• Asian-Australasian Journal of Animal Sciences
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• 제15권9호
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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.

• 한국가축번식학회지
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• 제24권1호
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• pp.35-40
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• 2000

본 연구는 Wistar계 rat를 이용하여 포유기간 중 제한포유시기와 이유시기를 조절하여, 혈중 IGF- I 수준변화에 대해 검토하였다. NL군 (NL)은 포유자의 수를 8 마리로 조절하였으며, RL군 (RL)과 W군 (W)은 RL0, RL0, RL10, RLl5 및 RL20, 그리고 W0, W5, WI0, W15 및 W20으로 각각 5개 군으로 구분하여, RL군은 각 개시일에 포유자의 수를 8마리에서 4마리로 조절하였으며, W군은 각 개시일에 포유자의 수를 완전히 이유시켜 다음과 같은 결과를 얻었다. 1. NL군의 혈중 IGF-I 농도는 분만직후 (Day 0) 750.59$\pm$3.52ng/$m\ell$ 을 나타내어 15일까지 일정한 수준을 유지하다가 그 후 포유 25일에 1,690.20$\pm$4.42ng/$m\ell$ 까지 증가되었다. 2. 포유초기 RL군 (RL0, RL5)의 IGF- I 농도는 포유 10일에 RL0군과 RL5군에서 각각 1,395.90$\pm$3.45 및 1,351.73$\pm$3.23ng/$m\ell$로서 NL 군의 745.96$\pm$2.24ng/$m\ell$ 보다 유의적 (P＜0.05)으로 높게 나타났으나 포유 15일부터는 차이가 없었다. 3. 포유초기 W군의 IGF- I 농도는 이유 후 일주일 정도는 NL군에 비해 높은 수준 (P＜0.05)을 나타내다가 10일경에 NL군과 같은 수준으로 감소하였다. 포유자극의 강약은 난소의 생리적 변화와 함께 혈중 IGF- I의 농도를 조절하는 것으로 사료된다.

• Asian-Australasian Journal of Animal Sciences
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• 제18권9호
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• pp.1231-1236
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• 2005

Genetic parameters for first lactation milk production based on test day (TD) records of 56319 Iranian Holstein cows from 655 herds that first calved between 1991 and 2001 were estimated with restricted maximum likelihood method under an Animal model. Traits analyzed were milk yield and milk fat percentage. Heritability for TD records were highest in second half of the lactation, ranging from 0.11 to 0.19 for milk yield and 0.038 to 0.094 for milk fat percentage respectively. Estimates for lactation records for these traits were 0.24 and 0.26 respectively. Genetic correlations between individual TD records were high for consecutive TD records (>0.9) and decreased as the interval between tests increased. Estimates of genetic correlations of TD yield with corresponding lactation yield were highest (0.78 to 0.86) for mid-lactation (TD3 to TD8). Phenotypic correlations were lower than corresponding genetic correlations, but both followed the same pattern. For milk fat percentage no clear pattern was found. Results of this study suggested that TD yields especially in mid-lactation may be used for genetic evaluation instead of 305-day yield.

• Asian-Australasian Journal of Animal Sciences
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• 제16권5호
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• pp.639-643
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• 2003

The data on 283 Sahiwal cows, sired by 16 bulls, maintained at Cattle Breeding Farm of Nagpur Veterinary College and Dairy Farm of Agricultural College, Nagpur, were considered for the estimation of genetic parameters. Variance and covariance estimates of first lactation traits were obtained using restricted maximum likelihood technique (REML). When first lactation milk yield (FLMY), first lactation length (FLL) and average daily yield (ADY) traits were considered for REML analysis, the heritabilities were $0.184{\pm}0.146$, $0.132{\pm}0.131$ and $0.141{\pm}0.133$, respectively. While, genetic and phenotypic correlations between them were medium to high except phenotypic correlations between FLL and ADY (-0.025). REML procedure considering FLMY, age at first calving (AFC) and first service period (FSP) combination exhibits heritabilities as $0.274{\pm}0.173$, $0.506{\pm}0.233$ and $0.274{\pm}0.172$, respectively. Genetic correlations were $-0.120{\pm}0.376$, $0.225{\pm}0.423$ and $0.365{\pm}0.331$ between FLMY and AFC, FLMY and FSP, AFC and FSP, respectively. Phenotypic correlations were 0.057, 0.289 and 0.123, respectively. Considering all five traits REML combination heritabilities estimated were $0.238{\pm}0.162$, $0.160{\pm}0.139$, $0.136{\pm}0.132$, $0.409{\pm}0.209$ and $0.259{\pm}0.168$ for FLMY, FLL, ADY, AFC and FSP, respectively. The genetic correlations were positive except FLMY and AFC. The phenotypic correlations were also positive except FLL and ADY, ADY and FSP. Almost all estimates were associated with high standard error.

