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Major Minerals in Blood of West African Dwarf Goats During Lactation
M a j o r M i n e r a l s in B l o o d of West A f r i c a n D w a r f Goats D u r i n g L a c t a t i o n A. O.
AKINSOYINU
Department of Animal Science University of Ibadan
Ibadan, Nigeria ABSTRACT
Twenty
adult
West African
dwarf
(Fouta djallon) does about 2 yr old and weighing from 23 to 28 kg were kept for two 18-wk lactations. Blood samples were obtained once weekly from 2 to 18 wk of lactation except in the 1st wk after parturition when samples were every other day for chemical analysis. Blood serum from the 2nd to the 18th wk contained the following averages (mg/100 ml) with standard deviations: calcium 10.52, 1.47; phosphorus 7.43, 1.0; magnesium 2.99, .42; (meq/liter) sodium 140.10, 3.83; and potassium 4.99, .45. In blood during the 1st wk after parturition they were 8.46, .40; 6.05, .12; 3.74, .12; 147.72, .63; and 6.28, .25. Trends increased with advance in lactation except for magnesium and potassium, which decreased. INTRODUCTION
Studies on goats are receiving attention by scientists all over the world. This stems from the growing awareness of the need to accumulate information on goats, which have been neglected compared with sheep and carte (9). The paucity of information on performance and production by goats with special emphasis on tropical breeds has been highlighted (9). Attention also has been on characteristics and composition of goat milk and of West African dwarf (WAD) goats in particular (2, 3, 4). While there has been information on major and trace elements in milk of WAD goats (2, 4), little is on the concentration of these minerals in blood during lactation. Few experiments on Ca, P, and Mg in goat blood during lactation (13, 19) were on temperate breeds. Since mineral constituents in milk have been derived from blood
Received March 11, 1980. 1982 J Dairy Sci 65:874-877
(8, 16), such information will contribute to our basic knowledge on WAD goats as reported in this paper. MATERIALS AND METHODS Animals and Their Management
Experiments used 20 adult does approximately 2 yr old, weighing 23 to 28 kg during two consecutive 18-wk lactation. These periods differed as the selected goats kidded between February and October each year (1978 1979). Management, housing, feeding, and composition of the grass and dairy concentrate given to these animals were identical (4). Blood Samples
Samples of blood were collected from the jugular vein of each doe during the two lactations. Blood samples (10 ml) were collected every other day during the first 6 days of lactation and thereafter on the 4th day of each week. Serum from individual animals was harvested and analyzed for Ca, P, Mg, Na, and K after wet digestion (in duplicates) of samples with a mixture of nitric, perchloric, and sulphuric acids with Perkin-Elmer atomic absorption spectrophotometer model 290. The P from the digest was measured as phosphovanadomolybdate (5), and the yellow color so developed was measured spectrophotometrically at 425 nm. Statistical analysis was according to Steel and Torrie (17). Evaluation of the trends in the data followed orthogonal polynomials of Fisher and Yates (10). R ESU LTS
