Gilt development traits associated with genetic line, diet and fertility
Introduction
Studies quantifying the effect of gilt traits on subsequent reproductive performance (Knauer et al., 2010, Lόpez-Serrano et al., 2000, Serenius and Stalder, 2004, Tholen et al., 1996, Yazdi et al., 2000) typically do not include gilts that fail to farrow. However, gilts that fail to farrow are costly to producers in that they increase gilt development costs and reduce sow herd efficiency. Studies report 8–29% of gilts do not farrow a litter (Cronin et al., 1983, Moeller et al., 2004). Reproductive failure is the leading cause of gilt removals according to retrospective farm record analysis (Stalder et al., 2004). However, reported farm culling reasons contain errors (Knauer et al., 2007a). Examination of reproductive tracts at harvest facilities can confirm farm records. Post-mortem examinations in gilts and sows (Heinonen et al., 1998, Knauer et al., 2007b) revealed that most females culled have normal ovaries. Thus, factors explaining why gilts do not farrow for reproductive or other reasons are not well understood.
Studies have quantified the relationship between gilt body weight and body composition, achieved through dietary manipulation, on subsequent reproductive performance (Barczewski et al., 1990, Johnson et al., 2009, Klindt et al., 2001, Newton and Mahan, 1993, Stalder et al., 1998). However, few studies have examined estrous traits in relation to subsequent reproductive performance (Cronin et al., 1982, Gäde et al., 2006). To the author's knowledge, no gilt development study has comprehensively evaluated gilt estrous, puberty, growth, body composition and structural conformation traits. Therefore, the objective of this study was to associate gilt entry, estrous, puberty, growth, body composition, structural conformation and sow traits with genetic line, gilt development diet and fertility.
Section snippets
Materials and methods
The protocol for the experiment was reviewed and approved by the Institutional Animal Care and Use Committee at North Carolina State University.
Genetic line
Estrous and puberty traits are shown by genetic line in Table 3. Large White gilts in comparison to Lan, F1 and Composite females had a shorter (P<0.05) length of estrus (1.91 d vs. 2.16–2.21 d) and total strength of standing reflex with a boar (13.7 vs. 15.4–15.5). However, maximum strength of standing reflex without a boar and total strength of standing reflex without a boar were higher (P<0.05) for LW in comparison to Lan, F1 and Composite females (13.9 vs. 11.0–12.6). Yet, genetic lines did
Discussion
Replacement gilt programs strive to produce females that reach puberty at a young age, farrow a litter, wean large numbers of high quality piglets and have superb subsequent reproductive performance. The present study adds new genetic and management information towards developing an optimal replacement gilt program to achieve these goals.
Genetic line differences were established for estrous, growth, composition and structural conformation traits. These results indicate producers can use between
Summary
The current study provides new information towards developing an optimal replacement gilt program. Genetic line differences for estrous traits indicate between line selection is feasible. In gilt group 3, females that were restrictively fed from 200 to 270 days of age in comparison to those fed ad libitum had a longer length of estrus, stronger total strength of standing reflex with a boar and were younger at puberty. Differing gilt development diets created differences in gilt weight and
Role of the funding source
North Carolina Pork Council funded part of this project. However, they did not play a role in study design; collection, analysis and interpretation of the data; in writing of the report; or in the decision to submit the paper for publication.
Conflict of interest statement
We wish to confirm that there are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome.
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