• Asian-Australasian Journal of Animal Sciences
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• 제28권9호
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• pp.1226-1234
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• 2015

The development of effective genetic evaluations and selection of sires requires accurate estimates of genetic parameters for all economically important traits in the breeding goal. The main objective of this study was to assess the relative performance of the traditional lactation average model (LAM) against the random regression test-day model (RRM) in the estimation of genetic parameters and prediction of breeding values for Holstein Friesian herds in Ethiopia. The data used consisted of 6,500 test-day (TD) records from 800 first-lactation Holstein Friesian cows that calved between 1997 and 2013. Co-variance components were estimated using the average information restricted maximum likelihood method under single trait animal model. The estimate of heritability for first-lactation milk yield was 0.30 from LAM whilst estimates from the RRM model ranged from 0.17 to 0.29 for the different stages of lactation. Genetic correlations between different TDs in first-lactation Holstein Friesian ranged from 0.37 to 0.99. The observed genetic correlation was less than unity between milk yields at different TDs, which indicated that the assumption of LAM may not be optimal for accurate evaluation of the genetic merit of animals. A close look at estimated breeding values from both models showed that RRM had higher standard deviation compared to LAM indicating that the TD model makes efficient utilization of TD information. Correlations of breeding values between models ranged from 0.90 to 0.96 for different group of sires and cows and marked re-rankings were observed in top sires and cows in moving from the traditional LAM to RRM evaluations.

• Asian-Australasian Journal of Animal Sciences
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• 제15권3호
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• pp.315-320
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• 2002

Test-day records (n=13677) sampled from 896 ewes in 5-9 (${\mu}$=7.5) monthly test-days were used to estimate genetic and phenotypic parameters of test-day yields, lactation milk yield (TMY), length of the milking period (DAYS) and three measures of persistency of milk yield in Boutsico dairy sheep. Τhe measures of persistency were the slope of the regression line (${\beta}$), the coefficient of variation (CV) of the test-day milk yields and the maximum to average daily milk yield ratio (MA). The estimates of variance components were obtained under a linear mixed model by restricted maximum likelihood. The heritability of test-day yields ranged from 0.15 to 0.24. DAYS were found to be heritable ($h^2$=0.11). Heritability estimates of ${\beta}$, CV and MA were 0.15, 0.13, 0.10, respectively. Selection for maximum lactation yields is expected to result in prolonged milking periods, high rates of decline of yields after peak production, variable test-day yields and higher litter sizes. Selection for flatter lactation curves would reduce lactation yields, increase slightly the length of the milking period and decrease yield variation as well as litter size. The most accurate prediction of TMY was obtained with a linear regression model with the first five test-day records.

• Asian-Australasian Journal of Animal Sciences
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• 제13권5호
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• pp.575-579
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• 2000

First lactation records of 683 Murrah buffaloes maintained at NDRI, Karnal which were progeny of 84 sires used for comparing the heritability estimates of age at first calving, first lactation milk yield and first service period under single and multiple trait models using restricted maximum likelihood (REML) method of estimation under an individual animal model. The results indicated that the heritability estimates may vary under single and multiple trait models depending upon the magnitude of genetic and environmental correlation among the traits being considered. Therefore, a single or multiple trait model is recommended for estimation of variance components depending upon the goal of breeding programme. However, there may not be any advantage of considering a trait with zero or near zero heritability and having no or very low genetic correlation with other traits in the model. Lower heritability estimates of part lactation yield (120-day milk yield) implied that there may not be any advantage of considering this trait in place of actual 305-day milk yield, whereas, comparable heritability estimates of predicted 305-day milk yield suggested that it could be used for sire evaluation to reduce the cost of milk recording under field conditions.