Effects of the two lactation periods with trends on concentrations of Ca, P, Na, K, and Mg in blood were not significant (P>.05); hence, the two sets for each mineral were pooled. Each figure in Table 1 which corresponds to wk 2 to 18 is an average from accurately pipetted 1 ml blood serum, digested in duplicates, (a mean of 80 determinations). 874
TECHNICAL NOTE
875
results in w h i c h c o n c e n t r a t i o n s of Na a n d K were h i g h e r b u t Ca a n d P l o w e r in s e r u m d u r i n g the 1st wk o f l a c t a t i o n , a p e r i o d w h i c h corr e s p o n d e d t o p r o d u c t i o n o f c o l o s t r u m (4). Minerals in b l o o d in well-fed h e a l t h y animals is c o n t r o l l e d b y h o m e o s t a t i c m e c h a n i s m s w h i c h keep c o n t e n t s w i t h i n limits. A n y v a r i a t i o n w i t h i n a r e a s o n a b l e l i m i t can be i n f l u e n c e d b y dietary changes, e n v i r o n m e n t , gestation, lactation, a n d o t h e r m a n a g e m e n t f a c t o r s (7, 8, 11, 15). A n i m a l s were u n d e r t h e same feeding a n d m a n a g e m e n t c o n d i t i o n s w i t h m a x i m u m possible veterinary a t t e n t i o n against parasites a n d diseases. As in (4), does were served a t t h e 9 t h wk, w h i c h c o r r e s p o n d s t o t h e t h i r d h e a t (estrus), t h e first b e i n g 21 days (3 wk) a f t e r p a r t u r i t i o n . G e s t a t i o n p e r i o d is 5 too. E x p e r i e n c e (1) has shown that additional nutrient requirement d u r i n g p r e g n a n c y b e c o m e s critical d u r i n g t h e last 2 m o o f g e s t a t i o n w h e n p r e g n a n c y is 3 m o ( 1 2 wk) old. F o r every animal, l a c t a t i o n w o u l d
Day 1, 3, a n d 6 ( T a b l e 1) r e p r e s e n t e d samples t a k e n d u r i n g t h e colostral p e r i o d (4). B l o o d s e r u m was h i g h e r in Na, K, a n d Mg b u t l o w e r in Ca a n d P in t h e 1st w k a f t e r p a r t u r i t i o n as c o m p a r e d w i t h t h e c o r r e s p o n d i n g m e a n s for l a c t a t i o n periods (Table 1). T a b l e 1 s h o w s t h a t t h e Na, Ca, a n d P in the serum increased with advancing lactation. The overall results d e p i c t e d increasing l i n e a r t r e n d s ( P < . 0 1 ) . T r e n d s were n o t d i f f e r e n t for t h e 20 goats. However, t h e K a n d Mg c o n t e n t of the s e r u m d e c r e a s e d till t h e e n d of l a c t a t i o n . Decreasing t r e n d s c o u l d be d e s c r i b e d b y linear r e l a t i o n s h i p s ( P < . 0 1 ) w h i c h were n o t d i f f e r e n t f o r all does, b u t q u a d r a t i c t r e n d s were n o t significant (P> .05). DISCUSSION
We o b s e r v e d (2) t h a t c o l o s t r u m of g o a t was r i c h e r in Na a n d K b u t l o w e r in Ca a n d P t h a n milk. Such i n f o r m a t i o n seems to c o n f i r m
TABLE 1. Major elements in goats' blood with advancing lactation. Period after parturition
Ca
P (mg 1100 ml) SD
1st day 3rd day 6th day Mean a 2nd wk b 3rd wk 4th wk 5th wk 6th wk 7th wk 8th wk 9th wk lOth wk 11th wk 12th wk I3th wk 14th wk 15th wk 16th wk 17th wk 18th wk Mean c
8.81 8.56 8.02 8.46 8.02 8.13 8.62 9.14 9.35 9.56 10.04 10.81 11.12 11.13 11.20 11.41 11.63 11.84 12.05 12.32 12.50 10.52
SD
X
SD
.08 .06
3.80 3.81
.09 .04
148.23 147.90
.21 .24
.09
5.92
.09
3.60
.01
147.02
.20
.40 .19 .08 .10 .11 .07 .11 .09 .10 .11 .08 .11 .14 .08 .06 .07 .10 .07 1.47
6.05 5.92 6.01 6.02 6.32 6.81 7.00 7.00 7.34 7.81 7.21
.12 .01 .02 .01 .01
3.74 3.59 3.62 3.60 3.60 3.21 3.16 3.00 2.95 2.90 2.91 2.85 2.86 2.62 2.50 2.48 2.45 2.45
