Genetic and environmental effects on age at first farrowing in sows in southeastern Brazil

Abstract

ABSTRACT. We evaluated genetic and environmental factors affecting age at first farrowing of sows in the Brazilian southeast. For this purpose, 466 observations regarding the age at first farrowing were made for Dalland-C40 © animals belonging to two herds. The effects of the environmental factors on this trait were assessed by means of a model that included, as random effects, the influence of the sow's father and mother and, as fixed effects, the influence the year of birth, the herd and the birth season, along with the covariable litter size at birth. The variance components were estimated using the derivative-free restricted maximum likelihood method. The estimated mean was 354.8 ± 25.87 days, with a coefficient of variation of 7.29%. Significant effects on the trait were observed for the herd, the year and the season of birth; Genetic and environment effects on age at first farrowing but a linear effect of litter size at birth on the age at first farrowing was not observed. The boar did not significantly contribute to the variation occurring among the sows, whereas the sow's mother caused significant variation. The heritability estimate for the age at first farrowing was 0.44 ± 0.15, which is considered high. We concluded that herd effect and year and season of birth should be taken into consideration for an accurate genetic comparison; consequently, the animals should be joined into contemporary groups.

Estimation of genetic parameters for reproductive traits in connectedness groups of Duroc, Landrace and Yorkshire pigs in China

“…Our estimates of heritability for AFF were not consistent across breeds and connectedness groups (varied from 0.11 to 0.45). These estimates were in the range of those obtained in previous studies, which ranged from low (0.16) (Serenius et al, ), moderate (0.23) (Akanno et al, ; Knauer, Cassady, Newcom, & See, ) to high (0.44) (Cavalcante‐Neto et al, ). And the standard errors of heritability estimates for AFF in each connectedness group of all breeds were large, implying that the estimates are not reliable.…”

“…Therefore, this variability in calculation for AFF could be or partly due to the small sample sizes (e.g., litters in Group 2–3 of Duroc pigs were <4,000), reflected by the relatively large standard errors (0.12–1.91) and the difficulty of data collecting. AFF can be considered as a comprehensive trait that combines age at first mating and gestation length, the phenotype varied largely in each connectedness group (see Table ) due to environmental factors and measurement error (Cavalcante‐Neto et al, ; Knauer et al, ; Serenius et al, ), resulting in the large variation of estimation of genetic parameters.…”

Genetic Analysis of Major Production and Reproduction Traits of Korean Duroc, Landrace and Yorkshire Pigs

“…For example, in Bísaro pigs, the h 2 of AFF was 0.35 [ 43 ]. With a higher h 2 of 0.44 in sows, Cavalcante-Neto et al [ 44 ] presented further arguments. The h 2 value of 0.23 found by Akanno et al [ 38 ], based on a meta-analysis study, also reported some disagreement.…”