title: Differences during the first lactation between cows cloned by somatic cell nuclear transfer and noncloned cows.
abstract: Lactation performance is dependent on both the genetic characteristics and the environmental conditions surrounding lactating cows. However, individual variations can still be observed within a given breed under similar environmental conditions. The role of the environment between birth and lactation could be better appreciated in cloned cows, which are presumed to be genetically identical, but differences in lactation performance between cloned and noncloned cows first need to be clearly evaluated. Conflicting results have been described in the literature, so our aim was to clarify this situation. Nine cloned Prim' Holstein cows were produced by the transfer of nuclei from a single fibroblast cell line after cell fusion with enucleated oocytes. The cloned cows and 9 noncloned counterparts were raised under similar conditions. Milk production and composition were recorded monthly from calving until 200d in milk. At 67d in milk, biopsies were sampled from the rear quarter of the udder, their mammary epithelial cell content was evaluated, and mammary cell renewal, RNA, and DNA were then analyzed in relevant samples. The results showed that milk production did not differ significantly between cloned and noncloned cows, but milk protein and fat contents were less variable in cloned cows. Furthermore, milk fat yield and contents were lower in cloned cows during early lactation. At around 67 DIM, milk fat and protein yields, as well as milk fat, protein, and lactose contents, were also lower in cloned cows. These lower yields could be linked to the higher apoptotic rate observed in cloned cows. Apoptosis is triggered by insulin-like factor growth binding protein 5 (IGFBP5) and plasminogen activator inhibitor (PAI), which both interact with CSN1S2. During our experiments, CSN1S2 transcript levels were lower in the mammary gland of cloned cows. The mammary cell apoptotic rate observed in cloned cows may have been related to the higher levels of DNA (cytosine-5-)-methyltransferase 1 (DNMT1) transcripts, coding for products that maintain the epigenetic status of cells. We conclude, therefore, that milk production in cloned cows differs slightly from that of noncloned cows. These differences may be due, in part, to a higher incidence of subclinical mastitis. They were associated with differences in cell apoptosis and linked to variations in DNMT1 mRNA. However, milk protein and fat contents were more similar among cloned cows than among noncloned cows.
authors.affiliation: INRA, UMR1313 GABI, F-78350 Jouy-en-Josas, France.
authors.forename: F
authors.initials: F
authors.lastname: Montazer-Torbati
authors.affiliation: INRA, UMR1348 Pegase, F-35590 Saint Gilles, France; Agrocampus Ouest, UMR1348 Pegase, F-35000 Rennes, France.
authors.forename: M
authors.initials: M
authors.lastname: Boutinaud
authors.affiliation: INRA, UMR1313 GABI, F-78350 Jouy-en-Josas, France.
authors.forename: N
authors.initials: N
authors.lastname: Brun
authors.affiliation: INRA, UMR1198 Biologie du Développement et Reproduction, F-78350 Jouy-en-Josas, France.
authors.forename: C
authors.initials: C
authors.lastname: Richard
authors.affiliation: INRA, UE1298 Unité commune d'expérimentation animale, F-78350 Jouy-en-Josas, France.
authors.forename: A
authors.initials: A
authors.lastname: Neveu
authors.affiliation: INRA, UMR1313 GABI, F-78350 Jouy-en-Josas, France.
authors.forename: F
authors.initials: F
authors.lastname: Jaffrézic
authors.affiliation: INRA, UMR1313 GABI, F-78350 Jouy-en-Josas, France.
authors.forename: D
authors.initials: D
authors.lastname: Laloë
authors.affiliation: ALLICE, lieu-dit Le Perroi, F-37380 Nouzilly, France.
authors.forename: D
authors.initials: D
authors.lastname: LeBourhis
authors.affiliation: INRA, UMR1313 GABI, F-78350 Jouy-en-Josas, France.
authors.forename: M
authors.initials: M
authors.lastname: Nguyen
authors.affiliation: INRA, UMR1313 GABI, F-78350 Jouy-en-Josas, France.
authors.forename: S
authors.initials: S
authors.lastname: Chadi
authors.affiliation: INRA, UMR1198 Biologie du Développement et Reproduction, F-78350 Jouy-en-Josas, France.
authors.forename: H
authors.initials: H
authors.lastname: Jammes
authors.affiliation: INRA, UMR1198 Biologie du Développement et Reproduction, F-78350 Jouy-en-Josas, France.
authors.forename: J-P
authors.initials: JP
authors.lastname: Renard
authors.affiliation: INRA, UMR1313 GABI, F-78350 Jouy-en-Josas, France.
authors.forename: S
authors.initials: S
authors.lastname: Chat
authors.affiliation: INRA, UMR1313 GABI, F-78350 Jouy-en-Josas, France.
authors.forename: A
authors.initials: A
authors.lastname: Boukadiri
authors.affiliation: INRA, UMR1313 GABI, F-78350 Jouy-en-Josas, France. Electronic address: eve.devinoy@jouy.inra.fr.
authors.forename: E
authors.initials: E
authors.lastname: Devinoy
mesh_terms: D000818:Animals; D017209:Apoptosis; D002417:Cattle; D002478:Cells, Cultured; D019976:Cloning, Organism; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000235:genetics / Q000378:metabolism; D004041:Dietary Fats / Q000032:analysis; D004624:Embryo Transfer / Q000662:veterinary*; D044127:Epigenesis, Genetic; D005260:Female; D018975:Insulin-Like Growth Factor Binding Protein 5 / Q000235:genetics / Q000378:metabolism; D007774:Lactation; D007785:Lactose / Q000032:analysis; D008321:Mammary Glands, Animal / Q000166:cytology* / Q000378:metabolism; D008892:Milk / Q000737:chemistry / Q000378:metabolism; D008894:Milk Proteins / Q000032:analysis; D015849:Plasminogen Inactivators / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
chemical_list: D004041:Dietary Fats; D018975:Insulin-Like Growth Factor Binding Protein 5; D008894:Milk Proteins; D015849:Plasminogen Inactivators; D012333:RNA, Messenger; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; D007785:Lactose
keywords: DNA (cytosine-5-)-methyltransferase 1 (DNMT1); epigenetics; milk somatic cell counts; subclinical mastitis