Trop Anim Health Prod DOI 10.1007/s11250-014-0554-0
REGULAR ARTICLES
Sow removal in a commercial pig herd in Zimbabwe Lawrence Masaka & Marvelous Sungirai & Casper Nyamukanza & Chido Bhondai
Accepted: 4 February 2014 # Springer Science+Business Media Dordrecht 2014
Abstract A study was carried out at a 2,200 sow farrowfinisher facility in Zimbabwe to determine the main reasons for sow removal and the season when removal was most common. Data on the number of sows culled and the reasons for culling as well as mortalities was recorded weekly for a 12month period. The culling frequency was 52.8 % (n=1 162). Descriptive statistics indicated that reproductive problems accounted for 70.8 % (n = 823) of sow removals, death (15.6 %, n=181), lameness (4.6 %, n=53), miscellaneous (2.5 %, n = 29), production (2.2 %, n = 26), peripartum (2.2 %, n=25) and age (2.2 %, n=25). The results also showed that culling was highest in gilts and primiparous sows (41.3 %, n=480) with the least culling being observed in sows in parity 7 (5.3 %, n=61). The hot wet season was observed to be the one when culling was most common (33.5 %, n=389) with the least being in the cold dry season (17 %, n=198). It was concluded that most of the sow removal was unplanned. There is a need to improve replacement gilt selection, reproductive efficiency, health and nutrition management to increase productivity in a sow unit.
major reasons are associated with reproductive problems, lameness as well as low levels of productivity (Engblom 2008; Mote et al. 2009; Segura-Correa et al. 2011). The contribution of each of these reasons is, however, variable depending on herd, region and management practices. Management decisions govern the implementation of sound culling policies which in turn give more control to pig farmers over which animals can stay in the herd and which ones will be culled (Sasaki and Koketsu 2012). Failure to have such guidelines will result in an increase in unplanned culling. Research on sow culling in Zimbabwe has been limited to research farms such that extrapolation of these findings to culling practices on commercial farms is constrained by major differences in management practices (Dhliwayo 2007). The aim of this research is to give a description of culling reasons and how they are distributed on a typical commercial sow unit in Zimbabwe. Emphasis will also be directed on the potential influence of season on the distribution of the culling reasons.
Keywords Culling . Parity . Season . Reproduction . Tropics . Death
Materials and methods
Introduction Sow culling is an invaluable practice in commercial pig production as it ensures acceptable production levels within the sow herd. The reasons for culling in a commercial sow herd have been well documented, and there is a consensus that the L. Masaka (*) : M. Sungirai : C. Nyamukanza : C. Bhondai Department of Livestock and Wildlife Management, Midlands State University, P. Bag 9055, Gweru, Zimbabwe e-mail: [email protected]
The research was carried out at Triple C Pigs, a commercial pig farm in Norton near Harare. The farm is located at a latitude of 17° 57″ S: 30° 38″ E and at an altitude of about 1,360 m above sea level. Temperatures in the region range from 2 to 33 °C, and the farm receives a mean annual rainfall of about 650 mm. The study was undertaken over a 12-month period on a mature commercial 2,200 sow (Large White×Landrace) farrow-to-finish facility. Each sow house accommodated 400 sows and one boar to help in heat detection and finding returns. Artificial insemination was used entirely in the herd. Replacement sows were obtained from Topigs (South Africa), and gilts were replaced by F1 gilts with a minimum of 14 functional teats that were bred on the farm.
Trop Anim Health Prod
Data was collected from sow record books and sow cards for the period under study. The following information was collected: sow tag number, date of culling and culling reason. A list of 22 reasons for culling was identified, and these were grouped into seven main categories (see Table 1). Gilts, designated parity 0, were included in the analysis from 30 weeks of age when they had their first service. Sows with a parity number of 9 or higher were grouped together in the statistical analysis due to their low numbers. The final data set comprised of 1,162 sow records. Descriptive statistics using cross tabulations for removal reasons across all parities under study were obtained using Genstat Discovery Fourth Edition Software (2012).
highest contribution to culling by lameness was made in the cold dry season. The hot dry and hot wet seasons accounted for approximately 64 % of the sows that died with each season contributing approximately 50 % to this frequency (see Fig 1). Death was ranked second in importance as a reason for sow removal in all seasons (see Fig 2). The highest frequency of removal of sows due to peripartum problems was in the cold dry season followed by the warm wet, hot dry and hot wet season. Peripartum problems were least prevalent in sows culled during the hot wet season and most frequent in sows culled during the cold dry season. Culling due to age was most common in the warm wet season and least frequent in the cold dry season (see Fig 2).
