This study was conducted at the National Institute of Animal Science (NIAS) from 2010 to 2017 to develop a late-maturing variety with high productivity for cultivation in the southern region of South Korea. The new variety of Italian ryegrass, ‘IR901’, was a late-maturing variety, and its heading date was 22 May, 17 days later than that of the control variety ‘Kowinearly’. ‘IR901’ had a flag leaf width of 11.2 mm, flag leaf length of 31.8 cm, and plant length of 103 cm on its heading date. The combined average dry matter yield of ‘IR901’ in all three adaptability evaluation regions (Cheonan, Pyeongchang and Haenam) was 7,747 kg/ha, which was similar to that of the ‘Kowinearly’ variety (7,734 kg/ ha). However, the average dry matter yield over three years in Cheonan and Pyeongchang was 82% and 96%, respectively, compared to that of the control, which was most likely because of the poor cold tolerance of ‘IR901’. By contrast, in Haenam, in the southern region, the average dry matter yield of ‘IR901’ was 19% higher than that of the ‘Kowinearly’ variety. The proportions of crude protein (CP), total digestible nutrients (TDN), acid detergent fiber (ADF), and neutral detergent fiber (NDF) in ‘IR901’ were 8.6%, 59.7%, 36.9%, and 54.8%, respectively; the proportions were 0.2% lower, the same, the same, and 2.5% lower than those in the ‘Kowinearly’ variety. The determined in vitro dry matter digestibility (IVDMD) of ‘IR901’ was 72.2% higher than that of ‘Kowinearly’ (67.2). In general, of the two varieties, the forage quality of ‘IR901’ was marginally superior to that of ‘Kowinearly’.

This study was conducted at the National Institute of Animal Science from 2010 to 2017. As a variety that is sufficiently productive in the southern regions to replace imported varieties and sufficiently cold-resistant to be cultivated in the central-northern regions, "IR605" was developed and submitted to the Korea Seed & Variety Service in an application for protection. The novel Italian ryegrass variety "IR605" is a diploid with green leaves, a semi-erect growth habit before wintering, and an erect growth habit in the spring. "IR605" was a medium maturing variety with a heading date of around May 15th. "IR605" had a flag leaf width of 9.9 mm, flag leaf length of 26.7 cm, and plant length on the heading date of 100 cm, which was approximately 5 cm longer than "Kowinearly." The stem thickness and ear length of "IR605" are 0.08 mm thicker and 0.5 cm longer than those of "Kowinearly", respectively. The cold-resistance of "IR605" was weaker than that of "Kowinearly", but strong enough to be cultivated in Pyeongchang, Gangwon province. The dry matter yield of "IR605" (9,308 kg/hectare) was 20% higher than that of "Kowinearly", which was further pronounced in the southern region of Haenam, where there was a 52% increased (p < 0.05). The in vitro dry matter digestibility of "IR605" was 68.4% at which was slightly higher than that of "Kowinearly", The total digestible nutrients was 58.5%, which was slightly lower than "Kowinearly". Overall, the feed quality characteristics of "IR605" were similar to those of "Kowinearly".

