxygen tension occuning at parturition. Published values for arterial Po, in the fetal calf vary from 19.5 (11) to 29.5 mm Hg (20), depending on sampling site and use of anaesthesia. Therefore, based on values obtained in this experiment (Po, = 26 nun Hg), our procedure for inducing hypoxia was successful. Values for normoxic calves during the
2000 T
,
0
6
1 2 18 2 4 30 36 42 48
0 normoxic
60
72
Age ( h )
Figure 1. Effect of hypoxia on absorption of IgG @ f SEW in newborn calves fed colostrum.
HYPOXIA AND CLOSURE IN NEWBORN C A L W
0normoxic EX3 hypoxic
Colostrum
Milk
Fasted
Figye 2. Effect of hypoxia and diet on peak plasma IgG (X f SEM) in newborn calves.
same period were substantially higher (PO, 73 mm Hg). Absorption of IgG in normoxic calves fed colostrum followed a typical absorptive pattern, relatively slow during the first 12 h and comparatively rapid after the second feeding a! 12 h (Figure 1). Due to the progressive nature of the closure process, only slight absorption occurzed between 18 and 24 h. Subsequent feedings of colostrum elicited no further increase in plasma IgG, indicating intestinal closure was complete prior to 24 h. In contrast to normoxic calves, absorption in hypoxic calves fed colostrum was slower during the first 18 h, with no apparent stimulation of absorptive function due to the second feeding (Figure 1). Rate of absorption increased dramatically after 18 h, and IgG levels did not diminish until between 42 and 48 h. The 48-h feeding of colostrum had no effect on plasma IgG. Absorptive capacity, as determined by the highest level of plasma IgG obtained, was unaffected by hypoxia. Extension of the absorptive period prior to closure without affecting capacity was accomplished by the diminished rate of absorption apparent during hypoxia, although high variation b e tween calves precludes any definite conclusions. The primary focus of this experiment was to determine the effects of hypoxia on time of closure in the newborn calf. When colostrum was fed at 0 and 12 h, time of closure was significantly delayed (P = .02) from 20 h in nonnoxic calves to 40.5 h in hypoxic calves. This developmental delay was not apparent in calves that were fasted or fed milk Minimal f:
1955
levels of IgG attained by calves that were fasted or fed milk relative to those fed colostnun suggest that closure was virtually complete by 24 h in both groups (Figure 2). The reasons for differences between dietary regimens are not readily apparent, but they suggest that the change in oxygen tension at biah is not the primary mediator of closure. There may be other mechanisms independent of changes in oxygen tension involved in the timing of closure in the calf. REFERENCES 1 Acheson, G. H., G. S. Daws, and J. C. Moa. 1957. Oxygen consumption and the arterial oxygen saturation in foetal and new-born lambs. J. PhysioL 135:623. 2Alexander, G. 1975. Body temperature control in maumahn young. Br. Med. Bull. 31:62. 3 A . s c b a f f ~ g , R., S. Bartlett, S. K. Kon, S. Y. Thompson, D. M. Walker,C. Briggs, E. Cotchin, and R b e l l . 1W9.Ibe nutritive significance of coloshum for the calf. Page 90 in Roc. 12th Int D airy congr. slockholm, Sweden. 4Brodie. T. G., W. C. Cullis, and W. D. Halliiurton. 1910. The gaseous metabolism of the small intestine. part II. Ibe gaseous exchanges during the absorption of Witte's peptone. J. Physiol. a . 