• Journal of Veterinary Clinics
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• v.35 no.6
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• pp.251-257
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• 2018

We determined the relationships between calving season and the incidence of postpartum disorders, milk yield, and reproductive performance in dairy cows. Data regarding cow parity, postpartum disorders, milk yield, and reproduction were collected from 1,478 lactations. The incidence of retained placenta was higher in spring- and summer-calving cows than in autumn- and winter-calving cows (P < 0.05). The incidence of septicemic metritis was highest in spring- and summer-calving cows, and was higher in autumn-calving cows than in winter-calving cows (P < 0.05). The incidence of metabolic disorders was higher in summer-calving cows than in autumn- and winter-calving cows (P < 0.01). The mean milk yield 1 and 2 months after calving was higher in spring-calving cows than in summer-calving cows (P < 0.05). The percentage of cows that had resumed cycling, defined by detection of a corpus luteum using ultrasonography 4 weeks after calving, was highest in autumn-calving cows, and was higher in summer- and winter-calving cows than in spring-calving cows (P < 0.05). The hazard of first insemination by 150 days after calving was higher in summer- and autumn-calving cows (hazard ratio [HR] = 1.19; P < 0.05) than in spring-calving cows. The hazard of pregnancy by 210 days after calving was also higher in summer-calving (HR = 1.24; P < 0.05) and autumn-calving (HR = 1.59; P < 0.0001) cows than in spring-calving cows. The probability of conception at the first insemination was higher (P < 0.0001) in autumn-calving (odds ratio [OR] = 1.96) and winter-calving (OR = 2.04) cows than in spring-calving cows. In conclusion, spring calving is associated with the worst, and autumn calving with the best, postpartum health and reproductive performance, whereas milk yield is higher in spring-calving cows than in summer-calving cows. Therefore, an effective strategy to support postpartum health and fertility should be instituted for spring-calving dairy cows kept in the Korean climate.

• 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.24 no.2
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• pp.127-130
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• 2009

The purpose of this study was to determine the effect of cows parity and calving seasons on the subsequent reproductive performance of the herd of Korean native cows raised under the same condition. With the parity of the cows ranged 1 to 4 (mean: 1.9), significant associations were found between parity and calving interval (p<0.05). Calving interval of the primiparous cows group was 395.0 ${\pm}$ 16.5 days, which was the longest calving interval among the four groups. On the other hand, calving interval of the second parity group was 333.7 ${\pm}$ 3.6 days. The primiparous cows had tendencies that long interval from calving to conception and small number of service per conception relatively when compared with the multiparous cows. In the case of calving season, the interval from calving to first service was short in summer and winter relatively. The interval from calving to conception in summer was the shortest in four seasons. The number of service per conception was larger in spring and winter and smaller in summer and autumn. Calving in spring showed delayed reproductive performance and calving in summer showed desirable reproductive performance.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.11
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• pp.1511-1517
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• 2013

This study was performed to estimate the effect of age at first calving and first two calving intervals on productive life and life time profit in Korean Holsteins. Reproduction data of Korean Holsteins born from 1998 to 2004 and lactation data from 276,573 cows with birth and last dry date that calved between 2000 and 2010 were used for the analysis. Lifetime profit increased with the days of life span. Regression of Life Span on Lifetime profit indicated that there was an increase of 3,800 Won (approximately $3.45) of lifetime profit per day increase in life span. This is evidence that care of each cow is necessary to improve net return and important for farms maintaining profitable cows. The estimates of heritability of age at first calving, first two calving intervals, days in milk for lifetime, lifespan, milk income and lifetime profit were 0.111, 0.088, 0.142, 0.140, 0.143, 0.123, and 0.102, respectively. The low heritabilities indicated that the productive life and economical traits include reproductive and productive characteristics. Age at first calving and interval between first and second calving had negative genetic correlation with lifetime profit (-0.080 and -0.265, respectively). Reducing age at first calving and first calving interval had a positive effect on lifetime profit. Lifetime profit increased to approximately 2,600,000 (2,363.6) from 800,000 Won ($727.3) when age at first calving decreased to (22.3 month) from (32.8 month). Results suggested that reproductive traits such as age at first calving and calving interval might affect various economical traits and consequently influenced productive life and profitability of cows. In conclusion, regard of the age at first calving must be taken with the optimum age at first calving for maximum lifetime profit being 22.5 to 23.5 months. Moreover, considering the negative genetic correlation of first calving interval with lifetime profit, it should be reduced against the present trend of increase.

• Animal Bioscience
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• v.37 no.5
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• pp.944-951
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• 2024

Objective: Parturition is crucial for dams, their calves, and cow managers. The prediction of calving time, which assists cow managers to decide on the relocation of cows to maternity pens and necessity of human supervision, is a pivotal aspect of livestock farming. However, existing methods of predicting calving time in dairy cows based on hormonal changes and clinical symptoms are time-consuming and yield unreliable predictions. Accordingly, we investigated whether heart rate variability (HRV) which is a non-invasive assessment of autonomic nervous system (ANS) activity and behavior during the prepartum period would be useful for predicting calving time in dairy cows. Methods: Eight pregnant cows were surveilled under electrocardiogram and video recordings for HRV and behavioral analyses, respectively. HRV parameters in time and frequency domains were evaluated. A 24-h time budget was calculated for each of six types of behavior (standing and lying with or without rumination, sleeping, and eating). Results: Heart rate on calving day is considerably higher than those recorded on the days preceding calving. Low frequency power declined, whereas high frequency power escalated on the calving day compared to the period between 24 and 48 h before calving. The time budget for ruminating while lying decreased and that while standing increased markedly on the calving day compared to those allocated on the preceding days; nonetheless, the total time budget for ruminating did not differ during the prepartum period. Conclusion: We elucidated the ANS activity and behavioral profiles during prepartum period. Our results confirm that HRV parameters and behavior are useful for predicting calving time, and interestingly indicate that the time budget for ruminating while standing (or lying) may serve as a valuable predictor of calving. Collectively, our findings lay the foundation for future investigations to determine other potential predictors and formulate an algorithm for predicting calving time.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.1
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• pp.56-60
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• 1999

