Sow removal in a commercial pig herd in Zimbabwe

Assessing reproductive performance and predictive models for litter size in Landrace sows under tropical conditions

OBJECTIVE

Litter size and piglet loss at birth significantly impact piglet production and are closely associated with sow parity. Understanding how these traits vary across different parities is crucial for effective herd management. This study investigates the patterns of the number of born alive piglets (NBA), number of piglet losses (NPL), and the proportion of piglet losses (PPL) at birth in Landrace sows under tropical conditions. Additionally, it aims to identify the most suitable model for describing these patterns.

METHODS

A dataset comprising 2,322 consecutive reproductive records from 258 Landrace sows, spanning parities from 1 to 9, was analyzed. Modeling approaches including 2nd and 3rd degree polynomial models, the Wood gamma function, and a longitudinal model were applied at the individual level to predict NBA, NPL, and PPL. The choice of the best-fitting model was determined based on the lowest mean and standard deviation of the difference between predicted and actual values, Akaike information criterion (AIC), and Bayesian information criterion (BIC).

RESULTS

Sow parity significantly influenced NBA, NPL, and PPL (p<0.0001). NBA increased until the 4th parity and then declined. In contrast, NPL and PPL decreased until the 2nd parity and then steadily increased until the 8th parity. The 2nd and 3rd degree polynomials, and longitudinal models showed no significant differences in predicting NBA, NPL, and PPL (p>0.05). The 3rd degree polynomial model had the lowest prediction standard deviation and yielded the smallest AIC and BIC.

CONCLUSION

The 3rd degree polynomial model offers the most suitable description of NBA, NPL, and PPL patterns. It holds promise for applications in genetic evaluations to enhance litter size and reduce piglet loss at birth in sows. These findings highlight the importance of accounting for sow parity effects in swine breeding programs, particularly in tropical conditions, to optimize piglet production and sow performance.

Characterization of Removal Reasons for Nurse Sows and the Associated Removal Due to Their Extended Lactation Length in Hyperprolific Farrow-Wean Herds

This study aimed to characterize and quantify reasons for the removal of nurse sows and identify the removal associated with their extended lactation length (ELL). A total of 100,756 removed nurse sows within a period of 2016-2022 from 53 sow herds in the Midwest USA were analyzed. Reproductive failure was the most common removal reason (χ2 = 8748.421, p < 0.001) affecting P1, P2, and P3 nurse sows. Failure to conceive and absence of estrus were the main causes of reproductive failure (χ2 = 352.480, p < 0.001) affecting P1 and P2 nurse sows and P1 and P5 nurse sows, respectively. When P2 and P6 nurse sows had an ELL of 0-7 d, they faced a high chance (χ2 = 13.312, p = 0.021) of removal due to conception failure and failure to return to heat, respectively. When P2 and P5 nurse sows had an ELL of 8-14 d, they were highly vulnerable (χ2 = 59.847, p < 0.001) to removal due to failure to conceive and showing heat, respectively. Finally, when ELL was at 15-21 days, P4 and P5 nurse sows were more likely (χ2 = 41.751, p < 0.001) to be removed due to failure to express heat, whereas at the same time, P2 and P3 nurse sows experienced the same removal threat due to failing to conceive. These results could help producers manage nurse sow systems.

Optimizing feeding regimen of replacement gilts to improve their reproductive performance and retention rate of their first 2 parities

The effects of age, body weight (BW), and backfat thickness (BF) of replacement gilts at first estrus and first mating on their subsequent reproductive performance and retention of their first 2 parities as sows was evaluated. A total of 3,025 Danish replacement gilts were categorized by farm (allocated to 4 farms), cross combination, age, BW and BF at first estrus and first mating, estrous cycle number at first mating, and flush feeding before first mating. The result shows that all the factors mentioned above were significantly associated with reproductive performance and retention rates of the first 2 parities. Farm 3 had more piglets born alive per litter (BA) (P < 0.05). Farms 3 and 4 had more healthy piglets per litter (HP) (P < 0.05). Farm 4 had the most piglets weaned per litter (PW) (P < 0.05). Landrace × Landrace × Yorkshire (L × L × Y) replacement gilts had the most total piglets born per litter (TB), BA, HP, PW and a higher retention rate of the 2 parities than Landrace × Yorkshire (L × Y) replacement gilts (P < 0.05). In addition, flush feeding before first mating had the most TB, BA, HP, PW, and a higher retention rate of the 2 parities than no flush feeding (P < 0.05). Because the effects of replacement gilts rearing parameters on reproductive performance traits differed, we used 100 replacement gilts as a unit and the total number of weaned piglets from the first 2 parities as a new index. Replacement gilts undergoing their first estrus between 180 and 210 d of age at 115 to 124.9 kg BW and 14 to 15 mm BF had significantly higher reproductive indexes for their first 2 parities per 100 replacement gilts. Replacement gilts that mated between 210 and 230 d of age at 140 to 149.9 kg BW and 15 to 16 mm BF had optimal reproductive indexes. These results provide a new insight into the complex relationships among these reproductive performance traits and may help guide successful management of replacement gilts as a pivotal starting point for future fertility and longevity of rearing herds.

