Growth, Reproduction, and Lactation in Somatic Cell Cloned Cows with Short Telomeres

We previously showed that telomere lengths of 10 somatic cell cloned cows were significantly shorter than normal. In this study, we investigated growth, reproduction, and lactation in these animals to determine if shortened telomeres have any effect on these characteristics. Six Holstein and 4 Jersey cloned cows, derived from oviduct cells, were reared under general group feeding. Body weights were recorded from birth to 48 mo of age. A number of reproductive characteristics were screened during the prepubertal, postpubertal, and postpartum periods. After parturition, milk yields were recorded daily and percentages of milk fat, proteins, and solids-not-fat were measured at monthly intervals. These data were used to estimate production of milk components over a 305-d period. Overall, the cloned heifers exceeded standard growth rates for each breed. The cows were inseminated at the first estrus after they reached 450 d of age, and delivered normal calves except for one stillbirth in the Holstein group. They were inseminated at postpartum estrus to provide second and third parturitions and, again, these pregnancies were normal. Gestational periods and birth weights of the calves were both within the normal range. The average total milk yield per cow in Holstein group clones was less than that of the original cow, whereas Jersey group clones showed a higher average milk yield than the original cow. In both groups of cloned cows, inter-individual variation in milk production was relatively large; however, the coefficient of variation was less than 10%. Our results suggest that the cloned cows have normal growth, reproductive, and lactation characteristics, and thus normal productivity, despite having reduced telomere lengths.