Age at Puberty in Gilts: Another Important Component of the Herd Reproductive Efficiency Trait Complex
Dr. Pius B. Mwansa
Puberty in gilts is usually defined as the time at which first estrus occurs. Depending on breed, management and season of the year this may occur around 5 to 6 months of age. Estrus or heat may be defined as a period of ovulation during which the female will accept the male. In practice, however, the ultimate indicator of what is regularly referred to as standing heat is the gilt or sow’s immobilization in response to back pressure. It is well known in the swine industry that early attainment of puberty is a key factor in minimizing costs associated with rearing replacement gilts. MacLean et al. (2001) pointed out that when replacement gilts are culled as non-cyclic they accumulate non-productive days that lead to loss of revenue and diminished herd margins. They are true time and feed wasters such that the producer has to factor in these gilts’ costs over the rest of the productive herd. Age at puberty is heritable (29-51%; Donald et al. 1997 & Bidanel et al. 1996) and can respond to genetic selection. Breed differences in age at puberty have been reported (Tummaruk et al. 2008) even though care must be taken when interpreting the differences since many stimulatory or inhibitory factors influence variation in age at puberty. Age at puberty has been reported to have a high genetic correlation (0.84) with weight at puberty (Bidanel et al. 1996). Genomics studies are yielding promising results in identifying SNP or QTL effects associated with variation in age at puberty in gilts (Kuehn et al. 2009; Luckot, 2014). Genesus has invested substantially in R&D geared towards the redesign of the current genetic evaluation program into a modular and more responsive system to incorporation of genomic evaluation approaches. Additionally, Genesus research focused on genetic evaluation of sow productivity traits using genomic approaches is ongoing and expected to be implemented in the near future.