• Asian-Australasian Journal of Animal Sciences
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• v.25 no.1
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• pp.22-27
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• 2012

The experiment involved observations of 2,514 Holstein-Friesian cows to determine the effects of environmental factors (cow's age, calving season, weight and sex of calves, housing system) and genetic factors on gestation length in dairy cattle and the correlation between gestation length and other reproductive traits (calving ease, stillbirth rates and placental expulsion). Genetic parameters were estimated based on the sires of calved cows (indirect effect) and the sires of live-born calves (direct effect). The following factors were found to contribute to prolonged gestation: increasing cow's age, male fetuses and growing fetus weight. Optimal gestation length was determined in the range of 275-277 days based on calving ease and stillbirth rates. The heritability of gestation length was estimated at 0.201-0.210 by the direct effect and 0.055-0.073 by the indirect effect. The resulting genetic correlations suggest that the efforts to optimize (prolong) gestation length could exert an adverse influence on the breeding value of bulls by increasing perinatal mortality and calving difficulty. The standard errors of the investigated parameters were relatively high, suggesting that any attempts to modify gestation length for the purpose of improving calving ease and reducing stillbirth rates should be introduced with great caution.

• Journal of Animal Environmental Science
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• v.19 no.2
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• pp.117-122
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• 2013

The study was conducted to develop an ESF (electronic sow feeder) for improving animal welfare of group housed gestation sows. Feed intake of both individual and group housed gestation sows was restricted 2 kg a day. ESF system was very effective in reducing feed loss. The amount of feed loss in treatment group (group housed gestation sows with ESF) was only about 55 g, while the amount of feed loss in control group (individually housed gestation sows) was about 200 g. In spend time to feed intake, there was no difference in the result between the control (about 30 min) and the treatment (about 22 min) group. The ESF system ran well without any mechanical problems throughout the entire experiment. These results suggest that the EST is expected to improve the performance feeding of sows.

• Korean Journal of Veterinary Research
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• v.43 no.3
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• pp.349-359
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• 2003

Corpus luteum (CL) is the primary productive organ of progesterone in pregnant cows. Progesterone levels in bovine plasma depend on the volume, weight and shape of the CL. Progesterone productions during the late stages of gestation occur both in the CL and placenta, and placentas producted more progesterone than CL on progesterone prcduction. Because division of progesterone production of these two organs is impoxxible, the CL function can not be determined by plasma progesterone levels following gestation stages. This study was carried out to evaluate histological findings on the CL spurium and CL verum, and also on the CL following the pregnant stages by histological and immunohistochemical and electron microscopical methods and then we expect to assume the functions of CL by histological findings. 1. Proliferations of luteal cells occur by day 120 of gestation, vessel hyperplasia occur by day 90 of gestation, and the walls and lumens of vessels developed by day 120 of pregnancy. 2. Sizes of CL cells increased to maximum around day 200 of gestation and similarly maintained by day 240. So these findings indicated that the function of Cl is most active around day 200 of gestation. 3. On parturation day, the number and size of luteal cells were maintained but stain intensity of the luteal cells and vessels are declined or disappeared, and fibrosis of luteal cells increased, and the vessel lumens are emptied. These findings indicate that CL is inactive. 4. In immunohistochemical findings, proliferative positive cells by PCNA antibody appeared more in number during early stages of gestation but appeared less following course of pregnant stages and not nearly appeared on day 120 of gestation. Apoptotic positive cells by TUNEL methods not nearly appeared on the early pregnant stages and a few appeared at late pregnant stages. So developments of CL proceed until day 120 of gestation and regression of CL was occurred by transform of luteal cells into fibrocytes than by luteal cell apoptosis. 5. In electron microscopical findings, the size of luteal cells increased more in CL verum than in CL spurium. During gestation stages, the size of luteal cells increased, mitochondria in the luteal cell cytoplasms densely and abundantly developed and also swelled mitochondria increased. The interspace of luteal cells are also dilated, transformation of luteal cells into fibrocytes are more number. The lumens and walls of peripheral capillaries of large luteal cells more broadened and thickened, and transformation of large and small luteal cells to fibrocytes are increased. The above findings suggest that function of pregnant CL more developed by day 120 of gestation and are most active around day 200 of gestation and similarly maintained by day 240 and are promptly regressed on paturation day.

• Korean Journal of Veterinary Research
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• v.22 no.1
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• pp.75-79
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• 1982

Serum glutamic oxaloacetic transaminase (GOT), latic dehydrgenase (LDH), and alkaline phosphatase (ALP) activities were determined in 5 Korean native cattle to obtain the base line of blood enzyme activities in relation to the stage of gestation. Serum GOT activities showed an increasing tendency with the course of gestation period, serum LDH levels were within normal range through all the stage of pregnancy, and the slight increase in serum ALP activities was acknowledged at the 2nd and 3rd stage of gestation.

