The U.S. hog industry's shift to vertically-integrated, intensively-managed operations brought about a variety of management systems for breeding herds, including batch farrowing. In this system, groups of sows are weaned in 2- to 5- week intervals, making estrus synchronization of new gilts and sows critical to maintaining reproductive efficiency in the herd. The use of commercially available hormones to synchronize estrus in this system has not been extensively studied. This experiment was conducted to determine whether the use of commercially available hormones (MATRIX® and P.G. 600®; Merck Animal Health, De Sota, KS) in a 5-week batch management system had a positive impact on reproductive efficiency in gilts and sows over the course of 3 parities. Gilts were allocated to an Entry Group (A, B, or D) and then assigned to a treatment, Hormone-Assisted (HA) (5 mL P.G. 600 injection 5 days and/or fed 15 mg/day of MATRIX for 14 consecutive days prior to the breeding week) or Control (no exogenous hormones). Gilts and sows were checked daily for estrus with a mature boar, and a group was bred using AI during a 7-day breeding period every 5 weeks and allowed to farrow up to 3 parities. Among groups, there was a tendency (P = 0.08) for more HA than control gilts to display estrus and be mated on schedule. For gilts within Group A, more (P < 0.01) HA than control females displayed estrus and were mated. Body weight at first service for gilts in Groups A and B were higher than Group D (P < 0.01). Overall, there was no effect of treatment on (P = 0.20) non-productive days. There was a strong tendency for HA sows to have a greater (P = 0.07) number of parities completed than control sows; Total pigs born (P < 0.05) and total pigs born alive (P < 0.05) were greater for HA sows than control sows. In Parity 1, Group D sows had a lesser number of pigs born (P < 0.01) and pigs born alive (P < 0.02) than Groups A and B; The number of pigs weaned differed between entry groups (P < 0.05) (Group B > Group A > Group D); Control sows weaned more pigs (P < 0.02) and had a greater litter weaning weight (P < 0.01) than HA sows; HA sows had a lower (P < 0.05) wean-to-estrus interval than control sows. No significant effects of group or treatment were observed in Parities 2 and 3. The use of exogenous hormones to synchronize estrus had a positive impact on reproductive efficiency in HA gilts/sows in a 5-week batch management system. / Master of Science
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/54594 |
| Date | 23 July 2015 |
| Creators | Petrone, Rosalie Catherine |
| Contributors | Animal and Poultry Sciences, Estienne, Mark J., Wood, Cynthia M., Ealy, Alan D. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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