• Korean Journal of Veterinary Research
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• v.59 no.4
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• pp.181-185
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• 2019

The traditional calculation of gestation length (GL) in Holstein cows relies solely on the insemination day and has a high error rate for actual calving dates. The present study was conducted to develop a more accurate method of estimating GL. Among 3,578 Holstein cows, the number of fetuses had a significant (p < 0.05) effect, with GLs of 282.4 ± 2.5 days for singletons and 276.0 ± 1.6 days for twins. Within the singleton group, the GLs were 284.6 ± 1.9 days for males and 280.3 ± 1.5 days for females, a significant difference (p < 0.05). However, within the twin group, there was no difference in GLs among twin males, twin females, or twins of both sexes. Gestation was significantly shorter for singleton males born from June to August but significantly longer for twin males born in the May to June period (p < 0.05). Neither parity nor housing type was associated with any significant difference in GL. In order to predict the calving dates of Holstein cows accurately and improve their management, calculations should consider the number and sex of fetuses as well as the insemination season.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.9
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• pp.1328-1333
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• 2009

To evaluate different housing systems, 80 gilts were randomly allocated at puberty to four treatments: i) sow stall in gestation followed by farrowing crate (SC), ii) group housing with individual feeding in gestation followed by farrowing crate (GC), iii) ESF (Electronic Sow Feeding) system in gestation followed by farrowing crate (EC), and iv) ESF system followed by group farrowing pen (EG). The results showed that stalled sows had a longer interval between puberty and second estrus (p<0.001). The sows kept in the ESF system gained more body weight (p<0.01) and backfat (p<0.05) prior to service, and more backfat during gestation (p<0.05), but also had greater backfat losses in the subsequent lactation (p<0.01). Sows changing from loose housing to confinement at farrowing had longer gestation length (p<0.001). Total litter size did not differ significantly between gestation treatments, but the number of stillborn piglets was significantly higher in the SC treatment (p<0.01). After weaning, SC sows had the longest interval for rebreeding (p<0.001). Some EG sows came into heat before weaning, giving this treatment the shortest interval. These results indicate that gestation confinement in sow stalls had several detrimental effects on sow performance relative to group housing.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.5
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• pp.633-639
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• 2008

The genetic relationship of gestation length (GL) with birth and weaning weight (BW, WW) was investigated using data collected from the Hanwoo Experiment Station, National Institute of Animal Science, RDA, Republic of Korea. Analytical mixed models including birth year‐season, sex of calf, linear and quadratic covariates of age of dam (days) and linear covariate of age at weaning (days) as fixed effects were used. Corresponding restricted maximum likelihood (REML) and Bayesian estimates of variance components and heritability were obtained with two models; Model 1 included only direct genetic effect and Model 2 included direct genetic, maternal genetic and permanent environmental effect. All the genetic parameter estimates from REML were corresponding to the Bayesian estimates. Direct heritability estimates for GL, BW, and WW were 0.48, 0.33 and 0.25 by Model 1. From Model 2, direct and maternal heritability estimates were 0.38 and 0.03 for GL, 0.14 and 0.05 for BW, and 0.08 and 0.05 for WW. Genetic correlation estimates between direct and maternal effects were 0.05 for GL, 0.59 for BW, and 0.52 for WW. Estimates of direct genetic correlation between GL and BW (WW) were 0.44 (0.21). Positive genetic correlation of GL with BW and WW imply that selection for greater BW or WW would lead to prolonged gestation length.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.7
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• pp.909-914
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• 2005

This study was conducted to estimate phenotypic and genetic parameters of body condition score (BCS) and reproductive traits in Hanwoo cows. DFREML procedures were applied to obtain variance-covariance components and heritability estimates with single or two-trait models. Estimates of phenotypic correlations of BCS at service with BCS at calving was 0.16 and 0.26 with calving interval, 0.08 with gestation length, and 0.06 with number of services per conception, respectively. Estimates of phenotypic correlation of BCS at calving was 0.10 with calving interval, 0.13 with gestation length, and 0.10 with number of services per conception, respectively. Estimates of phenotypic correlation were low and negative, -0.11 between calving interval and gestation length and -0.13 between gestation length and number of services per conception. Estimates of direct genetic correlation were -0.06, between BCS at service and BCS at calving, 0.37 between BCS at service and BCS at weaning, and -0.18 between BCS at calving and BCS at weaning. Estimates of direct genetic correlation of days from calving to the 1st service were 0.17 with number of services per conception and -0.21 with BCS at service. Estimates of direct genetic correlation for BCS at calving were -0.02 with number of services per conception and -0.08 with BCS at service. Estimates of direct genetic correlation for BCS at weaning were 0.02 with number of services per conception and -0.07 with BCS at service. Estimates of direct heritability from single trait analyses were 0.13 for BCS at service, 0.20 for BCS at calving, 0.02 for BCS at weaning, and 0.20 for number of service per conception, respectively. Estimates of direct heritability were 0.20 for birth weight and 0.10 for weaning weight.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.8
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• pp.1098-1102
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• 2002

A set of 313,169 reproduction records of Japanese Black cows calving between 1987 and 1996 were collected in nation widely Japan to investigate the current level of reproductive performances and the factors influencing the performances such as calving interval, first calving age, services per conception, calving difficulty, non-gestation period and gestation length. All the records of reproductive performances are outcome of artificial insemination. The means of first calving age, calving interval, non-gestation period and gestation length were 25.0 months, 389.9, 101.9 and 287.5 days, respectively. Services per conception were 1.41 and degree of calving difficulty was 1.07, which suggests most of the calving, did not need assistance. There were chronological tendencies that first calving age became younger while calving interval became longer. Differences in reproductive performance were found for seasons and calving numbers. Calving interval became shorter towards the fourth calving but became longer afterwards. The cows calving in May had the shortest calving interval followed by those in April and June and first calving age had a similar tendency. The cows with the standard body condition score showed more favourable reproductive performances compare with those with rather fatty or thin body condition scores.