Results
Discussion
The culling rate for the period under study was approximately 45 % excluding gilts/sows that died due to disease or any other reason. The largest contribution to culling was made by reproductive reasons followed by death, lameness, miscellaneous, production, peripartum problems and age (see Table 2). In all parities, reproduction was the most important reason for culling (see Table 3). Among the specific reasons for culling under reproductive reasons, anoestrous and repeated returns were the most common reasons for culling (see Table 4). Of all the sows removed for reproductive reasons, approximately 45 % were gilts and primiparous sows. Culling due to reproductive reasons was most frequent in the hot wet season and least frequent in the cold dry season (see Fig 1). The results show a progressive decline in the culling frequency from the hot wet to the cold dry season and an increase in the hot dry season. Reproductive reasons were the most important reason for culling in all seasons accounting for over 60 % of the culling frequency in each of the seasons (see Fig 2).Culling due to lameness was most frequent in the hot dry season and least frequent in the warm wet season. Among the sow totals culled per season, the
The culling rate observed in this study falls within the range observed in modern commercial pig production in different parts of the world of 10–50 % (Lucia Jr et al. 2000; Engblom et al. 2007; Mote et al. 2009). Reproductive failure as the main reason for culling is consistent with other studies (Dagorn and Aumaitre 1979; Stein et al. 1990; Dhliwayo 2007; Engblom et al. 2007; Engblom et al. 2008b; Mote et al. 2009; SeguraCorrea et al. 2011); however, the frequency of culling due to reproductive reasons in the present study (70.8 %) was much higher than reported in other studies; 26.9 % (Segura-Correa et al. 2011), 16.4 % (Dhliwayo 2007), 35.1 % (Mote et al. 2009) and 27 % (Engblom et al. 2007). This may suggest management shortcomings particularly estrous detection and nutrition in young sows as they constitute over 50 % of the total number culled due to reproductive reasons. Culling due to reproductive reasons was most frequent in early parities (0– 2) accounting for 52.2 % of the total culled due to reproductive reasons. This is in agreement with Dhliwayo (2007) who observed a culling frequency of 58 % for the same parities. Culling frequencies due to reproductive reasons were higher during the hot wet and warm wet seasons and declined towards the hot dry season. This can be attributed to seasonal infertility (Auvigne et al. 2010). A similar reduction in reproductive performance during summer has been reported by other authors (Tummaruk et al. 2000; Tummaruk et al. 2004; Gourdine et al. 2006; Bertoldo et al. 2012). Within the reproductive reasons, anoestrous was the major reason for removal, and this is consistent with the findings of Segura-Correa et al. (2011) who reported a frequency of removal due to anoestrous of 34.2 % and Koketsu et al. (1997) who observed a frequency of 25.2 % within reproductive reasons for culling. Other authors have reported returns to estrous as the most frequent form of reproductive failure (Engblom et al. 2007; Vargas et al. 2009). The differences in the importance of the reasons behind reproductive failure (anoestrous and repeated returns) on different farms have been
Table 1 Classification of culling reasons Culling reason
Components
Reproduction
Anoestrous, repeated returns, discharge, empty, excess service, abortion Dog sitter, bad legs Litter size 7 %. In his review, Fekete (1999) noted that environmental influences, immunological factors and nutritional allergies can combine to increase the risk of abortion in
a sow unit if management is not wary of these factors. Since there is no evidence to suggest infectious causes of abortion, it is likely that abortion risk was increased due to failure to eliminate predisposing factors from the environment. Sow death constituted the second most important reason for culling within the herd. Typical mortality in sow units ranges between 3 and 9 % (Christensen et al. 1995; Karg and Bilkei 2002; Dhliwayo 2007; Mote et al. 2008; Sasaki and Koketsu 2008; Mondal et al. 2012). Mortalities higher than 5 % are considered to be unacceptable (Abiven et al. 1998). The current study revealed that 15.6 % of all sows culled were those that died. This mortality frequency is similar to that seen in sows reared in an outdoor system (Karg and Bilkei 2002). Out of all sows that died the highest frequency was for sows in parities ≥9 followed by first parity sows and gilts. This is in agreement with the assertion that the risk for mortality is highest in older parity sows and gilts as well as peripartum females (Sanz et al. 2007, Engblom et al. 2008b). Most sows died in the hot wet and hot dry seasons which correspond to summer, and this agrees with results from other studies (D’Allaire et al. 1991; Deen et al. 2000; Koketsu 2000).
