Re-Serviced Females on Commercial Swine Breeding Farms

Farm data analysis for lifetime performance components of sows and their predictors in breeding herds

Our objectives in this review are 1) to define the four components of sow lifetime performance, 2) to organize the four components and other key measures in a lifetime performance tree, and 3) to compile information about sow and herd-level predictors for sow lifetime performance that can help producers or veterinarians improve their decision making. First, we defined the four components of sow lifetime performance: lifetime efficiency, sow longevity, fertility and prolificacy. We propose that lifetime efficiency should be measured as annualized piglets weaned or annualized piglets born alive which is an integrated measure for sow lifetime performance, whereas longevity should be measured as sow life days and herd-life days which are the number of days from birth to removal and the number of days from date of first-mating to removal, respectively. We also propose that fertility should be measured as lifetime non-productive days, whereas prolificacy should be measured as lifetime pigs born alive. Second, we propose two lifetime performance trees for annualized piglets weaned and annualized piglets born alive, respectively, and show inter-relationships between the four components of the lifetime performance in these trees. Third, we describe sow and herd-level predictors for high lifetime performance of sows. An example of a sow-level predictor is that gilts with lower age at first-mating are associated with higher lifetime performance in all four components. Other examples are that no re-service in parity 0 and shorter weaning-to-first-mating interval in parity 1 are associated with higher fertility, whereas more piglets born in parity 1 is associated with higher prolificacy. It appears that fertility and prolificacy are independent each other. Furthermore, sows with high prolificacy and high fertility are more likely to have high longevity and high efficiency. Also, an increased number of stillborn piglets indicates that sows have farrowing difficulty or a herd health problem. Regarding herd-level predictors, large herd size is associated with higher efficiency. Also, herd-level predictors can interact with sow level predictors for sow lifetime performance. For example, sow longevity decreases more in large herds than small-to-mid herds, whereas gilt age at first-mating increases. So, it appears that herd size alters the impact of delayed gilt age at first-mating on sow longevity. Increased knowledge of these four components of sow lifetime performance and their predictors should help producers and veterinarians maximize a sow's potential and optimize her lifetime productivity in breeding herds.

Characteristics and risk factors for severe repeat-breeder female pigs and their lifetime performance in commercial breeding herds

BACKGROUND

Repeat-breeder females increase non-productive days (NPD) and decrease herd productivity and profitability. The objectives of the present study were 1) to define severe repeat-breeder (SRB) females in commercial breeding herds, 2) to characterize the pattern of SRB occurrences across parities, 3) to examine factors associated with SRB risk, and 4) to compare lifetime reproductive performances of SRB and non-SRB females. Data included 501,855 service records and lifetime records of 93,604 breeding-female pigs in 98 Spanish herds between 2008 and 2013. An SRB female pig was defined as either a pig that had three or more returns. The 98 herds were classified into high-, intermediate- and low-performing herds based by the upper and lower 25th percentiles of the herd mean of annualized lifetime pigs weaned per sow. Multi-level mixed-effects logistic regression models with random intercept were applied to the data.

RESULTS

Of 93,604 females, 1.2% of females became SRB pigs in their lifetime, with a mean SRB risk per service (± SEM) of 0.26 ± 0.01%. Risks factors for becoming an SRB pig were low parity, being first-served in summer, having a prolonged weaning-to-first-mating interval (WMI), and being in low-performing herds. For example, served gilts had 0.81% higher SRB risk than served sows (P < 0.01). Also, female pigs in a low-performing herd had 1.19% higher SRB risks than those in a high-performing herd. However, gilt age at-first-mating (P = 0.08), lactation length (P = 0.05) and number of stillborn piglets (P = 0.28) were not associated with becoming an SRB female. The SRB females had 14.4-16.4 fewer lifetime pigs born alive, 42.8-91.3 more lifetime NPD, and 2.1-2.2 lower parities at culling than non-SRB females (P < 0.05).

CONCLUSIONS

We recommend that producers closely monitor the female pig groups at higher risk of becoming an SRB.

Factors for improving reproductive performance of sows and herd productivity in commercial breeding herds

We review critical factors associated with reproductive performance of female breeding pigs, their lifetime performance and herd productivity in commercial herds. The factors include both sow-level and herd-level factors. High risk sow-level groups for decreasing reproductive performance of female pigs are low or high parity, increased outdoor temperature, decreased lactation feed intake, single inseminations, increased lactation length, prolonged weaning-to-first-mating interval, low birth weight or low preweaning growth rate, a few pigs born alive at parity 1, an increased number of stillborn piglets, foster-in or nurse sow practices and low or high age at first-mating. Also, returned female pigs are at risk having a recurrence of returning to estrus, and female pigs around farrowing are more at risk of dying. Herd-level risk groups include female pigs being fed in low efficiency breeding herds, late insemination timing, high within-herd variability in pig flow, limited numbers of farrowing spaces and fluctuating age structure. To maximize the reproductive potential of female pigs, producers are recommended to closely monitor females in these high-risk groups and improve herd management. Additionally, herd management and performance measurements in high-performing herds should be targeted.

