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Whelping Series: the nest box environment

Whelping Series: the nest box environment

The Mink Visionary

Whelping Series: the nest box environment


Facts instead of opinions

Do you constantly seek to improve yourself and your business? If you do, then we have something in common. 

We will present you a series of articles based on analysis from Christina’s master thesis. The aim of the study was to investigate how both feeding strategy in the late gestation and the nest box environment could contribute to the improve the female’s ability to perform early maternal care and thereby an increased kit survival. 

In this article, we’re going to present how the nest box environment can affect the female’s ability to perform early maternal care. 

We’re happy to share our knowledge with you. Why rely on opinions instead of facts?


Why focus on the first seven days after birth?

Video monitoring in the nests of females documented an average litter size of 9.6 kits at birth. On average 7.0 kits were alive one day after birth, and 6.2 of the kits being alive one week after birth. Hence, there is a potential to improve the kit survival by optimizing the management around birth.


Types of nest box insertion and nest material

A nest box insertion in the nest can help the female keeping the kits together and thereby reduce early kit mortality, and furthermore contribute to establish a good temperature in the nest. Likewise, there are many different materials that the farmers can offer the female for nesting. The nest materials physical abilities are different ex. according to structure, isolation, and the optimal amount as well as composition.

It has been documented that the combination of easy-brick and straw has a positive effect on the kit survival seven days postpartum compared to the combination of stone brick and straw. Furthermore, it has been documented that easy-brick and stone brick have the same reducing effect on the kit mortality from birth to seven days after birth when combined with either straw+lamb wool, or easy-strø+ (consisting of hemp and finely chopped straw). The reason for this reduced kit mortality in the groups with combined nest materials could be because stone brick did not have the same hypothermic effect on the kits as when only straw was used as nest material.


Experimental design

This Danish farm experiment included 3,351 mated mink females distributed on four commercial farms. The experimental period began in the middle of April and ended when the kits had the age of seven days. On each of the four farms, the mated females were grouped in three main groups with 256-303 mated females (depending on farm).



No differences in kit survival between easy-brick and stone brick were found 

The analysis of the nest box insertions effect on kit survival one to seven days postpartum was compared between the main groups; control and easy-brick. There was no proven difference in the kit survival from day one to day seven postpartum when the nest box consisted of either an easy-brick as nest insertion or a stone brick.


One of the reasons that no differences were found between easy-brick and stone brick, could be because that more of the breeders in the present study remarked that the allocated easy-brick did not dilate sufficiently to be fixed in the nest box, as it usually does. When easy-brick not is fixed in the nest box, it can be difficult for the female to keep the kits together which can cause the kits to be squeezed or the kits to be placed on both sides of the easy-brick. 

Furthermore, only first year females were used in the previous study and these females had no extra help for the kits (e.g. transferring kits between females or the use of incubator). In this study, the breeders actively make an effort to rescue kits, and 39.9% of the females in the present study had the age of two to four years. 

Moreover, this study documented that easy-brick and stone brick had the same reducing effect on the kit mortality on the farms with a combination of either straw and easy-strø or straw and sand as nest materials.


Stone brick as nest insertion and easy-strø++ as nest material.



No differences in kit survival between easy-strø++ and straw as nest material were found 

The main groups, control and easy-strø++, were compared in the analysis of the nest material and their effect on the kit survival from day 1 to day 7 postpartum. In the group with easy-strø++, there was a significantly larger total count of kits one day postpartum (included dead and kits alive). However, no differences were documented between the number of kits alive day 1 and day 7 postpartum. Furthermore, there was no significantly increased probability for the kits to die one to seven days postpartum in nests with straw compared to nests with easy-strø++. 


One of the reasons that no differences were found between easy-strø++ and straw, could be because different types and combinations of nest material(s) had been used, as straw and sand, easy-strø++ and sand, only straw, straw and easy-strø. Thereby, the nests across farms were not directly comparable. 

 

Nest with easy-strø++ as nest material and stone brick as nest insertion.


Nest with straw as nest material and stone brick as nest insertion.



Our conclusion

We advise to add a finely chopped nest material to the bottom of the nest box as easy-strø, wood shavings or sand. In this way, the female has a good ground to build up a nest. Additionally, add straw to the nest box/cage and supplement with straw in the cage. Depending on the country place straw in the top of the nest box.

Examples of nest box environments: 



Next series: Nest quality and its effect on the kit survival.

In our next whelping series, we will present how the nests quality before and after birth effect the early kit survival.

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 (info@ampart.nl) so we can help you.