Table 3 Frequency (%) of gilt/sow removal by parity Parity at removala Reason Reproduction Lameness Death Peripartum problems Age Production Miscellaneous n Total% a
0 83.8 2.0 8.3 0.3 0.0 0.7 5.0 302 30.0
1 68.0 7.3 15.7 2.3 0.0 3.9 2.8 178 15.3
2 62.9 6.7 23.6 3.4 0.0 2.3 1.1 89 7.7
Cell frequencies for each removal parity add up to 100
3 78.5 0.0 12.3 4.6 0.0 4.6 0.0 65 5.6
4 71.6 0.0 20.9 3.0 0.0 4.5 0.0 67 5.8
5 68.8 1.6 21.9 4.7 0.0 1.6 1.6 64 5.5
6 62.3 5.8 30.4 0.0 0.0 0.0 1.5 69 5.9
7 70.5 4.9 18.0 0.0 1.6 4.9 0.0 61 5.3
8 72.7 6.5 14.3 1.3 3.9 1.3 0.0 77 6.6
≥9 56.8 7.9 14.7 4.2 11.1 2.1 3.2 190 16.4
Number 823 53 181 25 25 26 29 1162
Total (%) 70.8 4.6 15.6 2.2 2.2 2.2 2.5
Trop Anim Health Prod Table 4 Breakdown of culling reasons given as number of gilts/ sows within each specific reason, frequencies within each culling reason and as a percentage of the total gilts/sow culled
Specific reason
Number (frequency (%) and percent of the total)
Reproduction Abortion Anoestrous Vaginal discharge Empty Excess service Repeated returns Total Lameness Dog sitter
171 (20.8, 14.7) 244 (29.7, 21.0) 48 (5.8, 4.1) 41 (5.0, 3.5) 133 (16.2, 11.5) 186 (22.6, 16.0) 823 (100, 70.8) 11 (20.8, 1.0)
Bad legs Total Death Age
42 (79.3, 3.6) 53 (100, 4.6) 181 (100, 15.6) 25 (100, 2.2)
Culling frequencies due to lameness exhibit a rather wide range from 8 to 27 % (Friendship et al. 1986; D’Allaire et al. 1991; Lucia Jr et al. 2000; Dhliwayo 2007; Engblom et al. 2007; Segura-Correa et al. 2011). The reason for this wide range of frequencies could be that some authors exclude sows that are euthanized due to locomotor problems from the total culled due to this reason, while others opt to include sows euthanized under this group. Euthanasia due to lameness has been observed to be one of the top reasons for sow mortality in commercial herds (D’Allaire et al. 1991; Sanz et al. 2007; Engblom et al. 2008a). This might explain why in the current study sow mortality is high while culling due to lameness is low. The frequency of culling due to lameness was high for the
Specific reason
Peripartum problems Bad udders Dead piglets Multiple abscesses Multiple mummies Still births Total Production Miscellaneous Dystocia Emergence Sickness Savaging Selection Total
Number (frequency (%) and percent of the total)
4 (16.0, 0.3) 3 (12.0, 0.3) 1 (4.0, 0.1) 6 (24.0, 0.5) 11 (44.0, 1.0) 25 (100, 2.2) 26 (100, 2.2) 5 (17.2, 0.4) 4 (13.8, 0.3) 8 (27.6, 0.7) 2 (6.9, 0.2) 10 (34.5, 0.9) 29 (100, 2.5)
lower parities (0–2) agreeing with other findings (Friendship et al. 1986; Engblom et al. 2007; Mote et al. 2009). However, the current study also showed a high frequency of removal due to lameness in sows in parities ≥9 which is contrary to work showing that the risk of lameness decreases as parity increases (Lucia Jr et al. 2000; Segura-Correa et al. 2011). This is likely due to poor selection for structural soundness when sows are still in lower parities. Failure to select for structural soundness in early parities will increase the likelihood of sows suffering from bad legs, i.e. footrot, overgrown claws and torn dewclaws, when they reach older parities (Dewey et al. 1992, Dewey et al. 1993). Culling due to lameness was more frequent during the cold dry season which
100
Fig. 1 Frequency of culling by reason within the individual seasons
90
Culling frequency (%)
80 70 60 50
Seasons
40
Hot dry
30
Cold dry Warm wet
20
Hot wet
10 0
Culling reasons
Trop Anim Health Prod 100
Fig. 2 Contribution of culling reasons within each season
90
Culling frequency (%)
80 Culling reasons 70
Miscellaneous
60
Performance
50
Age
40
Peripartum problems Death
30
Lameness 20
Reproduction
10 0 Hot wet
