Quality and safety of bovine clones and their products

Abstract

A multidisciplinary research programme was developed to get a scientific expertise for the quality assessment of products obtained from cloned livestock. Thirty-seven bovine Holstein female clones of five different genotypes and their products were analysed in comparison with 38 control animals obtained by conventional artificial insemination and raised under the same conditions at the same experimental farm. Animal evaluation included over 150 criteria and more than 10 000 measurements to check the physiological status and health over a 3-year period. All the parameters studied were in the normal range for age and breed, but some significant differences were detected between clone and control groups in terms of delayed onset of puberty in clones, higher neutrophil counts in haematology or lower biochemical plasma concentrations of gamma glutamyl transferase. Milk and meat analyses were conformable to expected values. We, however, found some differences in fatty acid (FA) composition of milk and muscle suggesting a possible deviation in lipid metabolism as assessed by higher delta-9 desaturase activity indexes in both milk and muscles from clones compared with controls. Repeated muscle biopsies in the semitendinosus muscle of the same animals demonstrated a higher oxidative activity in muscle of young clones (8 months of age) compared with controls, suggesting a delayed muscle maturation in clones. Nutritional evaluation of milk and meat using the rat feeding trials did not show any difference between clone and control products for food intake, growth rate, body composition of the rats, nor for possible allergenicity. Possible reactivation of bovine endogenous retroviruses (BERVs) was analysed and compared between normal and cloned cattle. As expected, these BERV sequences are not transcribed and no RNA was detected in the blood of clones, donor animals or controls; therefore, it may be assumed that the sanitary risk associated with BERV sequences is not higher in cattle derived from somatic nuclear transfer than in cattle born from conventional reproduction. Our results confirm that the quality and safety of products (milk and meat) from adult and clinically healthy cloned cattle is globally similar to normal animals. However, from a strictly biological point of view, the slightly delayed maturation we observed in the muscle of clones together with some marginal differences identified in FA composition of both muscle and milk, point to the need for more refined analysis to totally exclude any risks from the consumption of those products.

Comparison of cloned and non-cloned Holstein heifers in muscle contractile and metabolic characteristics

“…In addition, changes in MyHC isoforms with age for control heifers were accompanied by changes in the LDH/ICDH ratio (which decreased) and COX and HAD enzyme activities (which increased between 8 and 24 months of age). The respective results for LDH and ICDH activities were published previously (Heyman et al, 2007b). The ICDH activity was significantly higher (1110%, P , 0.001) in the muscle of clones than in controls at 8 months of age.…”

“…One unit of the enzyme was defined as the amount that catalyses per min the disappearance of 1 mmol of nicotinamide adenine dinucleotide (NADH) reduced form for LDH and HAD, the reduction of 1 mmol of NADP for ICDH and the oxidation of 1 mmol of cytochrome-c for COX. The respective results for LDH and ICDH activities are already published (Heyman et al, 2007b); so in the present paper, an LDH/ICDH ratio is reported as an indicator of any modification in muscle metabolic activity since this ratio is more sensitive to physiological changes than the absolute enzyme activities. The results are expressed in mmol/min per g of muscle for COX and HAD activities.…”

“…No differences in FA composition were observed in the muscle of clones at later stages (Berthelot et al, 2004). In addition to these putative delays in muscle maturity in cloned heifers, Heyman et al (2007b) also reported a delay in sexual maturation for the onset of puberty, suggesting that not only muscle biology is affected.…”

“…The muscle biopsy samples on the cloned and control heifers of this study have also been used to compare FA composition (Berthelot et al, 2004;Heyman et al, 2007b). Interestingly, several differences were observed between cloned and control heifers at 8 months of age.…”

“…The present paper is consistent with a multidisciplinary approach to establish scientific expertise on clones and their milk and meat products (Heyman et al, 2007a and2007b) and aims to compare the evolution of muscle contractile and metabolic characteristics from cloned and control Holstein heifers at different ages.…”