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Correlations Between Parities for Lactation Traits in United States Dairy Goats1
Correlations Between Parities for Lactation Traits in United States Dairy Goats I M. G R O S S M A N , 2 R. L. F E R N A N D O , W. A. M O H A M M A D , A . K . A . A L l , and R. D. S H A N K S Department of Animal Sciences University of Illinois at Urbana-Champaign Urbana 61801 ABSTRACT
to design a more effective breeding and management program for goats. Ronningen (7) estimated rather high repeatabilities for milk yield and for fat yield of about .60. Iloeje et al. (5) reported repeatabilities for milk yield that ranged from .42 to .52 and for fat yield that ranged from .42 to .55 depending on breed. Kennedy et al. (6) found phenotypic correlations of about .95 between milk yield and milk fat yield and of about .70 between milk yield or fat yield and days in milk across breed groups of first lactation does in California. All et al. (1) presented within-herd phenotypic correlations between lactation and reproductive traits by parity. Objectives of this study were to estimate within-herd phenotypic correlations between parities for lactation traits and to estimate within-herd repeatabilities of these lactation traits for the five major breeds of dairy goats in the United States.
Correlations between parities for milk yield, fat yield, and days in milk were calculated across and within does for five breeds of United States dairy goats; Alpine, LaMancha, Saanen, and Toggenburg, using lactation records to January 1981. Records were initiated during 1966 through 1979 and had between 125 and 305 d in milk. Parities were first through fourth, and fifth or greater. Overall phenotypic correlations between the three lactation traits averaged across breed were .95 between milk and fat yield and about .60 between milk or fat yield and days in milk. Within-herd phenotypic partial correlations between parities 1 and 2 (the two parities with most data) averaged .47 for milk yield, .42 for fat yield, and .07 for days in milk. Components of variance due to herd averaged about 34% for milk yield and for fat yield and 23% for days in milk. Components of variance due to doe/herd averaged 28% for milk yield, 25% for fat yield, and 17% for days in milk. Repeatabilities averaged .42 for milk yield, .38 for fat yield, and .22 for days in milk.
MATERIALS AND METHODS
INTRODUCTION
Knowledge of phenotypic variances and covariances and of repeatabilities of lactation traits in dairy goats is necessary to understand better the relationship among these traits and
Received December 5, 1985. 1Supported in part by the Illinois Agricultural Experiment Station and the University of Illinois Research Board. Data were provided by Animal Improvement Programs Laboratory, US Department of Agriculture, Beltsville, MD. 2 Reprint requests. 1986 J Dairy Sci 69:1917--1921
Data were records on lactations that were between 125 and 305 d in length and were initiated from 1966 through 1979. Because of insufficient data on does kidding during 1966 through 1974, those does were assigned a kidding-year group of ~< 1974. Lactation numbers or parities were first through fourth, and fifth or greater. Lactation traits were milk yield, milk fat yield, and lactation length or days in milk. We considered only the five major dairy goat breeds: Alpine, LaMancha, Nubian, Saanen, and Toggenburg, irrespective of type of registration. To estimate phenotypic correlations, there were 29,908 lactation records available including 8936 Alpine, 2302 LaMancha, 9652 Nubian 4002 Saanen, and 5016 Toggenburg records. Phenotypic correlations among lactation traits were computed by breed. Within-herd phenotypic partial correlations between parities for milk yield, fat yield, and days in milk were
1917
1918
GROSSMAN ET AL.
