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Whelping series: Nest quality and its effect on the kit survival

Whelping series: Nest quality and its effect on the kit survival

The Mink Visionary

Whelping Series: Nest quality and its effect on the kit survival


Facts instead of opinions

Do you constantly seek to improve yourself and your business? If you do, then we have something in common. We’re happy to share our knowledge with you. Why rely on opinions instead of facts?

This article is based at the results of the master thesis of Christina Dahlin who recently joined our team. 


Why focus on the nest quality?

A good nest before birth has been documented to have a positive effect on the litter size at birth. However, a similar effect has not been seen on the litter size seven days after birth. The aim of this study was to measure the effect of nest quality on kit survival. 


When and how were data collected?

This experiment included 3,351 mated females distributed on four commercial Danish mink farms. The location and quality of nests were scored with points from bad (no hollowing in the nest bottom layer) to good (nest with side walls and the top layer is completely closed). The result of the females’ nest building activity was scored twice: in late gestation and after birth. 


Results

For all four farms, this study showed that both before and after birth the nest building score was significantly lower in groups with access to easy-strø++ compared to straw. Only groups with access to straw were able to build a nest with walls and top. Also, it was found that young females had a lower nest quality before giving birth compared to old females.

But unexpectedly, the quality of the nests before and after birth had no effect on the litter size 1 and 7 days after birth.




Why did this study not find a correlation between nest score and litter size?

One of the reasons could be because the females’ nests in the present study were scored four to seven days earlier (depending on farm) than in the previous study. We know that mink are able to build a good nest in 24 hours. However, in the present study, the females with access to easy-strø++ as nest material were not able to build a nest with top and walls (category score > 3) regardless of the females’ age/parity, or whether nest quality was assessed before or after birth. Furthermore, it has to be taken into account that normal farm procedures were allowed to add extra nesting material when needed. 

The lack of a positive correlation in the present study between the nests scored after birth and the litter size seven days after birth is in accordance with an older study. However, it has to be noted that they did not use straw at the top of the nest boxes, which was used in this present study. A previous study has documented, that a nest box covered with either straw or a wooden board could have a reducing effect on the kit mortality. The study showed that especially first year females seem to benefit from this organization during the first week after birth. 


Our conclusion

Open nests compared to closed nests, scored before birth and after birth, did not differ in the number of kits alive one or seven days after birth. But we advise to have focus on the organization of the nest box environment (for more details see the previous article “The nest box environment”). Depending on the country place either straw or a wooden board in the top of the nest box.


Do you also want to manage your farm by facts instead of opinions? We are the specialists in analyzing and interpreting mink data. Contact us for more details about the master thesis of Christina Dahlin or with other questions (info@ampart.nl) so we can help you.