• Korean Journal of Veterinary Service
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• v.20 no.1
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• pp.55-67
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• 1997

The morphological development of lungs in fetuses of 60, 90 and 120 days of gestation and neonates of Korean native goats was investigated by light, scanning and transmission electron mictroscope. The results were summarized as follows ; 1. Gross findings ; In the 60-days-old fetus, the lung was developed and differentiated into six lobes. 2. Light microscopic findings : The gland-like bronchioles were formed in loose mesenchyme at 60 days of gestation and the bronchial wall contained smooth muscles. The loose mesenchyme had been replaced by compact parenchymal tissue at 90 days of gestation and the cartilage plates appeared in bronchial wall which contained blood vessels, submucosal glands and smooth muscles. The lung parenchyma consisted of a fine network of alveoli at 120 days of gestation and the bronchial wall contained well-developed blood vessels, submucosal glands, cartilage plates and smooth muscles. In neonates, the lung tissue was similar to the mature lung tissue and the bronchial wall contained well developed cartilage plates. 3. Scanning electron microscopic findings : The epithelial cells lining the tubules were composed of cuboidal or columnar at 60 days of gestation and the epithelial cells lining the large airways were often ciliated : some were covered with stubby microvilli. The epithelial cells lining the canals were cuboidal at 90 days of gestation and the epithelial cells lining the bronchioles were ciliated cells or nonciliated(clara) cells, The clara cells contained row microvilli. The alvealor development of this stage was rapidly progressed ; the subdivision of canals by alveolar crests and assosiated wall attenuation resulted alveoli at 120 days of gestation and the respiratory bronchioles were lined by ciliated or nonciliated epithelial cells. In neonates, the epithelial cells lining the alveolar walls were mainly covered with pneumocyte type I ; Some were covered with pneu-mocyte type II. 4. Transmission electron microscopic findings : The epithelial cells lining the tubules were adhered with tight junction at apical borders of the adjacent cells at 60 days of gestation, which contained few organells and glycogen. The epithelial cells lining the canals were composed mostly of cuboidal cell at 90 days of gestation and the epithelial cells lining of the bronchioles were ciliated of nonciliated cell, which contained few organelles and abundant glycogen. The epithelial cells lining the alveolar walls were composed of pneumocyte type I and a few pneumocyte type II at 120 days of gestation. The epithelial cells lining of the bronchioles were ciliated or nonciliated cells. In neonates, pneumocyte type I was observed as flat and thin cytoplasmic extension in shape. Otherwise, pneumocyte type II was observed as cuboidal type with apical microvilli and contained osmiophillic lamellar inclusion bodies. Putting these various experiment results together, the lung development was slowly progressed at early stage, which was rapidly progressed in the late stage of gestation.

• Korean Journal of Agricultural Science
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• v.48 no.2
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• pp.265-272
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• 2021

A total of fourteen primiparous sows' (Landrace × Yorkshire) were used to determine the effects of two patterns of feed intake during early gestation on the growth performance and litter characteristics in sows. Daily feed intake from day 5 to 112 of gestation for parity 1 sows was 2.2 kg·d^-1 of feed offered with the exception of seven sows who were offered 3.2 kg·d^-1 from day 90 to 108 of gestation (TRT A) or 2.5 kg·d^-1 (d 5 - 60) and 2 kg·d^-1 (d 60 - 90) of feed with the exception of seven sows who were offered 3.5 kg·d^-1 from day 90 to 108 of gestation (TRT B). The different feed intake patterns in early gestation did not have a significant effect on body weight, backfat thickness, or body condition score during, before, and after farrowing (p > 0.05) respectively. However, initial to d 60, backfat thickness difference was significantly improved by TRT B patterns of feed intake during early gestation. In addition, during the overall experiment, average daily feed intake was significantly enhanced for sows in the dietary TRT B group feed intake pattern (p = 0.0001). The fecal score during day 90 was significantly reduced (p = 0.0132) in sows fed with TRT B feed intake pattern. Litter size, litter survival rate, and initial weight showed no significant differences with different feed efficiency of gestating sows. In summary, the results indicate that the 2.5 kg·d^-1 gestation intake pattern allowed gestating sows to obtain optimal performance.

