A registry-based study of declined foaling rates in Finnhorses

Tiina Reilas,Anna-Maija Virtala,Mikko Kosola,Terttu Katila

doi:10.23986/afsci.89440

Abstract

In Finland, the seasonal foaling rates of trotters began declining at the beginning of the 2000s. This retrospective study aimed to elaborate factors behind the declining foaling rates in Finnhorses using multivariable logit models. The mating records from years 1998 to 2000 (period 1, n = 5967) and 2002 to 2004 (period 2, n = 5373) originated from the Finnish trotting and breeding association. The over-all foaling rate was 66.6% during period 1 and 62.4% during period 2 (p < 0.0001). Foaling rate for on-site artificial insemination decreased from 70.2% to 64.8% (p = 0.003). The proportion of the most fertile mare groups, 2–9-year-olds and foaled mares, decreased by 8.2 and 7.1 percentage points, respectively. Differences in foaling rates between young and middle-aged mares, and maiden and foaled mares changed from non-significant to significant (p<0.0001) due to the foaling rate decline in middle-aged (p = 0.001) and maiden mares (p = 0.01). The decline in foaling rate was also significant for barren and rested mares (p < 0.05), natural mating (p = 0.01), and book size >68 (p < 0.0001). It was concluded that multiple factors were responsible for the foaling rate decline.

Highlights

In Finland, the 21st century began with declining seasonal foaling rates for Finnhorses and Standardbreds, the two main trotting breeds in the country (Katila et al 2010)
We expected to see interactions between mare age and reproductive status, and between mating type and book size, but we found interactions only between the last two
The foaling rates in all groups were lower in period 2, but the decrease was more pronounced in middle-aged mares (5.6 %-points), maiden mares (5.6 %-points), mares inseminated on-site (5.4 %-points) or mated naturally (5.0 %-points), and if stallions with a highest book size were used (6.7 %-points) (Table 1)

Summary

Introduction

In Finland, the 21st century began with declining seasonal foaling rates for Finnhorses and Standardbreds, the two main trotting breeds in the country (Katila et al 2010). Seasonal foaling rates in Finland increased in the 1980s because of better management and new reproductive technologies, artificial insemination (AI) and ultrasonography (Katila et al 2010). After a plateau in the 1990s, foaling rates began decreasing (Hippos 2018a, 2018b). The Finnhorse is the only native horse breed in Finland. Low foaling rates raise particular concern because, with a few exceptions, Finnhorses only exist in Finland, and the number of foals born per year decreased to less than 1000 in 2015 (Hippos 2017)

Methods

Results

Discussion

Conclusion