Value of early weight measurements as predictors of body weight at later ages in reindeer

Abstract

Phenotypic variances in live weight in a reindeer population and repeatabilities of the weights were estimated. The population consisted of 1847 and 1878 unselected male and female calves respectively, for which data from weighings at 2 and 7 months of age were available. All individuals in a selected population, consisting of 469 of the heaviest females, were weighed at 2, 7 and 19 months of age. The data were colleted during four successive years, 1986 - 1989. An indirect selection model for improving female weight at 19 months of age was proposed. Variance in the unselected population was higher between animals than within animals. Repeatability was estimated to be 0.636 for the male calves and 0.609 for the female calves. In the selected population, within-individual variance was higher than between-animal variance. Repeatabilities were, after correction for the effect of selection, 0.316 (between 2 and 19 months) and 0.548 (between 7 and 19 months). The aim of the selection model was to increase the average weight in the primiparous group to improve their calf production ability. Using the model, the number of animals weighing equal to or more than a certain threshold weight and the number needed for recruitment at 19 months of age could be determined

Genetic response to selection on reindeer calf weights

“…One hypothetical limitation is that long-term selection based purely on weights may create nutritionally more demanding animals, which suffer more in poor winter conditions. Further, Ropstad et al (1991) have shown that heavy female calves may reproduce prematurely as 1-year-olds and that their development in weight is thereafter retarded. However, such side effects of selection have not been shown in Ruvhten Sijte and should not seriously influence our estimates.…”

“…This paper deals with direct response from selection in calf weights, but indirect benefits of applying the selection programme are not only reflected in calf weights. Retaining heavy calves by selection implies that the physical capacity of animals is improved as the calves grow and become adults (Petersson & Danell, 1993). Improving the condition of the females in a herd may also increase calving rates (Rönnegård et al, 2002), which may be of more economic advantage to the owners than an increase in calf weights alone.…”

“…Earlier published evaluations of reindeer breeding programmes have been limited to investigating effects of herd structure (sex ratio, age structure and weight distribution of adult females) without taking into account inherited effects (Lenvik, 1988;Lenvik, 1990), by making rough estimates of heritabilities in experimental herds (Varo, 1972), or by investigating how calf selection affects weights at older ages (Petersson & Danell, 1993). In these earlier investigations there were no comparisons between different breeding strategies.…”

Conference report (including non-peer reviewed articles) from the 14th Nordic Conference on Reindeer and Reindeer Husbandry Research, 20-22 March 2006, Vantaa, Finland

“…Dette arbeidet var i stor grad inspirert av Lenvik og etterprøvde mange av hans funn. Resultatene fra Ruvhten Sitje bekreftet at høstkalvevektene er en god indikator på ungsimlevektene ved 1,5 års alder (Peterson & Danell, 1993a). Arvegraden for denne egenskapen ble beregnet til rundt 0,4 (Peterson & Danell, 1993b) og stemmer godt overens med Varos (1972) beregninger fra Finland.…”