• Asian-Australasian Journal of Animal Sciences
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• v.20 no.5
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• pp.661-668
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• 2007

Data on 1,037 Nili-Ravi buffaloes from four institutional herds were used to study lifetime milk yield, herd life, productive life and breeding efficiency. A general linear model was used to study the environmental effects while an animal model having herd, year of birth and age at first calving (as covariate) along with random animal effect was used to estimate breeding values. The lifetime milk yield, herd life, productive life and breeding efficiency averaged $7,723{\pm}164$ kg, $3,990{\pm}41$ days, $1,061{\pm}19$ days and 64 percent, respectively. All the traits were significantly (p<0.01) affected by the year of birth and herd of calving, while the herd life was also affected (p<0.01) by the age at first calving. The heritabilities for lifetime milk yield, herd life, productive life and breeding efficiency were $0.093{\pm}0.056$, $0.001{\pm}0.055$, $0.144{\pm}0.079$ and 0.001, respectively. The definition for productive life, where each lactation gets credit upto 10 months had slightly better heritability and may be preferred over the definition where no limit is placed on lactation length. The genetic correlation between productive life and lifetime milk yield was low but high between productive life and herd life. The selection for productive life will increase herd life while lifetime milk yield will also improve. The overall phenotypic trend during the period under the study was negative for lifetime milk yield (-280 kg/year), herd life (-93 days), productive life (-42 days/year) and breeding efficiency (-0.36 percent/year), whereas the genetic trend was positive for lifetime milk yield (+15 kg/year) and productive life (+4 days/year).

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.4
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• pp.519-526
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• 2019

Objective: We determined the risk factors limiting first service conception (FSC) rate in dairy cows and their economic impact. Methods: Data were collected from 790 lactations regarding cow parity, peri- and postpartum disorders, body condition score (BCS), reproductive performance, and expenses associated with reproductive management (treatment, culling, and others). Initially, we identified the risk factors limiting FSC rate in dairy cows. Various biological and environmental factors, such as herd, cow parity, BCS at 1 month postpartum and first artificial insemination (AI), resumption of cyclicity within 1 month of calving, year, AI season, insemination at detected estrus or timed AI, peri- and postpartum disorders, and calving to first AI interval, were evaluated. Next, we evaluated the economic impact of the success or failure of FSC by comparing the expense associated with reproductive management until conception between cows that did or did not conceive at their first service. Results: Cows with BCS <3.0 had a lower probability of conceiving at first insemination (odds ratio [OR] = 0.64, p<0.05) than cows with $BCS{\geq}3.0$. Cows inseminated during summer were less likely to conceive (OR = 0.44, p<0.001) than cows inseminated during spring. Cows with peri- or postpartum disorders were less likely to conceive (OR = 0.55, p<0.001) than cows without disorders. Survival curves generated using MedCalc showed an 81 day extension in the mean interval between calving and conception in cows that failed to conceive over those that did conceive at first insemination. Cows failing conceive required additional expenditure on reproductive treatment ($55.40) and other management ($567.00) than cows that conceived at first insemination. Conclusion: Lower BCS, hot weather at first insemination, and peri- and postpartum disorders are risk factors limiting FSC, which result in an economic loss of $622.40 per dairy cow.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.9
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• pp.1267-1272
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• 2002

The present research was undertaken to monitor the effects of restricted and ad. libitum feeding during last trimester of pregnancy on the performance of crossbred dairy cows and their calves. For this purpose two groups of crossbred cows having eight animals in each group were put into two plane of nutrition during their last three months of pregnancy. Dietary energy level in one group was calculated as per Ministry of Agriculture, Fisheries and Food, (MAFF, UK) and the cows on other group received ad. libitum feeding (concentrate level similar to MAFF, recommendation+ad. libitum roughage). After calving, the cows of both groups were given same diet (ad. libitum) to study the effect of feeding during pregnancy on subsequent lactation performance of the cows. It was observed that during pre-calving period cows on ad. libitum feeding gained significantly (p<0.05) more body weight than that of cows on restricted feeding ($38.50{\pm}6.04$ vs $21.37{\pm}8.04kg/cow$). There was no significant differences between the birth weight of calves of restricted ($21.31{\pm}2.18kg$) and ad. libitum ($20.31{\pm}3.27kg$) groups. Dietary energy intake of ad. libitum group ($50.22{\pm}4.24$ MJ ME/d/cow) was significantly higher (p<0.01) than that of restricted group ($39.76{\pm}1.03$ MJ ME/d/cow). During lactation period cows that were on restricted feeding produced little more milk (3.06 lit/cow/day), than that of the cows on ad. libitum feeding (2.84 lit/cow/day). Although growth rate of the calves of restricted group upto one month ($0.23{\pm}0.09kg/calf/d$) was significantly (p<0.01) higher than that of ad. libitum group ($0.17{\pm}0.08kg/calf/d$) but after four months the growth rate of the calves of two groups become nearly similar ($0.35{\pm}0.02$ vs $0.37{\pm}0.03kg/calf/d$) and difference between them was non-significant. During lactation period cows of restricted group gained little weight but cows of ad. libitum group lost significantly (p<0.05) more weight. Per day metabolizable energy intake in both group during lactation period was nearly similar (67.54 vs 69.58 MJ ME). It is concluded that ad. libitum feeding during last trimester of pregnancy is neither economic for getting maximum milk yield nor for calf growth rate and MAFF, recommended level of dietary energy during that period could be applied on our pregnant crossbred dairy cows.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.3
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• pp.390-395
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• 2006

