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Influence of Added Sodium Chloride in Grain Ration on the Freezing Point of Milk
Influence of Added Sodium Chloride in Grain Ration on the Freezing Point of Milk B. J. DEMOTT, S. A. HINTON, E. W. SWANSON, and J. T. MILES
Dairy Department, University of Tennessee, Knoxville Abstract
The effect of feeding grain mixtures containing 0, 1, 2, and 4% added sodium chloride on the freezing point of milk was determined by the use of eight Holstein cows in a modified Latin-square design. Feeding periods were two weeks on each mixture. Average freezing points were --0.548, --0.551, --0.552, and --0.553 C, respectively, when the grain contained 0, 1, 2, and 4% sodium chloride. Concentration of chloride in blood or miik did not change when salt intake was changed. Milk from three cows froze at average temperatures of --0.545, --0.550, and --0.553 and had total concentrations of sodium, potassium, calcium, magnesium, and chloride ions of 162.3, 138.7, and 129.3 mmoles per liter, respectively. Total concentrations of the five elements in milk were more closely correlated with sodium and chloride than with potassium, calcium, or magnesium; but among cows total concentration was not significantly correlated with freezing point. Alteration of mineral composition of milk by changes in dietary intake of minerals has been demonstrated primarily with minor elements (1), but the sodium and chloride content of milk appear to be unaltered by changes in the sodium chloride intake (8). Chloride content of blood has been altered, however, by altering intake of sodium chloride (5, 6, 8). Though somewhat conflicting data were obtained, a survey of production practices in West Tennessee indicated that salt intake might have a bearing upon freezing point depression of milk (3). The water intake pattern has been shown to affect freezing point of milk (12). The objectives of our investigation were to examine relationships between freezing point of milk and chloride, sodium, potassium, calcium, and magnesium concentrations which might be influenced by salt intake, amount of nfilk produced, water intake, and atmospheric temperature. Experimental Procedure
groups, each group containing one cow in early lactation and one in late lactation. Groups were assigned at random to a 4 X 4 Latin-square with an extra period to measure the carry-over effect (4). The groups were fed in rotation grain rations containing 0, l , 2, or 4% added sodium chloride for 2-week periods, t t a y , grain, and silage consumptions were determined each day. Daily water consumption was measured by a water meter installed on tlle drinking cup for each cow. H a y and silage were fed ad ]ibitum. Grain was fed to each cow at the rate of 1 kg grain for each 2 kg of 4% fat-corrected-milk produced over 4.5 kg per day at the beginning of the trial, and the daily ration of grain for each cow was kept constant for ten weeks during the experiment. Barn temperatures were taken on a centrally located recording thermometer, and mean daily temperatures were calculated by averaging temperatures from two-hour intervals. On the 10th, l l t h , and 12th day of each treatment period the rectal temperature of each cow was obtained and a sample of blood was drawn from her jugular vein. Body weights were determined on the 11th and 12th days of each test period. The freezing point of milk from each milking o~ each cow was determined by use of a thermistor-type cryoscope. Chloride in milk was determined by direct titration with AgNO~ (7). Chloride of blood plasma was determined by the method of Van Slyke and Hiller (11), and the plasma freezing point was determined as with milk. Analysis of variance was conducted by the method of Lucas (4). The significance of the correlation coefficients was determined by Snedecor's method (9). Three cows were chosen whose milk represented a low (0.545), high (0.553), and intermediate (0.550) average freezing point depression for the entire J:0-week period. Eight samples of milk not exceeding a freezing point of ±0.006 from the average were selected from each cow from each of the preliminary and five experimental periods for determining sodium, potassium, calcium, and magnesium by atomic adsorption or flame emission speetrophotometry.