1 7 3 . SBush,L. J.,M. A.Agailera, G. D.Adams,andE. W. Jonw. 1971. Absorption of colostal immmoglobulins by newborn dairy calves. J. Dairy Sci. 54:1547. 6Daws. G. S., and I. C. Moa. 1959. The increase in oxygen consumption of the lamb after birth. J. Physiol. 146:295. 7DeNiSe, S. K., J. D. ROb&OJl,G. H. Stott, and D. V. Amstrong. 1989. Effects of passive immunity on subsequent production in dairy heifers. I. Dairy Sci 72552. 8 -le, I. P. 1935. Influence of the ingestion of colostrum on the proteins of the blood sera of young foals, kids, lambs, and pigs. J. Agric. Res. 51:479. 9Edelstone. D. I., and I. R. Holpnan. 1981. Oxygen consumption by the gastrointestinal tract and liver in conscious newborn lambs. Am. J. Physiol. 2ru)..G297. l o E d e m , D. I., and I. R. Holzmaa 1981. Gastrointestinal tract 0, uptake and regional blood flows dnring digestion in conscious newborn lambs. Am. J. Physiol. 241:G289. 11Eigcmnann. V.UJB., E. Gruner& and U. Koppe. 1981. Znr spatasphyxie des kalbes. Bal. Muench. T i . w w a l l r . 94249. 12Gay, C. C., T. C. MCGujre, and S. M. Parish. 1983. Seasonal variation in passive transfer of imamnoglob ulin GI to newborn calves. J. Am. Vet. Med. Assoc. 183:566. 13 Hudson, D. J. 1966. Fitting segmented m e s whose pin points have to be estimated. J. Am. Stat. Assoc. 61:1097. 14 Jeffcott, L. B. 1974. Studies on passive immunity in the foal. II. he a m t i o n of '25I-la~edWP (polyvinyl pyrrolidonc) by the nconatal intestine. J. Comp. Pathol. W279. 15 Krose, V. 1970. Absorption of imtnunoglobuljn from
Jomnal of Dairy Science Vol. 74, No. 6, 1991
1956
TYLER AND RAMSEY
colostrum in newborn calves. Anim. Rod. 12:627. 16 M . 'I,M.J.G.S. 1971. Serum immunoglobulinsin newborn d v e s before and after colosmun feeding. Can. J. Comp. Med. 35269. 17Monnt, L. E. 1958. The oxygen consumption of the new-born pig in relation to enviroanental temperahue. J. Physiol. 142:37P. 18 Naylor, J. M.1979. Coloslral immunity in the calf and the foal. Vet. Clin. N.Am. Large Anim. Ract. 1:331. 19 Nocek, J. E., D. G. Braund, and R. G. Warner. 1984. Influence of neonatal colostrum admiuismtion, immunoglobdin, and continued feeding of colostram on calf gain, health, and semm protein. J. Dairy Sci. 6 7 319. 20Reeves, J. T., P. S. Daoud, and M. Gentry. 1972. Growth of the fetal calf and its arterial pressure, blood gases. and hematologic data. J. Awl. Physiol. 32240. 21Reeves, 1. T., and J. E. Leathers. 1964. Circalatory changes following birth of the calf and the effect of
Journal of Dairy Science Vol. 74. No. 6. 1991
hypoxia. Circ. Res. 15:343. 22Robison, J. D.. G. H. Stott, and S. K. DeNise. 1988. Effects of passive immunity on growth and survival in the dairy h e i f e r . J. Dairy Sci. 71:1283. 23SASQDUser's Guide: Statistics, Version 5 Edition. 1985. SAS Inst., Inc., Cary, NC. 24Smith, E. L., and A. Holm. 1948. The transfer of immunity to the new-born calf from colostrum. J. Biol. Chcm. 175349. UStaley, T. E., E. W. Jones, and L. J. Bush. 1971. Maternal transport of immunoglobulins to the calf. I. Dairy Sci. W1323. 26Stott, G. H., D. B. Marx, B. E. Menefee, and G. T. Nightengale. 1979. Colostral immunoglobulintransfer in cahres. 1. Period of absorption. J. Dairy Sci. 6 2 1632. 27Tyler, H. D., and H. A. Ramsey. 1991. Hypoxia in neonatal calves: effect on selected metabolic parameters. I. Dairy Sci. 741957.