• 한국가축번식학회지
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• 제23권2호
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• pp.95-103
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• 1999

본 연구는 초산의 Wistar 계 rat를 이용하여 포유기간 중 제한포유시기와 이유시기를 조절하여 혈중 progesterone 수준을 검토하였다. 정상포유군 (NL)은 포유자의 수를 8 마리로 조절하였으며, 제한포유군 (RL)과 완전이유군 (W)은 RL0, RL5, RL10, RL15 및 RL20, 그리고 W0, W5, W10, W15 및 W20으로 각각 5 개 군으로 구분하여, 제한포유군은 각 개시일에 포유자의 수를 8마리에서 4마리로 조절하였으며, 완전이유군은 각 개시일에 포유자의 수를 완전히 이유시켰다. 1. 포유자의 발육상태는 제한포유군에서 정상포유군보다 성장이 유의적 (P＜0.05)으로 증가하였고, 또한 분만직후 (RL0) 와 포유 5(RL5), 10(RL10), 15(RLl5) 일에 제한포유를 실시한 군에서는 시간이 경과함에 따라 정상포유군에 비해 유의적 (P＜0.05) 으로 증가하였으나, 포유 20 일(RL20) 에 제한포유군에서는 정상포유군과 차이가 없었다 . 초산 rat 의 임신기간은 21.53$\pm$0.04일이었고 산자수는 13.75$\pm$0.07 마리였다. 2. 포유기간 중 모체의 성주기 변화는 정상포유군은 발정징후가 관찰되지 않았으나 분만직후 제한포유군은 20 일을 전후하여 불규칙적인 성주기가 관찰되었고, 분만직후 완전이유군은 10일을 전후하여 정상적인 성주기가 관찰되었다. 3. 정상포유군의 progesterone 농도는 포유 0 일에 33.16$\pm$2.64ng/$m\ell$에서 포유 10 일에 122.55$\pm$3.68ng/$m\ell$ 까지 증가하여 포유 20 일까지 높은 수준을 유지하다가 그 후 25 일에 97.30$\pm$3.21ng/$m\ell$ 까지 급속히 감소 (P＜0.05) 하였다. 포유초기 (RL0, RL5)와 포유중기 (RL10)의 제한포유군은 제한포유실시 이후 5일 까지는 정상포유군과 같은 수준을 유지하다가 그 후 급격히 (P＜0.05) 감소하였다. 결론적으로 흰쥐에 있어서 분만 후 포유자의 포유자극이 모체 난소의 기능에 중요하게 작용하는 것으로 사료된다.

• Asian-Australasian Journal of Animal Sciences
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• 제31권6호
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• pp.798-803
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• 2018

Objective: The objective of this study was to estimate the genetic parameters for milk ${\beta}$-hydroxybutyrate (BHBA), acetone (Ac), fat protein ratio (FPR), and energy balance (EB) using milk test day records and investigate the effect of early lactation FPR and EB on milk ketone body concentrations. Methods: Total 262,940 test-day records collected from Korea Animal Improvement Association during the period of 2012 to 2016 were used in this study. BHBA and Ac concentrations in milk were measured by Fourier transform infrared spectroscopy (FTIR). FPR values were obtained using test day records of fat and protein percentage. EB was calculated using previously developed equation based on parity, lactation week, and milk composition data. Genetic parameters were estimated by restricted maximum likelihood procedure based on repeatability model using Wombat program. Results: Elevated milk BHBA and Ac concentrations were observed during the early lactation under the negative energy balance. Milk FPR tends to decrease with the decreasing ketone body concentrations. Heritability estimates for milk BHBA, Ac, EB, and FPR ranged from 0.09 to 0.14, 0.23 to 0.31, 0.19 to 0.52, and 0.16 to 0.42 respectively at parity 1, 2, 3, and 4. The overall heritability for BHBA, Ac, EB and FPR were 0.29, 0.32, 0.58, and 0.38 respectively. A common pattern was observed in heritability of EB and FPR along with parities. Conclusion: FPR and EB can be suggested as potential predictors for risk of hyperketonemia. The heritability estimates of milk BHBA, Ac, EB, and FPR indicate that the selective breeding may contribute to maintaining the milk ketone bodies at optimum level during early lactation.

• Asian-Australasian Journal of Animal Sciences
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• 제5권1호
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• pp.107-112
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• 1992

Feeding of bypass protein to lactating animals have been suggested by many research scientists as a way to increase the nutrient supply at the intestinal level thereby enhance animal production in ruminant animals. A feeding trial with a formulated bypass protein feed on straw based ration was carried out by using lactating cross bred cows at the stage of 4th month of their lactation. Bypass protein feed was fed at 5 different levels. Urea Molasses Block was used as a nitrogen source to the rumen microflora. In order to reduce the heat increment straw intake was restricted to all the animals. Urea Molasses Block intake was noticed varying in proportion with the bypass protein feed intake. Milk production was observed increasing in accordance with the level of bypass protein feed intake. However, the maximum response was noticed in cows that were fed 3 kg bypass protein feed. The nutrient availability at this stage was below the NRC (1988) requirements. Other remarkable finding was that the cows maintained the persistency of milk production even after 3rd month of lactation when the ambient temperature was $40^{\circ}C$.