BACKGROUND
colostrum is vital food for the newborn of all mammals within the first 5- <dig> days after parturition.
colostrum contains various nutrients  as well as many biologically active substances such as immunoglobulins, antimicrobial factors, growth factors and others  <cit> .
the quality of colostrum has a strong relationship with colostral immunoglobulin level .
the most abundant cil in the ruminants' colostrum is the igg, followed by igm and iga  <cit> .
calves are born without blood immunoglobulins , so they depend on their mother's colostrum in order to obtain immunity  <cit> .
transference of passive immunity throughout the colostrum is essential for the calf's health and survival during its first days of life  <cit> .
because colostrum is very important to the newborn, producers must often make provision to have a source of colostrum available if and when the dam does not provide enough high quality colostrum for the calf.
in addition, numerous studies suggest that oral administration of bovine colostrum preparations may contribute to human health care both as part of a health promoting diet and as an alternative or supplement to the medical treatment of specified human diseases  <cit> .
the colostrum composition and its quality are influenced by a variety of factors, including maternal age, parity, breed, nutritional status, season, premature parturition, premature lactation, colostral handling factors , induction of parturition and health status  <cit> .
during transition from colostrum to normal milk, gradual or sometimes sudden changes may occur in composition and properties  <cit> .
knowing the composition and physical properties of colostrum and post-colostrum secretions will help establish when such milk is suitable for processing and determine the best use for that milk  <cit> .
several studies have evaluated the changes in the chemical composition of cow colostrum after parturition, but there is not available information about buffalo colostrum which represents approximately 49%  <cit>  of lactating ruminants in egypt.
so, the aim of this study was to follow the changes in colostrum composition of egyptian buffaloes and holstein cows after parturition.
methods
animals and management
egyptian buffaloes and holstein cows were selected from open nucleus herd from cattle information system of egypt  and technology centre of agricultural production, faculty of agriculture, cairo university.
all animals were in the second lactation and their milk production level in the first lactation was  <dig> kg/parity for buffalo and  <dig> kg/parity for cow.
they fed clover misqawi, rice straw and concentrate , and housed in free stalls.
this study was approved by the university of cairo animal care committee.
collection of colostrum samples
colostrum samples from  <dig> buffaloes and  <dig> cows were collected during the winter seasons of  <dig>   <dig> and 2011; totalling  <dig> buffaloes and  <dig> cows.
all samples were analyzed at caving,  <dig>   <dig>   <dig>   <dig>   <dig>   <dig>   <dig> h and after  <dig> days of parturition.
methods of analysis
samples were analyzed for total solids, total protein, whey proteins, lactose and ash contents according to  <cit> .
fat was determined by gerber method according to  <cit> .
calcium , mg, na, k, fe, cu, zn, pb were estimated by inductively coupled plasma atomic emission spectrometry  using icap  <dig> series; thermo scientific.
phosphorus was determined colorimetrically according to  <cit> .
vitamin a was determined according to  <cit> .
vitamin e was colorimetrically estimated by the method of  <cit> .
a double antibody radioimmunoassay was used to quantify insulin like-growth factor- <dig>  according to  <cit> .
biosource igf-1-ria-ct kit  was used.
the immunoglobulin g  and immunoglobulin m  contents were quantified using single radial immuno diffusion technique  as described by fahey and mackelvey  <cit> .
srid plates containing antibodies to igg and igm  were used.
lactoferrin content was determined using enzyme-linked immunosorbent assay  according to  <cit> .
elisa plates containing antibodies to bovine lactoferrin  were used.
statistical analysis
the following two-way analysis model was used to study the effect of breed and time after parturition on the studied traits:
yijk=μ+bi+tj+eijk
where:
yijk: the observations,   μ: over all mean,
bi: the effect of ith breed {i =  <dig> ,  <dig> },
tj: the effect of jth time after parturition; where j = time of sampling , and
eijk: the random error.
the least significant difference  test was calculated to compare the significant differences between the mean of different treatments  <cit> .
all statistical calculations were performed using mstat-c  <cit> .
results were considered statistically at a significance level of p ≤  <dig> .
