Perinatal, neonatal, and rearing period mortality of dairy calves and replacement heifers in France

Abstract

Dairy calf and replacement heifer mortality in France was assessed by calculating mortality rates at 0 to 2d (calves), 3d to 1 mo (calves and heifers), 1 to 6 mo of age, and 6 mo of age to first calving (heifers) using the national identification database. Between birth and 2-d-old, 261,000 and 251,000 of the 3.56 and 3.43 million calves born in 2005 and 2006, respectively, died. The overall 0- to 2-d-old calf mortality rate was around 6.7%, which is similar to the low range of values reported in the literature. Among the 2.38 and 2.39 million calf-month, 139,000 and 133,000 died between 3d and 1 mo of age in 2005 and 2006, respectively. Among the 3d to 1 m of age group, dairy calf mortality rate was around 5.7%. Such a rate has not been reported previously because of the great differences in age classes between studies. For the 0- to 2-d-old and 3-d- to 1-mo-old calves, annual mortality was zero on 26 and 44% of the farms, respectively. Calf mortality during the first month of life increased in winter (to 12-17%) and decreased in summer (to 8-12%), with a small peak in June or July. Mortality during the first month of life is higher in males than in females, with a mortality odds ratio of 1.20 (and 95% confidence interval of 1.19-1.21). Such a difference is also found within the noncrossed or beef-crossed calf subpopulations. Disregarding the sex, the mortality of beef-crossed calves is slightly less than that of noncrossed dairy calves, with a mortality odds ratio of 0.98 (and 95% confidence interval of 0.98-0.99) before 1 mo of age. In heifers, around 51,000, 35,000, and 40,900 out of the 1.2 million 3-d- to 1-mo-old, 1.1 million 1- to 6-mo-old, and 950,000 6-mo-old to first calving heifers died, respectively. The respective mortality rates were 4.5, 3.1, and 4.1%; these rates are similar to the low range of values previously published. The proportions of farms with no heifer mortality during a year were higher than for calves, between 60 and 70%. The mortality probability for heifers was very high for the first day of life (95% survival between 2-30 d of age), then decreased during the first year of life and became constant up to around 3 yr of age (88% survival at 36 mo of age). The risk of mortality is higher in Montbéliarde and Normande heifers compared with Holstein. In conclusion, and beyond the average mortality rates, farmers and farm advisors should keep in mind the broad range of mortality values, which shows that very low mortality (1-2%) can be achieved, even in animals with a known high risk of mortality, such as beef-crossed dairy calves.

Reasons and risk factors for on-farm mortality in Estonian dairy herds

“…These results are similar to that found previously (Svensson et al, 2006;Gulliksen et al, 2009;Torsein et al, 2011;Raboisson et al, 2013) confirming the need for more effective herd health measures to combat these disorders.…”

“…This means that some farms achieve relatively low mortality in calves whereas some herds have very poor calf performance resulting in high mortality. This confirms the results of Raboisson et al (2013) who found high standard deviations for herd level mortality rates and concluded that it is possible for the farmers to achieve very low mortality rates also in animal categories known to have a high risk of mortality. Further studies should clarify the factors that determine the herd performance related with cattle mortality of different age groups.…”

“…We identified a higher mortality among male cattle which can be related to biological features and lower market value (Raboisson et al, 2013;Pannwitz, 2015) and the fact that bull calves do not play a role in dairy herd replacement. The lowest hazard of mortality occurred among heifers aged 12-17 months.…”

“…Most of the studies done in other countries are mainly focused on mortality in certain age-groups (Alvåsen et al, 2014). In addition, mortality can be calculated differently -some studies report mortality risk (Thomsen et al, 2004;Svensson et al, 2006;Raboisson et al, 2013), whereas others calculate mortality rate for different denominator (Raboisson et al, 2011;Perrin et al, 2012;Pannwitz, 2015). Also, registry data misses deaths that occur in the first days of life, since farmers often report calves who died during the first few days and not ear-tagged yet, as stillborn.…”

“…Herd-level risk factors e.g herd size, region, predominant breed in the herd, herd milk yield, grazing, proportion of purchased animals have shown to influence dairy cow mortality Burow et al, 2011;Raboisson et al, 2011;Alvåsen et al, 2012). Some examples of animal level risk factors associated with calf and youngstock mortality are breed, gestation length, parity of the dam, dystocia, being born as a twin or triplet, congenital defects, calving season, sex and weight of the calf, respiratory disease, diarrhea and arthritis (Svensson et al, 2006;Gulliksen et al, 2009;Bleul, 2011;Raboisson et al, 2013). Few examples of herd-level risk factors for calf mortality are herd size, characteristics of calving stall, suckling as feeding regimen and housing system from 2 weeks of age (Gulliksen et al, 2009).…”