is in agreement with the findings of Friendship et al. (1986) who reported a higher frequency of culling due to locomotor problems in winter. For peripartum problems, culling frequencies range between 2 and 36 % (Engblom 2008). Parities at greatest risk of culling due to peripartum problems are parities 1, 5 and 8 (D’Allaire et al. 1991), while other workers concluded that the risk was highest in the first parity (Engblom 2008). The current study agreed with these findings with regards to the frequency being high in first parity, but we also found that the highest frequency was for sows in parities ≥9. The specific reasons contributing the most to culling due to peripartum reasons were stillbirths and multiple mummies. Literature has clarified that older parities are more prone to both still births and multiple mummies (Borges et al. 2005; Segura-Correa and Solorio-Rivera 2013). Peripartum problems were more frequent in the cold dry season compared to all other seasons. This is in contradiction with work showing that the major components of peripartum problems (multiple mummification and stillbirths) have higher frequencies in summer (Phongphaewa et al. 2001). There is evidence suggesting that seasonal infertility increases late pregnancy losses in pigs (Bertoldo et al. 2009). Only sows in parities 7, 8 and ≥9 were culled due to age, and it was third in importance for parities ≥9. This is in agreement with other authors who reported an increase in culling frequency due to age as parity increased (D’Allaire et al. 1991; Lucia Jr et al. 2000; Segura-Correa et al. 2011). However, these authors also reported culling due to age in lower parities. The difference with this study is due to differences in the allocation of culling reasons where removals due to age were influenced by other factors such as keeping younger sows that have failed to reproduce indefinitely and eventually culling them due to age and not reproductive failure. The higher frequencies of culling due to age reported in literature compared to the current study can be explained by
Warm wet Cold dry Season
Hot dry
the overlap between culling due to age and productivity (Dhliwayo 2007, Segura-Correa et al. 2011) as well as inclusion of other factors within the age classification such as overweight sows in lower parities (D’Allaire et al. 1991). The fact that culling due to age was more frequent in the warm wet season is not indicative of a relationship between that season and culling frequency, since culling due to age is part of planned culling; this observation is merely a reflection of the management’s decision to cull most of the older sows during that season. Culling due to low productivity had a frequency that was much lower (2.2 %) than that reported in literature which has a range of 7–37 % (D’Allaire et al. 1991; Dhliwayo 2007; Mote et al. 2009; Segura-Correa et al. 2011). In the current study, low productivity was defined only as sows producing low litter sizes (
REGULAR ARTICLES
Sow removal in a commercial pig herd in Zimbabwe Lawrence Masaka & Marvelous Sungirai & Casper Nyamukanza & Chido Bhondai
Accepted: 4 February 2014 # Springer Science+Business Media Dordrecht 2014
Abstract A study was carried out at a 2,200 sow farrowfinisher facility in Zimbabwe to determine the main reasons for sow removal and the season when removal was most common. Data on the number of sows culled and the reasons for culling as well as mortalities was recorded weekly for a 12month period. The culling frequency was 52.8 % (n=1 162). Descriptive statistics indicated that reproductive problems accounted for 70.8 % (n = 823) of sow removals, death (15.6 %, n=181), lameness (4.6 %, n=53), miscellaneous (2.5 %, n = 29), production (2.2 %, n = 26), peripartum (2.2 %, n=25) and age (2.2 %, n=25). The results also showed that culling was highest in gilts and primiparous sows (41.3 %, n=480) with the least culling being observed in sows in parity 7 (5.3 %, n=61). The hot wet season was observed to be the one when culling was most common (33.5 %, n=389) with the least being in the cold dry season (17 %, n=198). It was concluded that most of the sow removal was unplanned. There is a need to improve replacement gilt selection, reproductive efficiency, health and nutrition management to increase productivity in a sow unit.
