216 T
. Lucia et al. Livestock Production Science 63 2000 213 –222
effect of the kth entry month; and e is the random
Females classified in the ‘miscellaneous’ category
ijkn
error. Differences in lifetime productivity across corresponded to 13.3 of all removals, but 788 of
categories of removal reasons were tested using the these females 74.2 did not have a recorded
Fisher’s protected least significant difference test. reason for culling. Among those females having
Even though the effect of interaction between the known culling reasons, 132 were unthrifty, 56 had
herd and removal reason was initially included in the behavioural problems, 44 were transferred out of the
model, this effect was excluded from the final model herd due to market reasons, and 42 had removal
due to lack of statistical significance. All analyses of reasons inconsistent with their biological data or that
variance were conducted through the General Linear occurred in a proportion too small to be reported
Models procedure of SAS 1988.
alone. Almost 9 of all females had no reason for culling other than old age Table 1.
Nearly 19 of the removals occurred for parity-
3. Results zero females, while almost 15 occurred for females
removed at parity one Table 1. Among the parity- Among all females having a recorded removal
zero females, nearly 65 were culled for ‘reproduc- event, 92.6 were culled and 7.4 were removed
tion’ and 14 were culled for ‘locomotion’ problems due to death Table 1. Females having an unknown
Fig. 1. For females having one parity at removal, or unrecorded reason for removal corresponded to
reproductive reasons and locomotion disorders ac- 13.5 of the total, including 285 records in the
counted for 43 and 18 of the removals, respec- ‘death’ category, and 788 records for culled females
tively. Litter performance was the most common classified in the ‘miscellaneous category’. Thus, only
removal reason for females having four to six 51.8 of the females in the ‘death’ category had a
parities, whereas old age was the most common recorded reason for death.
reason for removal among females having more than Culls attributed to ‘reproduction’ accounted for the
seven parities. largest proportion of removals 33.6 across
Mean herd life for all females was 582.7 herd categories Table 1. Nearly 36 of the reproduc-
days. Females removed at parity zero spent, on tion-related culls occurred for parity-zero females.
average, 119.9 days in the breeding herd. Mean herd Conception failure was the most common reason for
life for females removed at parity one or higher was reproductive culling, followed by failure to farrow
668 days, and was 691 days when estimated on a per and lack of observed oestrus Table 2. Culls for
mated female basis Table 3. Mean parity at remov- litter performance accounted for 20.6 of all remov-
al for all females was 3.3. The proportion of lifetime als Table 1. Locomotion problems represented 13
NPD for all females was 36.4, and was 25 when of all removals Table 1; nearly 55 of such culls
estimated on a per mated female basis. Without were among females having 0–2 parities at removal.
considering females removed at parity zero having
Table 1 Frequency of removal reasons by parity at removal
a
Reason Parity at removal
n 1
2 3
4 5–6
7–8 91
Reproduction 35.9
19.3 11.5
9.8 8.0
10.7 3.8
1.0 2680
33.6 Litter performance
– 10.5
13.9 14.7
17.1 25.1
13.9 4.7
1644 20.6
Miscellaneous 18.5
15.9 13.0
13.4 12.6
17.4 7.4
1.8 1062
13.3 Locomotion
20.4 19.8
15.0 13.5
10.2 14.0
5.6 1.5
1054 13.2
Old age 0.4
0.1 0.4
1.3 2.9
23.5 43.4
28.0 694
8.7 Death
14.2 14.1
16.1 14.4
13.6 17.5
7.5 2.7
590 7.4
Disease peripartum 12.9
15.3 13.7
10.8 14.9
22.5 6.4
3.6 249
3.1 Total
18.7 14.9
12.1 11.4
10.9 17.0
10.4 4.5
7973 100.0
a
Frequencies in cells add to 100 for each category of removal reason.
T . Lucia et al. Livestock Production Science 63 2000 213 –222
217 Table 2
Reasons for removal within categories of culling reasons
a b
Reason Records
Frequency Proportion of total
Reproduction Conception failure
1065 39.7
13.4 Failure to farrow
892 33.3
11.2 Lack of observed heat
723 27.0
9.1 Total
2680 100.0
33.6 Litter performance
Farrowing productivity 1121
68.2 14.1
Lactation–weaning productivity 393
23.9 4.9
Difficult farrowing 130
7.9 1.6
Total 1644
100.0 20.6
Locomotion Lameness
533 50.6
6.7 Unsoundness
231 21.9
2.9 Injury
206 19.5
2.6 Downer syndrome
84 7.9
1.1 Total
1054 100.0
13.2 Disease peripartum problems
Prolapse 88
35.3 1.1
Vulvar discharge 25
10.0 0.3
Multiple systems 22
8.8 0.3
Gastrointestinal 21
8.4 0.3
Respiratory 18
7.2 0.2
Ulcer 18
7.2 0.2
Urogenital 17
6.8 0.2
Central nervous 16
6.4 0.2
Metritis 15
6.0 0.2
c
Other 9
3.6 0.1
Total 249
100.0 3.1
a
Frequency within category.
b
Frequency considering all removals n 57973.
c
Includes abscess, cardiovascular conditions and skin-cutaneous conditions.
spent the entire herd life in non-productive ac- culled for reproduction accumulated the largest
tivities, mean lifetime NPD was between 18 and proportion of lifetime NPD across categories P ,
21.6 Table 3. 0.01.
Parity number was higher and herd life was longer Average pig output accumulated during herd life
for females culled for Old age P ,0.01 than for was 45 pigs born, 41.3 pigs born alive and 35.9 pigs
those having removals attributed to other reasons weaned Table 3. Mean lifetime pig output per litter
Table 4. However, the proportion of lifetime NPD weaned was 10.7 pigs born, 9.8 pigs born alive and
for females culled either for old age or for litter 8.7 pigs weaned. Generally, females culled for old
performance did not differ P .0.01. Females culled age produced the largest pig output both cumulative
for reproduction and locomotion disorders achieved and per litter weaned across categories of removal
shorter herd life and fewer parities than those reasons Tables 5 and 6. In contrast, females culled
removed for other reasons P ,0.01. Mean herd life for either reproduction or locomotion disorders pro-
did not differ between those two categories P . duced the lowest cumulative pig output P ,0.01,
0.05, but mean parity at removal was higher for whereas females culled for litter performance pro-
females culled for locomotion problems than for duced the lowest pig output per litter weaned P ,
those culled for reproduction P ,0.01. Females 0.05.
218 T
. Lucia et al. Livestock Production Science 63 2000 213 –222
Fig. 1. Reason-specific proportions of removal by parity at removal.
Females having herd life at least one year long removed for reproductive failure. NPD accumulation
produced 2.16 to 2.23 litters and nearly 19 weaned is negatively associated with annual reproductive
pigs, and wasted 60 to 70 NPD per each year spent efficiency measured by the number of pigs weaned
in the breeding herd Table 3. Annual productivity per female per year, as already characterised at the
was highest for females culled for old age Table 7 herd level Wilson et al., 1986; Polson et al., 1990;
and lowest for those culled for reproductive failure Dial et al., 1992. When measured over herd life, the
P ,0.05. negative association between NPD and female re-
productive efficiency is better characterised when NPD are expressed as proportions of herd life wasted
4. Discussion in non-productive activities rather than by cumula-