computed by breed. Error degrees of freedom for estimating within-herd phenotypic correlations between parities are in Table 1 by breed. These degrees of freedom were used as statistical weights to compute average within-herd phenotypic correlations over breed. Correlations with insufficient data (zero degrees of freedom after fitting herd within state and country) were not computed. The statistical model used to estimate variance components necessary to obtain repeatability of milk yield, fat yield, and days in milk was Yijklm = // + Pi + Yj + PYij + Hk + Dkl + eijklrn, where /a is the overall mean; Pi, the fixed effect of parity (i = 1,2 ..... /> 5); Yj, the fixed effect of kidding year (j = ~<74,75 ..... 79); PYij, the interaction effect of parity with kidding year; Hk, the random effect of herd distributed with mean 0 and variance o~; Dkl, the random effect of doe within herd, distributed with mean 0 and variance o~; and eijklm, the random error distributed with mean 0 and variance ae2. Components of variance, a~, a~, and ae2, were estimated by Henderson's method 2 (4). Within-herd repeatability was computed as o
/(oi +
Distributions of the number of lactation records, herds, and does represented in the data used to estimate variance components are in Table 2 by breed. There were 32,947 lactation records available with an average per breed of 812 herds represented (LaManchas had the low of 366 herds and Nubians had the high of 1388 herds) and with an average per breed of 4447 does represented (LaManchas had the low of 1709 does and Nubians had the high of 7152 does). RESULTS A N D DISCUSSION
Phenotypic correlations among lactation traits (Table 3) averaged over breed were .95 between milk yield and fat yield (with little variation among breeds), .61 between milk yield and days in milk (with a range from .55 to .65), and .60 between fat yield and days in milk (with a range from 5 4 to .65). F o r Alpines and Toggenburgs, correlations with days in milk tended to be lower than average. Within-herd phenotypic correlations between adjacent parities for milk yield (Table 4) averaged .47 between parities 1 and 2, .55 between parities 2 and 3, .53 between 3 and 4, Journal of Dairy Science Vol. 69, No. 7, 1986
and .36 between parities 4 and 5. The increase in correlations around the third parity coincides with the tendency of dairy goats to reach their maximum milk yield at third or fourth lactation, depending on breed (3, 8). Correlations for milk yields between nonadjacent parities, such as 1 and 3 or 2 and 5, were generally smaller than between adjacent parities and decreased as distance between parities increased. These trends are consistent with those in dairy cattle (2). Within-herd phenotypic correlations between adjacent parities for fat yield (Table 5) averaged .42 between parities 1 and 2, again higher (.50) between parities 2 and 3 and (.49) between 3 and 4, and again lower (.31) between parities 4 and 5. As with milk yield, dairy goats tend to reach maximum fat yield at third or fourth lactation (3, 8), coinciding with the increase in correlations around third parity. Correlations for fat yield between nonadjacent parities were generally smaller than between adjacent parities and decreased as distance between parities increased. These trends are also consistent with those in dairy cattle (2). Within-herd phenotypic correlations between adjacent parities for days in milk (Table 6) averaged .07 between parities 1 and 2 and increased to .15 between parities 3 and 4 and between 4 and 5. For milk yield, variance components (Table 7) averaged 33% for herd, 28% for doe/herd, and 39% for error. LaMancha and Saanen breeds had higher than average percentage error variance. For fat yield, variance components (Table 8) averaged 34% for herd, 25% for doe/herd, and 41% for error. These results are similar to those for milk yield. The LaMancha breed had higher than average percentage error variance. For days in milk, variance components (Table 9) averaged 23% for herd, 17% for doe/herd, and 60% for error. Error variance was a higher proportion of the total variance for days in milk compared with milk or fat yield. LaManchas and Nubians had higher than average percentage error variances. Herd and doe/herd variances for days in milk were correspondingly lower than those for milk or fat yield. Within-herd repeatabilities (Table 10) averaged .42 for milk yield, .38 for fat yield (with Nubians and Saanens above average), and .22
LACTATION TRAITS IN DAIRY GOATS
1919
TABLE 1. Error degrees of freedom for estimating within-herd phenotypic correlations between parities by breed. Between parities Breed