major reasons are associated with reproductive problems, lameness as well as low levels of productivity (Engblom 2008; Mote et al. 2009; Segura-Correa et al. 2011). The contribution of each of these reasons is, however, variable depending on herd, region and management practices. Management decisions govern the implementation of sound culling policies which in turn give more control to pig farmers over which animals can stay in the herd and which ones will be culled (Sasaki and Koketsu 2012). Failure to have such guidelines will result in an increase in unplanned culling. Research on sow culling in Zimbabwe has been limited to research farms such that extrapolation of these findings to culling practices on commercial farms is constrained by major differences in management practices (Dhliwayo 2007). The aim of this research is to give a description of culling reasons and how they are distributed on a typical commercial sow unit in Zimbabwe. Emphasis will also be directed on the potential influence of season on the distribution of the culling reasons.
Keywords Culling . Parity . Season . Reproduction . Tropics . Death
Materials and methods
Introduction Sow culling is an invaluable practice in commercial pig production as it ensures acceptable production levels within the sow herd. The reasons for culling in a commercial sow herd have been well documented, and there is a consensus that the L. Masaka (*) : M. Sungirai : C. Nyamukanza : C. Bhondai Department of Livestock and Wildlife Management, Midlands State University, P. Bag 9055, Gweru, Zimbabwe e-mail: [email protected]
The research was carried out at Triple C Pigs, a commercial pig farm in Norton near Harare. The farm is located at a latitude of 17° 57″ S: 30° 38″ E and at an altitude of about 1,360 m above sea level. Temperatures in the region range from 2 to 33 °C, and the farm receives a mean annual rainfall of about 650 mm. The study was undertaken over a 12-month period on a mature commercial 2,200 sow (Large White×Landrace) farrow-to-finish facility. Each sow house accommodated 400 sows and one boar to help in heat detection and finding returns. Artificial insemination was used entirely in the herd. Replacement sows were obtained from Topigs (South Africa), and gilts were replaced by F1 gilts with a minimum of 14 functional teats that were bred on the farm.
Trop Anim Health Prod
Data was collected from sow record books and sow cards for the period under study. The following information was collected: sow tag number, date of culling and culling reason. A list of 22 reasons for culling was identified, and these were grouped into seven main categories (see Table 1). Gilts, designated parity 0, were included in the analysis from 30 weeks of age when they had their first service. Sows with a parity number of 9 or higher were grouped together in the statistical analysis due to their low numbers. The final data set comprised of 1,162 sow records. Descriptive statistics using cross tabulations for removal reasons across all parities under study were obtained using Genstat Discovery Fourth Edition Software (2012).
highest contribution to culling by lameness was made in the cold dry season. The hot dry and hot wet seasons accounted for approximately 64 % of the sows that died with each season contributing approximately 50 % to this frequency (see Fig 1). Death was ranked second in importance as a reason for sow removal in all seasons (see Fig 2). The highest frequency of removal of sows due to peripartum problems was in the cold dry season followed by the warm wet, hot dry and hot wet season. Peripartum problems were least prevalent in sows culled during the hot wet season and most frequent in sows culled during the cold dry season. Culling due to age was most common in the warm wet season and least frequent in the cold dry season (see Fig 2).
