Effects of age and growth rate at onset of boar exposure on oestrus manifestation and first farrowing performance of Landrace×large white gilts

Abstract

a b s t r a c tThe objective of this study was to evaluate the effects of age and growth rate until the onset of boar exposure on oestrus manifestation and reproductive performance in Landrace  large white crossbred gilts (DanBred). Gilts were retrospectively classified into groups according to age at boar exposure -BE (140-155 and 156-170 days) and in three classes of growth rate (GR) at BE (low GR: 500-575 g/d; intermediate GR: 580-625 g/d; and high GR: 630-790 g/d). Overall, gilts had an average weight of 105.470.53 kg and age of 170.670.41 days at their first oestrus. There was no significant effect of age  GR interaction (P40.05) on weight and age at first oestrus, interval between boar exposure and oestrus (BEOI), and percentages of gilts showing oestrus. Gilts exposed at 140-155 days of age showed oestrus at a lower age (167.670.76 vs. 173.770.73 days) but with similar BEOI (15.170.75 vs. 14.270.73 days) and weight (104.771.04 vs. 105.571.00 kg) compared with gilts exposed at 156-170 days (Po0.05). Gilts exposed to boar at 140-155 days had lower oestrus manifestation (60.8% vs. 77.0%) within 30 days than those exposed at 156-170 days of age. High GR gilts showed the first oestrus at a lower age (169.370.78 vs. 172.170.82 days of age) and had a shorter BEOI (13.570.77 vs. 16.070.81 days) than low GR gilts (Po0.05). Lower percentages of gilts in oestrus within 30 days after BE (Po0.05) were observed in low GR and intermediate GR gilts (65.5 and 64.3%) than in high GR gilts (74.3%). Farrowing rate and number of total born piglets were neither affected by age and GR at onset of boar exposure nor by their interaction (P40.05). In conclusion, first oestrus manifestation is greater when gilts are exposed to boars after 155 days of age or with a GR4625 g/d. Provided that gilts are bred with a minimum of 130 kg, the reproductive performance is not affected by age or GR at boar exposure.

Evaluation of gonadal macroscopic and microscopic morphometry reveals precocious puberty in Bísaro pig

“…An overall picture of these correlations shows that great part of the dispersion of values is due to inter‐herd variance. Variance between individuals from the same breed, reflect farm management, diet composition and ultimately the animal body growth (Magnabosco et al., 2014). Therefore, additional samples from different farms would have benefited the study, and hence the prediction model.…”

Gilt Management for Fertility and Longevity

“…The ability to identify early puberty, and to produce a synchronous pubertal response to external stimuli, are both dependent on the age at the start of puberty stimulation and heat detection. When boar exposure commences earlier (140 to 160 d of age), a normal distribution in age at detected first estrus is observed in the majority of the population [56,62,63]. When gilts continue to be stimulated and monitored for longer periods (up to 260 days of age), most will eventually have a recorded estrus, however, the later maturing gilts were reported to be part of a different distribution [63].…”

“…Beltranena et al [71] suggested that at growth rates below 0.55 kg/d the onset of puberty may be delayed. More recently, the negative relationship between age and lifetime growth rate at puberty has been confirmed [50,62,72]. Given the growth rates achieved in contemporary dam-line genotypes, few gilts are at risk of low growth rates (>0.55 kg/d), however, puberty onset will still be delayed in slower growing gilts [63].…”

The replacement gilt: Current strategies for improvement of the breeding herd

“…The stimulation should be started around 140 days of age because age at puberty has been shown to be associated with age at onset of boar exposure. 110 On the other hand, van Wettere et al 42 suggested that first boar exposure should be delayed until 182 days of age because greater synchrony occurred within gilt groups. After stimulation, gilts achieved first estrus sooner and consequently their lifetime productivity was greater.…”