1:2
1:3
Alpine LaMancha Nubian Saanen Toggenburg Average
896 187 748 412 602 569
308 50 243 119 221 188.2
1:4
1:5
2:3
2:4
2:5
3:4
104 7 71 41 80 60.6
37 . . .1 13 14 ... 21.3
593 114 467 217 375 353.2
196 24 129 71 135 111
70 ... 29 20 43 40.5
339 58 238 134 218 197.4
3:5
4:5
106 ... 54 29 73 65.5
154 20 85 41 105 81
1 Insufficient data.
TABLE 2. Distribution of lactation records, herds, and does by breed. Number Breed
Records
Herds
Does
Alpine LaMancha Nubian Saanen Toggenburg Total or mean
10,016 2377 10,215 4399 5940 32,947
1066 366 1388 608 633 812.2
6638 1709 7152 3003 3733 4447
TABLE 3. Phenotypic correlations between milk yield (MILK), fat yield (FAT), and days in milk (DIM). Lactation traits Breed
MILK: FAT
MILK:DIM
FAT:DIM
Alpine LaMancha Nubian Saanen Toggenburg Average
.94 .95 .95 .95 .95 .95
.60 .65 .61 .64 .55 .61
.57 .65 .62 .63 .54 .60
TABLE 4. Within-herd phenotypic correlations between parities for milk yield by breed. Between parities Breed
1:2
1:3
1:4
1:5
2:3
2:4
2:5
3:4
3:5
4:5
Alpine LaMancha Nubian Saanen Toggenburg Average
.48 .47 .45 .48 .48 .47
.35 .21 .40 .42 .43 .38
.39 .19 .17 .23 .37 .31
.12 ...1 --.04 --.16
.56 .60 .57 .54 .49 .55
.38 .71 .38 .31 .31 .37
.32
.59 .68 .45 .54 .48 .53
.29 . . . . .47 .42 .26 .33
.38 52 .25 .39 .36 .36
i03
ii9 .26 --.13 .21
1 Insufficient data. Journal of Dairy Science Vol. 69, No. 7, 1986
1920
GROSSMAN ET AL.
TABLE 5. Within-herd phenotypic correlations between parities for fat yield by breed. Between parities Breed
1:2
1:3
1:4
Alpine LaMancha Nubian Saanen Toggenburg Average
.43 .38 .39 .45 .43 .42
.32 .23 .39 .43 .42 .37
.41 .30 .22 .24 .39 .33
1:5
2:3
.05 . . .1 .09 -.24 . . . . --.01
.51 .57 .51 .53 45 .50
2:4
2:5
3:4
3:5
4:5
.31
.27
.69
. . . .
.51 61 .45 .52 ,46 .49
.18 . . . . .39 .41 .18 .25
.35 51 .37 .31 .31
.36 .31 .29 .33
.32 ,30 --.19 .16
.16
Insufficient data. TABLE 6. Within-herd phenotypic correlations between parities for days in milk by breed. Between parities Breed
1:2
1:3
1:4
Alpine LaMancha Nubian Saanen Toggenburg Average
.08 .09 .07 .01 .09 .07
.12 -.01 .05 .09 .04 .07
.04 -.01 -.06 .17 -.11 --.01
1
1:5
2:3
.07 . . .1 -.26 .17
.12 .25 .11 .05 -.003 .09
102
2:4
2:5
3:4
3:5
4:5
.01 - .01 .04 .26 .03 .05
.11 .-_ -.01 .10 -.14 .02
.12 .22 .21 .03 .19 .15
.11
.26 .23 -.03 .34 .06 .15
-.01 .11 -.17 .01
Insufficient data.
TABLE 7. Variance components for milk yield by breed.
Breed
Error mean square
Variance component Herd
Doe/herd
(kg 2 ) Alpine LaMancha Nubian Saanen Toggenburg Average
38,970 28,350 25,550 44,288 35,737 34,812.7
Error
(%) 33.4 30.7 35.8 28.7 38.5 33.4
27.9 26.6 29.0 31.5 25.0 28.0
38.7 42.7
35.2 39.8 36.5 38.6
TABLE 8. Variance components for fat yield by breed. Error mean Breed
square
Variance components Herd
Doe/herd
(kg 2 ) Alpine LaMancha Nubian Saanen Toggenburg Average
54 46 61 56 43 53.5
Journal of Dairy Science Vol. 69, No. 7, 1986
Error
(%) 34.9 25.9 38.5 32.3 38.6 34.0
23.7 23.9 25.3 29.8 22.6 25.1
41.4 50.2 36.2 37.9 38.8 40.9
LACTATION TRAITS IN DAIRY GOATS
1921
TABLE 9. Variance components for days in milk by breed.
Breed
Error mean square
Variance components Herd
Doe/herd
21.4 30.0 21.3 19.1 22.6 22.9
20.3 8.8 13.6 23.0 19.3 17.0
(kg 2 ) Alpine LaMancha Nubian Saanen Toggenburg Average
1059 1313 1655 1201 1064 1264.8
Error
(%) 58.3 61.2 65.1 57.9 58.1 60.1
TABLE 10. Within-herd repeatability of milk yield (MILK), fat yield (FAT), and days in milk (DIM) by breed.