Production and reproduction data of 47 Nili-Ravi buffaloes (162 records) were analyzed with regression techniques. Average lactation milk yield was $2,020.04{\pm}44.59$ liters, lactation length $277.42{\pm}5.70$ d and calving interval $467.10{\pm}11.58$ d. The ranges for these parameters respectively were : 609-3591 lit, 122-614 d and 228-982 d. Year of calving and lactation length had significant effect on total milk yield (p < 0.01), whereas other factors such as month of calving, lactation number and calving interval had no effect on total lactation milk yield. Year of calving had influenced significantly other traits (p < .01) such as calving interval and lactations completed. This indicated considerable environment role in buffalo productivity. Effect of month of calving on total lactation milk yield and other traits was however, found to be non-significant. Nili-Ravi buffaloes produced maximum milk during their first three lactations as compared to subsequent lactations. Regression model explained 40 percent variation in total lactation milk yield due to factors analyzed : animal (dam), year and month of calving lactation length and calving interval.

• Asian-Australasian Journal of Animal Sciences
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• v.10 no.3
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• pp.313-317
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• 1997

Data collected from crossbred dairy cattle at the Institut Haiwan, Kluang, were used to evaluate the effects of breed of sire, percentage of Bos taurus inheritance and season of birth on some calving traits. Breed of sire effect was significant on age at first service (p < 0.01), age at first calving (p < 0.01) and postpartum interval to first service (p < 0.05) but not on calving interval (p > 0.05). Linear contrasts indicate that crossbred-sired cows had first service 593 days earlier and first calving 508 days earlier than purebred-sired cows. Cows sired by Friesians, however, had the earliest first service (466 days) and were among the earliest at first calving (917 days). However, the crossbred-sired cows had slightly longer post-partum interval to first service (13 days longer) and calving interval (20 days longer). Percentage of B. taurus inheritance affected (p < 0.01) all the calving traits studied. In general, the cows with 50% inheritance had the best calving performance. Season of birth had no effect (p > 0.05) on them.

• 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.

• Journal of Animal Science and Technology
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• v.63 no.4
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• pp.740-750
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• 2021

This study was performed to investigate genetic relationship of age at first calving (AFC) with body development and reproduction capacity in female Hanwoo. The data sets of 52,299 reproduction records of 19,566 heads calved from 2011 to 2019 and conformation records of 19565 heads born from 1997 to 2017 were analyzed by separating them based on age at first calving. In the analysis, conformation traits included the body condition score (BCS), height (HT), body width (BW), hip bone length (HL), hip bone width (HW), and final score (FS). The heritability and genetic correlation of AFC with conformation traits and calving interval (CI) were analyzed. The heritability for AFC was 0.716, 0.087, and 0.097 for the before and after 24 months and combined data, respectively. The genetic correlation of AFC before 24 months with BCS was -0.778, -0.600 with BW, and 0.442 with HT. The genetic correlation of AFC after 24 months with HT was -0.826, -0.706 with BW, -0.623 with HL, -0.456 with HW, and -0.675 with FS. When the first calving age of young heifers approached 24 months, BCS and BW decreased, and HT increased. When first calving is delayed to after 24 months, the conformation traits become smaller, which indicates that conformation to some extent affects the delay in AFC. The genetic correlation between CI and AFC was -0.116, 0.307, and 0.250 for the before and after 24 month of AFC and combined data, respectively. When first calving date approached 24 months, CI was reduced. The obtained results suggest that it is important that first calving occurs at an appropriate age. Additional research is needed to perform proper genetic evaluation of first calving age in Hanwoo cattle in Korea.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.2
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• pp.153-158
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• 2004

Data containing 14,188 lactation and reproductive records of Korean Holstein cows at first parity distributed across 3,734 herd-year-season groups were analyzed to get genetic (co)variance estimates for milk yield, fat yield, calving ease, and days open. Milk and Fat yields were adjusted to 305 d. Heritabilities and genetic correlations were estimated in two different animal models on which were included direct genetic effects (Model 1) and direct+maternal genetic effects (Model 2) using REML algorithms. Milk and fat yields were affected by age at first calving as linear and quadratic. Heritability estimates of direct effects were 0.25 for milk yield, 0.17 for fat yield, 0.03 for calving ease and 0.03 for days open in Model 2. These estimates for maternal effects were 0.05, 0.08, 0.04 and less than 0.01 for each corresponding trait. Milk productions at first lactation were to show genetically favorable correlation with calving ease and days open for direct genetic effects (-0.24 - -0.11). Moreover, calving ease was correlated with days open of 0.30 for direct genetic effects. Correlations between direct and maternal effects for each trait were negatively correlated (-0.63 - -0.32). This study suggested that maternal additive genetic variance would be not ignorable for genetic evaluation of milk production as well as reproductive traits such as calving ease and days open at first parity. Furthermore, difficult calving would genetically influence the next conception.