(Walker et al., 2007). For goats, there were no published studies or other data on compositional data on milk and meat.
Food safety assessment of cattle clones and their progeny
When it comes to cattle, the FDA-reviewed data on milk composition from clones vs non-clones come from only seven peer-reviewed studies that collectively involved 43 animals. Of these seven studies, only 2 of them involved appropriate controls. Heyman et al. (2004) found that first lactation milk yields and somatic cell counts (SCC, which are a measure of milk quality; extremely high counts indicate udder infections) for three Holstein clones were similar to those of age-matched non-clone comparators raised under similar condition. Although the mean SCC didn’t differ between clones and non-clones, the variability in SCC was more than twice as large for the clones compared to the non- clone comparators, which is just the reverse of what one would expect. Tian et al. (2005) compared the milk from a single lactation cycle of only four Holstein clones to the milk from four Holsteins of the same age and parity that lived in the same facility from 2 months of age and received the same diets and management practices; such controls were designed to reduce variation and facilitate comparison. There were no significant differences in the various milk parameters looked at (total fat, total protein, total solids, lactose, non-urea nitrogen, somatic cell counts); although the differences in somatic cells counts (SCC) was not statistically significant, SCC of clones was about 10% higher than non-clone comparators.
The other five studies really did not use appropriate controls. A study involving 15 dairy cow clones of three different breeds (12 Holsteins, 1 Brown Swiss and 2 HolsteinXJersey [Holstein Jersey cross]), produced by Infigen, Inc., used comparator animals of approximately the same age and lactational stage, but the comparator cows were housed on different farms and so were fed different rations than the clones; in addition the ration for the clones changed during the course of the lactation (Walsh et al. 2003). Walsh et al. (2003) found differences in the fatty acid profiles of the milk over the course of the lactation, with the differences in palmitic acid and linolenic acid being statistically significant. In addition, there were statistically significant differences in levels of potassium, zinc, strontium, and phosphorous. However, the authors chalked up these statistically significant differences to differences in diet, concluding that there were no “obvious differences between milk from clones and non-clones” (Walsh et al., 2003: 213). Given the fact that clones and comparators were not raised on different farms and received different diets makes this a poorly designed study that makes the results very hard to interpret.
Three of the milk composition studies were carried out in Japan. Two of these studies involved comparing milk of clones to that of the donor animal from which the clone was derived (Aoki et al., 2003; Yonai et al., 2005); this makes a statistical evaluation virtually impossible. The third Japanese study is a report, “Investigations on the Attributes of Cloned Bovine Products” published by the Japan Livestock Technology