RESULTS
colostrum gross chemical composition
changes in total protein, whey proteins, fat, lactose, ash and total solids concentration of buffalo and cow colostrum in the first five days and after  <dig> days of parturition are presented in figure  <dig>  at calving, the total solids, total protein, whey proteins and fat concentrations of buffalo colostrum were  <dig> ,  <dig> ,  <dig>  and  <dig> % and in cow colostrum were  <dig> ,  <dig> ,  <dig>  and  <dig> %, respectively.
similar results were reported by kehoe et al.,  <cit> , mechor et al.,  <cit>  and wroński and sosnowska  <cit>  for cow colostrum and nawar  <cit>  for buffalo colostrum.
our results showed that total protein and whey proteins concentration did not differ significantly between buffalo and cow colostrum, while fat and total solids were significantly higher in buffalo colostrum.
as the transition period advanced, these components in both colostrums decreased gradually.
generally, on the fifth day of parturition, the composition of both colostrums approached to normal milk composition and was similar to that after  <dig> days of parturition.
at calving, lactose concentration of buffalo colostrum was significantly higher than in cow colostrum .
in this respect,  <cit>  found that buffalo colostrum contained  <dig> % lactose, while  <cit>  recorded  <dig> % for cow colostrum.
lactose concentration increased until the fifth day of parturition.
on the 14th day post-partum, lactose concentration of buffalo and cow milk was  <dig> % and  <dig> %, respectively which was similar to that of the normal milk .
as shown in figure  <dig>  the first buffalo and cow colostrum had ash percentages of  <dig> % and  <dig> %, respectively which was similar to that reported by qyeniyi and hunter  <cit>  and toshiyoshi et al.,  <cit>  for cow colostrum.
at  <dig> h post-partum, the ash concentration decreased significantly for buffalo  and cow  colostrum.
the ash concentration of both colostrums continued to decrease reaching a value of  <dig> %.
colostrum macro- and micro-elements
tables  <dig> and  <dig> present the changes in macro- and micro-elements concentration in buffalo and cow colostrum during the first five days and after  <dig> days of parturition.
at calving, cow colostrum had higher concentrations of mg, na, k and zn and lower concentration of p than buffalo colostrum.
however, there were no differences between both colostrums in ca, fe, cu and pb concentrations.
the macro- and micro-elements concentration decreased gradually toward normality after five days of parturition.
similar differences in respect to na during the experimental period  were reported by ontsouka et al.,  <cit>  for cow colostrum.
the opposite trend with regards to k was found by toshiyoshi et al.,  <cit>  for cow colostrum, while  <cit>  did not find remarkable change between the initial and final k concentration of cow colostrum.
means in the same column or row of each element with different superscript letters differ significantly
sd: standard deviation of the mean
means in the same column or row of each element with different superscript letters differ significantly
sd: standard deviation of the mean
colostrum vitamins
changes in vitamins a and e in buffalo and cow colostrum during the first five days and after  <dig> days of parturition are shown in table  <dig>  at calving, the concentration of vitamin a in buffalo colostrum was found to be approximately  <dig>  times lower than in cow colostrum.
as the post-partum time advanced, the concentration of vitamin a in both colostrums decreased to reach the values of  <dig>  and  <dig>  iu/ <dig> ml after  <dig> days in buffalo and cow colostrum, respectively.
as for cow colostrum,  <cit>  reported similar results.
means in the same column or row of each vitamin with different superscript letters differ significantly
sd: standard deviation of the mean
colostrum bioactive components
the results of igg, igm, igf- <dig> and lactoferrin of buffalo and cow colostrum are shown in figure  <dig>  at calving, there were no significant differences in igg and igm concentration between buffalo and cow colostrum.
the concentrations of igg and igm were  <dig>  and  <dig>  mg/ml in buffalo and  <dig>  and  <dig>  mg/ml in cow colostrum, respectively.
similar results were published by mechor et al.,  <cit>  for igg and quigley et al.,  <cit>  for igm in cow colostrum.
the concentrations of igg and igm decreased in both colostrums and reached to normal values after five days of parturition and it was observed a sharp decrease in igg compared to igm.
at calving, igf- <dig> concentration was significantly higher in buffalo colostrum  than that in cow colostrum .
