University of Nebraska - Lincoln
DigitalCommons@University of Nebraska - Lincoln
Faculty Papers and Publications in Animal Science
Animal Science Department
January 1979
Projection Factors for Goat Lactation Records
G. R. Wiggans
US Department of Agriculture, Beltsville, MD
L. Dale Van Vleck
University of Nebraska - Lincoln, [email protected]
F. N. Dickinson
US Department of Agriculture, Beltsville, MD
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Wiggans, G. R.; Van Vleck, L. Dale; and Dickinson, F. N., "Projection Factors for Goat Lactation Records" (1979). Faculty Papers and
Publications in Animal Science. Paper 371.
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Projection Factors for Goat Lactation Records
G. R. W I G G A N S 1 , L. D. V A N V L E C K 2 ,
and F. N. D I C K I N S O N a
Animal Improvement ProgramsLaboratory
Agricultural Research
Science and Education Administration
US Department of Agriculture
Beltsville, M D 20705
and
Department of Animal Science
Cornell Universiw
Ithaca, N Y 14853
ABSTRACT
Projection factors based on production
on the last day of sampling were developed
for dairy goat milk and fat records. The
305-day lactation was divided into 13
stages varying from 10 to 40 days. The
shortest stages were in early lactation.
Sets of factors were developed for four
ages at freshening, two seasons, two levels
of herd production, and two breed
groups. These classifications were necessary to avoid bias and improve accuracy.
Cumulative yield factors also were
developed with the same grouping of
records. These factors are used when
production for the last sample day is not
available.
INTRODUCTION
The Dairy Herd Improvement program
gradually has been adapted to improve service
to goat herds. Dairy record processing centers
(DRPC) have adapted their computing systems
to process dairy goat records. Some aspects of
the processing service rely on research results
that are not available for goats. Partial records
of cows routinely are extended to a 305-day
equivalent to facilitate comparisons among
records of different lengths. This has not been
possible for dairy goat records. The purpose of
this study was to develop factors appropriate
for projecting dairy goat records to a 305-day
standard. This standard may not be the most
appropriate for goats because of large varia-
Received May 22, 1978.
1Animal Improvement Programs Laboratory.
2Department of Animal Science.
1979 J Dairy Sci 62:797-801
tion in length of production period. Many goats
stop lactating before 305 days. The selection of
a shorter standard period would reduce this
variation; however, the 305-day standard is
accepted by the American Dairy Goat Association.
Research by Steine (1) indicated that the
best method of extending dairy goat records
was to predict the remaining yield with a factor
times the production on the last day of sampling
and to add this prediction to the partial record
instead of using a factor times the partial record
to predict 305-day yield. Work on dairy cattle
records (2) confirmed that reduction in error
variance is possible with the last-sample day
method. In order to apply this technique
to goat records, allowance must be made for
environmental factors specifically affecting the
projection of goat records. Adapting the
findings from dairy cattle, last-sample day
factors were developed for dairy goat records.
MATERIALS AND METHODS
Milk and fat production on day of sampling
were from dairy goat records processed at the
Utah, New York, and Wisconsin DRPC. Records
on 3707 lactations were available which met
the following requirements: 1) 30 to 305
days in milk, 2) a normal termination, 3) a
sample day within 55 days of parturition, 4) 8
to 104 mo of age at parturition, and 5) a 12-mo
herd average record available on the herd.
Alpines, La Manchas, Saanens, Toggenburgs,
Nubians, and Crossbreds were represented.
The 305-day yields and partial yields through
each sample day were computed from yields on
sample day without adjustments to the first,
second, and last-sample periods because factors
appropriate for dairy goat records had not
797
798
W|GGANS ET AL.
