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. 2008. Effects of dietary energy and lysine intake during late gestation and lactation on blood metabolites, hormones, milk composition and reproductive performance in primiparous sows. Can. J. Anim. Sci. 88: 247Á255. The effects of energy and lysine intake during late gestation and lactation on the reproductive performance of primiparous sows were evaluated using 36 gilts. Sows were allocated to six dietary treatments according to a 3 )2 factorial arrangement and each treatment had six replicates. Three energy levels [low (EL), medium (EM) and high (EH)] and two lysine levels [low (LL) and high (HL)] were used. Gilts with HL intake had more weight (P00.004) and backfat thickness (P00.047) gain during gestation. Similar changes in sow body conditions were observed during lactation. HL intake resulted in higher litter birth weight (P00.001), weaning weight (P00.001) and growth rate (P B0.001) and shortened wean-to-estrus interval (P00.001). Energy intake influenced the fat and lactose content while lysine intake influenced the total solids and protein content in milk and colostrum. Gilts with HL had higher insulin and lower creatinine levels during postfarrowing and weaning, while triglyceride concentration at weaning increased with increasing of energy intake. The basal and pulses of LH were also influenced by lysine intake. In conclusion, higher lysine intake than those recommended by National Research Council (1998) could improve performance during late gestation and lactation in primiparous sows.Key words: Energy, lysine, gestation, lactation, sows Heo, S., Yang, Y. X., Jin, Z., Park, M. S., Yang, B. K. et Chae, B. J. 2008. Incidence de la quantite´d'e´nergie alimentaire et de lysine inge´re´e a`la fin de la gestation et durant la lactation sur la concentration des me´tabolites du sang et des hormones, sur la composition du lait et sur les aptitudes a`la reproduction des truies primipares. Can. J. Anim. Sci. 88: 247Á255. Les auteurs ont e´value´l'incidence de la quantite´d'e´nergie et de lysine absorbe´e a`la fin de la gestation et durant la lactation sur les aptitudes a`la reproduction de 36 truies nullipares. Les animaux ont e´te´re´partis entre six rations selon une disposition factorielle de 3)2, chaque traitement faisant l'objet de 6 re´pe´titions. Les auteurs ont recouru a`trois concentrations d'e´nergie (EL, EM et EH) et deux de lysine (LL et HL). Les cochettes recevant la ration HL ont pris plus de poids (P0 0,004) et leur gras dorsal e´tait plus e´pais (P00,047) durant la gestation. Les auteurs ont observe´des changements analogues chez les truies pendant la lactation. Le re´gime HL entraıˆne la naissance de porcelets plus lourds (P00,001), au poids plus e´leve´au sevrage (P00,001) et au taux de croissance plus rapide (PB0,001) ainsi qu'un raccourcissement de l'intervalle entre le sevrage et l'oestrus (P 00,001). L'ingestion d'e´nergie agit sur la concentration de lipides et de lactose alors que celle de lysine modifie la concentration de solides totaux et de prote´ines dans le lait et le colostrum....

This study was conducted to investigate the effect of recipient activation time on the chromatin structure and development of bovine nuclear transfer embryos. Serum-starved skin cells were electrofused to enucleated oocytes, activated 1-5 hr after fusion, and cultured in vitro. Some fused eggs were fixed at each time point after fusion without activation, or 3 or 7 hr after activation. Some nocodazole treated zygotes were fixed to analyze their chromosome constitutions. The proportion of eggs with a morphologically normal premature chromosome condensation (PCC) state increased 1-2 hr after fusion. Whereas eggs with elongated chromosome plate increased as activation time was prolonged to 3 hr, and 5 hr after fusion, 58.1% of eggs showed more than two scattered chromosome sets. The proportion of eggs with a single chromatin mass (40.6-56.7%) significantly increased when eggs were activated within 2.5 hr after fusion (P < 0.05). Only 23.3% of reconstituted embryos activated 5 hr after fusion formed one pronucleus-like structure (PN), whereas, 64.5-78.3% of embryos activated 1-2.5 hr after fusion formed one PN. The proportion of embryos with normal chromosome constitutions decreased as activation time was prolonged. Development rates to the blastocyst stage were higher in eggs activated within 2 hr after fusion (17.3-21.7%) compared to those of others (0-8.6%, P < 0.05). The result of the present study suggests that activation time can affect the chromatin structure and in vitro development of bovine nuclear transfer embryos.