Factors associated with a single-mating occurrence in first-serviced and reserviced female pigs on commercial farms

This study investigated associations of a single-mating occurrence (SMO) with farrowing rate and pigs born alive (PBA) in first-serviced and reserviced female pigs (females), and identified the factors associated with SMO. The data included 111,334 service and 91,233 farrowing records on 117 farms. A mating was defined as any one insemination (mating) of a female during estrus. Mixed-effects models were used to investigate reproductive performance and factors associated with SMO. In the first-service group, single-mated females had a lower farrowing rate and fewer PBA than multiple-mated females (P<0.05). In the reservice group, single-mated females also had a lower farrowing rate than multiple-mated females (P<0.05), but had PBA similar to multiple-mated females. SMO in first-service and reservice groups were 4.1 and 6.0%, respectively. Gilts were 1.030 times more likely to be mated a single time than sows (P<0.05). Gilts with age at first mating 150-224 and > or = 262 days were 1.010-1.016 times more likely to be mated a single time than those with age at first mating 225-260 days (P<0.05). Sows with weaning-to-first-mating interval > or = 7 days were 1.024-1.030 times more likely to be mated a single time than those with weaning-to-first-mating interval < or = 6 days (P<0.05). Factors associated with a higher SMO were a reservice occurrence, being gilts, low or high ages of gilts at first mating, and prolonged weaning-to-first-mating interval.

An evaluation of the impact of increased lactation length on the reproductive efficiency of sows in commercial herds

The objective of this study was to evaluate the impact of increased lactation length (LL) on the reproductive efficiency of sows in herds that were performing differently. The present study used 69,314 parity records for 38,532 sows in 114 herds. Two herd groups, high-performing herds and other herds, were formed on the basis of the upper 25th percentile of pigs weaned per mated female per year. Reproductive efficiency was measured as the estimated number of pigs born alive per farrowed sow per year (PBASY) and was calculated as actual subsequent pigs born alive (PBA) multiplied by estimated litters per farrowed sow per year (LSY) for each farrowed sow. The estimated LSY was calculated as 365 days divided by the actual farrowing interval. Multilevel linear mixed-effects models were used. In our evaluation, an interaction between LL and the herd groups was found for the estimated PBASY (P<0.05). The estimated PBASY of high-performing herds did not decrease as LL increased (P>0.10), although the estimated PBASY of the other herds decreased by 0.04 pigs as LL increased by 1 day (P<0.05). As LL increased from 14 to 28 days, the estimated LSY decreased by 0.19 in the two herd groups (P<0.05). Furthermore, as LL increased by 1 day, subsequent PBA increased by 0.08 pigs in high-performing herds and increased by 0.04 pigs in the other herds (P<0.05). Increased LL may not decrease the performance of sows in high-performing herds, but it may decrease the performance in other herds.

Six component intervals of nonproductive days by breeding-female pigs on commercial farms

Of 105 swine herds using a production record system for breeding female pigs, 95 farms were used to analyze nonproductive female days (NPD), the six component intervals of NPD, and related measurements. The NPD was defined as the days when mated gilts and sows were neither gestating nor lactating, and it was calculated by summing the six component intervals in the average mated female inventory. The mean NPD was 57.9 d (SD = 20.5), and the proportions of six component intervals of gilt first-mating-to-pregnancy interval, gilt first-mating-to-culling interval, unmated weaning-to-culling interval, weaning-to-first-mating interval, sow first-mating-to-pregnancy interval, and sow first-mating-to-culling interval were 9.24, 7.82, 6.85, 27.9, 18.9, and 29.3%, respectively. Farms in the upper 25th percentile of the ranking for number of pigs weaned.mated female(-1).yr(-1) were designated as 25 high-performing farms. The remaining farms were designated as an ordinary farm group for comparisons. High-performing farms had 21.1 d fewer NPD, and five of the six component intervals were lower compared with the ordinary farms (P < 0.05). Regression analyses indicated that the number of litters.mated female(-1).yr(-1) increased by 0.07 in both farm groups as NPD decreased every 10 d. Fewer NPD were correlated with a higher percentage of multiple matings during estrus (P < 0.05) but were not correlated with removal risk and replacement risk in both farm groups. The average parity of culled females was negatively correlated with NPD in the ordinary farm group, and the average farrowed parity was positively correlated with NPD in the high-performing farm group (P < 0.01). Decreasing each component interval of the NPD six components is critical to increasing herd productivity. A high percentage of multiple matings during estrus and appropriate culling management may be key factors to decrease NPD.

Within-farm variability in age structure of breeding-female pigs and reproductive performance on commercial swine breeding farms

This study investigated relationships between herd age structure and herd productivity in breeding herds; it also investigated a pattern in parity proportions of females over 2 years and its relationship with herd productivity in commercial swine herds. This study was based on data from 148 commercial farms in North America stored in the swine database program at the University of Minnesota. The primary selection criterion was fluctuations in breeding-female pig (female) inventories over a 2-year interval. Productivity measurements and parity proportions of females were extracted from the database. A 24-month time-plot in proportions of Parity 0 and Parities 3-5 females (mid-parity) was charted for each farm. Using these charts, a change in proportions of Parity 0 and mid-parity for each farm was categorized into patterns: FLUCTUATE (Parity 0 and mid-parity proportion lines crossed) or STABLE (the two proportion lines never crossed). Higher proportions of mid-parity sows were correlated with greater pigs weaned per female per year (PWFY; P < 0.01). Farms with a FLUCTUATE (73% of the 148 farms) pattern had lower PWFY than those with a STABLE pattern (P < 0.01). The STABLE farms had higher proportions of mid-parity sows, higher parity at culling, higher frequency of gilt deliveries per year, and lower replacement rate than the FLUCTUATE farms (P < 0.01). In conclusion, maintaining stable subpopulations with mid-parity and Parity 0 are recommended to optimize herd productivity.