Impact of Managing Gilt Service Interval on Gilt Performance
Helpful reports can be used for herd improvement.
By Sasha Gibson and Jayne Jackson
This study investigated relationships between gilts that had at least one recorded estrus prior to breeding compared to gilts that had none. The subsequent performance over their lifetime was compared with gilts that did not have a recorded heat. This population study was conducted using 258 farms (330,000 sows) that are located in North America. The data was sourced from PigCHAMP® Knowledge Center Database from 2007 to 2009. This article provides insight into recording and heat-checking gilts. Data was analyzed from the PigCHAMP® Farrow to Finish Program using four reports:
- First Litter Performance
- Reproductive Loss Report
- Subsequent Litter Performance
- Age at First Service Analysis
Most farms have a dedicated gilt development plan. This includes a separate set of buildings to raise the animals, more square footage than commercial animals, breeding gilts older than 220 days, 300 lbs. in weight and specialized diets. Industry recommendations for gilt management include breeding gilts on the second or third estrus. The data analyzed shows that the percentage of gilts with recorded Heat No Service (HNS) events increased from 2007 to 2009 by 4 percent. This population study includes 190,000 gilt breeding events, and 18 percent of the total gilts bred had at least one Heat No Service (HNS) event recorded.
The entry age of the gilts with an HNS event recorded was 218 days, with an entry-to-service interval of 47days (Figure 1). Gilts were bred at an average of 264 days of age (2007 to 2009).
The entry age of the gilts without a heat recorded was 223 days, with an entry-to-service interval of 33 days (Figure 2). Gilts were bred at an average of 252 days of age (2007 to 2009).
The gilts that had an HNS event were not bred within 20 days of arrival into PigCHAMP. The act of entry is usually associated with a tagging or tattooing event for the gilts. On the No Heat Recorded group, 36 percent were bred within 20 days (Figures 3 & 4).
Total born was .9 of a piglet higher on the gilts that had an observed heat recorded. There were 0.7 more live born piglets per litter for HNS parity-one farrowings than no heat recorded gilts (Figure 5).
Reproductive loss was compared for all parities bred in the first six months of 2009. The sows that had a Heat No Service event when they were gilts were compared to No Heat (Table 1: Performance Averages on All Parities).
Subsequent litter performance was used to analyze how total born in the first litter affects future performance. Gilts that farrowed in 2008 were followed through the end of 2009. The HNS gilts have more total born and live born on the first farrowing, and this remains higher throughout their lifetime performance (Figures 6 & 7). This live born, cumulative through parity six, was 2.1 piglets.
Benefits are evident
Genetic improvements have occurred over time and management practices have become more attuned to the needs of the gilt. This has all led to an increase in production. Although 18 percent of the gilts have a heat recorded, there is a clear benefit to observing heats prior to servicing the gilts. Total born and live born numbers improve in the first farrowing and this improvement stays throughout the lifetime of the gilt.
This increase of half-a-pig live born each time the HNS animals farrow equates to a real return on observing and recording Heat No Service events on the gilt.
In addition to total-born increases, farrowing rates were higher on the HNS gilts. Observing and recording HNS would seem to capture the higher ovulation rates that occur on the second cycle. It could also be that gilts that are HNS have additional time to acclimatize to their new breeding/gestational surroundings before being bred. The arrival-to-service of at least 20 days before the HNS gilts were bred compared to No Heat gilts that had 36 percent bred within 20 days is likely part of the reproduction picture.
Analyze the Impact of Managing Gilt Service Interval on Lifetime Gilt Performance
To compare the subsequent performance over the lifetime of gilts that had at least one recorded estrus (observed heat) prior to breeding to gilts that had no recorded estrus (observed heat) prior to breeding in your PigCHAMP database you will need to customize and filter the following four reports.
- First Litter Performance Report: Analyzes detailed farrowing information for parity-one sows that farrowed within the userdefined reporting period.
- Reproductive Loss Report: Analyzes the relationship between service performance results based on various production factors; Parity or Cycle, Previous Lactation Length, Age at First Service, Wean to First Service Intervals and Arrival/Gilt Made Available to First Service Interval.
- Subsequent Litter Performance: Analyzes the effects on subsequent litter performance based on the first parity performance of a sow (Farrowed Gilts). Users are able to analyze the first parity total born, live born and stillborn; the effect the number born has on sows' subsequent number-born performance.
- Age at First Service Analysis: Analyzes the age of gilts at first service and the effect age has on their subsequent performance. A scattergraph format compares age versus total born, liveborn, stillborn, mummified, farrowing rate and repeat rate. The report also includes a histogram representing the age structure of the gilts first served in the reporting period.
For instructions on how to use the report customization tool, please refer to your program user guide, help files and/or watch the how-to video, "Customizing Reports in PigCHAMP Care 3000," available in the PigCHAMP University library at www.pigchamp.com. For all reports, you will need to add the following variable to each report using the Custom Report Items feature:
- For customers using the PigCHAMP Reproductive-only version, the reporting item needed for the filter will be located under the General Section > select Number of Gilt Heat Detections.
- For those customers using the newly released Farrow to Finish program, the reporting item needed for the filter will be located under the Mating Department Events > Observed Heats > select Gilt Observed Heats.
The Gilt Heat Detections/Observed Heats variable results in the total number of recorded observations that have occurred before the gilt was served for the first time for each individual female included within the defined reporting period. After the variable has been added to each custom report, please save the report settings for future use within the program.
To analyze the impact on the lifetime performance that gilt heat detections have; select each individual report and define the dates according to females you wish to analyze. After the report is processed, you will apply two separate filters to the results using the same custom-added variable.
For instructions on how to apply filters to a report, please refer to your program user guide, help files and/or watch the how to video, "Applying Report Filters in PigCHAMP Care 3000," available in our PigCHAMP University library at www.pigchamp.com.
The below filters will be applied separately to the processed report; once the filter is applied to the report, the results will be specific to the females that meet the filtered criteria. After the report is filtered, either save the report as a PDF and/or export results to Excel.
- Filter for gilts with a recorded estrus (observed heat): Gilt Heat Detections/ Observed Heats > 0 (Figure 1) Prior to filtering for the gilts that have not had a recorded estrus (observed heat) prior to breeding; select in the filter option dropdown "No Filter".
- Filter for gilts without a recorded estrus (observed heat): Gilt Heat Detections/Observed Heats = 0 (Figure 2)