Singh
Table 1. Estimated lactation curve parameters of different functions
Parameters
S.No.
Lactation curve functions
a
b
c
d
e
1.
GF
7.28
0.69
0.23
-
-
2.
EF
10.78
-8.36
-0.73
-
-
3.
MLF
15.42
-9.60
7.98
-
-
4.
PRF
2.79
3.24
-0.13
-0.52
-3.73
Table 2. Different lactation curve functions with parameters for prediction of MTDMYs
S. No.
Function
Parameters of function
R 2 (%)
RMSE (kg)
1.
GF
Y t = 7.28 t 0.69 e -0.23t
96.42
0.077
2.
EF
Y t = 10.78 - 8.36 e -0.70t - 0.73t
98.65
0.049
3.
MLF
Y t = 15.42 - 9.60 t 0.5 + 7.98 log(t)
98.48
0.052
4.
PRF
Y t = 2.79 + 3.24 (t/305) - 0.13 (t/305) 2 -0.52 log (305/t) – 3.73 log (305/t) 2
99.86
0.015
Table 3. Predicted MTDMYs (kg) and error of different lactation curve functions
MTDMY
Test
PRF
Prediction
Prediction
Prediction
Prediction
(Least Squares
MLF
EF
GF
Day
Error
Error
Error
Error
Mean)
TD 1
5.91
5.90
-0.004
5.81
-0.09
5.88
-0.02
5.75
-0.15
TD 2
7.29
7.31
0.02
7.37
0.08
7.24
-0.04
7.36
0.07
TD 3
7.41
7.38
-0.02
7.55
0.14
7.54
0.13
7.72
0.31
TD 4
7.20
7.16
-0.03
7.28
0.08
7.32
0.12
7.45
0.25
TD 5
6.82
6.81
-0.007
6.79
-0.02
6.84
0.02
6.88
0.06
TD 6
6.22
6.34
0.12
6.20
-0.01
6.23
0.01
6.18
-0.03
TD 7
5.82
5.76
-0.05
5.54
-0.27
5.55
-0.26
5.43
-0.38
TD 8
5.09
5.03
-0.05
4.85
-0.23
4.85
-0.23
4.71
-0.37
TD 9
4.15
4.16
0.01
4.15
0.001
4.13
-0.01
4.05
-0.09
TD 10
3.11
3.12
0.01
3.43
0.32
3.40
0.29
3.44
0.33
MATERIALS AND METHODS
around 2°C during the winter months, whereas the highest
temperature goes upto 45°C during summer. The annual
Data Collection
rainfall is about 760 to 960mm, out of which most of the
The lactation records used in this study included 9071
rainfall is received during July and August. For the present
monthly test-day milk yield (MTDMY) from 965 Murrah
investigation only those records of Murrah buffaloes were
buffaloes calved during 1977 to 2012 at the ICAR-
considered that had produced minimum of 500 kg for at
National Dairy Research Institute, Karnal. Data was
least 100 days of lactation length. Culling in the middle
collected from the history cum-pedigree sheets and daily
of lactation, abortion, stillbirth or any other pathological
milk yield recording registers maintained at Dairy Cattle
causes which affected the lactation yield were considered
and Breeding Division of this institute. The climate of
asabnormalitiesandthus,suchrecordswerenotconsidered
the farm is subtropical in nature with lowest temperature
for analysis. To ensure the normal distribution of data, the
190
Journal of Animal Research: v.5 n.1. April 2015