• Journal of Embryo Transfer
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• v.8 no.2
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• pp.97-103
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• 1993

This study was conducted to determine the main effects of the parity and farrowing season on gestation length and newborn pigs on the basis of the data obtained from 234 litters of Landrace breeds raised at an integrated swine farm in Kyunggy province from January 1991 to December 1992. The results obtained are summarized as follows ; 1. The average gestation length was 115.37 days, and 114.64 days of 8th parity and over was shorter than those of other parities. 2. The averages of litter size and litter size alive per sow were 9.91 and 9.50 heads. The litter size horn at 1st parity was smaller than at other parities, and the litter size in spring was larger than in summer, autumn or winter. 3. The averages of birth weight per litter and pig were 13.53 kg and 1.37 kg. The effect of farrowing season for each litter weight(p<0.01) and pig weight(p<0.05) at birth was significantly higher in spring than other seasons. 4. Incidence of malformation and stillbirth at birth was 4. 10%, and it at 8th parity and over showed the highest rate(7.50%).

• Journal of Embryo Transfer
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• v.26 no.1
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• pp.27-32
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• 2011

This study evaluated the effect of recipient's breed on the gestation length and birth weight of Hanwoo calves produced by Hanwoo ovum pick up (OPU) derived embryos. Embryos of OPU derived Hanwoo cows were transferred into the Hanwoo and Holstein recipients at 6~7 days of estrus cycle. Gestation length was expressed in days from the day of embryo transfer to the birth day of offspring, and birth weight of offspring was recorded within 24 h of birth. Breed of recipient cows (Hanwoo and Holstein) has no effect on overall gestation length ($280.9{\pm}6.2$ vs. $284.4{\pm}9.8$ days) and birth weight of calves ($23.56{\pm}3.75$ vs. $27.70{\pm}7.92\;kg$). The gestation length was higher (p<0.05) for male calves than female calves in both Hanwoo ($283.8{\pm}6.7$ vs. $277.3{\pm}3.3$ days) and Holstein ($287.3{\pm}8.9$ vs. $280.1{\pm}9.1$ days) recipient cows. Birth weight of Hanwoo calves did not differ when Hanwoo recipients ($26.5{\pm}1.3$ vs. $23.3{\pm}1.2\;kg$) were used for embryo transfer. However, male calves were heavier (p<0.05) at birth than that of female calves when embryos were transferred into the Holstein cow ($33.5{\pm}4.9$ vs. $27.8{\pm}4.9\;kg$). In conclusion, the present results demonstrated that breed of recipient cows have no effect on gestation length and birth weight of OPU derived Hanwoo calves. However, gestation length and birth weight of male calves were higher in both Hanwoo and Holstein recipient cows.

• Korean Journal of Veterinary Research
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• v.35 no.1
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• pp.11-17
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• 1995

The development of colon in fetuses between 60, 90, 120 days of gestation and neonates of Korean native goats was investigated by light scanning electron microscopy. The results were summarized as follows : 1. The colonic wall appeared to be differentiated into the epithelium, lamina propria, submucosa, tunica muscularis and serosa in 60-day-old fetus. 2. The epithelium of the colonic villi was stratified in some areas and simple columnar in others at 60- and 90day-old fetus but was only observed simple columnar epithelium at 120-day-old fetus. 3. The goblet cells and the intestinal glands appeared in the colonic mucosa at 90 days of gestation and continued gradually to increase in number during gestation. 4. The well-developed villi of the colon appeared in columnar shape at 60 days of gestation and increased in length and width until 90 days of gestation but the villi appeared to be shorter and degenerated after 120 days of gestation. At birth only the rudiment trace of the villi remained. 5. The tunical muscularis of the colon was continuously developed during gestation period. The inner circular and outer longitudinal muscle layers were distinguishly observed in the colon of 90-day-old fetuses. 6. Scanning electron microscopically, the colonic villi developed in columnar shape or finger-like of fetuses at 60 days of gestation. The of the colonic villi became degenerated after 120 days of gestation. At birth only the rudiment trace of villi remained.

• Journal of applied mathematics & informatics
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• v.5 no.3
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• pp.597-606
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• 1998

In the present study we consider a mathematical model of a non-interactive type autotroph-herbivore system in which the amount of autotroph biomass consumed by the herbivore is assumed to follow a Holling type II functional response. We have also incorpo-rated discrete time delays in the numerical response term to represent a delay due to gestation and in the recycling term which represent a delay due to gestation and in the recycling term which represents the time required for bacterial decomposition. We have derived con-dition for global asymptotic stability of the model in the absence of delays. Conditions for delay-induced asymptotic stability of the steady state are also derived. The length of the delay preserving stability has been estimated and interpreted ecologically.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.12
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• pp.1680-1685
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• 2002

Reproductive data collected from more than 20,000 Japanese Black cows of Hyogo and Shimane Prefectures were analyzed. Averages of age at first calving, gestation length, days open and calving interval were 25.1 mo, 289 d, 112 d and 401 d, respectively. Variance components were obtained by REML procedure and the heritability estimate of age at first calving was 0.22. In gestation length the heritability estimate was 0.40 and no permanent environmental effect was estimated. Estimated variance components of calving interval were similar to those of days open and the heritability and repeatability of calving interval were 0.05 and 0.09, respectively. Random farm effects accounted for approximately 10% of phenotypic variations in all traits. Genetic and farm correlations between age at first calving and calving interval were 0.27 and 0.39, respectively. It was found that temporary environment was an important source of variation for calving intervals of Japanese Black.