• Journal of Embryo Transfer
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• v.29 no.1
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• pp.7-12
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• 2014

This work was conducted to study the improvement of reproduction rate from the breeding data collected from four farms from January 2007 to October 2010. The average numbers of service per conception were 1) A farm $1.7{\pm}0.1$ times, 2) B farm $1.5{\pm}0.1$ times, 3) C farm $1.5{\pm}0.1$ times, 4) D farm $1.4{\pm}0.1$ times. The average days from calving to conception was $77.4{\pm}4.8$ days in A farm, $150.8{\pm}11.2$ days in B farm, $90.4{\pm}4.5$ days in C farm, and $71.4{\pm}2.5$ days in D farm. Number of artificial insemination (AI) service per conception was higher at the 30 days before first AI ($2.1{\pm}0.2$ times) than at the 31 days after first AI, and the days from calving to conception were shorter at the 90 days before first AI than at the 91 days after first AI. After timed AI (TAI) treatment, the pregnancy rate was 60.3% for the 58 cows with reproductive disorder. In order to improvement of reproduction rates, the farms has to improve the accuracy of estrus detection, pregnancy diagnosis, check-up for reproductive health, and control of day for first AI periods after calving. The result suggests that farmers need the careful management and reproductive examination of farm animals to improve of reproductive efficiency.

• Journal of Veterinary Clinics
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• v.27 no.4
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• pp.397-401
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• 2010

This study was to evaluate the usefulness of a programmed reproductive management including Presynch-Ovsynch-Resynch protocol in lactating dairy cows. Nine hundred and thirty four cows calved during February to May 2008 were used for this study. Cows received im injections of 25 mg $PGF_{2{\alpha}}$ at $45{\pm}3$ and $59{\pm}3$ days in milk (DIM). Fourteen days later, Ovsynch was initiated with an im injection of $100\;{\mu}g$ GnRH ($73{\pm}3$ DIM), 25 mg $PGF_{2{\alpha}}$ 7 days later ($80{\pm}3$ DIM), $100\;{\mu}g$ GnRH 56 h later and timed artificial insemination (TAI) 16 h after the GnRH injection. Cows showed estrus during the Presynch-Ovsynch, were inseminated artificially according to am-pm rule. Pregnancy was determined on 32 days after AI using ultrasonography. Cows diagnosed pregnant were re-examined for pregnancy by rectal palpation at 60 days after AI. Non-pregnant cows were resynchronized by receiving $100\;{\mu}g$ GnRH, 25 mg $PGF_{2{\alpha}}$ 7 days later, $100\;{\mu}g$ GnRH 56 h later and TAI 16 h after. Cows with estrus since the first AI before the completion of Resynch protocol were also inseminated artificially according to am-pm rule. Pregnancy was determined by the same manner as following the first AI. Fifty five percents of the cows treated showed estrus and received AI before completion of the Presynch-Ovsynch protocol, while 45% received TAI, regardless of estrus exhibition following the completion of the protocol. The pregnancy rate following the first AI was higher in cows that showed estrus and received AI (43.3 and 38.5%) during the Presynch-Ovsynch than cows with TAI (34.6 and 29.6%) on 32 and 60 days after AI (P < 0.01). Sixty six percents of cows diagnosed non-pregnant following the first AI showed estrus before the completion of Resynch protocol and received AI, while 34% received TAI, regardless of estrus exhibition following the completion of the protocol. The pregnancy rate following the second AI was higher in cows that showed estrus before the completion of Resynch protocol and received AI (40.2 and 36.8%) than cows with TAI (21.2 and 18.2%) on 32 and 60 days after AI (P < 0.01). The cumulative pregnancy rates following the first and second AIs were 60.8 and 53.9% on 32 and 60 days after AI, respectively. These data suggest that inclusion of Presynch-Ovsynch-Resynch protocol and estrus detection into the programmed reproductive management might be an alternative option to control dairy cattle breeding.

• Journal of Embryo Transfer
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• v.27 no.4
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• pp.223-228
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• 2012

This study was designed to adopt two estrus synchronization protocols in zebu and crossbred heifers and their effects on pregnancy rate after timed artificial insemination (TAI). A number of 120 cyclic heifers were allotted for two different treatment groups and one control group. Heifers under protocol A were injected with GnRH at first day followed by a single dose of $PGF_{2{\alpha}}$ at Day 11 and injection of GnRH at the day of AI; and heifers belonged to protocol B were treated with GnRH, two $PGF_{2{\alpha}}$ injections at 11 days apart and injection of GnRH at AI. AI was done at fixed time (within 72~96 hours after $PGF_{2{\alpha}}$ injection) in both protocols and pregnancy was confirmed by rectal palpation on 80~120 days of post AI. In control group; local heifers were conceived higher (30%) proportion than that of crossbred heifers (25%; p<0.05). In protocol A, the local breed were conceived higher (38.9%) proportion compared with crossbred (25%; p<0.05). In protocol B, local breed heifers were conceived higher (38.9%) proportion compared with crossbred heifers (33.3%; p<0.05). The overall pregnancy rate in protocol A and protocol B was 33.3% and 36.6%, respectively. The proportion of pregnancy rate of local heifers (38.9%; Protocol A) was significant (p<0.05) in comparison with local heifers (30%) in control group (p<0.05). The overall pregnancy rate between pooled control group (28.3%) and treatment group (35%) was significantly (p<0.05) differ from each other's. Results of present study concluded that estrus synchronization followed by fixed time AI could be applied for higher pregnancy rate in zebu and crossbred heifers.

• Journal of The Korean Society of Grassland and Forage Science
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• v.38 no.4
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• pp.331-336
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• 2018

The aim of the present study was to identify the metabolic changes that have occurred in Hanwoo Native Cow. Analysis of serum metabolites was carried out to investigate relationship of pregnancy rate and feeding systems. Totally, 281 cows were used for grazing and barn feeding. Grazing was carried out for 5 months in the pasture. In barn feeding, concentrate 3.0 Kg(TDN 68%, CP 14%) and rice straw 6 kg(TDN 50%, CP 6.5%) were fed. Artificial insemination(AI) carried out by timed AI procedure. The level of glucose(mg/dl), cholesterol(mg/mL), BUN(mg/dl), AST(U/l), ALT(U/l), and NEFA(uEq/l) were analyzed. In Table 1, barn feeding with 120% group was showed high Cholesterol and BUN levels compared those with 80% feeding group(p<0.05). In Table 2, 60 pregnant cows in grazing herd showed low Cholesterol, AST and NEFA levels compared to 43 non-pregnant cows($149.8{\pm}4.9$, $99.1{\pm}2.6$, $326.7{\pm}15.7$ vs. $165.9{\pm}4.6$, $108.9{\pm}3.2$, $419.2{\pm}32.8$, respectively, p<0.05). In Table 3, 126 grazing feeding cows showed high Glucose, Cholesterol, AST, ALT, and NEFA levels compared to 22 barn feeding cows($84.8{\pm}1.3$, $142.5{\pm}2.5$, $97.7{\pm}2.3$, $34.3{\pm}0.5$, $317.8{\pm}13.6$ vs. $56.0{\pm}1.3$, $128.9{\pm}4.6$, $80.9{\pm}2.0$, $27.1{\pm}0.9$, $160.2{\pm}18.9$, respectively, p<0.05). Further study needed to obtain more accurate level of metabolites in serum for pregnant and non-pregnant cows.