Eight Holstein cows were divided into four
Results and Discussion All cows remained in apparent good health
Received for publication March 29, 1968.
during the experiment. 1363
Their average rectal
1364
DEN[OTT, H I N T O N , SWANSON, AND ~ I L E S
temperature was 38.5 C, with no significant difference (P > 0.05) among cows, periods, or levels of salt feeding. The average body weight, 619 kg, did not change significantly with periods, or level of salt feeding. Milk production declined gradually from an average of 20.8 kg per day during the first period to 18.9 during the fifth period. No change in milk production was attributed to level of salt in the feed (Table 1). Salt concentration in grain had a significant effect (P < 0.05) upon freezing point of milk, but n o significant carry-over effect of one treatment into the following treatment period was noted on freezing point of milk or blood. The correlation coefficient, r, between the average freezing point depression of milk for each cow and the actual salt intake for a two-week period was 0.45, which is significantly different (P < 0.01)from a zero effect. On the average, each additional 100 g salt fed per day, resulted in 0.001 C lower freezing point. Differences in freezing points between milk from various cows and between the two-week periods also were apparent (P < 0.01). The blood freezing point changed only with the change from zero to the 4% level of salt feeding. The concentration of chloride in blood and milk did not change when the salt intake was changed. Mean daily barn temperatures ranged from 1.5 to 18.4 C, with an over-all average of 9.3 C. Correlations between the 70 mean daily barn temperatures and average freezing point depressions of A~ and P~[ milk samples, or freezing point depression of blood on the same day were not significant. Correlation coeffieint of chloride concentration in milk and average barn temperature on the same day was --0.3 (P <
0.05). I n the temperature range experienced, each one degree C increase in barn temperature was accompanied by a decrease in milk chloride concentration of about 0.003%. Average barn temperature and fluid water consumption was significantly correlated, r ---- 0.8 (P < 0.01) ; with each one degree increase in temperature, water consumption increased about 0.9 liter per cow per day. The correlation coefficient of chloride concentration in blood and evening milk obtained the same days was not significant. As level of salt in the grain was increased, dry matter consumed was decreased, as reported earlier f o r Hereford cattle (13). As level of salt was increased water intake increased. The water ratio (last line Table 1) was greater at high salt intake levels, and was comparable to those found by Atkeson and Warren (2) for high producing cows. Milk from individual cows representing low, medium, and high freezing point depressions during the entire 10-week period was analyzed for mineral components (Table 2). Concentrations of minerals varied widely among cows. Total concentration of the five components varied inversely with freezing point depression. Concentration of sodium and chloride had the greatest effect upon total concentration of the five elements, but the correlation coefficient between concentration of any one element and freezing point depression varied in the three cows' milks. Sodium concentration of Cow 198 was abnormally high. An average of six samples of this cow's milk from the following lactation contained 34.9 mmoles sodium, 38.8 potassium, 29.0 calcium, and 5.9 mmoles magnesium per
TABLE 1. Influence of added sodinm chloride to the grain mixture upon several factors possibly related to freezing point of milk. Per cent NaC1 added to grain 0 Salt consumed (g/cow/day) Blood freezing point (--C)* Blood chloride (%)* Milk freezing point (--C)* Milk chloride (%) ~ Milk yield (kg/cow/day) ~ Fluid water consumed (1/cow/day) ~ Total water consumed (1/cow/day)* Dry matter intake (kg/cow/day)* Kg water consumed -- kg water in milk* kg dry matter intake Kg water consumed -- kg water in milk X 100"
1.3 0.555 ~
1
2
4