b e e n derived. T h e ratio o f average r e m a i n i n g
y i e l d t o t h e average o f p r o d u c t i o n o n t h e
last-sample d a y t i m e s days r e m a i n i n g (305
m i n u s days in milk) was c o m p u t e d f o r subclasses
o f age, season, stage o f lactation, breed, trait,
a n d h e r d p r o d u c t i o n . T h e 305-day yield is
p r e d i c t e d as Y30 s = Yn + F a c t o r • LP • (305-n),
w h e r e Yn is t h e c u m u l a t i v e y i e l d t o t h e n t h day
in milk w i t h a yield o f LP o n t h a t day. Changes
in this ratio f r o m g r o u p t o g r o u p a n d t h e
n u m b e r o f r e c o r d s available w e r e c o n s i d e r e d in
final d e f i n i t i o n s o f groups. T o p r o v i d e f a c t o r s
to project records when production on the
last-sample d a y is n o t available, c u m u l a t i v e
y i e l d f a c t o r s also w e r e d e v e l o p e d w i t h t h e s a m e
g r o u p i n g s as t h e last-sample factors. T h e
average y i e l d o f t h e partial r e c o r d is s u b s t i t u t e d
f o r p r o d u c t i o n o n t h e last s a m p l e - d a y in
this case. T h e 305-day yield is p r e d i c t e d w i t h a
f a c t o r f o r c u m u l a t i v e yield as:
A
Y30s = Yn + F a c t o r • ( Y n / n ) . ( 3 O S - n )
= [1 + F a c t o r ' ( 3 0 5 - n ) / n ] "Yn"
T h e last p a r t o f t h e e x p r e s s i o n illustrates h o w
TABLE 1. Last-sample day factorsa for milk records of goat breeds other than Nubian.
8 to 1 9 m o b
Herd
yield
< 726 kg
Day at
end of
stage
15
25
35
55
95
135
165
195
215
235
255
275
305
20 to 3 1 m o b
32 to 5 5 m o b
56mo b
Apt
to
Oct c
Nov
to
Mar c
Apr
to
Oct c
Nov
to
Mar c
Apr
to
Oct c
Nov
to
Mar c
Apt
to
Oct c
.95
.72
.80
.65
.78
.72
.69
.66
.69
.72
.72
.74
.61
.55
.52
.56
.58
.59
.68
.71
.69
.64
.63
.64
.65
.65
.66
.62
.57
.57
.55
.55
.57
.61
.64
.67
.71
.74
.76
.76
.64
.62
.61
.60
.59
.61
.63
.67
.68
.71
.73
.76
.81
.59
.59
.58
.56
.55
.56
.58
.61
.63
.66
.69
.75
.75
.52
.52
.50
.50
.49
.50
.52
.54
.62
.62
.69
.74
.77
.76
.67
.81
.86
.94
.86
.82
.80
.69
.73
.82
.77
.68
.68
.64
.63
.62
.63
.63
.66
.66
.67
.70
.79
35
79
99
91
104
75
60
42
15
25
35
55
95
135
165
195
215
235
255
275
305
1.09
1.00
.97
.87
.83
.82
.81
.83
.84
.85
.88
.86
.82
.85
.84
.72
.69
.65
.68
.70
.72
.75
.76
.79
.84
.85
.91
.87
.79
.79
.73
.74
.75
.74
.73
.69
.65
.65
.68
.70
.86
.79
.75
.73
.71
.70
.73
.77
.71
.73
.76
.77
.79
.80
.81
.80
.84
.86
.89
.82
.74
.76
.70
.69
.65
.63
.63
.66
.66
.69
.75
.76
.79
.81
.83
.80
.73
.71
.69
.69
.68
.71
.72
.73
.73
.73
.71
.71
.68
.65
.59
.58
.56
.60
.61
.64
.68
.73
.76
.88
.83
Number d
344
305
536
236
618
294
394
179
Number d
726 kg
Nov
to
Marc
.77
.77
.79
.77
aEstimated 305-day yields = part yield + Factor • (last-sample day yield) • (305 - length of part record).
bAge at kidding.
CMonth of kidding.
dNumber of sample day production records used for the 96 to 135-day stage.
Journal of Dairy Science Vol. 62, No. 5, 1979
TECHNICAL NOTE
t h e t r a d i t i o n a l f a c t o r s f o r c u m u l a t i v e yield can
be p r o d u c e d f r o m t h e s e factors.
RESULTS AND DISCUSSION
Last-sample f a c t o r s for milk yield are in
Tables 1 a n d 2. T h e i n f l u e n c e o f age is s h o w n
b y t h e gradual r e d u c t i o n in size o f t h e f a c t o r
with increasing age o f doe. T h e 13 stages are o f
varying l e n g t h s t o a c c o m m o d a t e early rapid
change and t h e m i d d l e p e r i o d o f little change.
