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Yearling mink dams fed restricted in early lactation have less mammary gland tissue six weeks after birth

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The optimal timing of separating the mink dam from the litter is suggested to be a balance between the partly conflicting needs of the mother and the kits. Early removal of the dam or partial removal of the litter may protect the dam against exhaustion. Little is known about the maternal motivation around the time of separation. Therefore, we investigated the effects of separating the dam from the litter, using brown first-parity dams (N=374) randomly assigned within each date of delivery to two treatment groups: The dam was taken away from the litter either at day 49 ±1 (7w, N=185) or at day 56 ±1 (8w, N=189) after birth. The aim was to investigate whether the dams had a different motivation to take care of the litter after 7 and 8 weeks, estimated by non-invasive determination of cortisol (FCM: Faecal Corticsol Metabolites) and dam calls the first week after separation. The two treatment groups had an equal litter size at the time of separation (age 7w: 5.5 ±0.17; 8w: 5.5 ±0.17 kits; range 1-11; P=0.76). Likewise, there was no significant difference in dam body weight (7w: 1420 ±15.0 g, 8w: 1404 ±14.7 g; range 930-1680 g, P=0.43). However, the litter size negatively influenced both the dam weight and her BCS (P<0.001) regardless of the separation age. Dams separated at the litter age of 7 weeks had higher concentrations of cortisol during the first week after removal (day of separation, D0: 18.8%, D1: 34.5%, D7: 36.9% higher FCM) than dams separated at the litter age of 8 weeks (P=0.014). Likewise, the dam calls increased on the separation day, peaking on the first day after separation (D1). The proportion of dams with calls decreased with litter age at separation (P=0.024). We interpret these results as a higher maternal motivation in dams at 7 weeks than at 8 weeks after delivery. Additionally, the amount of dam calls after separation decreased with the litter size (P=0.022). Thus in addition to litter age, the size of the litter is important for the maternal motivation. These factors should, therefore, be taken into account in studies of the optimal separation age in mink.
OriginalsprogEngelsk
TitelProceedings - NJF Seminar 485 - Autumn Meeting in Fur Animal Research 2015
Udgivelsesårsep. 2015
Sider104-112
StatusUdgivet - sep. 2015
BegivenhedNJF seminar 485 - 2015: The effect of nest box climate on kit growth rate and survival in the American mink (Neovison vison) - Hamburger Börs, Turku, Finland
Varighed: 29 sep. 20151 okt. 2015

Konference

KonferenceNJF seminar 485 - 2015
LokationHamburger Börs
LandFinland
ByTurku
Periode29/09/201501/10/2015

Bibliografisk note

projekt - afventer SHM

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