0.548 a 0.127 h 19.71 61.3 J 72.81 16.3 ~
70.0 0.557 ~b 0.364 ~ 0.5515 0.128 ~' 20.11 61.3 j 76.2 m 16.3~
149.6 0.556 ab 0.357 ° 0.5525 0.128 h 19.9 ~ 64.7k 76.3 ~ 16.0"0
189.0 0.559b 0.355 c 0.553 g 0.128h 19.8 t 66.3k 78.3 ~ 15.6 °
3.50p
3.66 q
3.78 q~
3.93 ~
9.12"
9.54 t
9.63 t"
9.95u
0.358 c
kg body wt Mean adjusted to show treatment effect only (Lucas, reference 4). a Yalues designated by the same letter are not statistically different (P > 0.05), as measured by Duncart's multiple range test (10). J'. DAIRY SOIENCE VO'L. 51, NO. 9
1365
~IILK FI~EEZING POINT
TABLE 2. Concentration in milk of certain ions, correlation between indlviduM and total ion concentrations, and correlation between freezing point depression and ion concentrations. Na Cow 198 (mean freezing point --0.545 C) Concentration (mmoles/1) Total Freezing point depression Cow 214 (mean freezing point --0.550 C) Concentration (mmoles/1) Total Freezing point depression Cow 293 (mean freezing point --0.553 C) Concentration (mmoles/1) Total Freezing point depression
I~2
Ca
Mg
C1
Total
r r
46.0 +0.95"* +0.34"*
32.1 --0.73"* --0.35"*
26.2 +0.13 --0.08
5.7 +0.11 --0.05
53.0 +0.78"* +0.37"
162.3" ........ +0.03
r r
30.0 +0.94"* +0.18
33.8 --0.65"* --0.01
29.5 --0.07 --0.04
5.2 --0.52"* --0.03
40.6 +0.92"* +0.13
138.7" ........ +0.13
r r
21.6 +0.68"* +0.08
37.8 +0.63"* +0.47"*
27.9 +0.01 --0.02
5.0 +0.57"* +0.21
36.9 +0.88"* +0.14
129.3" ........ +0.12
Due to rounding errors, total will not equal sum of components. * Significantly different from a zero effect (P < 0.05). ** Signifi.cantly different from a zero effect ( P < 0.01). liter, values t h a t are n e a r e r to those expected in n o r m a l milk. The influence o f salt c o n c e n t r a t i o n in the g r a i n m i x t u r e u p o n the sodium, potassium, calcium, magnesium, and chloride concentrations in milks f r o m t h r e e individual cows was not consistent between animals, a n d the relationship was not progressive.
References (1) Archibald, J. G. 1958. Trace elements in milk: A r e v l e w - - P a r t I. Dairy Sci. Abstr., 20: 712. P a r t II. Dairy Set., Abstr., 20: 800. (2) Atkeson, F. W., and T. R. Warren. 1934. The influence of type of ration and plane of production on water eonsmnption of dairy cows. J. Dairy Sei., 17:265. (3) Demott, B. J. 1966. The freezing point of milk produced in four markets in Tennessee. J. Milk and Pood Teehnol., 29: 319. (4) Lucas, It. L. 1957. Extra-period Latinsquare change-over design. J. Dairy Set., 40 : 225. (5) Pfeffer, E., J. Bertzbaeh, B. Helfferieh, and W. Lenkeit. 1965. The effect of feeding high levels of salt on the metabolisms of a dairy cow. I. Changes in the amount of chloride in the blood and excreted when the salt supplement is gradually increased. Z. Tierphysiol. Tierernahr. Futtermittelk. 20: (5) 305. Dairy Sci. Abstr., 28: 393. 1966.
(6) Pfeffer, E., B. IIe]fferieh, J. Bertzbaeh, I:[. IIerrmann, and W. Lenkeit. 1965. The effect of feeding high levels of salt on the metabolisms of a dairy cow. II. Changes in the excretion of chloride and the chloride content of blood following the sudden withdrawal of a large salt supplement. Z. Tierphysiol. Tierernahr. Futtermittelk. 20: 312.
Dairy Set., Abstr. 28" 394. 1966. (7) Sharp, P. F., and E. B. Struble. 1935. Period of lactation and the direct tltratable chloride value of milk. J. Dairy Sci., 18: 527. (8) Smith, S. E., and P. D. Aines. 1959. Salt requirements of dairy cows. Cornell Agr. Exp. Sta., Bull. 938. (9) Snedecor, G. W. 1956. Statistical methods. The Iowa State College Press. Ames, Iowa. (10) Steel, ]K G. D., and J. It. Torrie. 1960. Principles and Procedures of Statistics. McGraw-Hill Book Co., Inc., New York. (11) Van Slyke, D., and A. Hiller. 1947. Application of Sendroy's iodonletrie chloride titration to protein-containing fluids. J. Biol. Chem., 167: 107. (12) Wheelock, J. V., J. A. F. Rook, and F. IT. Dodd. 1965. The relationship in the cow between osmotle pressure of milk and blood. J. Dairy /~es., 32: 79. (13) Winchester, C. F., and M. J. !~orris. 1956. Water intake rates of cattle. J. Anim. Sci., 15 : 722.