• Animal Bioscience
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• v.36 no.12
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• pp.1880-1888
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• 2023

Objective: The present experiment aimed to determine standardized ileal digestible (SID) lysine (Lys) requirements for pregnant sows individually housed under commercial farm conditions. Methods: Two hundred multiparous sows (parity = 5.1±2.0) on day 42 of gestation were randomly allocated to five dietary treatments with a balanced parity. Experimental diets were formulated to contain 0.22%, 0.32%, 0.42%, 0.52%, and 0.62% of SID Lys for the mid-gestation period (days 42 to 76) and 0.36%, 0.46%, 0.56%, 0.66%, and 0.76% of SID Lys for the late gestation period (days 77 to 103). All indispensable amino acids except Lys were provided at 110% of their requirement estimates. Daily feed allowance per sow was determined based on the back-fat thickness and body condition score at the second pregnancy check and on day 90 of gestation. Three different statistical models were used to estimate the SID Lys requirement. Results: Total born piglets alive per litter increased linearly and quadratically (p<0.001) as dietary SID Lys increased. For total born piglets alive per litter, the SID Lys requirement estimates ranged from 9.69 to 12.4 g/d for the mid-gestation period (1.19 to 1.52 g/Mcal metabolizable energy; 0.39% to 0.49%) and 14.6 to 17.4 g/d for the late gestation period (1.62 to 1.93 g/Mcal metabolizable energy; 0.52% to 0.62%). Conclusion: The mean values of the SID Lys requirement for the mid-gestation period and the late gestation period are 11.1 and 16.1 g/d (1.36 and 1.79 g/Mcal metabolizable energy; 0.44% and 0.58%), respectively, for maximal total born piglets alive per litter.

• Applied Microscopy
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• v.28 no.3
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• pp.283-297
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• 1998

Hemopoiesis and morphogenesis of the human fetal liver through from 10 to 32 weeks of gestation were investigated by light and electron microscopy. The results obtained were as follows. Hemopoiesis of fetal liver tissue was found from 10 to 32 weeks of gestation, but the hemopoiesis was decreased at 32 weeks of gestation. At the 32 weeks of gestation, matured erythrocytes were observed in the sinusoid, and formation of liver cell cord and portal triad were established. Differentiation of hepatic cell was characterized by the increase of amount of cell organelles within cytoplasm, decrease of hemopoietic cell, morphological change of nuclear envelope from folding form to round form during the developmental period. These results suggest that human fetal liver plays a hematopoietic function until bone marrow and spleen play their function, but morphology of liver at 32 weeks of gestation was differed with structure observed in liver of adult.

• Journal of Veterinary Clinics
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• v.16 no.2
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• pp.389-396
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• 1999

Pregnant rats were treated at various stages of gestation with prostaglandin analogue, cloprostenol alone or concomitant with HCG to study effects on termination of gestation and plasma estrogen and progesterone. Cloprostenol (90 or 180 mg/kg) was administered alone on 1~3, 4~6, 7~9, 9~11 or 11~13 consecutive days of gestation twice a day and in combination with HCG (50 or 100 IU/day) on days of 1~3 or 7~9 once a day. Rats were autopsied on day 21 of gestation or at 6, 12 or 24 hours after treatment on day 6 or 9, respectively. Cloprostenol was found to be nearly 100% effective in preventing implantation, destroying viable fetuses and causing preimplantation losses, but in early gestation, on days 1-3, there was little effect. And when cloprostenol administered concomitant with HCG, corpora lutea were significantly increased, implantation sites and viable fetuses significantly decreased, and pre-and post-implantation losses significantly increased in most cases. Plasma concentrations of estradiol and progesterone were significantly decreased by administering cloprostenol, and estradiol concentration significantly decreased but progesterone significantly increased by administering of cloprostenol concomitant with HCG. It is suggested that cloprostenol was more effective in terminating pregnancy than a combination of cloprostenol and HCG in the rat.

• Toxicological Research
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• v.32 no.4
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• pp.275-280
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• 2016

Prenatal nicotine exposure over an entire pregnancy has been associated with an increased prevalence of hyperactivity, anxiety-like behavior and depression-like behavior in mature rats. However, the effects of maternal nicotine exposure in late gestation and lactation on the psychology and behavior of adolescent rat offspring are unclear. Thus, we investigated the effect of nicotine exposure during late gestation and lactation on anxiety-like and impulsive decision-making behavior in adolescent offspring of rat. Female rats were orally exposed to nicotine which is within range of plasma level of human chronic smokers during the period of third last period of gestation and lactation. When the offspring were weaned, we observed alterations in the anxiety-like behavior and decision-making ability of adolescent rat offspring using light/dark box test and T-maze delay-based cost-benefit decision-making task. The maternal consumption of nicotine reduced both the time spent in the light compartment and the number of transitions compared to nicotine-free rats. Moreover, such nicotine exposed adolescent offspring rats showed impulsive decision making which chose the instant reward in a decision-making situation. We found that nicotine exposure during late gestation and lactation induces an increase in anxiety-like and impulsive decision-making behavior at this developmental stage. These findings suggest that maternal nicotine-exposed offspring are at an increased risk of developing anxious and impulsive behavior.