Avaliação da ordem de parição na espessura de toucinho, escore corporal e índices reprodutivos de fêmeas suínas

Abstract

This study aimed to evaluate the effect of parity order (PO) of sows raised on a commercial farm on backfat thickness (BT), body condition score (BCS), and reproductive indexes measured in females. PO categorized one hundred and eighty-two females as primiparous (PO1), secondary-headed (PO2), 3rd to 6th gestation (PO3, PO4, PO5, and PO6), respectively, and with more than six pregnancies (PO>6). About 728 backfat thickness records were measured by ultrasound (BTU) and body condition score by visual assessment (BCV) and caliper (BCC) at four physiological moments (PM) of the females: during pre-breeding, at the transfer of the females to the collective pens (30 days of gestation) and farrowing room (107 days of gestation), and weaning, considering five groups of approximately 36.4 females. Mixed linear models were adjusted to the data of the dependent variables considering three different scenarios: 1) Fixed effects model containing PO, PM, the interaction between PO and PM, group of matrices (GM), age of the matrices (AM), and environmental variables mean temperature, temperature range, mean relative humidity and relative humidity range, measured in the periods before the measurements of BT and BCS; 2) Mixed model with fixed PO, PM, and PO × PM, random and classificatory GM, and AM and other random and numerical environmental variables; 3) Previous mixed model plus matrix number, classificatory, in the random part. There was an effect (P < 0.05) of PO × PM in the BCS and BTU and of increasing PM up to PM107 in the BCV, BCC, and BTU. These results occurred because the sows went through different gestational phases, first seeking to recover the losses that occurred during lactation, then in the growth to the subsequent pregnancy, and later in the development of the piglets and the mammary system. There was an effect (P = 0.0193) of PO on the prepartum weight (PPW) of the sows, in which females with six pregnancies had higher PPW than primiparous females. There was no difference (P > 0.05) in the body condition of the sows (BCV and BCC) and in the BTU between the different POs, which justifies the similar results (P > 0.05) in the number of piglets born total, alive, dead and mummified, and in the number of piglets weaned between PO5 sows and sixth gestation sows (PO6), which can be kept in the breeding stock. Females with more than six pregnancies have lower backfat thickness than females with up to three pregnancies in the prebreeding period and females with up to five pregnancies in the post-weaning period. Thus, they should be discarded to maintain the productive efficiency of the breeding stock.