J. DAIRY SeIENe~ ~/0L. 51, NO. 9
Dairy Department, University of Tennessee, Knoxville Abstract
The effect of feeding grain mixtures containing 0, 1, 2, and 4% added sodium chloride on the freezing point of milk was determined by the use of eight Holstein cows in a modified Latin-square design. Feeding periods were two weeks on each mixture. Average freezing points were --0.548, --0.551, --0.552, and --0.553 C, respectively, when the grain contained 0, 1, 2, and 4% sodium chloride. Concentration of chloride in blood or miik did not change when salt intake was changed. Milk from three cows froze at average temperatures of --0.545, --0.550, and --0.553 and had total concentrations of sodium, potassium, calcium, magnesium, and chloride ions of 162.3, 138.7, and 129.3 mmoles per liter, respectively. Total concentrations of the five elements in milk were more closely correlated with sodium and chloride than with potassium, calcium, or magnesium; but among cows total concentration was not significantly correlated with freezing point. Alteration of mineral composition of milk by changes in dietary intake of minerals has been demonstrated primarily with minor elements (1), but the sodium and chloride content of milk appear to be unaltered by changes in the sodium chloride intake (8). Chloride content of blood has been altered, however, by altering intake of sodium chloride (5, 6, 8). Though somewhat conflicting data were obtained, a survey of production practices in West Tennessee indicated that salt intake might have a bearing upon freezing point depression of milk (3). The water intake pattern has been shown to affect freezing point of milk (12). The objectives of our investigation were to examine relationships between freezing point of milk and chloride, sodium, potassium, calcium, and magnesium concentrations which might be influenced by salt intake, amount of nfilk produced, water intake, and atmospheric temperature. Experimental Procedure
groups, each group containing one cow in early lactation and one in late lactation. Groups were assigned at random to a 4 X 4 Latin-square with an extra period to measure the carry-over effect (4). The groups were fed in rotation grain rations containing 0, l , 2, or 4% added sodium chloride for 2-week periods, t t a y , grain, and silage consumptions were determined each day. Daily water consumption was measured by a water meter installed on tlle drinking cup for each cow. H a y and silage were fed ad ]ibitum. Grain was fed to each cow at the rate of 1 kg grain for each 2 kg of 4% fat-corrected-milk produced over 4.5 kg per day at the beginning of the trial, and the daily ration of grain for each cow was kept constant for ten weeks during the experiment. Barn temperatures were taken on a centrally located recording thermometer, and mean daily temperatures were calculated by averaging temperatures from two-hour intervals. On the 10th, l l t h , and 12th day of each treatment period the rectal temperature of each cow was obtained and a sample of blood was drawn from her jugular vein. Body weights were determined on the 11th and 12th days of each test period. The freezing point of milk from each milking o~ each cow was determined by use of a thermistor-type cryoscope. Chloride in milk was determined by direct titration with AgNO~ (7). Chloride of blood plasma was determined by the method of Van Slyke and Hiller (11), and the plasma freezing point was determined as with milk. Analysis of variance was conducted by the method of Lucas (4). The significance of the correlation coefficients was determined by Snedecor's method (9). Three cows were chosen whose milk represented a low (0.545), high (0.553), and intermediate (0.550) average freezing point depression for the entire J:0-week period. Eight samples of milk not exceeding a freezing point of ±0.006 from the average were selected from each cow from each of the preliminary and five experimental periods for determining sodium, potassium, calcium, and magnesium by atomic adsorption or flame emission speetrophotometry.