This work was conducted to study the effect of rumen-protected choline (RPC) addition on milk performance and blood metabolic parameters in transition dairy cows. In Experiment 1, fourteen Chinese Holstein dairy cows were supplemented with 0 or 20 g/d of RPC from 7 d before expected calving to 21 d post partum. Feeding of RPC tended to increase milk yield and milk protein percentage, while milk fat and lactose percentage were not changed. Plasma concentrations of glucose tended to increase as cows consumed RPC, while plasma concentrations of triglycerides, very low density lipoproteins, cholesterol and nonesterified fatty acids were not significantly different between the two groups. In Experiment 2, thirty-six Chinese Holstein dairy cows were supplemented with 0, 30, 60 or 90 g/d RPC from 15 d before expected calving to 15 d post partum. Feeding of RPC tended to increase yield of milk and 4% fat-corrected milk for all the lactating cows, and milk composition was similar among the four groups. Plasma concentrations of glucose were remained at a higher level in 30 or 60 g/d RPC-supplemented groups, and nonesterified fatty acids were decreased in the 30 g/d group. Concentrations of triglycerides tended to reduce in 30 and 90 g/d RPC-supplemented animals, and cholesterol was reduced in 0 or 30 g/d group. These results suggest that RPC addition tended to increase milk yield and improve blood metabolic parameters during transition dairy cows, and feeding 30 g/d of RPC may be the optimal.

• Journal of Animal Science and Technology
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• v.65 no.3
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• pp.588-595
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• 2023

The aim of this study was to investigate the effects of heat stress on milk traits in South Korea using comprehensive data (dairy production and climate). The dataset for this study comprised 1,498,232 test-day records for milk yield, fat- and protein-corrected milk, fat yield, protein yield, milk urea nitrogen (MUN), and somatic cell score (SCS) from 215,276 Holstein cows (primiparous: n = 122,087; multiparous: n = 93,189) in 2,419 South Korean dairy herds. Data were collected from July 2017 to April 2020 through the Dairy Cattle Improvement Program, and merged with meteorological data from 600 automatic weather stations through the Korea Meteorological Administration. The segmented regression model was used to estimate the effects of the temperature-humidity index (THI) on milk traits and elucidate the break point (BP) of the THI. To acquire the least-squares mean of milk traits, the generalized linear model was applied using fixed effects (region, calving year, calving month, parity, days in milk, and THI). For all parameters, the BP of THI was observed; in particular, milk production parameters dramatically decreased after a specific BP of THI (p < 0.05). In contrast, MUN and SCS drastically increased when THI exceeded BP in all cows (p < 0.05) and primiparous cows (p < 0.05), respectively. Dairy cows in South Korea exhibited negative effects on milk traits (decrease in milk performance, increase in MUN, and SCS) when the THI exceeded 70; therefore, detailed feeding management is required to prevent heat stress in dairy cows.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.4
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• pp.511-514
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• 1999

Data pertaining to 1111 first lactation performance record of Karan Fries (Holstein-Friesian $\times$ Zebu) cows spread over a period of 21 years and sired by 72 bulls were used to examine the efficiency of sire indices for lactation milk production using auxiliary traits. First lactation length, first service period, first calving interval, first dry period and age at first calving were considered as auxiliary traits. The efficiency of this method was compared with simple daughter average index (D), contemporary comparison method (CC), least-square method (LSQ), simplified regressed least-squares method (SRLS) and best linear unbiased prediction (BLUP) for lactation milk production. The relative efficiency of sire evaluation methods using one auxiliary trait was lower (24.2-32.8%) in comparison to CC method, the most efficient method observed in this study. Use of two auxiliary traits at a time did not further improve the efficiency. The auxiliary sire indices discriminate better among bulls as the range of breeding values were higher in these methods in comparison to conventional sire evaluation methods. The rank correlation between breeding values estimated using auxiliary traits were high (0.77-0.78) with CC method. The rank correlation among auxiliary sire indices ranged from 0.98 to 0.99, indicating similar ranking of sire for breeding values of milk production in all the auxiliary sire indices.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.9
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• pp.1192-1198
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• 2011

