Realized heritability estimates in boars divergently selected for testosterone levels^1,2

Abstract

Data were collected from 1982 through 1992 from 100 sires and 891 Duroc boars. Testosterone production was measured from peripheral blood samples before (PRE) and after (POST) GnRH challenge. Additionally, data were collected on testes volume at 168 d (TVOL), days to 104 kg (DAYS104), number born alive (NBA) and backfat adjusted to 104 kg body weight (FAT). Realized heritabilities were estimated from the regression of response on cumulative selection differentials. Heritabilities for POST were .15 ± .18 and .24 ± .08 in the low and high lines, respectively. This compares with the estimate of .26 ± .21 from son-sire regressions. The regression of other traits on cumulative selection differentials can be viewed as realized correlated responses to selection. After 10 generations, the high line was approximately three times greater than the low line for both PRE and POST levels of testosterone. Although not significant, high line pigs required fewer days to reach 104 kg, had more backfat and larger testes than low line pigs. Litter size was significantly larger for high line than for low line. ZUSAMMENFASSUNG: Realisierte Heritabilitätsschätzungen von Divergenz für Testosteronspiegel selektierten Ebern Die Daten stammen aus dem Zeitraum 1982-1992 von 891 Duroc Ebern aus 100 Vatertieren. Testosteronproduktion wurde von peripheren Blutproben vor (PRE) und nach (POST) GnRH-Gaben gemessen. Zusätzlich wurden Angaben über Hodenvolumen am Tag 168 (TVOL), Zeitraum bis 104 kg Lebendgewicht (DAYS104), Zahl lebend geborener (NBA) und auf 104 kg Körpergewicht korrigierte Rückenspeckdicke (FAT) erhoben. Realisierte Heritabilitätswerte wurden aus der Regression von Selektionserfolg auf kumulative Selektionsdifferenzen geschätzt. Heritabilität für POST waren 0,15 ± 0,18 und 0,24 ± 0,08 in der Minus- und in der Pluslinie. Aus Sohn-Vater-Regressionen ergab sich 0,26 ± 0,21. Die Regression anderer Eigenschaften auf kumulative Selektionsdifferenzen können als realisierte korrelierte Selektionserfolge betrachtet werden. Nach 10 Generationen hatte die Pluslinie etwa dreimal höhere PRE- und POST-Spiegel von Testosteron als die Minuslinie. Obwohl nicht signifikant, brauchten Schweine der Pluslinie weniger Tage bis 104 kg, waren fetter und hatten größere Hoden als Schweine der Minuslinie. Die Wurfgröße der Pluslinie war höher als in der niedrigen Linie.

Genetic correlations between male reproductive traits and growth traits in growth performance tested Duroc, Landrace and Yorkshire breed boars

“…Low and narrow range of heritability estimates (0.12-0.20) of libido were found in this study which agreed with the 13 estimates (with 0.15 mean heritability estimate and a range of 0.03-0.47) summarized by Rothschild and Bidanel (1998). However, moderate to high heritability estimates with a range of 0.18-0.58 were observed in penile length, which supported the general cognition of moderate-to-high heritability values for most body composition traits, testes and accessory gland measurements, and thus were expected to easily respond to selection when compared to those selection responses from sperm characteristics (Robison et al 1994;Robic et al 2008;Bidanel 2011;Pinart & Puigmule 2013). Furthermore, heritability estimates of sperm concentration and total sperm counts were consistent with those reported on within-breed genetic variability in the review literature (Rothschild & Bidanel 1998;Bidanel 2011;Pinart & Puigmule 2013).…”

Sources of variation in HPG axis reactivity and individually consistent elevation of sex steroids in a female songbird

“…multiple measures of the exact same trait), our finding that gonadal output is individually consistent is analogous to repeatability, again suggesting that the individual variation reported here may reflect true individual differences. Others have reported repeatable variation in response to a GnRH challenge in male animals (Bergeon Burns et al, under revision; Jawor et al, 2006), and a few studies suggest high heritability of T production (Mills et al, 2009; Prove, 1978; Robison et al, 1994). In addition, artificial selection has been shown to affect other endocrine systems (e.g.…”

Elevated testosterone reduces choosiness in female dark–eyed juncos (Junco hyemalis): evidence for a hormonal constraint on sexual selection?

“…Although the heritability of T levels has not been measured in birds, evidence from domestic mammals suggests that T levels are heritable (Davis 1993;Robison et al 1994). Additionally, T-mediated traits such as comb size in fowl (Johnson et al 1993;Zuk et al 1995;Tufvesson et al 1999) and dominance in quail (Nol et al 1996) have been shown to have a heritable basis.…”