Eight Holstein cows were divided into four
Results and Discussion All cows remained in apparent good health
Received for publication March 29, 1968.
during the experiment. 1363
Their average rectal
1364
DEN[OTT, H I N T O N , SWANSON, AND ~ I L E S
temperature was 38.5 C, with no significant difference (P > 0.05) among cows, periods, or levels of salt feeding. The average body weight, 619 kg, did not change significantly with periods, or level of salt feeding. Milk production declined gradually from an average of 20.8 kg per day during the first period to 18.9 during the fifth period. No change in milk production was attributed to level of salt in the feed (Table 1). Salt concentration in grain had a significant effect (P < 0.05) upon freezing point of milk, but n o significant carry-over effect of one treatment into the following treatment period was noted on freezing point of milk or blood. The correlation coefficient, r, between the average freezing point depression of milk for each cow and the actual salt intake for a two-week period was 0.45, which is significantly different (P < 0.01)from a zero effect. On the average, each additional 100 g salt fed per day, resulted in 0.001 C lower freezing point. Differences in freezing points between milk from various cows and between the two-week periods also were apparent (P < 0.01). The blood freezing point changed only with the change from zero to the 4% level of salt feeding. The concentration of chloride in blood and milk did not change when the salt intake was changed. Mean daily barn temperatures ranged from 1.5 to 18.4 C, with an over-all average of 9.3 C. Correlations between the 70 mean daily barn temperatures and average freezing point depressions of A~ and P~[ milk samples, or freezing point depression of blood on the same day were not significant. Correlation coeffieint of chloride concentration in milk and average barn temperature on the same day was --0.3 (P <
0.05). I n the temperature range experienced, each one degree C increase in barn temperature was accompanied by a decrease in milk chloride concentration of about 0.003%. Average barn temperature and fluid water consumption was significantly correlated, r ---- 0.8 (P < 0.01) ; with each one degree increase in temperature, water consumption increased about 0.9 liter per cow per day. The correlation coefficient of chloride concentration in blood and evening milk obtained the same days was not significant. As level of salt in the grain was increased, dry matter consumed was decreased, as reported earlier f o r Hereford cattle (13). As level of salt was increased water intake increased. The water ratio (last line Table 1) was greater at high salt intake levels, and was comparable to those found by Atkeson and Warren (2) for high producing cows. Milk from individual cows representing low, medium, and high freezing point depressions during the entire 10-week period was analyzed for mineral components (Table 2). Concentrations of minerals varied widely among cows. Total concentration of the five components varied inversely with freezing point depression. Concentration of sodium and chloride had the greatest effect upon total concentration of the five elements, but the correlation coefficient between concentration of any one element and freezing point depression varied in the three cows' milks. Sodium concentration of Cow 198 was abnormally high. An average of six samples of this cow's milk from the following lactation contained 34.9 mmoles sodium, 38.8 potassium, 29.0 calcium, and 5.9 mmoles magnesium per
TABLE 1. Influence of added sodinm chloride to the grain mixture upon several factors possibly related to freezing point of milk. Per cent NaC1 added to grain 0 Salt consumed (g/cow/day) Blood freezing point (--C)* Blood chloride (%)* Milk freezing point (--C)* Milk chloride (%) ~ Milk yield (kg/cow/day) ~ Fluid water consumed (1/cow/day) ~ Total water consumed (1/cow/day)* Dry matter intake (kg/cow/day)* Kg water consumed -- kg water in milk* kg dry matter intake Kg water consumed -- kg water in milk X 100"
1.3 0.555 ~
1
2
4