.12 .01 .03 .06 .04 .02 .05 .03 .04 .03 .07 .08 .03 .06 .05 .07 .06 .08
2.99
.42
147.72 135.02 135.20 135.20 136.10 136.42 138.31 138.82 139.11 139.42 139.80 141.32 142.64 144.55 143.80 144.35 145.69 145.88 140.10
.63 .29 .11 .101 .04 .70 .03 .84 .33 .24 .20 1.01 .82 .44 .39 .55 .60 .58 3.83
7.96
8.05 8.32 8.41 8.56 8.70 8.92 7.43
SD
K (meq/liter)
6.14 6.10
.15 .20
X
Na
Mg
.02
.03 .02 .01 .02 .03 .01 .02 .01 .02 .01 .01 .02 1,0
X
SD
6.52 6.30 6.30 6.28 5.91 5.90 5.62 5.45 5.01 4.92 4.80 4.94 4.86 4.62 4.71 4.64 4.83 4.70 4.66 4.68 4.53
.06 .11 .10 .25 .02 .04 .06 .03 .02 .07 .09 .04 1.01 .06 .04 .05 .08 .06 .100 .07 .06 .45
4.99
acolostral period: mean of 240 determinations. bEach weekly mean represents 80 determinations. CExcluding 1st wk after parturition. Journal of Dairy Science Vol. 65, No. 5, 1982
876
AKINSOYINU
have a d v a n c e d to w k 21 ( 1 2 + 9 wk). This is m o r e t h a n 18-wk l a c t a t i o n u n d e r c o n s i d e r a t i o n b e y o n d w h i c h t h e l a c t a t i n g goats h a d dried up. It, t h e r e f o r e , seems logical t h a t m e a n s for m i n e r a l s in s e r u m were n o t a f f e c t e d b y pregn a n c y w i t h i n t h e p e r i o d o f this study. V a r i o u s t r e n d s for Ca, P, Na, a n d K in b l o o d were, h o w e v e r , c o m p a r a b l e t o those r e p o r t e d f o r t h e s e m i n e r a l s in g o a t s ' m i l k (2) d u r i n g l a c t a t i o n . Since m i n e r a l s in m i l k o r i g i n a t e f r o m b l o o d (8, 18), i t appears r e a s o n a b l e t o i n f e r t h a t stage of l a c t a t i o n h a s the p r e d o m i n a n t e f f e c t o n b l o o d m i n e r a l w i t h i n t h e p e r i o d covered. Milk yield o f t h e s e goats r e a c h e d a p e a k at the 5th w k a f t e r p a r t u r i t i o n a n d t h e n d e c l i n e d till t h e e n d o f l a c t a t i o n (3). It follows t h a t t h e Ca, P, a n d Na o u t p u t f r o m b l o o d t o m i l k wilt decrease a n d so create an a v e n u e f o r an increase of t h e s e m i n e r a l s in t h e b l o o d w i t h advance in l a c t a t i o n . T h e r e is an inverse r e l a t i o n s h i p b e t w e e n Na a n d K in b l o o d (15). T h u s , an increase in Na was a c c o m p a n i e d b y a fall in K c o n t e n t of b l o o d w i t h l a c t a t i o n . T h e m e a n m g / 1 0 0 m l Ca a n d P were h i g h e r t h a n t h o s e r e p o r t e d for goats (19). Results (6, 19) also s h o w e d t h a t stage o f l a c t a t i o n h a d an a p p r e c i a b l e e f f e c t o n Ca a n d P in blood. T h e fall in weekly m e a n P b e t w e e n t h e 1 0 t h a n d l l t h a n d Na b e t w e e n t h e 1 4 t h a n d 1 5 t h w k d e v i a t e d f r o m increasing trends. T h e r e was n o t a n y e v i d e n c e o f loss of a p p e t i t e or sickness. C h a n c e m a y e x p l a i n it, as t h e decrease was n o t significant. Average Ca ( r a g / 1 0 0 m l ) in b l o o d s e r u m over l a c t a t i o n falls w i t h i n t h e range 7.7 t o 13.2 (11), a n d c o r r e s p o n d i n g m e a n P is h i g h e r t h a n 5.23 (11) b u t falls w=thin t h e r a n g e 4.3 to 7.7 (14) for l a c t a t i n g cows. T h e m i l k e q u i v a l e n t s p e r liter o f Na a n d K in t h e s e r u m fall w i t h i n t h e range 1 3 1 . 7 t o 1 4 7 . 8 for Na (7, 14) a n d 4.3 to 5.7 for K (14) in l a c t a t i n g cows. A c o m p a r a b l e t r e n d for Mg in s e r u m w i t h a d v a n c e in l a c t a t i o n also has b e e n r e p o r t e d f o r goats (6). ACKNOWLEDGMENT