The present study was conducted to investigate the effect of BHT supplementation on sperm motility, viability, acrosomal integrity and plasma membrane integrity after frozen-thawing. One ejaculate was collected from one fertile Hanwoo bull by using artificial vagina at Hanwoo Research Institute. The ejaculate was transferred to laboratory immediately and diluted with pre-warmed semen extender (Optixcell, France) (1:1). Sperm dilutions were extended to a final concentration of 40 x 106 sperm/ml, and divided into 5 groups according to BHT concentration (0, 0.5, 1.0, 2.0 and 4.0 mM) and cryopreserved in LN2 tank until evaluation. Frozen-thawed semen was transferred to 1.5 ml tube and incubated for 0, 2 and 4h. Sperm motility and motility parameters (total motility, VSL with 25μm≥, VCL, VSL, VAP, LIN, STR, WOB, ALH and BCF) were evaluated by sperm class analysis (SCA, IVOS, Spain). There were not significant effects of BHT supplementation (0, 0.5, 1.0 and 2.0 mM) on total motile and VSL with 25μm≥ at 0, 2 and 4h. However, 4.0 mM of BHT supplementation showed negative effect on total motile (26.3%), VSL with 25μm≥ (1.3%) at 0 h (p<0.001). The viability and acrosomal integrity of spermatozoa were evaluated by Trypanblue/Giemsa staining method and divided into 4 groups; live and intact acrosome (LIA), live and damaged acrosome (LDA), dead intact acrosome integrity (DIA), dead damaged acrosome (DDA). There were no significant differences of LIA, LDA, DIA and DDA on various BHT concentrations at 0 and 2 h. However, 4.0 mM BHT supplementation showed decreased LIA compared with 0, 0.5, 1.0 and 2.0 mM BHT at 4 h (34.6, 37.1, 43.6, 45.4 and 14.7% vs. 0, 0.5, 1.0, 2.0 and 4.0 mM, irrespectively; p<0.01). Addition of 4.0 mM of BHT showed negative effect on plasma membrane integrity compared with that of 0, 0.5, 1.0 and 2.0 BHT at 2 h (71.9, 64.2, 64.6, 67.5 and 31.7 % vs. 0, 0.5, 1.0, 2.0 and 4.0 mM, irrespectively; p<0.05). In conclusion, various BHT concentrations on optixcell extender showed no improvement on sperm motility, viability and plasma membrane integrity.

This experiment was carried out to investigate the effect of harvesting time of Italian ryegrass (Lolium multiflorum Lam; IRG) in spring on dry matter (DM) yield. IRG cultivars ‘Kowinearly’ and ‘Greenfarm’ were seeded at 50 kg/ha and grown on rice paddy fields. There was no difference in growth characteristics between both varieties before winter. However, cold tolerance of Kowinearly was higher than that of Greenfarm, as demonstrated by post-wintering growth characteristics. The heading date of both varieties was affected by the spring weather. The IRG was harvested three times at 5-day intervals beginning from 9 May. The DM yield of Greenfarm was 6,306; 7,335; and 8,109 kg/ha, and that of Kowinearly was 7,498; 9,196; and 10,449 kg/ha at the three consecutive harvests. The delay of the harvesting time for 5 and 10 days increased the DM yield of Greenfarm by 16% and 29% and that of Kowinearly by 23% and 39%, respectively, compared to the yield at first harvest (p < 0.05). Therefore, IRG harvest later than early to mid-May is expected to increase productivity. The feed values of Greenfarm were: 12.2% of crude protein (CP), 34.5% of acid detergent fiber (ADF), 57.7% of neutral detergent fiber (NDF), 61.6% of total digestible nutrients (TDN), and 72.3% of in vitro DM digestibility (IVDMD). For Kowinearly, these values were 16.4% of CP, 30.4% of ADF, 52.7% of NDF, 64.9% of TDN and 79.0% of IVDMD.

The present study investigated the effects of different seeding rates on growth characteristics and seed productivity of the “Kowinearly” cultivar of Italian ryegrass (Lolium multiflorum Lam.) in paddy fields. Sowing Kowinearly in paddy fields under growing rice at the rates of 20, 30, 40, and 50 kg/ha resulted in seed yields of 1.57, 1.92, 2.06, and 2.09 ton/ha, respectively. Seed yield of Kowinearly was the highest at a seeding rate of 50 kg/ha (p<0.05), at which the cultivar was able to survive in winter and the weed ratio was low. Under these conditions, most growth characteristics such as winter survival (85%), weed ratio (10%), stems per square meter (1,006) were superior than those sown at other seeding rates (p<0.05). In addition, it has been reported that the economic efficiency of the 50 kg/ha seeding rate was higher than that of the other seeding rates.