the concentration of igf- <dig> in cow colostrum is in agreement with the results reported by elfstrand et al.,  <cit> .
the concentration of igf- <dig> in both colostrums reduced significantly by  <dig> % after  <dig> h of parturition; and by  <dig> % for buffalo and by  <dig> % for cow colostrum after five days post-partum .
at calving, lactoferrin concentration was significantly lower in buffalo colostrum than that in cow colostrum.
the concentration of lactoferrin in the first buffalo colostrum was  <dig>  mg/ml and decreased significantly to reach the normal value of  <dig>  mg/ml after  <dig> days of parturition.
on the other hand, the first cow colostrum contained  <dig>  mg/ml lactoferrin and decreased significantly to  <dig>  mg/ml after five days post-partum .
lactoferrin concentration of the first buffalo colostrum is lower than that reported by nawar  <cit>  and higher than that reported by mahran et al.,  <cit> .
CONCLUSIONS
at calving, the buffalo colostrum has higher concentrations of fat, ash, total solids, lactose, vitamin e, phosphorus and igf- <dig> and lower concentrations of mg, k, na, zn, vitamin a and lactoferrin than cow colostrum.
on the fifth day of parturition, buffalo colostrum has higher fat, total solids, ca, mg and vitamin e and lower na, p, cu, zn and vitamin a concentrations than cow colostrum.
the composition of both colostrums approaches to normal milk composition during the first five days after parturition.
authors' contributions
ama and fhra carried out the study design, participated in data organization, wrote and revised the manuscript; sme participated in data organization, wrote and revised the manuscript; hae carried out all the experiments, participated in data organization, wrote and revised the manuscript.
all authors read and approved the final manuscript.

 colostrum is vital food for the newborn of all mammals within the first 5- days after parturition. colostrum contains various nutrients as well as many biologically active substances such as immunoglobulins, antimicrobial factors, growth factors and others. the quality of colostrum has a strong relationship with colostral immunoglobulin level. the most abundant cil in the ruminants' colostrum is the igg, followed by igm and iga. calves are born without blood immunoglobulins, so they depend on their mother's colostrum in order to obtain immunity. transference of passive immunity throughout the colostrum is essential for the calf's health and survival during its first days of life. because colostrum is very important to the newborn, producers must often make provision to have a source of colostrum available if and when the dam does not provide enough high quality colostrum for the calf. in addition, numerous studies suggest that oral administration of bovine colostrum preparations may contribute to human health care both as part of a health promoting diet and as an alternative or supplement to the medical treatment of specified human diseases. the colostrum composition and its quality are influenced by a variety of factors, including maternal age, parity, breed, nutritional status, season, premature parturition, premature lactation, colostral handling factors, induction of parturition and health status. during transition from colostrum to normal milk, gradual or sometimes sudden changes may occur in composition and properties. knowing the composition and physical properties of colostrum and post-colostrum secretions will help establish when such milk is suitable for processing and determine the best use for that milk. several studies have evaluated the changes in the chemical composition of cow colostrum after parturition, but there is not available information about buffalo colostrum which represents approximately 49% of lactating ruminants in egypt. so, the aim of this study was to follow the changes in colostrum composition of egyptian buffaloes and holstein cows after parturition. methods animals and management egyptian buffaloes and holstein cows were selected from open nucleus herd from cattle information system of egypt and technology centre of agricultural production, faculty of agriculture, cairo university. all animals were in the second lactation and their milk production level in the first lactation was kg/parity for buffalo and kg/parity for cow. they fed clover misqawi, rice straw and concentrate, and housed in free stalls. this study was approved by the university of cairo animal care committee. collection of colostrum samples colostrum samples from buffaloes and cows were collected during the winter seasons of and 2011; totalling buffaloes and cows. all samples were analyzed at caving, h and after days of parturition. methods of analysis samples were analyzed for total solids, total protein, whey proteins, lactose and ash contents according to. fat was determined by gerber method according to. calcium, mg, na, k, fe, cu, zn, pb were estimated by inductively coupled plasma atomic emission spectrometry using icap series; thermo scientific. phosphorus was determined colorimetrically according to. vitamin a was determined according to. vitamin e was colorimetrically estimated by the method of. a double antibody