T h e a u t h o r is grateful t o t h e University o f I b a d a n for f i n a n c i n g this p r o j e c t t h r o u g h t h e S e n a t e R e s e a r c h Grants. REFERENCES
1 Akinsoyinu, A. O. 1974. Studies on protein and energy utilization by the West African dwarf goats. Journal of Dairy Science Vol. 65, No. 5, 1982
Ph.D. thesis, Univ. Ibadan, Ibadan, Nigeria. 2 Akinsoyinu, A. O., and I. O. Akinyele 1979. Major elements in milk of the West African dwarf goats as affected by stage of lactation. J. Dairy Res. 46:427. 3 Akinsoyinu, A. O., A. U. Mba, and F. O. Olubajo 1977. Studies on milk yield and composition of the West African dwarf goat in Nigeria. J. Dairy Res. 44:57. 4 Akinsoyinu, A. O., O. O. Tewe, and A. U. Mba 1980. Concentration of trace elements in milk of West African dwarf goats affected by state of lactation. J. Dairy Sci. 62:921. 5 Association of Official Analytical Chemists 1970. Method of analysis, l l t h ed. AOAC, Washington, DC. 6 Barlet, J. P., M. C. Michel, P. Larvor, and M. Theriez 1971. Blood Ca, P, Mg and glucose in mother and newborn domestic ruminants. Ann. Biol. Anita. Biochim. Biophys. 11:415. 7 Cakala, S., T. Borkowski, A. Albrycht, and K. Bieniek 1972. Changes in minerals and alkaline phosphatose in serum and of ascorbic acid in blood of cows on pasture in spring Nutr. Abstr. Rev. 42:141. 8 Comar, C. L., and F. Bronner, 1962. Mineral metabolism. Vol. II. Part B. Academic Press, New York, NY. 9 Devendra, C., and M. Burns 1970. Goat production in the tropics. Techn. Comm. No. 19. Commonwealth Bur. Anim. Breeding Genet. 10 Fisher, R. A., and M. Yates 1963. Statistical tables for biological, agricultural and medical research. 6th ed. Oliver and Boyd, Edinburgh Tweeddale Court. 11 Kennedy, W. L., A. K. Anderson, S. B. Bechdel, and J. F. Shigley 1939. Studies on the composition of bovine blood as influenced by gestation, lactation and age. J. Dairy Sci. 22:251. 12 Parkash, S., and R. Jenness. 1968. The composition and Characteristics of goats milk. A review. J. Dairy Sci. 30:67. Abstr. 13 Razifard, R. 1972. An investigation on the levels of magnesium in blood plasma and milk of the lactating goats. J. Vet. Fac. Univ. Tehran 28:49. 14 Rowlands, G. J., W. Little, R. Manston, and S. M. Dew 1974. The effect of season on the composition of the blood of lactating and non lactating cows as revealed from repeated metabolic profile tests on 24 dairy herds. J. Agric. Sci. 83:27. 15 Rowlands, G. J., R. Manston, R. M. Pocock, and S. M. Dew 1975. Relationship between stage of lactation and pregnancy and blood composition in a herd of dairy cows and the influence of seasonal changes in management of these relationship. J. Dairy Res. 42: 349. 16 Smith, V. 1959. Physiology of lactation. 5th ed. Iowa State Univ. Press, Ames. 17 Steel, R.G.D., and J. H. Torrie 1960. Principles and procedures of statistics. McGraw-Hill, New York, NY. 18 Tyler, D. D. 1977. Water and mineral metabolism. In Review of physiological chemistry. H. A.,
TECHNICAL NOTE Harper, V. W. Rodwell, and P. A. Mayes, ed. Lange Med. Publ., Los Attos, CA. 19 Zamora, R. G., and C. L. Davide 1969. Calcium
877
and phosphorus contents of blood and milk of goats during the lactation period. Philippine Agric. 53:238.
