Two schemes of gonadotropin application in sows weaned on day ten postpartum: Effects on reproductive function and efficiency

Abstract

PRIMIPAROUS SOWS WEANED ON DAY 10 POST-FARROWING WERE USED IN TWO EXPERIMENTS DESIGNED TO EVALUATE TWO STRATEGIES OF GONADOTROPIN APPLICATION ON: DURATION OF WEANING-ESTRUS INTERVAL (WEI), DURATION OF ESTRUS (DE), PERCENT OF SOWS IN ESTRUS BEFORE DAY 7 POSTWEANING (EPW), PREGNANCY RATE IN SYNCHRONIZED ESTRUS (PRE), PREGNANCY RATE IN ALL SERVICES (TPR), NUMBER OF PIGLETS BORN ALIVE (PBA), NUMBER OF TOTAL PIGLETS BORN (TPB), NUMBER OF FOLLICLES ON DAY 7 POSTWEANING (SMALL: SF; MEDIUM: MF, AND, LARGE: LF), NUMBER OF CORPORA HEMORRHAGICA (CH), NUMBER OF CORPORA LUTEA (CL), AND NUMBER OF OVULATIONS (ON). TREATMENTS USED IN BOTH EXPERIMENTS WERE: CONTROL (C; SALINE SOLUTION), SIMULTANEOUS GONADOTROPIN (SG; 1 200 UI OF ECG 500 UI OF HCG 24 H POSTWEANING) AND DIFFERED GONADOTROPIN (DG; 1 200 UI OF ECG 24 H POSTWEANING 500 UI OF HCG 96 H POSTWEANING). ESTRUS WAS DETECTED 4 TIMES/DAY, AND BOARS MOUNTED SOWS AT LEAST TWICE. IN EXPERIMENT 1, THE DIAGNOSIS OF PREGNANCY WAS CARRIED OUT ON DAY 35 POSTWEANING (ULTRASOUND). IN EXPERIMENT 2, SOWS WERE SACRIFICED ON DAY 7 POST-SERVICE. REPRODUCTIVE ORGANS WERE COLLECTED FOR COUNTING AND MEASURING OVARIAN STRUCTURES AND FOR PREGNANCY DIAGNOSIS. IN BOTH EXPERIMENTS, PERCENTAGE OF EPW WAS HIGHER IN SG AND DG THAN IN C (SAME ORDER FOR EXPERIMENT 1: 94.7, 90.0, 65.0, AND EXPERIMENT 2: 100, 100, 71.4) WHILE PERCENTAGE OF PRE WAS LOWER IN SG COMPARED WITH DG AND C (EXPERIMENT 1: 50.0, 88.9 AND 84.6, AND EXPERIMENT 2: 12.5, 100 AND 100, RESPECTIVELY). TPR (%) TENDED TO BE HIGHER FOR DG THAN FOR C, AND WAS LOWER IN SG THAN IN THE OTHER TWO GROUPS (RESPECTIVELY FOR EXPERIMENT 1: 80.0, 55.0 AND 47.4; AND EXPERIMENT 2: 100.0, 71.4 AND 12.5). WEI (DAYS) WAS SHORTER IN SG AND DG THAN IN C (EXPERIMENT 1: 5.0, 4.7 AND 7.7, AND EXPERIMENT 2: 5.3, 5.2 AND 7.4). CH NUMBER WAS GREATER FOR DG THAN FOR SG AND C (9.0, 1.8 AND 0.2). ON WAS HIGHER, WHEREAS NUMBER OF MF WAS LOWER IN SG AND DG THAN IN C (ON: 27.7, 35.8 AND 15.3; MF: 0, 0.9 AND 4.6). NUMBERS AND DIAMETER OF LF WERE GREATER IN SG THAN IN DG AND C (10.8, 2.8 AND 0.9 FOLLICLES; 20.5, 8.7 AND 7.5 MM, RESPECTIVELY). NUMBERS OF PBA, TPB, SF AND CL DID NOT DIFFER AMONG GROUPS. SUMMARIZING, RELATIVE TO C, DG AND SG IMPROVED NUMBER OF SOWS IN ESTRUS DURING THE FIRST SEVEN DAYS POSTWEANING BUT SG REDUCED PG, WHEREAS DG DID NOT. THEREFORE, IT IS CONCLUDED THAT DG MIGHT BE USED IN ORDER TO FACILITATE ADOPTION OF EARLY WEANING IN FARMS.