The association of maternal fear on pre-weaning mortality of piglets in a group-farrowing system.

摘要

This project was designed to investigate the association of maternal fear on reproductive performance, changes in serum hormone concentrations, and maternal behavior of sows in a group-farrowing system. Multiparous sows (n = 64, parity 2 to 9) from 4 breeding groups that farrowed during winter and summer were used. Fear scores were calculated for each sow based on responses to the human approach and novel object tests during the early (2 to 4 wk) and late (10 to 12 wk) gestation periods. Sows were classified as fearful (n = 32, scores = 4.36 +/- 1.83) or less fearful (n = 31, scores = 7.32 +/- 0.42). One sow was taken off study due to illness. The farrowing facility housed 8 sows (4 classified as fearful and 4 less fearful) in each room (2 rooms/breeding group), where sows shared a communal area and farrowed in individual pens. Production performance, sow weight entering the farrowing room and at weaning, total born, born alive, and still born piglets in each litter, litter size after cross-fostering, and litter weight were recorded for each sow within 24 h after farrowing. Piglets were weighed and counted at pen removal at approximately 10 d (4 d to 15 d) of age. Less fearful sows had increased weight at weaning (P 0.02), and an increased litter weight at birth (P 0.02) compared to fearful sows. There was no significant association of fear, parity, or season with piglet mortality in the first 24 h and 72 h post-farrowing. Piglet mortality at pen removal was lower for fearful sows compared to less fearful sows (17.5% vs. 24.0%, SE = 3.2; Odd Ratio = 0.6, 95% Confidence Interval = 0.4 to 0.9).;A subset of sows (7 fearful and 7 least fearful) were chosen for blood sample collection to evaluate changes in selected hormones. Three days before the expected farrowing date of the first sow, sows were moved into the farrowing facility, anesthetized, and had an indwelling ear vein catheter inserted. A blood sample was collected from each sow once a day from 2 d pre-farrowing through 2 d post-farrowing between 1000 and 1100 h. Catheters in 11 sows (5 fearful and 6 less fearful) remained functional for the sampling period. Serum samples were analyzed for prolactin, oxytocin, cortisol and urocortin concentrations using RIA. There was no association of sow fear ( P > 0.30) with prolactin, oxytocin, cortisol, or urocortin concentrations on any day.;Sows (n = 64) were continuously video-recorded from 1 d prior to expected farrowing date until 3 d post-farrowing. Farrowing and nursing behaviors for 55 sows were successfully analyzed. Farrowing behaviors were analyzed using focal sampling with continuous observation. Nursing behaviors were analyzed using continuous observation of 1 h for every 4 h, starting from the delivery of the first piglet and ending 72 h after delivery of the last piglet of the litter. During farrowing, fearful sows had an increased number of all posture changes measured than less fearful sows. Additionally, fearful sows had an increased number of total posture changes and the posture change of rolling over in the first 72 h post-farrowing compared to fearful sows. However, the differences in these posture changes between fearful and less fearful sows were not related to piglet mortality during the first 72 h after farrowing.;In addition to the main research project, an extension project was designed to identify the major factors associated with pre-weaning mortality and develop management protocols to manage these factors on alternative production farms. A survey was developed and given to alternative swine producers in Minnesota and Iowa to identify the major factors associated with pre-weaning mortality on their farms. A management protocol to decrease pre-weaning mortality was developed based on the responses to this survey, and previous research completed by the authors. Six farms were chosen to participate in the study, and data from 4 farms are presented due to lost or incomplete records. Performance data (the number of total born, born alive, stillborns, litter size within the first 24 h of farrowing after cross-fostering, and litter size 10 d post-farrowing) were collected from November 2010 to May 2011 from 255 farrowings. Pre-weaning mortality on these farms was affected by a combination of factors including season, genetics, housing, and management practices. Management recommendations to decrease pre-weaning mortality based on the findings on each farm included increasing biosecurity, providing supplemental heat for piglets, providing additional bedding in muddy conditions, and reviewing sow environmental and nutritional management needs. The results of this study provided key focus areas on each farm aimed at decreasing pre-weaning mortality.