Journal of Dairy Science Vol. 65, No. 5, 1982
AKINSOYINU
Department of Animal Science University of Ibadan
Ibadan, Nigeria ABSTRACT
Twenty
adult
West African
dwarf
(Fouta djallon) does about 2 yr old and weighing from 23 to 28 kg were kept for two 18-wk lactations. Blood samples were obtained once weekly from 2 to 18 wk of lactation except in the 1st wk after parturition when samples were every other day for chemical analysis. Blood serum from the 2nd to the 18th wk contained the following averages (mg/100 ml) with standard deviations: calcium 10.52, 1.47; phosphorus 7.43, 1.0; magnesium 2.99, .42; (meq/liter) sodium 140.10, 3.83; and potassium 4.99, .45. In blood during the 1st wk after parturition they were 8.46, .40; 6.05, .12; 3.74, .12; 147.72, .63; and 6.28, .25. Trends increased with advance in lactation except for magnesium and potassium, which decreased. INTRODUCTION
Studies on goats are receiving attention by scientists all over the world. This stems from the growing awareness of the need to accumulate information on goats, which have been neglected compared with sheep and carte (9). The paucity of information on performance and production by goats with special emphasis on tropical breeds has been highlighted (9). Attention also has been on characteristics and composition of goat milk and of West African dwarf (WAD) goats in particular (2, 3, 4). While there has been information on major and trace elements in milk of WAD goats (2, 4), little is on the concentration of these minerals in blood during lactation. Few experiments on Ca, P, and Mg in goat blood during lactation (13, 19) were on temperate breeds. Since mineral constituents in milk have been derived from blood
Received March 11, 1980. 1982 J Dairy Sci 65:874-877
(8, 16), such information will contribute to our basic knowledge on WAD goats as reported in this paper. MATERIALS AND METHODS Animals and Their Management
Experiments used 20 adult does approximately 2 yr old, weighing 23 to 28 kg during two consecutive 18-wk lactation. These periods differed as the selected goats kidded between February and October each year (1978 1979). Management, housing, feeding, and composition of the grass and dairy concentrate given to these animals were identical (4). Blood Samples
Samples of blood were collected from the jugular vein of each doe during the two lactations. Blood samples (10 ml) were collected every other day during the first 6 days of lactation and thereafter on the 4th day of each week. Serum from individual animals was harvested and analyzed for Ca, P, Mg, Na, and K after wet digestion (in duplicates) of samples with a mixture of nitric, perchloric, and sulphuric acids with Perkin-Elmer atomic absorption spectrophotometer model 290. The P from the digest was measured as phosphovanadomolybdate (5), and the yellow color so developed was measured spectrophotometrically at 425 nm. Statistical analysis was according to Steel and Torrie (17). Evaluation of the trends in the data followed orthogonal polynomials of Fisher and Yates (10). R ESU LTS
Effects of the two lactation periods with trends on concentrations of Ca, P, Na, K, and Mg in blood were not significant (P>.05); hence, the two sets for each mineral were pooled. Each figure in Table 1 which corresponds to wk 2 to 18 is an average from accurately pipetted 1 ml blood serum, digested in duplicates, (a mean of 80 determinations). 874
