(a)
(b)
Figure 1. The effect of (a) herd and (b) calving year on interval traits for calving date to first
service date (CFS) and days open (DO)
specific strategies to maintain a DO interval of
about 147 days.
Subsequently, another data set was compiled
using a commercial (DIMSSA) reproduction
management programme. Reproduction
records of about 45 560 lactations from 15
770 Holstein cows were obtained from 27
dairy herds. Fertility traits for heifers and
similar fertility traits for cows as above, were
derived. Herds were ranked using a ranking
system for each trait, 1 being best and 27
poorest. The top and bottom three herds were
subsequently identified. In Table 2 the mean
reproduction management performance for
all Holstein herds and the top and bottom 10%
of herds are shown.
Table 2. The mean reproduction management performance for 27 herds in comparison to
the top and bottom 10% of all Holstein herds
All
Bottom
Animals
Parameters
herds
Top 10%
10%
Heifers
Age at first service (m)
17.7
14.5
23.8
First service before 15m of age (%)
30
68
0
First service before 18m of age (%)
61
89
7
Age at first calving (AFC) (m)
27.8
24.6
33.4
AFC before 24 m of age (%)
21
60
1
AFC before 27 m of age (%)
50
84
8
Cows
Interval calving to first AI (d)
92
89
104
First service before 80 days-in-milk (%)
51
62
44
Services per conception
2.16
1.62
2.35
Interval days open (d)
140
112
164
Pregnant before 100 days-in-milk (%)
40
57
31
Pregnant before 200 days-in-milk (%)
81
90
72
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