T h e factors decline rapidly until a r o u n d 100
days in milk and t h e n increase gradually. In
groups in w h i c h t h e factors did n o t f o l l o w a
799
s m o o t h curve, the factors w e r e s m o o t h e d . T h e
d e c l i n e in t h e f a c t o r s early in l a c t a t i o n m a y
r e f l e c t a gradual increase in daily yield w h i c h
causes the average daily r e m a i n i n g yield t o b e a
smaller f r a c t i o n o f t h e last-sample yield. T h e
rise t o w a r d t h e e n d m a y be d u e t o t h e s h o r t e n ing o f t h e p e r i o d b e t w e e n t h e l a s t - s a m p l e day
and the middle of the remaining period, the
p o i n t w h e n t h e average p r o d u c t i o n f o r t h e r e s t
o f lactation w o u l d be e x p e c t e d . As this p e r i o d
b e c o m e s s h o r t e r , t h o s e yields b e c o m e m o r e
similar. T h e d i f f e r e n c e b e t w e e n w i n t e r and
s p r i n g k i d d i n g is m o s t a p p a r e n t early in l a c t a t i o n
and declines as l a c t a t i o n progresses. G o a t s are
TABLE 2. Last-sample day factorsa for Nubian milk records.
8 to 19 mo b
Herd
yield
< 726 kg
726 kg
20 to 31 mo b
32 to 55 mo b
56 mo b
Day at
end of
stage
Nov
to
MarC
Apr
to
OctC
Nov
to
Marc
Apr
to
OetC
Nov
to
Marc
Apr
to
Oct c
Nov
to
Marc
Apr
to
Oct c
15
25
35
55
95
135
165
195
215
235
255
275
305
.79
.76
.73
.71
.66
.69
.70
.70
.72
.74
.81
.78
.88
.53
.51
.48
.43
.42
.41
.43
.56
.57
.72
.72
.69
.69
.73
.67
.63
.57
.60
.63
.57
.59
.54
.65
.70
.82
.84
.69
.62
.53
.50
.51
.52
.55
.60
.65
.73
.82
.87
.87
.62
.59
.58
.58
.58
.60
.59
.60
.57
.56
.63
.61
.62
.55
.53
.54
.50
.53
.52
.64
.64
.67
.72
.73
.76
.72
.60
.56
.55
.52
.52
.50
.45
.40
.49
.52
.54
.58
.60
.61
.50
.48
.45
.44
.44
.44
.44
.50
.51
.55
.59
.65
Number d
27
90
79
49
75
47
38
27
15
25
35
55
95
135
165
195
215
235
255
275
305
.91
.88
.84
.79
.74
.73
.73
.73
.73
.76
.79
.76
.70
.84
.69
.66
.64
.59
.57
.61
.61
.61
,61
.68
.71
,80
.78
.78
.76
.72
.69
.69
.70
.76
.77
.78
.79
.83
.70
.73
.78
.74
.70
.63
.61
.63
.63
.63
.63
.66
.69
.71
.74
.72
,70
.64
.64
.64
.64
.64
.67
,68
.76
.72
,65
.68
.58
.56
.55
.51
.52
.52
.52
.52
.52
.53
.67
,72
.71
.71
.66
.63
.60
.61
.61
.62
.62
.62
.65
.79
.68
.48
.48
,48
.44
.44
.42
.42
.42
.50
.53
.63
,64
.64
Number d
65
78
91
50
103
63
56
20
aEstimated 305-day yields = part yield + Factor • (last-sample day yield) ° (305 - length of part record).
bAge at kidding.
CMonth of kidding.
dNumber of sample day production records used for the 96 to 135-day stage.
Journal of Dairy Science Vol, 62, No. 5, 1979
800
WIGGANS ET AL.
largely seasonal; f e w k i d in s u m m e r o r fall. T h e
r e c o r d s f r o m t h e s e off-season k i d d i n g s are
h i g h l y variable, especially in t o t a l n u m b e r o f
clays in milk. T h e r e f o r e , f a c t o r s will b e less
a c c u r a t e for t h e s e records.