Breed
Error df
MILK
Alpine LaMancha Nubian Saanen Toggenburg Average
3378 668 3063 1396 2207 2142.4
.42 .38 .45 .44 .41 .42
f o r d a y s in m i l k ( w i t h Alpines, Saanens, a n d T o g g e n b u r g s a b o v e average). T h e s e e s t i m a t e s are l o w e r t h a n t h o s e o f B u t c h e r a n d F r e e m a n (2) in c a t t l e a n d o f R o n n i n g e n (7) in g o a t s a n d r e a s o n a b l y c o n s i s t e n t w i t h w o r k b y Iloeje et al. (5) in w h i c h r e p e a t a b i l i t i e s averaged a b o u t .48 for m i l k yield a n d for f a t yield. R e p e a t a b i l i t y of days in m i l k is p r o b a b l y biased u p w a r d b e c a u s e t h e d i s t r i b u t i o n of days in m i l k was c o n s t r a i n e d to 305 d.
REFERENCES
Ali, A.K.A., W. A. Mohammad, M. Grossman, R. D. Shanks, and G. R. Wiggans. 1983. Relationships among lactation and reproduction traits of dairy goats. J. Dairy Sci. 66:1926.
2 3 4 5 6
7 8
Repeatability FAT
DIM
.36 .32 .41 .44 .37 .38
.26 .12 .17 .28 .25 .22
Butcher, D. F., and A. E. Freeman. 1968. Heritability and repeatabilities of milk and milk fat production by lactations. J. Dairy Sci. 51 : 1387. Grossman, M., and G. R. Wiggans. 1980. Dairy goat lactation records and potential for buck evaluation. J. Dairy Sci. 63:1925. Henderson, C. R. 1953. Estimation of variance and covariance components. Biometrics 9:266. lloeje, M. U., L. D. Van Vleck, and G. R. Wiggans. 1981. Components of variance for milk and fat yields in dairy goats. J. Dairy Sci. 64:2290. Kennedy, B. W., C. M. Finley, and G. E. Bradford. 1982. Phenotypic and genetic relationships between reproduction and milk production in dairy goats. J. Dairy Sci. 65:2373. Ronningen, K. 1967. A study of genetic parameters for milk characteristics in goats. Meld. Nor. Landbrukshogsk. 46(2): 17. Ronningen, K., and T. Gjedrem. 1966. Effect of age and season of kidding on milk yield in goat. Meld. Nor. Landbrukshogsk. 45(21):17.
Journal of Dairy Science Vol. 69, No. 7, 1986
to design a more effective breeding and management program for goats. Ronningen (7) estimated rather high repeatabilities for milk yield and for fat yield of about .60. Iloeje et al. (5) reported repeatabilities for milk yield that ranged from .42 to .52 and for fat yield that ranged from .42 to .55 depending on breed. Kennedy et al. (6) found phenotypic correlations of about .95 between milk yield and milk fat yield and of about .70 between milk yield or fat yield and days in milk across breed groups of first lactation does in California. All et al. (1) presented within-herd phenotypic correlations between lactation and reproductive traits by parity. Objectives of this study were to estimate within-herd phenotypic correlations between parities for lactation traits and to estimate within-herd repeatabilities of these lactation traits for the five major breeds of dairy goats in the United States.
Correlations between parities for milk yield, fat yield, and days in milk were calculated across and within does for five breeds of United States dairy goats; Alpine, LaMancha, Saanen, and Toggenburg, using lactation records to January 1981. Records were initiated during 1966 through 1979 and had between 125 and 305 d in milk. Parities were first through fourth, and fifth or greater. Overall phenotypic correlations between the three lactation traits averaged across breed were .95 between milk and fat yield and about .60 between milk or fat yield and days in milk. Within-herd phenotypic partial correlations between parities 1 and 2 (the two parities with most data) averaged .47 for milk yield, .42 for fat yield, and .07 for days in milk. Components of variance due to herd averaged about 34% for milk yield and for fat yield and 23% for days in milk. Components of variance due to doe/herd averaged 28% for milk yield, 25% for fat yield, and 17% for days in milk. Repeatabilities averaged .42 for milk yield, .38 for fat yield, and .22 for days in milk.