0.548 a 0.127 h 19.71 61.3 J 72.81 16.3 ~
70.0 0.557 ~b 0.364 ~ 0.5515 0.128 ~' 20.11 61.3 j 76.2 m 16.3~
149.6 0.556 ab 0.357 ° 0.5525 0.128 h 19.9 ~ 64.7k 76.3 ~ 16.0"0
189.0 0.559b 0.355 c 0.553 g 0.128h 19.8 t 66.3k 78.3 ~ 15.6 °
3.50p
3.66 q
3.78 q~
3.93 ~
9.12"
9.54 t
9.63 t"
9.95u
0.358 c
kg body wt Mean adjusted to show treatment effect only (Lucas, reference 4). a Yalues designated by the same letter are not statistically different (P > 0.05), as measured by Duncart's multiple range test (10). J'. DAIRY SOIENCE VO'L. 51, NO. 9
1365
~IILK FI~EEZING POINT
TABLE 2. Concentration in milk of certain ions, correlation between indlviduM and total ion concentrations, and correlation between freezing point depression and ion concentrations. Na Cow 198 (mean freezing point --0.545 C) Concentration (mmoles/1) Total Freezing point depression Cow 214 (mean freezing point --0.550 C) Concentration (mmoles/1) Total Freezing point depression Cow 293 (mean freezing point --0.553 C) Concentration (mmoles/1) Total Freezing point depression
I~2
Ca
Mg
C1
Total
r r
46.0 +0.95"* +0.34"*
32.1 --0.73"* --0.35"*
26.2 +0.13 --0.08
5.7 +0.11 --0.05
53.0 +0.78"* +0.37"
162.3" ........ +0.03
r r
30.0 +0.94"* +0.18
33.8 --0.65"* --0.01
29.5 --0.07 --0.04
5.2 --0.52"* --0.03
40.6 +0.92"* +0.13
138.7" ........ +0.13
r r
21.6 +0.68"* +0.08
37.8 +0.63"* +0.47"*
27.9 +0.01 --0.02
5.0 +0.57"* +0.21
36.9 +0.88"* +0.14
129.3" ........ +0.12
Due to rounding errors, total will not equal sum of components. * Significantly different from a zero effect (P < 0.05). ** Signifi.cantly different from a zero effect ( P < 0.01). liter, values t h a t are n e a r e r to those expected in n o r m a l milk. The influence o f salt c o n c e n t r a t i o n in the g r a i n m i x t u r e u p o n the sodium, potassium, calcium, magnesium, and chloride concentrations in milks f r o m t h r e e individual cows was not consistent between animals, a n d the relationship was not progressive.
References (1) Archibald, J. G. 1958. Trace elements in milk: A r e v l e w - - P a r t I. Dairy Sci. Abstr., 20: 712. P a r t II. Dairy Set., Abstr., 20: 800. (2) Atkeson, F. W., and T. R. Warren. 1934. The influence of type of ration and plane of production on water eonsmnption of dairy cows. J. Dairy Sei., 17:265. (3) Demott, B. J. 1966. The freezing point of milk produced in four markets in Tennessee. J. Milk and Pood Teehnol., 29: 319. (4) Lucas, It. L. 1957. Extra-period Latinsquare change-over design. J. Dairy Set., 40 : 225. (5) Pfeffer, E., J. Bertzbaeh, B. Helfferieh, and W. Lenkeit. 1965. The effect of feeding high levels of salt on the metabolisms of a dairy cow. I. Changes in the amount of chloride in the blood and excreted when the salt supplement is gradually increased. Z. Tierphysiol. Tierernahr. Futtermittelk. 20: (5) 305. Dairy Sci. Abstr., 28: 393. 1966.
(6) Pfeffer, E., B. IIe]fferieh, J. Bertzbaeh, I:[. IIerrmann, and W. Lenkeit. 1965. The effect of feeding high levels of salt on the metabolisms of a dairy cow. II. Changes in the excretion of chloride and the chloride content of blood following the sudden withdrawal of a large salt supplement. Z. Tierphysiol. Tierernahr. Futtermittelk. 20: 312.
Dairy Set., Abstr. 28" 394. 1966. (7) Sharp, P. F., and E. B. Struble. 1935. Period of lactation and the direct tltratable chloride value of milk. J. Dairy Sci., 18: 527. (8) Smith, S. E., and P. D. Aines. 1959. Salt requirements of dairy cows. Cornell Agr. Exp. Sta., Bull. 938. (9) Snedecor, G. W. 1956. Statistical methods. The Iowa State College Press. Ames, Iowa. (10) Steel, ]K G. D., and J. It. Torrie. 1960. Principles and Procedures of Statistics. McGraw-Hill Book Co., Inc., New York. (11) Van Slyke, D., and A. Hiller. 1947. Application of Sendroy's iodonletrie chloride titration to protein-containing fluids. J. Biol. Chem., 167: 107. (12) Wheelock, J. V., J. A. F. Rook, and F. IT. Dodd. 1965. The relationship in the cow between osmotle pressure of milk and blood. J. Dairy /~es., 32: 79. (13) Winchester, C. F., and M. J. !~orris. 1956. Water intake rates of cattle. J. Anim. Sci., 15 : 722.
J. DAIRY SeIENe~ ~/0L. 51, NO. 9