Removal of sows in Spanish breeding herds due to lameness: Incidence, related factors and reproductive performance of removed sows

Lameness is a major reason for sow removal in breeding herds. Increased removal occurrences for lameness decrease reproductive efficiency and increase welfare concerns. Therefore, the objectives of this study were to estimate the incidence rate of removal due to lameness, and to investigate the longevity and reproductive performance of sows removed due to lameness. Poisson regression models were applied to a cohort dataset of 137,907 sows in 134 herds located in Spain. The Wilcoxon rank sum test was used to compare the performance of sows removed due to lameness and their controls in one-to-two matched case-control datasets. Removal due to lameness accounted for 4.3 % of all removed sows, and the incidence rate was 19.6 cases per 1000 sow-years (95 % confidence interval: 15.03, 25.51). The majority (70.4 %) of those removed were farrowed sows, whereas only 29.6 % were serviced sows. In farrowed sows, a higher incidence of removal due to lameness was associated with weeks 4-9 after farrowing, higher parity and winter farrowing (P <  0.01). The removal incidence was 24.7-33.1 times higher in weeks 4-9 after farrowing than during the first week after farrowing (P <  0.01). It was 1.3-1.6 times higher in parity 4-5 than in parity 1, and 1.3 times higher for winter farrowing than for summer farrowing (P <  0.01). In contrast, the factors associated with removal due to lameness with serviced sows were weeks 4-5 after service and being re-serviced (P <  0.01). The service sow removal incidence was 4.7 times higher in weeks 4-5 after servicing than during the first 2 weeks after servicing (P <  0.01). Also, it was 2.2 times higher in re-serviced sows than in first serviced sows (P <  0.01). However, removal in serviced sows was not associated with parity (P =  0.10) or service season (P =  0.39). In the case-control datasets, the sows removed due to lameness had higher weaning-to-first-mating interval (means: 6.5 vs. 5.8 days), fewer piglets born alive (11.7 vs. 12.5 piglets) and lower parity at removal (3.4 vs. 4.9; P <  0.01) than sows removed for other reasons or non-removed sows. However, there was no difference in gilt age at first service between the case and control groups (P =  0.29). We recommend identifying sows showing early signs of lameness and treating them with pain medication until removal. The best time for removal would be at weaning when non-productive sow days start.

An Analysis of Culling Patterns during the Breeding Cycle and Lifetime Production from the Aspect of Culling Reasons for Gilts and Sows in Southwest China

Simple Summary

Unplanned removal of gilts and sows shortens the longevity and decreases the production efficiency of commercial herds. A comparison between sow culling studies is problematic due to differences in genetics, housing conditions, and feeding and management among different countries. Analyzing and monitoring culling patterns in sows in a particular area could help improve domestic feeding and the managing level. Based on the large sample of production data, we found that disease, lameness, return to estrus, and anestrus beyond seven days sharply decreased lifetime production in sows. We suggest that producers take effective measures to reduce anestrus beyond nine months, reproductive system disease, return to estrus, and low or no milk production for gilts, weaned sows, gestating sows, and lactating sows, respectively. We also recommend producers pay more attention to disease, lameness, and return to estrus for sows at low parity.

Abstract

To investigate culling patterns during the breeding cycle and lifetime production associated with culling reasons, 19,471 culling records were collected in southwest China. Lifetime pigs born alive (LPBA) and parity for culling reasons, and reason distribution at different parities and breeding cycle were analyzed. Sows culled for stress and death (SD), lameness (LA), common disease (CD), not being pregnant, return to estrus, and abortion (NP) had fewer than 20 LPBA (p < 0.05). Gilts were mainly culled for anestrus beyond nine months (AB9), CD, and LA, while weaned sows were culled for reproductive system disease (RS), CD, and anestrus beyond seven days (p < 0.0033). Gestating sows were mainly culled for NP, CD, and SD, while lactating sows were mainly culled for low or no milk production (NM), poor litter size, and CD (p < 0.0033). Moreover, sows were mainly culled at parity 0, 1, and 2 (p < 0.0024). Besides CD and RS, LA and NP were the primary reasons for parity 1 and 2 culls, respectively. In conclusion, SD, LA, CD, and NP sharply decrease sow lifetime production. AB9, RS, NP, and NM mainly occurred in gilts, weaned, gestating, and lactating sows, respectively. Low parity sows had a higher risk of CD, RS, LA, and NP.

Analysis of reasons for sow culling and seasonal effects on reproductive disorders in Southern China

Sow culling rates have a direct correlation to the economic efficiency of both breeding herd and commercial herd. Analyzing the reasons of sow culling could lead to improve production efficiency of farms. This study, which involved inspections of four farms in Southern China, manifested that the rate of unplanned sow-culling has reached to 78.1% in total culls. In which, reproductive disorders and lameness accounted for 35.3% and 22.5%, respectively. The average parity of culled sows was 4.9, but a high proportion (19.6%) of sows was culled at their first parity. Anestrus, the highest proportion of reproductive disorders, accounting for 47.7%, occurred in July followed by June (17.7% and 11.8% respectively). The frequency of culling due to reproductive disorders in Southern China was higher than others regions, which suffered from the high temperature and humidity in Southern China. The frequency of sow culling reached its peak in the summer, specifically in July (12.3%), which means that hot weather has an adverse effect on sow culling. Pig farmers should take effective measures to reduce heat stress as nutrition strategies or cooling systems in gestation and/or farrowing sow herds between May and July in Southern China.