Results
Discussion
The culling rate for the period under study was approximately 45 % excluding gilts/sows that died due to disease or any other reason. The largest contribution to culling was made by reproductive reasons followed by death, lameness, miscellaneous, production, peripartum problems and age (see Table 2). In all parities, reproduction was the most important reason for culling (see Table 3). Among the specific reasons for culling under reproductive reasons, anoestrous and repeated returns were the most common reasons for culling (see Table 4). Of all the sows removed for reproductive reasons, approximately 45 % were gilts and primiparous sows. Culling due to reproductive reasons was most frequent in the hot wet season and least frequent in the cold dry season (see Fig 1). The results show a progressive decline in the culling frequency from the hot wet to the cold dry season and an increase in the hot dry season. Reproductive reasons were the most important reason for culling in all seasons accounting for over 60 % of the culling frequency in each of the seasons (see Fig 2).Culling due to lameness was most frequent in the hot dry season and least frequent in the warm wet season. Among the sow totals culled per season, the
The culling rate observed in this study falls within the range observed in modern commercial pig production in different parts of the world of 10–50 % (Lucia Jr et al. 2000; Engblom et al. 2007; Mote et al. 2009). Reproductive failure as the main reason for culling is consistent with other studies (Dagorn and Aumaitre 1979; Stein et al. 1990; Dhliwayo 2007; Engblom et al. 2007; Engblom et al. 2008b; Mote et al. 2009; SeguraCorrea et al. 2011); however, the frequency of culling due to reproductive reasons in the present study (70.8 %) was much higher than reported in other studies; 26.9 % (Segura-Correa et al. 2011), 16.4 % (Dhliwayo 2007), 35.1 % (Mote et al. 2009) and 27 % (Engblom et al. 2007). This may suggest management shortcomings particularly estrous detection and nutrition in young sows as they constitute over 50 % of the total number culled due to reproductive reasons. Culling due to reproductive reasons was most frequent in early parities (0– 2) accounting for 52.2 % of the total culled due to reproductive reasons. This is in agreement with Dhliwayo (2007) who observed a culling frequency of 58 % for the same parities. Culling frequencies due to reproductive reasons were higher during the hot wet and warm wet seasons and declined towards the hot dry season. This can be attributed to seasonal infertility (Auvigne et al. 2010). A similar reduction in reproductive performance during summer has been reported by other authors (Tummaruk et al. 2000; Tummaruk et al. 2004; Gourdine et al. 2006; Bertoldo et al. 2012). Within the reproductive reasons, anoestrous was the major reason for removal, and this is consistent with the findings of Segura-Correa et al. (2011) who reported a frequency of removal due to anoestrous of 34.2 % and Koketsu et al. (1997) who observed a frequency of 25.2 % within reproductive reasons for culling. Other authors have reported returns to estrous as the most frequent form of reproductive failure (Engblom et al. 2007; Vargas et al. 2009). The differences in the importance of the reasons behind reproductive failure (anoestrous and repeated returns) on different farms have been
Table 1 Classification of culling reasons Culling reason
Components
Reproduction
Anoestrous, repeated returns, discharge, empty, excess service, abortion Dog sitter, bad legs Litter size 7 %. In his review, Fekete (1999) noted that environmental influences, immunological factors and nutritional allergies can combine to increase the risk of abortion in
a sow unit if management is not wary of these factors. Since there is no evidence to suggest infectious causes of abortion, it is likely that abortion risk was increased due to failure to eliminate predisposing factors from the environment. Sow death constituted the second most important reason for culling within the herd. Typical mortality in sow units ranges between 3 and 9 % (Christensen et al. 1995; Karg and Bilkei 2002; Dhliwayo 2007; Mote et al. 2008; Sasaki and Koketsu 2008; Mondal et al. 2012). Mortalities higher than 5 % are considered to be unacceptable (Abiven et al. 1998). The current study revealed that 15.6 % of all sows culled were those that died. This mortality frequency is similar to that seen in sows reared in an outdoor system (Karg and Bilkei 2002). Out of all sows that died the highest frequency was for sows in parities ≥9 followed by first parity sows and gilts. This is in agreement with the assertion that the risk for mortality is highest in older parity sows and gilts as well as peripartum females (Sanz et al. 2007, Engblom et al. 2008b). Most sows died in the hot wet and hot dry seasons which correspond to summer, and this agrees with results from other studies (D’Allaire et al. 1991; Deen et al. 2000; Koketsu 2000).