N u b i a n s are relatively l o w e r t h a n o t h e r
b r e e d s in m i l k p r o d u c t i o n a n d h i g h e r in p e r c e n t age o f fat. T h e s e d i f f e r e n c e s also were r e f l e c t e d
in t h e factors so t h a t a s e p a r a t e set in T a b l e 2
was r e q u i r e d f o r N u b i a n s . T h e o t h e r b r e e d s
d i f f e r e d little. Herd p r o d u c t i o n was u s e d to
i m p r o v e t h e a c c u r a c y o f t h e f a c t o r s ; 7 2 6 k g was
selected to distinguish between commercial
o p e r a t i o n s in w h i c h m o s t goats w o u l d m i l k f o r
10 m o a n d l o w e r p r o d u c i n g u n i t s in w h i c h t h e
a n t i c i p a t e d p r o d u c t i o n is c o r r e s p o n d i n g l y lower.
A c o m p a r i s o n o f f a c t o r s iUustrates t h e sizable
d i f f e r e n c e b e t w e e n t h e s e groups. Milk a n d f a t
r e q u i r e s e p a r a t e sets o f f a c t o r s b e c a u s e o f t h e
c h a n g e in t h e p e r c e n t a g e o f f a t in t h e m i l k
over the course of lactation. Factors for fat
yield are in T a b l e s 3 a n d 4.
F a c t o r s f o r c u m u l a t i v e yield o f m i l k (available f r o m t h e a u t h o r s ) differ f r o m t h e lasts a m p l e f a c t o r s b e c a u s e t h e y are b a s e d o n t h e
average p r o d u c t i o n o n all s a m p l e d a y s r a t h e r
t h a n j u s t t h e last-sample day. In t h e 1st m o , t h e
sets o f f a c t o r s d i f f e r e d l i t t l e b e c a u s e t h e y b o t h
u s e d t h e s a m e i n f o r m a t i o n , h u t as t h e l a c t a t i o n
progressed they became different. Last-sample
f a c t o r s first decrease, t h e n increase, w h e r e a s t h e
c u m u l a t i v e f a c t o r s g e n e r a l l y decrease.
T h e f a c t o r s will e n a b l e g o a t d a i r y m e n t o
c o m p a r e fairly r e c o r d s o f goats at all stages o f
TABLE 3. Last-sample day factors a for fat records of goat breeds other than Nubian.
8 to 19 mo b
Herd
yield
< 726 kg
726 kg
20 to 31 mo b
32 to 55 mo b
56 m o b
Day at
end of
stage
Nov
to
Mar c
Apr
to
OctC
Nov
to
Mar c
Apr
to
Oct c
Nov
to
Mar c
Apr
to
Oct c
Nov
to
Mar c
Apr
to
Oct c
15
25
35
55
95
135
165
195
215
235
255
275
305
.71
.60
.60
.68
.68
.75
.60
.64
.62
.58
.59
.60
.63
.64
.60
.62
.64
.71
.74
.74
.75
.76
.78
.83
.82
.55
.56
.57
.58
.59
.62
.64
.67
.68
.73
.78
.75
.68
.57
.57
.54
.61
.63
.67
.72
.73
.73
.73
.73
.76
.79
.55
.56
.60
.60
.62
.63
.72
.72
.45
.51
.54
.56
.57
.58
.65
.65
.72
.71
.79
.82
.77
.64
.73
.75
.89
.70
.47
.54
.50
.50
.50
.54
.59
.61
.65
.67
.82
.82
.76
15
25
35
55
95
135
165
195
215
235
255
275
305
.71
.71
.67
.67
.67
.67
.69
.76
.77
.77
.83
.84
.86
.87
.81
.68
.68
.68
.68
.69
.72
.77
.79
.80
.81
.80
.80
.80
.77
.62
.83
.63
.86
.66
.87
.88
.90
.93
.76
.81
.82
.75
.91
.90
.83
.83
.82
.84
.87
.89
.92
.92
.82
.82
.73
.72
.71
.77
.77
.77
.77
.78
.79
.84
.84
.91
.87
.82
.74
.74
.74
.76
.81
.83
.83
.84
.84
.83
.81
.66
.66
.66
.65
.65
.66
.73
.73
.74
.76
.79
.82
.82
.82
.65
.64
.64
.67
.68
.73
.75
.76
.77
.73
.72
.72
.64
.64
.60
.60
.60
.66
.67
.69
.70
.72
.77
.87
.82
aEstirnated 305-day yields = part yield + Factor • (last-sample day yield) • (305 - length of part record).
bAge at kidding.
CMonth of kidding.