MATERIALS AND METHODS
INTRODUCTION
Knowledge of phenotypic variances and covariances and of repeatabilities of lactation traits in dairy goats is necessary to understand better the relationship among these traits and
Received December 5, 1985. 1Supported in part by the Illinois Agricultural Experiment Station and the University of Illinois Research Board. Data were provided by Animal Improvement Programs Laboratory, US Department of Agriculture, Beltsville, MD. 2 Reprint requests. 1986 J Dairy Sci 69:1917--1921
Data were records on lactations that were between 125 and 305 d in length and were initiated from 1966 through 1979. Because of insufficient data on does kidding during 1966 through 1974, those does were assigned a kidding-year group of ~< 1974. Lactation numbers or parities were first through fourth, and fifth or greater. Lactation traits were milk yield, milk fat yield, and lactation length or days in milk. We considered only the five major dairy goat breeds: Alpine, LaMancha, Nubian, Saanen, and Toggenburg, irrespective of type of registration. To estimate phenotypic correlations, there were 29,908 lactation records available including 8936 Alpine, 2302 LaMancha, 9652 Nubian 4002 Saanen, and 5016 Toggenburg records. Phenotypic correlations among lactation traits were computed by breed. Within-herd phenotypic partial correlations between parities for milk yield, fat yield, and days in milk were
1917
1918
GROSSMAN ET AL.
computed by breed. Error degrees of freedom for estimating within-herd phenotypic correlations between parities are in Table 1 by breed. These degrees of freedom were used as statistical weights to compute average within-herd phenotypic correlations over breed. Correlations with insufficient data (zero degrees of freedom after fitting herd within state and country) were not computed. The statistical model used to estimate variance components necessary to obtain repeatability of milk yield, fat yield, and days in milk was Yijklm = // + Pi + Yj + PYij + Hk + Dkl + eijklrn, where /a is the overall mean; Pi, the fixed effect of parity (i = 1,2 ..... /> 5); Yj, the fixed effect of kidding year (j = ~<74,75 ..... 79); PYij, the interaction effect of parity with kidding year; Hk, the random effect of herd distributed with mean 0 and variance o~; Dkl, the random effect of doe within herd, distributed with mean 0 and variance o~; and eijklm, the random error distributed with mean 0 and variance ae2. Components of variance, a~, a~, and ae2, were estimated by Henderson's method 2 (4). Within-herd repeatability was computed as o
/(oi +
Distributions of the number of lactation records, herds, and does represented in the data used to estimate variance components are in Table 2 by breed. There were 32,947 lactation records available with an average per breed of 812 herds represented (LaManchas had the low of 366 herds and Nubians had the high of 1388 herds) and with an average per breed of 4447 does represented (LaManchas had the low of 1709 does and Nubians had the high of 7152 does). RESULTS A N D DISCUSSION
Phenotypic correlations among lactation traits (Table 3) averaged over breed were .95 between milk yield and fat yield (with little variation among breeds), .61 between milk yield and days in milk (with a range from .55 to .65), and .60 between fat yield and days in milk (with a range from 5 4 to .65). F o r Alpines and Toggenburgs, correlations with days in milk tended to be lower than average. Within-herd phenotypic correlations between adjacent parities for milk yield (Table 4) averaged .47 between parities 1 and 2, .55 between parities 2 and 3, .53 between 3 and 4, Journal of Dairy Science Vol. 69, No. 7, 1986