Table 3 Frequency (%) of gilt/sow removal by parity Parity at removala Reason Reproduction Lameness Death Peripartum problems Age Production Miscellaneous n Total% a
0 83.8 2.0 8.3 0.3 0.0 0.7 5.0 302 30.0
1 68.0 7.3 15.7 2.3 0.0 3.9 2.8 178 15.3
2 62.9 6.7 23.6 3.4 0.0 2.3 1.1 89 7.7
Cell frequencies for each removal parity add up to 100
3 78.5 0.0 12.3 4.6 0.0 4.6 0.0 65 5.6
4 71.6 0.0 20.9 3.0 0.0 4.5 0.0 67 5.8
5 68.8 1.6 21.9 4.7 0.0 1.6 1.6 64 5.5
6 62.3 5.8 30.4 0.0 0.0 0.0 1.5 69 5.9
7 70.5 4.9 18.0 0.0 1.6 4.9 0.0 61 5.3
8 72.7 6.5 14.3 1.3 3.9 1.3 0.0 77 6.6
≥9 56.8 7.9 14.7 4.2 11.1 2.1 3.2 190 16.4
Number 823 53 181 25 25 26 29 1162
Total (%) 70.8 4.6 15.6 2.2 2.2 2.2 2.5
Trop Anim Health Prod Table 4 Breakdown of culling reasons given as number of gilts/ sows within each specific reason, frequencies within each culling reason and as a percentage of the total gilts/sow culled
Specific reason
Number (frequency (%) and percent of the total)
Reproduction Abortion Anoestrous Vaginal discharge Empty Excess service Repeated returns Total Lameness Dog sitter
171 (20.8, 14.7) 244 (29.7, 21.0) 48 (5.8, 4.1) 41 (5.0, 3.5) 133 (16.2, 11.5) 186 (22.6, 16.0) 823 (100, 70.8) 11 (20.8, 1.0)
Bad legs Total Death Age
42 (79.3, 3.6) 53 (100, 4.6) 181 (100, 15.6) 25 (100, 2.2)
Culling frequencies due to lameness exhibit a rather wide range from 8 to 27 % (Friendship et al. 1986; D’Allaire et al. 1991; Lucia Jr et al. 2000; Dhliwayo 2007; Engblom et al. 2007; Segura-Correa et al. 2011). The reason for this wide range of frequencies could be that some authors exclude sows that are euthanized due to locomotor problems from the total culled due to this reason, while others opt to include sows euthanized under this group. Euthanasia due to lameness has been observed to be one of the top reasons for sow mortality in commercial herds (D’Allaire et al. 1991; Sanz et al. 2007; Engblom et al. 2008a). This might explain why in the current study sow mortality is high while culling due to lameness is low. The frequency of culling due to lameness was high for the
Specific reason
Peripartum problems Bad udders Dead piglets Multiple abscesses Multiple mummies Still births Total Production Miscellaneous Dystocia Emergence Sickness Savaging Selection Total
Number (frequency (%) and percent of the total)
4 (16.0, 0.3) 3 (12.0, 0.3) 1 (4.0, 0.1) 6 (24.0, 0.5) 11 (44.0, 1.0) 25 (100, 2.2) 26 (100, 2.2) 5 (17.2, 0.4) 4 (13.8, 0.3) 8 (27.6, 0.7) 2 (6.9, 0.2) 10 (34.5, 0.9) 29 (100, 2.5)
lower parities (0–2) agreeing with other findings (Friendship et al. 1986; Engblom et al. 2007; Mote et al. 2009). However, the current study also showed a high frequency of removal due to lameness in sows in parities ≥9 which is contrary to work showing that the risk of lameness decreases as parity increases (Lucia Jr et al. 2000; Segura-Correa et al. 2011). This is likely due to poor selection for structural soundness when sows are still in lower parities. Failure to select for structural soundness in early parities will increase the likelihood of sows suffering from bad legs, i.e. footrot, overgrown claws and torn dewclaws, when they reach older parities (Dewey et al. 1992, Dewey et al. 1993). Culling due to lameness was more frequent during the cold dry season which
100
Fig. 1 Frequency of culling by reason within the individual seasons
