Parturient behaviour in farmed mink (Mustela vison) in relation to early kit mortality

Abstract

Abstract Litter size and kit mortality are both relatively high in the production of farm mink, with the vast majority of deaths occurring around parturition and during the first days of life. Maternal care is crucial to ensure the survival of the vulnerable kits. This subject has received little attention and the objective of the present study was to describe periparturient behaviour and the course of parturition in mink, aiming to identify key factors related to early kit mortality. We video recorded the parturitions of 39 1-year-old primiparious mink dams of the brown colour-type ‘wild’ kept under identical conditions, and sampled data on the progress of parturition for descriptive analysis. In addition, a detailed behavioural analysis was performed on a subset of the sample comparing low mortality (‘SURV’, n = 8) and high mortality (‘MORT’, n = 8) females with equally sized litters. MORT females lost more than 70% of their live-born kits from the day of parturition (Day 0) until Day 7, whereas SURV females lost none. Several types of behaviour in mink females around parturition are described for the first time. SURV females spent more time in kit-directed behaviour, such as circling, carrying, sniffing/licking the kit, and moving the kit to the udder, and kits from their litters were alone for shorter periods during the first 24 h after the birth of the first kit compared to MORT dams. The majority of kit deaths occurred during the first day postpartum, and deliveries with high variation in inter-birth intervals were related to increased kit mortality ( P = 0.025). MORT females spent more time sniffing/licking their genital region prior to parturition ( P = 0.004). The duration of parturition was markedly longer in MORT than in SURV dams (607 (125) min versus 309 (72) min, P = 0.034). The inter-birth intervals increased as parturition progressed ( P = 0.032), with different level (MORT > SURV, P = 0.002), but the same slope (N.S.), for SURV and MORT litters. In conclusion, our results point to birth problems as important contributors to suboptimal maternal behaviour and early kit mortality in farmed mink.