TECHNICAL NOTE
875
results in w h i c h c o n c e n t r a t i o n s of Na a n d K were h i g h e r b u t Ca a n d P l o w e r in s e r u m d u r i n g the 1st wk o f l a c t a t i o n , a p e r i o d w h i c h corr e s p o n d e d t o p r o d u c t i o n o f c o l o s t r u m (4). Minerals in b l o o d in well-fed h e a l t h y animals is c o n t r o l l e d b y h o m e o s t a t i c m e c h a n i s m s w h i c h keep c o n t e n t s w i t h i n limits. A n y v a r i a t i o n w i t h i n a r e a s o n a b l e l i m i t can be i n f l u e n c e d b y dietary changes, e n v i r o n m e n t , gestation, lactation, a n d o t h e r m a n a g e m e n t f a c t o r s (7, 8, 11, 15). A n i m a l s were u n d e r t h e same feeding a n d m a n a g e m e n t c o n d i t i o n s w i t h m a x i m u m possible veterinary a t t e n t i o n against parasites a n d diseases. As in (4), does were served a t t h e 9 t h wk, w h i c h c o r r e s p o n d s t o t h e t h i r d h e a t (estrus), t h e first b e i n g 21 days (3 wk) a f t e r p a r t u r i t i o n . G e s t a t i o n p e r i o d is 5 too. E x p e r i e n c e (1) has shown that additional nutrient requirement d u r i n g p r e g n a n c y b e c o m e s critical d u r i n g t h e last 2 m o o f g e s t a t i o n w h e n p r e g n a n c y is 3 m o ( 1 2 wk) old. F o r every animal, l a c t a t i o n w o u l d
Day 1, 3, a n d 6 ( T a b l e 1) r e p r e s e n t e d samples t a k e n d u r i n g t h e colostral p e r i o d (4). B l o o d s e r u m was h i g h e r in Na, K, a n d Mg b u t l o w e r in Ca a n d P in t h e 1st w k a f t e r p a r t u r i t i o n as c o m p a r e d w i t h t h e c o r r e s p o n d i n g m e a n s for l a c t a t i o n periods (Table 1). T a b l e 1 s h o w s t h a t t h e Na, Ca, a n d P in the serum increased with advancing lactation. The overall results d e p i c t e d increasing l i n e a r t r e n d s ( P < . 0 1 ) . T r e n d s were n o t d i f f e r e n t for t h e 20 goats. However, t h e K a n d Mg c o n t e n t of the s e r u m d e c r e a s e d till t h e e n d of l a c t a t i o n . Decreasing t r e n d s c o u l d be d e s c r i b e d b y linear r e l a t i o n s h i p s ( P < . 0 1 ) w h i c h were n o t d i f f e r e n t f o r all does, b u t q u a d r a t i c t r e n d s were n o t significant (P> .05). DISCUSSION
We o b s e r v e d (2) t h a t c o l o s t r u m of g o a t was r i c h e r in Na a n d K b u t l o w e r in Ca a n d P t h a n milk. Such i n f o r m a t i o n seems to c o n f i r m
TABLE 1. Major elements in goats' blood with advancing lactation. Period after parturition
Ca
P (mg 1100 ml) SD
1st day 3rd day 6th day Mean a 2nd wk b 3rd wk 4th wk 5th wk 6th wk 7th wk 8th wk 9th wk lOth wk 11th wk 12th wk I3th wk 14th wk 15th wk 16th wk 17th wk 18th wk Mean c
8.81 8.56 8.02 8.46 8.02 8.13 8.62 9.14 9.35 9.56 10.04 10.81 11.12 11.13 11.20 11.41 11.63 11.84 12.05 12.32 12.50 10.52
SD
X
SD
.08 .06
3.80 3.81
.09 .04
148.23 147.90
.21 .24
.09
5.92
.09
3.60
.01
147.02
.20
.40 .19 .08 .10 .11 .07 .11 .09 .10 .11 .08 .11 .14 .08 .06 .07 .10 .07 1.47
6.05 5.92 6.01 6.02 6.32 6.81 7.00 7.00 7.34 7.81 7.21
.12 .01 .02 .01 .01
3.74 3.59 3.62 3.60 3.60 3.21 3.16 3.00 2.95 2.90 2.91 2.85 2.86 2.62 2.50 2.48 2.45 2.45
.12 .01 .03 .06 .04 .02 .05 .03 .04 .03 .07 .08 .03 .06 .05 .07 .06 .08
2.99
.42
