Nongenetic effects and genetic parameters for length of productive life of Holstein cows in Hokkaido, Japan

Abstract

Records of Holstein dairy cows in Hokkaido, Japan, were used to study the effects of environmental factors on length of productive life and to estimate genetic parameters for length of productive life. Each record was assigned to 1 of 3 data sets depending on the percentage of type-scored cows in the herd. This percentage was considered to partly reflect the management policy in each herd, in particular regarding culling. The A, B, and C data sets consisted of herds with none, less than 60%, and more than 60% of type-scored cows, respectively, and included 158,719, 787,598, and 131,499 records, respectively. Analyses of length of productive life were separately carried out on each data set using the Survival Kit software (Version 5.0). Nonparametric hazards estimates and the shape parameters of the baseline Weibull distribution differed between the 3 data sets. A cow having a sire originating from the United States or Canada had a relatively lower risk of being culled than a cow having Japanese sire in data set C. However, in data set A, a cow having a Canadian sire had a higher relative risk than a cow having a Japanese sire. The herd-year variance for data set A was about twice as large as for data set C. In contrast, the sire variance for data set A was about 40% of the one for data set C. As a result, heritability varied across data sets from 0.046 to 0.134. The results of this study suggest that it is important to consider factors related to herd management policy, such as the percentage of type-scored cows, in genetic analyses on length of productive life of Holstein cows in Hokkaido, Japan.

Genetic analysis of the cumulative pseudo-survival rate during lactation of Holstein cattle in Japan by using random regression models

“…Previous studies have shown that the hazard value during early DIM in each parity was as low as 0.0003 to 0.0005, and increased from 250 to 280 DIM (Ducrocq, 2002(Ducrocq, , 2005Terawaki and Ducrocq, 2009). Similarly, previous studies have revealed that the plot of {ln[− ln(survival function)]} typically shows a mostly linear increase up to 150 DIM, with a more rapid increase thereafter (Roxström et al, 2003;Holtsmark et al, 2009).…”

“…Terawaki and Ducrocq (2009) reported that the ˆ, h s eff 2 obtained using a piecewise Weibull baseline in Holsteins in the Hokkaido region of Japan ranged from 0.046 to 0.134. Moreover, Sasaki et al (2012) reported that the ˆ, h s eff 2 obtained using a unique Weibull baseline in Holsteins in Japan ranged from 0.101 to 0.105.…”

Comparison of piecewise Weibull baseline survival models for estimation of true and functional longevity in Brown cattle raised in small herds

“…Comparing culling risks between lactations, the lowest hazard was found in the first lactation, as in French Holstein (Ducrocq, 2005) and Japanese Holstein cattle (Terawaki et al, 2006;Terawaki and Ducrocq, 2009) using a similar approach. The differences between shape parameters were small for the third and fourth stages, and the two stages could have been merged; however, as the number of records was large enough, five different lactation stages were retained.…”

Changes in the genetic level and the effects of age at first calving and milk production on survival during the first lactation over the last 25 years

“…With a high level of involuntary culling, a farmer has less opportunity to cull low-producing cows voluntarily. In the past, voluntary culling was assumed to be mainly for milk yield, and there is evidence that low-producing cows are more likely to be culled than high-producing cows (Vollema et al, 2000;Sewalem et al, 2005;Terawaki and Ducrocq, 2009). However, in expanding herds in Wisconsin, for low-producing cows the relative risk for culling decreased during the period 1981-2000, whereas the relative risk increased for high-producing cows (Weigel et al, 2003).…”