Determination of energy and protein requirement for maintenance and growth and evaluation for the effects of gender upon nutrient requirement in Dorper × Hu Crossbred Lambs.

This study aimed to determine energy and protein requirement of Dorper × Hu crossbred lambs and further to evaluate the effect of gender upon nutrient requirement parameters. Forty-two female lambs (18.60 ± 1.57 kg) and 42 male lambs (18.30 ± 1.28 kg) were used. In comparative slaughter trial, 30 of animals from each gender group were randomly selected and assigned to ad libitum (AL), low restriction (LR) and high restriction (HR) group, and then were slaughtered when lambs under AL treatment reached target BW of 20, 28, and 35 kg, to determine body energy and nitrogen retained. In digestibility trial, remaining 12 female (18.01 ± 1.66 kg) and 12 male lambs (18.43 ± 1.17 kg) were randomly assigned to three feeding treatments in accordance with the design of comparative slaughter trial, to evaluate dietary energetic values at different feed intake levels. The combined data indicated that metabolizable energy (ME) requirement for maintenance (MEm; 400.61 ± 20.31 vs. 427.24 ± 18.70 kJ kg(-1) of shrunk BW(0.75); SBW(0.75)), partial efficiency of ME utilization for maintenance (k m; 0.64 ± 0.02 vs. 0.65 ± 0.03), partial efficiency of ME utilization for growth (k g ; 0.42 ± 0.03 vs. 0.44 ± 0.02), and net protein (NP) requirement for maintenance (NPm; 1.83 ± 0.17 vs. 1.99 ± 0.28 g kg(-1) of SBW(0.75)) did not differ (P > 0.05) due to gender; although not statistically different, the mean value of Net energy (NE) requirement for maintenance (NEm) for male lambs (260.62 ± 13.21 kJ kg(-1) of SBW(0.75)) were 5 % greater than that (274.16 ± 11.99 kJ kg(-1) of SBW(0.75)) of female lambs. Additionally, rams have greater amounts of NP requirement for growth (NPg, 15.94 to 44.32 g d(-1)) than those of ewes (13.07 to 32.95 g d(-1)) at the similar condition of BW and ADG. In conclusion, we suggested that our results of energy and protein requirement for growth ranged between the NRC recommendation for early and later maturating growing sheep, and the effect of gender upon energy requirement parameters was similar in tendency but was less evidently than those frequently recommended previously.

Production of myostatin-targeted goat by nuclear transfer from cultured adult somatic cells.

Myostatin, a member of the transforming growth factor-ß family, acts as a negative regulator of skeletal muscle mass. In this study, myostatin-targeted caprine fibroblasts were obtained and subjected to SCNT to determine whether myostatin-knockout goats could be created. Fibroblasts from a 2-mo-old goat were transfected with a myostatin-targeted vector to prepare transgenic donor cells for nuclear transfer. After serum-starvation (for synchronization of the cell cycle), the percentage of transgenic fibroblasts in the G(0)/G(1) phase increased (66.2% vs. 82.9%; P < 0.05) compared with that in the control group, whereas the apoptosis rate and mitochondrial membrane potential were unaffected (P > 0.05). There were no significant differences between in vivo- and in vitro-matured oocytes as recipient cytoplasts for rates of fusion (86.5% vs. 78.4%), pregnancy (21.6% vs. 16.7%), or kidding (2.7% vs. 0%). One female kid from an in vivo-matured oocyte was born, but died a few hours later. Microsatellite analysis and polymerase chain reaction identification confirmed that this kid was genetically identical to the donor cells. Based on Western blot analysis, myostatin of the cloned kid was not expressed compared with that of nontransgenic kids. In conclusion, SCNT using myostatin-targeted 2-mo-old goat fibroblasts as donors has potential as a method for producing myostatin-targeted goats.

Efficiency of donor cell preparation and recipient oocyte source for production of transgenic cloned dairy goats harboring human lactoferrin.

The objective was to investigate the effects of the transgenic donor cell synchronization method, oocyte sources, and other factors, on production of hLF-gene nucleus transfer dairy goats. Three transfected cell lines from ear biopsies from three 3-mo-old Saanen dairy goats (designated Number 1, Number 2, and Number 3, respectively) were selected as karyoplast donors for somatic cell nuclear transfer (SCNT) after detailed identification (including PCR and sequencing of PCR products). In donor cell cycle synchronization studies, the apoptosis rate of hLF transgenic fibroblasts was not different (P > 0.05) after 3 days of serum starvation or 2 days of contact inhibition. Additionally, there was no effect (P > 0.05) on developmental capacity of reconstructed embryos; however, the kidding rate of recipients in the serum starvation group was higher than that in the contact inhibition group (18 vs. 0%, respectively). The production efficiency of the transgenic cloned goats using donor cells from the Number 1 dairy goat cell line was higher than those using the Number 2 and the Number 3 cell lines (kidding rates were 18, 2, and 0%, respectively, P < 0.05). The oocyte source did not significantly affect the pregnancy rate of hLF-transgenic cloned dairy goats, but more fetuses were aborted when using in vitro matured oocytes compared to in vivo matured oocytes. In summary, utilizing transfected 3-mo-old dairy goat fibroblasts as donor cells, seven live offspring were produced, and the hLF gene was successfully integrated. This study provided additional insights into preparation of donor cells and recipient oocytes for producing transgenic cloned goats through SCNT.