The effect of lean growth rate on puberty attainment in gilts2

Abstract

Two hundred sixteen prepubertal Genex Manor hybrid F1 gilts were used to determine the impact of lean growth rate on sexual development of gilts. This study was composed of two experiments (Exp. 1 and Exp. 2). In Exp. 1, at approximately 96 d of age and 54 kg weight, gilts were allocated with respect to growth rate and litter origin to one of two dietary treatments: 1) a diet formulated to maximize lean growth potential (LP; n = 84) or 2) a diet formulated to produce a lower lean growth rate (LL; n = 84). In Exp. 2, at approximately 88 d of age and 50 kg weight, gilts were allocated with respect to growth rate and litter origin to one of two dietary treatments: 1) a diet formulated to maximize lean growth potential (LP; n = 24) or 2) a diet formulated to restrict lean growth further than was achieved in LL in Exp. 1 (RL; n = 24). All gilts were fed treatment diets for ad libitum consumption and housed in groups of six. Weight, backfat depth and loin depth, and feed intake were measured weekly. Starting at 135 d of age, gilts received 20 min of direct daily exposure to a boar as a pen group for pubertal stimulation. Puberty attainment was determined as the day gilts first exhibited the standing reflex in response to contact with a boar. At pubertal estrus, body weight, backfat depth, and loin depths were recorded. Diet affected (P < or = 0.05) estimated fat-free lean gain (LP, 424 vs LL, 347 g/d, Exp. 1; LP, 397 vs RL, 376 g/d, Exp. 2) during the growth period (start to stimulation). However, age at puberty was not affected by diet (LP, 157.3 vs LL, 157.6, Exp. 1; LP, 166.7 vs RL, 167.3, Exp. 2) or overall lean growth at stimulation (P > or = 0.05 in both experiments), confirming that innate variability in sexual development of commercial genotypes, rather than growth performance, determines onset of sexual maturity. A negative correlation between age at puberty and growth rate from 50 kg until puberty (P < or = 0.05) (LP, r = -0.40, LL, r = -0.36, Exp. 1; LP, r = -0.64, RL, r = -0.48, Exp. 2) was a consequence of reduced lean tissue growth during the stimulation period in later-maturing gilts.

The effect of the MC4R gene on boar taint compounds, sexual maturity and behaviour in growing-finishing boars and gilts

“…AA gilts had lower meat percentage and muscle thickness, higher fat thickness and lower ham width compared with GG gilts (Van den Broeke et al, 2015). Our results are therefore in accordance with the results of Rozeboom et al (1995) and Patterson et al (2002), that is that no association can be found between body conformation and the attainment of puberty in gilts.…”

Effects of restricting energy during the gilt developmental period on growth and reproduction of lines differing in lean growth rate: Responses in feed intake, growth, and age at puberty1

“…Although current industry practices avoid severely over-or underfeeding gilts during the developmental period, relatively little information is available regarding the effects of energy/nutrient intake on prepubertal estrus expression and subsequent sow productivity. Patterson et al (2002) compared the effects of diets formulated to maximize lean gain vs. reduced energy/lysine diets on puberty attainment in gilts. Age at puberty was not affected by average lean growth from 50 kg to 135 d of age (initiation of boar stimulation/ heat detection).…”

“…To develop practical gilt developmental regimens, it will be important to know effects on lifetime production. Several studies have examined the effects of nutrient manipulation during the growth period, gestation, or both on reproductive performance during the subsequent lactation (Hoppe et al, 1990;Newton and Mahan, 1993;Patterson et al, 2002). Our experiment is the first designed to examine the effects of genetic line and feeding regimen (energy intake) on gilt development and subsequent reproduction through 4 parities.…”

Genetic relationships of body composition, serum leptin, and age at puberty in gilts12

“…It has been postulated that a certain level of body condition is necessary for puberty attainment in gilts (Gaughan et al, 1997), whereas dietary treatments do not seem to affect pubertal age (Patterson et al, 2002). However, gilts with greater growth rate and backfat have shorter weaning to estrus intervals (Tummaruk et al, 2001) and age at puberty is positively genetically correlated with weaning to estrus interval and signs of estrus (Sterning et al, 1998).…”