147.72 135.02 135.20 135.20 136.10 136.42 138.31 138.82 139.11 139.42 139.80 141.32 142.64 144.55 143.80 144.35 145.69 145.88 140.10
.63 .29 .11 .101 .04 .70 .03 .84 .33 .24 .20 1.01 .82 .44 .39 .55 .60 .58 3.83
7.96
8.05 8.32 8.41 8.56 8.70 8.92 7.43
SD
K (meq/liter)
6.14 6.10
.15 .20
X
Na
Mg
.02
.03 .02 .01 .02 .03 .01 .02 .01 .02 .01 .01 .02 1,0
X
SD
6.52 6.30 6.30 6.28 5.91 5.90 5.62 5.45 5.01 4.92 4.80 4.94 4.86 4.62 4.71 4.64 4.83 4.70 4.66 4.68 4.53
.06 .11 .10 .25 .02 .04 .06 .03 .02 .07 .09 .04 1.01 .06 .04 .05 .08 .06 .100 .07 .06 .45
4.99
acolostral period: mean of 240 determinations. bEach weekly mean represents 80 determinations. CExcluding 1st wk after parturition. Journal of Dairy Science Vol. 65, No. 5, 1982
876
AKINSOYINU
have a d v a n c e d to w k 21 ( 1 2 + 9 wk). This is m o r e t h a n 18-wk l a c t a t i o n u n d e r c o n s i d e r a t i o n b e y o n d w h i c h t h e l a c t a t i n g goats h a d dried up. It, t h e r e f o r e , seems logical t h a t m e a n s for m i n e r a l s in s e r u m were n o t a f f e c t e d b y pregn a n c y w i t h i n t h e p e r i o d o f this study. V a r i o u s t r e n d s for Ca, P, Na, a n d K in b l o o d were, h o w e v e r , c o m p a r a b l e t o those r e p o r t e d f o r t h e s e m i n e r a l s in g o a t s ' m i l k (2) d u r i n g l a c t a t i o n . Since m i n e r a l s in m i l k o r i g i n a t e f r o m b l o o d (8, 18), i t appears r e a s o n a b l e t o i n f e r t h a t stage of l a c t a t i o n h a s the p r e d o m i n a n t e f f e c t o n b l o o d m i n e r a l w i t h i n t h e p e r i o d covered. Milk yield o f t h e s e goats r e a c h e d a p e a k at the 5th w k a f t e r p a r t u r i t i o n a n d t h e n d e c l i n e d till t h e e n d o f l a c t a t i o n (3). It follows t h a t t h e Ca, P, a n d Na o u t p u t f r o m b l o o d t o m i l k wilt decrease a n d so create an a v e n u e f o r an increase of t h e s e m i n e r a l s in t h e b l o o d w i t h advance in l a c t a t i o n . T h e r e is an inverse r e l a t i o n s h i p b e t w e e n Na a n d K in b l o o d (15). T h u s , an increase in Na was a c c o m p a n i e d b y a fall in K c o n t e n t of b l o o d w i t h l a c t a t i o n . T h e m e a n m g / 1 0 0 m l Ca a n d P were h i g h e r t h a n t h o s e r e p o r t e d for goats (19). Results (6, 19) also s h o w e d t h a t stage o f l a c t a t i o n h a d an a p p r e c i a b l e e f f e c t o n Ca a n d P in blood. T h e fall in weekly m e a n P b e t w e e n t h e 1 0 t h a n d l l t h a n d Na b e t w e e n t h e 1 4 t h a n d 1 5 t h w k d e v i a t e d f r o m increasing trends. T h e r e was n o t a n y e v i d e n c e o f loss of a p p e t i t e or sickness. C h a n c e m a y e x p l a i n it, as t h e decrease was n o t significant. Average Ca ( r a g / 1 0 0 m l ) in b l o o d s e r u m over l a c t a t i o n falls w i t h i n t h e range 7.7 t o 13.2 (11), a n d c o r r e s p o n d i n g m e a n P is h i g h e r t h a n 5.23 (11) b u t falls w=thin t h e r a n g e 4.3 to 7.7 (14) for l a c t a t i n g cows. T h e m i l k e q u i v a l e n t s p e r liter o f Na a n d K in t h e s e r u m fall w i t h i n t h e range 1 3 1 . 7 t o 1 4 7 . 8 for Na (7, 14) a n d 4.3 to 5.7 for K (14) in l a c t a t i n g cows. A c o m p a r a b l e t r e n d for Mg in s e r u m w i t h a d v a n c e in l a c t a t i o n also has b e e n r e p o r t e d f o r goats (6). ACKNOWLEDGMENT