90
Culling frequency (%)
80 70 60 50
Seasons
40
Hot dry
30
Cold dry Warm wet
20
Hot wet
10 0
Culling reasons
Trop Anim Health Prod 100
Fig. 2 Contribution of culling reasons within each season
90
Culling frequency (%)
80 Culling reasons 70
Miscellaneous
60
Performance
50
Age
40
Peripartum problems Death
30
Lameness 20
Reproduction
10 0 Hot wet
is in agreement with the findings of Friendship et al. (1986) who reported a higher frequency of culling due to locomotor problems in winter. For peripartum problems, culling frequencies range between 2 and 36 % (Engblom 2008). Parities at greatest risk of culling due to peripartum problems are parities 1, 5 and 8 (D’Allaire et al. 1991), while other workers concluded that the risk was highest in the first parity (Engblom 2008). The current study agreed with these findings with regards to the frequency being high in first parity, but we also found that the highest frequency was for sows in parities ≥9. The specific reasons contributing the most to culling due to peripartum reasons were stillbirths and multiple mummies. Literature has clarified that older parities are more prone to both still births and multiple mummies (Borges et al. 2005; Segura-Correa and Solorio-Rivera 2013). Peripartum problems were more frequent in the cold dry season compared to all other seasons. This is in contradiction with work showing that the major components of peripartum problems (multiple mummification and stillbirths) have higher frequencies in summer (Phongphaewa et al. 2001). There is evidence suggesting that seasonal infertility increases late pregnancy losses in pigs (Bertoldo et al. 2009). Only sows in parities 7, 8 and ≥9 were culled due to age, and it was third in importance for parities ≥9. This is in agreement with other authors who reported an increase in culling frequency due to age as parity increased (D’Allaire et al. 1991; Lucia Jr et al. 2000; Segura-Correa et al. 2011). However, these authors also reported culling due to age in lower parities. The difference with this study is due to differences in the allocation of culling reasons where removals due to age were influenced by other factors such as keeping younger sows that have failed to reproduce indefinitely and eventually culling them due to age and not reproductive failure. The higher frequencies of culling due to age reported in literature compared to the current study can be explained by
Warm wet Cold dry Season
Hot dry
the overlap between culling due to age and productivity (Dhliwayo 2007, Segura-Correa et al. 2011) as well as inclusion of other factors within the age classification such as overweight sows in lower parities (D’Allaire et al. 1991). The fact that culling due to age was more frequent in the warm wet season is not indicative of a relationship between that season and culling frequency, since culling due to age is part of planned culling; this observation is merely a reflection of the management’s decision to cull most of the older sows during that season. Culling due to low productivity had a frequency that was much lower (2.2 %) than that reported in literature which has a range of 7–37 % (D’Allaire et al. 1991; Dhliwayo 2007; Mote et al. 2009; Segura-Correa et al. 2011). In the current study, low productivity was defined only as sows producing low litter sizes (
