Agriculture Reference
In-Depth Information
An 'ideal' parity distribution is essential to maintain consistent production performance
and to avoid severe fluctuations in the number of replacement gilts. However, it is difficult
to establish an 'ideal' or 'standard' parity distribution (Dial
et al.
, 1992) because it varies
from farm to farm as it depends on certain farm characteristics such as the breed, cost
of replacement, type of facilities, and husbandry skills (D'Allaire
et al.
, 2012). Table 19.1
presents the ideal parity distribution of a sow herd as reported by several researchers. To
achieve these targets, it is necessary to limit the culling of younger females from the herd
regardless of removal or culling reason.
19.3.2
Productivity
Reproducing females are the most valuable animals in the herd (Schenck
et al.,
2008)
and it is estimated that 40 to 50% of sows are culled before their third parity (Boyle
et
al.,
1998; D'Allaire
et al.,
1987; Jørgensen, 2000a) a time at which initial replacement
costs have not been met (Stalder
et al.
, 2003). Sow replacement decisions influence
the expected lifetime of sows, the annual replacement rate and production costs. For
example, severely lame sows must be euthanized, which implies a loss of slaughter
revenue and extra cost for euthanasia and/or destruction of the carcass (Pluym
et al.
,
2011). In countries like Denmark, it is a criminal offence to send a lame sow for slaughter
leading to an increase in on-farm mortality of sows due to euthanasia and increasing
veterinary costs (Boyle
et al.
, 2012). It is likely that in the future, other countries in the
European Union will also implement similar legislation which could have huge financial
implications for pig producers.
Additionally, a producer will incur further expenses associated with developing and
acclimating replacement gilts (Stalder
et al.
, 2000). Faust
et al.
(1992, 1993) developed
bioeconomic simulation models of a hierarchical pig breeding system to determine the
effects of various traits on profitability, including culling. The results demonstrated that
pig breeding systems with the lowest replacement rates were most profitable. They also
found that at low replacement rates, gilts were worth as much as 450% of market value;
however, at high replacement rates, the value of replacement gilts was no more than 175%
Table 19.1. Recommended parity distribution (expressed in percentage of sows/parity) from several published
articles.
Parity
0
1
2
3
4
5
6
7
8
Straw (1984)
20
18
17
16
15
14
-
-
-
Parson
et al.
(1990)
30
23
19
14
10
5
2
1
-
Muirhead and Alexander (1997)
17
15
14
13
12
11
10
5
3
Carroll (1999)
-
17
16
15
14
13
11
10
4
Morrison
et al.
(2002)
19.1
16.5
16.9
14.1
10.2
8.2
5.1
4.9
4.9
Pinilla and Lecznieski (2014)
20
17
16
15
14
13
5
-
-