radioimmunoassay was used to quantify insulin like-growth factor- according to. biosource igf-1-ria-ct kit was used. the immunoglobulin g and immunoglobulin m contents were quantified using single radial immuno diffusion technique as described by fahey and mackelvey. srid plates containing antibodies to igg and igm were used. lactoferrin content was determined using enzyme-linked immunosorbent assay according to. elisa plates containing antibodies to bovine lactoferrin were used. statistical analysis the following two-way analysis model was used to study the effect of breed and time after parturition on the studied traits: yijk=μ+bi+tj+eijk where: yijk: the observations,   μ: over all mean, bi: the effect of ith breed {i =, }, tj: the effect of jth time after parturition; where j = time of sampling, and eijk: the random error. the least significant difference test was calculated to compare the significant differences between the mean of different treatments. all statistical calculations were performed using mstat-c. results were considered statistically at a significance level of p ≤.  colostrum gross chemical composition changes in total protein, whey proteins, fat, lactose, ash and total solids concentration of buffalo and cow colostrum in the first five days and after days of parturition are presented in figure at calving, the total solids, total protein, whey proteins and fat concentrations of buffalo colostrum were,, and % and in cow colostrum were,, and %, respectively. similar results were reported by kehoe et al.,, mechor et al., and wroński and sosnowska for cow colostrum and nawar for buffalo colostrum. our results showed that total protein and whey proteins concentration did not differ significantly between buffalo and cow colostrum, while fat and total solids were significantly higher in buffalo colostrum. as the transition period advanced, these components in both colostrums decreased gradually. generally, on the fifth day of parturition, the composition of both colostrums approached to normal milk composition and was similar to that after days of parturition. at calving, lactose concentration of buffalo colostrum was significantly higher than in cow colostrum. in this respect, found that buffalo colostrum contained % lactose, while recorded % for cow colostrum. lactose concentration increased until the fifth day of parturition. on the 14th day post-partum, lactose concentration of buffalo and cow milk was % and %, respectively which was similar to that of the normal milk. as shown in figure the first buffalo and cow colostrum had ash percentages of % and %, respectively which was similar to that reported by qyeniyi and hunter and toshiyoshi et al., for cow colostrum. at h post-partum, the ash concentration decreased significantly for buffalo and cow colostrum. the ash concentration of both colostrums continued to decrease reaching a value of %. colostrum macro- and micro-elements tables and present the changes in macro- and micro-elements concentration in buffalo and cow colostrum during the first five days and after days of parturition. at calving, cow colostrum had higher concentrations of mg, na, k and zn and lower concentration of p than buffalo colostrum. however, there were no differences between both colostrums in ca, fe, cu and pb concentrations. the macro- and micro-elements concentration decreased gradually toward normality after five days of parturition. similar differences in respect to na during the experimental period were reported by ontsouka et al., for cow colostrum. the opposite trend with regards to k was found by toshiyoshi et al., for cow colostrum, while did not find remarkable change between the initial and final k concentration of cow colostrum. means in the same column or row of each element with different superscript letters differ significantly sd: standard deviation of the mean means in the same column or row of each element with different superscript letters differ significantly sd: standard deviation of the mean colostrum vitamins changes in vitamins a and e in buffalo and cow colostrum during the first five days and after days of parturition are shown in table at calving, the concentration of vitamin a in buffalo colostrum was found to be approximately times lower than in cow colostrum. as the post-partum time advanced, the concentration of vitamin a in both colostrums decreased to reach the values of and iu/ ml after days in buffalo and cow colostrum, respectively. as for cow colostrum, reported similar results. means in the same column or row of each vitamin with different superscript letters differ significantly sd: standard deviation of the mean colostrum bioactive components the results of igg, igm, igf- and lactoferrin of buffalo and cow colostrum are shown in figure at calving, there were no significant differences in igg and igm concentration between buffalo and cow colostrum. the concentrations of igg and igm were and mg/ml in buffalo and and mg/ml in cow colostrum, respectively. similar results were published by mechor et al., for igg and quigley et al., for igm in cow colostrum. the concentrations of igg and igm decreased in both colostrums and reached to normal values after five