Sperm recovery from epididymis in animals considered as important tools to preserve high-value or endangered species. However, there are no appropriate castrating indicators of timing for recovery of sperm which can be available to artificial reproduction technologies such as artificial insemination (AI) and in vitro fertilization (IVF), particularly in young Hanwoo bull. Therefore, this study aimed to investigate semen volume, morphology and motility of sperm in epididymis of young Hanwoo bulls at 8, 13, 14, and 15 months of age. About 2 cm of the epididymal tail only was cut and minced using blades. Minced epididymal tail tissues were mixed with semen extender (OptixCell, France, IMV technologies) and sperm were recovered with a cell strainer (100 μm nylon mesh). The number of sperm at 8 months of age was lower than that at 13, 14, 15 months of age in bulls after collection (33.6±27.2 vs. 352.4±39.2, 320.4±113.6 and 422.8±252.4×107cells respectively; P<0.05). After the frozen-thawed sperm the the percentage of abnormal head, tail and dead damaged acrosome did not differ between the ages 13, 14 and 15 months of age in bulls (P>0.05), however, the dead sperm with intact acrosome (DIA), the numbers showed that more than 15 months in 8, 13, 14 months (8.7±4.1 vs. 47.3±12.2, 34.8±14.0, 28.8±8.5, P<0.05). In addition, frozen-thawed sperm at 8 months of age showed low total motile sperm compared to those at 13, 14 and 15 months of age (26.4±8.2 vs. 45.7±29.5, 62.3±41.0, 70.4±15.9%, respectively; P<0.05). In conclusion, sperm derived from epididymal tail at 8 months of age in Hanwoo bulls showed high abnormal morphology and poor motility, which is not adequate for artificial insemination(AI) and in vitro fertilization(IVF). On the other hand, sperm derived from epididymal tail at 13, 14, 15 months of age in bull showed high normal morphology and motility, which may be available for AI and IVF. Epididymal sperm collected from bulls over 13 months is needed for further study whether to use the actual in vitro fertilization.

Semen collection from epididymis has been used as an important alternative tool, particularly on abnormal animals including those with joint disorder, poor sex drive and poor libido. However, previous studies had been focused on only recovery of sperm derived from testes, regardless of fundamental parameters such as age, body weight, scrotal circumference, testicular size (weight, length, width and volume) and semen volume. In addition, there is no precise castrating periods to recover sperm from young Hanwoo bulls’ testis. Therefore, we investigated fundamental parameters in Hanwoo bulls at 7, 8, 14, 15, 16 and 17 months of age, which parameter can be used for sperm recovery from testis. Before castration, body weight and scrotal circumference were recorded. After castration, testes were transported to laboratory and testicular weight, length and width were recorded. About 2 cm of epididymal tail was collected and minced using blades on 100 mm petridish. Minced epididymal tail tissues were mixed with Optixcell (France, IMV technologies) and debris were removed by filteration with 100 um nylon mesh. Seven to 8 months of age in bulls showed low fundamental parameters compared to those of at 14 to 17 months of age in bulls (body weight, 218-258 vs. 330-429 kg; scrotal circumference, 23.4-24.6 vs. 28.8-32.8 cm; testicular weight, 92-104 vs. 222.3-269.9 g; testicular length, 10.9-11.6 vs. 13.4-15.6 cm; testicular width, 4.7 vs. 6.2-6.6; testicular volume, 126.4-136.4 vs. 268.9-357.6 cm3, semen volume, 3.0-4.8 vs. 60.6-68.3 ml, p<0.001). In conclusion, to recover semen derived from epididymis of testis in young Hanwoo bull, these fundamental parameters should be satisfied; 330 kg of body weight, 28.8 cm of scrotal circumference, 222.3 g of testicular weight, 13.4 cm of testicular length, 6.2 cm of testicular width, 268.9 cm3 of testicular volume. In further study, fundamental parameters of 9 to 13 months of age in bull should be investigated to determine more accurate castrating periods for sperm recovery from testis.