and .36 between parities 4 and 5. The increase in correlations around the third parity coincides with the tendency of dairy goats to reach their maximum milk yield at third or fourth lactation, depending on breed (3, 8). Correlations for milk yields between nonadjacent parities, such as 1 and 3 or 2 and 5, were generally smaller than between adjacent parities and decreased as distance between parities increased. These trends are consistent with those in dairy cattle (2). Within-herd phenotypic correlations between adjacent parities for fat yield (Table 5) averaged .42 between parities 1 and 2, again higher (.50) between parities 2 and 3 and (.49) between 3 and 4, and again lower (.31) between parities 4 and 5. As with milk yield, dairy goats tend to reach maximum fat yield at third or fourth lactation (3, 8), coinciding with the increase in correlations around third parity. Correlations for fat yield between nonadjacent parities were generally smaller than between adjacent parities and decreased as distance between parities increased. These trends are also consistent with those in dairy cattle (2). Within-herd phenotypic correlations between adjacent parities for days in milk (Table 6) averaged .07 between parities 1 and 2 and increased to .15 between parities 3 and 4 and between 4 and 5. For milk yield, variance components (Table 7) averaged 33% for herd, 28% for doe/herd, and 39% for error. LaMancha and Saanen breeds had higher than average percentage error variance. For fat yield, variance components (Table 8) averaged 34% for herd, 25% for doe/herd, and 41% for error. These results are similar to those for milk yield. The LaMancha breed had higher than average percentage error variance. For days in milk, variance components (Table 9) averaged 23% for herd, 17% for doe/herd, and 60% for error. Error variance was a higher proportion of the total variance for days in milk compared with milk or fat yield. LaManchas and Nubians had higher than average percentage error variances. Herd and doe/herd variances for days in milk were correspondingly lower than those for milk or fat yield. Within-herd repeatabilities (Table 10) averaged .42 for milk yield, .38 for fat yield (with Nubians and Saanens above average), and .22
LACTATION TRAITS IN DAIRY GOATS
1919
TABLE 1. Error degrees of freedom for estimating within-herd phenotypic correlations between parities by breed. Between parities Breed
1:2
1:3
Alpine LaMancha Nubian Saanen Toggenburg Average
896 187 748 412 602 569
308 50 243 119 221 188.2
1:4
1:5
2:3
2:4
2:5
3:4
104 7 71 41 80 60.6
37 . . .1 13 14 ... 21.3
593 114 467 217 375 353.2
196 24 129 71 135 111
70 ... 29 20 43 40.5
339 58 238 134 218 197.4
3:5
4:5
106 ... 54 29 73 65.5
154 20 85 41 105 81
1 Insufficient data.
TABLE 2. Distribution of lactation records, herds, and does by breed. Number Breed
Records
Herds
Does
Alpine LaMancha Nubian Saanen Toggenburg Total or mean
10,016 2377 10,215 4399 5940 32,947
1066 366 1388 608 633 812.2
6638 1709 7152 3003 3733 4447
TABLE 3. Phenotypic correlations between milk yield (MILK), fat yield (FAT), and days in milk (DIM). Lactation traits Breed
MILK: FAT
MILK:DIM
FAT:DIM
Alpine LaMancha Nubian Saanen Toggenburg Average
.94 .95 .95 .95 .95 .95
.60 .65 .61 .64 .55 .61
.57 .65 .62 .63 .54 .60
TABLE 4. Within-herd phenotypic correlations between parities for milk yield by breed. Between parities Breed
1:2
1:3
1:4
1:5
2:3
2:4
2:5
3:4
3:5
4:5
Alpine LaMancha Nubian Saanen Toggenburg Average
.48 .47 .45 .48 .48 .47
.35 .21 .40 .42 .43 .38
.39 .19 .17 .23 .37 .31
.12 ...1 --.04 --.16
.56 .60 .57 .54 .49 .55
.38 .71 .38 .31 .31 .37
.32
.59 .68 .45 .54 .48 .53
.29 . . . . .47 .42 .26 .33
.38 52 .25 .39 .36 .36
i03
ii9 .26 --.13 .21
1 Insufficient data. Journal of Dairy Science Vol. 69, No. 7, 1986
1920
GROSSMAN ET AL.
TABLE 5. Within-herd phenotypic correlations between parities for fat yield by breed. Between parities Breed
1:2
1:3
1:4
Alpine LaMancha Nubian Saanen Toggenburg Average
.43 .38 .39 .45 .43 .42
.32 .23 .39 .43 .42 .37
.41 .30 .22 .24 .39 .33
1:5
2:3
.05 . . .1 .09 -.24 . . . . --.01
.51 .57 .51 .53 45 .50
2:4
2:5
3:4
3:5
4:5
.31
.27
.69
. . . .
.51 61 .45 .52 ,46 .49
.18 . . . . .39 .41 .18 .25
.35 51 .37 .31 .31
.36 .31 .29 .33
.32 ,30 --.19 .16
.16
Insufficient data. TABLE 6. Within-herd phenotypic correlations between parities for days in milk by breed. Between parities Breed
1:2
1:3
1:4
Alpine LaMancha Nubian Saanen Toggenburg Average
.08 .09 .07 .01 .09 .07
.12 -.01 .05 .09 .04 .07
.04 -.01 -.06 .17 -.11 --.01
1
1:5
2:3
.07 . . .1 -.26 .17
.12 .25 .11 .05 -.003 .09
102
2:4
2:5
3:4
3:5
4:5
.01 - .01 .04 .26 .03 .05
.11 .-_ -.01 .10 -.14 .02
.12 .22 .21 .03 .19 .15
.11
.26 .23 -.03 .34 .06 .15
-.01 .11 -.17 .01
Insufficient data.