days of parturition and it was observed a sharp decrease in igg compared to igm. at calving, igf- concentration was significantly higher in buffalo colostrum than that in cow colostrum. the concentration of igf- in cow colostrum is in agreement with the results reported by elfstrand et al.,. the concentration of igf- in both colostrums reduced significantly by % after h of parturition; and by % for buffalo and by % for cow colostrum after five days post-partum. at calving, lactoferrin concentration was significantly lower in buffalo colostrum than that in cow colostrum. the concentration of lactoferrin in the first buffalo colostrum was mg/ml and decreased significantly to reach the normal value of mg/ml after days of parturition. on the other hand, the first cow colostrum contained mg/ml lactoferrin and decreased significantly to mg/ml after five days post-partum. lactoferrin concentration of the first buffalo colostrum is lower than that reported by nawar and higher than that reported by mahran et al.,.  at calving, the buffalo colostrum has higher concentrations of fat, ash, total solids, lactose, vitamin e, phosphorus and igf- and lower concentrations of mg, k, na, zn, vitamin a and lactoferrin than cow colostrum. on the fifth day of parturition, buffalo colostrum has higher fat, total solids, ca, mg and vitamin e and lower na, p, cu, zn and vitamin a concentrations than cow colostrum. the composition of both colostrums approaches to normal milk composition during the first five days after parturition. authors' contributions ama and fhra carried out the study design, participated in data organization, wrote and revised the manuscript; sme participated in data organization, wrote and revised the manuscript; hae carried out all the experiments, participated in data organization, wrote and revised the manuscript. all authors read and approved the final manuscript. 
total solids, total protein, whey proteins, fat, lactose and ash contents were determined. at calving, the total protein and whey proteins concentration did not differ between buffalo and cow colostrum, while total solids, fat, lactose and ash concentrations were higher in buffalo than in cow colostrum. on the fifth day post-partum, concentration of total protein, whey proteins, fat, ash and total solids decreased by,,, and % for buffalo and by,,, and % for cow colostrum. all components decreased gradually as the transition period advanced except lactose which conversely increased. buffalo colostrum had a higher concentration of vitamin e than cow colostrum during the experimental period. changes in colostrum composition of egyptian buffaloes and holstein cows collected at calving, h and after days of parturition were studied. there is a dramatic change in buffalo and cow colostrum composition from the first milking until the fifth day of parturition. there are differences between buffalo and cow colostrum composition during the five days after calving. the composition of both colostrums approaches to those of normal milk within five days after parturition. however, lactose concentration increased by % for buffalo and % for cow colostrum. at calving, the concentration of vitamin a in buffalo colostrum was found to be approximately times lower than in cow colostrum. the concentrations of igg, igm, igf- and lactoferrin decreased by,, and % for buffalo and,, and % for cow colostrum, respectively after five days of parturition.
 changes in colostrum composition of egyptian buffaloes and holstein cows collected at calving, h and after days of parturition were studied. total solids, total protein, whey proteins, fat, lactose and ash contents were determined. macro- and micro-elements, igg, igm, igf- lactoferrin and vitamins were also estimated.  at calving, the total protein and whey proteins concentration did not differ between buffalo and cow colostrum, while total solids, fat, lactose and ash concentrations were higher in buffalo than in cow colostrum. all components decreased gradually as the transition period advanced except lactose which conversely increased. on the fifth day post-partum, concentration of total protein, whey proteins, fat, ash and total solids decreased by,,, and % for buffalo and by,,, and % for cow colostrum. however, lactose concentration increased by % for buffalo and % for cow colostrum. the macro-and micro-elements concentration of both colostrums tended to decline slightly toward normality on the fifth day of parturition. buffalo colostrum had a higher concentration of vitamin e than cow colostrum during the experimental period. at calving, the concentration of vitamin a in buffalo colostrum was found to be approximately times lower than in cow colostrum. the concentrations of igg, igm, igf- and lactoferrin decreased by,, and % for buffalo and,, and % for cow colostrum, respectively after five days of parturition.  there is a dramatic change in buffalo and cow colostrum composition from the first milking until the fifth day of parturition. there are differences between buffalo and cow colostrum composition during the five days after calving. the composition of both colostrums approaches to those of normal milk within five days after parturition. 