T h e a u t h o r is grateful t o t h e University o f I b a d a n for f i n a n c i n g this p r o j e c t t h r o u g h t h e S e n a t e R e s e a r c h Grants. REFERENCES
1 Akinsoyinu, A. O. 1974. Studies on protein and energy utilization by the West African dwarf goats. Journal of Dairy Science Vol. 65, No. 5, 1982
Ph.D. thesis, Univ. Ibadan, Ibadan, Nigeria. 2 Akinsoyinu, A. O., and I. O. Akinyele 1979. Major elements in milk of the West African dwarf goats as affected by stage of lactation. J. Dairy Res. 46:427. 3 Akinsoyinu, A. O., A. U. Mba, and F. O. Olubajo 1977. Studies on milk yield and composition of the West African dwarf goat in Nigeria. J. Dairy Res. 44:57. 4 Akinsoyinu, A. O., O. O. Tewe, and A. U. Mba 1980. Concentration of trace elements in milk of West African dwarf goats affected by state of lactation. J. Dairy Sci. 62:921. 5 Association of Official Analytical Chemists 1970. Method of analysis, l l t h ed. AOAC, Washington, DC. 6 Barlet, J. P., M. C. Michel, P. Larvor, and M. Theriez 1971. Blood Ca, P, Mg and glucose in mother and newborn domestic ruminants. Ann. Biol. Anita. Biochim. Biophys. 11:415. 7 Cakala, S., T. Borkowski, A. Albrycht, and K. Bieniek 1972. Changes in minerals and alkaline phosphatose in serum and of ascorbic acid in blood of cows on pasture in spring Nutr. Abstr. Rev. 42:141. 8 Comar, C. L., and F. Bronner, 1962. Mineral metabolism. Vol. II. Part B. Academic Press, New York, NY. 9 Devendra, C., and M. Burns 1970. Goat production in the tropics. Techn. Comm. No. 19. Commonwealth Bur. Anim. Breeding Genet. 10 Fisher, R. A., and M. Yates 1963. Statistical tables for biological, agricultural and medical research. 6th ed. Oliver and Boyd, Edinburgh Tweeddale Court. 11 Kennedy, W. L., A. K. Anderson, S. B. Bechdel, and J. F. Shigley 1939. Studies on the composition of bovine blood as influenced by gestation, lactation and age. J. Dairy Sci. 22:251. 12 Parkash, S., and R. Jenness. 1968. The composition and Characteristics of goats milk. A review. J. Dairy Sci. 30:67. Abstr. 13 Razifard, R. 1972. An investigation on the levels of magnesium in blood plasma and milk of the lactating goats. J. Vet. Fac. Univ. Tehran 28:49. 14 Rowlands, G. J., W. Little, R. Manston, and S. M. Dew 1974. The effect of season on the composition of the blood of lactating and non lactating cows as revealed from repeated metabolic profile tests on 24 dairy herds. J. Agric. Sci. 83:27. 15 Rowlands, G. J., R. Manston, R. M. Pocock, and S. M. Dew 1975. Relationship between stage of lactation and pregnancy and blood composition in a herd of dairy cows and the influence of seasonal changes in management of these relationship. J. Dairy Res. 42: 349. 16 Smith, V. 1959. Physiology of lactation. 5th ed. Iowa State Univ. Press, Ames. 17 Steel, R.G.D., and J. H. Torrie 1960. Principles and procedures of statistics. McGraw-Hill, New York, NY. 18 Tyler, D. D. 1977. Water and mineral metabolism. In Review of physiological chemistry. H. A.,
TECHNICAL NOTE Harper, V. W. Rodwell, and P. A. Mayes, ed. Lange Med. Publ., Los Attos, CA. 19 Zamora, R. G., and C. L. Davide 1969. Calcium
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and phosphorus contents of blood and milk of goats during the lactation period. Philippine Agric. 53:238.
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