Journal of Dairy Science Vol. 62, No. 5, 1979
TECHNICAL NOTE
801
TABLE 4. Last-sample day factorsa for Nubian fat records.
8 to 19 mob
Herd
yield
< 726kg
726 kg
Day at
end of
stage
20 to 31 mo b
56mo b
32 to 55 mo b
Nov
to
Mar c
Apr
to
Oct c
Nov
to
Mar c
Apr
to
Oct c
Nov
to
Mar c
Apr
to
OctC
Nov
to
Mar c
Apr
to
OctC
15
.67
.48
.65
.65
.59
.62
.47
.53
25
35
55
95
135
165
195
215
235
255
275
305
.75
.76
.82
.83
.80
.76
.74
.72
.71
.81
.85
.86
.48
.49
.49
.50
.51
.53
,57
.61
.65
.67
.68
.70
,65
.65
.63
.63
,63
.62
.63
.66
.7t
.76
.87
.86
.62
,59
.60
.61
.63
.65
.66
.67
.73
.76
.88
.85
.52
.56
.61
.63
.68
,68
,68
.62
.60
.60
.60
.62
.62
.62
.59
.59
.60
.71
.71
.71
.71
.72
.72
.73
,50
.51
.52
.54
.58
,58
,58
.58
.58
.58
.58
.58
,50
.50
.47
.48
.48
.48
.48
.50
.50
.53
,57
.59
15
25
35
55
95
135
165
195
215
235
255
275
305
.85
.83
.82
,78
.77
,77
.79
.80
.80
.80
.80
,79
.77
.75
.73
.71
.69
.69
.69
.60
,60
.65
.69
.78
.75
.75
.74
.71
.74
.76
.81
.81
.81
.81
.81
.83
.68
.74
.74
.74
.74
.74
.74
.74
.74
.72
.68
.64
.65
.69
.67
.68
.69
.69
.69
.69
.70
.70
.70
.70
.70
.70
.70
.62
.60
.60
.60
.58
.58
.58
.54
.52
.50
.49
.66
.69
.65
.64
.63
.62
.62
.62
.63
.64
.64
.65
.66
.68
.70
,43
.45
.50
.50
.50
.49
.47
.43
.49
.52
.62
.65
.65
.74
.70
aEstimated 305-day yields = part yield + Factor • (last-sample day yield) • (305 - length of part record).
bAge at kidding.
CMonth of kidding.
l a c t a t i o n . T h e s e e x t e n d e d r e c o r d s wilt enable
m o r e a c c u r a t e culling and b r e e d i n g decisions
a n d are a first step t o w a r d s g e n e t i c evaluations
o f goats. As a d d i t i o n a l goat r e c o r d s b e c o m e
available, t h e s e f a c t o r s s h o u l d b e r e e v a l u a t e d
b e c a u s e t h e y are b a s e d on l i m i t e d data. T h e
large variation in t h e n u m b e r o f days in milk
r e d u c e s t h e a c c u r a c y o f t h e factors. As dairy
goat operations become more commercial,
m o r e u n i f o r m i t y in t h e length o f l a c t a t i o n
would be expected; thus, more accurate factors
s h o u l d be possible. If yields i m p r o v e , a goal
t h a t this w o r k s h o u l d facilitate, t h e 726 kg
value w h i c h s e p a r a t e s h e r d s will b e c o m e obsolete, a n d accuracy p r o b a b l y w o u l d be i m p r o v e d
b y raising this a m o u n t a n d c o m p u t i n g n e w
factors.
ACKNOWLEDGMENTS
This s t u d y was c o n d u c t e d t h r o u g h a c o o p e r a tive a g r e e m e n t b e t w e e n t h e D e p a r t m e n t o f
A n i m a l Science, Cornell University, a n d t h e
Animal Improvement Programs Laboratory,
USDA. T h e A m e r i c a n Dairy G o a t Association and the American Goat Society contributed
t o s u p p o r t o f this p r o j e c t .
REFERENCES
1 Steine, T. A. 1975. Test day records and part
lactations in goat. Meld. Nor. Landbrukshoegsk.
54(31):21.
2 Wiggans, G. R,, and L. D. Van Vleck. 1978. Extending partial lactation milk and fat records with
a function of last-sample production. J. Dairy
Sci. 62:316.
Journal of Dairy Science Vol, 62, No. 5, 1979