TABLE 7. Variance components for milk yield by breed.
Breed
Error mean square
Variance component Herd
Doe/herd
(kg 2 ) Alpine LaMancha Nubian Saanen Toggenburg Average
38,970 28,350 25,550 44,288 35,737 34,812.7
Error
(%) 33.4 30.7 35.8 28.7 38.5 33.4
27.9 26.6 29.0 31.5 25.0 28.0
38.7 42.7
35.2 39.8 36.5 38.6
TABLE 8. Variance components for fat yield by breed. Error mean Breed
square
Variance components Herd
Doe/herd
(kg 2 ) Alpine LaMancha Nubian Saanen Toggenburg Average
54 46 61 56 43 53.5
Journal of Dairy Science Vol. 69, No. 7, 1986
Error
(%) 34.9 25.9 38.5 32.3 38.6 34.0
23.7 23.9 25.3 29.8 22.6 25.1
41.4 50.2 36.2 37.9 38.8 40.9
LACTATION TRAITS IN DAIRY GOATS
1921
TABLE 9. Variance components for days in milk by breed.
Breed
Error mean square
Variance components Herd
Doe/herd
21.4 30.0 21.3 19.1 22.6 22.9
20.3 8.8 13.6 23.0 19.3 17.0
(kg 2 ) Alpine LaMancha Nubian Saanen Toggenburg Average
1059 1313 1655 1201 1064 1264.8
Error
(%) 58.3 61.2 65.1 57.9 58.1 60.1
TABLE 10. Within-herd repeatability of milk yield (MILK), fat yield (FAT), and days in milk (DIM) by breed.
Breed
Error df
MILK
Alpine LaMancha Nubian Saanen Toggenburg Average
3378 668 3063 1396 2207 2142.4
.42 .38 .45 .44 .41 .42
f o r d a y s in m i l k ( w i t h Alpines, Saanens, a n d T o g g e n b u r g s a b o v e average). T h e s e e s t i m a t e s are l o w e r t h a n t h o s e o f B u t c h e r a n d F r e e m a n (2) in c a t t l e a n d o f R o n n i n g e n (7) in g o a t s a n d r e a s o n a b l y c o n s i s t e n t w i t h w o r k b y Iloeje et al. (5) in w h i c h r e p e a t a b i l i t i e s averaged a b o u t .48 for m i l k yield a n d for f a t yield. R e p e a t a b i l i t y of days in m i l k is p r o b a b l y biased u p w a r d b e c a u s e t h e d i s t r i b u t i o n of days in m i l k was c o n s t r a i n e d to 305 d.
REFERENCES
Ali, A.K.A., W. A. Mohammad, M. Grossman, R. D. Shanks, and G. R. Wiggans. 1983. Relationships among lactation and reproduction traits of dairy goats. J. Dairy Sci. 66:1926.
2 3 4 5 6
7 8
Repeatability FAT
DIM
.36 .32 .41 .44 .37 .38
.26 .12 .17 .28 .25 .22
Butcher, D. F., and A. E. Freeman. 1968. Heritability and repeatabilities of milk and milk fat production by lactations. J. Dairy Sci. 51 : 1387. Grossman, M., and G. R. Wiggans. 1980. Dairy goat lactation records and potential for buck evaluation. J. Dairy Sci. 63:1925. Henderson, C. R. 1953. Estimation of variance and covariance components. Biometrics 9:266. lloeje, M. U., L. D. Van Vleck, and G. R. Wiggans. 1981. Components of variance for milk and fat yields in dairy goats. J. Dairy Sci. 64:2290. Kennedy, B. W., C. M. Finley, and G. E. Bradford. 1982. Phenotypic and genetic relationships between reproduction and milk production in dairy goats. J. Dairy Sci. 65:2373. Ronningen, K. 1967. A study of genetic parameters for milk characteristics in goats. Meld. Nor. Landbrukshogsk. 46(2): 17. Ronningen, K., and T. Gjedrem. 1966. Effect of age and season of kidding on milk yield in goat. Meld. Nor. Landbrukshogsk. 45(21):17.
Journal of Dairy Science Vol. 69, No. 7, 1986