Influence of Backfat Thickness and the Interval from Altrenogest Withdrawal to Estrus on Reproductive Performance of Gilts

Abstract

Estrus synchronization of gilts can be achieved by feeding the orally active progestogen altrenogest (AT) to cycling gilts at 20 mg/day for 14 to 18 days with gilts usually returning to estrus 4 to 8 days after the last feeding. In practice, gilts failing to exhibit estrus by 6 days after AT withdrawal may compromise weekly breeding targets. The cause of prolonged intervals to estrus are unknown but may involve prolonged suppression due to the release of progesterone (P4), and by extension AT, from adipose tissues. The present study examined relationships between gilt P2 backfat depth (<13.5 mm, 14–16.5 mm, >17 mm groups), the AT withdrawal to estrus interval, and subsequent reproductive performance in gilts. We noted longer intervals to estrus in gilts with greater P2 backfat depths (p < 0.0001), and higher serum P4 concentrations on the last day of AT feeding and at estrus detection (p < 0.05). Total born litter sizes were unaffected by backfat depth, but pigs born alive progressively decreased with increasing backfat depth with the fattest gilts producing the fewest liveborn pigs (p < 0.05). Taken together, these data suggest that adipose tissues may provide a reservoir of steroid, with its release from fatter gilts having potential negative effects on their subsequent reproductive performance.

Effect of Sow Body Weight at First Service on Body Status and Performance during First Parity and Lifetime

“…The results of this study showed that 9% and 14% more sows in the Large and Medium groups compared with the Small group were in estrus within 8 days after synchronization treatment. These results do not agree with those reported by Thitachot et al [ 32 ], who observed longer intervals to estrus in heavier gilts. They explained that the relationship may have been due to a larger reservoir of Altrenogest in the adipose tissue in fatter gilts.…”

Differential Expression Analysis of tRNA-Derived Small RNAs from Subcutaneous Adipose Tissue of Obese and Lean Pigs

“…As an ideal experimental animal model, pigs are widely used in metabolic disease studies of obesity and diabetes [ 3 , 50 ]. However, the fat content of pigs has also been studied as an important economic trait in animal husbandry [ 51 ], and its fat deposition ability will affect pig carcass quality, lean meat rate, and reproductive performance [ 52 , 53 , 54 ]. Therefore, subcutaneous fat thickness is a key indicator for assessing fat deposition in pigs and the reproductive performance of sows, and is regarded as a significant trait in pig breeding.…”