Relationship Between Type Traits and Longevity in Canadian Jerseys and Ayrshires Using a Weibull Proportional Hazards Model

Abstract

The aim of this study was to use a Weibull proportional hazards model to explore the impact of type traits on the functional survival of Canadian Jersey and Ayrshire cows. The data set consisted of 49,791 registered Jersey cows from 900 herds calving from 1985 to 2003. The corresponding figures for Ayrshire were 77,109 cows and 921 herds. Functional survival was defined as the number of days from first calving to culling, death, or censoring. Type information consisted of phenotypic type scores for 8 composite traits and 19 linear descriptive traits. The statistical model included the effects of stage of lactation; season of production; annual change in herd size; type of milk recording supervision; age at first calving; effects of milk, fat, and protein yields calculated as within herd-year-parity deviations; herd-year-season of calving; each type trait; and the animal's sire. Analysis was done one trait at a time for each of 27 type traits in each breed. The relative culling risk was calculated for animals in each class after accounting for the previously mentioned effects. Among the composite type traits with the greatest contribution to the likelihood function was final score followed by mammary system for Jersey breed, while in Ayrshire breed feet and legs was the second most important trait next to final score. Cows classified as Poor for final score in both breeds were >5 times more likely to be culled compared with the cows classified as Good Plus. In both breeds, cows classified as Poor for feet and legs were 5 times more likely to be culled than were cows classified as Excellent, and cows classified as Excellent for mammary system were >9 times more likely to survive than were cows classified as Poor.

Genetic correlations between production and disease traits during first lactation in Holstein cows

“…Therefore, selection indices in many countries place positive weight on health traits or healthrelated traits (Miglior et al, 2005). When health trait data are not available in routine genetic evaluations, genetic performance for disease resistance can be improved by indirect selection using health-related traits such as SCS or type traits (Lund et al, 1999;Sewalem et al, 2005).…”

Genetic Prediction Models and Heritability Estimates for Functional Longevity in Dairy Cattle

“…Udder depth has been reported to have the highest relative contribution to survival likelihood, and therefore had the highest effect on cow survival after correction for milk production (Bünger & Swalve, 1999;Caraviello et al, 2003;Zavadilová et al, 2011). Dadpasand et al (2008), Sewalem et al (2005a) and Caraviello et al (2003;2004b) reported an intermediate optimum for udder depth, implying that cows with very deep or very shallow udders were at high risk of being culled from the herds. Among US Jersey cows, udder depth scores of between 6 and 10 on a scale of 1 to 100 had 1.60 times more relative risk of involuntary culling than cows with scores between 21 and 25, while cows with udder depth scores of 41 to 45 had a relative risk of 0.70 times that of cows with scores of 21 to 25 .…”

“…Survival in a given lactation was coded 1 if the cow survived during that lactation; and 0 if the cow was culled during that lactation or if the number of days between the current calving and extraction date exceeded 581. Sewalem et al (2005a; defined the length of productive life as time in days from one calving to the next calving, death or culling. Holtsmark et al (2009) expressed longevity variously as herd life in the first lactation, calculated as number of days from calving to culling, censoring or second calving; and as herd life in the first five lactations, calculated as number of days from first calving to culling, death, censoring or sixth calving.…”

“…This entails the inclusion of all economically relevant traits in the breeding objective. Traits such as longevity, cow fertility, udder health and functional efficiency have increasingly become important in national selection objectives, which were previously based on milk and component production traits alone (Carlén et al, 2005;Miglior et al, 2005;Sewalem et al, 2005a). The breeding objective for South African Holstein cattle has already incorporated calving interval and somatic cell count (Banga, 2009).…”

Genetic parameters estimates for locomotion score, body condition score and final type score of Holstein cattle in southern China

“…Body condition score (BCS) as a determinant for the nutritional needs in the past was also reported to play a very important role in milk production (Wildman et al 1982) and reproduction (Pryce et al 2001). Final type score (FTS) has a strong relationship with functional survival of dairy cattle (Sewalem et al 2004(Sewalem et al , 2005, so it is also a very important trait involved in dairy cattle breeding and selection programme. Recently, both LS and BCS are considered as new traits in type classification (WHFF 2005).…”