Peri-partum metabolic profile was evaluated in winter and summer calving, with 15 Murrah buffaloes in each seasonal group. In summer calvers, significantly lower values were observed for blood plasma urea nitrogen (BUN) at day 30 pre-partum (p<0.05), on calving day (p<0.05) and at all other stages (p<0.01); plasma non-esterified fatty acids (NEFA) values were significantly lower on day 30 pre-partum (p<0.01) and on day 60 post-partum (p<0.05). This was associated with significant reduction in days to first service (DFS) and service per conception (SPC) and an overall better reproductive performance in terms of service period, risk to first service on days 60, 90 and >90, and pregnancy risk to first service up to days 60 and 90. This may be attributed to better pre-partum nutritional status. Cervical and uterine involution were completed in fewer days, involutional changes took place at a faster pace and there were a lower number of abnormal involutional changes in winter compared to summer season. This may be attributed to better post-partum nutrition and less environmental stress. However, validation requires further targeted cohort investigation with a large sample size.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.3
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• pp.331-334
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• 2003

The assessment of reproductive potentials of female gayal under semi-intensive management was conducted with 18 animals in Bandarban hilly area of Bangladesh. Age at first estrous (days), age at first conception (days), length of estrous cycle (days), number of service per conception (natural), gestation period (days), age at first calving (days), and calving interval (natural service) (days) of gayal were $598.2{\pm}168.44$, $723{\pm}169.94$, $21.86{\pm}2.93$, 1.41, $296.05{\pm}3.87$, $1014.42{\pm}260.32$ and $465{\pm}80.48$ respectively. Daily milk yield and lactation length of gayal were $304.98{\pm}30.46ml/day$ and $116.67{\pm}8.08days$. Gayal male calves had higher birth weight (19.67 kg) than female calves (15.58 kg) in first lactation. Birth weight increases in second and third lactation than first lactation in both male and female calves. Highest conception rate observed in winter season and 70.60% successful conception occur when service was given within 21-30 h of estrous. Maximum number of female gayal use to come in estrous in winter and calved in monsoon and autumn. Cervicitis and irregular heat were the most reproductive problems followed by metritis, case of abortion, anestrous and repeat breeding. From this study it was observed that the reproductive performance of gayal is very close with the domestic cattle. It may use as beef cattle for the hilly regions of Bangladesh.

• Korean Journal of Veterinary Research
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• v.27 no.1
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• pp.137-140
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• 1987

Information on certain reproductive traits were obtained from field material. The data for this study were taken from 1,111 breeding records of 273 cows and 193 heifers at Koheung, Chonnam, during the period 1979 to 1984. The cattle were bred by artificial insemination; only one or two cattle were reared by one farmer. The heifers were first bred at 551.75 days after they were born; they were pregnant at 569.06 days after birth. The average estrous cycle length was 21 days; the average number of inseminations per conception was 1.56. The non-return rate for first inseminations for cows and heifers was 62.5% and 59.6%, respectively. The gestation length was 285.79 days. Of 1,111 viable calved born 582 were male, giving a sex ratio of 100:110. The average length between calving and first insemination was 88.9 days; average calving interval was 397.69 days.

• Korean Journal of Agricultural Science
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• v.8 no.1
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• pp.72-81
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• 1981

This study was conducted to determine the differences in the growth and milk production performance of Holstein Crossbreds (Korean Native Cattle(♀)${\times}$Holstein(♂)) and Korean Native Cattle produced at the Livestock Experiment Station of the Office of Rural Developement from 1973 to 1978. The number of heifers and cows used in this experiment were 15 head of Korean Native Cattle and 11 head pf Holstein Crossbreds Cattle. Body weight and body measurements were taken at birth, 6, 12, 24 and 36 months of age, however, body measurements were not taken at birth. Milk production was checked from the 11 th day to 180th day after calving. The data was analyzed using the least square procedure in order to estimate the effect of the mating group, year of birth, calving season and parity. The results obtained from this study were as follows: 1. The body weights of the Holstein Crossbreds were heavier than the body weights of purebred Korean Native Cattle. The body weight of the Holstein Crossbreds averaged 28.09kg, 146.64kg, 254.48kg, 392.04kg and 454.46kg at birth, 6, 12, 24 and 36 months of age, respectively. However, the body weights of purebreds Korean Native Cattle averaged 22.45kg, 132.82kg, 220.68kg, 363.54kg and 365.54kg at the same ages. 2. The year of birth affected on body weight at each point during the growing stage, except birth, heifers born in the spring and autumn were heavier than the others, but calving season did not affect on body weight during the growing stage except at birth and 6 months. 3. Parity showed significant differences on body weight in the growing stage. Calves from the 5th parity had a tendency to be heavier than the other calves. 4. The year of birth, calving season and parity at calving had no affect on the change of body measurements, but the wither height, hip height, chest depth, chest girth and hip width were significantly greater in the Holstein Crossbreds at 24 months of age. 5. Mating groups had a significant affect on milk production during the growing stage. Year of birth and calving season did not affect milk production, but parity was significant from 11 days after calving. 6. The least-squares means used to determine the daily milk production were 3.60 and 8.26kg/day for Korean Native Cattle and the Holstein Crossbreds, respectively.